Identifying reference communities in ecological restoration: the use of environmental conditions driving vegetation composition

Abstract

In restoration ecology, the reference ecosystem represents a key concept which is well defined from a theoretical point of view. In practice, however, selecting reference systems, such as reference plant communities, often lacks clear methodology. In order to facilitate this selection, we provide a framework based on ecological theory, and more precisely on relationships between vegetation and environmental factors, to identify reference plant communities. The four major steps are: (1) the delimitation of a geographical zone in which habitat types similar to restoration sites occur; (2) the identification of environmental factors structuring non-degraded plant communities within this geographical zone; (3) the comparison of the environmental factors between non-degraded and degraded sites; and (4) the selection of the non-degraded sites most similar to restoration sites in terms of environmental factors to use them as references. We concept-proved our approach by identifying reference communities using environmental factor combinations for five mountain grassland sites degraded by the construction of a high-voltage line. In a multivariate analysis of 18 non-degraded sites, we identified six major environmental factors explaining plant species compositions. A second multivariate analysis including degraded sites provided environmental distances of the 18 non-degraded to each of the degraded sites. The results demonstrated that the environmentally most similar sites were not necessarily the geographically closest ones. In conclusion, the analysis of regional plant-environment interactions provides an important tool to identify reference communities or source sites for seed transfer if not available adjacent to degraded habitats.

The effects of site preparation equal those of seeding at a dryland restoration site: 6 years of plant community development

“…When the plausible reference areas are themselves degraded (e.g. Derbecq et al 2020), a target based on the management goals for the restoration site may be warranted. When choosing a restoration target different from the surrounding lands, the forces that have degraded the surrounding lands must be identified or they will similarly impact the newly revegetated area.…”

Mountain grassland restoration using hay and brush material transfer combined with temporary wheat cover

“…Since best reference sites are not always the closest ones (Durbecq et al, 2020), we surveyed eighteen non-degraded grasslands along the new electricity line. These potential references included the donor site and were located at the same altitudinal belt as restoration sites (1000 -1400 m).…”

Seedling recruitment in mountain grassland restoration: Effects of soil preparation and grazing

“…The experiment was set up in October 2018 using a full factorial split-plot design replicated on five sites (blocks) to test the effect of previous soil preparation, grazing and its interaction on seedling recruitment (see Durbecq et al, 2020, for the position of experimental sites). Each of the five sites comprised eight plots of 16 m 2 each (4 m × 4 m) resulting in a total of 40 plots.…”