The Effects of Climate Change on Tree Phenology for Forest Restoration in Northern Thailand

ABSTRACT: The current world climate is rapidly changing and affecting physical and biological environments. Some abiotic factors have an influence on tropical forest ecosystems. Each flowering plant has different responses of leafing, flowering and fruiting phenophases. This project studied associations between changes in abiotic factors (e.g. air temperature, rainfall, and relative humidity) and evergreen forest tree phenology of 13 tree species (60 individuals), between two time periods 21 years apart: 1994-1998 and 2015-2019 The study was performed along the fig-tree nature trail at about 1,000 m above sea level in Doi Suthep-Pui National Park, Chiang Mai province, northern Thailand. Phenological events were monitored during March 2019 – February 2020 using the crown density method. Average air temperature changed significantly between the two periods (P<0.05, paired t-test). Aphanamixis polystachya and Castanopsis acuminatissima had extended flowering phenophases in the later time period whereas Ficus microcarpa and Styrax benzoides flowered earlier. Changes in tree phenology were associated with changes in air temperature, relative humidity and rainfall. Such data may be useful for forest conservation and restoration, and related research. Finally, the author recommends continuing to survey all the species to follow future phenological changes.