Plant facilitation as a tool to restore diversity and ecosystem functions

Abstract

Traditional restoration programmes have focused on conditioning plantation sites and reintroducing plant species. Nowadays, however, ecological restoration is conceived as the complete recovery of biodiversity and ecosystem performance. Here, we review the use of plantplant facilitation as a tool to restore both diversity and ecosystem functions. Facilitation is an ecological interaction between a nurse species, which is able to colonize a stressful habitat and modify the microenvironment beneath its canopy, and the beneficiary species that are not so stresstolerant and grow under the nurse. Differences in the establishment niche between the nurse and its beneficiaries imply that species sharing facilitative interactions have different functional traits, and can therefore coexist. This process increases, at the landscape scale, all taxonomic, functional and phylogenetic plant diversity. Plant diversity patterns further permeate into those of consumers and decomposers. Thus, restoration based on plantplant facilitation allows the recovery of multiple facets of diversity at several trophic levels and, eventually, the restoration of essential ecosystem functions (fertility, productivity, or decomposition). We illustrate these cascading effects in the text by means of observational surveys in natural ecosystems governed by facilitation, as well as manipulative experiments and restoration activities.