Not even wrong: The spurious link between biodiversity and ecosystem functioning

TL;DR

This paper critically examines the methods used to link biodiversity with ecosystem functioning, revealing fundamental flaws and proposing an alternative metric to better estimate biodiversity effects, suggesting previous studies likely overestimated positive impacts.

Contribution

It demonstrates that existing statistical decompositions are flawed due to naive null expectations and nonlinearity, and introduces a new metric for more accurate biodiversity effect estimation.

Findings

Existing methods overestimate biodiversity effects due to flawed null models.

Nonlinear relationships in data invalidate traditional partitioning schemes.

Proposes an alternative metric for more accurate biodiversity impact assessment.

Abstract

Resolving the relationship between biodiversity and ecosystem functioning has been one of the central goals of modern ecology. Early debates about the relationship were finally resolved with the advent of a statistical partitioning scheme that decomposed the biodiversity effect into a "selection" effect and a "complementarity" effect. We prove that both the biodiversity effect and its statistical decomposition into selection and complementarity are fundamentally flawed because these methods use a na\"ive null expectation based on neutrality, likely leading to an overestimate of the net biodiversity effect, and they fail to account for the nonlinear abundance-ecosystem functioning relationships observed in nature. Furthermore, under such nonlinearity no statistical scheme can be devised to partition the biodiversity effects. We also present an alternative metric providing a more reasonable estimate of biodiversity effect. Our results suggest that all studies conducted since the early 1990s likely overestimated the positive effects of biodiversity on ecosystem functioning.