Conceptual and methodological issues in estimating the success of ecological restoration

Lilian Marchand,Bastien Castagneyrol,Juan J Jiménez,Jose M Rey Benayas,Marie-Lise Benot,Carolina Martínez-Ruiz,Josu G Alday,Renaud Jaunatre,Thierry Dutoit,Elise Buisson,Michel Mench,Didier Alard,Emmanuel Corcket,Francisco Comin

doi:10.1016/j.ecolind.2021.107362

Abstract

Ecological restoration (ER) of terrestrial ecosystems has become widespread in past decades. However, assessing its success is complex mainly due to the diversity of objectives pursued, actions undertaken but also statistical methods for treating data. We demonstrate here that, due to the heterogeneity of collected data, the success of restoration actions can be overestimated in meta-analyses. We advocate analyzing distinctly two types of actions in ER, those aiming at increasing an ecosystem attribute (e.g. species richness of a native plant species, ER+), and those aiming at decreasing it (e.g. invasive species cover, ER-). We also suggest that only one index for assessing the success of a restoration action is not enough. We propose here to complete RR (Remaining Recovery) by a novel index informing on ‘what has been restored by comparison to what should have been recovered’: the ‘Achieved Restoration’ index (AR).

Highlights

The 21st Century is witnessing widespread awareness on the need to effectively restore degraded ecosystems (Bullock et al, 2011; UNDP, 2014; Corlett, 2016)
By aggregating data from ecological restoration operations aimed at increasing the attributes of an ecosystem with those from actions aimed at decreasing them, LnRR artificially tends towards zero, which leads to underestimating the resulting RR and overestimating the potential of ecological restoration operations
We suggest completing the conventional RR approach by a novel index, the Achieved Restoration’ index (AR) index, which informs on ‘what was done by comparison to what should be done’

Summary

Introduction

The 21st Century is witnessing widespread awareness on the need to effectively restore degraded ecosystems (Bullock et al, 2011; UNDP, 2014; Corlett, 2016). Ecological restoration (ER) − the process of assisting the recovery of an ecosystem that has been degraded, damaged, or destroyed (Society for Ecological Restoration definition) - is solicited to deliver proven and scalable actions coping with the loss of biodiversity and ecosystem services (Menz et al, 2013; Possingham et al, 2015; Kaiser-Bunbury et al, 2017; Comín et al, 2018; Jones et al, 2018). The aim is to manage the multiple intermediate states defined by Suding and Gross (2006) and the possible restoration trajectories to optimize the restoration potential

Methods

Results

Conclusion