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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.
This paper presents the method worked out to assess the value of growing stock in an exemplary forest district basing on the stand−level data available from the forest inventory databases. The method was designed for European beech and silver fir growing in the Polish part of the Carpathian Mountains. Sample data includes 28 stands, where quality classes of wood were assessed for 18,000 trees altogether. Beech and fir timber prices from the transactions made in 2010−2012 and harvesting/processing costs were also included in the analysis. The proposed tariff consists of calculating the growing stock value basing on taxation features of the stands, which are described in the forest management plan as well as on local wood stock prices. The local tariffs of wood stock prices for beech and fir were calculated as a set of functions, where the diameter at breast height (DBH) is the descriptive variable. The local tariff for beech with DBH in the range of 7−22.5 cm equals approximately 89.6 PLN/m³, while for DBH in the range of 22.5−50.9 cm is described by the equation: y=–0.011·DBH²+1.9539·DBH+51,305. The local tariff for fir wood with DBH in the range of 7−18 cm amounts approximately to 99 PLN/m³, while for DBH in the range of 18−54.2 cm is described by the equation: y=0.0027·DBH³–0.3555·DBH²+15.992·DBH–80.186. The initial verification of the valuation results obtained by means of this method turned out to be positive. As the next stage, the presented method should be verified for the same stands with use of several methods, e.g. quality classes of wood and calculating the value of the cut wood and calculating valuation errors.
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.
The study describes a new method of assessing the average age of the forest range with significant share of stands in the regeneration class. In proposed method, average age of stands in regeneration layer is calculated as a mean age of tree layer as well as layer of upgrowth, recruitment and saplings weighed by these layers fraction. Example of calculation of average age was performed for 7 ranges located in Kotlina Kłodzka (SW Poland) with total area of 48 653 ha. Average age of stands calculated by proposed method vary from 62 to 73 years and is lower in comparison to average age calculating according to current regulations from 5 to 14 years. Proposed method of calculation the average age of stands in shelter wood cutting system takes into account composed structure of stands in regeneration period by using age and share of all trees generation in stand.
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