Rethinking species selection for restoration of arid shrublands

Restoration is playing an increasingly important role in ecology as natural habitats become scarcer and chances to restore ecosystems damaged by human activities are more common. However, restoration of degraded Mediterranean arid ecosystems is hampered by drought and poor soils, which cause many establishment failures. To compare how species belonging to different successional stages establish in a very stressful site, we carried out a field experiment with 14 tree and shrub species differing in functional traits. After three growing seasons, mid-successional shrubs Such as the leafless Ephedra fragilis and the C-4 Salsola oppositifolia, or green-stemmed legumes like Coronilla juncea, Genisla umbellat, and Retama sphaerocarpa, showed survival rates up to 93%, while late-successional species like Tetraclinis articulata, Pinus halepensis, Olea europaea, and Pistacia lentiscus, frequently used and recommended in regular restoration projects, hardly reached 55%. We found that survival was highest for legumes, followed by leafless species, and C4 shrubs, traits that are believed to maximize resource uptake in cleared and infertile areas while reducing water losses. Thus, selection of mid-successional species having such traits should be considered for successful restoration. These species Would increase the Success of restoration programs, but also would increase soil fertility, reduce soil erosion processes, arid eventually facilitate establishment of other species, therefore accelerating secondary succession. We suggest a new approach for the restoration for arid shrublands in which species are carefully selected based on traits that best suit the environmental conditions. (c) 2009 Gesellschaft fur Okologie. Published by Elsevier GmbH. All rights reserved.