Leaf area and tree increment dynamics on a fertile mixed-conifer site in southern Finland

Abstract

Ratios of volume increment to photosynthetic area were used to provide measures of growing space efficiency in Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) dominated stands on a productive site in southern Finland. Eight plots were established in a stand treatment study and three plots in nearby untreated Scots pine stands. Treatments included low thinnings, individual tree selection cuttings and untreated controls. Projected leaf area of individual trees was represented by sapwood cross-sectional area at the crown base. Ratios of volume increment to leaf area index (LAI) for stands and species, and ratios of volume increment to sapwood cross-sectional area were used to assess the relative growing space efficiency of stand components. LAI was greatest in stands dominated by Norway spruce. Strong relationships were observed between individual tree volume increment and sapwood area of both Scots pine and Norway spruce. For both species, these relationships were improved when developed separately for lower and upper crown classes.