Notícias

Aim Tropical forests store 25% of global carbon and harbour 96% of the world’s
tree species, but it is not clear whether this high biodiversity matters for carbon
storage. Few studies have teased apart the relative importance of forest attributes
and environmental drivers for ecosystem functioning, and no such study exists for
the tropics.
Location Neotropics.
Methods We relate aboveground biomass (AGB) to forest attributes (diversity
and structure) and environmental drivers (annual rainfall and soil fertility) using
data from 144,000 trees, 2050 forest plots and 59 forest sites. The sites span the
complete latitudinal and climatic gradients in the lowland Neotropics, with rainfall
ranging from 750 to 4350 mm year−1.Relationships were analysed within forest sites
at scales of 0.1 and 1 ha and across forest sites along large-scale environmental
gradients.We used a structural equation model to test the hypothesis that species
richness, forest structural attributes and environmental drivers have independent,
positive effects on AGB.
Results Across sites, AGB was most strongly driven by rainfall, followed by
average tree stem diameter and rarefied species richness, which all had positive
effects on AGB. Our indicator of soil fertility (cation exchange capacity) had a
negligible effect on AGB, perhaps because we used a global soil database. Taxonomic
forest attributes (i.e. species richness, rarefied richness and Shannon diversity)
had the strongest relationships with AGB at small spatial scales, where an
additional species can still make a difference in terms of niche complementarity,
while structural forest attributes (i.e. tree density and tree size) had strong relationships
with AGB at all spatial scales.
Main conclusions Biodiversity has an independent, positive effect on AGB and
ecosystem functioning, not only in relatively simple temperate systems but also in
structurally complex hyperdiverse tropical forests. Biodiversity conservation
should therefore be a key component of the UN Reducing Emissions from Deforestation
and Degradation strategy.