Invertebrate Diversity under Artificial Cover in Relation to Boreal Forest Habitat Characteristics

Abstract

We investigated invertebrate diversity in boreal forests using an experimental design that consisted of counting soil invertebrates under artificial cover. The aim was to assess the utility of using soil invertebrate diversity as a measure of ecosystem health. The study area was grouped into five habitats: upland hardwood, lowland hardwood, conifer, shrub, and conifergrass. Simpson’s and Shannon’s indices of invertebrate diversity were negatively correlated with percent herbaceous cover. Number of recognizable taxonomic units (RTU richness) was negatively correlated with percent litter cover. The number of individual invertebrates was positively correlated with soil moisture and negatively correlated with percent conifer cover. Invertebrate diversity varied among habitat types, with conifer forests (spruce, fir, pine) having the highest diversity and regenerating conifer-grass forests having the lowest diversity, suggesting that successional stages affect diversity. The most productive sites, upland and lowland hardwood habitats, had the highest abundance of soil invertebrates, although intermediate diversity compared to the other five habitats. The results are consistent with the view that diversity increases and then decreases with productivity and disturbance over succession (ca. 50-100 yr). Hence, maintenance of soil invertebrate diversity in managed boreal forests requires the provision of a varied landscape with a mosaic of disturbance regimes.