Relationships between lake and land-cover features along latitudinal vegetation ecotones in arctic Fennoscandia

Abstract

Limnological and environmental data from 53 small subarctic lakes in northern Fennoscandia and their watersheds were used to examine the relationships between watershed land cover and vegetation type and the water quality. The first two components of a principal components analysis (PCA) explained 69% of the overall limnological variation in the data. PC1 ordinated lakes along pH and the ionic strength of the water, whereas PC2 reflected water transparency, temperature and concentrations of organic matter in the water and in the sediment. PC1 scores were correlated directly with percent coniferous forest in the catchments, whereas PC2 scores were found to be positively correlated with distribution of peatlands and inversely correlated with barren land. Stepwise linear regression further demonstrated that the most important catchment properties influencing individual water quality parameters were catchment land cover/ vegetation and site factors (catchment and lake dimensions); geology (rock types) was found to be surprisingly unimportant. The most distinct differentiation was discovered between the high-altitude, alkaline, cold-water lakes situated in the barren tundra and the dilute, humic lakes surrounded by forests and peatlands in lower altitudes in the south. It is assumed that global warming and associated potential poleward movement of vegetation zones may influence physical and chemical properties of these aquatic ecosystems in profound ways.