application/pdf 16494495 bytes Institut za šumarstvo info:eu-repo/semantics/article srp 1986 Todorović, Dobrivoje Zbornik radova Instituta za šumarstvo number: 26-27 startpage: 21 endpage: 44 https://unilib.phaidrabg.rs/o:7152 All rights reserved TAČNOST I EKONOMIČNOST SNIMANJA INVENTARA RAZNODOBNIH SASTOJINA NA OSNOVU UZORAKA RELASKOPSKIH KONCENTRIČNIH KRUGOVA ACCURACY AND ECONOMY OF INVENTORY OF UNEVEN-AGE STANDS, ON THE BASIS OF RELASCOPIC CONCENTRIC CIRCLE SAMPLES In the article the efficiency of relascopic concentric circle samples (abbrev. RCC sample) was studied. Selection of bigger diameter trees, usually above 30 cm, in RCC sample was proportional to tree basal area, according to B i t t e r l i c h's method (Winkelzalprobe, abbrev. WZP). The remaining thinner trees were brought into sample from the same circle, which size was proportional to the basal area of the thinnest tree of WZP point sample In the introductory part were exposed the principle of probability proportional to size point and technical advantages of application of constant, in stead of variable horizonital angle, in the case of one tree species sample, on one standing-place. In the first part (Chapter 3.) the WZP samples were analysed from the point of view of possibilities, conditions and ways of their optitmum application in evaluation of unevenage stands (selection stands). In the Chapter 3.1. was proposed a practical way of precise establishing and regulation of the size of horizontal angle, with the objective to eliminate systematic errors of the instrumet and of the whole WZP procedure. The author analyses the technical characteristics and accuracy of both relascop and prism, giving the preference to relascop, as more precise instrument. It was established in the Chapter 3.2. and very positively judged the relationship between the size and relascopic (WZP) circles and typical distributions of tree numbers, according to diameter degrees of selection stands. Also optimum sizes of the horizontal constant angle were preliminary examined, resp. basal area factors, for application in evaluation of selected stands inventory. In the Chapter 3.3. WZP procedure was studied from the point of view of the error of tree grouping in diameter degrees of 5 cm. The author has found out that this error by WZP volume sample is much smaller than by ,,classical" volume sample, taken on the same superficies for all diameter degrees. In the Chapter 3.4. the influence of borderline trees on the accuracy and economy of RCC samples was studied. It was found out that the RCC samples, compared with the ,,classical" samples of equivalent basal areas, contain a smaller number of borderline trees and that less time was needed for checking their belonging to the sample. In the Chapter 3.5. there was analysed the spacial point distribution of RCC samples - in parallel lines, which distance was bigger than the distance between two points in the line. The author con'siders that such distribution, in comparison with square one, offers a higher efficiency of the sample. In the second part of the paper (Chapters 4. and 5.) the accuracy and economy of RCC samples in evaluation of selection stands were studied. In the Chapter 4.1 it was concluded that the basal area factor 4 permits optimum application of RCC samples in the normal selection sitands. In thinned stands the basal area factor 2 gives better results. The accuracy of RCC samples by diameter degrees was studied in the Chapter 4.2. It was found out that the application of RCC samples gives very approximate evaluation, starting with diameter degree of 10 cm up to 60 cm. In the Chapter 4.3. the accuracy of RCC samples was compared with the samples from common surficies for all diameter degrees. It was proved that the RCC samples give a better accuracy in total volume evaluation, especially by trees belonging to hligher diameter degrees. The RCC samples are less precise in evaluation of the total tree number, especially by thinner trees. Also in WZP sample the accuracy in evaluation of the total tree number falls behind the volume evaluation. The author explains it by pecularity of WZP samples. In the Chapter 5 the RCC samples were compared with the samples collected on test-strips 10 m wide with regard to the economy and efficiency. The elements of higher efficiency of the RCC volume samples are: - possibility of sampling with two workers, - less expressed variabilitv.