No abstract

Persistence of restored populations depends on growth, reproduction, dispersal, local adaptation, and a suitable landscape pattern to foster metapopulation dynamics. Although the negative effects of habitat fragmentation on plant population dynamics are well understood, particularly in grasslands, the population traits that control grassland restoration are less known. We reviewed the use of population traits for evaluating grassland restoration success based on 141 publications . The results demonstrated that population demography was relatively well-assessed but detailed studies providing information on key stages of the life cycle were lacking despite their importance in determining population viability. Vegetative and generative performances have been thoroughly investigated, notably the components of plant fitness, such as reproductive output, while genetic and spatial population structures were largely ignored. More work on the population effects of ecological restoration would be welcomed, particularly with a focus on population genetics. Targeted species were principally common and dominant natives, or invasive plants while rare or threatened species were poorly considered. Evaluation of ecological restoration should be conducted at different scales of ecological complexity, but so far, communities and ecosystems are over represented, and more focus should be directed towards a population approach as population traits are essential indicators of restoration success. Conceptual Implications• Evaluation of grassland restoration success should be done at different scales of ecological complexity, but so far, only few studies have employed plant population traits that are essential indicators of restoration success. • Among population traits measured, detailed demographic studies were lacking despite their importance in determining population viability. Genetic and spatial population structures were also largely ignored. • Habitat fragmentation has well-known negative consequences on plant populations' functioning. The success of restoration in enhancing metapopulation dynamics must therefore be of concern.

15Background and aims_Calcareous grasslands are local biodiversity hotspots in temperate 16 regions that suffered intensive fragmentation. Ecological restoration projects took place all 17 over Europe. Their success has traditionally been assessed using a plant community approach. 18However, population ecology can also be useful to assess restoration success and to 19 understand underlying mechanisms. 20