ZLV Online

Abstrakt

Norway spruce stands decline is one of the most persistent and pressing problems in some parts of northern Moravia. The main reason of that is probably precipitation deficiency in connection with global climate changes. Species composition change is a principal measure to mitigate the stands decline. Active stand thinning is another one, though just auxiliary. Experimental series were established in young spruce stands (northern Moravia, Opava district) in 2010. One experiment (six 0.01 ha plots in total) was founded in young (10-year old) naturally regenerated stands, two more experiments (eight 0.04 ha plots in total) were founded in slightly older (14–17-year old) artificially regenerated stands. The main purpose of the experiments is to find out the possible effect of thinning on development of young spruce stands in the region affected by decline. In 2010, half of plots were thinned. After thinning, 1,000 trees per hectare (in 0.04 ha plots) and 1,500 trees per hectare (in 0.01 ha plots) remained. The equal number of “crop” trees was marked in the control plots. Diameter and height mensuration and health condition observations were conducted annually. Thinning has led to modest acceleration of diameter increment. Mean annual diameter increment in thinned treatment is about 0.3 cm higher compared to control treatment. Relative diameter growth rate is about 2–5% higher in thinned treatment. Mortality (only crop trees are considered) in thinned treatment is slightly higher compared to control one. Nonetheless, the mortality has not endangered future stand development yet. Preliminary results of the study support active thinning of young spruce stands, even in spruce decline regions.