A meta-analysis on decomposition quantifies afterlife effects of plant diversity as a global change driver

Akira S Mori,Forest Isbell,J Hans C Cornelissen,Saori Fujii,Kei-Ichi Okada

doi:10.1038/s41467-020-18296-w

Abstract

Biodiversity loss can alter ecosystem functioning; however, it remains unclear how it alters decomposition—a critical component of biogeochemical cycles in the biosphere. Here, we provide a global-scale meta-analysis to quantify how changes in the diversity of organic matter derived from plants (i.e. litter) affect rates of decomposition. We find that the after-life effects of diversity were significant, and of substantial magnitude, in forests, grasslands, and wetlands. Changes in plant diversity could alter decomposition rates by as much as climate change is projected to alter them. Specifically, diversifying plant litter from mono- to mixed-species increases decomposition rate by 34.7% in forests worldwide, which is comparable in magnitude to the 13.6–26.4% increase in decomposition rates that is projected to occur over the next 50 years in response to climate warming. Thus, biodiversity changes cannot be solely viewed as a response to human influence, such as climate change, but could also be a non-negligible driver of future changes in biogeochemical cycles and climate feedbacks on Earth.

Highlights

Biodiversity loss can alter ecosystem functioning; it remains unclear how it alters decomposition—a critical component of biogeochemical cycles in the biosphere
Our dataset is comprehensive by covering the broad range of climatic regions and extensive in considering many possible comparisons for decomposition rate between mixed and mono-species litter in different biomes (Fig. 1a)
When we focused on leaf litter, i.e., excluding the relatively few studies with other types of plant litter such as root and twig litter, moss, and macrophytes, we found very similar results (Fig. 1b, c; p < 0.0001 for both mass loss and the constant k)

Summary

Introduction

Biodiversity loss can alter ecosystem functioning; it remains unclear how it alters decomposition—a critical component of biogeochemical cycles in the biosphere. The biodiversity loss crisis[2] has led to the foundation of many local and international frameworks including the Convention on Biological Diversity and the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services to tackle this crisis[3,4] Along with these schemes primarily aimed at halting the loss of species and conserving organisms in ecosystems, a series of evidence has accumulated for how biodiversity is fundamental to support ecosystem functions and services for humanity[1,5,6,7]. Decomposition of organic matter is a key process in which biota play a fundamental role[15] In this regard, increasing diversity in terms of plant litter species can promote the decomposition process[16,17]. While individual studies have carefully disentangled possible mechanisms within sites, there is limited synthesis of directions and effect sizes of decomposition response to diversity available to date (but see[12])

Objectives

Methods

Results