Averting biodiversity collapse in tropical forest protected areas

Journal name:
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Published online
Corrected online

The rapid disruption of tropical forests probably imperils global biodiversity more than any other contemporary phenomenon1, 2, 3. With deforestation advancing quickly, protected areas are increasingly becoming final refuges for threatened species and natural ecosystem processes. However, many protected areas in the tropics are themselves vulnerable to human encroachment and other environmental stresses4, 5, 6, 7, 8, 9. As pressures mount, it is vital to know whether existing reserves can sustain their biodiversity. A critical constraint in addressing this question has been that data describing a broad array of biodiversity groups have been unavailable for a sufficiently large and representative sample of reserves. Here we present a uniquely comprehensive data set on changes over the past 20 to 30 years in 31 functional groups of species and 21 potential drivers of environmental change, for 60 protected areas stratified across the world’s major tropical regions. Our analysis reveals great variation in reserve ‘health’: about half of all reserves have been effective or performed passably, but the rest are experiencing an erosion of biodiversity that is often alarmingly widespread taxonomically and functionally. Habitat disruption, hunting and forest-product exploitation were the strongest predictors of declining reserve health. Crucially, environmental changes immediately outside reserves seemed nearly as important as those inside in determining their ecological fate, with changes inside reserves strongly mirroring those occurring around them. These findings suggest that tropical protected areas are often intimately linked ecologically to their surrounding habitats, and that a failure to stem broad-scale loss and degradation of such habitats could sharply increase the likelihood of serious biodiversity declines.

At a glance


  1. Distribution of the /`reserve-health index/' for 60 protected areas spanning the world/'s major tropical forest regions.
    Figure 1: Distribution of the ‘reserve-health index’ for 60 protected areas spanning the world’s major tropical forest regions.

    This relative index averages changes in 10 well-studied guilds of animals and plants, including disturbance-avoiding and disturbance-favouring groups, over the past 20 to 30years.

  2. Percentages of reserves that are worsening versus improving for key disturbance-sensitive guilds, contrasted between /`suffering/' and /`succeeding/' reserves (which are distinguished by having lower (<-0.25) versus higher ([ge]-0.25) values for the reserve-health index, respectively).
    Figure 2: Percentages of reserves that are worsening versus improving for key disturbance-sensitive guilds, contrasted between ‘suffering’ and ‘succeeding’ reserves (which are distinguished by having lower (<−0.25) versus higher (≥−0.25) values for the reserve-health index, respectively).

    For disturbance-favouring organisms such as exotic plants and animals, pioneer and generalist trees, lianas and vines, and human diseases, the reserve is considered to be worsening if the group increased in abundance. For any particular guild, reserves with missing or zero values (no trend) are not included.

  3. Effects of improving on-the-ground protection on a relative index of reserve health.
    Figure 3: Effects of improving on-the-ground protection on a relative index of reserve health.

    This positive relationship held across all three tropical continents (a general linear model showed that the protection term was the most effective predictor of reserve health (Akaike’s information criterion weight, 0.595; deviance explained, 11.4%), with the addition of ‘continent’ providing only a small improvement in model fit (Akaike’s information criterion weight,0.317; deviance explained,16.3%).

  4. Comparison of ecological changes inside versus outside protected areas, for selected environmental drivers.
    Figure 4: Comparison of ecological changes inside versus outside protected areas, for selected environmental drivers.

    The image is an example of the strong distinction in disturbance inside versus outside a reserve. The bars show the percentages of reserves with improving versus worsening conditions.

  5. Pearson correlations comparing the direction and strength of 21 environmental drivers inside versus outside tropical protected areas.
    Figure 5: Pearson correlations comparing the direction and strength of 21 environmental drivers inside versus outside tropical protected areas.

    NTFP, non-timber forest products.

Change history

Corrected online 12 September 2012
Axis labelling in Fig. 1 and a typo in the Fig. 2 legend were corrected.


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Author information


  1. Centre for Tropical Environmental and Sustainability Science (TESS) and School of Marine and Tropical Biology, James Cook University, Cairns, Queensland 4878, Australia.

    • William F. Laurance,
    • Sean P. Sloan,
    • Susan G. Laurance,
    • Mason Campbell,
    • David Edwards,
    • Felicity Edwards,
    • Willis Logsdon &
    • Christiane Roetgers
  2. Smithsonian Tropical Research Institute, Balboa, Ancón, Panama.

    • William F. Laurance,
    • D. Carolina Useche,
    • Julio Rendeiro,
    • Margareta Kalka &
    • S. Joseph Wright
  3. School of Earth and Environmental Sciences, University of Adelaide, Adelaide, South Australia 5005, Australia.

    • Corey J. A. Bradshaw
  4. Stirling University, Stirling FK9 4LA, UK.

    • Kate Abernethy &
    • Fiona Maisels
  5. Duke University, Durham, North Carolina 27705, USA.

    • Patricia Alvarez,
    • Nigel Pitman,
    • Thomas Struhsaker,
    • John Terborgh &
    • Connie J. Clark
  6. Universidad Nacional Autónoma de México (UNAM), Morelia, Mexico.

    • Victor Arroyo-Rodriguez,
    • Julieta Benítez-Malvido &
    • Mauricio Quesada
  7. Royal Botanic Gardens, Kew, Richmond TW9 3AB, UK.

    • Peter Ashton
  8. World Wildlife Fund (WWF), Washington DC 20037, USA.

    • Allard Blom,
    • Richard Carroll &
    • Eric Dinerstein
  9. University of Dschang, Dschang, Cameroon.

    • Kadiri S. Bobo
  10. Xishuangbanna Tropical Botanical Garden, Yunnan 666303, People’s Republic of China.

    • Charles H. Cannon,
    • Min Cao,
    • Rhett Harrison &
    • Chen Jin
  11. McGill University, Montreal H3A 2T7, Canada.

    • Colin Chapman &
    • Philippe Auzel
  12. Estación de Biologia Tropical Los Tuxtlas, Universidad Nacional Autónoma de México, Veracruz 95701, Mexico.

    • Rosamond Coates &
    • Alejandro Estrada
  13. Columbia University, New York, New York 10027, USA.

    • Marina Cords &
    • Paige West
  14. Nordic Foundation for Development and Ecology, DK-1159 Copenhagen, Denmark.

    • Finn Danielsen
  15. Bart De Dijn Environmental Consultancy, Paramaribo, Suriname.

  16. Florida International University, Miami, Florida 33199, USA.

    • Maureen A. Donnelly
  17. Philipps-Universität Marburg, Marburg 35043, Germany.

    • Nina Farwig
  18. California State University, Fullerton, California 92834, USA.

    • Peter Fashing
  19. Museum Natural d'Histoire Naturelle, 91800 Brunoy, France.

    • Pierre-Michel Forget &
    • François Feer
  20. US Geological Survey, Smithsonian Institution, Washington DC 20013, USA.

    • Mercedes Foster
  21. King Mongkut's University of Technology Thonburi, Bangkok 10150, Thailand.

    • George Gale &
    • Tommaso Savini
  22. Royal Botanic Garden, Edinburgh, Scotland EH3 5LR, UK.

    • David Harris
  23. Tshuapa-Lomami-Lualaba Project, Kinshasa, Democratic Republic of Congo.

    • John Hart
  24. Virginia Tech University, Blacksburg, Virginia 24061, USA.

    • Sarah Karpanty
  25. National Museum of Natural History, Smithsonian Institution, Washington DC 20013, USA.

    • W. John Kress &
    • Louise Emmons
  26. Ashoka Trust for Research in Ecology and the Environment (ATREE), Bangalore 560064, India.

    • Jagdish Krishnaswamy
  27. University of Twente, Enschede, Netherlands.

    • Jon Lovett
  28. Instituto Nacional de Pesquisas da Amazônia (INPA), Manaus, Amazonas 69011-970, Brazil.

    • William Magnusson &
    • Tania Sanaiotti
  29. Wildlife Conservation Society, Bronx, New York 10460, USA.

    • Fiona Maisels,
    • Hugo Rainey,
    • Stephen Blake,
    • Emma Stokes,
    • William Weber &
    • David Wilkie
  30. University of York, Heslington, York YO10 5DD, UK.

    • Andrew R. Marshall &
    • Jane Hill
  31. La Selva Biological Station, San Pedro, Costa Rica.

    • Deedra McClearn
  32. Nature Conservation Foundation, Mysore 570 002, India.

    • Divya Mudappa
  33. University of Copenhagen, Copenhagen, Denmark.

    • Martin R. Nielsen
  34. James Cook University, Townsville, Queensland 4811, Australia.

    • Richard Pearson,
    • Robert Congdon,
    • Betsy Jackes &
    • Stephen Williams
  35. Leiden University, Leiden, Netherlands.

    • Jan van der Ploeg &
    • Merlijn van Weerd
  36. Wildlife Conservation Society, Kampala, Uganda.

    • Andrew Plumptre
  37. Woods Hole Research Center, Falmouth, Massachusetts 02540, USA.

    • John Poulsen
  38. Oregon State University, Corvallis, Oregon 97331, USA.

    • Douglas Robinson &
    • Duncan Thomas
  39. Museo delle Scienze, 38122 Trento, Italy.

    • Francesco Rovero
  40. University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.

    • Frederick Scatena &
    • Daniel Janzen
  41. University of Vienna, 1030 Vienna, Austria.

    • Christian Schulze
  42. Bwindi Impenetrable National Park, Kabale, Uganda.

    • Douglas Sheil
  43. University of Kansas, Lawrence, Kansas 66045, USA.

    • Robert Timm
  44. Pontificia Universidad Javeriana, Bogotá, Colombia.

    • J. Nicolas Urbina-Cardona
  45. Wildlife Institute of India, Dehradun, India.

    • Karthikeyan Vasudevan
  46. Unidad de Parques Nacionales Naturales de Colombia, Bogotá, Colombia.

    • Juan Carlos Arias-G.
  47. Museo de Historia Natural Noel Kempff, Santa Cruz, Bolivia.

    • Luzmila Arroyo
  48. Yale University, New Haven, Connecticut 06511, USA.

    • Mark Ashton &
    • David Watts
  49. Institute of Tropical Forest Conservation, Kabale, Uganda.

    • Dennis Babaasa
  50. Budongo Conservation Field Station, Masindi, Uganda.

    • Fred Babweteera
  51. Monash University, Melbourne, Victoria 3800, Australia.

    • Patrick Baker
  52. Utrecht University, Utrecht, Netherlands.

    • Olaf Banki
  53. Finding Species, Takoma Park, Maryland 20912, USA.

    • Margot Bass
  54. University of Kent, Kent CT2 7NZ, UK.

    • Inogwabini Bila-Isia
  55. Mahidol University Salaya, Nakhon Pathom 73170, Thailand.

    • Warren Brockelman
  56. University of Puerto Rico, San Juan 00936, Puerto Rico.

    • Nicholas Brokaw
  57. University Koblenz-Landau, D-76829 Landau, Germany.

    • Carsten A. Brühl
  58. Department of National Parks, Chatuchak, Bangkok 10900, Thailand.

    • Sarayudh Bunyavejchewin
  59. Taiwan Forestry Research Institute, Tapei 10066, Taiwan.

    • Jung-Tai Chao
  60. Université Paul Sabatier, Toulouse, France.

    • Jerome Chave
  61. Wildlife Conservation Society, Bangalore 560070, India.

    • Ravi Chellam
  62. Universidad Central de Venezuela, Aragua, Venezuela.

    • José Clavijo
  63. National University of Singapore, Singapore 117543.

    • Richard Corlett,
    • Enoka Kudavidanage &
    • Navjot Sodhi
  64. Indian Institute of Science, Bangalore 560012, India.

    • H. S. Dattaraja
  65. World Wide Fund for Nature (WWF), New Delhi 110003, India.

    • Chittaranjan Dave
  66. World Wide Fund for Nature (WWF), Surrey GU7 1XR, UK.

    • Glyn Davies
  67. Instituto Chico Mendes de Conservação de Biodiversidade, Atibaia, São Paulo 12952-011, Brazil.

    • Beatriz de Mello Beisiegel
  68. O Conselho Regional de Engenhara, Arquitetura e Agronomia do Pará, Belém, Pará, Brazil.

    • Rosa de Nazaré Paes da Silva
  69. University of Texas, Austin, Texas 78712, USA.

    • Anthony Di Fiore
  70. National Museum of the Philippines, Manila, Phillipines.

    • Arvin Diesmos
  71. Stanford University, Stanford, California 94305, USA.

    • Rodolfo Dirzo
  72. State University of New York at Stony Brook, Stony Brook, New York 11794, USA.

    • Diane Doran-Sheehy
  73. University of Colorado, Boulder, Colorado 80309, USA.

    • Mitchell Eaton
  74. Wildlife Conservation Society, Kinshasa, Democratic Republic of Congo.

    • Corneille Ewango
  75. University of Calgary, Alberta T2N 1N4, Canada.

    • Linda Fedigan
  76. Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany.

    • Barbara Fruth &
    • Martin Surbeck
  77. Montclair State University, Montclair, New Jersey 07043, USA.

    • Jacalyn Giacalone Willis
  78. University of California, San Diego, California 92093, USA.

    • Uromi Goodale
  79. Field Museum of Natural History, Chicago, Illinois 60605, USA.

    • Steven Goodman
  80. Universitat de Barcelona, 08028 Barcelona, Spain.

    • Juan C. Guix
  81. Kenya Institute for Public Policy Research and Analysis, Nairobi, Kenya.

    • Paul Guthiga
  82. Missouri Botanical Garden, St. Louis, Missouri 63166, USA.

    • William Haber
  83. University of Leeds, Leeds LS2 9JT, UK.

    • Keith Hamer
  84. Wild Chimpanzee Foundation, Abidjan 23, Cote d'Ivoire.

    • Ilka Herbinger
  85. Dinghushan Biosphere Reserve, Zhaoqing, People’s Republic of China.

    • Zhongliang Huang
  86. Tunghai University, Taichung 407, Taiwan.

    • I Fang Sun
  87. Clemson University, Clemson, South Carolina 29634, USA.

    • Kalan Ickes
  88. Osaka City University, Osaka 558-8585, Japan.

    • Akira Itoh
  89. Instituto Florestal, São Paulo, São Paulo 02377-000, Brazil.

    • Natália Ivanauskas
  90. Botanical Research Institute of Texas, Fort Worth, Texas 76107, USA.

    • John Janovec &
    • Mathias Tobler
  91. South China Botanical Garden, Guangzhou 510650, People’s Republic of China.

    • Mo Jiangming &
    • Lu Xiankai
  92. Anglia Ruskin University, Cambridge CB1 1PT, UK.

    • Trevor Jones
  93. Fundación para la Conservación del Bosque Chiquitano, Bolivia.

    • Hermes Justiniano
  94. University of Ulm, 89069 Ulm, Germany.

    • Elisabeth Kalko
  95. Mbarara University of Science and Technology, Mbarara, Uganda.

    • Aventino Kasangaki
  96. Conservation International, Arlington, Virginia 22202, USA.

    • Timothy Killeen
  97. Society of Subtropical Ecology, Taipei, Taiwan.

    • Hen-biau King
  98. Royal Haskoning, Water and Ecology Group, Groningen, Netherlands.

    • Erik Klop
  99. Boston University, Boston, Massachusetts 02215, USA.

    • Cheryl Knott
  100. Centre Suisse de Recherches Scientifiques en Côte d'Ivoire, Abidjan, Côte d'Ivoire.

    • Inza Koné
  101. Universidade Estadual de Londrina, Londrina, Paraná, Brazil.

    • José Lahoz da Silva Ribeiro
  102. Universidad Central de Venezuela, Caracas, Venezuela.

    • John Lattke
  103. The Bat Jungle, Monteverde, Costa Rica.

    • Richard Laval
  104. University of Alabama, Huntsville, Alabama 35899, USA.

    • Robert Lawton
  105. Boîte Postale 7847, Libreville, Gabon.

    • Miguel Leal
  106. 95 Warren Road, Framingham, Massachusetts 01702, USA.

    • Mark Leighton
  107. Colección Ornitológica Phelps, Caracas, Venezuela.

    • Miguel Lentino
  108. Parque Estadual Horto Florestal, São Paulo, São Paulo 02377-000, Brazil.

    • Cristiane Leonel
  109. Royal Society for the Protection of Birds, Sandy SG19 2DL, UK.

    • Jeremy Lindsell
  110. National Taiwan University, Taipei, Taiwan.

    • Lee Ling-Ling
  111. University of Würzburg, Biocenter, D97074 Wuerzburg, Germany.

    • K. Eduard Linsenmair
  112. Organization for Tropical Studies, Durham, North Carolina 27705, USA.

    • Elizabeth Losos
  113. USDA International Institute of Tropical Forestry, Río Piedras, Puerto Rico 00926.

    • Ariel Lugo
  114. Makerere University, Kampala, Uganda.

    • Jeremiah Lwanga
  115. Green Capacity Inc., New Florence, Pennsylvania 15944, USA.

    • Andrew L. Mack &
    • Debra D. Wright
  116. Museu Paraense Emílio Goeldi, Belém, Pará 66040-170, Brazil.

    • Marlucia Martins
  117. Ohio State University, Columbus, Ohio 43210, USA.

    • W. Scott McGraw
  118. Wildlife Conservation Society, Flores, Guatemala.

    • Roan McNab
  119. Universidad Federal do Pará, Belém, Pará 66040-170, Brazil.

    • Luciano Montag
  120. Lukuru Wildlife Research Foundation, Kinshasa, Democratic Republic of Congo.

    • Jo Myers Thompson
  121. Aarhus University, 4000 Roskilde, Denmark.

    • Jacob Nabe-Nielsen
  122. Nagoya University, Nagoya, Japan.

    • Michiko Nakagawa
  123. University of Waterloo, Waterloo, Ontario N2L 3G1, Canada.

    • Sanjay Nepal
  124. Kent State University, Kent, Ohio 44242, USA.

    • Marilyn Norconk
  125. Institute of Entomology, Ceske Budejovice, Czech Republic.

    • Vojtech Novotny
  126. University of Washington, Seattle, Washington 98195, USA.

    • Sean O'Donnell
  127. PNG Institute of Biological Research, Goroka, Papua New Guinea.

    • Muse Opiang
  128. University of Suriname, Paramaribo, Suriname.

    • Paul Ouboter
  129. 113-3885 Richet Rd, Prince George, British Columbia V2K 2J2, Canada.

    • Kenneth Parker
  130. Pondicherry University, Puducherry 605-014, India.

    • N. Parthasarathy
  131. Fundação Florestal, São Paulo, São Paulo 02377-000, Brazil.

    • Kátia Pisciotta
  132. Research Centre for Biology, Cibinong 16911, Indonesia.

    • Dewi Prawiradilaga
  133. University of Georgia, Athens, Georgia 30602, USA.

    • Catherine Pringle
  134. Strix Wildlife Consultancy, Singapore.

    • Subaraj Rajathurai
  135. Southern Illinois University, Carbondale, Illinois 62901, USA.

    • Ulrich Reichard
  136. Zoological Society of Milwaukee, Milwaukee, Wisconsin 53226, USA.

    • Gay Reinartz
  137. Estación de Biologia Chamela, Universidad Nacional Autónoma de México, Jalisco 48980, Mexico.

    • Katherine Renton &
    • Jorge Vega Rivera
  138. Danum Valley Field Centre, Sabah, Malaysia.

    • Glen Reynolds
  139. Oxford University, Oxford BN26 5UX, UK.

    • Vernon Reynolds
  140. San Diego State University, San Diego, California 92182, USA.

    • Erin Riley
  141. Museum für Naturkunde, Berlin, Germany.

    • Mark-Oliver Rödel
  142. City University of New York, New York 10065, USA.

    • Jessica Rothman
  143. Mahidol University, Bangkok 10400, Thailand.

    • Philip Round
  144. Research Institute for Humanity and Nature, Kyoto, Japan.

    • Shoko Sakai
  145. Karlsruhe University of Applied Sciences, Karlsruhe, Germany.

    • Gertrud Schaab
  146. National Zoological Park, Washington DC 20013, USA.

    • John Seidensticker
  147. Gola Forest Programme, Kenema, Sierra Leone.

    • Alhaji Siaka
  148. Wake Forest University, Winston-Salem, North Carolina 27106, USA.

    • Miles R. Silman
  149. University of California, Los Angeles, California 90095, USA.

    • Thomas B. Smith &
    • Benjamin Wang
  150. Av. Maalhães Barata 376, Belém, Pará 66040-170, Brazil.

    • Samuel Soares de Almeida
  151. University of Southern California, Los Angeles, California 90089, USA.

    • Craig Stanford
  152. Institute of Applied Ethnobotany, Pompano Beach, Florida 33069, USA.

    • Kristine Stewart
  153. Texas A & M University, Kingsville, Texas 78363, USA.

    • Kathryn E. Stoner
  154. Indian Institute of Science, Bangalore, India.

    • Raman Sukumar
  155. Georg-August-Universität, Göttingen, Germany.

    • Teja Tscharntke &
    • Matthias Waltert
  156. Wildlife Conservation Society, Bangui, Central African Republic.

    • Andrea Turkalo
  157. Centre for Cellular and Molecular Biology, Hyderabad, India.

    • Govindaswamy Umapathy
  158. 701, Vesta B, Lodha Paradise, Thane, India.

    • Meena Venkataraman
  159. Paluma Environmental Education Centre, Paluma, Queensland 4816, Australia.

    • Linda Venn
  160. Universidad Central de Venezuela, Maracay, Venezuela.

    • Carlos Verea
  161. Embrapa Roraima, Boa Vista, Roraima, Brazil.

    • Carolina Volkmer de Castilho
  162. Treasure Valley Math and Science Center, Boise, Idaho 83714, USA.

    • David Whitacre
  163. Rice University, Houston, Texas 77005, USA.

    • Ken Whitney
  164. Stony Brook University, Stony Brook, New York 11794, USA.

    • Patricia Wright
  165. Resources Himalaya Foundation, Kathmandu, Nepal.

    • Pralad Yonzon
  166. Gunung Palung National Park, West Kalimantan, Indonesia.

    • Franky Zamzani
  167. Deceased.

    • Elisabeth Kalko,
    • Samuel Soares de Almeida,
    • Navjot Sodhi &
    • Pralad Yonzon


W.F.L. conceived the study and coordinated its design, analysis and manuscript preparation. D.C.U., J.R. and M.K. conducted the interviews; C.J.A.B. assisted with data analysis and some writing; and S.P.S., S.G.L., M.C. and W.L. organized data or collected metadata. The remaining authors provided detailed interviews on protected areas and offered feedback on the manuscript.

Competing financial interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to:

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Supplementary information

PDF files

  1. Supplementary Information (2.1M)

    This file contains Supplementary Figures 1-6, Supplementary Text and Data, Supplementary Tables 1-6, additional references and a Supplementary Appendix, which comprises a non-interactive copy of an expert questionnaire.


  1. Report this comment #50648

    Hari Sridhar said:

    In this paper, Laurance and co-authors have tapped the expert opinions of 'veteran field biologists and environmental scientists' to understand the health of protected areas in the tropics worldwide. This is a novel and interesting approach and the dataset they have gathered is very impressive. Given that expert opinion can be subject to all kinds of biases and errors, it is crucial to demonstrate that expert opinion matches empirical reality. While the authors have tried to do this by comparing their results with empirical time-series datasets, I argue that their comparison does not serve the purpose of an independent validation.

    Using 59 available time-series datasets from 37 sources (journal papers, books, reports etc.), the authors find a fairly good match between expert opinion and empirical data (in 51/59 cases, expert opinion matched empirically-derived trend). For this comparison to serve as an independent validation, it is crucial that the experts were unaware of the empirical trends at the time of the interviews. However, this is unlikely to be true because, in most cases, the experts themselves were involved in the collection of the time-series datasets (at least 43/59 to my knowledge, from a scan of references in Supplementary Table 1). In other words, the same experts whose opinions were being validated were involved in collection of the data used for validation.

  2. Report this comment #50671

    William Laurance said:

    William Laurance, Corey Bradshaw and Susan Laurance respond as follows:

    Sridhar raises a fair and relevant point but one that, on careful examination, does not weaken our validation analysis.

    As detailed in our Supplementary Information, we made a concerted effort to locate fully independent time-series datasets against which to test our interview findings, but struggled to find usable overlap with the specific protected areas, guilds and potential environmental drivers evaluated in our study. Fortunately, we ultimately located 59 empirical time-series datasets that met several a priori criteria we established, including two important safeguards: (1) most were published only after our expert interviews were completed, thereby minimizing the exposure of most of our experts to these reports; and (2) each of the response variables we tested was derived by averaging up to 4-5 separate expert opinions, thereby diluting the impact of any one individual?s opinion (although we removed low-confidence opinions from our analysis).

    Ideally, one would exclude any empirical dataset in which our experts had any involvement at all, even as a minor author, but this was simply not possible. Most of the protected areas we studied had relatively few field biologists with long-term expertise, and most of these experts were included in our study (216 were co-authors). Had we excluded every potential validation study in which one of our experts had had even marginal involvement, we would have had little basis for validation. As it was, the 59 empirical time-series datasets we identified permitted us to test just a small fraction (1.6%) of the 3,589 expert responses generated by our study. Importantly, we acknowledged the limitations of our approach by stating in our Supplemental Information that the safeguards we imposed provided ?a more independent test? (not a fully independent test) of our interview data.

    These caveats aside, if Sridhar is correct that our validation analysis was compromised, one would expect the datasets in which our interviewed experts had any involvement to agree more frequently with the interview data than did those in which our experts had no involvement at all. Of the 59 validation studies, our co-authors had some involvement in 43, and no involvement in the remaining 16. The former agreed with our interview data in 88.4% of cases (38/43), and the latter in 81.3% (13/16). These minor differences did not differ statistically (Gadj=0.44, df=1, P=0.51; G-test for independence, adjusted for sample size).

    Hence, we suggest that the safeguards we imposed were reasonable given the severe constraints on suitable time-series datasets?limitations we readily acknowledged. Our safeguards appear to have been largely effective, as otherwise one would expect the frequency of agreement to differ between those validation tests in which our experts had some involvement versus those with no involvement at all.

  3. Report this comment #50686

    Fabio Roque said:

    Biodiversity is disproportionally concentrated in the tropics, with more than half of all known species inhabiting tropical forests. Although, reserves are not the only strategy to conserve biodiversity, they are believed to be highly cost effective in protecting it1. A relative wave of optimism followed the recent Biodiversity International Convention report that pointed to an increase in the number of reserves created within the last decade in the tropics2. Laurance et al.3, however, call our attention to a very serious concern: protected areas in the tropics may not be effectively protecting biodiversity. The authors go further and conclude that many tropical reserves are actually losing biodiversity, as they have reported a decrease in the abundance of various sensitive guilds - e.g., apex predators, stream-dwelling amphibians and large-seed old-growth trees - over the past 20 to 30 years. The study was based on a huge number of interviews, but given the practical consequences of this type of conclusion, we identified a major limitation that we believe deserves careful consideration. We suggest that the empirical data they use are not appropriate to infer the "health" state of reserves within the entire tropical region.
    According to the latest statistics from the UNEP World Conservation Monitoring Centre, there are now over 157,000 nationally designated protected areas covering about 12.7 per cent of the world?s land area outside Antarctica. Tropical reserves are not distributed homogeneously through the world?s continents and countries, so any study aiming to measure global tropical reserve "health" should carried be out using true stratified and representative samples that consider this inbalance in the distribution of reserves. Therefore, we suggest that regions with more reserves, in number and area, should be more extensively sampled if one is interested in evaluating biodiversity trends in tropical reserves. For example, in Brazil, one of the world's most mega-diverse countries, which has the largest tropical protected area system in the world with 310 federal, 568 state, 89 municipal, and 629 private reserves, totaling approximately 150 million ha in size (Brazilian Ministry of the Environment), Laurance et al.3 selected only 1 reserve in the Atlantic Forest (~430 ha) and three in the Amazon (together with ~143,000 ha). These reserves represent less than 0.004% of the area of Atlantic Forest reserves and 0.12 % of Amazon reserves in Brazil. Hence, their data set is not stratified or randomly sampled to assess a very complex issue, such as reserve "health", at least for a large piece of tropical world. This does not mean that Brazilian reserves are not threatened by anthropogenic pressures or that improvements in reserve managementare not needed. What we are suggesting is that simplistic approaches to assess reserve "heath" and unrepresentative sampling designs can result in more problems for conservation in the tropics (e.g., ill-intentioned argumentations that reserves are not important) than solutions based on global representative data also useful for regional or local decision-making. In short, although we applaud the initiative made by Laurance et al.3 in bringing this issue to our attention, we suggest their letter should be seen as a general opinion of a group of researchers about biodiversity trends in tropical reserves. It is not supported by global representative data in a statistical sense and the limitations of its inferences should have been at least considered in their original contribution.

    1. Rodrigues, A. S. L. et al. Effectiveness of the global protected area network in representing species diversity. Nature 408, 640-643 (2004).
    2. Global Biodiversity Outlook. Global Biodiversity Outlook 3. Available at http://gbo3.cbd.int/ (2010).
    3. Laurance, W. F. et al. Averting biodiversity collapse in tropical forest protected areas. Nature doi:10.1038/nature11318 (2012).

    Fabio de Oliveira Roque & Tadeu Siqueira
    1. Centro de Ciências Biológicas e da Saúde, Universidade Federal de Mato Grosso do Sul, Cidade Universitária, Caixa Postal 549, CEP 79070-900 - Campo Grande, MS, Brazil (E-mail: roque.eco@gmail.com)
    2. Departamento de Ecologia, Universidade Estadual Paulista - UNESP, Rio Claro, SP, Brazil (E-mail: tsiqueira @rc.unesp.br)

  4. Report this comment #50945

    Faye Fornasier said:

    Comment posted on behalf of William F. Laurance:

    Effectiveness of tropical reserves: Response

    William F. Laurance1*, Corey J. A. Bradshaw2, Susan G. Laurance1

    1Centre for Tropical Environmental and Sustainability Science (TESS) and School of Marine and Tropical Biology, James Cook University, Cairns, Queensland 4878, Australia
    2The Environment Institute and School of Earth and Environmental Sciences, University of Adelaide, Adelaide, South Australia 5005, Australia
    *Correspondence to W.F.L. (bill.laurance@jcu.edu.au)

    Roque and Siqueira1 suggest that, because protected areas are not evenly distributed across the world's tropical forest regions, conclusions based on our pantropical sample of 60 protected areas2 might lack statistical validity. This is a pertinent concern because we did hope to identify some broad trends in the biological 'health' of tropical forest reserves globally.
    However, our selection of tropical forest protected areas was in fact broadly representative, for several reasons:
    1) The 60 reserves we sampled were evenly stratified across the world's three major tropical forest regions: Africa (including Madagascar), the Americas (South and Central America plus the Caribbean), and the Asia-Pacific region (Southeast Asia, South Asia, Melanesia and tropical Australia). A total of 36 different nations were represented in this sample.

    2) Based on data from the World Database on Protected Areas (www.wdpa.org), we found no significant difference in the frequency of high-protection (IUCN Categories I-IV), multiple-use (Categories V-VI) and unclassified reserves between our sample of 60 protected areas and all 16,038 reserves found in the same tropical nations2.

    3) Likewise, we found no significant difference in the geographic isolation of our 60 reserves (travel time to the nearest city of >50,000 residents) compared to an equal number of reserves randomly stratified across the same 36 nations2.

    4) Finally, across the tropical nations represented in our study, we recently tested for and found a strong, positive relationship (rs=0.427, n=33, P=0.014; Spearman rank correlation); between the number of reserves we selected and current forest cover3 (China, Nepal and Australia were excluded from this comparison because most of their forest cover is non-tropical).
    From these findings we can conclude that the protected areas in our study (1) broadly sampled the world's major tropical forest regions and represent most tropical nations, (2) reasonably reflect the state of existing reserves in terms of their current legal-protection status, (3) are comparable to existing reserves in terms of their geographical isolation from nearby human populations, and (4) reasonably sampled, at a national scale, the large variability in tropical forest cover. Via all of these measures, we assert that our reserves were broadly representative.
    We do, nonetheless, concede that one aspect of our sampling strategy - one that Roque and Siqueira1 do not mention - might have created a subtle bias. It was impossible for us to sample reserves in a truly random fashion because we could only include those with some expert knowledge (in our study, any reserve with fewer than 10 journal publications and 4-5 experts willing to be interviewed was not considered2). We highlight this limitation because recent evidence based on a single reserve suggests wildlife poaching is reduced in areas where researchers are present4. If this finding applies more generally, then our conclusions regarding the condition of tropical protected areas might be slightly too optimistic, and one could underscore the potential benefits of sustained field research for tropical biodiversity.

    1. Roque, F.O., Siqueira, T. Effectiveness of tropical reserves. Nature (2012).
    2. Laurance, W. F. et al. Averting biodiversity collapse in tropical forest protected areas. Nature 489, 290-294 (2012).
    3. FAO. Global Forest Resources Assessment 2005 (U.N. Food and Agricultural Organisation [FAO], 2005).
    4. Campbell, G., Kuehl, H., Diarrassouba, A., N'Goran, P.K., Boesch, C. Long-term research sites as refugia for threatened and overharvested species. Biol. Lett. 7, 723-726 (2011).

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