Open AccessAlien plants have greater impact than habitat fragmentation on native insect flower visitation networks
Author(s) -
Hansen Simone,
Roets Francois,
Seymour Colleen L.,
Thébault Elisa,
Veen F.J. Frank,
Pryke James S.
Publication year - 2018
Publication title -
diversity and distributions
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.918
H-Index - 118
eISSN - 1472-4642
pISSN - 1366-9516
DOI - 10.1111/ddi.12656
Subject(s) - habitat , native plant , biodiversity , ecology , habitat fragmentation , species richness , introduced species , fragmentation (computing) , invasive species , abundance (ecology) , biology , habitat destruction , geography , grassland , ecological network , ecosystem
Aim Habitat fragmentation and alien species are among the leading causes of biodiversity loss. In an attempt to reduce the impact of forestry on natural systems, networks of natural corridors and patches of natural habitat are often maintained within the afforested matrix, yet these can be subject to degradation by invasion of non‐native species. Both habitat fragmentation and alien invasive species disrupt the complex interaction networks typical of native communities. This study examines whether an invasive plant and/or the fragmented nature of the forestry landscape influences natural flower visitation networks ( FVN s), flower–visitor abundance and richness or flower/visitor species composition. Location The species rich and diverse grasslands in the KwaZulu‐Natal Midlands, South Africa is under threat from transformation, particularly by commercial forestry plantations, restricting much of the remaining untransformed grasslands into remnant grassland patches ( RGP s). Remaining patches are under additional threat from the invasive Rubus cuneifolius Pursh (bramble). Sites were established in RGP s and in a nearby protected area ( PA ), with and without brambles present for both areas. Results Flower abundance and flower area of native plant species were greater within RGP than in PA , but only in the absence of R. cuneifolius . Flower–visitor assemblages differed between invaded and uninvaded sites and also differed between PA and RGP sites. Both areas lost specialist flower–visitor species in the presence of brambles. Network modularity was greatly reduced by the presence of bramble, indicating a reduction in complexity and organization. The structure of FVN s was otherwise unaffected by presence of bramble or being located in RGP s or the PA . Main conclusions The RPG s contribute to regional biodiversity conservation through additional compositional diversity and intact FVN s. Rubus cuneifolius reduces ecological complexity of both RGP s and PA s, however, and its removal must be prioritized to conserve FVN s.