Data from: Burning savanna for avian species richness and functional diversity

Prescribed fire is used throughout fire-prone landscapes to conserve
biodiversity. Current best practice in managing savanna systems advocates
methods based on the assumption that increased fire-mediated landscape
heterogeneity (pyrodiversity) will promote biodiversity. However,
considerable knowledge gaps remain in our understanding of how savanna
wildlife responds to the composition and configuration of pyrodiverse
landscapes. The effects of pyrodiversity on functional diversity has
rarely been quantified and assessing this relationship at a landscape
scale which is commensurate with fire management is important for
understanding mechanisms underlying ecosystem resilience. Here, we assess
the impact of spatiotemporal variation in a long-term fire regime on avian
diversity in North West Province, South Africa. We examined the
relationship between (a) species richness, (b) three indices of functional
diversity (i.e., functional richness, functional evenness and functional
dispersion) and four measures of pyrodiversity, the spatial extents of
fire age-classes, and habitat type at the landscape-scale. We then used
null models to assess differences between observed and expected functional
diversity. We found that the proportion of newly-burned (<1-year
post-fire), old, unburned (≥10 years post-fire), and woodland habitat on
the landscape predicted species and functional richness. Species richness
also increased with the degree of edge contrast between patches of varying
fire age, while functional dispersion increased with the degree of patch
shape complexity. Lower than expected levels of functional richness
suggest that habitat filtering is occurring, resulting in functional
redundancy across our study sites. We demonstrate that evaluating
functional diversity and redundancy is an important component of
conservation planning as they may contribute to previously reported fire
resilience. Our findings suggest that it is the type and configuration,
rather than the diversity, of fire patches on the landscape that promote
avian diversity and conserve ecological functions. A management approach
is needed that includes significant coverage of adjacent newly-burned and
older, unburned savanna habitat; the latter, in particular, is
inadequately represented under current burning practices.