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The effect of commercial thinning in Scots pine stands on the growth of black cherry
Abstract Black cherry (Prunus serotina Ehrh.) is one of the most abundant invasive species found in Polish forests. The mass occurrence of this species in pine stands is one of the main problems of silviculture. Therefore, the paper addresses the problem of the effect of commercial thinning, which increases the access of light to the lower layers of the stand, on the annual growth of rings and the development of black cherry. The study attempted to determine the strength of the progression of the black cherry threat as expressed by increased diameter increment. It was assumed that the thickness increment of mature black cherry individuals after thinning would be significantly greater compared to the average thickness increment before thinning. Over time after the treatment, the average growth of sprouts of black cherry will decrease. Six pine stands differing in age and timing of the silvicultural treatment in the Golub–Dobrzyn Forest District (N 57°81′42″ E 50°20′19″) were analysed. A positive effect of commercial thinning on the thickness increment of black cherry was found in all the studied plots. Over time, the average increment of black cherries resulting from the clearance decreased. Conducting late thinning, in pine stands where black cherry occurs, results in an increased threat of its expansion. To limit the development of black cherry at this stage of pine stand management, two solutions are possible. The first is to abandon late thinning or reduce the intensity of the treatment, which will inhibit its rapid expansion. The second scenario is to limit the occurrence of black cherry a few years before thinning, perform thinning and introduce understorey or underplanting from native competitive tree species.
The use of attractants in reducing the occurrence of the Prunus serotina (Ehrh.)
Abstract Black cherry, which occurs in European forests, contributes to their distortion or degradation of native ecosystems. Therefore, measures are taken to reduce its occurrence. One of them is the biological method involving grazing animals. The aim of this research was to develop and identify an attractant that would increase the attractiveness of black cherry as a feeding base for deer, which would limit its occurrence. This research was carried out in Zielonka (17.10941 E 52.553975 N). In the experiment, 3-year-olds were used: Tilia cordata, Acer pseudoplatanus, A. platanoides, Fagus sylvatica and Prunus serotina. Before planting the seedlings, their height was measured. The control (K, 10 trees) consisted of trees of each species that were not sprayed with attractants. Another set of 10 trees were treated over the entire surface of the shoots with a bait mixture (MW), and the next 10 trees were sprayed with a 10% aqueous solution of NaCl. The attractant spraying was repeated six times. All damage observed was recorded. The inventoried tree damage was divided into four categories: 0%, no damage; I, 1–20% damaged trees; II, 21–50% damaged trees and III, more than 50% damaged trees. The results of the Mann–Whitney U test (p = 0.0109), at the assumed level of significance (α = 0.05), showed that slightly higher seedlings were browsed. These studies indicate the potential of using attractants as preparations influencing the palatability of the black cherry for deer. All recorded bites were classified as degree I damage. The trees were gnawed by fallow deer, 35.33% of trees were not damaged by game at all, and 64.66% of trees were damaged in degree I. In the case of sycamore maple, Norway maple and linden, the bait mixture did not increase the number of nibbled buds and leaves, while NaCl increased the attractiveness of beech and black cherry as a feeding base. Conducting further research studies on the improvement of preparations may give a chance to reduce the use of chemicals in forest protection and give the possibility of using attractants where it is impossible to use herbicides.