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Genetic variability of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies L. Karst.) natural regeneration compared with their maternal stands

(Instytut Badawczy Leśnictwa, 2014-03) Nowakowska, Justyna Anna; Zachara, Tadeusz; Konecka, Agata; Instytut Badawczy Leśnictwa, Zakład Hodowli Lasu i Genetyki Drzew Leśnych, Sękocin Stary

The genetic variability and biodiversity of tree populations ensures the stability and sustainability of forest ecosystems. New research tools based on molecular DNA markers enable precise characterization of forest genetic resources, i.e. detection of different allele frequencies in mature trees and progeny populations. The paper describes the genetic structure of mature stands of Scots pine (Pinus sylvestris L.) in Oława Forest District, and Norway spruce (Picea abies L. Karst.) in Jawor Forest District and stands of their respective progeny. In the Scots pine stand, there was a slight increase (0.6%) in heterozygosity level and alarger increase (4.9%) in the inbreeding coefficient of progeny trees. In the Norway spruce stand, despite a small reduction (0.9%) in heterozygosity, a similar increase (4.6%) in the inbreeding coefficient of progeny was revealed. In both stands, allele richness and the partition probability of basic clustering were high. Both pine and spruce adults and progeny trees were characterized by high levels of genetic similarity (96% and 79% respectively). Gene flow between the mature and progeny populations was high (Nm > 1) for both Scots pine and Norway spruce. Conservation of the gene pool within forest tree stands requires an increase in the proportion of natural regeneration. To estimate the extent to which genes are transmitted between adult trees and their progeny more studies are needed, especially taking into account the influence of silviculture measures, like selective tree cutting, on the genetic variability of the younger generation. These results confirm that the gene pool was conserved when transmitted between the stands studied, as well as highlighting the usefulness of such a study for the silvicultural purposes.

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The influence of different thinning methods on dominance coefficients of future crop trees in even-aged Scots pine stands

(Instytut Badawczy Leśnictwa, 2014-03) Zachara, Tadeusz; Instytut Badawczy Leśnictwa, Zakład Hodowli Lasu i Genetyki Drzew Leśnych, Sękocin Stary

The research aim was to evaluate the influence of different thinning methods on future crop tree growth. Investigations were conducted on permanent Scots-pine experimental plots, established in 1960s and 1970s in Kozienice, Łąck, Parciaki and Janów Lubelski Forest Districts. To assess the response to thinning of future crop trees, their dominance coefficients were used. These are defined as quotients for each given future crop tree diameter and average stand diameter (WP1), the average dominant layer diameter (WP2) and the average diameter of 100 thickest trees per hectare (WP3). The difference between each coefficient value at the beginning and at the end of the measurement period was used as a measure of the thinning effect. On Kozienice, Łąck and Parciaki plots the differences between treatments were significant, especially in the period after first thinning. The increase of WP3 coefficient occurred in a case of strong thinning – TS1 and TS2. On plot Parciaki also the moderate thinning TU1 and TU2 had a significant influence on change of this coefficient. On plot Janów Lubelski the influence of treatment has not been stated in the first 5-year period but in the next one. Analyses of changes in the dominance coefficients confirmed the hypothesis that the WP3 coefficient is very useful as it is the most stable indicator of future crop-tree position in a stand. On Kozienice, Łąck and Parciaki plots the significant differences between treatments were stated, especially in the period after first thinning. The influence of thinning treatment on the plot Janów Lubelski was not considered for the first 5-year period but in the next one. All reactions to thinning were slower on this plot, possibly because of the relatively poor site conditions. This was a long-term effect. The results obtained suggest that very intense thinning of Scots pine stands should only be implemented under a restricted set of conditions – in healthy, not neglected, forest stands. Classical moderately-selective thinning is preferable to intense thinning and is the most convenient option for pine stands.

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