Climate change adaptation for conservation in Madagascar

0 Lee Hannah, Radhika Dave, Porter P Lowry II, Sandy Andelman, Michele Andrianarisata, Luciano Andriamaro, Alison Cameron, Robert Hijmans, Claire Kremen, James MacKinnon, Harison Hanitriniaina Randrianasolo, Sylvie Andriambololonera, Andriamandimbisoa Razafimpahanana, Herilala Randriamahazo, Jeannicq Randrianarisoa, Philippe Razafinjatovo, Chris Raxworthy, George E Schatz, Mark Tadross and Lucienne Wilm 1 Conservation International , PO Box 5178, Antananarivo 101, Madagascar 2 Missouri Botanical Garden, PO Box 299, St Louis, MO 63166-0299, USA 3 Departement Systematique et Evolution, Museum National d'Histoire Naturelle , 75213 Paris Cedex 05, France 4 Conservation International , 2011 Crystal Drive, Arlington, VA 22202, USA 5 Wildlife Conservation Society, BP 8500, Antananarivo 101, Madagascar 6 Missouri Botanical Garden, BP 3391, Antananarivo 101, Madagascar 7 International Rice Research Institute , Los Banos, Laguna, DAPO Box 7777, Metro Manila, The Philippines 8 Department of Environmental Sciences , Policy and Management, University of California , Berkeley, CA 94720, USA 9 Climate Systems Analysis Group, University of Cape Town , Private Bag X3, Rondebosch 7701, Republic of South Africa 10 American Museum of Natural History, Central Park West at 79th Street , New York, NY 10024, USA Articles on similar topics can be found in the following collections Receive free email alerts when new articles cite this article - sign up in the box at the top right-hand corner of the article or click here References Subject collections Email alerting service To subscribe to Biol. Lett. go to: http://rsbl.royalsocietypublishing.org/subscriptions Global change biology Opinion piece Climate change adaptation for conservation in Madagascar 1. INTRODUCTION Madagascars imperilled biota are now experiencing the effects of a new threatclimate change (Raxworthy et al. 2008). With more than 90% endemism among plants, mammals, reptiles and amphibians, the stakes are high. The pristine landscapes that allowed this exceptional biodiversity to survive past climate changes are largely gone. Deforestation has claimed approximately 90% of the islands natural forest (Ingram & Dawson 2005; Harper et al. 2007) and what remains is highly fragmented, providing a poor template for large-scale species range shifts. The impacts of current and future climate change may therefore be much different than past impacts, with profound implications for biodiversity. We review evidence of past response to climate change, models of future change and projected biological response, developing insights to formulate adaptation actions for reducing extinction in Madagascars biota. We then explore the cost of implementing actions and examine new income opportunities developing through efforts to mitigate climate change. 2. PAST CLIMATE CHANGE AND BIOLOGICAL RESPONSE The diversity of Madagascars climates, their variability over time and the contrast between the eastern and western slopes have been invoked to explain patterns of endemism (Perrier de la Bathie 1921; Dewar & Richard 2007). Climate change during past glaciations suggests mechanisms shaping distributions of some modern taxa ( Wilme et al. 2006). Major climate changes accompanied global glaciations, with drier/ cooler and wetter/hotter periods and rapid transitions (Wells 2003). The fauna has been shaped by climatic unpredictability (Dewar & Richard 2007) and riverine forests have served as pathways or refugia for many forest taxa (Ganzhorn & Sorg 1996). Upland refugia have been proposed in areas retaining relict vertebrate and plant populations (Rakotondrainibe 2000; Andreone et al. 2005). Rivers with high-elevation headwaters have served as palaeorefuges, maintaining riparian forest where species retreated during the driest periods. As conditions became wetter, riparian habitats extended into tributaries with lower headwaters, opening dispersal Electronic supplementary material is available at http://dx.doi.org/ 10.1098/rsbl.2008.0270 or via http://journals.royalsociety.org. One contribution of 12 to a Special Feature on Global change and biodiversity: future challenges. corridors. Retreatdispersion watersheds (figure 1, AJ ) with higher headwaters are separated by others originating at lower elevations (figure 1, watersheds 112) that were isolated during dry periods; contraction and loss of riparian habitats rendered the latter more isolated, leading to high endemism. The distributions of many animal groups can be explained by the retreatdispersion hypothesis ( Wilme et al. 2006); preliminary analyses indicate that the flora also conforms to this scenario. Conserving riverine corridors and intervening isolated forest blocks are thus critical to maintaining resilience in the face of future climate change. 3. PROJECTED FUTURE CLIMATE CHANGE AND RESPONSE Pronounced climate change is expected in this century. Projections indicate mean temperature increases of 1.12.68C throughout the island (figure 2a) with greatest warming in the south and least along the coast and in the north ( Tadross et al. 2008). These spatial characteristics have important biological implications because the south is already the driest region and the highly fragmented eastern forest is vulnerable to drying. Projections for median rainfall, from statistical downscaling of six general circulation models (Hewitson & Crane 2006), are presented in figure 2b and discussed by Tadross et al. (2008). Rainfall should increase in summer ( JanuaryApril), and winter ( JulySeptember) will be drier along the southeast coast by 2050 but wetter elsewhere. Dynamic global vegetation model (BIOME and MAPPS) projections indicate Madagascar will lose 1127% of its current habitat due to climate change if range migrations are possible ( perfect dispersal) and 1750% if not (no dispersal; Malcolm et al. 2006). They also indicate biome migration rates of 144532 m yrK1, significantly higher than average post-glacial rates (100200 m yrK1). Models for 74 endemic plant species indicate significant changes in suitable climate space by 2080 in nearly all cases (Schatz et al. 2008, table 1). Substantial agreement was found among six projections made using three climate models and IPCC (A2a and B2a) scenarios (see electronic supplementary material). Eighteen per cent of species were projected to expand in range and 45% to contract, even under the optimistic full dispersal assumption. Thirty seven per cent had mixed projections. Expansion/contraction is not the only response; as elsewhere, projections include range shifts along altitudinal and moisture gradients. Full assessment of threat from climate change must consider potential range size change combined with ability to migrate sufficiently. In southwestern Madagascar, where projected temperature changes are greatest, many species are predicted to undergo range expansion, but future distributions overlap very little with current ones, suggesting mig (...truncated)