Modeling Tree Height, Crown Diameter, Volume and Carbon in Response to Diameter at Breast Height of Schima wallichii and Catanopsis indica: A Study from Midhills, Nepal

Abstract

The study regarding correlation between diameter at breast height (DBH) and other variables like height, crown diameter, volume and carbon of the tree species of Schima wallichii and Castonopsis indica was not done yet. Thus, this research was objectively carried out to assess the correlation between DBH and different parameters particularly height, crown diameter, volume and carbon stock. The study was centered on the mid hill region where natural Schima-Castonopsis forest is abundantly found. Total 360 nested sample plots were established having 12.62 m radius for tree, 5.58 m radius for pole, 2.78 m radius for Sapling, 1.76 m radius for seedling measurement. The DBH and height were measured of these tree species in the plots. Collected data was analyzed using Pearson correlation to show the relation of different characteristics of tree and equations were examined using ANOVA and t-test. The descriptive statistics mean ± standard error (SE) of DBH was 28.65±1.25 cm, standard deviation was 19.682, minimum value was 5.2 and maximum value was 161.5 of Castonopsis indica. Similarly, mean±standard error of DBH was 22±0.96 cm, standard deviation 10.254, minimum value was 5.5 and maximum value was 54.3 of Schima wallichii. Moreover, there was positive and strong correlation between DBH and height of Castonospsis Indica with R square value 0.71 and the equation was Y=7.1075ln(X)-9.4467 whereas, Y is the height of the tree and X is DBH. This correlation between DBH and height of Schima wallichii also showed positive and strong with R square value 0.81 and the equation was Y=7.9982ln(X)-11.277. Same correlation was found between DBH and crown diameter of Castanopsis Indica having equation Y=3.4335ln(X)-6.8637 whereas Y is the crown diameter of the tree and X is DBH. Moreover, similar correlation between DBH and volume was also found. Statistically, ANOVA and t-test showed that there was significant correlation between DBH and tree characteristics like height, crown diameter and volume at 95% confidence level. This research will be useful for the decision maker and scientific community to assess the volume and carbon measuring single variable i.e. only DBH.