The Analysis Of Structure And Growth Dynamic Of Saplings In Spruce -fir Forest In Changbai Mountain

Based on the data coming from 60 analytic trees and 70 10 m×10 m square plots of region I at Jingouling Experimental Forest Farm, Wangqing Forestry Bureau, Jilin Province, the structure and growth dynamics of saplings were studied in spruce-fir forest. Based on the methods of quantitative ecology, forest management and statistics, ground diameter distribution, the relationship between ground diameter and tree height, species structure, horizontal spatial structure, vertical spatial structure, single tree growh models and growth process models were studied, and then sapling growth simulation system was established with computer technology. The main conclusions were as follow:(1) In spruce-fir forest, the number of saplings decreased with the increasment of ground diameter. The distribution shows the shape of inverse "J". The number of saplings of spruce, fir, Korean pine and maple decreased with increasment of ground diameter, whose distribution was also inverse "J". However, the number of saplings was decreased when ground diameter increased. The Weibull distribution function was the optimal equation which express the distribution of ground diameter grades for all species and species-specific.(2) Importance value, diversity and interspecific associations of upper tree species and lower layer tree species were analyzed. According to the analysis of importance value, the upper dominant species were spruce, fir, Korean pine and lime and the lower dominant species were maple, fir, spruce, Korean pine and lime. The diversity index of tree species of upper layer was bigger than the lower. Positive interspecific association among five tree species shows that fir, spruce, Korean pine, maple, lime can steadily coexistence.(3) The horizontal spatial structure of saplings was studied through calculating the ratio of variance/mean, mean crowded index and aggregation index, index of clumping, negative binomial parameters (K) and Cassie index (CA). The results indicated that the saplings fell under the pattern of the aggregated distribution and aggregation degree increased with height. Nearest neighbor analysis showed that saplings of spruce, fir, lime and Korean pine are most likely to regenerate under the canopy of fir adult trees and are least likely to establish under lime adult trees.(4)The height class-based model of saplings was established by using the method of height class-based modeling firstly proposed by Lundqvist in uneven-aged spruce-fir forest in Northeastern China. According to the number and height increment of saplings in each height class, the number of saplings growing out of the size stratum in each height classes and mortality rate in two adjacent size classes can be calculated, and then mean mortality rate and mean annual recruitment number of all height classes also computed. Finally, the number of saplings in each height class was predicted with 5 years for an interval in the following fifty years.(5) Based on generalized linear models and mixed linear models method, recruitment probability and density, and individual tree survival and growth of understory saplings in uneven-aged spruce-fir forest in Northeastern China were studied for all species. According to the test data, most of models for simulation systems were successfully established, though recruitment probability models do not have sound precision. Recruitment probability and density grew in direct proportion to upper tree density and composition. The size of saplings and competition among saplings had a significant effect on its mortality and increment.(6) Based on 60 fir-spruce analytic trees data, applied Logistic model, Schumacher model, Richards model, Compertz model, Levakovic2 model, Levakovic3 model, Hossefld model and Allometric logarithmic model, the ground diameter, DBH, tree volume and growth process of fir and spruce were analyzed. The results showed that the optimal diameter and tree height growth model for spruce was Richards model; its optimal diameter and tree volume growth model was Compertz model. The optimal diameter and tree height growth model for fir was Logistic model; its optimal diameter and tree volume growth model and ground diameter model were separately Compertz model and Richards model.