Road edge effects on litter invertebrate communities of subtropical forests
Date
2013Abstract
We assessed road edge effects on leaf-litter macroinvertebrates in laurel and pine
forests in Tenerife (Canary Islands), studying composition, abundance, richness
and diversity, and the role of environmental gradients. We sorted species to the
finest taxonomic resolution possible and used a morphospecies approach when
necessary. In all, 15,824 invertebrates were identified from 388 litter samples (from
>500 species, five major phyla and 31 orders). Alien invasive species of Oligochaeta,
Pulmonata, Isopoda, Diplopoda and Hymenoptera were frequent in both forests.
Richness, diversity and rarefaction pointed to a disturbance threshold within the
first 10 m off the road, and edge effects were steeper in laurel forest than in pine
forest. Overabundant aliens were partially responsible for highly disturbed litter
assemblages on this edge zone in both forests. Proximity to road edge caused gradients
of disturbance of forest structure. Litter moisture, rock and litter cover in
laurel forest, and grass and canopy cover in pine forest were the best predictors
of community variation. Results seemed to give some empirical support to the
intermediate disturbance hypothesis. This altered road edge zone may accumulate
regionally causing net reductions of ecosystem area and quality, impacting on its
integrity and biodiversity.