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4
86%
The stand volume is one of the forest inventory characteristic determined during the field work aimed at planning operations in the tree stands. Determining the optimal rotation age is an important decision issue in the forest management. In turn, the key factor that determines the choice of the method for determining the rotation age of the tree stands is the production target. Depending on the rotation age, a specific structure of quantity, quality and dimensions of particular timber assortments is obtained. It seems reasonable that the economic rotation age is one of the main criteria taken into account when planning forest management in tree stands or forest district. The aim of the paper is to assess the impact of growing stock on determining the rotation age of Scots pine stands in particular site index classes. We compared the tabular (i.e. based on data from yield tables) and real (i.e. based on data from the Information System of the State Forests) volume of pine stands. The analysis was based on the forest description data, the amount of the harvested timber and economic data: timber price as well as the costs of harvesting, skidding and production of assortments. The optimal economic rotation age was determined as the point of intersection of the curve describing the average and current increment of the value of Scots pine stands. The research showed that the rotation age of stands is related to the site index class and whether real or tabular results are analysed. The optimal rotation age for Scots pine tree stands is lower in the real data model from 10 to 23 years from that calculated on the basis of tabular data.
10
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Porownanie roznych tablic zasobnosci dla jodly

86%
Sylwan
|
2000
|
tom 144
|
nr 02
79-98
Statistical representative method of inventory based on stratified sampling is used for elaborate forest management plans in Poland. Strata are created according to the dominant tree species and age of stands. First stratum include stands with age from 21 to 30 years and the interval in the next strata is 10 years. Sample plot size depends on stand age and varies from 0.005 to 0.05 ha. According to the allocation pattern number of samples is proportional to age and total area of stands in a stratum. Diversification of number and size of sample plots has a profound influence of inventory precision in an age classes. The aim of the study is to analyse the accuracy of the stand volume determination on the level of age−species strata. Research was conducted based on the data obtained from periodic forest inventory in seven mountainous forest subdistricts located in the Kłodzko Basin (SW Poland). Norway spruce stands with total area of 39,935.45 ha and 6102 sample plots were chosen for analysis. Sampling fraction, mean number and volume of trees on a sample plot, coefficient of volume variability and standard error of volume were calculated for each stratum in analyzed forest subdistricts. Sample plots with size of 0.005 ha established in young stands (21−30 years) are characterized by small number of trees (4.3−7.6 in average) and the highest coefficient of volume variability (93%). Additionally, because of low age of stands, the number of plots is also small (18 on average), which influences the low precision of volume inventory in this stratum. Standard error of volume was on the mean level of 23% in the youngest age stratum and decreased with age of stands to 5% in the stands of 41−71 years and below this level in the strata with the older stands. Increasing the plot size in the youngest stratum will be effective way to improve accuracy of forest inventory in the method based on stratified sampling.
14
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Problem zagospodarowania drzewostanów jodłowych

72%
15
72%
Sylwan
|
2010
|
tom 154
|
nr 07
478-487
The paper presents assessment of the value of selected beech and fir stands by the classic method and using the value tariff in two ways. The aim of the work was to verify the suitability of the local tariff method based on the SILP forest database for the valuation of timber resources in forests. The measurements were carried out in the Beskidy Mountains (southern Poland). The reference sales value of the beech and fir stands with the growing stock from 61 to 643 m³/ha ranged from 6,307 to 102,438 PLN/ha. The average value of stands is about 45,000 PLN/ha and the standard deviation around 20,000 PLN/ha, with an average volume of 340 m³/ha and standard deviation of 140 m³/ha. The monetary value of the uneven−aged fir and beech stands calculated by the mean of the local tariff of value (method 1) was different from the values calculated either basing on the traditional method or on the method 2. However, the difference was on average 11% when it came to the previous, and about 2.2% when for the latter method. Almost 50% of the stands were valuated using the second method with an error of ±2.5%, the maximum extreme negative error being –14% and the maximum extreme positive error being +11%. As soon as the calculation process were automatised, the present method to obtain the local monetary value tariff of forest resources could become a practical tool in the process of forest resources valuation for the needs of the State Forests and as such it could replace the so−far used stand value tables.
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