Wp��yw metody sadzenia na wzrost i jako���� hodowlan�� jod��y pospolitej (Abies alba Mill.) w Bieszczadach

Successful tree regeneration is a key process in ensuring forest sustainability and one of the most crucial investments made in silviculture. In the case of silver fir stands, optimum growth performance and stand health are strictly linked to a diverse vertical structure. This structure is usually achieved by natural regeneration and more close���to���nature, complex silvicultural systems. However, there are also stands where silver fir is missing for various historical reasons, and its restoration by artificial regeneration is required. We present results of the application of two planting methods in the Bieszczady Mountains (SE Poland) to convert pure grey alder stands into silver fir dominated mixed stands. Since 2001 in the Cisna Forest District, where a traditional row planting method is often used, a novel, group planting method (which is similar to the oak cluster planting) has also been applied: i) to reduce damage caused by deer, ii) to facilitate weed control, and iii) to promote natural regeneration of additional tree species among groups. We established a grid of 18 sample plots (each plot consisting of 4 groups of 17 seedlings in each) in three circa 20 year���old silver fir stands, as well as 15 plots (15 rows of 16 seedlings in each) representing one traditional stand (row method) in close proximity. For each tree (silver fir or admixed species) we determined the diameter at breast height, the total height and crown base height. We also assessed the silvicultural quality based on the current health status (including fungi and deer damage), as well as crown shape in the vertical and horizontal profile. To quantify the differences in growth performance we used a linear mixed���effects model approach, available in the R Statistics package (nlme). We found that height and diameter growth were higher and more uniform for the row method, but there were no statistical differences in the height of living crown base or tree slenderness. The silvicultural quality was only slightly better when using the row method. The tree species diversity (the number of admixed tree species present and their abundance) was significantly higher in stands regenerated using the group planting method. Therefore, we conclude that the group planting method could be recommended for tree species conversion on eutrophic sites, because it is likely to decrease establishment costs and creates a more diverse tree species composition and vertical structure, although it may lead to slower growth rate of silver fir up to 20 years. Due to this response, we expect higher resilience of such forest stands to the future biotic and abiotic disturbances under observed environmental changes.
Sylwan 165 (7): 542-553