Succession in harvestman (opiliones) communities within an abandoned sand quarry in Belgium

Abstract

Sand mining strongly alters the existing landscape, transforming an area into a mosaic of native (sand deposits) and foreign soils, strongly influencing biotic development. The method of restoration of such excavated areas is often debated: natural succession or active restoration. We investigated how natural succession shapes harvestman communities, as part of the soil-dwelling community. We sampled harvestmen over a continuous period of 14 months in 25 plots in an abandoned sand quarry in Belgium using pitfall traps. We found significant increases in harvestman activity-density, species richness and diversity with time since abandonment of the various sections of the quarry. After about 15 years, a drastic change in species composition was observed with the establishment of forest species that more strongly depend on humid conditions to complete their life cycle. Colonisation of harvestmen closely followed vegetation succession despite their limited mobility. We argue that natural succession could be a good management tool for restoring harvestman communities as well as those of other soil-dwelling invertebrates in abandoned sand quarries.