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ŠUMARSKI LIST 1-2/2021 str. 33     <-- 33 -->        PDF

Polymorphic site index curves for Beech (Fagus sylvatica L.) in Central and Eastern Serbia
Polimorfne krivulje indeksa staništa europske bukve (Fagus sylvatica L.) u centralnoj i istočnoj srbiji
Branko Stajić, Živan Janjatović, Marko Kazimirović, Zvonimir Baković, Snežana Obradović
This study was mainly aimed at constructing polymorphic site index curves for beech in the central (Rudnik mountain – RU, about 15,000 ha) and eastern (Žagubica – ŽA, about 7,000 ha) part of its distribution in Serbia. To obtain suitable height-age data and evaluate the best-fit growth model we used 107 felled dominant beech trees. The Korf, Korsun and Chapman-Richards growth functions per site class were first parameterized and then mutually compared with respect to residual statistics and the significance of their parameters. They were additionally parameterized in line with empirical data on the value and age of the culmination of current annual height increment (CAIh). The obtained results indicated that the Chapman-Richards growth function showed the best results both by statistical (residuals standard error, significance of the parameters, distribution of residuals, and homoscedasticity) and by empirical criteria (the CAIh culmination time, the maximal values of the CAIh, and the attained height of trees at a certain age) of the height-age beech modelling in the analyzed regions. The obtained polymorphic site index curves which classify sites with regard to their productivity can be very helpful in planning appropriate silvicultural treatments, and for decision-making in forest management planning, forest policy and ecology and, consequently, in the sustainable management of beech forests in Serbia and some neighbouring countries with a similar forestry sector development.
Key words: height growth pattern, site index curves, beech, Serbia
As a major driver of forest resource availability, forest productivity remains a fundamental concern in forestry (Bontemps and Bouriaud 2014). From this reason, efficient silviculture, yield and growth forecasting, forest management planning and decision-making on different levels require a reliable measure of site productivity (Wanclay and Henry 1988, Palahí et al. 2004, Pretzsch 2009 etc.). The most important indicator of potential forest site productivity is the dominant height of a stand at a reference age – the site index (Monserud 1984, Skovsgaard and Vanclay 2008, Zlatanov et al. 2012, Stajić et al. 2016 etc.). This is due fact that the height (and age) of dominant trees correlates closely with the total stand volume production and is less dependent on the stand density and thinning intensity (Davis and Johnson 1987, Stamenković and Vučković 1988, Pretzsch 2009 etc.).
Determination of site index model parameters and site productivity assessment largely depends on the quality of