Site index curves for Norway spruce plantations on farmland with different soil types

Johansson. T. 1995. Site index curves for Norway spruce plantations on farmland with different soil types. Studici Forestulia S~lecicu 198. 19 pp. ISSN 0039-3150, ISBN 91-576-5089-6. Growth data were collected from 157 Norway spruce (Picea abies (L.) Karst.) stands planted on farmland in Sweden. The stands ranged in latitude from 55'N to 66'N. The mean age of the stands was 41 years (range, 25-91), and the mean stand density was 1640 stems ha-' (range, 400-3 722). The mean diameter at breast height (on bark) was 25 cm (range, 12-48). Classified soil types from northern Sweden were united into five groups: coarse sand (n= lo), the fine sand and silt group (14) till clay (12), sandy till (6) and fine sandysilty ti11 (6). Those from southern Sweden (lat. 55-61"N) were grouped as follows: coarse sand (n= 14), the fine sand and silt group (7), the light and medium clay group (16), heavy clay ( l l ) , till clay (13), sandy ti11 (16), fine sandy-silty till (24) and peat (6). As there was only one stand growing on soils in the light and medium clay group, and one stand growing on peat soils in northern Sweden, growth curves for these stands are not presented. Soil samples from 74 stands, 46 in northern and 28 in southern Sweden, were analysed to determine soil type, pH and content of P, Ca, K and N; dry matter content and ignition loss. The dominant height of spruces growing north of lat. 62'N was 3 m and 5 m less than that of more southerly trees at age 50 and 90 years, respectively. The dominant height of the trees varied with soil type. At age 50 years in northern Sweden, the tallest spruces grew on sandy till soils (20.3 m) and the shortest (15.2 m) on fine sandy-silty till soils. At age 50 years in southern Sweden, spruces tended to be tallest on till clay soils (25.2 m), and shortest on soils in the fine sand and silt group (21.7 m) and on peat soils (21.6 m). Survival in young spruce plantations was lower on heavy clay soils than on other soil types. Seedling height 5 years after planting was lowest on heavy clay soils.