关键词: 白桦, 剥皮, 干扰, 点格局分析, 二项Logistic回归模型, 风折

Abstract: [Objective] The objective of this study was to provide a scientific basis for healthy management and rational utilization of secondary forests of Betula platyphylla. [Methods] A typical debarked B. platyphylla stand was selected in the north region of the Yanshan Mountains. Spatial characteristics and relationships between wind-breakage and debarking were determined using spatial gradient analysis, point pattern analysis and a binary Logistic model. [Results] Debarking intensity reduced gradually from the outer to the inner portions of the stand,and was higher in sparse patches, flat slopes or gully bottoms than dense patches, and slopes. Debarked stems were clustered and were negatively associated with non-debarked stems at scales of 36-50 m, and there was no association at smaller spatial scales. Average heights of lower and upper borders of debarking area were 0.52 and 1.72 m respectively, and debarking occurred on the south-western or southern side of the stem. Debarked B. platyphylla usually suffered from wind-breaking 4-9 years after debarking and usually broke at lower or upper debarking point on the stem. Most debarked stems fell towards north-east with most falling azimuths ranging from 0° to 135°. There was a competing relation between recovery growth of the stem wound and decay of exposed wood. The greater the percentage of exposed stem circumference of debarked trees, the more vulnerable the debarked stem to wind breakage. A binary Logistic model could be used to depict the probability of wind-breakage of debarked trees, using percentage of exposed stem circumference as variable. [Conclusions] Debarking in B. platyphylla was characterized by multi-scale spatial characteristics and was mostly impacted by tree location, stand density, and topography. Debarked trees were clustered and were negatively associated with non-debarked stems at larger scales. Debarking tended to be more serious in the area with more debarked trees. The more the trees were damaged, the more likely they were broken by wind. Management should emphasize reducing the amount of debarked trees in more vulnerable areas of stands in the early spring. Bark should be collected after tree cutting and be utilized in appropriate products.

Key words: Betula platyphylla, debarking, disturbance, point pattern analysis, binary Logistic model, wind-breakage