Nematode communities of anthropogenous birch stands in central Finland

Abstract

Abstract This study compared the nematode communities in anthropogenous birch (Betula pendula) stands of different origin with each other and with natural forests and arable soils at the same latitude in Finland and Scandinavia. Nine forest sites were investigated in central Finland: three birch stands planted ca 30 years prior to the study after the clear-cutting of spruce stands (BS), three birch stands planted ca 30 years earlier on arable soil (BF) and three natural deciduous forests (D). There were clear differences between the birch stands established after spruce forest and after arable cropping, and between these and deciduous forests, but even more between replicates of similarly managed forests. Total numbers, species diversity, and populations of most taxa and feeding groups were the lowest in BF sites. The relative proportion of bacterial feeders and omnivores was higher and that of plant feeders lower in BS than in D sites. The BS sites were relatively similar in community structure to natural deciduous forests, and BF were dissimilar to both, although one deciduous site was similar to one BF site. Non-metric multidimensional scaling ordination placed the three BS sites in one cluster, while the BF sites were clearly separated from these and from each other. Several environmental variables related to soil moisture and acidity contributed to explain the variation in community structure. A hypothesis is suggested that the presence of burrowing earthworms plays a role in regulating populations of nematodes.