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This study concerned 26 forest stands with Douglas fir situated in Lower Silesia, Great Poland, Pomerania, Warmia and Masuria. Each stand was represented by 24 trees. From each tree an increment core was taken by Pressler’s borer. The principal components analysis showed that the first three principal components accounted for 73% of the variation of chronologies in total. The first principal component was the most convergent with the mean air temperature curve for January–March, the second with the total precipitation for June–August, and the third with the mean temperature for June–August. The first principal component always integrated the chronologies and decided on a similar rhythm of changes in the tree-ring widths. The annual variation of tree-ring widths was also affected by precipitation in summer (June–August), but this differentiated the chronologies. This was reflected by the dispersion of chronologies in respect to the eigenvectors of the second principal component. The third principal component also differentiated the chronologies. Separate groups were formed by the most eastern and the most western localities of the territory under investigations. Thus the Douglas fir growth reactions were mainly affected by the thermal and pluvial conditions of summer and, to a lesser, degree by the thermal conditions of winter. On the basis of these results it was possible to distinguish the dendroclimatically homogeneous regions in western and northern Poland.
This paper discusses the results of analyses of the influence of temperature and rainfall on the width of tree-rings formed by the Douglas fir (Pseudotsuga menziesii Franco) in the years 1930-1997. The researchers selected six tree stands in the area of the Sudety Mountains. They determined that the size of the radial increments of the Douglas fir was significantly influenced by the temperatures of cold part of the year, before the vegetation season, and by those of the summer. Thermal conditions determined mainly the similarity of the rhythm of variability of tree-ring sizes. In addition, rainfall occurring in winter and during the vegetation season had Lin important, though less significant, impact on the formation of the annual increment. The influence of rainfall during the vegetation season was smaller in the case of trees from the sites located at higher altitudes and in the western part of the Sudety, which is abundant in rainfall. The spatial diversity of rainfall in the area of the Sudety was, probably, the most fundamental factor which caused the variability of the degree of similarity of the incremental rhythm of the trees from particular sites. Despite this fact, however, the Sudety Mountains can be considered as a dendrochronologia И у homogenous region for the Douglas fir.
The objective of the study was to determine the quantitative and valuable potential of wood resources of black locust (Robinia pseudoacacia) and Douglas fir (Pseudotsuga menziesii) in individual regional directorates of the State Forests (RDSFs) in Poland. We used data from the State Forests Information System database (values for the end of 2014) to determine the amount of the resources of the analysed species in forests under the State Forests management. The monetary value of black locust and Douglas fir resources was determined using both the indicator method and on the basis of sales prices of individual assortments. The occurrence, and hence the resources of black locust and Douglas fir in our country are characterized by considerable spatial diversity. Generally speaking, studied tree species are of minor importance in Polish forests as far as area and volume are concerned, but both species can the most often and in the large abundance be found in the western and northern Poland. The average sale price of wood of the tested species varied a lot in individual regional directorates of the State Forests (fig.). In the case of black locust the average sale price ranged from 99 PLN/m³ in RDSF Szczecinek to 151 PLN/m³ in RDSF Krakow, while for Douglas fir the values from 59 PLN/m³ in RDSF Łódź to 277 PLN/m³ in RDSF Katowice were obtained. The total value of black locust timber resources was assessed by the sale price method at PLN 262.4 million, and by the indicator method at PLN 186.4 million. In the case of Douglas fir timber, these values were much higher and amounted to PLN 375.0 and 309.2 million, respectively. The highest value of the studied species stands was noted in the RDSF with the largest amount of their resources.
The aim of study was to characterize Douglas fir (Pseudotsuga menziesii (Mirb.) Franco) commercial stands and their influence on the forest floor plant communities. Study plots were performed in different regions of the Czech Republic. In total 44 plots were arranged in older Douglas fir stands with well developed forest floor vegetation. For the comparison, the study plots were also established in Norway spruce and broad−leaved tree species (beech, linden, oak) stands. Compared to other studied species, the main effect of Douglas fir on plants was noted in higher share of nitrophilous species.
Douglas−fir is the most important introduced forest tree species in Poland. It is included into the frame of the breeding program that needs to test the selected objects. In the described trial the families of 14 plus trees are being tested. They are half−sib families from the open pollination. The significant differences between the families were stated in case of the diameter at the breast height and the height. The evaluation of the families being tested was carried out.
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Rozmnażanie wegetatywne daglezji zielonej

84%
Sylwan
|
1996
|
tom 140
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nr 02
25-37
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