POTENTIAL IMPACTS OF CLIMATE CHANGE ON TROPICAL FOREST ECOSYSTEMS

Transcription

1 POTENTIAL IMPACTS OF CLIMATE CHANGE ON TROPICAL FOREST ECOSYSTEMS

2 POTENTIAL IMPACTS OF CLIMATE CHANGE ON TROPICAL FOREST ECOSYSTEMS Edited by Adam Markham Energy and Climate Program, World Wildlife Fund, Washington, DC, U.S.A. Reprinted from Climatic Change Volume 39, Nos. 2-3, 1998 Springer-Science+Business Media, B.V.

3 A C.I.P. Catalogue record for this book is available from the Library of Congress. ISBN ISBN (ebook) DOI / Printed on acid-free paper All rights reserved 1998 Springer Science+ Business Media Dordrecht Originally published by Kluwer Academic Publishers in 1998 Softcover reprint of the hardcover 1st edition 1998 No part of the material protected by this copyright notice may be reproduced or utilised in any form or by any means, electronic or mechanical, including photocopying, recording or by any information storage and retrieval system, without written permission from the copyright owner

4 Contents ADAM MARKHAM I Potential Impacts of Climate Change on Tropical Forest Ecosystems. Guest Editorial MIKE HULME and DAVID VINER I A Climate Change Scenario for the Tropics 5 J. R. FLENLEY I Tropical Forests under the Climates of the Last 30,000 Years 37 K. WALSH and A. B. PITTOCK I Potential Changes in Tropical Storms, Hurricanes, and Extreme Rainfall Events as a Result of Climate Change 59 M. BONELL I Possible Impacts of Climate Variability and Change on Tropical Forest Hydrology 75 JOHANN GEORG GOLDAMMER and COLIN PRICE I Potential Impacts of Climate Change on Fire Regimes in the Tropics Based on MAGICC and a GISS GCM-Derived Lightning Model 133 CHRISTIAN KORNER I Tropical Forests in a COr Rich World 157 F. A. BAZZAZ I Tropical Forests in a Future Climate: Changes in Biological Diversity and Impact on the Global Carbon Cycle 177 WHENDEE L. SILVER I The Potential Effects of Elevated C02 and Climate Change on Tropical Forest Soils and Biogeochemical Cycling 197 THOMAS A. KURSAR I Relating Tree Physiology to Past and Future Changes in Tropical Rainforest Tree Communities 223 ROLF BORCHERT I Responses of Tropical Trees to Rainfall Seasonality and Its Long-Term Changes 241 PETER H. JIPP, DANIEL C. NEPSTAD, D. K. CASSEL, and C. REIS DE CARVALHO I Deep Soil Moisture Storage and Transpiration in Forests and Pastures of Seasonally-Dry Amazonia 255 RICHARD CONDIT I Ecological Implications of Changes in Drought Patterns: Shifts in Forest Composition in Panama 273 T. C. WHITMORE I Potential Impact of Climatic Change on Tropical Rain Forest Seedlings and Forest Regeneration 289 RICHARD T. CORLETT and JAMES V. LAFRANKIE, JR. I Potential Impacts of Climate Change on Tropical Asian Forests Through an Influence on Phenology 299 PHYLLIS D. COLEY I Possible Effects of Climate Change on Plant/Herbivore Interactions in Moist Tropical Forests 315

5 KAMALJIT S. BAWA and S. DAYANANDAN I Global Climate Change and Tropical Forest Genetic Resources 333 JAY R. MALCOLM I A Model of Conductive Heat Flow in Forest Edges and Fragmented Landscapes 347 LLOYD L. LOOPE and THOMAS W. GIAMBELLUCA I Vulnerability of Island Tropical Montane Cloud Forests to Climate Change, with Special Reference to East Maui, Hawaii 363 DAVID H. BENZING I Vulnerabilities of Tropical Forests to Climate Change: The Significance of Resident Epiphytes 379 MAUREEN A. DONNELLY and MARTHA L. CRUMP I Potential Effects of Climate Change on Two Neotropical Amphibian Assemblages 401 N. H. RAVINDRANATH and R. SUKUMAR I Climate Change and Tropical Forests in India 423 P. S. RAMAKRISHNAN I Sustainable Development, Climate Change and Tropical Rain Forest Landscape 443 NICK SALAFSKY I Drought in the Rain Forest, Part II. An Update Based on the 1994 ENSO Event 461

6 POTENTIAL IMPACTS OF CLIMATE CHANGE ON TROPICAL FOREST ECOSYSTEMS Guest Editorial Study of the potential effects of global warming and associated impacts on tropical forests remains one of the most neglected areas of climate change research. It is commonly assumed that because predicted global warming will generally be less near the equator than close to the poles, tropical forest ecosystems may be largely unaffected, especially when compared to the more obvious likely impacts of warming in the boreal forest zone. Policy discussions centered on tropical forest conservation often dismiss the threat of climatic change as quite insignificant in comparison to land-use change and other human impacts. It is certainly true that the driving forces behind the current, wholly unsustainable, rates of deforestation and degradation are predominantly unrelated to the apparent global warming trend. Nevertheless, an increasing understanding of tropical ecology is leading many scientists to the conclusion that many of these forests may be very sensitive to climatic change. Increasingly, it is being recognized that factors other than warming, including changes in hydrology, rainfall patterns and the frequency and intensity of storms and fires, may have far-reaching consequences. The manuscripts gathered in this special issue of Climatic Change were prepared for and (with the exception of two of them), presented at an international workshop, Potential Impacts of Climate Change on Tropical Forest Ecosystems, which took place in San Juan, Puerto Rico, April1995. The workshop was co-sponsored by the World Wildlife Fund (WWF) and the International Institute of Tropical Forestry (IITF) at Rio Piedras. Its primary objective was to bring together a multidisciplinary group of scientists in order to advance understanding of the sensitivity and vulnerability of different types of tropical forests to rapid climatic change. The meeting also aimed to identify future research needs and to discuss the issue of which types of tropical forests may be most vulnerable to climatic change. Prior to the meeting, participants were provided with a climate scenario developed from observed climatology, a simple upwelling-diffusion energy balance model (called MAGICC) and results of a Hadley Centre coupled ocean-atmosphere GCM experiment (Hulme and Viner, 1998). As a result, participating ecologists and conservation biologists, who had little previous experience with climate impacts assessments, were able to visualize at least one possible set of changes that could impact their area of study. Climatic Change 39: , [1]

7 142 GUEST EDITORIAL As can be seen from this collection of papers, the workshop was successful in pulling together a substantial amount of new thinking on the topic under discussion. Representing perhaps the first major review of the range of possible effects of climate change on tropical forests, this issue of Climatic Change will hopefully catalyze further study of and debate about this important area. It became clear during the workshop that certain types of tropical forest ecosystems may be especially vulnerable to climate change, particularly tropical montane cloud forests and closed evergreen rain forests, which are being opened up to logging and land-use change. Epiphytic plants and tropical amphibians were identified as potentially sensitive and possible indicators of change. A consensus emerged among the workshop participants that the most significant threats to tropical forest ecosystems would be likely to come from drying trends, changes in rainfall patterns and seasonality (Bawa and Markham, 1995). Significant changes in species distribution and composition could also be expected, leading to extinction in the most sensitive ecosystems. By far the most serious synergistic factor identified as increasing the risk to tropical forests was fragmentation. Although the paleoecological evidence indicates that tropical forests have been able to respond to rapid climatic changes in the past, current forest loss and fragmentation make distributional changes almost impossible for most tropical forest systems today. Fragmentation may even make forests directly more susceptible to warming impacts (Malcolm, 1998). Reducing fragmentation can contribute strongly to maintaining biodiversity and ecosystems services as well as to building the resilience needed to mitigate climate change impacts (Whitmore, 1998). The papers collected here provide an excellent starting point for a much-needed new focus on potential climate change impacts on tropical forests and their myriad species. Although the results of the WWFIIITF workshop tend to pose more questions than they answer, there is no doubt that this is an area that deserves greater, and more sustained, attention. It is also clear that there would be much to be gained from efforts to provide the kind of regional climate scenarios that can help biologists determine the vulnerability and sensitivity of these ecosystems. I would like to acknowledge all those who provided help and advice in the planning and organization of the Puerto Rico workshop. They include Fred Scatena, Ariel Lugo, Sandra Woods, Tim Whitmore, Gary Hartshorn, Sarah Laskin, Jay Malcolm and Mike Hulme. Finally, I thank the authors for their patience and forbearance in what has been a long gestation period for this special issue. References Bawa, K. S. and Markham, A.: 1995, 'Climate Change and Tropical Forests', Trends Ecol. Evol. 10, Hulme, M. and Viner, D.: 1998, 'A Climate Change Scenario for the Tropics', Clim. Change 39 (this volume). Malcolm, J. R.: 1998, 'A Model of Conductive Heat Flow in Forest Edges and Fragmented Landscapes', Clim. Change 39 (this volume). [2]

8 GUEST EDITORIAL 143 Whitmore, T. C.: 1998, 'Potential Impact of Climatic Change on Tropical Rain Forest Seedlings and Forest Regeneration', Clim. Change 39 (this volume). Director, Energy and Climate Program, World Wildlife Fund, 1250 Twenty-Fourth Street NW, Washington, DC , U.S.A. ADAM MARKHAM [3]