Data from: Incorporating intraspecific trait variation into functional diversity: impacts of selective logging on birds in Borneo

As conservation increasingly recognizes the importance of species’
functional roles in ecosystem processes, studies are shifting away from
measuring species richness towards measures that account for the
functional differences between species in a community. These functional
diversity (FD) indices have received much recent attention and refinement,
but their greatest limitation remains their inability to incorporate
information about intraspecific trait variation (ITV). We use an
individual-based model to account for ITV when calculating the functional
diversity of two avian communities in Borneo; one in primary (unlogged)
forest and one in selectively logged forest. We deal with the scarcity of
trait data for individual species by developing a simulation approach,
taking data from the literature where necessary. Using a bootstrapping
procedure, we produce a range of ecologically feasible FD values taking
account of ITV for five commonly used FD indices, and we quantify the
confidence that can be placed in these values, using a newly developed
bootstrapping method: btFD. We find that incorporating ITV significantly
alters the FD values of all indices used in our models. The rank order of
FD for the two communities, indicating whether diversity was higher in
primary or selectively logged forest, is largely unchanged by the
inclusion of ITV. However, by accounting for ITV, we are able to reveal
previously unrecognized impacts of selective logging on avian functional
diversity through a narrower dispersion of individuals in functional trait
space in logged forest. Our results highlight the importance of
incorporating ITV into measures of functional diversity, whilst our
simulation approach addresses the frequently encountered difficulty of
working with sparse trait data and quantifies the confidence that should
be placed in such findings.