| A Dynamic study of forest land, as a current research focus of forestry, is what the forest resources investigation lies in. A dynamic analysis on changes of forest dynamics is beneficial to the management of forest resources, grasp the current forest distribution and trends of forest change timely, and provide scientific foundation and accurate data information for the development and planning of regional forestry and macro decision. You Yang County in Chong Qing City, as one of the typical rocky desertification in karst area in southwest in our county, has the typical characteristics of karst area, where forest land plays a decisive role in the regional urban and rural development and comprehensive reform. Tian Guan Township has an important ecological role in You Yang County, where its unique geographical location and good environment for tree growth have exerted great influence on the ecological balance of the area. Tian Guan Township, chosen as the research area and revealing its dynamic change and trends of woodland, has its own typicality and representation, which thus provides a theoretical basis on the woodland resource management, woodland structural adjustment, forest management plan and the formulation and implementation of other economic policies.This thesis, taking Tian Guan Township, You Yang Country as an instance, based on the data source of the forest type II investigation data of2002and2012and related maps, using ArcGIS9.3software as the platform, employing query statistical methods combined with spatial analysis method and land use change analysis method, has a detailed analysis of dynamic changing condition of forest in2002and2012from different angles, analyzes the correlation between Forest change and local environment factors, sums up the the characteristics of dynamic land change in this region, and finally puts forward some suggestions for sustainable forestry development, hoping to provide basic information for rational use of forest resources information in mountainous area and protection of ecological environment.Major findings are as follows:(1)in the past10years, the total area of forest land increased by851.79hm", with forest area increased by1977.05hm2and the forest coverage rate increased by31.05percentage points. As for woodland change, coniferous forest, shrub forest, broadleaf forest, sparse forest, bamboo forest are with a net increase of924.92hm2,37.57hm2,790.9hm2,18.83hm2,32.47hm2respectively, but immature forest land and barren hills wasteland decreased by969.42hm2,198.58hm2separately. Variation of types of woodland is:the broad-leaved forest (134.05)> bamboo (100.00)> mixed coniferous and broad-leaved forest (4.58)> barren hills wasteland (-0.99)> immature forest land (-0.73)> woodland (0.33)> coniferous forests (0.21)> shrub forest (0.01). The dynamic changing trend of various types of woodland is consistent with its variation.(2) From2002to2012, the transfer situation among land type in the township is:barren hills wasteland (99.77%)> immature forest land (99.18%)> woodland (96.77%)> shrub land (64.97%)> mixed coniferous and broad-leaved forest (31.69%)> broadleaved forest (17.67%)> coniferous forest (11.90%). Increase of land area in the township mainly comes from the barren hills wasteland, immature forest land and woodland roll-out.(3) In the past10years, the area and volume of dominant tree species in the township have increase, but it is found, after analyzing per hectare changes of the dominant tree species, that a negative rate of change appeared, among which per hectare change rate of the soft broad-leaved volume is-78.58%, per hectare change rate of Pinus massoniana volume is-0.61%, per hectare change rate of hardwood volume is-0.55%and the quality of forest is in decline. The main changes in age structure are in the following:the area and volume of the young forest area increased significantly, whereas, the area and volume of the middle age forest, mature forest and mature forest area reduced significantly, which means that age structure gradually develops towards the young and thus it is not reasonable. In addition, changes in forest structure are as follows:area of the protection forest increased slightly, area in the timber forest and bamboo forest increased gradually, and fuel forest and economic forest decreased, which leads to the conclusion that forest structure is not coordinate enough.(4) When the coniferous forest, broad-leaved forest, coniferous and broad-leaved mixed forest are below the elevation of1026m area, the proportion of these areas gradually increases as the elevation increased. But if the coniferous forest, broad-leaved forest, coniferous and broad-leaved mixed forest are above the elevation of1026m area, the proportion of these areas gradually decreased as the elevation increased. However, changes of shrub land in the elevation are quite on the contrary. Open woodland, mainly distributed above626m, declined with the increase of altitude; bamboo, mainly distributed below1026m elevation, also declined with the increase of altitude. Immature forest land and barren hills wasteland increased with the decrease of altitude.(5) The area percentage of the broad-leaved forest, immature forest land and barren hills wasteland decrease with the slope becoming larger, but shrub and the first three are of the opposite condition; the area of coniferous forest increased firstly but later decreased as the slope becomes larger; the change of coniferous and broad-leaved mixed forest and bamboo forest is affected mainly by human settlements, distributed mainly in the gentle slope area.(6) Deeply affected by human activities, variation of forest types in the slope factor is mainly influenced by the barren hills wasteland and immature forest. If the barren hills wasteland and immature forest have taken a large percentage in a slope, the percentage of different forest types will change dominantly. Slope factor, compared with elevation and slope factor, has a less significant effect on forest land type change. |
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