Fires are a key environmental driver that modifies ecosystems and global biodiversity. Within biodiverse tropical and subtropical regions, fire occurrence has increased in recent decades and is predicted to increase due to climate and land use changes. Fire can have both negative and positive impacts on biodiversity and ecosystem functioning. Moreover, the fire pattern is also changing in these regions due to fire suppression and fire ignition measures. The impact of fire on biodiversity and ecosystem is very complex and can vary according to taxa, fire variables, level of disturbance and historical exposure to fire. To add more knowledge and shed light on this intricate relationship between fire and biodiversity, I carried out a pan-tropical analysis on the impact of fire and post-fire recovery on the taxonomic, phylogenetic, and functional diversity of plant communities using data from published field-level studies.
In Chapter 2, this thesis addresses this issue by exploring the impact of fire on taxonomic diversity (species richness and species turnover) of four life form groups: trees/shrubs, forbs, graminoids and climbers. In Chapter 3, I constructed the phylogenetic trees of four life form groups to establish the impact of fire on phylogenetic diversity, including phylogenetic clustering or phylogenetic over-dispersion. In Chapter 4, I collected the traits data for the trees/shrubs and worked on the functional diversity, functional richness, and functional turnover.
This thesis found that the impact of fire and the recovery of plant communities after a fire depends not only on the fire variables (time since fire and prescribed vs. non-prescribed fire) but also on the life form (trees/shrubs, forbs, graminoids, and climbers), protection status (protected vs non-protected), and a biome with the level of historical exposure to fire. Fire impacts were found to vary across the taxonomic, phylogenetic, and functional diversity as well as across the life forms that are underrepresented in ecological studies, such as forbs, graminoids and climbers. My analysis revealed that the impact could continue to worsen due to increasing fire activities arising from climate and land use change. Although my research adds complementary knowledge to the existing knowledge, it should still be interpreted cautiously due to the limited dataset, and, in some cases, limited predictive power of the models. Hence, this research informs the need to conduct comparative studies of different under-represented life forms and focus more on phylogenetic and functional diversity.
