Declining resilience of ecosystem functions under biodiversity loss

Abstract

The composition of species communities is changing rapidly through drivers such as habitat loss and climate change, with potentially serious consequences for the resilience of ecosystem functions on which humans depend. To assess such changes in resilience, we analyse trends in the frequency of species in Great Britain that provide key ecosystem functions--specifically decomposition, carbon sequestration, pollination, pest control and cultural values. For 4,424 species over four decades, there have been significant net declines among animal species that provide pollination, pest control and cultural values. Groups providing decomposition and carbon sequestration remain relatively stable, as fewer species are in decline and these are offset by large numbers of new arrivals into Great Britain. While there is general concern about degradation of a wide range of ecosystem functions, our results suggest actions should focus on particular functions for which there is evidence of substantial erosion of their resilience.

Figure 1. Trends in species grouped by ecosystem function.

Shown are the proportion of species in different functional groupings showing significant changes in frequency of occurrence in Great Britain between 1970 and 2010. Total sample sizes for respective rows are as follows: n=2,276; 590; 2,615; 95; 1,447; 720.

Figure 2. Net balance of species trends across ecosystem functions.

Shown are the log ratio of numbers of increasing versus decreasing species in different functional groups. The different bars indicate different significance levels for individual species trends. A positive ratio indicates more species in a given functional group are increasing. Differences in the balance of increasing versus decreasing species is assessed using an exact binomial test for all trends or a proportion test for significant trends. Asterisks indicate significantly different proportions (*P<0.05; ***P<0.001).

Figure 3. Balance of declining species versus new arrivals grouped by ecosystem function.

Shown are numbers of species with declines in frequency of occurrence in Great Britain between 1970 and 2010 (at P<0.05; black bars) versus the number of new species arriving into Great Britain since 1970 (grey bars). Asterisks indicate significantly different proportions using an exact binomial test (***P<0.001).