Functional Assemblages of Macroinvertebrates in Pools and Ditches in Drained Forest Landscape

Abstract

Artificially drained commercial forests are hydrologically novel ecosystems, where the array of aquatic habitats consists of ditches and remnant pools. In general the network of ditches has been found to have longer hydroperiod, the knowledge, however, about aquatic invertebrates in this system is scarce. We examined which environmental factors are impacting the biomass and abundance of functional feeding groups. Scrapers and shredders were aggregated to ditches and gatherers to pools. Filterers’ distribution pattern suggested that the function of filtering is carried out by different taxa in pools and ditches. Ditches were rather more suitable for feeding groups that rely on autochthonous resources. Acidity was a major driver of functional community composition, for example, one of the causes for higher scraper frequency in ditches. Predators exhibited greater quantities in extensive macrophyte cover regardless of water body type. Our results suggest that the trophic organization in ditches and pools is different because habitat factors select the feeding groups directly through food resources, but also because of the environmental filter on the other biological traits of the organisms. To support complex ecosystems with several trophic levels also in commercial forests, we suggest to avoid destroying macrophyte rich pools and ditches during silvicultural management.