Study On The Assessment And Structure Feature Of Low Function Plantation In The Low Mountain Of Beijing

Based on the second class investigation data of the tenth five-year plan in Beijing, plantation in each county and district were investigated at random and typically. According to obtaining availability data in the test, the evaluation index system and the index weight could be determined by theoretical basis of forest ecology and statistical analysis. At the same time, the low function plantation in low mountain area of Beijing were evaluated and the concept was put forward. Furthermore, the methods of normal equidistant partition method, analytic hierarchy process (AHP) and multilevel fuzzy comprehensive evaluation were applied to determine an evaluation criterion, an index weight and a membership degree, respectively. The can be achieved through by using. The aim that the low mountain area plantation were divided into four low function grades and then respectively classified is to provide a basis for the development of forest management in Beijing. The main results of this study were as follows:(1) The plant species composition differences were not only very large between different dominant tree species, but also obvious at the same forest types, due to the affects of the human disturbance, site conditions and other factors. Three main types of diameter distribution could be obtained, such as approximates normal distribution, approximate anti-"J" distribution, and multimodal or unimodal distribution. Tree height distributions mainly have two types which were approximate normal distribution and unimodal or multimodal curve distribution. Compared with tree and shrub layers, the richness index of herbaceous layer was highest in all plots. For diversity index, the diversity variation of tree layer was greater than the other two layers, but the herbaceous layer had the highest diversity index. Tree layer had the highest variation about evenness index.(2) An index system was constructed by a target indicator, four guidelines indicators and14indicators. Indicators were divided into qualitative and quantitative indicators. Qualitative indicators were based on the determination of the classification, given the score, and normal isometric analysis was used to divide quantitative indicators into a quartern. At last, Beijing inefficient plantation was divided into four grades according to indicators and standards.(3) The total order of each index weight from inefficient planted forests evaluation wasAP=(0.09560.04780.01130.02910.04120.02770.02160.01250.13930.27850.13360.03150.07180.0586).(4) Three-level low function plantations were the most and up to40.7%in all plots. Two-level low function plantations, four-level low function plantations and one-level low function plantations was orderly29.6,18.5and11.1%of total plots. (5) The results of the low function plantations’grade classification were as follows:One-level low function plantations:canopy density was from0.8to0.9, stand density was too dense, soil thickness was more than50cm, stand structure was poor, overstocked stand density led to more deadwood, dying, dead and drying trees. Understory species diversity was single, mild anthropogenic interference. Such forest health cut should be made for deadwood in order to avoid fire, be also cut the thick, dead or dying stand, thinning appropriate in order to ensure the reasonable density.Two-level low function plantations:average canopy density was from0.4to0.5, stand density was sparse, and soil thickness was from40to50cm. This planted forest sample belonged to matching species with the site, caused by the poor development and low productivity. Such forest should be taken banding or block cutting transformation method, replanting the species can adapt to the climate and soil conditions.Three-level low function plantations:average canopy density was0.4, stand density or sparse, soil thickness between20-40cm, stand structure was poor, disease and rot were more severe within the forest, and species diversity of understory was more singleness by moderate human disturbance. The transformation method to this inefficient planted forest was intermediate cutting, replanting and afforestation at understory. Meanwhile, the ban was managed to prohibit factitious negative interference.Four-level low function plantations:Canopy density was less than0.3. The sparse stand density and soil thickness were less than20cm. The worse of stand structure, disease and rot were most severe within the forest. Forest form was broken. Stand was seriously degraded. Species diversity of understory was most singleness by serious human disturbance. Banding intermediate cuttings, after-culture transform are appropriate for this inefficient planted forest. For the problem of its soil layer thinner, out-soil replanting method should be used and fostered, meanwhile, the ban should be also used to prohibit factitious negative interference.