Understanding the effects of tropical rainforest fragmentation on tree communities and carbon storage: a functional traits approach

Introduction: What conservation problem or question does your study address?
The conservation of biodiversity and ecosystem services in the tropics is increasingly dependent on forests that are fragmented and disturbed. However, the mechanisms by which fragmentation alters the structure and functioning of ecosystems remain poorly understood. In this study, we use an analysis to plant functional traits to gain insights into the processes by which rainforest fragmentation alters tree community composition and carbon storage.

Methods: What were the main research methods you used?
The study employed an analysis of plant functional traits to examine linkages between forest fragmentation, tree community turnover and carbon storage potential. The objectives were (1) to identify the traits which best predict tree community turnover from contiguous to fragmented forests, and (2) identify relationships between the traits which structure tree communities in fragments and those which determine carbon storage potential. The study was conducted in nine contiguous and nine fragmented rainforests in the Western Ghats Mountains. Tree communities were sampled using replicated inventory plots. A set of plant functional traits which relate to key life history processes were sampled following standard protocols. Inter-trait relationships were described using pairwise correlations and trait-fragmentation interactions were identified using mixed-effects models.

Results: What are your most important results?
Functional traits related to seed dispersal processes were identified as the most important predictors of community turnover from contiguous to fragmented forests, with fragments dominated by small-seeded species. At the community level, seed size was positively associated with species’ adult heights, suggesting the structuring of tree communities by altered seed dispersal processes may affect carbon storage by promoting shorter-statured forests over time.

Discussion: What are your important discussion points and what is the relevance of your results to conservation (if any)?
While the role of local edge effects in structuring tree communities and reducing carbon storage is widely recognized, our results suggest that community turnover and carbon losses may be driven by altered seed dispersal processes acting at broader landscape scales. Alongside improved protection at the site level, efforts to secure connectivity at landscape-scales may be essential to sustain biodiversity and ecosystem services over time in fragmented landscapes.