A phytoecological study of the mire Northern Kisselbergmosen, SE. Norway. I. Introduction, flora, vegetation and ecological conditions.

Abstract

Abstract A part of the mire complex N. Kisselbergmosen, termed the special area, is subjected to a detailed investigation of hydrotopography, species distributions, and ecological conditions. Species occurrences and distributions are related to four main complex-gradients; (1) the mire expanse - mire margin gradient, (2) the nutrient gradient, (3) the gradient in depth to the water table, and (4) a peat productivity gradient. The former two are termed broad-scale, the latter fine-scale gradients. A hydrotopographical mapping was made, including establishment of a detailed map of mire features and subfeatures, and construction of a map showing the topography of the water table. Two or three synsegments and seven catchments make up the special area. Broad-scale distributions of species were mapped in a contiguous 4x4 m grid, resulting in a classification of species to nine D-groups. Six zones reflecting variation along gradients ( 1) and (2) were discerned. The concepts of mineral soil water limit and fen plant limit were discussed by reference to hydrotopography, species distributions, and chemical composition of peat along transects. Fine-scale patterns were studied by use of 800 randomly placed plots, analyzed with respect to vegetational composition and provided with measurements of depth to the water table. Fluctuations of depth to the water table in the period 1980-82 was related to climate. Particular emphasis was put on studying parameters of the cumulative distribution functions of depth to the water table; between-year variation, interdependence, and estimation from few observations. Species were classified to seven W-groups according to relationships with the water table, and five series were considered along this gradient. The vegetation was classified into 32 site-types by a reticulate division of the ecological space spanned by the four gradients. These site-types were described by use of 654 randomly and 765 subjectively selected plots. The site-types were compared to main types of other works, and successional relationships of site-types were inferred from observed transitions and ecological measurements. Mechanisms responsible for vegetational variation along the four gradients are thoroughly discussed.