Successionary stages of formerly cultivated grassland in northern Norway, abandoned for 10, 20 and 35 years

The effect of abandonment on traditionally cultivated grassland formerly sown with Phleum pratense and Poa pratensis was studied in terms of phytosociology, species composition, soil properties and regrowth of shrubs and trees. The investigation site is a typical fisher-peasant farm in the suboceanic fjord region of northern Norway. All farming activity was terminated in 1983. Percentual species cover, chemical (P-AL, K-AL, KHNO₃, Mg-AL, Ca-AL and pH) and physical (soil type, volume weight a.o.) registrations were carried out in 1993/94 in permanent plots on a chronosequence of 10, 20 and 35 years of abandonment. A TWINSPAN-classification revealed a successional trend in five distinct stages from an open herb-rich meadow community through a Deschampsia cespitosa -dominated community towards heath-formation. According to the Central-European phytosociological system, the youngest meadows belong to the Molinio-Arrhenatheretea class. They have elements suggesting that they may be ranged under the order Alchemillo-Deschampsietalia and the alliance of Equiseto-Galion borealis, while parts of the oldest stage seem to be close to the Corno-Betuletum myrtilletosum subassociation of Vaccinio-Piceetalia. The ecological variation between the age stages was investigated by unconstrained and constrained ordination (CCA, DCCA, partial DCCA, hybrid CCA) and by multiple significance testing (Student-Newman-Keuls test in SAS). There is a significant successional trend towards heath birch woodland and a strong nutrient gradient represented by P-AL and Ca-AL acting together and decreasing with age, while K-AL is increasing.