Acta Scientiarum Polonorum
Silvarum Colendarum Ratio et Industria Lignaria

Nadleśnictwo Turek ul. Chopina 70, 62-700 TurekBackground. The work presents the evaluation of the impact of grey alder (Alnus incana (L.) Moench) on Scots pine (Pinus sylvestris L.) in dry oligotrophic habitat on a post-fire area.

Material and methods. The study was carried out on Department of Silviculture of University of Life Sciences a permanent experimental plots, which was founded in a post-fire area in the Potrzebowice Forest District (52°85’N 16°17’E). The experimental area was established in 1994 in a block of 6 replications. Five mixing trees variants were used. The following variants of mixing Scots pine and grey alder were used in the experiment: variant 1 - 100% pine (So100); variant 2 - 75% pine (So75), 25% alder (Ol25); variant 3 - 50%Pine (So50), 50% alder (Ol50); variant 4 - 25% pine (So25), 75% alder (Ol75); variant 5 - 100% alder (Ol100). Observations and biometric measurements of Scots pine, made 21 years after the after planting suggest beneficial grey alder effects on Scots pine.

Results. The average survivability of the grey alder was 15,6%, while the Scots pines 46,6%. The average height of the grey alder in the whole experiment was close to 1,4 m and the Scots pine more than 9 m. In terms of diameter at breast height (DBH), the highest values were obtained for Scots pines growing with 75% admixture of grey alder, an average of 11,13 cm. It was observed that decreasing the share of alder also caused a decrease in the average values of Scots pine DBH. The one-way analysis of variance, at the significance level of α = 0,05, showed statistically significant differences in the DBH of the Scots pine growing in different mixing with the grey alder (F = 9,779; p = 0,000352). The variant with 75% admixture of grey alder forms an independent group with the thickest pines. Variant without grey alder admixture (So100) was in an independent group with the smallest DBH, however with the highest productivity.

Conclusion. Grey alder has a positive effect on the biometric features of Scots pine. A high proportion of grey alder (50% and more) reduces the possibility of producing wood from tending operations. Prolonging the positive effect of grey alder on pine can be achieved by selecting a row form of mixing and increasing its share to 50%.