Changes in structure and quality of natural forest overstorey in National park Kon Ka Kinh, Gia Lai
Keywords:
Forest structure, forest tree quality,, frequency distribution, linear mixed modelAbstract
Forest structure plays a very important role in forest ecosystem management. Analysis results show that the average diameters of stages are 14.67cm (type IIb) and 24.4cm (type IV). The variability of the growth indicators is also greater in type IV and smaller in type IIb. The mixed linear model confirms the difference in diameter and height between the two types is very significant, random effects
are negligible with diameter, but relatively important to height. The AIC results indicate that for diameter and height frequency distribution, the Lognormal distribution is best simulated. Slope of correlation line of IV forests is smaller than II forests. The length of the correlation line is also greater. In type IIb, the commercial height has the greatest effect on the tree quality, then the height and diameter. In this type of forest, direct impact is less than the indirect effect
coefficient, so the quality of forest trees is greatly influenced by other factors such as rainfall, climate, soil condition and so on. In contrast, IV forest, the direct effect coefficient is much greater than the indirect coefficient. This shows that the forest has been stable and the quality of forest trees is less influenced by outside factors. The percentage of good and average trees (A and B) of forest IV is 87.60%. While this rate of poor secondary forest IIb is 83.65%. The difference in the quality of the trees between the two states is really significant, as the p-value of the Chi-squared test is less than 0.05.
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