bringing trees back in the philippines

7/28/2019 Bringing Trees Back in the Philippines

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AUSTRALIAN CENTRE FOR INTERNATIONAL AGRICULTURAL RESEARCH R E S E A R C H N O T E S

Partner in Research for Development RN 24 12/00

Reforestation is

recognised as an urgent need in the Philippines following the clearing of most of the native forest cover. Large- scale tree plantingefforts have, however,

been much less successful than hoped. Research has identified the reasons for this disappointing outcome, and provided the basis for successful treeestablishment even on

severely degraded sites.

A U S T R A L I A N C E N T R E F O R I N T E R N AT I O N A L A G R I C U LT U R A L R E S E A R C H

Bringing trees back in the Philippines

ACIAR Research Notessummarise results andbenefits from selectedACIAR projects, withthe aim of ensuring thewidest possibleapplication. We inviteextension and researchdepartments to reprint ortranslate either the wholedocument or any part

considered useful.

Reforestation is

recognised as an urgent need in the Philippines following the clearing of most of the native forest cover. Large- scale tree plantingefforts have, however,

been much less successful than hoped. Research has identified the reasons for this disappointing outcome, and provided the basis for successful treeestablishment even on

severely degraded sites.

Seventy years ago 60% of the Philippines was covered with forest, today it is less than

20%. As part of efforts to restore some of the tree cover ACIAR research is providingthe basis for successful tree establishment.


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timber; while culling of old, lessproductive trees can be beneficial, toomuch harvesting will reduce the outputof copra and coconut oil, the Philippinesmost valuable export commodities.

Much of the clearing has occurred in theuplands as a result of pressure from arapidly growing population needing landboth for farming and wood. Severeerosion over very large areas of slopingcountry has diminished the productivecapacity of the soil and producedconditions favouring Imperata cylindricagrass, known in the Philippines as cogon.To maximise the nutritive value of thisvery poor cattle feed, or to make it easierto establish crops, the farmers burn thegrass each dry season. The fire producesfresh shoots, but often also damages the

remaining forest.

The problem

Seventy years ago around 60% of the landarea of the Philippines was covered withforest today the figure is less than 20%.Most of the clearing has occurred sinceWorld War II, with vast areas of forestland harvested for the timber revenue

and subsequently cleared for agriculture.The process was unsustainable andenvironmentally damaging, and nowlumber exports are banned andreforestation has become a governmentpriority. The proportion of the countrysGross National Product attributed toforestry and timber products has fallenfrom 12.5% in 1970 to about 1% today.

One result of the clearing is a nationalshortage of wood, which has madesubstantial timber imports necessary.Of considerable concern is a growingreliance on coconut trees for construction

The proportion of the countrys Gross National Product attributed to forestry and timber products has fallen from 12.5% in 1970 to about 1% today.


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Through the active involvement of anetwork of collaborators, the project wasable to cover most of the major timberproducing regions of the Philippines. Thecollaborators who kept in touch viaplanning and review meetings, site visitsand exchange of information through anewsletter included a broad range of

research groups, industrial plantationcompanies and community groups.

Tree selection

A key goal was to improve the matchingof tree species, and provenances withinspecies, to site characteristics principally soil and climate. To this end,the researchers evaluated trees and shrubswith a variety of end uses in trials at 12locations (see map). As fuelwood is byfar the largest use category in thePhilippines, exceeding the woodrequirement for all other purposes by afactor of about ten, emphasis was placedon fast-growing species that should thrivein farm woodlots as well as industrialplantations. Several of these species canalso provide high value timber forsawlogs, veneers, plywood and furniture.

Preferred plantation species in thePhilippines have been the fast-growingnative eucalypt bagras ( Eucalyptusdeglupta ); two trees originally fromSouth America, gmelina ( Gmelinaarborea ) and mahogany ( Swieteniamacrophylla ); and teak ( Tectona grandis )from Burma and India. As well as these,the project trials included fast-growingeucalypts, acacias, casuarinas andgrevilleas from Australia (and in the caseof one of the most promising eucalypts,

E. urophylla , Timor). Many are potential

producers of timber and pulp as well asfuelwood. A key advantage of some of the Australian species is their ability togrow in soils with low fertility; while thenative and naturalised species generallywill not establish, grow or thrive indegraded soils dominated by cogon grass,some of the Australian species haveshown a strong capacity to do so. Also,importantly, many are tolerant of fire, thecause of more than 70% of plantation treelosses in the Philippines.

Major reforestation efforts by governmentorganisations, private companies andfarmers many of them funded by loansfrom international agencies have beenfar from universally successful. A reviewpublished in 1994 found that only about42% of the total area planted had becomesuccessful, productive plantations.Research supported by ACIARinvestigated the reasons for thisdisappointing outcome and has helped

provide the basis for much better resultsin the future.

Australian species can tolerate fires. Above a fire in aPhilippines trial of Australian eucalypts in April 1998,below the same forest has recovered in October 1998.

Major reforestationefforts by government

organisations, private companies and farmers many of them funded by loans from international agencies have been far from universally successful.


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Cebu trials (poor sites)

Leyte trials (good sites)

The performance of trees in trials at twopoor sites (Juanay and Tigbawan, Cebu)and two relatively fertile sites (Matalomand Ormoc, Leyte) illustrates the growthpotential of various species. Average treeheights at ages up to 3 years are shown inthe graphs.

The project site (top) at Matalom on the Island of Leytewas a disused paddock unable to support crops. Theother two photos (below) show the site three years afterplanting species and provences from Australia andPapua New Guineasome trees had reached 15 m.

Age of the stand (years)

A. crassicarpaE. camaldulensis

E. urophylla S. saman

H e i g h t o

f t h e s t a n

d ( m )

0.5 1 1.5 2 2.5 3 3.5

10

8

6

4

2

0

H e i g h

t o

f t h e s t a n

d ( m )

Age of the stand (years)

A. crassicarpaE. camaldulensisE. urophylla

A. mangium

E. deglupta

L. leucocephala

P. indicus S. macrophylla

0.5 1 1.5 2 2.5 3 3.5

10

8

6

4

2

0

12

14

16

Fast-growing species

and provenances from Australia and Papua New Guinea adapted to a wide range of environmentsincluding degraded

grassland sites.


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Fast growing trees planted at 1000 stems

per hectare require thinning after 3 years,so that the best trees can grow on to theirpotential and produce higher valueproducts such as sawlogs. The ACIARtrials indicated that 3 year old thinningsfrom plantings of some Australian speciescan provide valuable light constructiontimber as well as fuelwood.

Growing the trees

In addition to choice of the best speciesfor a site, successful plantationestablishment depends on use of highquality genetic stock, good nurserypractice, effective land preparationincluding weed control, appropriatefertilisation and good silviculturalpractices. Other factors that need to betaken into account in the Philippinesinclude the likelihood of fire damage andof typhoons, which strike on averageevery three to four years in the northern

and central parts of the country.To date, most of the seedlings sown byfarmers have come from poor, inbredgenetic stock. Attempts to collect, storeand germinate seed of superior individualtrees have had little success. However,clonal propagation has been developed byplantation companies in the Philippinesand used for large-scale plantings of gmelina and eucalypt hybrids. Thistechnology offers the opportunity to

multiply superior timber trees for use inplantations and on farms.

Among the fastest growing trees werethe Australian species Acacia mangium ,

A. crassicarpa and Eucalyptuscamaldulensis , and E. urophylla fromTimor. The height growth of thesegenerally surpassed that of the native

E. deglupta (bagras) and Pterocarpusindicus (nara) and the naturalised Albizzia(Samanea) saman (acacia or rain tree),

Leucaena leucocephala , and Swieteniamacrophylla (mahogany). And the growthwas not only upwards; at 3 years of agethe average diameter at breast height of the Australian species on the Leyte siteswas double that of the native andnaturalised species.

These two photos demonstrate the difference inperformance between (above) well nodulated Acaciaaulacocarpa and (below) a non-nodulated provenance.

Other factors that need to be taken into account in the Philippinesinclude thelikelihood of fire

damage and of typhoons.

Other factors that need to be taken into account in the Philippinesinclude thelikelihood of fire

damage and of typhoons.


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An outcome of the ACIAR research thatwill help improve the quality of the treeseedlings offered for planting is newpotting mixes made from inexpensive,locally available materials. Otherdevelopments at the nursery stage includeways to better train roots and to harden off and grade plants. Requirements for

nutrient additions in nurseries have beendetermined, and procedures for large-scale inoculation of acacias with nitrogen-fixing Rhizobium bacteria established.

The ability of acacias to form Rhizobium -containing nodules on their roots and fixnitrogen is important both for their owngrowth and for improvement of the soil.The contrasting performance in trials onMindanao of very well nodulated acaciasand others without nodules (pictured on

page 5) illustrates the impact nitrogenfixation can have; the nodulated trees grewabout twice as fast as the others. Initiallythese tree were regarded as two differentprovenances of Acacia aulacocarpa , butfollowing a taxonomic revision they nowbelong to separate species A. peregrinaand A. disparrima . More work needs to bedone on the matching of Rhizobium strainswith their acacia hosts. Strains isolatedfrom Australian and Papua New Guineaacacias in their natural habitats havegenerally proved much more effective thanthose naturally present at planting sites inthe Philippines and other countries.

Researchers also investigated prospectsfor boosting the growth of eucalypts byinoculating seedlings with mycorrhiza fungi that help plants take up nutrientsfrom the soil in the nursery. The soilunder land cleared of trees many yearspreviously is generally deficient inmycorrhiza, so inoculated plants should

have a considerable advantage there.Again, a key consideration is matchingtrees with an appropriate inoculum strain.Considerable success was achieved in thegreenhouse in producing seedlings withmycorrhizal roots, but production of inoculants for commercial use has so farproved problematic and lasting benefitsfrom inoculation remain to bedemonstrated in the Philippines.

The research confirmed the critical

importance to tree establishment of effective weed control. Weeds need to be

cleared to a radius of one metre aroundeach planting hole, and controlled for atleast 6 months after planting. Holesshould be dug well in advance of

planting, with dimensions of at least30 30 30 cm in stony and infertilesoils and 20 20 20 cm on better land.Fertiliser should be applied in a ringaround each tree at planting and 3 to 6months later.

Tree nutrition

The project developed two approaches todetermining fertiliser requirements for

successful plantation growth identifying nutrient deficiencies in thesoil and assessing the nutrient status of trees. The soil method, refined byresearchers from the Visayas StateCollege of Agriculture (ViSCA), involvesmonitoring the growth of indicatorplants in pot trials. The pots contain soilfrom the test site with all essentialnutrients except one a differentnutrient for each pot added. Variationsin growth between the pots show whichnutrients are deficient in the soil or if there are toxicities.

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Mrs Madeline Dios, a farmer from Bukidnon,Mindanao, has learnt the advantages of nitrogen-fixingtrees. Here she holds roots of her Acacia mangium treesto display the nitrogen-fixing nodules.

The research confirmed the critical importance to tree establishment of effective weed control.


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The technique revealed deficiencies atmost of the trial sites, and showed thesewere severe at some sites. The findingsprovided the starting point for fertiliserrate trials to quantify nutrient additionrequirements. Researchers performedtests with various forms of fertiliser,including organic types.

Analysis of the concentrations of nutrientelements in leaves provided the startingpoint for developing ways to identifydeficiencies in growing trees. Leaf sources were trees from sites with knowndeficiencies and from other sites with anapparently adequate nutrient supply. Alsoincluded were trees displaying obvioussymptoms of inadequate nutrient uptake notably the yellow mangiumsyndrome in Acacia mangium . This

condition was found to have a wide rangeof possible causes nitrogen,phosphorus, potassium, iron, manganese,sulphur and boron deficiencies or anexcess of nickel or chromium.

The data bank built up covering morethan 1000 leaf samples from 28 species isa valuable resource, defining deficientand adequate concentration ranges for thedifferent nutrients. It revealed, forexample, severe potassium deficiency ineucalypts and acacias at sites inMindanao and Cebu. Adding potassiumfertiliser had a rapid positive impact onboth the leaf symptoms and plant growth.

In related work, researchers grew acaciasand eucalypts in solutions providingnitrogen, phosphorus and potassium at sixconcentration levels and calcium, sulphur,magnesium, iron and boron at threelevels. They photographed and wrotedescriptions of the deficiency symptomsthat developed, and chemically analysedleaves so that nutrient content readingscould be matched to the symptoms. Thephotographs and findings will provide thebasis for a field guide that growers willbe able to use to assess the nutrient statusof their trees.

Spreading the wordThe primary focus of the research waslarge-scale industrial plantations, but ithas had valuable spin-offs for farmersinterested in growing trees. Experienceshows that communities adopt new treegrowing technologies quickly oncefarmers have seen how effective they

can be, and in the Philippines sixcommunities are now applying findingsfrom the project. They have establishednurseries and field plantings to evaluatethe best species and provenances for theirfarmers to grow.

Findings are being applied in the plantingand management of communal areas aswell as farms. In one example of sustainable community-based forestmanagement, the 106-member Agro-

forestry Development MultipurposeCooperative at Alcoy, Cebu, maintains911 hectares of reforested land in an areaof poor soils. The farmers grow cash

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Nutrient deficiency trials at Queensland University wereable to reproduce the yellow mangium syndrome in

Acacia mangium by omitting essential nutrientsin thiscase potassium.

Experience shows that communities adopt new tree growing technologiesquickly once

farmers have

seen howeffective they

can be.


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crops such as corn, carrots, onions, beansand cabbage, but come together once aweek to undertake community forestryactivities. In conjunction with the ACIARproject selected tree species have beenplanted over 4 hectares on four farms totest their suitability for these soils, whichcomprise a shallow layer of topsoil overlimestone. At another cooperative, atParaclete in Leyte, the farmers planted

120 hectares with species selected fromthe ACIAR trials in the first year afterestablishing their nursery a trulyremarkable performance.

A key outcome of the research has beenthe successful introduction of Australiantree species across a range of sites in thePhilippines. As in the examples notedearlier from Cebu and Leyte, earlyobservations indicate that many are doingsubstantially better than the species

normally planted; some trees reached aheight of 15 metres, with good stemform, only 3 years after planting. Thesuccess of the trials has encouraged theestablishment of seed orchards and seedstands of the most promising Australianspecies, to provide growers with highquality seed. In addition, some non-government organisations have decided toadopt Australian plantation species.Planning is under way for a pilotdevelopment phase that will be a majorstep towards widespread implementationof the research outcomes.

Six communities in the Philippines are now applyingthe project findings. Here Mrs Dilinila from Bukidnonin Mindanao is pictured with seedlings of Eucalyptus

robusta produced from seed in her nursery.

This Research Note is based primarily on work conducted between 1993 and 2000 in twoACIAR projects. The first, Tree establishmenttechnologies in the Philippines(FST/1992/008), involved The University of Queensland; Queensland Forest ResearchInstitute; Department of Forest BiologicalSciences, University of the Philippines at LosBaos; Department of Environment and Natural

Resources, Philippines; Ecosystems Researchand Development Services, Philippines;Bukidnon Forests Inc; C. Alcantara and SonsInc; and Visayas State College of Agriculture.Partners in the second project, Tree productiontechnologies for the Philippines and tropicalAustralia (FST/1996/110), included in additionPhilippine Council for Agriculture, Forestry andNatural Resources Research and Development;Provident Tree Farms; Paper IndustriesCorporation of the Philippines; and AquaIndustries Inc. In both cases, the Australianproject leaders were Dr Peter Dart of the School

of Land and Food Sciences, The University of Queensland, and Dr John Simpson of theQueensland Forest Research Institute.

Philippine leaders of one or both projects wereDr Angela Almendras, Visayas State College of Agriculture, Dr Elvero Eusebio, EcosystemsResearch and Development Services, Dr CesarQutierrez, Bukidnon Forests Inc, Dr DiscoraMelana, Department of Environment andNatural Resources, Dr Reynaldo De La Cruz,Department of Forest Biological Sciences, DrEdilberto Nasayao, Department of Environmentand Natural Resources, Dr Juliana LibuitBaggayan, Department of Environment andNatural Resources and Dr Segundino Foronda,Philippine Council for Agriculture, Forestry andNatural Resources Research.

Further information on these projects and otherACIAR projects is available from:

Communications UnitACIARGPO Box 1571Canberra ACT 2601Australia

e-mail: [email protected]

web address: www.aciar.gov.au

Writing Bob Lehane, Science CommunicationServices in consultation with Dr Peter Dart,University of Queensland.

Design: Design ONE Solutions

The Australian Centre for InternationalAgricultural Research (ACIAR) helps developingcountries solve their agricultural problems and

build up their research capabilities bycommissioning research partnerships betweenAustralian and developing-country researchinstitutions.

bringing trees back in the philippines

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