Spatio-temporal changes of a nature protection area in the agricultural landscape of Jæren, South-West Norway
A nature protected area within agricultural landscapes is analysed based on studies of landscape metrics, vegetation and soil, as well as measurements of the water and matter balance. Landscape metrics analyses show the influences of agriculture in shaping the landscape over the past 65 years. Increased separation between intensively used agricultural land and low-productive wet fen areas is found. Both individual patches and the total area of arable land have increased in size. Changes restricted to the nature reserve are identified as to sedimentation and vegetation succession. Expansion of reed and Salix shrubs profits from nutrient fluxes from arable land and drainage canals. Plant compositions differ with regard to the complex nutrient balance which is affected by hydrologic conditions. Scenarios are drawn which indicate that extensive land use and landscape management neither prevent sedimentation processes nor reverse the successive development. We conclude that future changes in bird species composition and occurrence will have to be anticipated. Nature protection in agricultural landscapes based on structural stability must implement management measures. The authors suggest an approach including dynamic systems to support decisions within the frame of a sustainable development of changing landscapes.