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Rola etatu jako regulatora rozmiaru uzytkowania lasu

100%
Sylwan
|
2005
|
tom 149
|
nr 06
45-54
The adopted rotation age and prescribed cut are found not to be fully respected at any stage of regulation, planning and implementation of cutting plans. As a result, timber, the main crop in forestry, is not uniform in terms of rotation age and fails the adopted criteria of crop maturity. Protective forests are not subject to management unless cut determination derives from silvicultural needs, without specifying the criteria for these needs. The level of cuts subjectively determined by quality control inspectors is not respected in forest management practice and should be recommended for use in the forests administered by the State Forests.
14
72%
For effective forest management, comprehensive information on the condition and structure of wood resources is needed, as well as a forecast of their development and the possibility of harvest cutting in the long term. The paper objectives is to present a methodology of predicting the development of wood resources and the possibility of main cutting based on the current state of the forest. Presented methodology of the forecast preparation is based on the inductive type of prediction in which future directions of changes are predicted based on past events. Such forecast finds expression of conscious human activity in actively shaping the future, while it does not seek to determine the target state of the forest, but it is assumed that shaping the state of the forest can be subject to constant evolution. The forecast of the development of wood resources in individual forest areas may be based on the data contained in the forest management plans, and these data may be compiled either for individual forest districts (or other forest units), or for groups of forest districts (e.g. for regional directorates of the State Forests, or the State Forests in total). The initial data, necessary to make forecasts, are primarily: a tabular comparison of the stands area and volume in age classes and subclasses; projected afforestation area; intensity indicators of final cutting and intermediate felling determining the harvesting intensity in relation to the size of wood resources in individual classes and age subclasses; and the expected volume of current volume increment over the adopted forecast periods. Additional data contains: approximate share of clear− and complex cutting in final felling; adopted distribution according to the age classes of the young generation after removal cuts in stands kept in complex cutting; average length of the regeneration period; and average age of stands in regeneration classes – used to determine the average age in forest areas for which a forecast is made. Presented methodology makes it possible to determine and analyse anticipated changes in area and volume in age classes, average age and average stand volume as well as possibilities of final and intermediate cutting, and the harvesting intensity in relation to the size of wood resources and the current volume increase in the adopted forecast periods.
The research concerned the implementation of tasks in the field of harvesting timber in 2008−2012 in pure pine stands aged 10−140. Numerical data from the SILP database were used for calculating the average price of timber in the intermediate harvest. The data on the volume harvested covered late cleaning, early thinning and late thinning. The assortment structure concerned the following groups of large− (WA0, WA1, WB0, WB1, WC0, WC1 and WD), medium− (S10, S11, S2A, S2B, S3A, S3B and S4) as well as small−sized (M1 and M2) assortment groups. The data on the size and value of wood assortments sold across the country concerned the year 2011 and were used to calculate the average price of wood in age subclasses according to the site quality described with site index class. Subsequently, for each site quality class polynomial equations of the trend line was determined and average timber price for each age subclass was calculated for small−, medium− and large−sized assortments. The analysis showed that S2 is the most frequently harvested assortment in the intermediate cuts in Scots pine stands, whose share depending on the site quality class is at the level of 65.7−72.7% of total harvest. The share of small−sized assortments decreases with age in all site quality classes. The opposite tendency is seen for large−sized assortments, whose share decreases with the deterioration of the site quality. Fraction of medium−sized assortments reaches its peak at the age of ca 45 in IA site index class and the shift in the peak with age is associated with the deterioration of the site quality. The higher the site quality, the higher the prices of assortments in the intermediate harvest. This trend occurs in all age subclasses.
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