Variation in the morphological structure of the crown of Norway spruce in North Estonian alkalised soil.

Abstract: Characterisation of tree crown structure provides critical information to assess a variety of ecological conditions for multiple purposes and applications. The aim of investigation was to elucidate the influence of the alkaline soil on the formation of the crown of Norway spruce (Picea abies (L.) Karst.). The seven sample plots (0.05ha) with 75–90-year-old spruce stands of Oxalis–Myrtillus site type were selected at different distances from a cement plant influenced over 40years by alkaline dust pollution. The studies were conducted 13years after dust pollution had practically stopped. High pH values (6.1–7.8), large concentrations of dominant dust components (Ca, Mg, K) and a lower level of N and organic matter in the upper layers of soil within about 6km from the emission source compared to the unpolluted control area 30.4km from the source (pH 3.3) were found. Disbalance in mineral composition in needles and shoots was established, deficite in N and excess in Ca and K concentrations were brought about a great differentiation in growth and biomass formation between unpolluted and polluted trees. On the most polluted area the average height of trees and living crown, the length and dry mass of shoots and needles were lower, and average life span of needles were shorter than in unpolluted area, indicating an increased defoliation rate of the crown. [Copyright &y& Elsevier]