engleski

Biomass in degraded Holm oak (Quercus ilex L.) forests on Croatian part of Mediterranean

This paper presents the results of green wood and leaf measurement above soil level in degraded Holm oak (Quercus ilex L.) forests. The research was done and samples collected on permanent experimental plot on Brač Island. The plot measures 1 ha, the three subplots, which were separated, where measurement on vegetation were done and its principal basic structural data stated, measure 25 m2 each (5 x 5 m). Wood and leaf biomass on experimental plots was measured separately for every sprout (small tree) as weight and volume the independent estimators were the sprout diameter at 50 and 130 cm height above soil level, the sprout height and crown diameter of sprout. The wood volume in experimental forests, on the area of 25 m2 varies between 0, 094 do 0, 223 m3, the leaf volume from 0, 044 to 0, 067 m3. The volume depends on degradation stadium of Holm oak forests that is on the dimension of each unit the forest consists of, their number on area, complex and way of grouping on the area and soil quality. The important part of research also comprises, the model for quick and reliable estimation of biomass in these forest ecosystems. The general linear modelling was used for the model development. The research results show that the wood and leaf mass in degraded Holm oak forests is in medium, very strong and exceptionally strong linear dependence on sprout diameter, sprout height and crown diameter of sprout. Correlation coefficients are between 0, 480 and 0, 929. The greatest correlation coefficient has the relation of weight, that is the wood volume and sprout diameter at 50 cm height above soil level (r = 0, 929). By univariate regression analysis of biomass above soil level, in degraded Holm oak forest, can at best be estimated on the basis of sprout diameter, also the other independent variables significantly give their part to the explanation of this regression model. Multivariate regression models don’t give significantly better results than univariate, especially by sprout diameter as the best independent estimator.

biomass; degraded Holm oak forests; weight and wood volume; weight and foliage volume; sprout diameter; sprout height; crown diameter of sprout

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