Historical distribution of Sundaland’s Dipterocarp rainforests at Quaternary glacial maxima

Abstract

The extent of Dipterocarp rainforests on the emergent Sundaland landmass in Southeast Asia during Quaternary glaciations remains a key question. A better understanding of the biogeographic history of Sundaland could help explain current patterns of biodiversity and support the development of effective forest conservation strategies. Dipterocarpaceae trees dominate the rainforests of Sundaland, and their distributions serve as a proxy for rainforest extent. We used species distribution models (SDMs) of 317 Dipterocarp species to estimate the geographic extent of appropriate climatic conditions for rainforest on Sundaland at the last glacial maximum (LGM). The SDMs suggest that the climate of central Sundaland at the LGM was suitable to sustain Dipterocarp rainforest, and that the presence of a previously suggested transequatorial savannah corridor at that time is unlikely. Our findings are supported by palynologic evidence, dynamic vegetation models, extant mammal and termite communities, vascular plant fatty acid stable isotopic compositions, and stable carbon isotopic compositions of cave guano profiles. Although Dipterocarp species richness was generally lower at the LGM, areas of high species richness were mostly found off the current islands and on the emergent Sunda Shelf, indicating substantial species migration and mixing during the transitions between the Quaternary glacial maxima and warm periods such as the present.Quaternary | last glacial maximum | Sundaland | Dipterocarpaceae | species distribution model

Neotropical forest expansion during the last glacial period challenges refuge hypothesis

“…In addition, the vast continental shelf has been completely ignored in paleomodeling studies of the Atlantic Forest, despite its evolutionary significance in other tropical areas, such as Southeast Asia, where widespread rainforest covered the exposed Sunda shelf during the LGM (31,32). These facts show that the predominantly glacial Quaternary environment is the norm, characterized by cooler climate, significantly lower sea levels, and slightly reduced precipitation, which was still enough to keep large stretches of rainforest instead of small refugia.…”

A review of the Cholevinae from the island of Borneo (Coleoptera, Leiodidae)

“…Sundaland comprises the present-day Malay Peninsula, the islands of Sumatra, Java, and Borneo, as well as the shallow seas in between. Recent paleoclimatic modelling (Raes et al 2014) suggests that even during cooler periods of marine regression, evergreen wet forests dominated the area that now comprises Borneo. This, and the fact that the island, because of its mountainous character (with Gunung Kinabalu reaching almost 4,100 m) contains a great variety of habitats, has generated and maintained a rich biodiversity, not least in its soil and litter-dwelling invertebrate fauna (e.g., Hanski and Hammond 1986, Rahman et al 2002, Liew et al 2010).…”

Genetic structure and post‐glacial expansion ofCornus floridaL. (Cornaceae): integrative evidence from phylogeography, population demographic history, and species distribution modeling

“…Two GCMs (Global Circulation Models; CCSM and MIROC) were used to project the species distribution. The variable values from the two models were averaged to generate an average projection of LGM distribution, following recent publications (Harrison et al, 2014;Raes et al, 2014). CCSM is the GCM from National Center for Atmospheric Research (USA), and MIROC is the GCM from Japan Agency for Marine-Earth Science and Technology.…”

“…CCSM is the GCM from National Center for Atmospheric Research (USA), and MIROC is the GCM from Japan Agency for Marine-Earth Science and Technology. These two GCMs are widely used in predicting past species distributions (e.g., Rojas, 2013;Harrison et al, 2014;Raes et al, 2014). For the future projections, results of the two GCMs under A2a and B2a, respectively, were combined to provide a consensus map of the species distribution following Porretta et al, (2012).…”