Total Stem and Merchantable Volume Equations of Norway Spruce (Picea abies (L.) Karst.) Growing on Former Farmland in Sweden

An equation was constructed to estimate the stem volume of Norway spruce (Picea abies (L.) Karst.) in 145 stands growing on former farmland in Sweden (Latitude 56–63° N). The mean total age was 40 ± 13 (range 17–91) years, the mean diameter at breast height (ob) was 15 ± 4 (range 5–27) cm and the mean density was 1621 ± 902 (range 100–7600) stems ha−1. The equation which fits the data best used the diameter at breast height and total stem height as predictive variables. Merchantable volume equations for the estimation of commercial volume for any top diameter and bole length were developed. Soil types in the stands were sediments (coarse sand, fine sand and silt and heavy, medium and light clay), tills (sandy, fine sandy and silty) and peat. The standing volume was calculated; the mean was 253 ± 103 (range 26–507) m3 ha−1 with a MAI (mean annual increment) of 6.9±3.5 (range 1.3–16.7) m3 ha−1 year−1. There were statistically significant differences between MAI and coarse sand, sand and silt, light clay, peat and silty till soils. Spruce stands growing on silty tills had the lowest MAI (4.94 ± 2.27 m3 ha−1 year−1) and light clay, fine sand and silt and peat the highest (7.62 ± 4.24, 7.46 ± 3.33 and 8.67 ± 2.83 m3 ha−1 year−1)