Microtopographic specialization and flexibility in tropical peat swamp forest tree species

Abstract

AbstractTropical tree species distributions are determined by a wide range of biotic and abiotic factors, including topography and hydrology. Tropical peat swamp forests (TPSFs) are characterized in part by small‐scale variations in topography (‘hummocks’ and ‘hollows’) that create distinct microhabitats and thus may contribute to niche diversification among TPSF tree species. Using tree elevations calibrated to daily peat water levels collected using a data logger and a permutation test, we evaluated topographical microhabitat preferences for 21 tree species in a relatively undisturbed TPSF in Central Kalimantan, Indonesia, to determine whether these species show preferential association with hummocks or hollows and to quantify the prevalence of microhabitat specialization among them. Only one species, Tetractomia tetrandrum, emerged as a hollow specialist, with no hummock specialists among the species tested. The remaining 20 species, including Psydrax dicoccos, which had the lowest mean observed elevation, and Maasia hypoleuca, which had the highest mean observed elevation, showed no clear microtopographic preference. This suggests that many TPSF species may be resilient to the natural hydrologic variations that occur in relatively intact peat swamp forests. Such studies of microtopographic preferences of tree species in TPSF and other wetland forest ecosystems can inform selection of tree species for reforestation projects, and potentially also provide information on how future climate change may impact these habitats and their resident tree species.