Consequences of biodiversity loss diverge from expectation due to post-extinction compensatory responses

Matthias S Thomsen,Jasmin A Godbold,Clement Garcia,Martin Solan,Stefan G Bolam,Ruth Parker

doi:10.1038/srep43695

Abstract

Consensus has been reached that global biodiversity loss impairs ecosystem functioning and the sustainability of services beneficial to humanity. However, the ecosystem consequences of extinction in natural communities are moderated by compensatory species dynamics, yet these processes are rarely accounted for in impact assessments and seldom considered in conservation programmes. Here, we use marine invertebrate communities to parameterise numerical models of sediment bioturbation – a key mediator of biogeochemical cycling – to determine whether post-extinction compensatory mechanisms alter biodiversity-ecosystem function relations following non-random extinctions. We find that compensatory dynamics lead to trajectories of sediment mixing that diverge from those without compensation, and that the form, magnitude and variance of each probabilistic distribution is highly influenced by the type of compensation and the functional composition of surviving species. Our findings indicate that the generalized biodiversity-function relation curve, as derived from multiple empirical investigations of random species loss, is unlikely to yield representative predictions for ecosystem properties in natural systems because the influence of post-extinction community dynamics are under-represented. Recognition of this problem is fundamental to management and conservation efforts, and will be necessary to ensure future plans and adaptation strategies minimize the adverse impacts of the biodiversity crisis.

Highlights

Consensus has been reached that global biodiversity loss impairs ecosystem functioning and the sustainability of services beneficial to humanity
Species extinction and the associated degradation of ecosystems are proceeding at an accelerating pace[1,2,3], but the consequences of the current decline in biodiversity for socio-ecological systems represent a critical knowledge gap for policy-makers[4]
Consensus reached from experiments that have manipulated biodiversity and measured various ecosystem functions, including primary productivity, nutrient cycling and decomposition, predict an accelerating decline in ecosystem properties with increasing biodiversity loss[5], yet it is not clear how appropriate it is to apply this general relationship at the landscape scale[6]

Summary

Introduction

Consensus has been reached that global biodiversity loss impairs ecosystem functioning and the sustainability of services beneficial to humanity. Our findings indicate that the generalized biodiversity-function relation curve, as derived from multiple empirical investigations of random species loss, is unlikely to yield representative predictions for ecosystem properties in natural systems because the influence of post-extinction community dynamics are under-represented. The role of population dynamics in moderating the consequences of extinction have received little attention[12,13,14], despite direct evidence that communities undergo fundamental shifts in the relative abundance of taxa and the dominance of species in each successive assemblage that follows an extinction event[15,16] Such community turnover resembles that of recovering post-disturbance communities[17], where a variety of compensatory interactions amongst surviving species[18] develop and offset, wholly or in part, the functional contributions made by species that have been extirpated[14]. Our objective is to establish the extent to which alternative compensatory dynamics alter biodiversity-function relationships

Objectives

Methods

Results

Conclusion