Związek dokładności modelu zbieżystości z wielkością pobranej próby
Jarosław Socha , Stanisław Grabczyński , Wojciech Ochał
AbstractIn order to describe a stem form there are frequently used so called stem profile or taper models. In this paper we analyzed relationship between accuracy of linear taper model an sample size used to its development. Taper data for this study came from section measurements of 1142 trees from five over 100 years old Norway spruce stands growing in the Wisla and Ujsoly Forest Districts (tab. 1). The taper model presented in this study is based on the equations developed to estimate relative diameters (dwj) at 20 relative stem heights (j = 0,0125 h, 0,05 h, 0,10 h, …, 0,95 h). Relative diameters were estimated according to the equation (1) and were described as a function of tree dbh and height according to equation (2). Parameters of taper model (tab. 2) were estimated on the basis of random samples size coming from: 1001, 766, 517, 393, 297, 250, 200, 143, 101, 81, 49, 43, 31, 26, 19, 14, 10, 7 and 4 trees. As the results of conducted calculations 19 taper models were received. It was stated that independently on a sample size used in development of a taper models, in the case when as independent variables dbh and h were used, the error of tree volume estimation occurs between –17% and +24%. Development of local empirical equations for determination of tree form and volume based on diameter at breast height (dbh) and tree height (h) it is possible when the sample size consist at least the empirical data from 50 trees. Increase of sample size over 250 trees does not result in changes of model parameters and reduction of the tree volume determination error.
|Other language title versions||Relationship between the accuracy of a taper model and a taken sample size|
|Journal series||Acta Agraria et Silvestria series Silvestris, ISSN 0065-0927, (B 1 pkt)|
|Publication size in sheets||0.5|
|Keywords in Polish||miąższość drzew, model zbieżystości, dokładność, wielkość próby|
|Keywords in English||stem volume, taper model, accuracy, sample size|
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