canopy research in the twenty-first century: a review of arboreal ecology

8/9/2019 Canopy research in the twenty-first century: a review of Arboreal Ecology

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Tropical Ecology 50(1): 125-136, 2009 ISSN 0564-3295 International Society for Tropical Ecologywww.tropecol.com

Canopy research in the twenty-first century: a review of ArborealEcology

MARGARET D. LOWMAN

Professor of Biology and Environmental Studies, Director of Environmental Initiatives,

New College of Florida, Sarasota FL, USA

Abstract:After thirty years of development,canopy science is still an emerging frontier ofexploration promising not only adventure and scientific discovery but also solutions to globalchallenges. Important environmental issues such as climate change, biodiversity conservation,and whole forest interactions have inspired data collection within canopies as well as aboveand below canopies, and catalyzing large-scale ecological monitoring. But perhaps mostimportantly, canopy ecology may herald a new set of metrics in scientific achievement for thenext generation of ecologists. As canopy science matures, the treetops have become scientific,economic, and social drivers for outreach in education and conservation. Rather than relying ontechnical scientific publications and data sets as the only measures for promotion and tenure,the next generation of ecologists increasingly prioritizes education outreach and appliedconservation as additional metrics for success as a scientific professional. The integration ofresearch, education outreach and conservation as the new tool kit for young ecologists may leadto better stewardship of ecosystems.

Resumen: Despus de 30 aos de desarrollo, la ciencia del dosel sigue siendo una fronteraemergente de exploracin que promete no solamente aventura y descubrimiento cientfico, sino

tambin soluciones a los retos globales. Temas ambientales importantes como el cambioclimtico, la conservacin de la biodiversidad, y la interacciones a nivel del bosque completohan inspirado la obtencin de datos en los doseles, as como debajo y arriba de ellos, y hancatalizado el monitoreo ecolgico de gran escala. Pero quiz ms importante an, la ecologa deldosel podra anunciar un nuevo conjunto de medidas de los logros cientficos para la siguientegeneracin de eclogos. Conforme madura la ciencia del dosel, las partes altas de los rboles sehan convertido en directrices cientficas, econmicas y sociales para el mbito educativo y laconservacin. En lugar de confiar en las publicaciones cientficas tcnicas y en los conjuntos dedatos como nicas medidas para la promocin y la definitividad laboral, la siguiente generacinde eclogos est dando cada vez ms una mayor prioridad al rea educativa y a la conservacinaplicada como indicadores adicionales del xito del profesionista cientfico. La integracin de lainvestigacin, la educacin y la conservacin son el nuevo juego de herramientas para loseclogos jvenes que puede conducir a una mejor administracin de los ecosistemas.

Resumo: Depois de trinta anos de desenvolvimento, a cincia sobre o copado ainda umafronteira emergente de explorao promissora, no s de aventura e descoberta cientfica, mastambm, de solues para os desafios globais. Uma questo ambiental importante tal como amudana climtica, a conservao da biodiversidade, e as completas interaces florestais tminspirado a recolha de dados no seio do copado bem como acima e abaixo do mesmo, bem comocatalisado uma monitorizao ecolgica em grande escala. Mas, talvez mais importante, aecologia do copado pode encabear um novo conjunto de mtricas de alcance cientfico para a

*Corresponding Author; Vice President for Education, Ecological Society of America, www.canopymeg.com


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126 CANOPY RESEARCH IN THE TROPICS

prxima gerao de ecologistas. medida que a cincia sobre os copados amadurece, os cimosdas copas das rvores podem tornar-se os motores cientficos, econmicos e sociais para aextenso na educao e conservao. Em vez de depender das publicaes tcnico-cientficas econjuntos de dados como a medida nica para a promoo e status permanente, a nova gerao

de ecologistas d primazia, de forma crescente, extenso da educao e conservao aplicadacomo uma mtrica adicional para o sucesso como profissional cientfico. A integrao dainvestigao, da extenso da educao e conservao como uma nova ferramenta para os jovensecologistas pode conduzir a uma melhor guarda dos ecossistemas.

Key words:Canopy research, ecology education, global canopy program, tropical rainforests.

Introduction

History of methodology to study forest canopies

Forest canopies have long eluded scientificresearch because of the logistical difficulties ofreaching tree crowns and the subsequentchallenges of sampling for researchers whomanage to ascend above the forest floor (Lowman2004a; Moffett & Lowman 1995). Original methodsincluding slingshots, ropes, and simple hardware(Fig. 1) have advanced to include networks ofcranes, towers and walkways that facilitate morerigorous experimental testing of hypotheses aboutcanopy processes (Fig. 2). Only in the last two

decades have scientists undertaken extensiveexploration of this complex world of plants, insects,birds, mammals, and their interactions. Biologistsin the nineteenth century traditionally based theirideas about forests on observations made atground level. These forest floor-based perceptionsare summarized in a comment by Alfred R.Wallace (1878):

Overhead, at a height, perhaps, of a hundred

feet, is an almost unbroken canopy of foliage

formed by the meeting together of these great trees

and their interlacing branches; and this canopy is

usually so dense that but an indistinct glimmer of

the sky is to be seen, and even the intense tropicalsunlight only penetrates to the ground subdued and

broken up into scattered fragments it is a world

in which man seems an intruder, and where he

feels overwhelmed.

Ideas about forest canopies changed very littlefor almost one hundred years until biologistsbegan applying technical climbing hardware to

trees in the 1970s. This creative approach wasundertaken independently at two locations aroundthe world, at a time before the invention ofinternet, so the researchers were unaware of theircommon methodology. Don Perry (1986) adaptedtechnical climbing hardware to ascend a Ceibapentandra (kapok tree) at La Selva BiologicalStation in Costa Rica, while Lowman stumbledupon caving hardware as a means to explore leaflongevity in emergent trees of the Australian rainforests (Lowman 1985, 1999). At this time,communication of methods and findings fromremote tropical jungles on the opposite sides of theglobe was slow, and only via snail mail. Canopyaccess using ropes, although independentlyevolved across the globe, eventually appeared side-by-side in the journal Biotropica, when Perryscolleague published her Costa Rica work in thesame issue as Lowmans first Australian data set(Lowman 1984; Nadkarni 1984). As two post-doctoral canopy women whose careers invariablyshared commonality halfway around the world,subsequent communication has since led to manycollaborative canopy programs.

The 1970s and early 1980s represented the eraof single rope techniques (SRT). This portable,relatively inexpensive method of canopy studyallowed canopy access even to graduate studentswith their modest budgets. Ropes and harnesseswere not effective, however, to reach the leafyperimeters of tree crowns, since ropes wererestricted to positions looped over sturdy branchesclose to the tree trunk; and SRT was not useful foremergent trees whose enormous canopies usuallyextended far away from the main trunk itself. Toaccess foliage on the extremities, Peter Ashton and


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colleagues invented the canopy boom, a horizontalbar with a bosuns chair at one end, that swunginto the leafy canopy away from the main trunk(Appanah & Chan 1981). Scaffolds were trialed ineucalypt forests of Australia; and cherry pickerswere also used to access the outer and upper

perimeters of tree canopies for studies of eucalyptdieback (Lowman & Heatwole 1992).

In 1992, Alan Smith of Smithsonian TropicalResearch Institute (STRI) set up the firstconstruction crane to study forest canopies inPanama (Parker et al. 1992). Although relatively

Fig. 1. Single rope techniques provide canopy access to a Ceiba pentandratree alongthe Amazon River, Peru.


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expensive, this device allowed access to any regionof canopy beneath the crane arm without regard tothe tree trunk. Specific protocols such asmeasuring herbivory (Shaw et al. 2006), carbonuptake (Korner et al. 2005), and even lizardexclusion (Dial & Roughgarden 2004), havefacilitated more rigorous experimental approachesin the canopy, especially with the advent of cranes.Under the auspices of the Global CanopyProgramme (GCP), four new whole-forestobservatories are proposed that will expand thecurrent crane network of nine to include tropicalforest sites in Brazil, India, Madagascar, andMalaysia (Mitchell et al. 2002). In partnershipwith ATREE (Ashoka Trust for Research andEcology and the Environment), Indias crane willbe cited in the Western Ghats.

Simultaneous with the launch of the cranes,French botanist Francis Hall designed a colorfulhot-air balloon and raft operation, called Radeaudes Cimes (translation: raft on the rooftop of theworld). Its inflatable raft is 27 m diameter andforms a base camp for researchers in the treetops.A dirigible, or hot air balloon, operates inconjunction with the raft, transporting researchersto new locations in the canopy to study biodiversity

and the canopy-atmosphere interface. In 1991, theFrench expedition pioneered a new techniquecalled the sled, or skimmer. This small (5 m)inflatable equilateral triangle is towed by theballoon so the scientists can trawl the uppermostcanopy for biodiversity surveys. With the sled,rapid collection of canopy leaves, flowers, vines, orepiphytes as well as their pollinators or herbivorescan be conducted offering spatial without thelimitations of temporal variability (Mitchell et al.2002; Lowman 2004a).

In recent years, canopy biologists have utilizedinnovative combinations of field tools many metersabove the forest floor. Korner et al. (2005)measured canopy response to increasedatmospheric carbon dioxide in Swiss temperateforests using a crane outfitted with portableanalyzers. At another European crane site nearLeipzig, Germany, Szarzynski & Shaw (2005)quantified canopy light with infra-redphotography, called thermal imaging (Fig. 3). Athird innovative field team uses towers, catwalks,and plastic panels above the canopy to facilitatemanipulative experiments simulating drought inAmazonian lowland tropical rain forest (Cattnioet al. 2002). Using a combination of hot-air balloon,

Fig. 2. Schematic drawing of the development of canopy biology, and of nutrient cycling from canopy to forest floor.


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inflatable raft, ropes and construction crane (Fig.4), Yves Basset of the Smithsonian TropicalResearch Institute coordinated the firstcomprehensive, collaborative survey of canopyarthropods through a vertical column ofPanamanian tropical forest (Didham & Fagan2003).

Canopy walkways have providedunprecedented access to bromeliads to surveybiodiversity and other ecological phenomena

(Burgess et al. 2002, 2003; Lowman et al. 2006).Towers combined with aerial imagery andsampling techniques have fostered a new era offorest canopy modeling, including studies ofdeforestation, gas exchange, and simulations ofatmospheric gases (e.g. Keller & Lerdau 1999).Because the forest canopy represents a directinterface between earth and atmosphere, this layerof biodiversity plays a critical role in

environmental monitoring of temperature changes,rainfall variability, eddy fluxes, pollution, andproductivity (reviewed in Laurance & Peres 2006).

The new National Ecological ObservatoryNetwork (NEON) proposes to deploy anetwork offacilities including cranes, towers, sensortechnologies, miniaturized analytical instruments,and remote cameras to document and forecastchanges in ecosystems at regional and continentalscales (Senkowsky 2005). In addition to research

alone, NEON will enhance science education andoutreach for citizens, students, and policy-makers.Canopy access, as part of the NEON toolkit, hasthe potential to inspire students and citizens withan enthusiasm for ecology as well as withsophisticated data sets.

At the fourth international canopy conferencein Leipzig, Germany, in July 2005, 42 of 87 talksreported new findings on canopy biodiversity (and

Fig. 3. Thermal imaging of the deciduous forest surrounding the Leipzig canopy crane in Germany (Photo by DavidShaw).


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29 featured arthropods). Of note, the notion ofregional knowledge transfer was introduced to

canopy science through several reports. In onecase, indigenous villagers were trained as

Fig. 4. Methods of canopy access used in the project IBISCA. From top left, clockwise: canopy crane (gondola view),canopy bubble, canopy fogging, Ikos (tree platform), single rope techniques and canopy raft (photo IBISCA archives).


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parataxonomists in New Guinea to contribute to alarger study on the effect of canopy openness oninsect herbivores (Basset et al. 2004). While theirscientific results suggested that conspecific mature

trees and seedlings/saplings supported distinctherbivore fauna (contrary to the assumptions ofthe Janzen-Connell), what might be moreimportant than their scientific findings was thefact that these researchers empowered theindigenous people to understand their extra-ordinary biodiversity. Such regional knowledgetranslates into forest conservation when localsgain a global perspective of their unique bio-diversity. Their research results indicated thattropical arthropods may be less specialized thanpreviously thought in terms of resource use, butmore specialized in terms of habitat use (Basset etal.2003). If insect-plant interactions in the tropicsare not as highly specialized as previously thought,global estimates of species richness may beoverestimated (Novotny et al. 2002). Their studiesalso serve as an important conservation example ofregional knowledge transfer (www.antu.cas.cz/png/index.html).

Forest ecosystems are threatened globally byfragmentation and deforestation (Laurance & Peres2006). The integrity of forest canopies is critical tomaintaining regional and global productivity andclimate conditions. Continued efforts to identify andmap biodiversity in forest canopies, to quantify

canopy-atmosphere and canopy-soil fluxes, and toeducate the public about both economic andecological aspects of forest conservation are criticalas global pressures on ecosystem health intensify(Bawa et al. 2004). In the Western Ghats, canopybiologists study pollination of emergent trees andalso the ecology of interactions between the canopytree Cullenia exarillata seeds and primatesincluding the lion-tailed macaques, Macaca silenus(Ganesh & Davidar 1999). The advent of a canopycrane in India will generate greater media attentionleading to public education about the ecosystemservices provided by Indias few remaining tracts of

tropical forest.Such progression from data sets to

conservation solutions represent important nextsteps for canopy science, but will require scientiststo communicate their information more effectivelyto the public sector (Lowman 2006). The nextcanopy conference, to be held in Bangalore, India,in 2009, will feature dedicated sessions on canopy

education and outreach, climate change, andglobal forest conservation (www.canopy2009.org).In summary, canopy science is maturing beyond amethods-based, conventional-reporting focus to

embrace cutting-edge global science questionsusing a sophisticated array of methods. Thistrajectory will have consequences not only forresearch, but also for education outreach andconservation.

Case studies where canopy research

fosters conservation and ecology

education through regional

knowledge transfer

Our ancestors were tree dwellers. Throughout

human history, people have taken to the trees assafe havens, sites of special spiritual connection,and as a cornucopia for food, medicines, materials,and productivity. In an evolutionary sense,humans descended from ancestors in the treetops.In Papua New Guinea, a tribe called the Korowaistill lives in the treetops, erecting aerial housesaccessible only by twig ladders. It is speculatedthat their unusual habit of community tree housesevolved as a mechanism to escape enemies on theforest floor, and provide a healthy environmentabove the dank, dark understory. Tree housesremain a recreational vestige of children and

adults alike that inspire links between humansand the natural world.Why do the treetops hold such a spiritual, as

well as scientific importance for culturesthroughout the world? And why have scientistsoverlooked canopy exploration in scientificdiscovery? Relatively few unknown frontiers ofexploration remain in the 21st century, but thetreetops are still considered a black box inscience. Innovative partnerships betweenbusinesses, educators, and scientists linked by acommon denominator of the treetops are emergingthat positively impact science education,

environmental justice, and local economiesthrough efforts such as ecotourism.

(a) Fostering ecology education through

canopy science

The Jason Expedition (www.jason.org), adistance learning program, annually engages over 3million middle school students and teachers


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worldwide on remote field expeditions using satellitetechnology. In 1994, 1999, and 2004, the JasonProject featured canopy research, including thechallenges of access and data collection in the

treetops. During 2004, Jason XV studied the linksbetween the brown (i.e. forest floor) and the green(i.e. canopy) food webs in the forest canopy of BarroColorado Island, Panama (Lowman et al. 2006).Science curricula developed specifically for thecanopies of Panama fostered student learning aboutthe complex linkages among biodiversity,biogeochemical cycling, and global environmentalconditions. Researchers conducted canopy studiesthat were broadcast live into classrooms throughoutthe world, providing a unique model that integratesresearch with ecology education. Middle schoolstudents even participated in data collection that led

to scientific publications (e.g. Burgess et al.2003).

(b) Promoting economic benefits from canopy

access tools

Canopy research has also created localeconomic incentives for conservation of foreststhrough ecotourism. With gadgets ranging fromaerial trams to zip lines to canopy platformsconnected by swaying bridges, canopy access toolsprovide recreational activities whereby the publiccan personally experience the treetops. While thismay have slightly negative consequences to some

wildlife, ecotourism does more good than harm byeducating a new generation about the canopy(Lowman 2004b). Currently, over twenty-fivecanopy walkways exist worldwide, with missions ofresearch and/or conservation education (Table 1).

Table 1. Continued.

Some Sites with Canopy / WalkwaysLamington National Park AustraliaWalpole Tree Top Walk AustraliaTahune Airwalk AustraliaMt. Equestrian Trails Lodge BelizeEcoparque de Una BrazilUlu Temburong Walkway BruneiVancouver Island Walkway CanadaHalliburton Forest Walk CanadaXishuangbahnna TropicalBotanical Gardens

China

Caparu Station Walkway ColombiaPaeque Nacional Natural ColombiaSelvatura Park Costa RicaDrake Bay Walkway Costa RicaTirimbina Rainforest Center Costa Rica

Choco Canopy Walkway EcuadorJatun Sacha Canopy Walkway EcuadorTiputini Biodiversity Station EcuadorNourages Field Station French GuyanaTree Trek Waldkletterpfad GermanyNational Park Hainich GermanyBioshere Houe GermanyKakum Forest Reserve GhanaIwokrama Walkway GuyanaBatuampar Walkway IndonesiaLambir Hills Walkway MalaysiaGunung Haliman Walkway MalaysiaTaman Negra Walkway MalaysiaMalaysian Walkway Malaysia

Poring Hot Spring Canopy Walk MalaysiaOtari-Wilton's Bush New ZealandACTS Canopy Walkway PeruCanopy Inkaterra PeruAmazonia Expeditions PeruMomon River Lodge PeruHSBC TreeTop Walk SingaporeTsitsikamma Forest South AfricaSri Lanka Arial Walkway Sri LankaLuguillo Exp. Forest (PR) USACoweeta Hydrologic (NC) USAEcotarium (MA) USAHampshire College (MA) USAHopkins Memorial Forest (MA) USA

Marie Selby Bot. Gardens (FL) USAMillbrook School (NY) USAMyakka River State Park (FL) USAOxbow Meadows (GA) USASoutheast Exp. Rainforest (AK) USACypress Valley (TX) USAUniversity of the South (TN) USAFalealupo Walkway Western SamoaBorneo Canopy Crane Malaysia

Table 1. Current list of walkways and cranesthat offer research and education programs, ascollated at the Fourth International CanopyConference (to submit additional sites, pleasecontact: www.canopymeg.com).

Some Sites with Canopy / CranesAustralian Canopy Crane Australia

Leipzig Canopy Crane GermanyKranzberg Canopy Crane GermanySollIing Research Crane GermanyTomakomai Crane JapanPanama City Crane PanamaSan Lorenzo Crane PanamaBasel Canopy Crane SwitzerlandWind River Crane USASurumoni Crane Venezuela

Contd


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In Western Samoa, a canopy walkway was builtto pay off a debt incurred to build a local school. Ledby ethnobotanist Paul Cox, a team of Americancanopy builders (www.treefoundation. org) met withthe fifteen village chiefs to discuss the risks of thisecotourism venture. After drinking copious amountsof kava, a local drink, the chiefs unanimouslyapproved the construction of a walkway into anemergent Ficus tree. Profits from this successfulventure paid for school construction without themore conventional solution of logging local forests(Lowman et al.2006). The chiefs wisely recognizedthat logging would ultimately destroy their islandecosystems, and that ecotourism provided a moresustainable income stream.

Ecologists face increasing challenges tointegrate sociological considerations with scientificresearch, and again, canopy biology can offer some

innovative case studies. To conserve epiphyticmosses that are over-collected by zealous orchidgrowers as a potting substrate, Nalini Nadkarniengaged prisoners to cultivate threatened mossesof the Pacific Northwest forests (Fischer 2005). Atpresent, growth rates of mosses are too slow forcommercial production, but horticultural therapyoffered both emotional and economic benefits forthe inmates, as well as epiphyte conservation. Inanother example, Lowman engaged localcommunities to own real estate in the treetopsand subsequently support the construction oftreetop walks (Lowman et al. 2006). Visitors towalkways in Queensland, Australia and Sarasota,Florida, are encouraged to purchase a plank,which funds the maintenance of the walkway aswell as a sense of ownership to heighten localforest conservation (www.treefoundation.org).

Fig. 5. The author teaches middle school children about canopy-forest floor interactions during the Jason Project, adistance learning broadcast that uses forest canopies as an effective driver for science education.


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(c) Forest canopies as mediators of global

environmental change

Canopy cover represents a key driver in social,

economic and biological assessments of globalchange (e.g. Lamb et al. 2005). The growingnumber of options for safe, replicated canopyresearch has facilitated expanded studies of forestprocesses. Two relatively new areas of canopyexploration nutrient cycling and decompositionfrom canopy to forest floor and back again, andexperimental studies of climate change at thecanopy-atmosphere interface illustrate theoverarching global significance of current canopyresearch.

Canopy herbivores influence nutrient cycling insect frass (feces) and defoliation directly remove

leaf material that cascades to the forest floor andultimately recycles (Fig. 2). At least sevenmechanisms have been identified by whichherbivores can influence soil nutrient dynamics(Hunter 2001) including the linkage betweencanopy defoliation and rates of nutrientcycling/export. At a watershed scale, importanteffects of canopy defoliation include changes innutrient cycling and nutrient export (Eshleman etal. 1998). At the continental scale, insectoutbreaks can wreak havoc on both the ecology ofeconomy of entire regions (e.g. Lowman &Heatwole 1992).

Through fall can change in chemicalcomposition as a result of folivory, primarilythrough increased rates of nutrient leaching fromchewed leaves and dissolution of insect frass (Frost& Hunter 1994). Soil nutrient cycles can respondrapidly to inputs of frass and modified through fallbecause these inputs do not require themineralization of complex organic matter. Simplyput, they can speed up the rate of nutrient cycling.These effects are analogous to McNaughton et al.s(1988) fast cycle or the acceleration hypothesis(Ritchie et al. 1998). In contrast, herbivore-mediated changes in the quality of leaf litter likely

influence nutrient dynamics more slowly and areanalogous to McNaughton et al.s (1988) slowcycle. In fact, depending upon the quality of litterfall, canopy herbivores might sometimes act todecelerate nutrient cycling. Both fast- and slow-cycle effects, and acceleration or deceleration ofcycles, may occur in the same system but ondifferent time scales. For example, herbivoreactivity may increase rates of nitrogen cycling and

primary production in the short-term (e.g. throughfrass inputs) while causing both to decline in thelong-term (e.g. through selection of chemically-defended plant parts that decompose slowly)

(Uriarte 2000). Such detailed analyses ofinteractions cascading through the canopy to forestfloor, and cycling back again, will facilitate bettermanagement of forest ecosystems, and also help toquantify global cycles essential to life on earth.

Both insect epidemics and humans reduce theforest canopy through defoliation anddeforestation. Loss of forest cover is linked toclimate change, and the subject of globalinvestigations (Feddema et al. 2005). Canopyremoval reduces evapotranspirative cooling,offsetting the effect of increased albedo, therebyincreasing soil surface temperatures and reducing

precipitation and relative humidity (Anhuf 2005;Foley et al.2003). They calculated a net warmingof 1-2 oC in tropical regions as a result ofdeforestation, an effect that would exacerbate thewarming due to increased atmospheric CO2.Surface warming and drying can stress and killadjacent vegetation, leading to destabilizingpositive feedback and an advancing front ofdeclining forest. Using the Swiss canopy crane,Korner et al. (2005) exposed a deciduous stand toelevated carbon dioxide, simulating potentialconditions of climate change. After only oneseason, nearly half of the emitted soil carbon

dioxide originated from new carbon, and nearly allmycorrhizal fungi biomass was comprised of newcarbon, indicating a very rapid canopy-soil linkage.Korner et al. (2005) studying the links betweendeforestation and precipitation predict thatdeforestation in Amazon region will lead to drierconditions. Reduced canopy cover and subsequentlandscape degradation in turn affects theeconomics and social structure of many regions, inaddition to the loss of ecological integrity (Lamb etal. 2005). Recent predictions abound as to theglobal consequences of tropical deforestation andclimatic shifts (reviewed in Laurance & Peres

2006).The relatively young, emerging science of

canopy ecology inspires new and innovativeresearch to solve global environmental challenges.Even more important, the charisma of treetopexploration can serve as a catalyst for ecologyeducation and effective local conservationinitiatives.


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Acknowledgement

The author thanks Drs. Mark Hunter anTimothy Schowalter for collaboration on National

Science Foundation grant DEB-9815133 thatinspired some of this dialogue. In addition,National Science Foundation Informal ScienceEducation grant Out on a Limb ForestCanopies facilitated some of the ecology educationoutreach activities. In addition, the organizers ofthe Tropical Ecology Congress in Dehra Dun, India(December 2-5, 2007) provided the venue for oursession on Biodiversity Conservation in theTropics: Issues, Concerns and Strategies thatincluded this paper.

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