Soil macroarthropod communities in planted birch stands in comparison with natural forests in central Finland

The aim of the study was to compare the soil macroarthropod communities in anthropogenous birch stands of different origin with each other and with natural forests at the same latitude in Finland. A total of nine forest sites was investigated: three birch stands (Betula pendula) planted ca. 30 years prior to the study after clear-cutting of spruce stands ("Birch after Spruce", BS), three birch stands planted ca. 30 years earlier on arable soil that had been under normal cultivation until reforestation ("Birch after Field", BF), and three "Natural Deciduous" (D) forests. These were sampled three times in 1998, animals were extracted with large Tullgren funnels, counted per square metre, and their biomasses were weighed or estimated. Several groups were identified to species. Non-Metric Multidimensional Scaling (NMS) was used to analyse the communities of Coleoptera and Arachnida. The macroarthropod communities and biomasses were relatively similar in all study sites. Coleoptera especially did not differentiate much between different kinds of deciduous stands, while there were more differences in Arachnida. The spider communities were fairly similar to those of coniferous forests, while in Coleoptera some of the most abundant species are rare in spruce forests. All dominant species in the study sites are common members of the forest floor fauna, and differ from those of open terrain. The populations in "Birch after Field" were generally low, and their communities could be characterised as impoverished forest communities. There were considerable differences between replicates of the same kind of forest, e.g. the spider community of one deciduous site was similar to one "Birch after Field" site, while two others resembled more the "Birch after Spruce" sites. There was not much indication of increasing numbers and diversity of litter-feeding macroarthropods such as Diplopoda and Isopoda after reforestation with birch. The factors to explain the differences in community composition between different forests are discussed. (C) 2002 Elsevier Science B.V. All rights reserved.