Using functional traits to assess the role of hedgerow corridors as environmental filters for forest herbs

Linear habitats such as hedgerows can constitute important refuges for native flora and fauna, possibly providing connectivity between landscape elements. The effectiveness of these functions, however, depends on the ability of linear habitats to benefit a significant proportion of the local species pool and their functional attributes. This study aims to identify life-history traits that appear to either limit or facilitate survival or colonization of forest herbs in hedgerows. The distribution patterns of 47 native forest herbaceous species and their associated traits were compared in a system of hedgerows and attached forest patches of southern Quebec. Although 83% of the species surveyed in forest patches were present in hedgerows, significant differences in abundance suggest the existence of a selective pressure on forest species in linear habitats. Early spring flowering was negatively associated with hedgerows, possibly because of unfavourable microclimatic conditions. Seed dispersal phenology partly mirrors results for flowering phenology with early summer dispersal and late fall dispersal being less common in hedgerows than in forests. Slow dispersal mainly through myrmecochory was also less common in hedgerows compared to forest sites, suggesting a selective pressure on slow dispersers in linear habitats. The capacity for vegetative propagation was positively associated with hedgerows, possibly because it provides an alternative strategy to survive and expand when conditions are less favourable for sexual reproduction. Our approach highlights traits that can help determine the vulnerability of native forest species in linear habitats or their likelihood to benefit from the maintenance of wooded corridors in an inhospitable matrix.