Matrix condition mediates the effects of habitat fragmentation on species extinction risk

Juan Pablo Ramírez-Delgado,Moreno Di Marco,Miguel Arias,Xavier Corredor Llano,Chris J Johnson,Oscar Venter,Carlo Rondinini,James E M Watson

doi:10.1038/s41467-022-28270-3

Abstract

Habitat loss is the leading cause of the global decline in biodiversity, but the influence of human pressure within the matrix surrounding habitat fragments remains poorly understood. Here, we measure the relationship between fragmentation (the degree of fragmentation and the degree of patch isolation), matrix condition (measured as the extent of high human footprint levels), and the change in extinction risk of 4,426 terrestrial mammals. We find that the degree of fragmentation is strongly associated with changes in extinction risk, with higher predictive importance than life-history traits and human pressure variables. Importantly, we discover that fragmentation and the matrix condition are stronger predictors of risk than habitat loss and habitat amount. Moreover, the importance of fragmentation increases with an increasing deterioration of the matrix condition. These findings suggest that restoration of the habitat matrix may be an important conservation action for mitigating the negative effects of fragmentation on biodiversity.

Highlights

Habitat loss is the leading cause of the global decline in biodiversity, but the influence of human pressure within the matrix surrounding habitat fragments remains poorly understood
We found that the degree of fragmentation of suitable habitat had higher predictive performance than species life-history traits, human pressure variables and other environmental conditions (Fig. 2)
We found that the condition of the matrix, as defined by the extent of high human footprint values between patches of suitable habitat, strongly influenced the effects of fragmentation on extinction risk transitions of terrestrial mammals

Summary

Introduction

Habitat loss is the leading cause of the global decline in biodiversity, but the influence of human pressure within the matrix surrounding habitat fragments remains poorly understood. While some studies have challenged the assumption of the impacts of fragmentation[6,8,9,12], others have demonstrated that the effects of fragmentation are negative and stronger for local species[5,7,13,14], in the tropics[15] and at intermediate (30–60%) levels of habitat amount[16,17] Resolving this debate is critical to not just informing efforts to prioritise the protection and management of intact and fragmented landscapes with the same total amount of habitat, and to better understand the role of the areas surrounding patches of habitat, commonly referred to as ‘the matrix’, in maintaining biodiversity[10,18,19].

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Conclusion