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Biodiversity indices are widely used to summarise changes in the
distribution and abundance of multiple species and measure progress
towards management targets. However, the sensitivity of biodiversity
indices to the data, landscape classification and conservation values
underpinning them are rarely interrogated. There are limited studies to
help scientists and land managers use biodiversity indices in the presence
of fire and vegetation succession. The geometric mean of species’ relative
abundance or occurrence (G) is a biodiversity index that can be used to
determine the mix of post-fire vegetation that maximizes biodiversity. We
explored the sensitivity of G to i) type of biodiversity data, ii)
representation of ecosystem states, iii) expression of conservation values
and iv) uncertainty in species’ response to landscape structure. Our case
study is an area of fire-prone woodland in southern Australia where G is
used in fire management planning. We analysed three data sets to determine
the fire responses of 170 bird, mammal and reptile species. G and fire
management targets were sensitive to the species included in the analysis.
The optimal mix of vegetation successional states for threatened birds was
more narrowly defined than the optimal mix for all species combined. G was
less sensitive to successional classification (i.e. number of states);
although classifications of increasing complexity provided additional
insights into desirable levels of heterogeneity. Weighting species by
conservation status or endemism influenced the mix of vegetation states
that maximized biodiversity. When a higher value was placed on threatened
species the importance of late successional vegetation was emphasized.
Representing variation in individual species’ response to vegetation
structure made it clearer when a decrease in G was likely to reflect a
significant reduction in species occurrences. Synthesis and applications.
Data, models and conservation values can be combined using biodiversity
indices to make robust environmental decisions. Combining different types
of biodiversity data using composite indices, such as the geometric mean,
can improve the coverage and relevance of biodiversity indices. We
recommend that evaluation of biodiversity indices for fire management
verify how index assumptions align with management objectives, consider
the relative merits of different types of biodiversity data, test
sensitivity of ecosystem s...
201 views reported since publication in 2018.