Carbon and nitrogen in soil and vegetation at sites differing in successional age

We studied vegetation and soil development during primary succession in an inland drift sand area in the Netherlands. We compared five sites at which primary succession had started at different moments in the past, respective ly 0, 10, 43 and 121 years ago, and a site at which succession had not yet started. In the three younger sites the vegetation was herbaceous, whereas in the two older sites a pine forest had formed. Forest formation was accom panied by the development of an FH-layer in the soil, an increase in the am ount of soil organic matter, and an increase in nitrogen mineralisation rat e from 1.9 to 18 g N m(-2) yr(-1). Soil moisture content also increased, wh ereas pH showed a steady decrease with site age. The vegetation changed fro m a herbaceous vegetation dominated by mosses and lichens and the grass spe cies Corynephorus canescens and Festuca ovina towards a pine forest with an understorey vegetation dominated by Deschampsia flexuosa and, at the oldes t site, with dwarf shrubs Empetrum nigrum and Vaccinium myrtillus. At the s ame time the total amounts of carbon and nitrogen of the ecosystem increase d, with a relatively stronger increase of the carbon pool. The establishmen t of trees during succession greatly affects the dynamics of the ecosystem, especially its carbon dynamics.