biodiversity conservation in the context of tropical forest management

E N V R ON M E N T 21653~~~~~D E P A R-T M E N T

( 6) ~~P A P E R -SPAE.7-. PAPERS ~~~~~~~~~~~PAPER N.75*

4dw ~ TOWARD ENVIRONMENTALLY AND SOCIALLY SUSTAINABLE DEVELOPMENT

B.IODIVERSITY SERIES - IMPACT STUDIES

BiodiversityConservation in theContext of TropicalForest Management

Francis E. PutzKent H. RedfordJohn G. RobinsonRobert Fimbel'Geoffrey M. Blate

September 2000

The World Bank

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O THE WORLD BANK ENVIRONMENT DEPARTMENT

BiodiversityConservation in theContext of TropicalForest Management

Francis E. PutzKent H. RedfordJohn G. RobinsonRobert FimbelGeoffrey M. Blate

September 2000

Papers in this series are not formal publications of the World Bank. They are circulated to encourage thought and discussion. The useand citation of this paper should take this into account. The views expressed are those of the authors and should not be attributed tothe World Bank. Copies are available from the Environment Department, The World Bank, Room MC-5-126.

The International Bank for Reconstructionand Development/THE WORLD BANK1818 H Street, N.W.Washington, D.C. 20433, U.S.A.

Manufactured in the United States of AmericaFirst printing September 2000

About the authors:Francis E. Putz ([email protected]) is Professor of Botany at the University of Florida; Kent H. Redford([email protected]) is Director of Biodiversity Analysis and Coordination at WCS; John G. Robinson([email protected]) is Senior Vice President and Director for International Conservation at WCS; RobertFimbel ([email protected]) is Chief Scientist for the Washington State Parks and Recreation Commis-sion; and Geoffrey M. Blate ([email protected]) is a Ph.D. candidate at the University of Florida.

Substantial background material for this paper was provided by D. Nepstad, M. Guariguata, R. Noss, andC. Peters. We also acknowledge the contributions of E. Bennett, J. Ewel, P. Frumhoff, E. Losos, K.MacKinnnon, A. Moad, G. Platais, A. Plumptre, and R. Plumptre.

This document does not represent an endorsement of any particular World Bank policy by the WildlifeConservation Society.

'WC s

The Wildlife Conservation Society (WCS) is dedicated to being the most effective conservation organiza-tion, protecting and promoting a world rich in wildlife and wilderness.

WCS manages more than 300 field projects in 53 countries and develops award-winning environmentaleducation programs for schools in the U.S. and abroad.

At its celebrated wildlife parks in New York-the Bronx Zoo, the New York Aquarium, and Central Park,Queens and Prospect Park Wildlife Centers-WCS inspires over 4.5 million annual visitors to care aboutwildlife and wild lands and to participate in their conservation.

To leam more about WCS, visit www.wcs.org.

Biodiversity SeriesImpact Studies

These "Impact Studies" are a subset of the Biodiversity Series of the World Bank'sEnvironment Department Papers. Within this subset the broader question of what thepositive and negative impacts of human activities on biodiversity is addressed.

The following studies have been published in this series:

1. Biodiversity Conservation in the Context of Tropical Forest Management2. Hunting of Wildlife in Tropical Forests-Implicationsfor Biodiversity and Forest Peoples

Contents

PREFACE V

ExEcurlvE SUMMARY VIl

Chapter 1Introduction 1

Chapter 2Disaggregating "Biodiversity" 3

Chapter 3Disaggregating "Logging" 7

Logging intensities 7Log yarding methods 9Logging and other silvicultural treatments 11Reducing the impacts of logging and other silvicultural treatments 12

Chapter 4Impacts of Forest Management on Biodiversity 15

Background 15Landscape impacts (see Appendix I) 16Ecosystem impacts (see Appendix II) 19Community impacts (see Appendix III) 21Species impacts (see Appendices V and VI) 22Genetic impacts (see Appendix VII) 25

Chapter 5Overview of Biodiversity Conservation in Relation to Logging and otherSilvicultural Treatments 27

Synthesis 27Troubling assumptions 29Conclusions 30

Chapter 6Recommendations 33

Biodiversity Series - Impact Studies iii

Biodiversity Conservation in the Context of Tropical Forest Management

APPENDICES

I Impacts of Logging (and other silviculture treatments where noted) on the Landscape Componentof Biodiversity in Tropical Forests 35

II Impacts of Logging (and other silviculture treatments where noted) on the Ecosystem Componentof Biodiversity in Tropical Forests 39

III Impacts of Logging (and other silviculture treatments where noted) on the Community Compo-nent of Biodiversity in Tropical Forests 43

IV Bird responses (density based on inter-site comparisons) to Logging in Tropical Forests,Organized by Feeding Guild 51

V Impacts of Logging (and other silviculture treatments where noted) on the Species Component ofBiodiversity in Tropical Forests 53

VI Primate responses (by feeding guild) to Logging in Tropical Forests 57VII Impacts of Logging (and other silviculture treatments where noted) on the Genetic Component of

Biodiversity in Tropical Forests 61

GLOSSARY 63

BIBLIOGRAPHY 67

Boxes

1 Few tropical forests are logged or burned only once 92 Enrichment planting 123 Is reduced-impact logging (RIL) cheaper? 134 The critical role of production forests in maintaining biodiversity in the tropics 175 Hunting in logged tropical forests 236 Lesser-known species-Marketing challenges, silvicultural impediments, or desirable

diversity? 24

Figures1 Logging intensities (m3 /ha) for tropical forests 82 Generalized ranges of direct biodiversity impacts of timber yarding methods used for tropical

forest logging as a function of level of technological sophistication required 103 Some impacts of logging on biodiversity as a function of distribution of logging activities and

logging intensity 184 Expected effects of a range of forest uses on the components of biodiversity 275 Generalized biodiversity impacts plotted against expected short-term financial returns to forest

owners or concessionaires 286 Generalized biodiversity impacts resulting from different approaches to forest management for

timber 29

Tables1 Components and attributes of tropical forest biodiversity that might be influenced by logging

and other silvicultural activities 4

iv Environment Departrnent Papers

Preface

This paper was prepared as part of the World One of the most important forest uses is loggingBank's Overlay Program and as a contribution or timber harvesting. Logging is the mostto the Bank's ongoing Forest Policy review. lucrative forest use and can cause severe directThe Overlays Program, launched by the World and indirect environmental impacts. ThisBank in partnership with bilateral donors and analysis evaluates the impacts of logging onNGOs, seeks to internalize global externalities biodiversity in tropical forests based on ainto national environmental planning and the thorough review of the literature and on theBank's sector work, operations, and its best expert opinion.dialogue with governments and partners. It isan iterative process, combining conceptual The study was commissioned from the Wildlifestudies, reviews of state-of-the-art techniques Conservation Society (WCS). A draft paper wasfor measuring and mitigating local, national prepared by WCS and the University of Floridaand global externalities, and testing these and was distributed to an expert review panel.concepts and tools in country-level studies as a Supported by the Forest Policy Implementationmeans of identifying good practices for Review and Strategy Process, these reviewerscountry planners and Bank task managers. The convened in Washington with the authors andresults will help guide national actions to Bank staff in late February, 1999 for aconserve biodiversity, reduce greenhouse gas productive two day workshop after which theemissions, and protect international waters. paper was revised.

The Overlays add a new dimension to Forests will continue to be harvested and timbertraditional sector economic planning by harvesting will continue to be an importantanalyzing environmental impacts and component of sustainable forest management.opportunities to internalize global This is a reality we cannot escape. Therefore, asexternalities. This analysis launches the this practice continues we need to assure"Impact Studies" which asks the broader ourselves that it is ecologically andquestion of what the positive and negative environmentally sustainable. The World Bankimpacts of human activities are on has a responsibility to its clients to inform thembiodiversity. An analytical framework is used of best practices and what the potentialwhich allows for the systematization of these consequences of natural resources managementimpacts across sectors and areas of particular decisions are. This paper helps fulfill thisinterest. responsibility.

Biodiversity Series - Impact Studies v

Executive Summary

Existing parks and protected areas are logging methods, collateral damage, andcornerstones of biodiversity conservation but on silvicultural approaches. Using the richnesstheir own are inadequate to assure the present in both these terms, a framework forcontinued existence of a vast proportion of considering the impacts of logging and othertropical forest biodiversity. As a result, priority forest management activities on the variousmust be given to ensuring that the greatest components and attributes of biodiversity ispossible amount of biodiversity is conserved presented. This framework is, in turn, used tooutside protected areas by altering harvest evaluate the extensive literature coveringpatterns in these landscapes of resource different studies of logging in tropical forests.

extraction. Of all forest uses within tropicalforest regions, logging or timber harvesting, is findings:the most important to influence because not

only is it the most lucrative, it also causes the 1. All consumptive uses affect somemost severe direct and indirect environmental component or attribute of biodiversity,impacts. commonly affecting not only the target

resource but other elements as well.Evaluating the impacts of logging on 2. As a result, only fully protected areas willbiodiversity in tropical forests is not as simple a conserve all components and attributes of

task as many would believe. It depends on a biodiversity.thorough review of the literature and on the 3. Recognizing that all significantbest expert opinion due to the complexities interventions in natural forests havehidden under the seemingly simple rubrics biodiversity impacts, all silvicultural"logging" and "biodiversity." As a first step in decisions necessarily representeffectively analyzing the relationship between compromises. Management for some goodsbiodiversity and logging, it is essential to begin or services necessarily involvesby disaggregating the terms "logging" and management against others."biodiversity." 4. Different intensities and spatial patterns of

timber harvesting, along with othersilvicultural treatments, result in differenteffects on the different components of

"biodiversity" into components (landscapes, biodiversity.ecosystems, communities, species/populations, 5. Some components and attributes ofand genes) and attributes (structure, biodiversity are more sensitive than otherscomposition, and function). It then to forest management activities.disaggregates "logging" by detailing the vast 6. There are some forested areas and somerange of activities subsumed under this term areas within forests, which should never beincluding variation of logging intensities, logged.

Biodiversity Series- Impact Studies vii


7. Biodiversity objectives can and should be areas of high priority for biodiversityestablished within production forests. protection, the persistence of poor logging

8. In many cases the logging itself is not the practices despite substantial efforts in researchmajor cause of biodiversity loss, but rather and training, and the generally slow rate atthe indirect effects, often promoted by the which most loggers are transformingpresence of roads, (for example, hunting, themselves from timber exploiters into forestforest fires, and the likelihood of managers.deforestation) represent the majorenvironmental threats. Nevertheless, even harshly treated forests

maintain more biodiversity than oil palmUnfortunately, due to the complexities hidden plantations, cattle pastures, or cornfields. Fromunder the seemingly simple rubrics "logging" a biodiversity maintenance perspective, naturaland "biodiversity", the answer to the question forest management is preferable to virtually all"Is logging compatible with biodiversity land-use practices other than completeprotection?" can only be the very unsatisfying protection. Forests that are carefully managed"It depends." The paper does not conclude for timber will not replace protected areas aswith uncritical support for sustainable forest storehouses of biodiversity, but they can be anmanagement of timber as a conservation integral component of a conservation strategystrategy. Such an endorsement is unwarranted that encompasses a larger portion of thegiven widespread illegal logging in the tropics, landscape than is likely to be set aside for strictwidespread frontier logging and logging of protection.

viii Environment Department Papers

1 Introduction

Existing parks and protected areas are essential within managed forests should be protected,for biodiversity conservation but inadequate on and which approaches to silviculture to followtheir own to assure the continued existence of within forests used for timber productionthe majority of natural landscapes, ecosystems, should be made on the basis of a wide range ofcommunities, species and genotypes in tropical considerations. Forests differ in theirforests. Even if the.oft-quoted goal of 10-12 biodiversity value, in their capacity to supportpercent protection were attained and the different intensities of silvicultural use, inreserved areas were appropriately located and pressures for conversion to non-forest use, andproperly managed, up to 50 percent of tropical in the abilities of the relevant institutions tospecies would be expected to go extinct during regulate their management. General conceptualthe next few decades (Soule and Sanjayan 1998). approaches to zoning forests for different usesSimilar but often less well documented losses of have been presented recently by various authorsthe other components of biodiversity are including Noble and Dirzo (1997), andexpected. Another way of considering this dire Frumhoff and Losos (1998). Methods forprediction is that if biodiversity outside of integrating conservation functions at differentprotected areas is neglected, thousands of geographical scales were reviewed recently byspecies are likely to disappear. Faced with this Poiani and others (2000). This paper focuses onbleak future, the first priority should be to the forests zoned for timber production. Theincrease the area of forests under strict goals are:protection while at the same time improvingreserve management. Mechanisms should be 1. To contribute to the development of adeveloped to halt road building and commercial heuristic construct for considering the rangelogging in forest wilderness areas as well as in of impacts of forestry activities on tropicalcenters of diversity and endemism. However, forest biodiversity at. the levels ofpromoting more biodiversity-sensitive landscapes, ecosystems, communities,management of forests outside protected areas species, and genes.is of almost equal priority, given the 2. To indicate the topics on which furtherconservation potential of these still vast areas. research will be particularly useful inBiodiversity conservation within forests evaluating the impacts of different forestrymanaged primarily for timber production, for activities on the various components andexample, should be fostered by a combination of attributes of biodiversity.not logging ecologically important areas and by 3. To suggest ways to mitigate the deleteriousemploying biodiversity-sensitive management impacts of forestry activities on tropicalmethods within production areas. forestbiodiversity.

Decisions about which large forest areas should In the search for land-use practices compatiblebe designated for strict protection, which areas with biodiversity maintenance, many

Biodiversity Series - Impact Studies


environmentalists have focused upon logging motivate other conservationists to continue[see Grieser Johns (1997) and Haworth (1999) holding sustainable forest management (SFM)for comprehensive reviews of the environmental as a worthy conservation goal in forests outsideimpacts of logging in tropical forests]. This of protected areas (for example, Dickinson andemphasis is not surprising given that of all others 1996, Chazdon 1998, Poore and othersforest uses, logging is often the most financially 1999, and Whitmore 1999).lucrative and has the most severeenvironmental impacts. The indirect effects of To help elucidate some of the factors uponlogging, particularly increased hunting (for which the compatibility of tropical forestexample, Robinson and others 1999) and the logging and biodiversity protection depend, thisincreased likelihood of deforestation due to paper first attempts to disaggregate the termsimproved access, reviewed by Kaimowitz and "logging" and "biodiversity." The wide range ofAngelsen (1998), have also been highlighted logging intensities, logging methods, collateralrecently. What has emerged from the dust, mud, damage, and silvicultural approacheschainsaw noise, and diesel fumes is the idea appropriate for tropical forests is discussed. Athat conservation of some components of framework for considering the impacts ofbiodiversity could be facilitated by logging and other forest management activitiescollaboration between loggers and on the various components (=landscapes,environmentalists. Some of the latter oppose the ecosystems, communities, species/populations, andidea of promoting better forest management as genes) and attributes (=structure, composition, anda means for achieving overall conservation function) of biodiversity is presented. In thegoals (or at least oppose financial investment in main section of the paper, the components andsuch efforts, Rice and others 1997, Bawa and attributes of biodiversity are used to review theSeidler 1998, Bowles and others 1998). This impacts of logging and other silviculturalopposition notwithstanding, consideration of activities on tropical forests. To promotethe inevitability of logging in much of the readability of the text, much of thetropics, the many constraints on expansion of bibliographical review is presented innature reserves in tropical countries, the appendices organized by the components andchallenges of protecting and managing the attributes of biodiversity. The paper concludesparks already demarcated on paper, sovereignty by suggesting ways to enhance theissues, development needs, and the implicit compatibility of forest management for timberadoption of the "use it or lose it" assumption, and biodiversity maintenance in tropical forests.

2 Environment Department Papers

2 Disaggregating "Biodiversity"

Biodiversity refers to the natural variety and the physical organization or pattern of thevariability among living organisms, the elements. Composition refers to the identity andecological complexes in which they naturally variety of elements in each of the biodiversityoccur, and the ways in which they interact with components. Function refers to ecological andeach other and with the physical environment. evolutionary processes acting among theThis definition and the elucidation below is elements.based upon OTA (1987), Noss (1990) andRedford and Richter (1999). Climate, geology Diversity of the landscape component refers toand physiography all exert considerable regional mosaics of land uses, land forms, andinfluence on broad spatial patterns of biotic ecosystem types. Structure of this componentvariety; local ecosystems and their biological could be described on the basis of the areas ofcomponents are further modified by different habitat patches, through the perimeter-environmental variation (such as local climatic area relations of these habitat patches, or on theand streamflow fluctuations) and ecological basis of interpatch linkages. Landscapeinteractions. This natural variety and variability composition pertains to the identity, distribution,is distinguished from biotic patterns or and proportions of different habitat types.conditions formed under the influence of Landscapefunction refers to issues such as patchhuman-mediated species introductions and persistence and interpatch flows of energy,substantially human-altered environmental species, and other resources.processes and selection regimes (Bailey 1996,Noss and Cooperrider 1994). Diversity of the ecosystem component refers to

In discussions of diversity there is always the interactions between members of a biologicallurking danger of assuming that "more is community and their abiotic environment.better." Were this the case, plowing roads Structure of this component might be measuredthrough mature forests, clearcutting patches, through vegetative biomass and soil structuraland introducing alien species would all be properties. Ecosystem composition refers toreasonable. Although decisions about which features such as biogeochemical standingspecies or community-types are most valuable stocks. Ecosystemjiunction pertains to processesare not straightforward, rarity is one obvious including biogeochemical and hydrologicaldimension that needs to be considered. cycling.

Biological diversity can be measured in terms of Diversity of the community component refers to thedifferent components (landscape, ecosystem, guilds, functional groups, and patch typescommunity, population/species, and genetic), occurring in the same area and stronglyeach of which has structural, compositional, and interacting through trophic and spatial bioticfunctional attributes (Table 1). Structure refers to relationships. Structure of this component

Biodiversity Series - Impact Sthdies 3


Table I Components and attributes of tropical forest biodiversity that might be influenced by logging and

other silvicultural activities

Organized by the components and attributes of biodiversityComponents Struaure Composition FunctionLandscape Size and spatial distribution of Identity, distribution, and Habitat patch persistence and

habitat patches (e.g., seral proportion of habitat types turnover rates; energy flow rates;stage diversity and area); and multi-habitat landscape disturbance processes (e.g., extent,physiognomy; perimeter-area types; collective patterns of frequency, and intensity of fires);relations; patch juxtaposition species distributions human land use trends; erosionand connectivity; fragmentation rates; geomorphic and hydrologic

processes

Ecosystem Soil (substrate) characteristics; Biogeochemical stocks; Biogeochemical and hydrologicalvegetation biomass, basal area lifeform proportions cycling; energy flux; productivity;and vertical complexity, density flows of species between patches;and distribution of snags and local climate impactsfallen logs

Community Foliage density and layering; Relative abundance of Patch dynamics and othercanopy openness and gap species and guilds; richness successional processes;proportions; trophic and food and diversity indices; colonization and extinction rates;web structures proportions of endemic, pollination, herbivory, parasitism,

exotic, threatened, and seed dispersal and predation rates;endangered species; phenologyproportions of specialists vs.generalists

Speciesl Sex and age/size ratios; range Species abundance Demographic processes (e.g.,Population and dispersion; infraspecific distributions, biomass, or survivorship, fertility, recruitment,

morphological variation density; frequency; and dispersal); growth rates;importance or cover value phenology

6enetic Effective population size; Allelic diversity; presence of Gene flow; inbreeding depression;heterozygosity; polymorphisms; rare alleles; frequency of rates of outbreeding, genetic driftgeneration overlap; heritability deleterious alletes and mutation; selection intensity;

dysgenic selection

Note: Modified from Noss (1990) and Redford and Richter (1999).

includes consideration of vegetative be measured through population age structurephysiognomy and trophic structure. or species abundance distributions. Species/Community composition refers to relative population composition pertains to whichabundances of species and guilds. Community particular species are present. Function of thisfunctions include flows between patch types, component refers to demographic processesdisturbance regimes (such as fires and floods), such as recruitment and death.successional processes, and species interactions.

Diversity of the genetic component refers to theDiversity of the species/population component refers variability within a species, as measured by theto the variety of living species and their variation in genes within a particular species,component populations at the local, regional, or subspecies, or population. Structure of thisglobal scale. Structure of this component might component can be expressed on the basis of


Disaggregating "Biodiversity"

heterozygosity or genetic distances between and in what proportions. Genetic functions canpopulations in different patches (that is, be expressed on the basis of gene flow, geneticmetapopulation genetic structure). Genetic drift, or loss of allelic diversity in small, isolatedcomposition refers to which alleles are present populations.

Biodiversity Series - Impact Studies 5

3 Disaggregating "Logging"

When properly planned and conducted, logging about the compatibility of logging with(=timber harvesting) is an integral component biodiversity conservation are complicatedof forest management systems designed to because logging is carried out over a huge rangepromote sustained timber yields (STY), or the of intensities, using a variety of techniquesmore all-encompassing goal of sustainable which may be applied carefully or in ways thatforest management (SFM). Unfortunately, result in a great deal of avoidable damage. Thelogging in tropical forests all-too-often following sections focus on the issues ofrepresents a timber "mining" activity carried harvesting intensities, yarding methods (=howout without regard for the renewability of this timber is extracted from the stump to haulnatural resource (for example, Putz and others roads), and ways of reducing logging damage.2000). Other silvicultural treatments designed to A brief overview of other silviculturalpromote sustainability are often prescribed but treatments used in timber stand management isare rarely applied. Due mostly to the desire to also provided.obtain voluntary third-party certification ofgood management from the Forest Stewardship Logging intensitiesCouncil (FSC), the transition from forest mining Trying to conclude anything about theto forest management has finally started to Try ity oflogging aboutetheoccur in some areas in the tropics (Nittler and compatibility of logging and biodiversityNash 1999). Despite this progress, even within maintenance is made complicated by the widecertified forests there are questions about how range of logging intensities, yarding methods,to most effectively and efficiently minimize the and accompanying forest management practicesdeleterious environmental impacts of logging to which tropical forests are subjected. Theand other silvicultural activities. This paper simple observation that logging intensities spanaddresses many of these questions by reviewing more than two orders of magnitude (<1 m 3 /hathe state of knowledge about biodiversity to >100 m 3 /ha) illustrates the challenge ofmaintenance in exploited and managed tropical generalizing (Figure 1).forests.

Even within the same forest management unit,It is critical to recognize that forest interventions logging intensities vary greatly at differentof all types, from harvesting of fruits for home spatial scales. At a small scale (1-10 ha), theconsumption to clearcutting for timber, all have typical aggregated distributions of tropical treesimpacts on forests that need to be understood (Hubbell 1979) leads to locally severe loggingand often deserve mitigation (Peters 1996). impacts unless harvesting controls areNevertheless, logging is often the most implemented (that is, "tree-marking rules" aredamaging and generally the most financially followed, Uhl and Vieira 1989, Crome andlucrative of such forest interventions (Pearce others 1992, Cannon and others 1994). Theand others 1999). Unfortunately, discussions localized but severe direct impacts of roads, log



landings, and skid trails hardly need to be eastern portions of Amazonian Brazil, it is likelyemphasized (Guariguata and Dupuy 1997). At a that 30-50 m3 of 20-30 species would beslightly larger scale (10-100 ha), stands vary in harvested Uohns and others 1996).stocking of commercial species and in theiraccessibility due to terrain or edaphic factors. The substantial number of studies conducted onWhere logging is carried out in areas designated the impacts of logging in tropical forests allfor each year of management (=annual coupes), concluded that soil impacts and damage to thelogging impacts tend to be aggregated at larger residual forest all increase with increasingscales. logging intensity (Ewel and Conde 1976, Sist

and others 1998a). Proportions of both soil andLogging intensities also vary over time, tending residual trees damaged by logging range from 5to increase with local timber shortages, to 50 percent, depending on harvestingimproved access, and greater willingness of intensity, yarding method, and the care withmarkets to accept lesser-known species which the operations are carried out.(Plumptre 1996). For example, in a remote part Interpretation of data pertaining to theof the Bolivian Amazon loggers may harvest an relationship between logging intensity andaverage of only 0.3 m 3 /ha of 1-3 species residual stand damage is complicated by(Gullison and Hardner 1993) whereas in concomitant change in residual stand density; atsimilarly stocked stands in the more accessible the extreme, there is no residual stand in

Figure I Logging intensities (m3/ha) for tropical forests. In most of these studies, as in most logging areas inthe tropics, felling was with chainsaws and yarding with bulldozers or articulated skidders with rubber tires.

< I rn/ha 50 m 3/ha 00 m 3 /ha 150 m 3/ha

Bolivia Venezuela Indonesia Malaysia(Gullison and Hardner 1993) (Kammesheidt 1998) (Bertault and Sist 1997) (Pinard and Putz 1996)

Suriname Costa Rica Philippines

(Hendrison 1990) (Webb 1998) (Nicholson 1979)

Venezuela

(Mason 1996)

Australia

(Cromeet al. 1992)

Brazil Malaysia

Oohns et al. 1996) (Pinard and Putz 1996)

Australia

(Crome et al. 1997)

Uganda(Chapman and Chapman 1997)

8 Environment Departnent Papers

Disaggregating "Logging"

clearcuts. Further complicating assumptions at the landscape, ecosystem, community,about logging damage is the fact that few population/species, and genetic levels variestropical forests are logged (or burned) only once greatly along the continuum of technological(Box 1). sophistication of yarding methods that stretches

from manual extraction to the use of helicoptersLog yarding methods (Figure 2). Note that Figure 2 hides a great deal

In this paper, particular attention is paid to the of relevant variation. In particular, attempts toyarding phase of the timber harvesting process include another dimension expressing yardingbecause much of the direct damage to tropical costs (per cubic meter yarded to the roadside)forest caused by logging occurs while logs are have so far failed due to the multitude of factorsbeing extracted from the stump to roads or that need to be considered, including laborriversides from which they are then hauled or costs, technical capacity, and discount rates,towed out of the forest. Yarding methods along with the values assigned to future harvestutilized in tropical forests range in technological yields, non-timber forest products, biodiversitysophistication, the collateral damages with protection, and ecosystem services.which they are associated, and in yarding costs(Conway 1982). Accurate cost figures for Yarding can be carried out in an environmen-yarding are difficult to obtain and problematic tally/silviculturally sensitive manner, or can beto calculate (for example, should impacts on extremely destructive. The rankings offuture timber yields be included, and, if so, at environmental impacts on Figure 2 are justwhat discount rate?). For the same volume of suggestions of the typical amounts of damagetimber yarded, the range in biodiversity impacts associated with different yarding techniques.

Box 1Few tropical forests are logged or burned only once

Logging and wildfires in tropical forests are causally linked (Holdsworth and Uhl 1997) and also share thecharacteristic of being self-promoting processes. Although the environmental damage resulting from unplannedlogging of primary forest by untrained crews is justifiably receiving attention from researchers and policy-makers, few logged stands are allowed to recover for the full cutting cycle or rotation stipulated in their man-agement plans. Instead, forests are repeatedly entered by loggers who sequentially 'high-grade" the best re-maining timber. Although the costs of road building are substantial, the first cut is generally the most lucrative.As more timber species enter commercial markets, and mills begin to accept smaller and lower quality logs,incentives for multiple entry logging increase. The same logging firms are sometimes involved in a series ofentries into the same forest, but more often firms with lower operating costs and smaller equipment takeadvantage of the increased access provided during the first harvest. A familiar adage in Amazonia is "ma-hogany builds the roads." Reliable data on frequencies of multiple entry logging, either legal due to waiversissued by governmental agencies or illegal, are apparently rare, but the process is unquestionably common-place.

As with multiple entry logging, wildfires seldom occur only once (Peres 1999, Cochrane and Schulze 1999). Inforests that are not naturally maintained by fire, the first fire opens the canopy and thereby subjects the under-story to rapid drying. Fuel mass in the understory is augmented by trees killed by the first fire, and by grassesand other plants that regenerate under conditions of reduced competition. The resulting fire frequencies farexceed the historical rates. In the eastern Amazon, for example, fire frequencies in Paragominas have recentlydoubled and now occur far too frequently to allow forest recovery. Human made savannas and grasslandsalong with severely degraded forests due to frequent fires are becoming more the rule than the exceptionthroughout much of the wet and moist tropics. On the basis of either the area affected or the magnitude ofimpacts, the direct damages attributable to tropical forestry are minor compared to those of wildfires.



Figure 2 Generalized ranges of direct biodiversity impacts of timber yarding methods used for tropicalforest logging as a function of level of technological sophistication required (assumes equal volumes of timberyarded). For mechanized ground-based yarding operations, conventional (non-RIL) and reduced-impactlogging (RIL) impacts are contrasted.

Severe

M odest

Low (;reatTechnological Sophistication

For ground-based yarding, using the smallest bulldozer yarding, especially at high intensitiesyarding equipment possible contributes to on steep slopes logged during wet weather byreducing the deleterious impacts of logging, untrained crews is well known, but bulldozersW.Ahich yarding equipment is used is important, still yard much of the timber in commercialbut so is the care with which yarding operations logging areas in the tropics.are carried out, as indicated by the contrastsbetween conventional and reduced-impact With the loss of forest in accessible areas inlogging (RIL) on Figure 2. Unfortunately, much of the tropics, logging is increasinglyalthough the silvicultural, environmental, and being relegated to flooded, steep, rocky, oreconomic benefits of planning of log extraction otherwise adverse terrain. Because groundroutes have been recognized for many decades based yarding from such sites can be(see Putz and others 2000 for a review), well prohibitively expensive, they have often beenplanned logging operations are still the left as unlogged refugia within harvested areas.exception in tropical forests. Their status as refuges is jeopardized by

helicopter yarding, because helicopters can yardMost destructive yarding in tropical forests is timber from even the most adverse sites.carried out with bulldozers (=crawler tractors). Obtaining timber from these sites is becomingBulldozers are excellent devices for constructing more cost effective under some conditions.roads but are unfortunately versatile enough to Although areas from which timber is harvestedyard timber as well. The excessive damage to by helicopters are not dissected by skid trails,soils and residual trees during conventional haul roads are still needed, and with them, all



the problems associated with increased access. regeneration, the second cut releases theAn equally important concern about helicopter established seedlings and saplings. There areyarding is that areas traditionally avoided by innumerable variations on the themes ofloggers are rendered accessible and are likely to monocyclic and polycyclic harvesting, and eachbe harvested. Because helicopters leave no is appropriate under different conditions and inobvious trails, it is going to be very challenging forests for which there are different silviculturalto monitor their harvesting impacts. goals (Lamprecht 1989). Even within the same

forest, the silviculturally most appropriateLogging and other silvicultural treatments harvesting regime sometimes can change over

Logging can be either a cause of a great deal of distances of less than 100 m (Pinard and othersavoidable damage or one of a series of 1999).silvicultural treatments designed to promote theregeneration and growth of commercial timber The most common method attempted forspecies while protecting ecosystem services and controlling timber harvesting in tropical forestsbiodiversity. In logging areas where sustained is to simply set a minimum stem diameter foryield of timber is a priority, various silvicultural felling. Although theoretically easy totreatments can be used in combination with the implement and monitor, minimum diameterappropriate logging regime to promote the rules are often inimical to achieving silviculturalregeneration or growth of commercial species. goals. The problem with this system is obviousCarrying out silvicultural treatments in where minimum diameter limits are set belowconjunction with logging reduces their cost the sizes at which trees start to reproducewhile simultaneously reinforcing the idea that (Appanah and Manof 1991, Plumptre 1995).logging itself can be silviculturally useful. Minimum diameter rules also do not prevent

harvesting of clusters of trees and thereby

Silviculturally appropriate harvesting creating silviculturally unsatisfactory conditionsprescriptions (from a timber stand management such as where commercial species are favoredperspective) run the full gamut from single tree by small canopy gaps or vines proliferate inselection to clearcutting (Smith and others large ones.1997). For forests with ample stocks of trees ofall sizes of the commercial species (that is, Logging is often the most severe of silviculturalnegative exponential size-class frequency interventions, but there are other prescriptionsdistributions), "polycyclic" (=uneven aged) designed to increase the stocking of commercialmethods such as single tree and group selection tree species, or to increase the growth of treesmethods are generally suitable. In such a forest, already present. Retaining seed trees inthe next crop is derived from the mixture of harvested stands is one possible way to increasetrees of intermediate size (for example, 20-40 stocking, but for species that require mineralcm dbh) at the time of first cutting. In contrast, soil seed beds or minimal competition forat the time of the initial harvest the trees in the germination, establishment, and subsequentnext crop in "monocyclic" (=even-aged) systems growth, seed tree retention needs to beare seeds, seedlings, or saplings. Clearcutting is combined with various other treatments. Seedthe most obvious example of a monocyclic beds can be modified and competition can besystem, but in "shelterwood management" a reduced by controlled burning, mechanicalsingle-aged stand develops after two stages of scarification, or herbiciding plants competingharvesting. The first shelterwood harvest opens with seedlings of the crop species. Wherethe canopy and otherwise stimulates natural regeneration fails, or where particularly

Biodiversity Series -Impact Stutdies 11


high stocking levels are desired, many foresters Reducing the impacts of logging and otherhave tried planting seedlings of commercial silvicultural treatmentsspecies in gaps or along lines cleared through Substantial attention has been given recently tothe forest (see Box 2). For stands in which Suced-ial loggin has Box 3ie Most oregeneration of the commercial species is "reduced-impact logging" (RIL, Box 3). Most ofalready established, various thinning and weed the practices in the various RIL guidelines thatcontrol treatments are often prescribed to have been promulgated of late have long beenaccelerate tree growth and otherwise for "stand recognized as being environmentally sound andimprovement." Thinning around potential crop silviculturally appropriate (Bryant 1914). Fulltrees, often referred to by tropical foresters as application of RIL techniques would represent a"liberation thinning," and vine cutting are two major step towards sustainable forestcommonly prescribed but less commonly management (SFM), but RIL alone does notapplied silvicultural treatments. In guarantee sustainability. Especially where treeexperimental areas where liberation treatments species being harvested only regenerate in largehave been applied to enhance volume clearings, the required silviculturalincrements of commercial species, treatments interventions to assure sustained yield of theare often prescribed at 10-year or more frequent same species may often be substantial (forintervals (de Graaf and others 1999). As in the example, mimicking the impacts of slash-and-case of logging, all of these other silvicultural burn agriculture or hurricanes followed by fires,treatments have impacts on biodiversity, but Snook (1996), Fredericksen (1998), Dickinsonthey have been much less well studied. and Whigham (1999), Pinard and others (1999),

Box 2Enrichment planting

Despite scarcity of successes and millions of dollars wasted, enrichment planting in gaps or along cleared linescontinues to be invoked as a way of restoring the commercial timber production potential of severely degradedforests. The principal problem with enrichment planting is failure to tend the out-planted seedlings (Dawkins1961, Dawkins & Philip 1998). Admittedly there are cases where few silvicultural options remain. Unfortu-nately, enrichment planting is often utilized in forests that should not need such an expensive intervention.Furthermore, it is often not recognized that enrichment planting as often applied results in conversion ofnatural forests into plantations. Mason and Thiollay (in press) compared the impacts of enrichment plantingwith conventional selective logging in Venezuela and found the former to have greater negative impacts onbirds. With these caveats issued, a description of a large-scale enrichment planting project in Sabah, Malaysiamay be useful because the project implementers are avoiding some of the pitfalls of this technique and aretrying to mitigate some of its deleterious environmental impacts.

Funds from the FACE (Forests Absorbing Carbon Dioxide Emissions) Foundation of The Netherlands, RakyatBerjaya (a subsidiary of the Innoprise Foundation) have been used to plant nursery grown seedlings of com-mercial species in several thousand hectares of forests degraded by extremely intensive and poorly controlledlogging in Sabah, Malaysia. The project has developed rapidly since its inception in 1992. Contract plantersare now trained in dendrology so that they can recognize natural regeneration, and are paid for its retention atthe same rate as for planted seedlings. Planters are also responsible for tending operations and are not paid forseedlings that do not survive 3 years. Site matching of species has also improved, as have nursery techniquesfor tending wildlings (=seedlings extracted from the forest) and raising large numbers of seedlings at rela-tively low cost. Finally, to promote retention of wildlife in the planting area, seedlings of fleshy- fruited treesare planted along with the mostly wind dispersed timber species in the Dipterocarpaceae. When the plantedstands are ready to harvest in 50 or so years, the concessionaire hopes to harvest 50-100 trees per hectare, anintensity tantamount to clearcutting but perhaps preferable to the forest conversion to pulpwood plantationoption that has been adopted in much of the region.



Box3Is reduced-impact logging (RIL) cheaper?

Many people believe that RIL has been proven cheaper than conventional logging (CL) and are therefore per-plexed at the lack of its adoption by loggers. Adoption of RIL techniques is of particular importance in thetropics where few countries have regulations that are both explicit enough and well enough enforced to pre-vent exploitative harvesting.

Numerous studies over the past decades have shown that by planning skid trails and directional felling tofacilitate yarding, logging damage can be substantially reduced (Bryant 1914, Nicholson 1958, Redhead 1960,Fox 1968, Nicholson 1979, Ewel and Conde 1980, Hendrison 1990, Johns and others 1996, Pinard and Putz 1996,Blate 1997, Elias 1997, Winkler 1997, Uhl and others 1997, Haworth 1999). Several experimental plot-basedstudies have demonstrated that due primarily to reduced yarding costs, such straightforward improvementsin logging methods also translate into direct financial benefits to the loggers (Marn and Jonkers 1981, de Graaf1986, Malvas 1987, Jonkers 1987, Hendrison 1990, Gerwing and others 1996, Bertault and Sist 1997, Barreto andothers 1998, Holmes and others 1999, Boltz 1999). If RIL is cheaper than CL per cubic meter yarded to theroadside, then why haven't loggers spontaneously adopted RIL techniques out of enlightened self interest? Apartial answer to this question may be that under normal operating conditions, at industrial scales, and espe-cially on adverse terrain in wet forests, RIL may not always be cheaper (Putz and others 2000, Hammond andothers 2000). Data on the comparative costs of RIL and CL from the "Reduced-Impact Logging as a CarbonOffset Project" in Sabah, Malaysia may serve to elucidate this issue. Tay (1999) and Healey and others (in press)reported that the financial profits from logging were substantially lower in a 450 hectare area harvested ac-cording to RIL guidelines than in a comparable area subjected to CL. The principal reason for lower profitabil-ity of RIL was the reduction in yield caused by reductions in the proportion of the area logged due to restric-tions on bulldozer access to steep slopes. Despite regulations against timber yarding from steep slopes inSabah, the practice is commonplace and loggers consider the timber foregone when RIL guidelines are fol-lowed as lost profits and thus do not spontaneously adopt RIL out of enlightened self interest. These findingsindicate that the issue of cost effectiveness of RIL under adverse conditions deserves scrutiny and that loggersnot using RIL techniques may not be acting in a financially irrational manner.

In contrast to the apparent situation regarding RIL adoption in Southeast Asia, large vertically integratedforestry companies in Brazil have begun to invest heavily in RIL apparently out of enlightened self-interest.Although there is an additional incentive for adoption of more environmentally friendly logging in the form ofbetter enforcement of regulations governing forest management operations, it appears that some companieshave been convinced by the work of Baretto and others (1998), Holmes and others (1999), and others that their Iprofits will increase if they adopt more efficient (and resource friendly) practices. Loggers in the region are alsoapplying RIL techniques in response to an increase in demand for timber certified by the Forest StewardshipCouncil.

Given the differences in the results of comparative studies on the financial profitability of different loggingtechniques, adoption of RIL techniques under some conditions may require either subsidies (such as carbonoffset funds) or stricter regulations with better enforcement. The conditions under which incentives for RILadoption are needed, and the best form and magnitude of these incentives are yet to be determined.

Fredericksen and Mostacedo (2000). This reduced as well, by proper design, construction,silvicultural challenge notwithstanding, careful and maintenance of road networks. Much of theplanning and implementation of harvesting cost of harvesting timber and a large proportionguidelines would represent a big step towards of the hydrological damage (for example,sustainable forest management. stream sedimentation) due to logging is

associated with roads (Bruijnzeel 1992). ForFor all yarding methods, logging damage can be ground-based yarding, efficient skid trailsubstantially reduced, and logging costs layouts are also essential for reducing logging

Biodiversity Series -Impact Studies 13


damage and increasing yarding efficiency, but environmental impacts, adhering to RILimproper road siting often restricts skid trails to guidelines has advantages regardless ofinappropriate places. Although the required whether the forest is allowed to regenerate or isdensity of roads is lower where aerial extraction replaced by an oil palm plantation or a maizetechniques are used (such as skyline and field (Congdon and Herbohn 1993, Nussbaumhelicopter yarding), roads are still needed and and others 1995, Pinard and others 1996).their locations can greatly influence loggingcosts and environmental damage. Guidelines The impacts of other silvicultural treatments onfor road construction are abundantly available biodiversity (such as thinning and vine-cutting)and are well outlined in the FAO Model Code of depend on the intensity with which they areForest Harvesting Practices (Dykstra and applied and on the proper designation of areasHeinrich 1996). Unfortunately, forest deemed inappropriate for stand "improve-engineering standards in most tropical logging ment." For example, vinecutting can enhanceareas are extremely low and there are too few tree growth but undoubtedly has negativeexperienced forest engineers involved in most impacts on a wide variety of animals (Putz andtropical logging operations. It is important to others in press). Both biodiversity impacts andnote that because soil damage due to poor skid labor costs of vine cutting depend on whethertrail design or improper use, for example, only selected future crop trees are liberated orreduces productivity, increases surface erosion, vine cutting is carried out as a blanketand has various other deleterious prescription.


Imnpacts of Forest Managementon Biodiversity

Background exploitation (Coomes 1995, Homma 1992). Thisahistorical and wishful thinking is extremely

Human activities are highly variable in their angerocau a llows its adhrentltinfluence on the components and attributes of dneosbcuei losisahrnstbinfleer ony theompone ant thattribults of believe that there exist easy, cost-free solutionsbiodiversity. Any human activity that results intmxliaino h lntsubstantial resource extraction or modification t e

will always entail significant, often unknown, As societal concerns about the fates of tropicaland almost always unappreciated consequences forests increase and human demands on forestsfor one or more biodiversity components,primarily by redirecting matter and energy change, so should the ways in which they areflows. The cumulative redirection is enormous silviculturally treated. For example, a few

decades back when the primary component ofat the planetary scale as three examples sustainability of interest to most forest decision-illustrate: 1) Vitousek and others (1997)calculated that 40 percent of the Earth's makers was sustained timber yields (STY), itterrestrial primnary productivity is being was often recommended that logging beappropriated by humans, 2) 25 to 35 percent of followed by silvicultural stand "improvement"the primary productivity of continental shelf treatments such as poison girdling of non-marine ecosystems is consumed by humans commercial trees, for a historical review see(Roberts 1997), and 3) Postel and others (1996) Dawkins and Philip (1998). Unfortunately, fewreport that humans now appropriate 26 percent of the tens of thousands of hectares of tropicalof total evapotranspiration and use 54 percent forests that were treated according to theof all runoff in rivers, lakes, and other accessible various silvicultural systems used in the 1950ssources of water. (for example, the Malayan Uniform System and

the Tropical Shelterwood System) remain, most

Despite these statistics on current human having already been logged again, converted toimpacts and the observations of the long-term oil palm plantations, or otherwise lost.impacts of previous generations of our species Fortunately, there is now evidence from a(Denevan 1992), many in the conservation and lowland dipterocarp forest in Malaysia that atsustainable development community still least the Malayan Uniform System (MUS) couldmaintain it is possible to both use and preserve achieve its silvicultural goals (Lee and othersbiodiversity (Huston 1993) with no costs to 1998) with mixed impacts on biodiversity,either side. This claim is made regardless of a depending on the taxon in question. The foresthistory of human over-exploitation of resources treated by MUS and then studied 45 years laterthat began in prehistory (Goudie 1990) and is was, as intended, enriched in commercialmanifested most recently in the negative effects timber trees, but also maintained much of theof tropical logging (Bawa and Seidler 1998, fauna and flora of primary forest. More studiesFrumhoff 1995) and non-timber forest product of this sort are needed, and they need to be



better circulated so that more people will realize hydrologic processes. The most severe impactsthat at least "qualified" successes in tropical described in this section, however, result fromsilviculture are attainable. indirect consequences of logging such as

increased access to remote areas, fragmentation,In the following sections (4.2-4.6) the impacts of and altered fire regimes.logging and other silvicultural treatments on thecomponents and attributes of biodiversity using Structure: The size and spatial distribution of

the framework elaborated in section 2.0 (see tropical forest patches and the juxtaposition andTable 1) are outlined; details are provided in the connectivity of different forest patches acrossappendices. Summarizing the impacts of the necape are most patche acrossforestry activities on biodiversity in tropical the landscape are most affected by ite indirectforests is an effort fraught with problems in impacts of logging. One of these impacts-large part due to their immense diversity. Even increased access to humans-is oftenat the species level, the diversity is difficult to deleterious. Partcularly when logging roadsimagine and each of the literally millions of penetrate far into the forest frontier in countriesspecies in tropical forests responds to different where there are numerous potential forestlogging impacts in distinct ways. While some colonists, logging is almost invariablygeneral response patterns are obvious, and accompanied by increased hunting pressureothers have emerged from field research, the (Robinson and others 1999, Robinson andidiosyncrasies and apparent inconsistencies of Bennett 2000) and is often followed byspecies responses need to be recognized. For deforestation as lands are cleared for agricultureexample, chimpanzee (Pan troglodytes) (Kaimowitz and Angelsen 1998).populations have been reported to increase(Howard 1991, Hashimoto 1995), decrease Another indirect impact of logging on this(White 1992), and not respond to logging attribute is fragmentation of previously

(Plumptre and Reynolds 1994, see Appendix contiguous or otherwise connected forestVI). In contrast, studies of terrestrial and bark- patches. The resulting forest fragments,gleaning insectivorous birds have consistently however, are typicaly not completely isolatedreported negative impacts of logging (see for all species for all time. For example, wideAppendix IV). Many more examples of this sort lor roads may time. Forossableare discussed briefly below, and both cosset logging roads may represent uncrossablearedisconsistent pattefly below,erge. consistent barriers for some forest interior species butand inconsistent patterns emerge. roadsides with secondary vegetation attract

Landscape impacts (see Appendix I) many large ungulates where they are moreeasily hunted (Robinson and Bennett (2000) in

Logging affects the landscape component ofSaak,Mlyi)Whtelogdsnsarbiodiersit by cangig lan form andSarawak, Malaysia). Whether loggred stands arebiodivrsity y chaging lnd fors andinterspersed within s ecies-rich forest or in a

ecosystem types across large geographic areas p p(Box 4). Logging shifts the regional mosaic of low diversity landscape dominated, forland uses. Although the landscape component example, by pulpwood plantations, alsoof biodiversity is the least sensitive to logging, influences long-term species maintenance.changes in the size, spatial distribution, and Furthermore, even small unlogged patchesconnectivity of habitat patches across the within harvest areas can serve as sourcelandscape occur especially as the intensity of populations for some species after logging. Themanagement interventions increases. These degree of fragmentation depends on whetherchanges in the habitat mosaic alter species logging is dispersed over large areas, or isdistribution patterns, forest turnover rates, and concentrated in small areas (Figure 3). Where


Impacts of Forest Management on Biodiversity

Box4The critical role of production forests in maintaining biodiversity in the tropics

Tropical rainforests harbor approximately 50 percent of all terrestrial biodiversity and much of that biodiversityoccurs in the lowland forests which are most accessible for, and thereby most threatened by, logging andagricultural conversion. In Peninsular Malaysia, for example more than 50 percent of all mammal species occurbelow 350 m and a startling 80 percent occur below 650 m (Stevens 1968, MacKinnon and others 1996). World-wide tropical forest loss is estimated as at least 17 million hectares/yr, an area the size of Cambodia (FAO1993). Dramatic as it is, this global total is probably a gross underestimate given that recent figures show thatIndonesia alone has lost 18 million hectares of tropical forests between 1985 and 1997 in just three of the majorOuter Islands-Kalimantan, Sumatra and Sulawesi. Most of this forest loss has occurred in lowland forest andlogging has played a major role in that destruction. In many areas forests have been cleared and converted foragriculture, plantations and transmigration. However, it is not logging activities per se that have caused forestand biodiversity loss but poor concession management and new access along logging roads. These factorshave allowed shifting farmers and hunters to colonize and clear logged areas. Moreover, areas that have beenlogged (whether legally or illegally) are more vulnerable to wild fires during El Nifio years; there is no doubtthat poor logging practices contributed to the great Indonesian fires in 1998 when 5 million hectares of forest inKalimantan burned, an ecological, economic and social disaster.

It is not just the reduction in total area of natural habitat that concerns conservationists, it is also the fact thatremaining habitat is being broken into ever smaller fragments within which species' populations are no longerviable. As habitats become more fragmented by clearance along new roads, protected areas will increasinglybecome "islands" and more and more species populations will be fated for local extinction. Fragmentation isparticularly serious because few protected areas still cover a full range of altitudinal habitats as large areas oflowland forests, the most species-rich habitats and prime habitat for many large and wide-ranging mammals,have been excised from designated protected areas for logging (such as Kerinci, and Gunung Leuser NationalParks in Sumatra). For Gunong Leuser National Park, for example, the main elephant, orangutan and tigerpopulations occur in the lower-lying production forests outside present park boundaries. Even more alarmingis the recent increase in logging and other illegal activities within the boundaries of several National parks inIndonesia.

The loss of bird species on Java is an indicator of what can be expected in Borneo and other large islands asforests are cut and fragmented. Studies of forest bird distribution shows that whereas in Borneo, Sumatra, andNew Guinea, maximum avian species richness is still found in lowland forests and species numbers decreasewith altitude, Java is atypical in having a depauperate avian fauna in the hill zone between 300 and 15OOrn.This pattern is interpreted as a result of long term deforestation since some predominantly lowland specieshave failed to survive in hill forests because they have been cut off from lower altitude populations which werea source of colonizers. Families of large birds such as malkohas have lost proportionally more species thanfamilies of small birds such as flowerpeckers. Moreover, Java has lost more species which are exclusive tolowland rainforests than species which can occupy secondary habitats, forest edge or open habitats. Smallforest patches have lost more species than larger blocks, with extinction rates as high as 80 percent in 10-40hectare plots compared to rates of 25 percent for areas over 10,000 hectares. These results have importantimplications for reserve design, forest management and biodiversity conservation. They emphasize thatforestsmust be maintained asforests and that reserves must be large, cover a wide altitudinal range and be connected bycorridors of natural habitats. This necessitates a landscape approach to biodiversity conservation by manag-ing production forests adjacent to core protected areas to maintain both permanent forest cover and biodiversityso that production forests become buffer zones that effectively extend and supplement the conservation estate(MacKinnon and others 1996, MacKinnon and Phillipps 1993).

preservation of forest interior biodiversity is the conservation biologists (Noble and Dirzo 1997).

priority, concentrating logging in small areas is Fortunately, due to associated cost savings,

generally the pattern recommended by concentration of logging activities is one of the



Figure 3 Some impacts of logging on biodiversity as a function of distribution of logging activities (percent ofarea logged) and logging intensity (m3/ha of timber harvested)

Concentrated Damage Worst Case for Biodiversity

.t .to Moderate Yield Maximum Yield

Large Area Impact-Free Small Area Impact-Free

DoC Low Impact Dispersed Damage

J ? Minimum Yield Moderate Yield

Large Area Impact-Free Small Area Impact-Free

Low High

Area Logged (percentage)

steps towards improved forest management improved access provided by logging roadsthat loggers may find acceptable. indirectly fosters post-logging habitat changes

by human forest colonizers, weeds, andThe impacts of logging and other timber stand wildfires.management activities on landscape structureare minimized when plantation products are Setting aside reserves within logging areas mayused in place of those from natural forest. mitigate some of the deleterious impacts ofOpting for this so-called "New Zealand logging and other silvicultural treatments. TheSolution" (Hunter 1998) is not currently an specific location of reserves substantiallyoption likely to be exercised in many tropical influences their value in biodiversitycountries. Nevertheless, as forests dwindle and conservation. Optimally, the full range ofeconomies grow (such as in Thailand, Malaysia, landscape features and habitats should beChile, and South Africa), this solution will represented within protected areas.become more viable.

Function: Logging may markedly alter severalComposition: Logging activities may directly landscape level ecological processes subsumedand indirectly affect the identity, distribution, under the functional attribute of the landscapeand proportion of habitat types in tropical component of biodiversity. For example,forests. Forestry may directly affect composition logging roads, and activities associated withof the landscape component of biodiversity by their construction, can greatly influence theintentional creation of new types of habitats permanence of the forest fragments they create(such as forests converted into plantations). by altering landscape level disturbance regimes.Furthermore, if silvicultural objectives are In large part, disturbance is altered becauseuniform across the landscape, inter-stand roads and skid trails provide ready access to thediversity is sacrificed by widespread forest for both colonists and fire (see below).application of the same stand "improvement" High intensity and widespread logging,treatments. Perhaps most importantly, especially if not carefully controlled, also



influences hydrological processes at all levels improvements in relevant remote-sensingperhaps including the regional climate. Where methods, the impacts of the understory burnslogging roads are wide and logging intensities typical for tropical forest fires are substantial.are high, landscape level movements of animals Especially in forests that have not burned forcan be disrupted (Goosem 1997), as can gene many decades to centuries, the effects of even aflow in plants when pollinators are restricted to single understory burn are great, even if theyisolated fragments by inhospitable are not fully realized for many years. Typicallysurroundings. It should be noted, however, that small trees are killed whereas large trees oftenthe impacts of roads depends on where and receive only minor basal damage. Unfortu-how they are constructed, and change with time nately, basal damage exposes trees to woodas the road and its margins mature (Lugo and rotting organisms; a high incidence of heart rotGucinski 2000). is typical of forests that burn at low intensities

at infrequent intervals (F. E. Putz, pers. obs.).

In this section the emphasis is on the impact of Elevated rates of tree mortality rates for manyfires on the functional attributes of landscapes years post-fire are also characteristic in seldom-in full recognition of the importance of fires to burned forests. Such long-term data are difficultall components and attributes of tropical forest to obtain because accumulation of fuel in thebiodiversity. Although fires have long played form of fallen branches as well as post-firesubstantial roles in the ecology of tropical proliferation of palms, grasses, and other fire-forests throughout the world (Goldammer 1990, carrying plants render forests very fire prone.Saldarriaga and West 1986), wildfires as Surprisingly, the effects of tropical forest fires onexemplified by the recent Indonesian fires have biodiversity have not been extensively studiedrecently increased in frequency, extent, and (Leighton and Wirawan, 1986).

intensity in part due to widespread logging Ecosystem impacts (see Appendix II)(Cochrane and Schulze 1999, Cochrane andothers 1999). Canopy opening due to timber The deleterious ecosystem-level impacts ofharvesting operations increases the rate of forest logging on tropical forests are widespread,drying and thereby increases inflammability substantial, enduring, and well studiedeven in characteristically wet forests and (especially compared to the landscape andswamps (Holdsworth and Uhl 1997). Perhaps genetic components). The ecosystem componentequally importantly, vegetation proliferation of biodiversity is somewhat more sensitive toalong logging roads and skid trails greatly logging impacts than the landscape componentenhances fire penetration into forest interiors in part because management activities areeven where logging damage is slight or non- usually implemented at this scale. In contrast toexistent. Whether or not the extensive forest the landscape component, most ecosystem-levelfires that have recently become common can be impacts are a direct consequence of loggingindirectly attributed to logging, it is clear that activities. Logging purposely removes biomassfire damage often exceeds logging damage in from ecosystems, but it also alters their verticalmany tropical countries. In Bolivia in 1999, for complexity and soil characteristics. Dependingexample, fires burned an estimated 20,000 km2 on the silvicultural objectives, changes inwhereas logging was carried out in perhaps structural heterogeneity may be intended.only one-tenth of that area (W. Cordero, pers. Whether intended or not, the structural impactscomm.). of logging alter the relative proportions of

lifeforms and biogeochemical stocks, as well asAlthough difficult to detect on satellite images, nutrient and hydrologic cycling, productivitybut see Souza and Barreto (in press) for recent and energy flows.



Structure: Logging may affect the structural lowest logging intensities, to substantiallyattribute of the ecosystem component of greater amounts where heavy logging isbiodiversity by changing the biophysical followed by poison girdling of non-commercialproperties of soils, spatial heterogeneity of trees in the residual stand. Necromass,forest stands, and biomass. The extent and types including coarse woody debris, increasesof ecosystem damage to these structural immediately after logging but may thenattributes depend on logging intensity, yarding decrease to levels below pre-logging conditionssystem, and the care with which the operations due to increased temperatures near the groundare conducted. Soil compaction, for example, is and associated increases in decomposition rates.a major problem during ground-based yarding Wildfires promoted by logging roadoperations especially where skid trails are construction and canopy opening, as well asunplanned and yarding continues during wet controlled bums carried out for silviculturalweather. Where compaction is severe, soil purposes, can have obvious effects on biomasspermeability and bulk density often require and necromass stocks in tropical forests.many decades to recover. Exposure of mineralsoil after litter layers and root mats are bladed Maintenance of healthy communities, speciesoff by bulldozers is also a concern. Mineral soil populations, and gene pools is predicated upondisruption during bridge building, road protection of hydrological functions, nutrientconstruction and maintenance, and skidding cycles, and other ecosystem properties.operations also represent forest management Fortunately, methods for mitigating theactivities that affect ecosystem structure and ecosystem-level impacts of logging on tropicalthereby have biodiversity impacts. forests are well known. Switching from ground-

based to skyline yarding techniques, forLogging induced soil compaction negatively example, greatly reduces damage to residualaffects hydrology, which in turn alters the stands, soils, and streams but allows harvest oncharacteristics of watercourses. For example, steep slopes. The opposite trend in tech-water infiltration rates into soil, surface flow nological change also can have environmentalrates and volumes, and stream channel benefits; log yarding with draft animals or bycharacteristics are all adversely affected by manual means generally results in substantiallyuncontrolled logging. Deposition of large less logging damage than yarding withvolumes of unconsolidated sediments into bulldozers (Cordero 1995). To enjoy thesestreams during road construction and due to potential benefits, the expertise of experiencedincreased erosion from exposed mineral soils on forest engineers should be more often calledlog extraction routes can also greatly modify upon where logging does have to occur.stream characteristics such as pool-riffle-runratios. The impacts of such changes on aquatic Composition: One important way that loggingorganisms have been little studied in the tropics. affects the ecosystem-level compositional

attribute of biodiversity is by changingAnother impact of logging on ecosystem-level biogeochemical stocks. For example, soilstructure is reduction in biomass and alteration compaction reduces water holding capacity,of necromass. Losses of biomass due to forest which in turn leads to increased surface runoff.management activities include the amounts in Limited storage capacity in natural streams isthe removed timber, damage to trees in the further reduced by sedimentation, which meansresidual stand that result in mortality, and any that flow regimes can be greatly modified bysilvicultural treatments that result in tree death. logging, especially during the first years afterBiomass losses range from 5-10 Mg/ha at the logging is completed. Various RIL techniques,



such as installation of cross drains on skid trails, release. The deleterious impacts of logging oncan greatly diminish these impacts. forest carbon balance can be greatly diminished

by application of RIL techniques (Pinard andWhere large volumes of timber are harvested Putz 1996). Substantial biodiversity benefits areand post-logging forest recovery is retarded by also likely to result from RIL, but this and othersoil damage, fire, or weed infestations, standing co-benefits have not been well studied. Otherstocks of nutrients in biomass are greatly silvicultural treatments such as firereduced. Storage of nutrients released from management, weed control, thinning, andbiomass in necromass and soil organic matter is enrichment planting have various impacts ongenerally brief in lowland tropical forests due to both greenhouse gas emissions and biodiversityaccelerated rates of decomposition and low that should be investigated.

cation-exchange capacities in the soil. Theresults can be substantial leaching and, if theforest is burned, volatilization of nitrogen and Logging, especially if followed by silviculturalsulfur. treatments such as liberation of future crop trees

from competition, can substantially change theFunction: Logging affects the functional physiognomy, composition, and trophicattribute of ecosystem-level biodiversity by structure of forest stands. To a large extent,adversely affecting hydrological and these modifications represent the goal of forestbiogeochemical fluxes as well as productivity. "refinement" treatments applied to increaseReduced plant productivity results in part from volume increments and relative densities ofimpeded root growth, a consequence of logging- commercial timber species. This "standinduced soil compaction. Because most of the domestication" by nature reduces speciesavailable nutrients are usually found near the richness; rare, threatened and endangeredtop of the soil profile, blading of the soil surface species may become locally extinct especially ifalso diminishes nutrient availability in local they have no perceived commercial value.areas and otherwise interferes with nutrient These changes in composition and structurecycling. In more extensive portions of logging affect numerous community-level ecologicalareas where RIL guidelines are not followed, processes including colonization, predation and

nutrient cycling and hydrological functions are mortality rates, pollination, seed dispersal, andgreatly modified by reduced canopy timing and abundance of flower and fruit

interception of rain and mist, decreased uptake production.

of water and nutrients by the diminished Structure: The most obvious logging-inducedbiomass, and increased occurrence of surface impact on the structural attribute oferosion and landslides especially associated community-level biodiversity is the change inwith improperly located and poorly constructed proportions of successional stages in forestroads and skid trails. stands. Depending on harvesting intensities,

planning of roads and skid trails, and trainingChanges in carbon storage and flux associated and supervision of workers, logging can resultdirectly and indirectly with logging and other in large changes in the proportion of forest insilvicultural activities influence whether forests mature, recovering, and early successionalare net sources or sinks of "greenhouse" gases. stages. In some severely disturbed areas,For example, substantial logging-induced succession might be "arrested" by post-loggingtransfers of living trees to coarse woody debris proliferation of vines, bamboo, and other non-can have substantial effects on understory arboreal growth forms. Silvicultural treatmentsstructure and dynamics leading to more carbon such as thinning and vine-cutting can increase



the rate of succession and increase the microclimates that result from exploitation,proportion of stand growth concentrated in silvicultural treatment, and by hunting (see Box 5).

commercial species, but not without affecting Species impacts (see Appendices V and VI)biodiversity in more than the intended ways.

The species component of biodiversity hasComposition: For the community component of received the most attention from researchersbiodiversity, logging affects composition by concerned about the impacts of logging andchanging (often purposefully) the relative other silvicultural treatments in tropical forests.abundance of species and guilds inhabiting The most obvious species-level impact offorest stands. Relative abundances of tree logging is on the abundance and age/sizespecies with light demanding vs. shade tolerant distribution of harvested and damaged trees.regeneration, wind vs. animal dispersed seeds, Depending on the intensity of logging and thevertebrate vs. invertebrate pollinated flowers, care with which it is carried out, theand thick vs. thin bark, for example, are all reproduction, growth, and survival of a greatsubject to change in logged and otherwise number of species can be adversely affected. Insilviculturally treated forests. Likewise, reviewing this literature, it is important to notesieviculturatiyntreatedfforest. uikewofanise, s that the taxa studied were not selected atrersntto odifrnguilsonml random. Instead, in many cases, the species

(such as understory insectivores and arboreal chosenswer d, to be csensitie to,candfolivores) is influenced by forestry activities,. thus goo d i a of fensitr impacsDepending on a great number of factors relatedto the intensities, spatial scales, and modes of Structure: The most immediate and directforest intervention as well as characteristics of impacts of logging on the structural attribute ofthe focal taxa, effects of forestry activities can be the species component of biodiversity are

negative, positive, or neutral. For example, in suffered by the harvested tree species. Theireight studies that considered the impacts of populations are often left greatly depleted,logging on frugivorous birds, two reported especially in the larger size classes ofpositive impacts at the guild level, three reproductive individuals when management isreported negative impacts, and three reported based solely on minimum diameter fellingno change at all (Appendix IV). rules. Because of the spatial clustering

characteristic of many commercial timber trees,

Function: The functional attribute of the richest patches of forest are generally thecommunity-level biodiversity includes most severely disturbed, unless loggingnumerous key ecological processes (such as guidelines specify minimum spacing betweenpollination, herbivory, seed dispersal and harvested trees.

predation) all of which are affected by logging Changes in forest structure are suffered most byespecially under the most intensive specialist species of the forest interior. Aftermanagement interventions. Many of the effects logging, many formerly shaded microenviron-on these processes are a direct consequence of ments in the forest interior become drier,altered resource abundance (for example fruit brighter, warmer, and more easily exploited byfor frugivores or young leaves for folivores), some predators. For example, severe canopywhich in turn result from the logging-induced opening adversely affects litter invertebrateschanges in community structure and and their predators. For species that arecomposition. In addition to being influenced by generalists in their diets and wide-ranging inresource-base changes, these ecological their habitat use, such as many frugivorousprocesses are also affected by changes in forest canopy birds, the direct impacts of logging vary



Box 5Hunting in logged tropical forests

The escalating scale of wildlife harvest in logged areas is an insidious problem that may undermine thebiodiversity conservation potential of forests managed for wood production (Robinson and others 1999, Fimbeland others in press). Logging operations multiply the harvest of wildlife from tropical forests primarily byincreasing access to previously remote areas. These same access roads serve as conduits for commerciallytraded meat and other wildlife products. Although the magnitude of the impacts of subsistence hunting oftropical forest animals (for food, feathers, and skins for example) by indigenous people are non-trivial (Robinsonand Redford 1991, Redford 1992, Robinson and Bodmer 1999, Peres 2000), the impacts of commercial huntingare several orders of magnitude greater. Of particular concern is the tendency for hunters to target almost anyspecies larger than 1 kg, including many species that are vulnerable to extinction due to their long life spansand low rates of population recovery (Bodmer and others 1997).

Hunting pressures increases in logging areas partially because of the number of people involved in loggingoperations as well as by the increased access provided by logging roads. In formerly isolated forest areas,loggers themselves hunt (Ruiz and others in press) or provide ready markets for meat and other wildlifeproducts (Wilkie and others 1992, Bennett and Gumal in press). Local communities quickly shift toward com-mercial hunting to supply markets to which logging roads provide access. This shift initiates a positive feed-back cycle wherein money gained from wildlife products buys better weapons with which to hunt, which intum increases the harvest. Such escalations are unsustainable, however, and some species become locally ex-tinct.

Loss of wildlife threatens the sustainability of tropical to the extent that the animals targeted by hunters playkey roles in ecological processes including seed dispersal, seed predation, and herbivory (Redford 1992, Jansenand Zuidema in press). Even when animal species are not extirpated, their numbers may be reduced suffi-ciently such that they are rendered ecologically extinct. The loss of wildlife may have cascading effects on thestructure and composition of the tropical tree community with deleterious consequences for recruitment ofcommercial timber species. Such dire predictions are most likely to be borne out in areas such as the Guyanaswhere a large proportion of canopy trees are dispersed by large animals (Hammond and others 1996). Finally,as human populations expand and forest landscapes become more fragmented, the potential for wildlife to re-colonize defaunated areas will likely diminish.

While the deleterious consequences for wildlife of logging and other silvicultural treatments (such as vinecutting) deserve further investigation and mitigation, it should be recognized that the indirect impacts of log-ging resulting from increased access often far outweigh the initial damage done by even the worst predatorylogging.

from being somewhat negative, to neutral, to Species impacts of logging and stand refinementpositive. For the understory species that are treatments are of particular concern in smalladversely affected by logging, the effects may forest management units. Private landownerspersist for decades (Wong 1985, but see Lee and with less than 100 hectares to manage, forothers 1998). It is worth reiterating that the example, may be unwilling to set aside 10imnpacts of hunting on populations of large and percent of their forest for species preservation. Ifslow-reproducing animals generally overwhelm their forests are surrounded by similarly

managed or deforested areas, then blanketany potential benefits that they might have apation o refiement treatmet

application of stand refinement treatments orenjoyed after the canopy was opened by logging heavy logging can take a heavy toll on(Bennet and Dahaban 1995, see Box 5). commercial and non-commercial species alike.

Population sizes and structures of most speciesare also drastically modified by the fires that so Composition: Logging affects the compositionoften accompany uncontrolled logging. attribute of species-level biodiversity by



changing the abundance and distribution of across or even within taxa. Our review of thespecies. Unless logging is accompanied by other literature on primates, for example, revealedsilvicultural treatments designed to foster their few cases of consistent responses of species toreproduction and growth, the abundance and logging (Appendix VI). This variation can bepopulation structure of the harvested tree attributed to differences in logging intensities asspecies are greatly modified by logging (see Box well as to differences in the duration of post-6). Logging impacts on tree populations logging population monitoring. Silviculturalcontinue for many years after logging is treatments other than logging, especially vinecompleted because damaged trees suffer high cutting and crown liberation of future cropmortality rates, proliferation of weeds (such as trees, might have more consistent deleteriousvines) interferes with tree reproduction and impacts on canopy animals, but such impactssurvival, and population size reduction and have been little studied.fragmentation can decrease pollination levels andchange patterns and intensities of seed dispersal Small fragments of untouched forest thatand predation. Species composition of animals also remain within even heavily logged forests servechanges in response to the direct impacts of logging as important refugia for plants and animals.(such as canopy opening) and the associated Wildlife densities in these unlogged fragmentsindirect impacts as well (for example increased fire can be very high during and shortly afterfrequency and intensity, hunting, and forest harvesting, but then diminish as animalsconversion). recolonize the surrounding matrix. Many

1munplanned" reserves are on steep or otherwiseChanges in species composition in response to adverse sites, which certainly influences theirforestry operations are by no means consistent function as refugia. Implementation of

Box 6Lesser-known species-Marketing challenges, silvicultural

impediments, or desirable diversity?

Sustaining volumetric yields of timber is made challenging in tropical forests where many trees have littlemarket value (Plumptre 1996). Particularly where just a few species of light-demanding trees have readymarkets, species that are commercially lesser known or that have less desirable timber properties often renderregeneration-enhancing treatments prohibitively expensive (Fredericksen 1998, Pinard and others 1999). Wheremarkets for formerly lesser-known species have developed and they can therefore be harvested profitably,forest managers can financially justify creating the large canopy openings required for regeneration of themost valuable light-demanding timber species.

The same lesser known species that interfere with timber stand management treatments and present chal-lenges for wood technologists and marketing firms represent an important component of forest diversity. Oneindication of their importance is that whereas tree species with wind dispersed seeds (such as Dipterocarpaceaeand Meliaceae) dominate the international timber trade (ITTO 1996), a high proportion of species producingless well known timbers produce fleshy fruit and animal dispersed seeds (Jansen and Zuidema in press).

Silvicultural treatments applied to promote regeneration and growth of commercially desirable species mightbe made more feasible by increased market demand for what are currently lesser known timbers. While pro-moting sustained yield of the species being harvested, these silvicultural treatments intentionally result in atleast locally substantial modification of pre-intervention stand structure and composition. Compromises be-tween sustained yield and the more all-encompassing goal of sustainable forest management need to be in-formed by research on the direct and indirect impacts of increased timber harvesting (Fredericksen and others1999).



helicopter yarding, and to a lesser extent other management units in which population sizes ofaerial yarding techniques, may place many of all species are correspondingly small. Allelicthese unlogged patches in jeopardy. frequencies of commercial species change after

removal of a large proportion of healthyFunction: Demographic processes (such as reproductive adults. For species with highsurvivorship, fertility, and recruitment) and densities of advanced regeneration, geneticgrowth rates are two key functional attributes of structure of their populations are unlikely tothe species component of biodiversity that change dramatically after selective harvesting,logging affects. Populations of many organisms unless collateral damage is severe. Timber standare susceptible to large fluctuations after improvement treatments also may affect thelogging due to both the direct impacts on forest genetic structure of species targeted for removalconditions (for example microclimate and (such as woody vines) as wetr as theirfragmentation) and the indirect impacts of (uha od ie)a ela hifragmentingfio and forest condirectsim s Te associates, but these impacts have apparentlyhunting, fire, and forest conversion. The not been studied. Given the high proportion ofproliferation of disturbance-adapted taxa in vines and other plants that resprout afterlogged-over forests, some species of which are cutting (=coppice), large impacts on geneticnot native or were not previously common in cure are lkely.the area, can have large but as yet little studied structure are unlikely

imnpacts on the resident flora and fauna. Composition: The fact that most species are rare

Genetic impacts (see Appendix VII) in tropical forests implies that allelic diversitywill decrease with increasingly intensive

The genetic component of biodiversity is likely management interventions. Unregulatedto be the most sensitive of all components to harvesting of all merchantable individuals oflogging because of reductions in effective commercial species, for example, has immediatepopulation size and interruptions in gene flow. impacts on allelic frequencies that continue toAt present, however, little is known about the change due to decreased effective populationgenetic structure of any tropical organisms, sizes. Deleterious recessive genes may becomeeven commercially valuable timber trees (Ledig more apparent due to dysgenic selection and1992). Furthermore, the techniques required for heterozygosity may decline due to theassessing the genetic structure of populations "bottyeneck" effect in the small, isolatedare sophisticated and expensive. Except in a few potions that inut smarvestedcases, concerns about dysgenic selection, genetic populations that result from harvesting, forestdrift, and other genetic problems are based on fragmentation, and other direct and indirectcontroversial theory that is rapidly developing impacts of forestry activities (Styles and Khoslaas evidence accumulates. 1976, Murawski and others 1994a and b, but see

Newton and others 1996).

Structure: Logging affects the structuralattribute of the genetic component of Function: Logging may affect the functionalbiodiversity by reducing effective population attribute of the genetic component ofsizes and heterozygosity. Effective population biodiversity by interrupting gene flow, which insizes of both commercial and non-commercial turn influences outbreeding rates. Decreasedspecies are reduced by harvesting, other effective population sizes coupled with losses ofsilvicultural treatments, forest fragmentation, pollinators and seed dispersal agents can resultweed proliferation, and wildfires. There are also in reduced gene flow and inbreeding depressiongood reasons to be concerned about the effects in populations of both commercial and non-of logging and stand improvement treatments commercial species. Especially vulnerable areon dioecious species and in small forest populations represented by scattered mature



individuals and very few juveniles (for example obligate outcrossers, only very severemany "long-lived pioneers" such as the reductions in effective population size are likelymahoganies). Given the high proportion of to have much effect on gene flow (Ghazoul andtropical tree species that are dioecious or others 1998).


Overview of Biodiversity Con-servation in Relation to Logging

5 and other Silvicultural Treatments

Synthesis The impact of these silvicultural approaches on

A way of graphically displaying the impacts of each biodiversity component using threelogging on tropical for-ests (Figure 4) based categories were assessed. First, each

upon the various components and attributes of biodiversity component was scored as 'mostlybiodiversity as described above was developed. conserved" for cases in which their attributesAlong the vertical axis of our framework the are expected to usually stay within their naturalfive components of biodiversity were arrayed in range of variation. Second, biodiversitythe order of increasing susceptibility to logging components were scored as "affected" for casesimpacts (landscape, ecosystem, community, in which their attributes are expected topopulation/species, and genetic). The frequently fall outside their natural range ofhorizontal axis arrays a variety of approaches to variation. Finally, biodiversity components weresilviculture in order of increasing intensity. scored as "mostly lost" for cases in which their

Figure 4 Expected effects of a range of forest uses on the components of biodiversity

___- - .Legend:NTFP = Non-timber forest prod-

. ~~~~~~~~~~~~~~~uctsGenetic _

fA > MQSTLYRIL = Reduced-impact loggingc ~~~~~MOSTILY

3} .1% Reserves = Protected areas5 Species -oa LOST within logged units0

Refinement = SilviculturalE treatments such as liberation of

future crop trees from competi-6 Community AFFECTED tion, which can substantiallychange the physiognomy, com-

._% .position, and trophic structureL \ . of forest stands which are ap-> \csse plied to increase volume incre-

.2 Ecosystem \ ' ments and relative densities ofn0 MOSTLY \ commercial timber species0m CONSERVED Enrichment planting = Increas-

Landscape ing the stocking of commercialspecies by planting seedlings (orseeds) in logging gaps or along

A ~ ~ Yx x x cleared lines

t~ -900 CL = Conventional logging



attributes are expected to almost always fall use capability, biodiversity value, or theoutside their natural range of variation. capabilities and desires of local stakeholders. At

least two other dimensions of this multi-The scoring process used for Figure 4 was dimensional topic are captured in Figure 5, onadmittedly subjective; the scores were based on which it is indicated that every forest activitya reading of the literature and the authors' can be carried out over a range of intensities.experience. It is fully recognized that particular Correspondingly, each forest-use activitysituations might warrant different scores, and it generates timber volumes and financial profitsis emphasized that the purpose is to illustrate that also range widely (Figure 6). Recognizingwhat is believed to be a useful analytical that forest use practices vary over time with, forprocess rather than to obtain perfectly accurate example, market fluctuations and politicalscores. It is also emphasized that this change, and that biodiversity impacts are aframework serves to suggest hypotheses that function of a multitude of interacting factorsseem to be important research topics for operating at different temporal and spatialconservation biologists from a number of scales, it is hoped that Figures 4-6 present andifferent disciplines. accurate "snapshot" of the relationship between

biodiversity conservation and forestThe responses summarized on Figure 4 actually management.represent a multitude of impacts from adiversity of silvicultural approaches applied The impacts summarized in Figure 4 and thewith varying degrees of concern for biodiversity ranks and ranges of impacts and profits onover a large range of scales. Additionally, Figure Figure 5 are based on a combination of literature4 addresses neither the issue of profitability of reviews and the authors' subjective estimations.different forest uses nor issues related to land- For example, under the range of stocking levels,

Figure 5 Generalized biodiversity impacts plotted against expected short-term financial returns to forestowners or concessionaires (NTFPs = non-timber forest products)

Severe

(A et nv/e tona v oggin Y 1g (CL)/

E u Reced /'hi~~~~~~~~~~~~~~~i

.t

E

.0

Modest P areas

Small GreatFinancial Profitability


Overview of Biodiversity Conservation in Relation to Logging and other Silvicultural Treatments

Figure 6 Generalized biodiversity impacts resulting from different approaches to forest management fortimber. (CL = conventional logging, RIL = reduced-impact logging, refinement = any of a variety of silviculturaltreatments applied to increase rates of timber volume increment; and, reserves = protected areas within logged units)

Severe

E mn

4-.

sia 1

Modest

0 1 2 3 4 5 6Commercial Timber Production (m3/ha/yr)

terrain, and accessibility that logging is carried 1) Tropical forests are often assumed to haveout, reduced-impact and conventional logging developed their current structure,overlap in both impacts and profitability. composition, and functional propertiesNevertheless, particularly where logging is under a disturbance regime characterizedcarried out on steep slopes or under otherwise by small, localized, and naturaladverse conditions, application of most RIL perturbations. The importance ofguidelines results in immediate profits that are unrecorded widespread cataclysmiclower than those enjoyed by unconstrained anthropogenic and natural disturbances,conventional loggers. This observation helps especially those of past centuries, is seldomexplain why where regulations are non-existent recognized.or unenforced, conventional logging will likelybe used to log such areas. Correspondingly, 2) It is often assumed that regenerating treessome of the impacts of high intensity RIL harvested for timber is simply a matter ofoverlap those of low intensity conventional protecting advanced regeneration (forlogging, but the former generally has fewer example, seedlings, saplings, and poles) andadverse environmental impacts than the latter. providing small canopy openings in which

Troubling assumptions they can mature.

Three widely held and interlocking assumptions 3) Many people believe that devolution ofabout tropical forests complicate the issue of the authority over forests to indigenous groupscompatibility of forest management for timber and other rural communities will enhanceand biodiversity conservation: efforts towards sustainable management

Biodiversity Series - Impact Stuidies 29


and biodiversity conservation (Luckert are less secure. Some communities, such as the1999, Putz 2000). municipalities in Bolivia that have recently

received control over substantial forest areas,While these assumptions hold true in some may be indifferent about conservationtropical forests, many of the trees currently (Kaimowitz and others 1998). In other cases,being harvested actually regenerated under such as some communities in Nepal, devolutionconditions very different than those of today or of forest control has had substantialthose that will be created by harvesting alone. conservation benefits. Obviously the process ofThe most familiar example is provided by the devolution deserves scrutiny lest some turn outneotropical and African mahoganies (Meliaceae to be worse forest stewards than the loggingspp); these trees and many others like them are companies and national governmental agenciesthe heritage of slash-and-burn agriculture, they replace. Empirical evidence suggests thathurricanes, river meanders and/or catastrophic community behavior towards forests dependsfires of centuries past. The problem confronting on the forest richness or forest poorness of theirsilviculturalists managing for such light- particular situation, but many other factors aredemanding species is that promoting likely involved and deserve investigation.regeneration requires intensive standmanipulations which are expensive and have Conclusionsgreat impacts on the biodiversity present All consumptive use affects some component orimmediately prior to intervention (Lugo 1999). attribute of biodiversity, commonly affecting not

only the target resource but other factors as wellDespite accumulating evidence of substantial (Redford and Richter 1999). The population/and long-term pre-historical and more recent species component is most commonlyimpacts of humans on what were formerly understood to be affected by silviculturalconsidered "natural" ecosystems, it is important activities although effects, some of which areto recognize that the current rates, spatial scales, subtle or cumulative, are undoubtedly oftenand intensities of human-induced perturbations missed even in this comparatively well studiedoften far exceed the resilience of tropical forests. component. Of increasing importance is anForest recovery after disturbances such as understanding of how the community andmechanical clearing for pastures, for example, is ecosystem components have been (Runnelsknown to be extremely slow, especially if the 1995) and are being affected by logging andpastures are large or intensively used. Natural other silvicultural activities (Noss andregeneration in such areas can be accelerated Cooperrider 1994, Vitousek and others 1997,through application of silvicultural treatments, Fimbel and others, in press).but full recovery of diversity, from the genetic tothe landscape level, will require centuries, if it Recognizing that all significant interventions inoccurs at all. For example, although leaf natural forests have biodiversity impacts, allbiomass may recover quickly, in abandoned silvicultural decisions necessarily representagricultural clearings coarse woody debris compromises. Management for some goods oraccumulates at rates measured in centuries. services necessarily involves managementResearch progress on methods for afforestation against some others. What are "weeds" toand reforestation should not beguile us into timber stand managers are food sources, rarebelieving that, once destroyed, tropical forests species, carbon stores, or inter-crown pathwayscan be recreated. for other human and non-human stakeholders.

The biodiversity compromises involved inThe cause of social equity may be well served deciding whether to cut vines, retain seed trees,by devolution of management responsibility to or enhance seedling establishment by carryinglocal communities, but the biodiversity benefits out controlled burns should be informed by


Overview of Biodiversity Conservation in Relation to Logging and other Silvicultural Treatments

research. Unfortunately, very little is known and training, and the general slow rate at whichabout how tropical forests can be managed in most loggers are transforming themselves fromthe most biodiversity friendly manner. timber exploiters into forest managers.Researchers have instead focussed on Nevertheless, even the most harshly treatedenumerating the deleterious environmental forests maintain more biodiversity than treeimpacts of uncontrolled logging by untrained farms for pulpwood, oil palm plantations,and unsupervised crews. To inform decisions maize fields, or cattle pastures. Furthermore,about tropical forest management and to assure logging is often the environmentally leastthat biodiversity is protected to the maximum damaging of land uses that are also financiallyextent, more research is needed on how to viable (Pearce and others 1999). Given thesemaintain diversity in forests selected for conclusions, effective mechanisms for financinglogging. The large and rapidly growing body of forest protection and environmentally soundliterature on ecosystem management in both forest management are needed. It might alsonorth and south temperate forests (such as prove useful to evaluate critically the limits toKohm and Franklin 1997, Lindenmayer 1999) the assumption that well managed forests areshould provide inspiration and starting points less likely to be converted to other land usesfor tropical researchers intent on solving than forests that are logged without apparentbiodiversity related problems associated with concern for sustainability.forest management.

By focusing on the deleterious environmentalThe primary conclusions to derive from these impacts of tropical forest managementanalyses are that: activities, we often lose sight of the fact that

from a biodiversity maintenance perspective,D Different intensities and spatial patterns of natural forest management (that is, maintainingtimber harvesting, along with other forests as forests) is preferable to virtually allsilvicultural treatments, result in different land-use practices other than completeeffects on the different components of protection. The number of taxa with reportedlybiodiversity. inconsistent, neutral, or positive responses to

a Some components and attributes of logging is an indication that timber harvestingbiodiversity are more sensitive than others is not necessarily incompatible with protectionto forest management activities. of many components and attributes of

* Only extremely limited use will protect all biodiversity. This conclusion derives evencomponents (that is, large protected areas greater support from the fact that nearly all ofare essential for biodiversity conservation). the studies conducted to date on the

biodiversity impacts of logging were carried outThe capacity to mitigate the deleterious after unplanned logging by crews with noenvironmental impacts of logging and other training in reduced-impact logging techniquessilvicultural treatments should not be construed and no incentives to reduce their impacts. Asas constituting unilateral support for forest management practices improve undersustainable forest management as a market pressure or pressure from land-owners,conservation strategy. Such an endorsement is the deleterious environmental impacts ofunwarranted given widespread illegal logging logging and other silvicultural activities arein the tropics, widespread frontier logging and likely to be substantially reduced. Forests thatlogging of areas of high priority for biodiversity are carefully managed for timber will notprotection, the persistence of poor logging replace protected areas as storehouses ofpractices despite substantial efforts in research biodiversity, but they can be an integral



component of a conservation strategy that and effectively extend the conservation estate.encompasses a larger portion of the landscape Finally, it should be recognized that landscapethan is likely to be set aside for strict protection. management is consistent with the ecosystemIn other words, forests managed primarily for approach emphasized by the Convention ontimber, if managed properly, will supplement Biological Diversity (CBD).


6 Recommendations

1. Given that all substantial forest components of reduced-impact logging andinterventions affect some component or various other pre- and post-loggingattribute of biodiversity, the best way to silvicultural activities. Particular attentionassure biodiversity conservation is through should be paid to plant and animal speciesthe establishment and protection of large, with attributes that render them susceptible

properly located, and well managed to logging-induced extirpation (Martini andreserves and protected areas. others 1994, Pinard and others 1999).

Regional guidelines for certification need to2. In some parts of the world and some types be developed and regularly updated to

of forest, there should be no logging at all. reflect increasing knowledge about

biodiversity so as to assure that certification3. Existing legislation and regulations should efforts realize their conservation potential.

be enforced. Where they do not exist, or areweak they should be created or updated to 7. Measures to protect biodiversity should bereflect current conservation and sustainable included in all forest management plans.

resource management concerns. Particular attention should be paid to the

4. Within forests used for logging and other retention of nest and den trees as well assilvicultural activities, biodiversity species of great importance to biodiversity

conservation is enhanced by setting aside a conservation.

portion of the area for complete protection. 8. Wildfires need to be controlled. SuccessfulOptimally, these reserves should be large, fir e contro lled. Sude

shaped so as to minimize edge effects, cover fire control programs will need to includerepresentative areas of all the ecosystem public awareness building as well astypes present, and include features of implementation of existing technologies and

special concern for biodiversity methods. Research is needed for developingmaintenance such as water courses, rock cost-effective fire control measures withoutcrops, and salt licks. minimal biodiversity impacts.

5. Where logging is to be carried out, reduced- 9. While continuing to promote and developimpact logging guidelines (Dykstra and community-based wildlife managementHeinrich 1996) should be fully implemented prograrns, hunting by loggers and marketby well trained crews. hunting of slow reproducing species should

be prohibited. Enforcing existing laws will6. Researchers need to determine the financial in many cases confer substantial protection

and environmental costs and benefits of the to species threatened by over-hunting.



10. Training is needed for researchers who will 11. The biodiversity impacts of devolution,develop biodiversity-sensitive silvicultural plantation conversion, certification,methods as well as cost-effective methods 12. forest-based carbon offsets, and globalfor monitoring the environmental impacts trends in timber markets need to beof silviculture. Training is also needed for monitored.the field crews that are responsible forimplementing the recommended practices. 13. Linkages to the policy arena must bePerhaps the most critical shortage is of pursued. Ecosystems provide importantforestry/conservation "research services which typically are not internalizedpractitioners" who understand both the into the decision making process.broad scientific and the more specific Legislation and their regulations are antechnical aspects of tropical forest integral part of this process and should bemanagement. reviewed, updated and enforced.


Appendix I -Impacts of Logging (and othersilviculture treatments where noted)on the Landscape Componentof Biodiversity in Tropical Forests


Impacts of logging (and other silviculture treatments where noted) on the landscape component of biodiversity in tropical forests

LandscaPe attributesCategory Structure Composition FunctionVegetation, Soil & - Fragmentation / roads + greater access to > 50% forest area logged + species lost > Increased human colonization and fire &Water humans 4 increased deforestation (Kaimowitz & (Eastern Amazon: Nepstad et al. 1992) decreased migration of animals and gene flow

Argelsen 1998) in plants (if pollinators are restricted tofragments)

> Tree populations, biomass, and community > Ecological degradation of 1 °forest fragments > More than 50 yrs required for recovery of pre-composition affected more by edge effects from increased edge effects & new habitat logging structure (Uganda: Plumptre 1996)than by patch size (Amazonia: Gascon & matrix (Amazonia: Gascon & Lovejoy 1998) 200 yrs necessary for recovery of sppLovejoy 1998) composition following logging damage

(Malaysia, forest gap model: Kurpick et al.1997)

Increased spatial heterogeneity of habitats after > Increase in mixed forest (w/ valuable timber o Impoundments due to undersized or failed140 yrs of agroforestry, logging, & charcoal spp) & decrease of Cynometra forest patches culverts & bridge abutments kill trees and mayproduction followed by 50 yrs regeneration after arboricide treatment from 1951-90 influence fauna (F.E. Putz, pers. obs.)(Puerto Rico: Garcia-Montiel & Scatena 1994) (Uganda: Plumptre 1996) )> Increased likelihood of large scale accidental

> Maintenance & recovery of species fires due to canopy opening and roadscomposition in logged patches depends on (Amazonia: Cochrane & Schulze 1999) or fuellandscape context (Liu & Ashton 1999) accumulation from fire protection (Miombo

woodlands, Africa: Chidumayo 1988)

;O Complex mosaic of forest types & disturbance > Harvest gaps warmer than natural treefall gapsw/ 85% swamp forest & only 15% lowland (Amazonia: Vitt et al. 1998)forest escaping logging disturbance (W.Kalimantan, 8 yrs post-logging: Cannon et al.1994)

> Patches (I - 100 ha) of unlogged forests inheavily logged area (500- 1000 ha, 80-120m3 /ha) on steep slopes (>350) and in rockyareas (Sabah, Malaysia: Pinard & Putz 1996)

PrimatesNon-rodentmrommalsRodents & > Increased small mammal richness in forestMarsupials fragments b/c of increased edge and new

habitat matrix Gascon & Lovejoy 1998)

Birds

Herps > Neotropical frogs - see rodents above (Gascon& Lovejoy 1998)

Insects > Loss of species & genes of butterflycommunities b/c of conversion of 30% oflandscape to agriculture and forestry(Neotropics: Brown 1997)

Soil organisms

Appendix IIimpacts of Logging (and othersilviculture treatments where noted)on the Ecosystem Componentof Biodiversity in Tropical Forests


Impacts of logging (and other silviculture treatments where noted) on the ecosystem component of biodiversity in tropical forests

Ecosystem AttributesCategory Structure Composition FunctionVegetation, Soil & P Reduced biomass, basal area, and stem density > Thin barked species most susceptible to P Increased vulnerability to fire: ignition after 2Water (Uhl et al. 1991, Silva et al. 1995, Pinard & Putz logging (and fire) (Amazonia: Uhl & Kaufman weeks w/out rain in gaps vs. months in

1996, Webb 1998, Finegan & Camacho 1999) 1990; Pinard & Huffman 1997) understory (Amazonia: Cochrane & Schulze

> Reduction in large trees with hollows & holes 1999, Nepstad et al. 1999)important for wildlife (Australia: Gibbons &Lindenmayer 1996)

> 2/3 basal area, 3/4 number undamaged trees, > Higher richness (trees > 20 cm dbh) in logged P Decreased evapotranspiration & infiltration;I/5 no of emergents (>30 m), & 1/3 vs. unlogged, but when equal numbers of trees increased surface flow 4 nutrient lossescommercial volume of unlogged forest sampled richness was equal (W. Kalimantan, 8 (Brtower 1996, Poels 1987, Bruijnzeel 1992), but(Venezuela, 19 yrs post-harvest of 10 trees/ha: yrs post-logging: Cannon et al. 1998) nutrient bsses don't restrict productivity (ProctorKammesheidt 1998) > T related to 1992)

> Forest surface fires kill 40-95% of all trees w/ geography than whether a patch was logged; > Soil bulk density 6 yrs post-logging 60% greaterdbh > 10 cm (Amazon: Nepstad pers obs) richness higher in west of reserve and in logged than in undisturbed forest (Malaysia: Malmer &

patches (L.tanda, 60 yrs post 'sustainable logging': Grip 1990); skid trails estimated to require > 50P 36% biomass loss from Increased treePkp-e16)yst co'rhdaiccduty(aly:motlt (Aaoi, IAA fro frgmn Plumptre 1996) yrs to recover hydraulic corductvity (MaVsia:mortality (Amazonia, I00 m from fragment ~&Knrzna 96

edge, 10-17 yrs post-fragmentation: Laurance K& K 1996)etal. 1997)

> Increase in organic fuels (56 to 180 tons/ha) on > Reduced densities of timber spp & shift in > 100- 170 M tons of carbon/yr emitted fromforest floor (eastern Amazon, post-logging: Uhl dominance & age structure of canopy spp 1981-1996 (Asia: Houghton & Hackler 1999)&Kaufman 1990, Uhl & Vieira 1989) (Puerto Rico, post 140 yrs agroforestry, > 0.5% of total global carbon emissions (Brazilian

> Soil disturbance main factor limiting seedling logging, charcoal production & St yrs Amazon, 1996-97: Nepstad et al. 1999)regeneration & establishment (Kalimantan: regeneration: Garcia-Montiel & Scatena 1994)Gardingen et al. 1998)

> 5-40% of forest floor disturbed by roads, skid > Epiphytic & strangler Ficus spp suffer high rates > Post CL, stream suspended solids and turbiditytrails & tractor tracks (Cannon et al. 1994 of damage (Malaysia, post-logging: Lambert were 12x & 9x > control and levels persistedJohns et al. 1996, Pinard & Putz 1996, Sist et al. 1991) at least 5 yrs; RIL levels were 2x > control but1998a, Holmes et al. 1999) recovered after 2 yrs (Malaysia: Zulkifli &

Anhar 1994)

Vegetation, Soil & > Soil properties (i.e. BD, total porosity, sat hydr > Woody vines increased w/in 100 m of edges > Watershed sediment loads were 1 8x higher 5Water conductivity, & resistance to penetration) but didn't compensate for lost biomass from mos post & 3.6x higher I yr post-loggingVegetation required 12-52 yrs (skidtrails longest) to increased tree mortality Amazonia forest (Malaysia: Douglas et al. 1992)

recover (Malaysia: Kamaruzaman & fragments 10-17 yrs pcst fragmentation: Laurance > 200 yrs necessary for recovery of spp compKamaruzaman 1996) et al. 1997) following logging damages (Malaysia, forest gap

> Limiting harvest gaps to < 650 m2 (< 2 model: Kurpick et al. 1997)trees/gap) enhanced dipterocarp regen & > Runoff as % precipitation ranged from 58% -inhibited pioneer regen (Kalimantan: Gardingen 94% in plantations converted from forestet al. 1998) depending on method (Malaysia: Malmer 1992)

> Harvest gaps much larger than natural treefall > Road & skid trail impoundments may increasegaps & thus have less litter and shade & more methane emissions (F.E. Putz, pers. obs.)intense light (Amazonia: Vitt et al. 1998)

> Sediment loads have negative effects on> Tree basal area and commercial volumes dwsra qai ie(utai:Cmbl

recovered within 40 yrs post logging w/ MUS downstream aquatic life (Australia: Campbell &(Malaysia: Manokaran 1998) Doeg 1989)

Primates > Long distance seed dispersal and speciesmovements to/from different habitat patcheslikely impeded (no specific data)

Non-rodent > Species movements to/from different habitatmammals patches likely impeded (no specific data)Rodents & > Species movements to/from different habitatMarsupials patches likely impeded; seed predation rates

likely altered (no specific data)Bats > Species use of different habitat patches &

pollination & seed dispersal rates likely altered(no specific data)

Birds > Bird spp decline w/ increasing disturbance > Species use of different habitat patches likely(Lawton et al. 1998) altered; depending on spp., pollination,

predation, seed dispersal rates likely altered;(no specific data)

Herps

Community AttributesCategory Structure Composition Function

Insects > Arthropod diversity decreases when structural > Various ecosystem processes will be relativelycomplexity decreases (Holloway et al. 1992; unaffected (Vitousek 1990)Gardner et al. 1995) and/or b/c of changes inunderstory, litter, & soil microclimate (Blau1980, Kremen 1992, Spitzer et al. 1997,Camilo & Zou in press)

Soil organisms ) 25%-75% reduction in soil mycorrhizae > Termite richness lower in clear-cuts, but(Malaysia, post-logging: Alexander et al. 1992) higher in regenerating plots than I' forest

(Cameroon), but overall richness was similar in1 °, 3 yr and 17 yr secondary sites (Malaysia:Eggleton et al. 1995); changes in termite compmay be delayed after disturbance (Eggleton etal. 1997)

> Nematodes declined along disturbancegradient & were 40% lower in clearcut vs. 1'forest (Bloemers et al. 1997)

> Soil fungi increased from 17 spp in 7-yrregrowth to 27 in 16-yr regrowth; soilmicrobial popin's positively correlated w/ treedensity & basal area (India: Arunachalam et al.1997)

> Ectomycorrhizal diversity greater under open& regenerating canopies than in undisturbedforest (Kalimantan, 9 months post clear-cut orpartial logging, trees > 50 cm dbh: Ingleby etal. 1998)

> Termite populations increase afterconventional logging more than after RIL(Sabah, Malaysia, 80-120 m3/ha harvested: F.E.Putz, pers. obs.)

(MUS = Malayan Uniform System, a monocyclic approach to timber stand management)

Appendix IIIImpacts of Logging (and othersilviculture treatments where noted)on the Community Component ofBiodiversity in Tropical Forests


Impacts of logging (and other silviculture treatments where noted) on the community component of biodiversity in tropical forests

Community AttributesCategory Structure Composition FunctionVegetation > Increased proportion of open > Increased species richness (esp. light-demanding pioneer trees, shrubs i Decreased seed dispersal of 6 timber

canopy (Uhl &Vieira 1989, and lianas) > 10 yrs post-logging (Brazil: Verissimo et al. 1995, species in logged + hunted forest vs.Thiollay 1992, Cannon et al. Magnusson et al. 1999; Salick et al. 1995, Silva et al. 1995, Delgado et al. logged + protected forest (Costa Rica:1994, Mason 1996); up to 1997, Costa Rica: Webb 1998) Guariguata et al. in press)50% in gaps vs. 5-10% D Aggressive shade-intolerant spp dominate and competitively exclude > Fruit production of trees lower IO yrs(Hartshor 1978, Denslow other plants (Uganda: Struhsaker 1997) post-logging (Amazonia: Johns 1992)

> Greater density of > Multiple tree felling gaps most diverse, but dominated by pioneer tree > High degree of outcrossing and low densityunderstory vegetation 5-6 spp (Costa Rica: Webb 1998) of mature individuals (neotropics:yrs post harvest (Venezuela: Murawski 1995, Stacy et al. 1996)Mason 1996)

Remaining large trees o High dominance of few spp in heavily disturbed habitats (e.g., roads) > Seed production lower in several timberinadequate to sustain future (Costa Rica: Guariguata & Dupuy 1997) species (Uganda: Plumptre 1995)

harvests (Philippines, I 5 yrs Large-scale, long-term shift in spp composition after logging, augmented - Increased self-pollination attributed to lowpost-SLS: Tombec & by arboricide treatment of non-commercial spp (Uganda: Plumptre density of flowering individuals (MurawskiMendoza 1998) 1996) & Hamrick 1991, 1992) 4 less seed

> No change in overall richness & composition in logged vs. logged +thinned (Nicaragua; Salick et al. 1995)

Reduced tree density & > Increased irradiance 4 more early successional spp (Swaine 1996, > Wind-dispersed seeds fall in highercanopy closure, denser Mulkey et al. 1996, Whitmore 1998) especially vines & pioneers (Lowe numbers in gaps than in understorycover < 2 m above ground, & Walker 1977, Cannon et al. 1994) (Augspurger & Franson 1988, Loiselle et al.& equal ground cover Post-logging is different than o flli (Peters 1996) 4 higher colonization levels from(Indonesia, 5 yrs post- ostg seed for wind-dispersed spp.selective: Hill et al. 1995)

> Increased dominance of fast growing timber producing tree spp. aftersilvicultural refinement (Malaysia, MUS: Chua 1998)

Reduced leaf biomass but > Vine spp. richness and densities recover to pre-MUS logging and - Reduced dispersal of seeds carried byincreased leaf quality; treatment by 40 yrs (Malaysia: Gardette 1998) large-bodied, gap-shy frugivores (Gorchovreduced log distribution, Lich d ir d mo d d 40 d et al. 1993, Forget & Sabatier 1997) or that

regenerating stems, and siMcultural treatirent (Maoas div MUS: Wolseley et al0 1998) are scatterhoarded by caviomorph rodentsoverall trsieeutualteamnt(Mlysa,MSsWize e l.I(Forget & Milleron 199 I; Forget 1990,

(Madagascar, RIL, <10% > Palmspp.richnesslowerinloggedandMUStreatedforestthanin 1°forest 1993, 1994; Asquithet al. 1999) esp. ifforest: Ganzhorn 1995, (Malaysia Nur Supardi et al. 1998) hunting presentGanzhorn et al. 1990)

Vegetation > Fewerlargediametervines40 > Mortality rates 4x higher for spp w/ dbh >

yrs post MUS than in II forest 40 cm (S. India, 10-I5 yrs post- selective

(Malaysia: Gardette 1998) logging: Pelissier et al. 1998)

> Denning trees less available for > Tree mortality increased after

arboreal rodents & marsupols liberation/refinement treatments (Costa

after selective loggng Rica: Finegan & Camacho 1999)

(Auistralia: Laurance &(autra .A > Vine cutting promotes tree growth &Laurance 1996; In vchoa &Soriano in ) reduces logging damage but removes

important intercrown pathways for wildlife

> Repeated selective logging (reviewed in Putz 1991)

reduces abundance of largetrees and shifts compositionto earlier successional species(Australia: Home & Hickey1991

Primates > Increased infant mortality > Omnivore densities (1-25 trees harvested/ha, I-SO yrs post-logging, > Herbivory & frugivory - enhanced by low

for various spp. Africa, Asia, Amazon) - 8 spp decreased, 13 spp increased, 5 spp intensity (< 10% affected) logging

immediately after logging, showed no change; several spp showed opposite results in different disturbance (Madagascar: Ganzhorn 1995);

but some spp recovered 6- studies and/or different sites (reviewed in Plumptre & Grieser Johns in data lacking for higher intensities, but

12 yrs post logging press) presumed as variable as changes in spp

(Malaysia: Johns & Johns > Folivore/frugivore densities (as above) - 6 spp decreased, 5 spp densities

1995) increased, 3 spp showed no change; as above, several spp showed > Seed dispersal & predation - no specific

opposite responses in different studies/sites (Plumptre & Grieser Johns data; probably varies with animal densities

in press); hunting affects folivores more than logging itself (Africa: Oates > Vine cutting and liberation thinning

eta]. 1996) increased locomotory costs and

> Frugivore/folivore densities (as above) - 3 spp decreased, 2 increased, 4 susceptibility to predators for non-volant

spp showed no change; again, several spp responded differently in arboreal animals (reviewed in Putz et al.

different sites/studies (Uganda: Plumptre & Grieser Johns in press) 2000)

> Lemurs in dry forest (< 10% affected by logging) - increased sightings of > Predation of small primates by raptors may

all spp attributed to increased fruit & higher foliage quality on remaining increase in response to vine removal

trees (Madagascar: Ganzhorn 1995) (Suriname: S. Boinski, pers comm.)

> Monkeys in Zaire -4 spp preferred secondary forest: 3 others preferred

primary forest (Zaire: Thomas 199 1)

> Folivores - hunting has greater negative impact than logging (Africa:

Oates et al. 1996)

vp~ > Primate densities decreased in response to logging & MUS (Malaysia:

CA1 Laidlaw 1998)


Non-rodent > Browsers/grazers (e.g., Asian elephant, African buffalo, gaur, banteng, & > If no hunting, increased herbivory; ifmcmnmds sambar deer) increase (if no hunting) b/c of increased food quality hunting decreased herbivory

(Oates et al. 1990, Waterman & Kool 1994) & quantity Johns 1992); theonly sensitive spp in this guild was the giant forest hog (Hylochoerusmeinertzhageni) (reviewed in Davies et al. in press)

> Carnivores - mixed responses & few data; spp with restricted dietsmost sensitive (reviewed in Davies et al. in press)

> Species favored by hunters (e.g., duikers, pigs, peccaries), for specialtrade (e.g., elephants) and roadside feeders (e.g., Synceros caffer, Bosspp) decline (Davies et al. in press)

> Large, slow (moving & reproducing) species decline (hunting aconfounding factor) (Lahm 1994, Grieser johns 1997)

> Species dependent on fruits/seeds of timber species (e.g. Sus barbatus,Caldecott 1991) on closed canopy (e.g., Muntiocus atherodes, Heydon1994; Giao et al. 1998), or with limited dietary flexibility due toenergetic requirements (e.g., Tragulus spp. Heydon & Bulloh 1997)decline.

Rodents and > Arboreal marsupials - I sp declined & 4 spp unaffected after 8- 10 trees (50-55 > Increased seed predation rates (esp ifMarsupials m3) harvested/ha (Australia: Laurance & Laurance 1996) hunting) (e.g., Terborgh & Wright 1994)

> Small mammal populations most sensitive - according to models: (a) > Decreased predation on large seeds if largeSciuridae, Echimyidae & other canopy dependent frugivores/ granivores; seed predators extirpated (Putz et al.and (b) spp w/ low RA and restricted geog range (Ochoa et al. 1993, 1990)1995; Utrera 1996; Ochoa 1997; review in Ochoa & Soriano in press) ' Increase in Muridae may increase

colonization of small seeded tree spp.Small mammal populations least sensitive - according to models: Didephidae & (Hammond & Thomas in press)Muridae; semi-arboreal omnivores/predators increase (e.g., Didelphis spp. &Philander opossum; see above refs)

> Rodent spp richness increased soon after logging (Uganda, 9 trees/ha,62% canopy open: lsabirye-Basuta & Kasenene 1987, Muganga 1989),but decreased by 16 yrs post (Lwanga 1994)

> Rodent spp. richness increased, 2 dominant spp. decreased in abundancebut increased in body mass after logging (China: Wu et al. 1996)

Bats > Pioneer plant dispersers (e.g., Carollia. Artibeus & Sturnira) increase > Increased dispersal of pioneer plant spp;(Charles-Dominique 1986, Fleming 1988, Fenton et al. 1992, Kikkawa & decreased predationDwyer 1992, Brosset et al. 1996, Utrera 1996, review in Soriano &Ochoa in press)

> Phyllostominae (insectivores & vert predators) - decline (e.g., Artibeus > Reductions in insectivore populations couldobscurus, Vampyressa bidens, Phyllostomus elongatus, Tonatia result in increased herbivory rates withsauropila) or disappear (e.g., Vampyrum spectrum, Tonatia sylvicola, deleterious effects on forest resourceChrotopterus auritus, & Peropterix koppleri, Emballonuridae) (Fenton productivity (Soriano & Ochoa in press)et al. 1992, Brosset et al. 1996, Utrera 1996, review in Soriano & Ochoain press)

> Reduced guild complexity & kcal extinctions after logging (5.8 m3/ha, trees >40 cm dbh); effects exacerbated by enrichment strips (French Guiana: Brossetet al. 1996; similar findirngs in Venezuela: Ochoa in press; reviewed in Soriano& Ochoa in press)

> Open-forest, fast-flying spp w/ long, narrow wings do best b/c ofincreased gap area; dominated 6-yr post site w/ 6-7 trees/ha harvested(Australia: Crome & Richards 1988)

> Spp preferring medium to dense understory disappeared after brushingindicating high sensitivity to changes in forest structure (Miller in press)

Birds > Nectarivore & generalist frugivore/insectivores - nc or increase in most ) Herbivory & frugivory - reduced for fig-spp (ohns 1989a, 1992b; Lambert 1991; Thiollay 1992; Zakaria 1994, eating spp b/c of lower post-harvest1996; Mason 1996; reviews in Mason & Thiollay in press, Zakaria & density of Ficus spp (Lambert 1991)Francis in press, & Plumptre in press)

> Terrestrial & sallying insectivores (e.g., Tyrannidae) & other spp > Predation - expected to decrease b/c ofdepending on forest interior (e.g., those in mixed-spp flocks) decrease reduced insect prey abundance (b/c ofw/ logging (ohns 1989a, 1991 a, 1992a; Lambert et al. 1992; Thiollay hotter/drier conditions) (Mason 1995)1992; Zakaria 1994; Bennet & Dahaban 1995; Fanshawe 1995; Grieser

Johns 1996; Mason 1996; Owiunji & Plumptre 1998; reviews in Mason &Thiollay in press, Zakaria & Francis in press, & Plumptre in press)

Birds > Predators, foliage gleaners & large frugivores - inconsistent responses in > Seed dispersal - reduced b/c of avoidancedifferent sites/studies aohns 1991 a; Lambert et al. 1992; Thiollay 1992; of large openings in forest canopy (StoufferGrieserjohns 1996; Zakaria & Nordin 1998; reviews in Mason & & Bierregaard 1995a,b)Thiollay in press, Zakaria & Francis in press, & Plumptre in press)

> Understory spp. - nectarivorous increased; insectivorous decreased; > Colonization rates -expected to increaselatter trend worsened by enrichment planting (Venezuela: Mason 1996) when refuges provided w/in logged areas

-(ohns 1996)

_____________________________ Community AttributesCategory Structure Composition Function

> Interior understory spp declined by 37-98%; generalists & sppassociated w/ dense second growth, edges & large gaps increased;overall richness and abundance down 27-34% (French Guiana, 1- 17 yrspost, 38% undergrowth & 63% canopy loss: Thiollay 1997); (otherstudy: 3 trees/ha, 10 yrs post) - lower diversity b/c of more uniformhabitat (Thiollay 1992)

> Flycatchers, wren-warblers, trogons & woodpeckers declined;nectarivores & some frugivores increased (Malaysia, 8 yrs post-logging:Lambert et al. 1992)

9 Spp. richness lower than unlogged (Indonesia: Marsden 1998)> 1/3 spp expected to disappear (Liberia, logged fragment: Kofron &

Chapman 1995)

Herps > Heliothermic lizards - increased density of large lizards & altered comm > Competition & Predation - increases instructure (Amazonian treefall gaps: Vitt et al. 1998) generalist spp (Vitt et al. 1998)

> No change in reptile community comp or abundance (< 10% damage, 2- > Colonization - generalist spp (e.g, Hyla12 yrs post-logging: Bloxam et al. 1996) geographica) increase (Caldwell 1989)

> Lower amphibian diversity (Amazonia, high intensity logging or logging &fragmentation & roads: Pearman 1997, Vitt et al. 1998)

> Spp that live in leaf litter most severely affected especially after highintensity logging (e.g., monocyclic harvests); w/ less intense logging mostspp persist in short term, but invasion of 2° forest by large predatorylizards may extirpate small frogs & lizards; some frog spp increase afterlogging b/c of ponding in skid trail ruts or in stream impoundments

_._____________ (reviewed in Vitt & Caldwell in press)

Insects > Community comp of Araneae, Hymenoptera, Heteroptera, Homoptera, > Short generation times & high fecundityColeoptera, Orthoptera & Lepidoptera differed in 1° forest, logged allow rapid recovery of effectedforest & plantations (Uganda: Nummelin 1996) populations (temperate zone studies:

Huhta 1976, Heliovaara & Vaisanen 1984;Spp. restricted to understory, leaf litter & soil most vulnerable (reviewed tropics: Ghazoul & Hill in press)in Ghazoul & Hill in press)Geometrid moth diversity lowest in abandoned clearcut, highest in > Negative cascading effects on insect-forest logged w/ MUS (Malaysia: Intachat et al. 1997; Ghazoul & Hill in decomposition, nutrient cycling) are likely

Press) (Ghazoul & Hill in press)> Lower lepidopteran moth diversity after logging + conversion to

plantation; Coleopteran dung & carrion beetles less affected (Malaysia:Holloway et al. 1992; Ghazoul & Hill in press)

> Dung beetle spp. composition in RIL area resembles 10 forest more thanconventionally logged area (Malaysia: Davies in press)

> Butterflies, flying beetles, canopy beetles, canopy ants, leaf eater ants,termites and soil nematodes all declined along disturbance gradient(Lawton et al. 1998)

> Butterfly richness, abundance & evenness all decreased (Indonesia, 5 yrspost-logging: Hill et al. 1995)

> Cassidinae beetle richness greater in logged forest and plantations vs. 1°forest and logged forest community compposition more like plantations(Uganda: Nummelin & Borowiec 199 1)

> Opportunistic species increase after invasion of pioneer plants atexpense of closed forest spp (Holloway et al. 1992)

> Ant spp. richness similar in Io forest and MUS forest 40 yrs aftertreatment (Malaysia: Bolton 1998)


Soil organisms > Fruiting body (sporome) ) Mycorrhizal fungi spp. richness higher in MUS treated area than in 1°density of mycorrhizal fungi forest (Malaysia: Watling et al. 1998); wood-rotting organisms may behigher 40 yrs. After MUS better impact indicators for logging & other silvicultural treatments

treatment than in I' forest > Changes to soil properties directly influences soil fauna diversity (review(Malaysia: Watling et al. in Camilo & Zou in press)1998)

> Endogeic & anecic earthworm communities little affected by small scaleclearcuts & low frequency (>50 yr intervals) large scale (reviewed inCamilo & Zou in press).

Aquatic systems > Loss of instream & riparian zone diversity; decreased abundance of > Alterations in light & temperature regimes,fishes & benthic invertebrates intolerant of (a) high sedimentation, (b) stream sediment loads, turbidity, streamshifts in photosynthesis/respiration ratios, (c) invasive spp (review in chemistry, hydrology & fluvialPringle & Benstead in press) geomorphology may cause cascading

effects on aquatic food webs (Pringle &Benstead in press)

Appendix IV-Bird Responses (densitybased oninter-site comparisons) to Loggingin Tropical Forests, Organized byFeeding Guild


01 Bird responses (density' based on inter-site comparisons) to logging in tropical forests, organized by feeding guild

Ulu UluBudongo, Kibale, Tekam, Segama, Segama, Imatoca, Piste de St -Elie,

Site Uganda Uganda Malaysia Sabah Sabah Venezuela French GuianaLogging intensity 20-80 m3/ha 2! m3lha 18 trees/ha 79 m3lha 90 m3lha 5-8 m3lha 1O m3lha 10 m3/haRecovery (years since harvest) 25-50 25 6-7 3-4 9-10 1-6 1 10Hunting no no unknown no no no yes yes

GuildFrugivore + nc + - nc nc - -

Frugivore/insectivore (arboreal) nc + + + + + nc ncFrugivore/insectivore (terrestrial) nc + - - nc nc na naFrugivore/granivore nc nc na na na na na naGranivore nc + na na na + na naGranivore/insectivore nc + na na na na na naInsectivore (sallying) - - - nc ncInsectivore (terrestrial) nc ncInsectivore (arboreal foliage gleaner) nc nc - nc naInsectivore (understory foliage gleaner) nc + nc - nc

Insectivore (bark gleaning) nc - - nc

Insectivore/nectarivore nc nc nc + + +

Predator nc + nc + - na

Predator/frugivore na na - nc nc na

Source Owiunji and Dranzoa Johns 1989a Nordin and Lambert Mason 1996 Thiollay ThiollayPlumptre 1995 Zakaria et al. 1992 1992, 1997 1992,1997

1998 1997

Notes:

Density (calculated by same method within a study, but differed between studies). + = higher following logging, - = lower following logging, nc = no change,

na = information not available; P B 0.05. (Adapted from Mason and Thiollay, in press; Plumptre et al., in press; and Zakaria and Francis, in press).

Appendix VImpacts of Logging (and othersilviculture treatments where noted)on the Species Component ofBiodiversity in Tropical Forests


Impacts of logging (and other silviculture treatments where noted) of the species component of biodiversity in tropical forests

Species AttributesTaxa Structure Composition FunctionVegetation > Smaller size classes most affected > High grading large commercial trees > Reduced seed availability & reduced seed dispersal by rodents of

by felling, skidding, and road caused local extirpation of Caesalpinia large seeded commercial species after logging (Guyana: Forget &construction echincata, Ceiba pentandra, and Aniba Hammond in press, Hammond & Thomas in press)

> 62% seedling & 59% sapling duckei; Amazonia (Gentry & Vasquez > For dioecious species, seed crop decreases with increasingmortality (Malaysia: Borhan et al. 1988, Grieser Johns 1997) distance of males to females (Mack 1997)1987) > Harvesting figs promotes their ) Higher seedling mortality (esp. in very disturbed areas) in Sabah

S I 1I% of trees uprooted (Brazil: regeneration & may not have wildlife (Pinard et al. 1996)Uhl & Guimaraes 1989) impacts due to scarcity of well-formed (iade l 96trees (Bolivia; Fredericksen et al. 1999) > Lower seedling growth rates (Nussbaum et al. 1995)17 trees damaged for every tree > Populations of wild fruit trees are often ) Reduced density of adults (i.e. breeding individuals) 4 fewercut (E. Kalimantan: Abdulhadi et decimated by destructive harvesting (Peru: flowers per unit area (C. Peters, pers. comm.)al. 1981) Vazquez & Gentry 1989) > 1% increase in tree mortality 3-4 yr post-logging (Silva et al. 1995,

0 >50% of young trees killed (N. F1 & Camacho 1999)Queensland, Australia: Crome et Feganal. 1992) ) 4-fold increase in tree mortality 2 yrs post-logging (Thiollay 1992)

)0- - 60-70% of residual trees ) More resources available to residual trees b/c of reduction indamaged by logging (Fox 1968; canopy cover and stem density (Maitre 1991); but damaged treesNicholson 1979) may need to use resources to heal w/ net result of increase in

> Large and small trees killed with aborted fruits (Stephenson 1981)equal probability Johns 1988; > Potentially higher seed predation levels (Schupp 1990, C. Peters,Crome et al. 1992) pers. comm.)

> Species w/ type IIl population > Temporary increase in growth rates depending on extent ofstructure may be easily canopy opening (Wan Razali 1989)eliminated (C. Peters pers. > Mean dbh increment 2-3 x higher in logged vs. unlogged Jonkerscomm.) 1987)

> Spatially clumped pattern of > Lower growth rates after thinning + selective logging in (E.conspecifics shifts to dispersed or Malaysia: Primack et al. 1989)random patterns 4 reproductivebiology and logistics of future > Lower growth rate for Araucaria cunninghmamii (Australia: Enrightsilviculture 1978)

Primates > > See Appendix VI

Non-rodent > Civet densities in logged forest were onlymammals 20% of 1° (Malaysia, 2-12 yrs post

selective logging, no hunting: Heydon &Bulloh 1996); but increased when <33-50% forest impacted (Malaysia, 5- 10 yrspost logging: Johns 1983b)

> Tree shrew densitites greater 40 yrs postMUS treatment than 1 0 forest (Malaysia:Laidlaw 1998)

> Giant forest hog populations decline afterlogging (Davies et a]. in press)

> Elephant populations increase in responseto logging (Africa & Asia: Grieser Johns1997)

> Mousedeer (Tragulus) populations reducedafter logging (80- 100 m3/ha, Malaysia:Heydon & Bulloh 1997)

Rodents & > Squirrel & rat populations showed variableMarsupials & species-specific responses to MUS

(Malaysia, 40 yrs post-treatment: Laidlaw1998)

Bats > Vampire bat densities increase if cattleintroduced to logged areas aohns et al.1985, Wilkinson 1985, Johns 1988, 1992a,Fenton et al. 1992)

Birds > See Appendix IV

Herps

Insects

Soil organisms

Appendix VIPrimate Responses (by feeding guild)to Logging in Tropical Forests


Primate responses (by feeding guild) to logging in tropical forests; O=no change; - = decrease after logging; + = increase after logging

GUILD / SPECIES Ulu Segama Nanga Gaat Tekam Sg. Lalang Kemasul Pta da Kibabe Budongo Kalinzu Kirindy LopeCastanha

Logging Intensity (trees/ha) 20 10 18 > 20 >20 5.1 or 7.4 6-25 ? . I

Damage levels (% tree loss) 32-58 54 5 38 55 60 25 or 50% >50 ? IIYears since logging 6-12 0-4 0-12 20-30 20-30 11 12-28 1-50 4-20 1 -15

Omnivores

Cebus apella +Cebus albifrons +Lophocebus albigena 0/- 0Cercopithecus Ihoesti O_0Cercopithecus ascanius +1- + + ICercopithecus cephus 0Cercopithecus medius +Cercopithecus mitus _ 0/- + 0Cercopithecus pogonias 0Cercopithecus nictitans . 0Ga/ago s_p .

Gorilla gorila 0Macaca spp _Macaca SPP _Macaco fascicularis 0 + .MacOca nemestrina 0 0 + 0Mandrillus sphinx 0Microcebus spP +Pan trogtodytes 0/- 0 + +Perodicticus potto .Phaner furcifer _ +Pongo pygmaeus +Saguinus mystax +Saimiri sPP _ +

Folivores/frugivoresAlouatto seniculus _

Ateles paniscus 0Callicebus moloch +Callicebus torguatus __ __ +Procolobus badius 0/-Colobus guereza . + + 0Colobus satanus 0Presbytis hosei + .Presbytis melalophos + _Presbytis obscura +Presbytis rubicunda . .

Frugivores/folivores I I l_l

Hylobates tars +

Hylobates muelleri 0_ Lagothrix lagotricha

Pithecia albicans + _

References Johns Dahaban Johns Laidlaw 1994 Laidlaw 1994 Johns 1991 b Skorupa 1986, Plumptre & Howard Ganzhorn White 1992,

1989a,b 1996 1989a,b 1988; Weisenrseel Reynolds 1991; 1995; 1994et al. 1993; 1994 Hashimoto Ganzhorn et

Chapman et al. 1995 al. 1990

* Modified from Plumptre and Grieserjohns (in press)

u-

Appendix VIIImpacts of Logging (and othersilviculture treatments where noted)on the Genetic Component ofBiodiversity in Tropical Forests

Biodiversity Series - Impact Stutdies 61

Impacts of logging (and other silviculture treatments where noted) on the genetic component of biodiversity in tropical forests

Genetic AttributesTaxa Structure Composition FunctionVegetation P Genetic diversity decreased by ' Outcrossing rates unchanged in Shorea leprosula (Chan 198 1,

5.0-23.4% (logged I yr prior; Lee et al. 1996, Wickneswari et al. 1997) & Dryobalanopsregenerated stands showed no aromatica (Kitamura et al. 1994)

significant loss); effect on dioecious Outcrossing rates decreased in Shorea megistophylla (Murawskispecies perhaps underestimated et al. 1994a,b); density of mature individuals likely an important(Wickneswari et al. 1997) factor

> Reduced cross-pollination rates in Shorea siamensis after logging(Ghazoul et al. 1998) and reduced pollination success ofDipterocarpus obtusifolius after logging S. siamensis (Ghazoul1999)

P Outcrossing rates of Carapa spp. were lower after controlledexperiments in logged vs. unlogged forests in French Guiana(Doligez & Joly 1997) but were not significantly different inCarapa stands in Costa Rica (Hall et al. 1994) possibly becauseof very high stand densities in Costa Rica.

P Studies citing genetic erosion of Swietenia mahoganii fromlogging have not been substantiated in follow-up studies(reviewed in Lugo 1999)

PrimatesNon-rodent mammalsRodents & MarsupialsBatsBirdsHerpsInsectsSoil organisms _s_ _

Glossary'

Advanced regeneration: seedlings or saplings compound) interest rate; used to calculate thepresent in the understory prior to logging or "net present value"other silvicultural treatment

Edaphic: related to or caused by particularAerial logging: a timber yarding system using conditions in the soilsuspended cables, helicopters, or balloons to liftlogs Enrichment planting: increasing the density of

desirable species by interplanting, planting inAfforestation: establishment of forests in areas gaps, or planting along cleared linesthat did not historically support them (e.g., insavannas or drained marshes) Fragmentation: the process of breaking once

continuous expanses of an ecosystem typeBole: trunk or main stem of a tree (typically forest) into island-like patches in a

matrix of other land usesBuffer zone: vegetation maintained on theborders of roads, wetlands, or other ecologically Gap: generally refers to a hole in the canopysensitive areas to mitigate the impacts of created by the death of a canopy tree, but theremanagement activities are also understory gaps and belowground gaps

Bulk density: the weight per unit volume of a Girdle: to make an incision around a tree trunkmaterial (often soil) at least as deep as the cambium with the

intention of killing the tree; if combined withCarbon sequestration: carbon storage arboricide application then referred to as

"poison girdling"Coppice: sprouting of trees from stumps orroots Group selection: harvesting of trees in clusters

generally no wider than twice the height of theCutting cycle: the time (years) between stand mature trees to promote regeneration ofentries for timber extraction; there can be more moderately light-demanding species (athan one cutting cycle in a "rotation" "polycylic" system)

Dendrology: the study of trees including their Hauling: carrying logs by truck (lorrie) from theidentification forest to processing or exporting facilities

Discounting: adjusting a future value by Heartrot: decomposition of the centraldividing by a function of the (generally stemwood of living trees typically due to fungal



infection after mechanical or fire-related Reduced-impact logging: a set of techniquesdamage designed to avoid excessive damage to soil or to

the residual stand during and after timberHeterozygous: having two different alleles at harvesting; typical components include pre-the same locus on homologous chromosomes; planned skid trails, directional felling, andan index of genetic diversity engineering specifications for stream crossings

High-grading: removal of the best trees often Reforestation: the recovery of forests in areasleaving a residual stand dominated by trees of that were deforested; compare to "afforestation"poor form and non-commercial species;"creaming" Regeneration method: a timber harvesting

method that promotes development of a newHighlead yarding: a yarding system in which age class; the principal methods includelogs are skidded along the ground to a central clearcutting, seed tree, shelterwood, selection,point by a cable passing through a block at the and coppicingtop of a tower or spar tree (not to be confusedwith "skyline yarding") Riparian: a terrestrial area bordering a water body

Liana: woody vine Rotation: the period between establishment ofregeneration and final harvesting in even-aged

Liberation thinning: a silvicultural treatment in standswhich future crop trees are released fromcompetition typically by girdling near neighbors Shelterwood method: a stand regeneration(note: term used differently by many North method that occurs in two phases, a first phaseAmerican foresters) in which enough timber is harvested to promote

development of a new age class in partial shade,Logging intensity: can refer to either the timber and a final felling of the remaining maturevolume or number of trees harvested per unit timber after regeneration is establishedarea

Silviculture: the art and science of controllingNatural forest management: management of the establishment, growth, composition, andforests for timber, non-timber forest products, health of forests and woodlandsand environmental services by relyingprincipally on natural regeneration (compare to Skidding: yarding logs with a rubber-tired self-plantation forestry) propelled machine or bulldozer ("snigging" in

Australia)Neotropics: American tropics

Skyline yarding: a log yarding system in whichNet present value: the current value of some logs are partially or entirely suspended from afuture cost or benefit taut cable (not to be confused with "high-lead

yarding")Paleotropics: tropical areas in Africa, Asia,Australia, and the Pacific Islands Stand: a contiguous group of trees with a more-

or-less similar history of disturbance, speciesPlantation: a stand of trees established by composition, size-class distribution, andplanting; tree farm structure


Glossary

Succession: the gradual change in structure and Yarding: the process of extracting logs from thecomposition as an area recovers from stump to the roadside, river edge, or other sitedisturbance or on previously un-vegetated areas from which they are hauled

Thinning: a silvicultural treatment designed toreduce stand density Note

Tractor: can refer to a bulldozer (=powered 1. Based heavily on Helms (1998).vehicle with crawler tracks) or a farm tractor


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