Linear habitat corridors for the conservation of forest herbs

The conservation or restoration of connecting habitats in production landscapes could become increasingly critical as species migration is expected to accelerate in response to climate change. Whereas much research has been conducted to identify key factors in the selection of optimal habitats for reserves, there is much to be done to test similar emergent principles for habitats found in landscapes under intense management pressure. We investigated native forest herbs in a system of forest patches and hedgerow corridors of an agricultural landscape to determine habitat characteristics that could best predict hedgerow potential at sustaining native forest herbs diversity. We also compared species distribution and abundance in forest patches and hedgerows to identify functional traits that could indicate either the vulnerability of forest herbs in linear habitats or their likelihood to benefit from the maintenance of corridors. There was a positive relationship between forest herbs diversity and abundance and hedgerows’ age as well as with the amount of adjacent forest cover, but the presence of a direct connection to a forest or to other hedgerows was non-significant. Although 83% of the species surveyed in forest patches were also present in hedgerows, significant differences in abundance suggest selective pressures in linear habitats. There was a negative association between species with early spring flowering and hedgerows, possibly because of unfavorable microclimatic conditions. Slow dispersal mainly through myrmecochory was less common in hedgerows compared to forest sites. Species with vegetative propagation were positively associated with hedgerows. The fact that forest herb communities, or at least a subset of the regional pool, can reassemble in hedgerow corridors with time implies that there could be long-term benefits in maintaining and creating linear habitats where there is a pool of dispersing species. The most vulnerable ones, however, are unlikely to benefit from the connecting function.