Drivers of soil organic carbon stock during tropical forest succession

Soil organic matter contributes to productivity in terrestrial ecosystems
and contains more carbon than is found in the atmosphere. Yet, there is
little understanding of soil organic carbon (SOC) sequestration processes
during tropical forest succession, particularly after land abandonment
from agriculture practices. Here we used vegetation and environmental data
from two large-scale surveys covering a total landscape area of 20,000 ha
in Southeast Asia to investigate the effects of plant species diversity,
functional trait diversity, phylogenetic diversity, aboveground biomass,
and environmental factors on SOC sequestration during forest succession.
We found that functional trait diversity plays an important role in
determining SOC sequestration across successional trajectories. Increases
in SOC carbon storage were associated with indirect positive effects of
species diversity and succession age via functional trait diversity, but
phylogenetic diversity and aboveground biomass showed no significant
relationship with SOC stock. Furthermore, the effects of soil properties
and functional trait diversity on SOC carbon storage shift across
elevation. Synthesis: Our results suggest that reforestation and
restoration management practices that implement a trait-based approach by
combining long-lived and short-lived species (conservative and acquisitive
traits) to increase plant functional diversity could enhance SOC
sequestration for climate change mitigation and adaptation efforts, as
well as accelerate recovery of healthy soils.