Minimum Area Requirements (MAR) for assemblages of mammal and bird species in global biodiversity assessments

Verboom J., Snep R.P.H., Alkemade R., Stouten J., Pouwels R., Pe’er G. & Goedhart P.

Abstract       

Habitat loss, fragmentation and degradation are significant factors in the rapid decline of biodiversity worldwide. Simple tools (models, algorithms, databases) that take these factors into account are needed to assess the impact of land-use change and policy measures on global biodiversity. In this paper we combine existing databases for the minimum viable populations of terrestrial bird and mammal species with knowledge of home range size to derive estimates of their minimum area requirements (MAR). Thereby we build a database that can serve as a starting point for assessing ecosystem integrity in global assessment scenario studies, for resulting areas of different sizes.

The approach exemplified here is one which focuses on comparing the minimum area requirements (MAR) to the remaining natural habitat area, under the simplifying assumption that under a certain threshold populations are no longer viable and the species assembly is subsequently reduced. Although the confidence intervals are large, our results suggest that many existing parks and reserves might be too small for the long-term viability of species that they are meant to preserve. The relationship between nature area and % of species meeting Minimum Area Requirements appears to be log-linear between 10 km2 and 100 000 km2 and has the form y = 23.715 *LOG10(area size) – 17.512. Applying this relationship to a global land cover dataset reveals that significant proportions of large mammal and bird species already fail to cover sufficient area to support viable populations at current state and in large areas of the globe, especially where rapid urbanisation and agricultural expansion has taken place and is anticipated to proceed.

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