2009 report: how air quality affects vermont forests

8/3/2019 2009 Report: How air quality affects Vermont forests

1/44

1

Vermonts Changing Forests

Key Findings on theHealth of Forested Ecosystems from the

Vermont Monitoring Cooperative

O 2009


2/44

VMC S

Donnie Ager, Web & Data Assistant

Lawrence Forcier, Principal Investigator

Joanna Grossman, Web & Data Manager

Mim Pendleton, Monitoring Technician & Site Operator

Judy Rosovsky, Monitoring Assistant

Carl Waite, Program Coordinator

2009 VMC S C MAnne Archie, USDA Forest Service

Douglas Lantagne, University o Vermont

Ed OLeary, Vermont Agency o Natural Resources

Dennis May, USDA Forest Service

Steve Roy, USDA Forest Service

Robert Paquin, USDA Farm Service Agency

Charles Scott, USDA Forest Service

Steven Sinclair, Vermont Agency o Natural Resources

Mary Watzin, University o Vermont

2009VMC A C M

Barbara Burns, Vermont Agency o Natural Resources

Nancy Burt, USDA Forest ServiceBrian Keel, USDA Forest Service

Bill Keeton, University o Vermont

Jim Kellogg, Vermont Agency o Natural Resources

Rich Poirot, Vermont Agency o Natural Resources

Beverley Wemple, University o Vermont

Deane Wang, University o Vermont

Sandy Wilmot, Vermont Agency o Natural Resources


Providing the information needed to understand, manage, and protect Vermonts forested ecosystems

in a changing global environment.

The Vermont Monitoring Cooperative (VMC) was established in 1990. In 1996, a memorandum o understanding

was signed by the Vermont Agency o Natural Resources, the University o Vermont, and USDA Forest Service.

The partners agreed to work together to operate VMC to better coordinate and conduct long-term natural resource

monitoring and research within Mount Manseld State Forest, the Lye Brook Wilderness Area o the Green

Mountain National Forest, and other relevant areas in Vermont.

The Vermont Monitoring Cooperative works in partnership with the USDA Forest Service State & Private Forestry as

part o the Cooperative Lands Forest Health Management Program. The majority o VMC operations are handled by

sta aliated with the Rubenstein School o Environment and Natural Resources at the University o Vermont, the

Vermont Department o Forests, Parks & Recreation in the Vermont Agency o Natural Resources, and the USDA

Forest Service Green Mountain National Forest.

VMC C j:

James S. Andrews, Vermont Reptile and

Amphibian Atlas Project

Lesley-Ann Dupigny-Giroux, University o Vermont

Steve Faccio, Vermont Center or Ecostudies

Jennier Jenkins, University o Vermont

William Keeton, University o Vermont

Ron Kelley, Vermont Agency o Natural Resources

Jim Kellogg, Vermont Agency o Natural Resources

Trish Hanson, Vermont Agency o Natural Resources

Kent McFarland, Vermont Center or Ecostudies

Eric Miller, Ecosystems Research Group, Ltd.

Heather Pembrook, Vermont Agency o Natural Resources

Rich Poirot, Vermont Agency o Natural Resources

Chris Rimmer, VermontCenter or EcostudiesDonald Ross, University o Vermont

Jamie Shanley, U.S. Geological Survey

Tom Simmons, Vermont Agency o Natural Resources

Christopher Still, University o Caliornia, Santa Barbara

Thomas Villars, Natural Resources Conservation Service

Beverley Wemple, University o VermontSandy Wilmot,Vermont Agency o Natural Resources


3/44

V A N R

U V

U S F S

Vermonts Changing Forests

Key Findings on the

Health of Forested Ecosystems from the


October 2009


4/44


5/44

3

A B H V M C

A major Vermont Forest Health Task Force assembled by then-Governor MadeleineKunin determined that Vermont needed to continuously monitor orest health andimportant environmental variables. In 1990, there were very ew models on which to build astatewide monitoring and research program. That year, through the eorts o VermontSenator Patrick Leahy and his sta, the U.S. Congress appropriated $250,000 or the

establishment o VMC. Leaders o the three ounding organizationsthe Vermont Agency

o Natural Resources, the University o Vermont, and the U.S. Department o AgricultureForest Serviceagreed to jointly orm, nurture, and administer VMC as a long-term naturalresource monitoring program. VMC prided itsel on a collaborative approach toorganization and administration, in both its daily operations and its longer-term monitoringinitiatives. VMC encouraged and embraced involvement and guidance rom caring andknowledgeable individuals working outside o the immediate partner organizations. In1996, the three ounding partners signed a ormal memorandum o understanding in whichthey agreed to work together to operate VMC with the goal to better coordinate and

conduct long-term ecological monitoring and research within the Mt. Manseld StateForest, the Lye Brook Wilderness Area o the Green Mountain National Forest, and otherrelevant areas in Vermont. In the process o developing the memorandum, the broad andecient involvement o many Vermonters and other proessionals was recognized as an

important outcome o this phase o the Vermont Monitoring Cooperative, and an elementthat should be promoted as VMC continued to evolve.

VMCs mission is: To provide the inormation needed tounderstand, manage, and protect Vermonts orested ecosystems

within a changing global environment. VMC seeks to serveVermont through improved understanding o annual conditions,long-term trends, and interrelationships o the physical, chemical,and biological components o orested ecosystems by collectingand disseminating Vermont environmental data. VMC alsopromotes the ecient communication and coordination omulti-disciplinary environmental monitoring and researchactivities among ederal, state, university, and private entities

with common interests in the long-term health, management,and protection o Vermonts orests.

VMC has become an important database and inormationmanagement service or Vermonts study o orest ecosystemsand environmental quality. The VMC data library contains 300research and monitoring projects and datasets, collected overnearly two decades by dozens o cooperators on a wide array o environmental topics (seepage 38 or a sampling o VMC projects and datasets; a more complete listing can be oundat the VMC web site: www.uvm.edu/vmc). VMCs cooperators range rom undergraduateand graduate students doing research or class projects and theses to university, state,

ederal, and private-sector research and monitoring scientists. Through VMC, all results areassembled in a collaborative eort to advance knowledge and understanding o the

environment and Vermonts orests. VMC data and inormation resources are used bystudents, natural-resources managers, scientists, lay citizens, and policy makers. VMCaccomplishes its mission through a small proessional sta, many other committedproessionals and volunteers, contemporary data management systems, education andoutreach programs, and continuing eorts to support and help coordinate Vermontsenvironmental data interests. VMC continually upgrades its data services to provide the

best data quality and accessibility possible.

VMCs mission:To provide theinormation neededto understand,manage, and protectVermonts orestedecosystems withina changing globalenvironment.

VMC cooperators have

conducted research

on Vermont orests or

18 years, amassing a

wealth o long-term

data.


6/44

4

A Steering Committee, whose members represent the three ounding partnerorganizations, guides the planning, administration, and policy development or VMC. AnAdvisory Committee, with members rom Vermonts scientic research, monitoring, andresource-management communities, helps inorm decisions about operations, unding,and support needs or research and monitoring projects, and advises on direction or the

organization in general.Mount Manseld was the rst o two study sites selected by VMC or intensive orest

ecosystem monitoring and research (Figure 1). This site comprises over 5,500 acres o stateand university-owned land located between 1,300 and 4,300 eet in elevation. It includesthree watersheds, northern hardwoods and montane spruce-r orest types, as well as analpine ecosystem. VMC utilizeson-site laboratory acilities at theUniversity o Vermonts ProctorMaple Research Center (PMRC).

At PMRC, VMC operates eldcollection sites or the NationalAtmospheric Deposition Program(NADP)/National TrendsNetwork, NADP/AtmosphericIntegrated Research Monitoring

Network, NADP/MercuryDeposition Network, U.S.Department o Agriculture

UV-B Monitoring and ResearchProgram, and the Vermont AcidPrecipitation Monitoring Program.Other VMC acilities andinrastructure include a 66-ootwalkup canopy tower; thelongest continually operating wetatmospheric mercury monitoring

station that we are aware o in the

world; ve meteorologicalstations; three stream-gage stations; and a remotely accessed soil climate station. TheVermont Air Pollution Control Division also operates aco-located air quality monitoring station at PMRC.

The Lye Brook Wilderness Area, the second VMC intensive study site, provides asouthern Vermont complement to Mount Manseld. It encompasses 15,000 acres o GreenMountain National Forest land, ranges in elevation rom 900 to 2,900 eet, and supportsnorthern-hardwood, spruce-r, and paper-birch orests. The Lye Brook areas surace waters

identiy it as being sensitive to acid deposition. Lye Brook supports a remotely accessedatmospheric monitoring station (ozone, wet and dry deposition, and meteorology), airvisibility monitoring, and a soil climate station.

VMC data collected and archived during the past 18 years have made signicant

contributions toward our knowledge about climate change, land-use ragmentation, andthreats rom insects, diseases, invasive plants, and air pollution. VMC data have been usedin Vermont to determine the best time to spray or orest tent caterpillars in order to protecteconomically and ecologically important sugar maple trees, while minimizing the negativeeects on the endangered Indiana bat. Data collected by herpetologists tell us that while

numbers o the smooth greensnake may be declining in Vermont, the only viable populationo the North American racer may have already disappeared within the last two years. VMCresearchers ound that Bicknells thrush tend to avoid crossing open areas such as openski trails and that male thrushes may be more vulnerable to predation when crossing theseopen areas.

Mount Manseld

Lye Brook

Figure 1: The majorVMC study sites at

Mt. Manseld and

Lye Brook Wilderness

Area, indicated by

dots, are shown here

within the context o

the biophysical regions

o Vermont.

Source: Sandy Wilmot and

Beverley Wemple


7/44

5

VMC-supported projects have shown that high-elevation developments increase annualwater, sediment, and chloride yields over undeveloped watersheds. Also, we now know that,on average, sugar maple budbreak is three days earlier and lea-out ve days earlier this decadethan in the 1990s; the 2008 budbreak was 12 days earlier and lea-out was nine days earlierthan the baseline. A map o orest soil carbon assembled by VMC researchers which shows

areas o high or low carbon may suggest uture guidelines or managing soil carbon. In a 2007lawsuit led by the U.S. Environmental Protection Agency and eight northeastern statesagainst a large midwestern utility company, data rom PMRC in Underhill helped providecompelling evidence that the company was keeping outdated power plants in service to avoidthe costs o producing cleaner power; in an out-o-court settlement, the company agreed tospend $4.6 billion to retrot several old power plants. Because o the pioneering work doneby VMC cooperators, Vermont is a strong candidate or a role as a pilot site in an anticipatednational mercury biomonitoring network. The Underhill monitoring site known as VT99 wasrecently selected and unded by EPA as one o the initial sites in the new NADP/Mercury

Trends Network.The work o VMC has helped Vermonts leadership role on the national stage in certain

environmental issues. During the potentially uncertain times brought about by climate change,continuing threats rom air pollution, and changes in land use both locally and nationally, it ismore important than ever to support monitoring o environmental variables and conditionsand to eciently and eectively share scientically robust data among scientists, resource

managers, policy makers, and the public in an unselsh spirit o cooperation. Ecosystemhealth is an essential element to achieve sustainability. The need or useul indicators oorest ecosystem health recognized by Vermont and ederal leaders 20 years ago is even

more important in 2009.

8

7

6

5

4

3

2

1

0

1989

Hermit Thrush Decline

1990

1991

19

92

1993

19

94

1995

19

9619

97 1998

1999 20

00

2001

2002

2003

20

04

2005

2006

AnnualIndex

Annual Trend = -6.3% (SE 0.024)

P= 0.011

T S V S B: H T D

R

Figure 2: Populations o hermit thrush havedeclined by 6.3 percent annually at more than

two dozen VMC study sites.

Source: FBMP

esults rom the VMC-supported Vermont ForestBird Monitoring Program (FBMP) indicate thatVermonts state bird, the hermit thrush, declined by

an average o 6.3 percent annually between 1989 and 2006(Figure 2). FBMP monitors breeding birds at more than twodozen orested study sites throughout the state, includingsites at Mt. Manseld and Lye Brook. Several actors mayhave contributed to this long-term decline, including habitatalterations rom deer overbrowse, soil calcium depletion

due to acid rain, andhabitat loss, especially onthe birds southeastern

U.S. wintering grounds.

n Hermit Thrush

During thepotentiallyuncertain timesbrought aboutby climate change,continuing threats

rom air pollution,and changes inland use bothlocally andnationally, it ismore importantthan ever tosupport monitoringo environmental

variables andconditions.


8/44

6

Figure 3: More than 80 percent o Vermontsorests are privately owned.

Source: Adapted rom Wharton et al. 2003

T L O T

T

Distribution of Timberland Area by Ownership

Individuals:

63%

Federal: 6%

Other Public: 8%

Forest Industry: 6%

Farmers: 6%

Corporations: 11%

he history o the Vermont landscape is marked by the inuence o geologic orces that gave rise to the states

mountains over 400 million years ago and climatic orces that have produced dramatic changes in

environmental conditions. Roughly 11,000 years ago, glacial ice that had extended over the state or nearly two

million years began to retreat and trees began to appear on a landscape stripped bare o vegetation. These earliestorests were dominated by black spruce and paper birch. Animal communities became established in new habitats

made available in the emerging orests. As the climate warmed, tundra vegetation retreated to only the states

highest peaks, while spruce and r dominated the higher elevations and northern mountains. Lower elevations came

to be dominated by eastern white pine, maple, birch, hemlock, beech, oak, and hickory, creating todays mosaic o

the mixed northern hardwood orest. Today orests cover roughly 4.6 million acres or roughly 78 percent o the state

(Wharton et al. 2003).

The current predominance o young to mature orests is an artiact o 19 th-century clearing, subsequent

land abandonment, and secondary orest redevelopment on old-elds. With these changes have come shits in the

types o ecosystem services provided by orested landscapes. For example, young to mature northern hardwood

orests provide less desirable habitats or late-successional wildlie species, lower levels o biomass and associated

carbon storage, and less dramatic eects on aquatic habitat structure in orest streams (Keeton et al. 2007). On the

other hand, a young, maturing orest has higher growth rates, providing opportunities or sustained yield timber

production. In addition, open lands and young orests provide abundant habitats or early-successional species,

some o which are now declining due to orest redevelopment.

Compared to the primary (or never cleared) orest systems, the secondary orests that have recovered across

Vermonts landscape tend to have less complex canopies, lower densities o large trees (both live and dead), lower

volumes and densities o downed logs, smaller canopy gaps, and less horizontal variation in stand density (McGee

1999, Keeton et al. 2007). At larger scales, our land-use and orest-management history has converted landscapes

with complex patch mosaics, which are shaped by wind and other disturbances, to simpler congurations. Forest

patches are now less diverse in size and less complex in shape (Mladeno and Pastor 1993). The relative abundance

o dominant tree species has also shited as a result o land-use history (Cogbill et al. 2002). As we evaluate the

current conditions and trends in orest ecosystem health indicators, we need to keep in mind that land-use history

has prooundly shaped our current orested landscape.

Modern changes to the Vermont landscape accompany dramatic changes in the states population over the

last ew decades. The population boom in the United States ollowing the Second World War did not reach Vermont

until later, with a 14 percent population growth in the 1960s and a 15 percent growth in the 1970s, and rates slowing

to 10 percent or less in more recent decades. With this population growth, came a change in urbanized land,which has grown by roughly 20 percent since 1960. Nearly one-third o urbanized land has come rom conversion

o agricultural land and nearly two-thirds rom conversion o orest land. Although much o this population and

development pressure has been ocused in the Champlain Valley and more populous towns o the state,

a signicant eature o Vermonts recent growth has been a growth

in recreational development and second homes in Vermonts

resort towns. Demographic changes and pressures associated

with property taxation have led to changes in land ownership and

increased parcelization o orest land across the state. Today, more

than 80 percent o Vermonts orests are privately owned (Figure 3).

These changes in population, land ownership, and land use have

important implications or orest ecosystem health.

A 1999 EPA report estimates a loss o approximately 35

percent o our wetlands since European settlement, with morerecent annual losses o 200 to 400 acres per year (EPA 1999).

Undeveloped land provides valuable ecosystem services.

Degradation, ragmentation, or loss o these natural systems

adversely impacts orest ecosystem health and compromises the

ability o orests to provide habitat, clean water, pure air, and other

critical resources upon which we rely.


9/44

7

istorically orests were considered healthy simplyi they supported an abundance o healthy trees.In a broader context, orests are ecosystems

supporting many organisms in addition to trees, and whoseunctions are more inclusive than just human exploitationo its resources. Forest ecosystems provide services tohumans without which we could not live. They puriyour air by capturing pollutants. They provide shade and

windbreaks that regulate and moderate temperatures. Theyprotect waters by puriying and keeping them cool. Whenstorms come, they mitigate the impacts rom fooding.They capture nutrients rom the air, and renew soil ertility.Tree roots adhere to soils and prevent major soil erosionand sediments leaching into streams and lakes. Forestsprovide habitats or game and nongame animals, harbornatural control agents against pests, provide resilience

rom disturbances. And they allow humans to beneteconomically rom recreation, aesthetics, wood harvesting

and other orest products. A healthy orest ensures theprovision o these ecosystem services. A healthy orestsystem is also dynamic in response to natural climatevariability, disturbances, and succession. But changesin structure or unction outside the historical range ovariability may signal stress.

Recent international agreements known as the Montreal

Process Criteria and Indicators o Forest Sustainabilityhave ormed a oundation or describing and measuringorest sustainability across the landscape. Five o theseindicators pertain to orest ecosystem health: biodiversity,productivity, soil and water resources, carbon cycles, and

disturbances. These provide a ramework or describingcurrent conditions and trends in orest ecosystem healthwith particular ocus on studies by the Vermont MonitoringCooperative (VMC).

THE HEALTH OF OUR FORESTS

H BBiodiversity encompasses not only the composition ospecies, but also the complexity o structural eatures withina orest stand and across landscapes. Vermont hillsides area patchwork o orests with trees o various sizes and ages.

This diversity o tree sizes and ages makes orests adaptable,dynamic, better situated to recover rom disturbance, andalso provides a broader range o habitats or otherorganisms. One advisory group o Vermont oresters andecologists suggested that a healthy proportion o tree sizesin a mature orest would be approximately 50 percentsaplings, 30 percent pole-sized trees, and 20 percentsawtimber-sized trees (VTFPR 1999). Two time periods ostatewide orest inventory data show an increasing proportiono trees in the smaller tree category (Figure 4).

Special characteristics o orests can make them suitableas habitat or animal species. Vernal pools, caves, coarse

woody material, and legacy trees are examples o uniquestructural elements that provide habitat or animals andallow greater potential diversity. When animal survey dataare not available, habitat measures can be used as predictorso potential species diversity. VMC data have been valuablein building connections between animal-species diversity

and habitat eatures. Among other examples o this dataare VMCs orest bird survey and moth-host plant database,both o which are discussed in this report.

Composition of Tree Sizes in Vermont Forests

80

60

40

20

0

24.3

8.219.1

7.9

1983 1997

67.5 73

Figure 4: Studies in 1983 and 1997 show an increasingpercentage o Vermont trees are in smaller-size categories.

Source: VTFPR 1999


10/44

8

N- P I P

ermont has been subject to many introductions o exotic insectand disease organisms that have caused damage to orests(Table 1). Some organisms have ecosystem-altering eects,

such as those responsible or Dutch elm disease and chestnut blight.

In other cases the impacts are slower, oering opportunities to developmanagement strategies to mitigate impacts. VMC has been instrumentalin providing ongoing detailed inormation on non-native organisms, suchas pear thrips, gypsy moths, and beech bark disease, which are now wellestablished in Vermont, and has helped in understanding relationshipsbetween these pests and environmental actors. For example, pear thripshave been ound to cause more damage when cold weather slows thedevelopment o sugar maple leaves.

Other non-native insects are moving toward Vermont, and could causesignicant ecological eects. These include the emerald ash borer, with newnds in Quebec; the Asian long horned beetle, a maple pest now in Worcester,MA; and the hemlock woolly adelgid, now in orests in southeastern Vermont.Long-term monitoring by VMC provides baseline data which will help assess

the impact o these insects on host species and associated organisms.Invasive non-native plants, such as barberry, buckthorn, and honeysuckle,

continue to expand northward in Vermont orests, causing negative impacts on biodiversity and orest regeneration.Forest monitoring plots, such as those measured at the VMC research sites, provide a mechanism to survey trendsin invasive plants and their long-term eects on orest health. The North American Maple Project survey resultshighlight the growing incidence o invasive plant species in orests across Vermont (Figure 5). At the VMC sites atMt. Manseld and Lye Brook, which are more removed rom residential areas and their associated plantings o

non-native plants,no exotic invasive plants were ound in a 2005 survey at 20 monitoring plots.

Table 1:This list

indicates

the status onon-native

insects and

diseases in

Vermont.

Source:VTFPR

60

50

40

30

20

10

0

Barberry Buckthorn Honeysuckle Multiflora Rose

Non-native Invasive Plant Species

PresenceonPlo

ts(%)

Figure 5: There is a growingincidence o non-native invasive

plant species on monitoring plots

statewide.

Source: North American Maple Project

V

N- S VJapanese beetle Popillia japonica EstablishedElm lea beetle Pyrrhalta luteola Established

Pine shoot beetle Tomicus piniperda Recently detectedEastern spruce gall adelgid Adelges abietis EstablishedBalsam woolly adelgid Adelges piceae EstablishedHemlock woolly adelgid Adelges tsugae Recently detectedBeech scale Cryptococcus fagisuga EstablishedIntroduced pine sawfy Diprion similis EstablishedBirch leaminer Fenusa pusilla EstablishedEuropean spruce sawfy Gilpinia hercyniae EstablishedMountain-ash sawfy Pristiphora geniculata EstablishedLarch casebearer Coleophora laricella EstablishedGypsy moth Lymantria dispar EstablishedPear thrips Taeniothrips inconsequens EstablishedIntroduced basswood thrips Thrips calcaratus EstablishedSirex wood wasp Sirex noctilio Recently detected

Emerald ash borer Agrilus planipennis Not detectedAsian long horned beetle Anoplophora glabripennis Not detected

N- Scleroderris canker Ascocalyx abietina EstablishedChestnut blight Cryphonectria parasitica EstablishedWhite pine blister rust Cronartium ribicola EstablishedDogwood anthracnose Discula destructive EstablishedBeech bark disease Nectria coccinea EstablishedDutch elm disease Ophiostoma ulmi EstablishedButternut canker Sirococcus clavigignenti-juglandacearum EstablishedSudden oak death Phytophthora ramorum Not detected


11/44

9

Vermont is estimated to be home to 441 species o birds, mammals, amphibians,and reptiles. A majority o these species are dependent on orests or all or part o theirlie cycles. As we struggle to balance procurement o orest products with conservationo wildlie, new models o orest management are emerging that protect specicocus animal species. At VMC research sites, we have documented many orested

species and their associated habitat requirements. Biodiversity audits can help assessthe relative environmentalimpacts o various orestry and land-development practicesand o climate change. While biodiversity in communities is oten seen as desirable,it is important to remember that some ecosystems, such as in bogs or sandplains,may have relatively low diversity but harbor highly valued species that are unusualrom a regional perspective.

Insect Diversity

While the enormous diversity and sheer numbers o insects excites entomologists, thegeneral public is amiliar with only a relatively ew species that have economic or healthimpacts. Comparatively little or nothing is known about other insects. Insects comprise overtwo-thirds o the approximately 2 million known species o living things on the earth, andmillions more species remain to be discovered. There are about as many species o butterfiesand moths on Mt. Manseld as there are breeding bird species in all o Canada!

There are currently known to be approximately 2,000 species o butterfies and moths(Lepidoptera) in Vermont, which refects the great variety o habitats ound here. The long,

varied, and sometimes arduous work that has produced this number involves methodical eldprocedures combined with meticulous record-keeping. Additionally, existing curated insectcollections have been an invaluable source o baseline environmental data, with each specimenvouching or the historical occurrence o a species at a particular time and place. Collectively,this inormation allows us to retroactively track local arrivals and extinctions o various species,and rames the study o the eects o human disturbance and climate change. For severalyears in the 1990s, and again a decade later, Lepidoptera were surveyed at three elevations onVMC sites on Mt. Manseld. These eorts resulted in a count o close to 400 butterfy andmoth species. In the ood-web, Lepidoptera larvae are a primary ood source during the nesting

periods o the majority o birds that breed in Vermont.

What can insect communities tell us about the relative ecological health o an area?Among other things, insects have roles in orests as pollinators, decomposers o lea litter, andas prey or breeding birds. Documenting the insect species living in a given habitat, along withtheir immediate networks o organisms, brings us closer to evaluating the health o that naturalcommunity. Monitoring indicator species may shed light on the vigor o a natural habitat. Forexample,we know that the aquatic larvae o certain species o black fy are associated withclean water, or that given species o springtails occur within a specic pH range.

PForest productivity, usually thought o as growth and abundance, is an endpoint o many

unctional processes o orests that in one way or another contribute to growth. Measures

o orest processes include plant growth (biomass), reproductive success, timing odevelopmental stages (phenology), and nutrient dynamics in air, biota, soil, and water.

Forest biomass is a measure o the eectiveness o the photosynthetic process. Whengrowth exceeds mortality, biomass accumulation increases. But i disturbances impact thebalance o growth to mortality, biomass accumulation decreases. At VMCs Mt. Manseldsite, there has been a decrease in above-ground live tree biomass on the east slope andsummit since 1997 (Figure 6), evidence o the impacts rom a variety o stress events on

orest productivity. These events included the ice storm in January 1998 ollowed by excessivemoisture in the summer o 1998 and marked drought in 1999.

There are as manyspecies o butterfiesand moths on Mt.

Manseld as thereare breeding birdspecies in all oCanada.

Atlantis ritillary


12/44

10

The timing o developmental stages provides abaseline or comparing annual changes and allowsevaluation o stress impacts on unctional processeso plants and animals. When managing orest pests,the timing o developmental stages o pest and host

is essential (see page 23 or a discussion o phenologymonitoring).

S W RThe soils supporting orests play a crucial role

in orest health, providing a myriad o servicesranging rom nutrient recycling to physical support.Characteristics important to orest health include

soil texture, drainage, depth, and ertility. With theexception o soil ertility, these soil characteristicsdont change signicantly over time. Tunbridge soilsare typical o Vermont uplands, and not surprisinglysupport the majority o northern hardwood orests (Table 2). Depth to bedrock or hardpan andsoil drainage aect root growth and availability o soil moisture, and determine areas that will

be most aected by droughts. Forest lands have been altered through time or a wide varietyo uses, and not all orests are growing in sites that represent their ideal growing conditions.

Soil-nutrient availability is a common measure o orest health, and where soil pH, base cations,or aluminum concentrations are abnormal, ecological impacts can occur (see page 34 oncritical loads).

VMC supports a program o research and long-term monitoringo streamfow and water quality dynamics o high-elevation orestedstreams within the Lye Brook Wilderness Area and on the slopes oMt. Manseld. These studies have shown that both the fow o waterand concentration o some solutes such as nitrate are highest duringsnowmelt. As a result, most o the annual loss o these solutes rom

orest to stream system is ound during a relatively short time period

in the spring. This ongoing VMC monitoring will aid the detection oenvironmental change due to changing climate and high-elevationdevelopment such as ski resorts.

C COne o the major greenhouse gases is atmospheric carbon in

the orm o carbon dioxide. Through photosynthesis, CO2

is removedrom the air by trees and orest plants, and stored as carbon in roots,stems, and oliage. Forests play a huge role in carbon dioxide mitigationin Vermont, so knowledge o current carbon storage and release is

essential to learning how to better manage our carbon budget. Carbon

can be stored or long time periods in live tree biomass, below ground in roots, in soils, andin trees harvested or durable wood products. Vermont orests are being considered or uturepolicies aimed at sequestration o additional carbon emissions in attempts to reduce ourcarbon ootprint. In calculating carbon sequestration, researchers must consider a variety ocomplex actors, including amount o carbon stored in orests, rate o carbon accumulation,amount o biomass extracted or uel, biomass used or durable wood products, impacts oorest management on above- and below-ground orest carbon, and disturbances such as

insect deoliation.

160

140

120

100

80

60

40

20

0

Biomass(Mg

/ha)

East West Summit

Above-ground Live Tree Biomass

Years

1993

1997

2001

2005

Natural Community Type Soil Name

Northern Hardwoods TunbridgeCabotBerkshire

LymanPeruMarlow

Rich Northern Hardwoods BucklandVershireDutchess

Oak-hickory GeorgiaStockbridgePaxtonPittseld

Table 2: Common soil

series associated withsome o Vermonts

orest communities, in

order o importance.

Source: Report by the

Governors Task Force on

Climate Change, 2007

Figure 6: At VMCs Mt.Manseld site, there

has been a decrease in

above-ground live tree

biomass on the east slope

and summit since 1997.


13/44

11

G G M

R apidly developing domestic and internationalcarbon markets recognize three general possibilitiesor orest carbon management. These are reorestation/aorestation, avoided deorestation, and improved orest

management (Ruddell et al. 2007). The latter is concerned

with the carbon stored in managed orests, and ocuses on

the concept o additionality or the potential or increasing

net carbon storage over a baseline level. But this has

proved challenging or scientists and orest managers alike,

particularly because o the complex carbon accounting

required to determine the net eects o a particular

management approach (Ray et al. 2009).

Actively managed orests provide carbon sequestration

benets both within the orest ecosystem and in harvested

wood products. Biomass uel produced as a by product o

orest management activities can help oset greenhouse

gas emissions rom ossil uels. Ongoing research isexploring how to design orest management strategies

that optimize storage among these sinks. Rapidly growing,

younger or well spaced orest stands may have higher

rates o carbon uptake, but they have lower biomass per

unit area compared to older or less intensively managed

orests (Figure 7), and thus actually store less carbon than

high biomass orests with lower or stable rates o carbon

uptake (Harmon and Marks 2002). Research has shown

that as orests age they store more carbon, due to very high

levels o accumulated above and belowground biomass

(Keeton et al. 2007; Luyssaert et al. 2008). Forested

landscapes recovering toward an older, higher biomass

condition will store much higher quantities o carbon thanlandscapes dominated by young to mature hardwood

orests (Rhemtullaa et al. 2009). Dierent management

approaches (requency and intensity) result in dierent

amounts o average carbon storage over the long term.

Thus the choice o harvesting approach directly aects

not only emissions osets but also long-term carbonstorage dynamics.

Research at UVM by VMC cooperators has used

simulation modeling to examine the impact o harvesting

requency and proportion o post-harvest structural

retention on carbon storage and the signicance o

including harvested wood products in carbon accounting

(Nunery and Keeton, in review). Carbon dynamics were

simulated under nine orest management scenarios,

spanning a range o increasing structural retention

and decreasing harvesting requencies, including no

harvest. The simulations incorporated carbon ux

between aboveground orest biomass (dead and live

pools) and harvested wood products. The results

suggest that intensied regeneration cutting reducesnet carbon storage. Conversely, extended rotations or

entry cycles, high levels o post-harvest retention, and

practices avoring production o durable wood products

enhance average storage over multiple rotations or

entry cycles. The highest levels o storage are actually

achieved by passive management, even actoring in the

oregone storage in wood products. These conclusions

are valid only so long as the analysis does not include

the greenhouse gas emissions that would result rom

substituting non-wood construction materials or wood

i production o the latter were reduced. Other work has

shown that actoring in substitution eects can make

some intensive management scenarios comparable tothe least intensive in terms o net carbon sequestration,

depending on the assumptions built into the analysis

(Malmsheimer et al. 2008).

TotalCarbonS

tored

Stand Development Over Time

Figure 7: This gure shows carbon sequestration andstorage in relation to orest stand development. Note

that the highest rates o uptake occur in early to mid

stages o development, but the greatest levels o storage

are achieved late in development, resulting in a

substantial carbon reservoir.

Source: Jared Nunery and Bill Keeton, UVM


14/44

12

The estimated annual,statewide accumulation o CO

2

in orests is 9.63 million metrictons o carbon dioxide equivalent)(Table 3). Keep in mind that in1990, Vermont CO

2emissions

were 8.1 million metric tons,

and by 2005 had increased to9.1. Without emission-reductionpolicies, emissions could grow to10.67 million metric tons by 2030,beyond orest-sequestration rates.

The two major carbon pools in orests are live trees andsoil. Forests that continue to increase live tree biomass areconsidered sinks or atmospheric carbon. When the rateo sequestration decreases to a point where net growth isless than mortality and decomposition, such as in areas oorest decline, orests become a source o carbon dioxide

emission. The VMC plot data shows that some locations onMount Manseld may currently be a source o carbon dioxideemissions, due to drought-induced mortality and a trendtoward decreasing biomass. This, however, could be reversedas existing trees grow and new trees replace dead trees.

Soil carbon is less well studied. Vermont estimates maybe low because temperate orests are estimated to store nearly

double that o above-ground vegetation. Most o the soilcarbon in Vermont is organic carbon, allowing estimates o

soil carbon based on organic matter content. VMC researchersassembled a map o orest soil carbon or Vermont (Figure 8);areas o high or low carbon may suggest uture guidelinesor managing soil carbon.

DForest health monitoring measures the ability o trees to

recover rom damages inficted by natural and anthropogenicdisturbances. Natural disturbances are an ecologically

important and intrinsic part o Vermonts orested ecosystems. They shape the types, quantities,and spatial distributions o habitats and strongly infuence successional processes. Incontemporary ecology, natural disturbances are viewed as a subsidy to the system, creatingcritical habitat structures and driving a host o ecological processes, including soil and nutrientturnover, organic matter recruitment into streams, and carbon storage dynamics. But whendisturbance dynamics are perturbed by humans (or example, when peoples actions contributeto severe fooding or large-scale insect outbreaks), then deleterious stress can be induced.Disturbances also interact with human-induced stressors, such as acid deposition and climatechange, in determining trajectories o orest ecosystem change (North and Keeton 2008).

Vermont Forests Stored Carbon Annual

(MMt) Accumulation

o CO2 (MMt)

Soil 139 0.7

Forest foor 45.7 0.5

Down dead 12.2 0.4

Understory 3.2 0.03Standing dead 11.4 0.3

Live trees 172.2 6.3

Wood products 1.4

T 383.7 9.63

Table 3: Estimates o carbon stored in Vermont orestsand the annual removal o CO

2rom the atmosphere

through orest sequestration.

Figure 8: This map o

orest soil carbon inVermont, assembled by

VMC researchers, may

help develop guidelines

or managing orest

carbon in the uture.

Source:Wilmot et al. 2008

V F S C


15/44

13

A variety o natural disturbance agents, including wind, ice,insects, ungal pathogens, beavers, foods, and re, have sculptedour orested landscapes or centuries. Events that create gaps inthe canopy are the most common type o disturbance in Vermontsorests. Disturbance gaps usually involve death or damage to

individual or small groups o trees. Depending on size andorientation, gaps can result in regeneration o intermediate to shadetolerant species, release o advanced regeneration, or competitiverelease and accelerated growth in proximate overstory trees.

In 1985, surveys o Vermonts hardwood resources showednearly 14,000 acres o dead trees (Figure 9). Although subsequentresurveys showed that acres o dead trees decreased and percento healthy trees improved to 90 percent or better, concern aboutsugar maple tree health across the regioncaused potentially by

impacts o acid deposition and the ill eects o tapping trees ormaple syrup productionled to the establishment o a Canada-United States sugar maplehealth monitoring program (NAMP). In Vermont, one o the monitoring sites was at the base

o Mount Manseld.Sugar maple health monitoring has

provided solid inormation on trends in stress

events and recovery or this prominent treein Vermont orests. While initially this surveyshowed areas o tree decline, with only 81

percent o sugar maples in Vermont plotsconsidered healthy, tree health improved inthe early 1990s (Figure 10). Tree health dippedagain in recent years ollowing an outbreak oorest tent caterpillar.

In 1990, a systematic orest health detectionprogram started in New England and grew tobecome the national Forest Health Monitoring

program, aimed at detecting emerging

regionally signicant orest health problems.We have adopted key ecosystem methodsrom this program or use on many o ourVMC monitoring plots. VMC provided a uniqueopportunity to co-locate these orest health

measurements with those o atmospheric, weather, wildlie, water, and soils conditions, whichhas improved our understanding o relationships among environmental changes, orest health,and ecological dynamics (see Ozone, page 36).

A massive ice storm in

1998 devastated large

portions o Vermonts

orests.

17,500

14,000

10,500

7,000

3,500

0

1985 1990 1995 2000

Acres of Hardwood Mortality in Vermont

Year

Figure 9: In 1985, a survey o Vermonts

hardwood resources showed nearly14,000 acres o dead trees. In later years

this acreage decreased dramatically.

Source: Kelley et al. 2002

25

20

15

10

5

0

Sugar Maple Health

Average %

1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007

Dieback

Foliage Transparency

Mortality

Figure 10: Sugarmaple health

monitoring has

provided long-term inormation

on trends in stress

events and recovery.

While initially only

81 percent o sugar

maples were healthy,

tree health improved

in the early 1990s.

Source: Vermont Plots,

NAMP

Forest tent caterpillar


16/44

14

Precipitation is one o the key drivers oorest health, both directly and indirectly. Treesneed adequate moisture or growth, but lowprecipitation has also been correlated with risingpopulations o insect deoliators. Periods o poorsugar maple tree health have corresponded withbelow-normal precipitation over the past twodecades. Following the 1999 and 2001 droughts,orest tent caterpillar populations exploded,

resulting in extensive deoliation. Stress rom avariety o disturbances has aected sugar maplehealth at Mt. Manseld and around Vermont asseen in the percent o trees with thinner thannormal oliage (Figure 11).

Monitoring has been instrumental indetermining thresholds or tree recovery. Periods o stress oten lead to crown dieback, but treeshave the ability to recover i the stresses abate. Fertile sites high in calcium tend to recover more

quickly. This ability also varies with species. Sugar maple is good at recovering; yellow birch hasa moderate ability to recover, but paper birch has poor stress recovery. This inormation hashelped orest managers determine how and when to thin orests to maintain healthy, vigorous

trees, and was especially helpul in salvage cutting ollowing the destruction rom the 1998 icestorm (Kelley et al. 2002). Tree recovery at VMC sites has ollowed this same trend; sugar maplerecovery rom the ice storm and rom orest tent caterpillar deoliation has been good, but whitebirch recovery rom ice damage and drought has not been as successul.

At the VMC study sites, weather actors play a signicant role in shaping the growingconditions o orests. Mt. Manseld has elevations ranging rom 1,300 to 4,300 eet and Lye

Brook Wilderness Area peaks at nearly 3,000 eet.Winter storms are severe, with high winds and icecovering trees. Soils are quite shallow in portionso upper elevation orests. Also, air at these upperelevations is laden with high amounts o acidiccompounds, ozone, and mercury. So monitoring

the health o these orests can show the mostextreme orest impacts rom stress events, but

can also provide early indications o potentialproblems that will aect a wider area oVermonts orests.

Forests o the high-elevation spruce-rzone on Mt. Manseld have been more proneto mortality than other locations. The balsamr-dominated orests consistently have highdieback and damage rom broken branches.Annual monitoring has also shown that heavy cone-producing years, while beneting squirrel

populations, is detrimental to crown health and indirectly to bird reproduction, as squirrels are

predators o bird eggs. Birch trees are particularly vulnerable to drought. On the east slope oMt. Manseld, birch condition has declined since the severe drought o 1998-99 (Figure 12).

50

45

40

35

30

25

20

15

10

5

0

1992

Percent of Trees with High Dieback

1993

19

9419

95

1996

19

97

1998

19

99

2000

20

01

2002

20

03

2004

2005

2006

20

07

2008

Balsam fir

Birch

Figure 12: This gureindicates dieback o

birch and balsam r

on Mt. Manseld. Adecade o balsam r

recovery ollows a past

disturbance. Birch

trees are particularly

vulnerable to drought,

shown here in the

decline o birch since

the severe drought o

1998-99.

Source: Sandy Wilmot,VTFPR

50

45

40

35

30

25

20

15

10

5

0

1988

Percent of Sugar Maple Trees on Monitoring Plots with Thin Foliage

Pear Thrips Ice Storm

Drought Forest Tent Caterpillar

1989

1990

19

9119

9219

9319

94

1995

1996

19

97

1998

19

99

2000

2001

2002

2003

20

04

2005

2006

20

07

Figure 11: Stresses roma variety o events have

aected sugar maple

health. Following the

1999 and 2001 droughts,

or example, orest tentcaterpillar populations

exploded, resulting in

extensive deoliation.

Source: Vermonts Plots,

NAMP


17/44

15

orest managers in Vermont must contend withmyriad hot button issues. These include how to deal

with exotic diseases and insects, adapt to climate change,

saeguard riparian systems, minimize impacts associated

with orest roads, manage competing recreational interests,

and conserve orest biodiversity. Keeping working orests

economically viable, conserving open space, and

discouraging parcelization and sprawl are major concerns.

But 21st century oresters also ace new opportunities, such

as growing interest in community-based orestry, orest

certication, rapidly developing carbon markets, and rising

demand or sustainably produced biomass uels. These

opportunities may create economic and other incentives

or sustainable orest management, but also require

balancing tradeos between competing resource values.

An example is the inherent difculty o how best to allocate

biomass among uses such as on-site carbon storage,wood products, uel, and habitat structure.

A central challenge in sustainable orest management

has been determining the best mix o management

approaches most capable o providing a broad array o

ecosystem unctions while meeting landowner objectives.

VMC scientists are conducting research on a promising area

known as disturbance based silviculture, which emulates

naturally occurring orest processes (Keeton 2006).

A general nding o this research is that late-

successional characteristics in northern hardwood

including vertically complex canopies and gapscan be

promoted through a variety o modied silvicultural

approaches. But these management techniques are lesseective in other ways, tending to signicantly inhibit certain

stand development processes, such as recruitment o large

trees, downed coarse woody debris, and the highest levels o

biomass and carbon storage. The results signal that

treatments can be modied to retain and even enhance

important elements o stand structural complexity, but o

course this involves tradeos in terms o reduced harvest

volumes (Figure 13).

The VMC-sponsored Forest Ecosystem Management

Demonstration Project (FEMDP) has also shown that low-

intensity, disturbance-based management can provide an

intermediate level o carbon storage, providing a margin o

enhanced on-site carbon sequestration compared toconventional selection harvesting. Aboveground biomass is

predicted to increase over the next 50 years under all the

treatments, including controls. None o the experimental

stands is likely to attain the biomass they would have without

treatment, but some techniques are projected to attain 91.4

percent o the biomass levels o untreated stands.

FEMDP researchers have monitored a variety o wildlie

as indicators o biodiversity responses to sustainable orest

management. As predicted, responses to the silviculturaltreatments vary according to the habitat associations o

dierent groups o species. For instance, some early

successional bird species appear to have beneted rom the

variably sized openings created by group selection logging,

while all the treatments have been eective in maintaining

the habitat needed by interior dwelling and late-successional

birds (Strong, unpublished data).

There are clear economic tradeos involved in modiying

silvicultural treatments to promote stand structural complexity

(Keeton and Troy 2006). FEMDP assessments examined

timber-related revenue only, whereas a more complete

economic analysis might include other potential revenue

sources, such as carbon credits.The prot margins incurred

by all the treatments were highly sensitive to site quality andmarket conditions. Where these are poor, lower intensity

harvesting may generate only enough prot to cover expenses.

This might be acceptable in a limited number o settings,

or instance where disturbance-based approaches are employed

or restoration purposes in reserves. For commercial harvests,

however, the experimental approaches would be marketable

only where site quality is moderate to high and market

conditions are avorable. Under those conditions the

experimental treatments oer alternatives that provide

revenue rom low-intensity harvest while also meeting

ecological management objectives.

R S F M

F

P r e - H a r v e s t

P r e - H a r v e s t

P o s t - H a r v e s t

P o s t - H a r v e s t

Single-Tree Selection Unit

Structural Complexity Enhancement Unit

Figure 13: Visualization o stand structure changesassociated with two o the experimental treatments in

the VMC Forest Ecosystem Management Demonstration

Project.

Source: Keeton 2006

PRE-HARVEST

PRE-HARVEST

POST-HARVEST

POST-HARVEST


18/44

16

Biomonitoringdata collected onmountain streamsbelow ski resortsshow that increased

sediment andfuctuating pH canaect the productivityabundance, andspecies richness omacroinvertebrates.

Ski Resorts and Land-Use Disturbance

Disturbances caused by conversion o upland orests to developed uses may have moreserious environmental implications than at low elevations. As Vermont ski resorts expand anddiversiy activities over our seasons, their ecological impacts may be intensiying. Mountain

ecosystems are also increasingly subject to other disturbances and stresses such as climatechange, mercury deposition, acid precipitation, and development o wind and communicationtowers. VMC-supported wildlie research has ocused on three aspects o mountain

development: direct habitat loss, ragmentation, and modication. Hydrologic and aquaticstudies have examined the role o mountain development on streamfow, water quality, andaquatic biota.

The response o wildlie species to orest ragmentation and loss is dictated by actorssuch as home range size, sensitivity to habitat edge eects, and gap-crossing ability. Theoretical

modeling o bird species on two existing Vermont ski resorts, Stratton Mountain and MountManseld, showed dramatic decreases in population sizes as ragmentation and edge eectsincreased (Strong et al. 2009). Modeling habitat requirements, using current ski resortmanagement scenarios, shows that species with one-hectare territories declined by 32-41percent, while population declines in species with ten-hectare territories ranged rom64-73 percent. These results underscore the need to investigate actual impacts o ski resortdevelopment on wildlie, in particular high-elevation orest birds like Bicknells thrush.

Research on songbirds has repeatedly shown that increased habitat ragmentation causesedge eects which can lead to higher rates o nest predation and lower rates o nest survival.

Because ski trails and associated work roads ragment and increase the amount o edge habitat,an important question is whether these modications aect the nesting success o Bicknellsthrush. VMC researchers examined potential dierences in nest predation and adult survivor-ship on ski resorts compared to natural orest areas on Manseld and Stratton (Rimmer etal. 2004). Overall there was no strong evidence or a ski resort eect on nest predation orsurvivorship. There was some evidence that male thrushes may be more vulnerable to predationwhen crossing open ski trails. Radio telemetry data indicate that Bicknells thrushes tend toavoid crossing large openings. Other species may also be reluctant to cross open ski trails,

as shown in research involving orest beetles (Strong 2009) and six species o songbirds(Holmgren 2002).

Mountain watersheds are high energy settings, where water, solutes and sediment moverapidly over steep slopes and thin soils. Decades o study in orests o the northeastern U.S.and elsewhere indicate that logging and road construction aect annual water yields, peakfows, sediment production, water quality, and aquatic habitat quality. The eects o ski resortdevelopment, however, are not well known. In 2000, a team o VMC cooperators established a

Aerial inrared

photography showing

an increase in road

inrastructure and

land-use changes

in Charlotte over a

15-year period.

Source: Kelley et al. 2002

1985 2000


19/44

17

watershed study on Mt. Manseld to examine the hydrologic eects o ski resortdevelopment. The study uses a paired-watershed approach to compare streamfow,water chemistry, and sediment yields or two adjacent watersheds on the easternslopes o Mt. Manseld (Wemple et al. 2007; Shanley and Wemple 2009). Evenater accounting or small dierences in watershed size and articial snowmaking,

study results show that water runo rom the ski resort watershed consistentlyexceeds that o the unmanaged watershed to a greater extent than orest harvestingincreased runo over unmanaged orests in regional watershed studies. Thegreater runo appears to result rom the combined eects o the more prodigioussnowall in the ski-resort watershed and to dierences in snowmelt delivery tostreams during spring runo, and has important implications or storm watermanagement in mountain development projects. Annual sediment yield rom theski-resort watershed exceeds that rom the unmanaged watershed by roughly threetimes (Figure 14), with much larger dierences documented during periods o

construction and ground disturbance. Annual chloride yield is ten times higher inthe developed watershed, presumably due to road salting, relative to the control(Figure 15).

VMC-sponsored research on ski resort development also ocuses on aquaticbiota. Biomonitoring data collected on mountain streams below ski resorts showthat increased sediment and fuctuating pH can aect the productivity, abundance,

and species richness o macroinvertebrates. Increased fows oten will cause ascour eect temporarily decreasing macroinvertebrate abundance, results that areseen in monitoring data across the state.

The three species o stream salamanders which inhabit the mountain orests o Vermontserve as useul bioindicators o stream habitat quality. Salamander abundance and body sizeswere quantied within seven Vermont ski resorts and in adjacent undisturbed orest areas,including Mt. Manseld (Hagen 1998; Strong et al. 2009). Ski resort streams supportedsignicantly lower populations o spring salamanders and northern dusky salamanders, andbody lengths o northern dusky salamanders were shorter within ski resorts. These dierencesmay have resulted rom clearing streamside vegetation and increased siltation rates instreams within ski resorts.

VMC-supported research has shown that the eects o upland development, when

reerenced against traditional orest practices o logging and road construction, have provedto be larger than expected. Some o these eects can be mitigated through good managementpractices, including storm water detention structures, waterbars on ski trails, and increasedriparian buer widths. Other eects are an inevitable outcome o habitat ragmentationassociated with development o the mountain landscape.

Fragmentation Eects on Reptiles and Amphibians

Land conversion and ragmentation are key disturbances that adversely aectthe ability o animals to move saely through the landscape. As a result othe statewide reptile and amphibian studies unded by VMC, we have rened

our knowledge o the distribution o all o Vermonts reptiles and amphibians

and the eects o habitat ragmentation on these species. One o thesespecies, the eastern ratsnake, is among the largest snakes in the UnitedStates, commonly reaching six eet in length. The eastern ratsnake has anisolated northern population and a connected population in western RutlandCounty. The northern population on the Monkton/New Haven/Bristol borderis entirely disconnected rom any other eastern ratsnakes; hence, thereis no introduction o new genes into the population and no possibility o

recolonization ater a local population extirpation. Consequently, it is at amuch greater risk o permanent loss than the Rutland County population.

250

200

150

100

50

0

Annual Suspended Sediment Yield

WY01 WY02 WY03

150

100

50

0

Annual Chloride Yield

WY01 WY02 WY03

Ranch Brook West Brook

Ranch Brook West Brook

Wood turtle

Figures 14 and 15:In a paired-watershed

study at Mt. Manseld

conducted in water

years 2001-2003,

both annual sediment

yield and annual

chloride yield were

higher on a ski-resort

watershed than on an

unmanaged watershed.

Source: Wemple et al. 2007;Shanley and Wemple 2009


20/44

18

Among the best known migrating wildlie in Vermont are those specieso amphibian that breed in the early spring. With the rst warm rains o lateMarch and early April, thousands o spotted salamanders and wood rogs thathave spent the winter in upland deciduous orests, head to the nearest beaverponds, vernal pools, and swamps to breed and lay their eggs. VMC-unded

work has discovered a ew, large, remaining populations o the blue-spottedsalamander. One o these populations currently crosses a major shortcut to theWilliston big-box shopping malls. As a result, hundreds o adult blue-spottedsalamanders are killed on this road every spring. Eventually the amount omortality on the road will surpass the ability o the population to replace them,and the population will disappear. Another amphibian, the eastern newt, relieson a contiguous mosaic o oten shiting ponds and orested uplands or its liecycle. As these ponds and orests become isolated rom each other by orest ragmentation,the newts become increasingly at risk.

Wood turtles exempliy another conservation issue aecting long-lived species. Woodturtles may live 30 years or more and do not become sexually mature until reaching about 14years o age. Their survival as a species depends upon the turtles laying eggs or many years.The long-lived strategy worked well or wood turtles until the introduction o cars, mechanizedhaying equipment, and turtle collectors. Consequently, both their longevity and their terrestrialbehavior put them more at risk rom increased development, habitat ragmentation, and human

population growth.Another example o the impact o changing orested landscapes on reptiles is loss o

early successional habitat. Both smooth greensnakes and North American racers preer open

grasslands or a mix o shrubs and grasses. Historically these might have been extensive beavermeadows, food plains, or areas cleared by rockslides, hurricanes, or other natural events. Ashilltop arms were abandoned, open areas rst returned to orests, and now many are beingdeveloped. Most o the lands that remained open were maintained by regular mowing, or usedas cropland. The machines that keep these lands open today have become aster and more

ecient over the years. Wildlie o all kinds ismowed, raked, and baled along with the crops.As a result, smooth greensnakes and North

American racers no longer inhabit cropland

or regularly mowed and baled areas. Theyare, however, ound along open power lines,cleared margins o roadways, pastures (keptopen by animals), wet elds, and elds keptopen by occasional brush-hogging to maintain

views. Consequently, populationso the smooth greensnake areincreasingly dicult to nd. We know

o only one recent populationo North American racers and eventhat one may have disappeared inthe last two years.

Blue-spotted salamander

Smooth greensnake

Eastern rat snake

VMC-unded workhas discovereda ew, large,remaining

populations othe blue-spottedsalamander.Eventually theamount omortality on theroad will surpassthe ability o thepopulation to

replace them.


21/44

19

R

Nearly two decades o VMC-supported research and monitoring provides a rich pictureo the health o our orests and a window into things to come. Strengths and weaknessesin the health o our orest ecosystems have been highlighted in this report. Productivitymonitoring indicates stresses caused by air pollution, extreme weather events, and perhapschanging climate conditions. Our orests produce an abundant supply o clean water, butstudies suggest that development will produce impacts on fows and water quality that will

have measureable eects on aquatic organisms. Biodiversity in our orests is high, but VMCstudies show clear eects o a landscape increasingly pressured by a growing population andland-use practices that consume and ragment natural habitats.

VMC researchers studying orest-health issues recommend the ollowing:

Continuetostudycarbondynamicsinmanagedandunmanagedforests,andtheir

relationship to long-term orest recovery rom historic land uses, anthropogenic stress,natural disturbance dynamics, and orest management.

Investinequipmenttobetterunderstandcarbonuxandinteractionsbetweencarbonand other atmospheric pollutants as climate changes.

UtilizeVMCexpertiseanddatatoaddresstheecologicaleffectsofexpandingbiomassharvesting or energy.

Createdemonstrationareasforforestmanagerstomeasureforestcarboncyclingandunderstand carbon accounting and management options.

Continuemonitoringtheresponsesofterrestrialandaquaticspeciestodevelopmentpressures leading to habitat ragmentation.

CollectbaselinedataonnewhumanandanimalhealthrisksemerginginVermont,including especially the deer tick, a vector o Lyme disease.

Monitornaturaldisturbanceimpactstobetterunderstandbaselineecosystemdynamicsand evaluate regime changes related to global climate disruption.

UtilizeVMC-supportedwatershedresearchtoinformstatepermittingstandardsfornewmountain development projects.

Providedatatoinformguidelinesforskiresortsandothersconductinghabitat-mitigation

eorts to maintain or restore ecosystem structure and unction.

VMC I D I B

ndiana bats are listed as an endangered species at state andederal levels. Populations in Vermont depend on large old sugarmaple trees or nesting and rearing their young. A recent population

explosion o orest tent caterpillars deoliated thousands o acres osugar maple orest. Proposed control eorts to protect sugar maple

stands included aerial applications o a bacterial biological control agent,Bacillus thuringiensis (Bt). Because Bt is known to kill Lepidoptera larvae ingeneral, concerns were raised about the eects o such treatments on thebats ood supply, which would have placed an additional stress on batsduring a critical lie stage. Data on moth presence and abundance,generated through VMC and other studies, were used to help time theaerial sprayings so that eects on the Indiana bat populations wouldbe minimized.

I

Indiana bat

Nearly twodecades oVMC-supportedresearch andmonitoringprovides a richpicture o thehealth o ourorests.


22/44

S

20

WEATHER AND CLIMATE IN VERMONT

ituated just south o the 45th parallel, Vermontexperiences a humid, continental climate that

is characterized by a high degree o variability. Thestates latitude and location relative to air masses androntal systems that originate to its northwest, west, andsouth are key actors in both the weather fuctuations thatare observed seasonally and annually, as well as the natureo the storms that move across it. Precipitation is equallydistributed throughout the year and the cloud shield thataects most o the region makes Vermont one o the

cloudiest places in the United States.Weather and climate reer to two very dierent

phenomena. Weather describes the condition o theatmosphere (or example, temperature, precipitation,cloud cover, and humidity) over a short time rame ominutes to about a week. Climate, on the other hand, reersto the longer-term averagesmonths to millennia andlongero the variations in the atmosphere, biosphere,

and hydrosphere over time. Climate variability incorporatesthe naturally occurring fuctuations in the atmosphere overthese long time periods, while climate change reers toa long-term change in the statistics o climate variables(such as winds and temperature) due to either naturalclimatic processes, changes in earth-sun characteristics,or anthropogenic mechanisms (American MeteorologicalSociety 2000).

Natural climatic hazards that plague Vermont includetemperature extremes, fooding, drought, tornadoes,

damaging winds, severe thunderstorms, winter storms andorest res. Each hazard has seasonal characteristics and

temporal cycles, with some occurring more requently incertain decades than others. Hazards can be exacerbated bythe states terrain and mountain barriers (its orography), inparticular the north-south trending Green Mountains andTaconics. Orographic precipitation reers to the enhancedprecipitation totals that occur when a storm system is

orced to rise as it encounters a mountain barrier. This isoten observed across Vermont and can lead to foodingepisodes in the summer or areas o increased snowallaccumulation in the winter. On a local and regional scale,

Vermonts mountains and valleys also aect the unnelingo wind fow, the creation o cold/rost hollows in valleys,and the line between reezing precipitation and rain or snowduring complex winter storms. These terrain infuences aretranslated into the distribution and diversity o species types

as well as the location and magnitude o storm damage onorests (Dupigny-Giroux 2002).

M TIn Vermont there is a saying that one extreme ollows

another. This is particularly true or droughts and foods.Very severe droughts are rare and tend to be statewide,spanning a number o years. These include the severedroughts o the mid-1960s, 1998-1999, and 2001-2002all were noteworthy in terms o their eects on the statesorests. The 1998-1999 event aected 85,000 acres (34,425hectares) statewide with symptoms such as lea scorch, leayellowing, and early lea color. Less severe droughts occur

more requently and tend to be localized in extent. Speciesthat are susceptible to drought include red and sugar maple(Dupigny-Giroux 2002). Temperature extremes can occurin every season, including extreme cold and rost duringthe summer which can be detrimental during the growingseason. In the spring, marked fuctuations ollowingbudding can infuence fowering in species such as crabapples. In 2001, spring temperatures varied rom at least

90 degrees F to about 20 degrees F. This accelerated theproduction o apple blossoms, which were then destroyedby the low nocturnal temperatures. Moisture extremes

can be conducive to insect outbreaks as well as diseasessuch as tar spot that repeatedly struck Norway maples in2007 and 2008.

Storms and other severe weather can act asdisturbances in orested ecosystems, the most noteworthyo which in recent decades was the ice storm o January

1998, which damaged more than 951,000 acres in Vermontalone. Other stressors such as drought and hurricane-induced rainall have also caused physical and chemicalchanges in plant response. When these stressors and


23/44

21

disturbances occur consecutively or coincidentally, they raise questions aboutlong-term orest health and viability.

Meteorological observations are taken at six Vermont Monitoring Cooperative(VMC) sites. The lowest in elevation are Colchester Ree (125 eet or 38 meters)and Diamond Island (148 eet or 45 meters), located on Lake Champlain. Both

stations report 15-minute averages with Colchester Ree beginning in July 1996and Diamond Island in May 2004. In September 1996, the station on the westernslopes o Mt. Manseld began operations at an elevation o 2,800 eet (853meters). A second station, also at 2,800 eet on the eastern side o Mt. Manseld,became operational in July 1999. Fiteen-minute data are available or these stationsas well as or the Proctor Maple Research Center Air Quality site (1,309 eet or399 meters). Finally the National Weather Service supervises daily records at thesummit o Mt. Manseld (4,300 eet or 1,310 meters), which has been in operationsince 1954.

Daily readings o temperature and relative humidity taken at the ColchesterRee station versus Mt. Manseld West highlight the stations physical andgeographical dierences (Figures 16 and 17). The moderating infuence o LakeChamplain is clearly observed at Colchester Ree in contrast to the more continental andhigher elevation on Mt. Manseld. Variations in relative humidity between these two sites aredetermined by both the temperature and water vapor pressure o air and largely refect the

dierent air characteristics at the sites. The range o relative humidity values is larger at

40

30

20

10

0

-10

-20

-30

1997

Air Temperature Colchester Reef

1998

19

99

2000

2001

20

02

2003

20

04

2005

20

06

2007

20

08

2009

Year

AirTemperature(C)

30

20

10

0

-10

-20

-30

-40

1997

Air Temperature Mt. Mansfield

1998

19

99

2000

2001

20

02

2003

20

04

2005

20

06

2007

20

08

2009

Year

AirTemperature(C)

Figure 16: Daily average air temperatures atColchester Ree (top) and Mt. Manseld West.Source: Christopher Still

100

90

80

70

60

50

40

30

2010

0

1997

Relative Humidity Colchester Reef

1998

19

99

2000

2001

20

02

2003

20

04

2005

20

06

2007

20

08

2009

Year

RelativeHumidity(%)

Relative Humidity Mt. Mansfield

100

90

80

70

60

50

40

30

20

10

0

1997

1998

20

00

2001

20

02

2003

20

04

2005

20

06

2007

20

08

2009

Year

Relativ

eHumidity(%)

Figures 17: Daily average relative humidity at ColchesterRee (top) and Mt. Manseld West.Source: Christopher Still

The Colchester Ree

monitoring station.


24/44

22

Mt. Manseld than it is at Colchester Ree, with substantially more100 percent relative humidity observations at the ormer site. Also,while the mean daily relative humidity is rarely below 50 percent atColchester Ree, it requently dips below this threshold at the Mt.Manseld station.

Cloud data comprise another meteorological elementmeasured at these stations. Clouds infuence several environmentalactors important or orest carbon and water cycling and oresthealth. For example, clouds are strong determinants o suraceclimate, particularly intercepted solar radiation (insolation), airtemperature, and relative humidity. Clouds diuse sunlight. Studieso orests have documented how increasing this so-called diuseinsolation can increase canopy photosynthesis up to a point. Thereason is thought to be due to enhanced photosynthesis o leaves

deep in the canopy that are otherwise shaded by upper-canopyleaves. Clouds also decrease radiant heating and thus temperatureso upper canopy leaves. Finally, increased cloudiness is alsoassociated with higher relative humidity via decreases in air and leatemperature and increases in specic humidity.

As a result o all these processes, temperate broadlea orests

oten have the highest photosynthesis rates under partly cloudyconditions, as they benet rom lowered temperatures, higherrelative humidities, and increased diuse insolation (Freedman et

al. 2001; Min and Wang 2008; Still et al. 2009). However, cloudscan also negatively impact orests through delivery o acidityand pollutants rom cloudwater deposition. Cloudwater is otencontaminated with pollutants like mercury and other trace elements. Given the importanceo clouds or orest processes and health, we analyzed long-term data on cloud requencyand height rom the Burlington International Airport. Seasonal cycles o cloud requency areshown in the two charts in Figure 18, which indicate clearly how cloudy the Burlington area is,with the highest cloud requency in winter and the lowest requency in the summer months.

Cloud data going back to the late 1940s document an apparent downward trend in the

requency o cloudy periods observed in Burlington starting in the mid-1990s and continuingto the present. Notably, when we examine the requency o clouds with bases below 1,000meters over this same time period, no downward trend appears,so the variation must be driven by higher elevation clouds.Interestingly the downward trend in cloud requency may underliethe insolation patterns observed at Colchester Ree. As can be seenin Figure 19, there is an increase through time in the summertimemaximum insolation values measured at Colchester Ree. This is

exactly what would be expected rom declining cloud cover overthis period, with reduced refection, scattering, and absorption osolar radiation rom cloud droplets.

In order to place these observations into perspective, it

is useul to look at averages over the entire western region oVermont or an extended period o time. Again, climate variabilitycomes to the ore with marked temperature and precipitationfuctuations over the last century at both a regional scale (westernVermont) as well as statewide. Several droughts o larger

magnitude and intensity than those observed in the VMC period o record are noted onFigure 20, as are the decades that have been warmer and colder than those o the 1998-2008time rame.

Figure 18: Cycleso cloud requency

at the Burlington

International Airport.

Source: Christopher Still

0.9

0.8

0.7

0.6

0.5

0.4

0.3

0.2

0.1

0

Average Seasonal Cycle of Cloud Frequency

Month

C

loud

Frequency

1 2 3 4 5 6 7 8 9 10 11 12

Mean Monthly Frequency Clouds < 1000mMean Monthly Frequency All Clouds

0.8

0.7

0.6

0.5

0.4

0.3

0.2

Year

Cloud

Frequency

1949

1952

1955

1958

19

6119

64

1967

1970

1973

1976

1979

1982

1985

1988

19

91

1994

19

9720

00

2003

2006

Annual Mean Cloud Frequency Since 1949

600

500

400

300

200

100

0

Insolation Values at Colchester Reef

Insolation(W/m2)

1996

1997

1997

1997

1998

1999

1999

2000

2000

2001

2002

2002

2002

2003

2003

2004

2004

2005

2005

2006

2006

2007

2007

2008

2008

2009

Date

Figure 19: There is anincrease through time in

the summertime maximum

insolation values measured

at Colchester Ree.

Source: Christopher Still


25/44

23

F P SForests are dynamic. Thus, understanding and measuring

what is normal can be challenging, requiring a long-timecommitment. One measure o orest processes is the timingo spring events such as tree lea and fower development,ephemeral plant fowering, and pear thrips (a orest insectpest) emergence and eeding. Over the past 18 years, sugar

maple lea and fower development have been monitoredannually, and other spring phenological events have beenmonitored periodically, at Mt. Manseld, Lye Brook, and other

locations, as indicators o orest health.Forests in spring are teeming with activity as trees, plants,

and animals come alive rom their long winters dormancy.Everything happens quickly and the timing o eventsdetermines an organisms survival and propagation. Herbaceous ephemeral plants (plants thatare only seen in the spring) are a clear example o a quick, well timed orest process. Sunshinepenetrates orest canopies that havent yet produced their leaves, warming the orest foor.This provides an opportunity or plants that normally live in the shade o orest trees to takeadvantage o the warmth and open canopy to quickly emerge, gather sunlight or energy,

fower, and set seeds. By the time tree leaves have come out, these plants are nished theircrucial lie stages and retreat into dormancy once more. The timing o these events has beenmonitored over the last 18 years at the base o Mt. Manseld in a sugar maple-dominatedorest, providing a baseline or monitoring change over time (Table 4).

Pear thrips was discovered as a new sugar maple pest in 1987, and in 1988 thrips deoliatednearly 250,000 acres o orestland inVermont. This tiny insect emergesrom the soil in the early spring and

searches or open sugar maple budsto enter and eed upon. I spring buddevelopment is rapid, thrips havelittle time to enter buds, eed, and

damage lea tissue. But i weatherconditions stall bud development,thrips can destroy young leaves,causing signicant orest injury. In theearly 1990s, research on pear thrips

at the UVM Entomology ResearchLaboratory produced monitoringmethods or sugar maple lea andfower development. Subsequent treeand insect monitoring at the VMCMt. Manseld site have contributedto understanding population andmanagement strategies o this insect

in relation to sugar maple processes. In 1993 and 1995, pear thrips populations were signicant,emergence and eeding developed sooner than sugar maple lea development, and this resultedin large areas o orest injury. Normally, sugar maple lea emergence outpaces thrips eedingand little lea injury occurs.

Additional monitoring o other hardwood species has increased our understanding o theprogression o spring development among species, at dierent elevations and within orestcanopies. Managing orest health in Vermont requires answering questions about the timingo tree species development. For example, when VMC researchers received a request orinormation on the timing o sugar maple pollination, the answer was readily available: between

April 28th and May 15th. Another request or inormation came rom the maple syrup industry,

Figure 20: StandardizedPrecipitation Index (SPI)

or the western climate

division o Vermont

1895-2008. Periods o

excessive precipitation

and droughts have beennoted.

Source: Courtesy the National

Drought Mitigation Center

4

3

2

1

0

-1

-2

-3

-4

Standardized Precipitation Index 1895-2008

SPI

values

1895

1899

1903

1907

1911

1915

1919

1923

1927

1931

1935

1939

1943

1947

1951

1955

1963

1967

1971

1975

1979

1983

1987

1991

1995

1999

2003

2007

Months

1927 1938

1955

1998,19992005

199519871980

197819631915

Table 4:Floweringdates o understory

spring plants at

Proctor Maple

Research Center in

Underhill. Data results

are rom 18 years o

monitoring (1991-

2008).

Source: Sandy Wilmot andTom Simmons, VTFPR


26/44

24

which was interested in expanding tapping to include red maple trees and needed inormation

on the timing o red maple bud development in comparison to sugar maple. Red maple hasbeen traditionally thought o as fowering early in spring and so could potentially add a buddyfavor i mixed with sugar maple sap. Although red maple fower buds begin to swell onaverage two days earlier than sugar maples, budbreak (when leaves start to emerge) is actuallylater. Sugar maple bud development is on average 37 days rom bud swell to ull lea out,

whereas red maple is 51 days. Monitoring results indicated that red maple, on average, leaedout 14 days later that sugar maple, so timing o lea out was not a valid reason or excludingred maple sap.

Spring development, however, is highly variablerom year to year and location to location, dependingon temperature, precipitation, snow pack, and otherenvironmental actors. On Mount Manseld with itscolder temperatures, increased snow pack, and otherenvironmental dierences, lea development o sugar

maple orests located at 2,200 eet was 7-10 days laterthan at 1,400 eet.

Because o interest in climate change, researchersare oten asked i the timing o lea development isearlier or later than normal. Sugar maple budbreak(green tip o lea emerging rom buds) and lea out(ull lea development) have been earlier in the decadeo the 2000s compared to the 1990s. While there is

much variability rom year to year, eight o the nineyears o earlier than normal lea development occurred since 2000. On average, budbreak isthree days earlier and lea out is ve days earlier this decade than in the 1990s (Figure 21). In

2008, monitoring show

2009 report: how air quality affects vermont forests

Documents