Based on the discussion of relationships between thinning and wind damage, and published information, a method for estimating risk ratios of wind damage was developed. Estimations of risk-ratio for Pinus thunbergii trees and stands were de-duced from stem bending theory and coefficients characterizing wind profile, distribution of branches and optical stratification po-rosity. The results showed that if the value of constant b in the branch distribution-model equals the attenuation coefficient s in the wind profile model for a single tree crown, then the parameter H/D1.33 (height over stem diameter cubed) can be used to compare and evaluate the risk-ratio of wind damage for individual trees. The same method can be applied to stands using the coefficient of wind profile in a stand, i.e. attenuation coefficient , the coefficient from distributions of optical stratification porosity, i.e. extinction coefficient , and the parameter D1.33. The application of parameter H/D1.33 and the process of determining risk ra-tios of wind damage for stands were also given in the paper.
Three gaps with different sizes were selected in Qingyuan Experimental Station of Forest Ecology,Institute of Applied Ecology,Chinese Academy of Sciences,which located in eastern montane regions of Liaoning Province,China for observations of air temperature and soil temperature. The observations were conducted in the gaps in June 2006,2 years after the formation of the gaps. The results indicated that both air and soil temperatures at the gap center points exhibited bell-shaped curves. The maximum temperatures occurred at different time in the gaps. The appearance of the highest temperature was earlier in large gap than that in small gaps. In the night,the larger the gap was,the lower the air temperature became. However,it was just opposite in the daytime. The highest temperature was at northern points nearby the center points for gap 1 and gap 2,and their appearance time was 10: 00 and 11: 00 respectively. But the highest temperature was at the center point for gap 3,and the appearance time was 13: 00. The soil temperatures at gap center points ranked as middle gap,large gap,and small gap. The soil temperature in gap 2 was higher than that in gap 1 and gap 2. The air temperature and soil temperature were significantly positive correlation for gap 1 and gap 3 (r=0.814,P<0.01和r=0.581,P<0.05).
