Vegetation succession on the Storbreen glacier foreland, Jotunheimen, Norway: a review

Abstract

Investigations of spatial patterns, environmental gradients, directly measured changes and plant population structures in front of the Storbreen glacier, S Norway, have extended the traditional chronosequence approach to the study of primary vegetation succession. A geoecological approach has been developed which does not assume that the vegetation patterns represent a simple linear time sequence. Distribution patterns of plant species demonstrate that pioneer colonizers are replaced at various rates and by different species depending on local environmental factors, particularly altitude, aspect and microtopography. Analyses of community types and vegetation gradients indicate a 2-stage high-altitude succession which diverges from a 3-stage low-altitude succession. Measurement of environmental variables has distinguished 2 factor complexes which are important in explaining the vegetation landscape. One of these (the snow melt/exposure/moisture factor complex) is relatively independent of terrain age. Direct measurements of vegetation change over 12 yr show strong progressive succession on terrain ages of 20-50 yr and retrogression associated with disturbance on older terrain. Sampling of the size structures of species populations has identified varying patterns of behaviour; some commonality in population patterns between species suggests common roles within the succession and common patterns in response to available resources. -from Authors