Native and adventive detritivores (Diplopoda, Isopoda and Amphipoda) in a modified landscape: influence of forest type and edge

The distribution and prevalence in New Zealand of adventive detritivores in native forest remnants, and of native detritivores in pine plantations, are not well known. We investigated whether forest type (small urban native remnants, large remote native remnants, and pine) and plot location (edge plot vs centre plot) influenced the abundance and community composition of native and adventive detritivores (Diplopoda, Isopoda, and Amphipoda) in forests of a modified landscape in the lower North Island of New Zealand. We found that a number of adventive taxa have spread throughout native forests in the region. Two species of adventive Diplopoda – Cylindroiulus britannicus (Verhoeff, 1891) and Ophyiulus pilosus (Newport, 1842) – were especially widely distributed and found at high abundance. Adventive Diplopoda were more abundant in native than in pine forests. Plot location (edge vs centre) did not affect the abundance of detritivores. An adventive Arcitalitrus sp. was the dominant Amphipoda in small native forest remnants in urban locations; it was also the only Amphipoda present in the majority of pine forests. Almost no adventive Isopoda were found. There was no effect of forest type on abundance of native Diplopoda and most native Isopoda, whereas native Amphipoda preferred large remote native forest remnants. Overall, pine forests supported as many native detritivores as native forests, confirming that pine forests contribute to preserving native biodiversity.