PLANT-WILDLIFE DYNAMICS IN THE TROPICAL RAINFOREST: PHENOLOGY, TROPHIC INTERACTIONS, AND HABITAT CONNECTIVITY

The tropical rainforests of Borneo are particularly distinctive for their inter-annual phenology, with supra-annual mast fruiting events that cause dramatic fluctuations in fruit availability. Tracking its phenology is therefore vital for forest wildlife, especially frugivores and granivores whose populations depend on these resources. This dissertation investigates animal–habitat dynamics in Borneo, examining it from the perspective of plant phenology, animal responses, and restoration practices. In the first chapter, I examined phenological change in rainforests of Borneo, focusing on tracking dipterocarp tree flowering using unoccupied aerial vehicles (UAVs). Dipterocarps exhibit the supra-annual cycle, during which individual trees bloom for four to five weeks. This short duration, coupled with persistent cloud cover, makes it difficult to monitor flowering using space-borne remote sensing. I demonstrated that UAV imagery, with spatial resolutions ranging from 20 centimeters to 5 meters, can reliably distinguish flowering in individual trees, highlighting the potential of UAVs to provide large-scale, high-resolution phenological monitoring in tropical forests. In the second chapter, I investigated how the fruiting of dipterocarps influences habitat use across trophic levels, drawing parallels to bottom-up cascades observed in temperate systems. I tested whether pulses in dipterocarp fruit availability propagate through animal communities using Structural Equation Modelling (SEM). My results revealed that resource pulses significantly influenced certain primary consumers but had little detectable effect on secondary consumers. The lack of response at higher trophic levels suggests that tropical animal communities may be buffered against cascading effects of pulsed resources, perhaps due to the presence of alternative food sources or the dominance of large-bodied granivores that mostly lack predators. Because many tropical rainforest animals must remain mobile to track resources, maintaining and restoring landscape connectivity is essential to support their movements. In my final chapter, I conducted a systematic review of the literature on forest restoration in Malaysian Borneo to assess whether indicators reported included measures of wildlife connectivity. My analysis revealed that none of the reviewed studies incorporated landscape scale connectivity indicators, highlighting a major gap in ensuring restoration outcomes for wildlife. I outlined recommendations to improve restoration practices, especially towards achieving the Kunming–Montreal Global Biodiversity Framework Target 2.

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