ZLV Online

Abstract

Long-term effect of sulphur emission on the forest stands and soils in the past and high nitrogen deposition today affect stand nutrition, mainly in northern mountain ridges of CR. This contribution shows changes in phosphorus supply in long-term investigated spruce stands in the Lužické, Jizerské and Orlické Mts. During the last six years, low phosphorus concentrations were measured, often under the deficiency limit, and N/P ratio exceeding the optimal range of (6 – 12), in the spruce needless, mainly in the second needle-year class. Low phosphorus amount was stated also in mineral soil horizon. With respect to health status (crown defoliation) all the spruce stands investigated are of similar conditions, crown defoliation is ranging between 20 – 25%. Changes in P concentrations in the needles, and in N/P ratio are more significant in the spruce stands in the Jizerské and Lužické Mts. Up to date, P insufficiency is not reflected in the stand health state. N/P ratio could be suitable and fast indicator of nutrition changes and P supply. Low P concentrations and changes of N/P ratio show that optimal N/P ratio with respect to individual tree species should be revised.