Spatial variability of insect communities in a homogenous system: measuring biodiversity using Malaise trapped beetles in a Pinus radiata plantation in New Zealand

摘要

Insect communities of second rotation Pinus radiata stands in Kaingaroa forest, New Zealand, were characterized using Malaise trapped beetles. Samples were collected from the part of the adult beetle activity period previously shown to deliver bestdiscrimination of samples from New Zealand habitats. Eight trap-sites within a 14-yr-old Pinus radiata stand provide indications of community variation within this relatively homogeneous forest environment. Single trap-sites in adjacent younger (5-yr-old) and older (30-yr-old) stands provided initial intra-rotation comparison. Beetle assemblages from the 3 stand ages were unable to be discriminated using similarity or diversity indices, but were clearly distinguishable using divisive cluster analysis. Age of stands was of primary importance in distinguishing clusters, with those from the 5-yr-old stand being most dissimilar. Clustering of catches from within the 14-yr-old stand was influenced more by week of capture (temporal variation) than trap-site(spatial variation). Within the 14-yr-old stand, variation of abundance was associated with dominant detritivore species, and the extent and proximity of debris resources. Species richness was more constant, although considerable variation in component species was recorded. Trophic structure was also relatively consistent, with anomalous apparent variation possibly due to ignorance of species life histories. Successional processes were apparent within the insect samples over the rotation. The majority of the species in the beetle assemblage from the 30-yr-old stand were present at mid-rotation, but relative abundance of component species had changed. Beetle assemblages from all 3 age classes of stands were dominated by endemic detritivore species, reflecting the constant addition of woody debris within this rapid growing exotic vegetation system.