The overall objective of this dissertation is to ‘gain increased understanding of the processes that govern plant species composition and structure of floodplain vegetation in Nong thung tong Non-Hunting Area’, an isolated and threatened 61.5 km2 patch of native floodplain forest in Southern Thailand. In the dissertation Mr Ponlawat Pattarakulpisutti presents results from a set of compatible field surveys and experiments in four separate data chapters (chapters 2 – 5). A general introduction (chapter 1) highlights our state of understanding of the study system and highlights the mechanisms of flooding tolerance among species, and how it should drive species distributions in these forests. It provides the broader context for the study. A general discussion (chapter 6), aims to tie everything together in the end. The four data chapters specifically showcase;
a. A field vegetation survey, shows how species differ in occurrence among predefined flooding landforms and how their distribution is (co)determined by a set of abiotic factors (soil fertility, clay content, land use history etc.), using multivariate ordination techniques (NMDS). The derived species distributions and flooding regimes serve to justify species selection for experimental work in the following chapters,
b. A seedling growth and survival experiment on four dominant tree species subjected to different flooding and recovery from flooding treatments shows that species differ markedly in flooding tolerance.
c. A seed flotation and viability after flooding experiment again shows some differences among selected species, and
d. The final data chapter assesses the natural regeneration and recruitment of species in the field.
As very little is known about floodplain forest ecology in general, and especially the threatened floodplain forests of Thailand, this dissertation should be considered as a relevant and timely piece of work. This dissertation will add new and original understanding to the broader field of floodplain forest ecology.