| Forest is a important natural resource for human survival. A large number of deteriorated forests appeared with the increase in the number of afforestation area as well as management and protection not in a timely manner. Therefore, a comprehensive investigation of deteriorated forests in the low mountain area of Beijing was necessary. This paper’s research purpose is providing a theoretical basis for the transformation of deteriorated forests and promoting stand quality by selecting67deteriorated forests plots with sampling method and dividing the type of deteriorated forests and constructing assess index system and studying the transformation techniques of deteriorated forests. The main study conclusions as follows:(1) Vegetation structure showed varying degrees of defective conditions In Beijing low mountain area.The Chinese pine forests, platycladus orientalis forests, locust forest, poplar plantation, oak woodland and shrubbery, etc. are the main community types. And the plots of density, volume, and understory vegetation survey showed that a substantial proportion of stand species is relatively homogeneous, and there is no law at all in understory vegetation distribution. The diversity in species and evenness changed largely, and different types of communities showed different defective conditions.(2) The classification of deteriorated forests in Beijing low mountain areas.The deteriorated forests in Beijing’s low mountain area could be divided into the dense stands, open forests, over mature forests and non-dominate spices forests, basing on forest survey and analysis. Chinese pine dense forests’density was1017-4844/hm2, platycladus orientalis dense forests was2000/hm2. Most of open forests were new plantation without formation of crown closure. Chinese pine open forests’density was200/hm2, platycladus orientalis open forests was700/hm2. The locust and poplar forests were the most obvious over mature forests and the dying wood ratio in locust forests can reach52.43%. There were no domination spices in shrubbery and were positive to the succession of forest.(3) Constructing assess index system of deteriorated forestsThe word "deteriorated forests" was defined again, so that it became more accurate and comprehensive. Combined with survey data, using the mathematical methods and experts advices,10quantitative assess index were filtered out. The assess index mainly involved ecological and site these two indicators, including the volume of the unit area, species diversity, stand density, crown density, slope, gravel content and soil thickness. Assess index system of deteriorated forests in Beijing low mountain areas was constructed using frequency analysis determine the standard of each indicator.(4) Transformation technology.for deteriorated forestsAccording to the single species structural characteristics of the low mountain area in Beijing, this test took mixed configuration of ecological forest transformation model and planted including Chinese pine, platycladus orientalis, quercus variabilis and acer mono maxim. According to lack of color-leaf trees and ineffective landscape, color-leaf trees decorative style and scenic forest transformation model were combined. So Canadian maple, Acer palmatum, norway maple were planted in. New soil base plate method used in the transformation test, nutrient status significantly improved. Transformation of soil and water conservation forest, seedling survival rate (preservation rate) in more than80%; seedlings used in the base plate in the control group not in use compared to nearly30%above the base of seedlings, the survival rate (preservation rate), growth also significantly improved in terms of quantity; increase pits new soil base method afforestation in the scenic forest transformation, except Acer palmatum survival rate of afforestation (preservation rate) was84%, other species are more than95%,It is worth to promote the deteriorated forests transformation technology of Beijing low mountain areas. |
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