Local and landscape drivers of ant and carabid beetle communities during spruce forest succession

Abstract

Community composition can be determined by various factors at both local and landscape scales. We explored the question of whether ant and carabid community composition in a spruce forest is determined largely by local site conditions or by landscape factors. Both taxonomic groups were sampled in spruce forest clear-cuts using pitfall traps in five chronosequences scattered in one large forest complex. Each chronosequence contained five neighboring patches, with each plot representing one age (ranging from recent clear-cuts with no trees or young trees to old clear-cuts with mature trees). In total, 13 species of ants and 64 species of carabids were found. Shading was the principal factor that affected ant and carabid communities along the successional gradient. For both insect groups, however, the difference between chronosequences with different positions in the landscape was more important than differences between successional stages, i.e., landscape drivers appear to be more important that local ones. Species composition was more affected by the proportion of individual successional stages within 300 m around individual pitfall traps than successional stage in the immediate vicinity of the individual trap. This study indicated that in addition to local conditions near the pitfall traps, species composition was strongly affected by the availability of optimal habitat in the surrounding landscape; a greater quantity of suitable habitat in the surrounding landscape increases the probability of greater abundance and diversity of ants and carabids in both optimal and suboptimal patches.