Data from: Effects of restoration on tree communities and carbon storage in rainforest fragments of the Western Ghats, India

Ecological restoration is a leading strategy for reversing biodiversity
losses and enhancing terrestrial carbon sequestration in degraded tropical
forests. There have been few comprehensive assessments of recovery
following restoration in fragmented forest landscapes, and the efficacy of
active versus passive (i.e., natural regeneration) restoration remains
unclear. We examined 11 indicators of forest structure, tree diversity and
composition (adult and sapling), and aboveground carbon storage in 25
pairs of actively restored (AR; 7–15 yr after weed removal and
mixed-native tree species planting) and naturally regenerating (NR) plots
within degraded rainforest fragments, and in 17 less-disturbed benchmark
(BM) rainforest plots in the Western Ghats, India. We assessed the effects
of active restoration on the 11 indicators and tested the hypothesis that
active restoration effects increase with isolation from contiguous and
relatively intact rainforests. Active restoration significantly increased
canopy cover, adult tree and sapling density, adult and sapling species
density (overall and late successional), compositional similarity to
benchmarks, and aboveground carbon storage, which recovered 14–82% toward
BM targets relative to NR baselines. By contrast, tree height–diameter
ratios and the proportion of native saplings did not recover consistently
in actively restored forests. The effects of active restoration on canopy
cover, species density (adult), late successional species density (adult
and sapling), and species composition, but not carbon storage, increased
with isolation across the fragmented landscape. Our findings show that
active restoration can promote recovery of forest structure, composition,
and carbon storage within 7–15 yr of restoration in degraded tropical
rainforest fragments, although the benefits of active over passive
restoration across fragmented landscapes would depend on indicator type
and may increase with site isolation. These findings on early stages of
recovery suggest that active restoration in ubiquitous fragmented
landscapes of the tropics could complement passive restoration of degraded
forests in less fragmented landscapes, and protection of intact forests,
as a key strategy for conserving biodiversity and mitigating climate
change.