Data from: Seed size predicts community composition and carbon storage potential of tree communities in rainforest fragments in India’s Western Ghats

Fragmentation is ubiquitous across tropical forests and drives marked
shifts in tree community composition by differentially affecting species’
dispersal, establishment and survival. Such compositional shifts can
potentially alter ecosystem-level properties such as above-ground carbon
storage, but our understanding of the factors linking compositional shifts
to carbon storage is limited. We compared tree communities of contiguous
and fragmented tropical rainforests in the Western Ghats (India) and
assessed the ability of various plant functional traits associated with
seed dispersal, establishment and survival processes to predict species’
responses to fragmentation. Further, we assessed relationships between
functional traits that predict tree community turnover and those that
govern carbon storage to examine how fragmentation effects on species’
composition can alter the ability of tree communities to store carbon.
Seed size, as indexed by seed length, was the best predictor of species’
responses, with larger-seeded species declining in fragments. Across
species, seed length was positively correlated with maximum attainable
height, which decreased by 10% on average at the community level in
fragments. Such shifts towards smaller-seeded communities could decrease
forest stature and reduce above-ground carbon stocks by 8%. Synthesis and
applications. Our study highlights a previously undescribed mechanism by
which fragmentation-driven declines of large-seeded tree species can
reduce above-ground carbon stocks by promoting shorter-statured forests.
These results imply that strict protection alone might be insufficient,
and that a multi-pronged conservation strategy would be required to
sustain carbon stocks in tropical forest fragments. Such interventions
will need to combine restoration programmes for large-seeded tree species
in fragments with broader-scale efforts to maintain hospitable and
well-connected landscapes for their seed dispersers.