Disentangling climate and disturbance driven tropical tree growth dynamics - A long-term dendroecology study of the full set of dominant tree species in a seasonal dry evergreen tropical forest in western Thailand

Abstract

Tropical forests in recent decades have been subject to changes in forest dynamics, in respect to forest growth and species composition. These changes could be occurring by climatic drivers or natural succession following past disturbances. To disentangle the climatic and disturbance related effects, research should focus on studying long-term growth dynamics in the full composition of a forest stand. This research will use long-term wood growth and composition proxies of 16 tree species, representing over 50% of the total stand basal area and the different guilds of the seasonal dry evergreen forest Huai Kha Khaeng in western Thailand. An intra-annual detail study of microcores will determine the drivers that initiate, stop and vary growth rates over a growing season. Wood anatomy together with chemical analysis of isotope ratios and trace element concentrations will determine the controlling environmental drivers during the growing season. The per species determined most reliable distinct annual proxy will subsequently be used as an annual ring boundary template by which age reconstruction can date large increment cores and their annual growth rates. This is especially needed to incorporate ringless tree species in the data set which eventually will lead to the ability to research all dominant tree species in the stand. An additional analysis to the past disturbance history in the forest plot comes from the growth suppression and release rates and varying age distribution in the different forest guild species. Ultimately this can answer if observed long-term growth fluctuation are caused by past disturbances or driven by changing climate variables.