Functional diversity of the avian assemblages better than taxonomic diversity in capturing the effect of protection

Protected areas (PAs) are the cornerstones of conservation and have been
shown to support higher density of conservation-dependent species. The
success of PAs has been attributed to their ability to mitigate both
forest loss and forest degradation. Effectiveness of PAs is conventionally
measured in terms of species diversity; evidence for the consequences of
protection on the functional diversity of species assemblages is scarce.
We utilized the Kerala Bird Atlas data to quantify alpha diversity, beta
diversity, and functional diversity from 300 sites within protected and
non-protected forests along the Western Ghats. Of the total forest cover
in Kerala, about one-fourth is under protection, the rest constitute
reserve forest (RF). We tested if various metrics of biodiversity differ
across PAs and adjacent RFs and which metric better captures this
difference. Results show that the effectiveness of protection varies
across guilds and does not seem to impact overall species richness. PAs
are effective at the level of assemblage composition, and support higher
abundance of species of conservation-concern. Species diversity did not
vary with the protection status. Functional richness was high in PA while
functional dispersion was high in RF. The effect of protection was more
prominently visible in terms of functional diversity than species
diversity. Such empirical data may broaden our understanding of the PAs
and assist in monitoring efforts.