Status of phenology studies in Asian tropical forests and the effects of sampling effort on accuracy of estimating phenology

Abstract

Phenology, the study of timings of life-history events in plants is important for individual fitness, community dynamics, and ecosystem functioning. Given the current context of climate change, understanding general patterns of phenology and shifts in these patterns is important. Within tropical forests, Asian tropics are highly underrepresented in global and large regional scale phenology studies. This is thought to be because of “poorer traditions” of studying phenology including poor sampling efforts. To understand the specific reasons for this, the status of Asian tropical phenology studies in terms of numbers, geographical coverage and sampling methods and efforts was examined. It was seen that though there were reasonable number of studies and most climatic and vegetative zones were represented, there was a dearth of long-term studies and the sampling efforts were not adequate. This can affect the robustness of results. The effect of sampling effort on accuracy of phenology estimates and detection of shifts in phenology for different populations was examined through a simulation study. It was seen that increasing sampling effort increased the accuracy of estimating phenology and decreased the number of years required to detect shifts in phenology. But the effect differed between replicate number and sampling frequency and also depended on the population. There is a need to increase the sampling efforts of phenology studies in Asian tropical forests in terms of duration of studies, sample size and sampling frequencies. The results of this study can help modify resource allocation for sampling effort, design better sampling strategies and maximise the efforts to understand long-term phenology patterns and hasten the process of understanding impacts of climate change.