Dynamics of field-layer vegetation and tree growth in young Pinus sylvestris and Picea abies stands on microsites in Swedish Lapland

摘要

Dynamics of field-layer vegetation, and the growth of planted, pure and mixed stands of Scots pine and Norway spruce in relation to microsite conditions, were studied during 31 years from planting, on a high-altitude site with a harsh climate in Swedish Lapland. Observations were made on 360 circular sample plots on a 6-ha site. Plots had a 3-m radius, and were laid out in a systematic pattern over the site. Site conditions were assessed separately for every individual plot, then related to tree survival and mortality, height and height increment of single trees, and stand volume on individual sample plots. Tree survival, height and height increment of single trees, and stand volume, were correlated with the cover of various species of field-layer vegetation, fertilisation, frost hollows, logging residues and stump occurrence at the local level of 3-m circular plots, for single-species stands and for a species mixture. Norway spruce was more sensitive to site conditions than Scots pine, as shown by clear effects of microsite conditions on height and volume growth. Some species of field-layer vegetation at the sites were also studied, with regard to their distribution in space and development over time.