Community Characteristics And Growth Analysis Of Larix Chinensis In North Slope Of Taibai Mountain

Larix chinensis formed in the top of ancient glaciers, being one of State 2 rare protected plants, Shaanxi unique and important group of tree species in mountain building, it play an important role in preventing and controlling soil erosion, saving water and high mountain ecosystems stability, Studying the main peak of Qinling paleontology, ancient climate, permafrost and periglacial geomorphology, the development also has important scientific value. In this experiment, data analysis and research of different Larix chinensis in the age structure and size structure characteristics, and different altitudes through the optimal diameter growth model fitting of the growth law of Larix chinensis.1. In the pure-mixed ecotone of Larix chinensis,,diversity indexsof mixed forest are higher than those of pure forest of Larix chinensis .However, in the ecotone from pure forest of Larix chinensis to he forest edge, dibersity indexs have complex change. Among pure forest of Larix chinensis ,the forest edge of Larix chinensis and shrubs.Diversity indexs are highest in forest edge.2. Studying Larix chinensis age structure and size structure, dividing the investigation of 4 different types of Larix chinensis, and dividing them into three categories, normal structure, inverted "J"-type structure and the double peak curve structure. The results showed that: Larix chinensis in the size structure and age structure, in general, consistent, that is, different stands of Larix in diameter and range of age classes on the level of consistent, Lariceta bryophteta are normal structure, Lariceta herbosa and Taibai rhododendronosum (clem-entinalosum) is inverted "J"-type structure, the Laricetum rhododendronosum(cap-itatulosum) is bimodal curve structure; size structure in different stands of different but the diameter of the focus has showed some characteristics of the distribution level, Lariceta bryophteta 25% of the individuals inâ…¥level, while more than 30% of the other three are in the distribution ofâ…¡,â…¢grade, which is a double peak curve type. Laricetum rhododendronosum(cap-itatulosum) inâ…¨number of grades and the proportion of 10% of the individual distribution; different stands of different age class structure, but the age structure of the centralized distribution of grades also showed some characteristics, including Lariceta herbosa and Taibai rhododendronosum (clem- entinalosum) in the age class level concentrated in theâ…¡,â…¢level, the number ratio of more than 35%, while the Lariceta bryophteta in the age class level with the diameter distribution, concentrated in theâ…¨rating ; Laricetum rhododendrono- sum(cap- itatulosum) of age class and diameter class distribution variance, age class concentrated in theâ…¨level, while the diameter concentrated inâ…¡level, this is their growth environment, the results of r choice of response.3. For the study of the growth of Larix diameter variation, applicating five kinds of commonly used growth models to different altitudes: low elevation (2900 ~ 3100m), middle altitude (3100 ~ 3300m) and high altitude (3300 ~ 3500m), selecting the average Larix chinensis DBH growth process of the fitting optimal model, and analyze the variation of growth. The results showed that: the low elevation and the elevation of optimal model are all quadratic equations, the correlation coefficient R2 0.9955 and 0.9882, respectively, have reached a significant level; the best model of high altitude power function, the correlation coefficient R2 is 0.9953, but its not the best model of high altitude, the best theory is not really optimal, so as to 40a as the cutoff point, before the power function, and then composed with the Logistic equation for the high altitude sub-function equations of the optimal equation; low altitude and the middle elevation of the annual increment and annual average is bigger than the high altitude, respectively 0.30cm and 0.20cm; at high altitude, age and 70a around the average growth reached maximum, while the medium and low altitude as early as in high altitude, were about to reach the largest 40a.