Assessing the effects of land use on biodiversity in the world\u2019s drylands and Mediterranean environments

Diego García-Vega,Tim Newbold

doi:10.1007/s10531-019-01888-4

Abstract

Biodiversity models make an important contribution to our understanding of global biodiversity changes. The effects of different land uses vary across ecosystem types, yet most broad-scale models have failed to account for this variation. The effects of land use may be different in systems characterized by low water availability because of the unusual conditions within these systems. Drylands are expanding, currently occupying over 40% of the terrestrial land, while Mediterranean systems are highly endangered biodiversity hotspots. However, the impact of land use on biodiversity in these biomes is yet to be assessed. Using a database of local biodiversity surveys, we assess the effects of land use on biodiversity in the world’s drylands and Mediterranean ecosystems. We compare the average species richness, total abundance, species diversity, ecological dominance, endemism rates, and compositional turnover across different land uses. In drylands, there was a strong turnover in species composition in disturbed land uses compared with undisturbed natural habitat (primary vegetation), but other measures of biodiversity did not respond significantly. However, it is important to note that the sample size for drylands was very low, a gap which should be filled promptly. Mediterranean environments showed a very high sensitivity of biodiversity to land uses. In this biome, even habitat recovering after past disturbance (secondary vegetation) had substantially reduced biodiversity and altered community composition compared with primary vegetation. In an effort to maintain original biodiversity and the ecosystem functions it supports within Mediterranean biomes, conservation measures should therefore prioritize the preservation of remaining primary vegetation.

Highlights

The rate of global biodiversity loss has accelerated rapidly in the past century as the rate of human activities has accelerated (Ceballos et al 2015; Steffen et al 2015)
Our results suggest that conservation measures in Mediterranean ecosystems should prioritize the maintainenance of intact primary vegetation, which consistently supports a much larger and diverse community of species, with a greater proportion of more endemic species
This study provides new insights into the effects of land use on biodiversity, in dryland and Mediterranean environments around the world

Summary

Introduction

The rate of global biodiversity loss has accelerated rapidly in the past century as the rate of human activities has accelerated (Ceballos et al 2015; Steffen et al 2015). More than three quarters of the Earth’s ice-free land area has been modified or is under use by humans to some extent (Ellis and Ramankutty 2008). A major contributor to human land use is agricultural production, with an estimated 37% of the terrestrial surface converted to agriculture by 2015 (The World Bank 2017). Human land uses, including agricultural lands, urban areas and plantation forests, are predicted to further expand in the coming decades to meet the rising demand of a growing population (Seto et al 2011; Kröger 2014; Von Lampe et al 2014). How landscapes evolve around the world in the near future will determine the rates of biodiversity loss, and understanding the impacts of land use is central to the conservation of biodiversity

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