Fine-scale spatial patterns of forest herb distributions within hedgerows.
Snider, James *,1, de Blois, Sylvie 1, 1 McGill University, Montréal, Québec, Canada
ABSTRACT- Within fragmented agricultural landscapes, linear structures, particularly hedgerows, may provide functional connectivity between habitat patches to facilitate dispersal of individuals among populations. Forest herbs have been indicated to use hedgerows as viable habitats and even conduits for dispersal, despite their vulnerability to fragmentation and relatively restricted dispersal capabilities. Direct analysis of fine-scale spatial distributions of species within these structures is required to assess the real conservation potential of hedgerows for forest herbs. In agricultural landscape near Montréal, Canada, we investigated the spatial distributions of forest herbs within hedgerows (n=13) that were connected to forest patches. We recorded a total of 49 forest herbs, including 41 species (83%) in hedgerows, of which 15 species were present in >50% of hedgerows or occurred in 1% of hedgerow quadrats. Fisher's exact tests indicated that 11 of these 15 species (73%) occurred with greater frequency in midline quadrats than edge quadrats. These results suggest fine-scale differences in habitat suitability within hedgerow structures. Further, patterns of forest herb species richness and individual species abundances reported cases of significant fit to mathematical models of decline with distance from the forest edge. In particular, Trillium grandiflorum demonstrated disproportionate frequencies of negative trends in abundance that are consistent with spatial dependence on the adjacent forest, suggestive of underlying biological characteristics that may restrict their distributions within hedgerows. Overall, spatial patterns of forest herb distributions in hedgerows vary by species and hedgerow, suggesting that both the biology of individual species and structural characteristics of the hedgerow interact to produce the observed spatial patterns. Empirical data of this type are essential for the design of effective conservation and management strategies that are based on understanding of the relationship between habitat and landscape structure and underlying ecological processes.
Key words: landscape ecology, connectivity, corridor function, forest herbs
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