Studies On Species Diversity, Productivity And Individual Growth Of Larix Principis-rupprechtii Community In Liupan Mountain

Larix principis-rupprechtii (abbreviated name: L-p-r) belongs to the genus of Pinus, family of Pinaceae. It is endemic specie in northern China area and it is one of the species which is a good timber and good for water conservation. The vegetation is dominated by temperate coniferous forest and deciduous broadleaved forest in Liupan Mountain. For a long period of over-exploitation of biological resources, the biological diversity decreased, biological resources scarced and ecological environment degradated in the Liupan Mountain. The changes in the eco-biodiversity are strongly influence products and services supplied by nature. While a large-scale forest afforestation campaign was lanunched in the early 1970s. L-p-r, Pinus tabulaeformis and Picea carassifolia are the main tree species, of which the afforestation area of L-p-r is the largest. Through the study on the L-p-r plantation community biodiversity, productivity, growth of individual and stands, the paper intends to provide a scientific basis for the ecosystem restoration and reconstruction, the protection of biodiversity and sustainable use, and reasonable plantation in Liupan Mountain area.The main results are as follows:(1) We analyzed the diversity, productivity of three different types of L-p-r forests and their correlation. The result indicated that the diversity of L-p-r was minimum while that of deciduous broad leaved forest was higher. The richness of pure forest was about 53%-60% that of deciduous broad leaved forest, and total biomass of broad leafed mixed forest was 152.71% that of pure forest. Accompanying species was the main decisive factor to species diversity and productivity. Species diversity and productivity of accompanying species were higher than accompanying species belong to Pinus tabulaeformis. In this article, the species diversity and productivity was always manifested as power index function, and the correlativity between the species diversity and productivity presents a remarkable level. The relations between the species diversity and productivity studied in the article was inconsistent with the unimodal relationship which many scholars approved, perhaps only on the left of the unimodal relationship, i.e., in the ascending stage.(2) The soil nutrient status of three different types of L-p-r forests were analyzed. The result indicated that total nitrogen and available nitrogen contents of L-p-r mixed forest is higher than L-p-r pure forest in the surface soil, which was improved 0.08g·kg^-1,0.02 g·kg^-1 and 17.08mg·kg^-1, 13.21mg·kg^-1 individually more than L-p-r. There was no significant difference in total phosphorus and available phosphorus contents availablity in three forests. And there were largest available phosphorus and organic matter contents in L-p-r mixed forest.And the contents were 11.72g·kg^-1 and 0.49g·kg^-1. But only L-p-r-Pinus tabulaeformis-broadleaved forest had the lowest organic matter content; that was 5.98g·kg^-1. The comparison of soil at different depths of the three different forest types, organic matter, total nitrogen, total phosphorus and nitrogen availablity were higher than any other soil depths of L-p-r pure forest and broadleafed mixed forest in 0-20cm soil depth. But available phosphorus content of 20-40cm soil depth was higher than any other soil depths. The results showed that L-p-r mixed forest and L-p-r enriched most nutrient on the soil surface; organic matter, total nitrogen, available nitrogen of L-p-r mixed forest were higher than L-p-r pure forest significantly.(3) The growth conditions of 20-25a L-p-r forest in five years were estimated and the diameter, height, volume growth curves were drew. The result indicated that three curves were the best fitting with the correlativity of polynomial curve. And the equations of the three factors in five years growth as follows:DBH growth equation D= -0.0857 a²+4.4343a-44.129(R²=0.9276); Height growth equation H=0.5089 a²-21.23 a-234.9(R²=0.9866); Volume growth equation V=0.0016 a²-0.0414 a- 1.1414(R²=0.9800).(4) The diameter distribution and stand growth dynamics of the L-p-r plantation in Sa was estimated by using direct estimation.The result indicated that the volume of L-p-r forest in Sa was 374.764 m³, accumulating volume was 21.23m³, and annual growth was 4.25m³. The growth rate was 1.17 percente and the stand-growth has been increased.