%0 Journal Article
%T Scale-dependent effects of habitat area on species interaction networks: invasive species alter relationships
%A Sugiura Shinji
%A Taki Hisatomo
%J BMC Ecology
%D 2012
%I BioMed Central
%R 10.1186/1472-6785-12-11
%X Background The positive relationship between habitat area and species number is considered a fundamental rule in ecology. This relationship predicts that the link number of species interactions increases with habitat area, and structure is related to habitat area. Biological invasions can affect species interactions and area relationships. However, how these relationships change at different spatial scales has remained unexplored. We analysed understory plant每pollinator networks in seven temperate forest sites at 20 spatial scales (radius 120每2020 m) to clarify scale-associated relationships between forest area and plant每pollinator networks. Results The pooled data described interactions between 18 plant (including an exotic) and 89 pollinator (including an exotic) species. The total number of species and the number of interaction links between plant and pollinator species were negatively correlated with forest area, with the highest correlation coefficient at radii of 1520 and 1620 m, respectively. These results are not concordant with the pattern predicted by species每area relationships. However, when associations with exotic species were excluded, the total number of species and the number of interaction links were positively correlated with forest area (the highest correlation coefficient at a radius of 820 m). The network structure, i.e., connectance and nestedness, was also related to forest area (the highest correlation coefficients at radii of 720每820 m), when associations with exotics were excluded. In the study area, the exotic plant species Alliaria petiolata, which has invaded relatively small forest patches surrounded by agricultural fields, may have supported more native pollinator species than initially expected. Therefore, this invasive plant may have altered the original relationships between forest area and plant每pollinator networks. Conclusions Our results demonstrate scale-dependent effects of forest area on the size and structure of plant每pollinator networks. We also suggest that a single exotic plant species can impact plant每pollinator networks, even in temperate continental habitats.
%K Alliaria petiolata
%K Biological invasion
%K Forest area
%K Mutualistic networks
%K Plant每pollinator interactions
%K Species每area relationships
%U http://www.biomedcentral.com/1472-6785/12/11