| In this paper, by means of TM images, data of forest resouece secondary surveying and relief map and so on , recurring to GIS software of ArcInfo,current statuses, dynamic processes and main dominating factors and mechanisms of landscape ecology of the Nyingchi Prefecture in southeast Tibet were analyzed firstly,detailly and systematically , and landscape ecology of the prefecture was studied and programmed based on reviews of forecasting methods and results of the landscape dynamic simulations. The study was aimed to lay a foundation for further studies on landscape ecology of the southeast Tibet and to provide theoretical basic for sustainable development of forest resources of the area. This present study extended and improved research contents on landscapes at the coldest ecological environments, supplied a gap of Tibet landscape ecology, and provided basic data for landscape ecological systems of China.During the processing, following results and evolvement were gained in the paper:Firstly, landscapes of Nyingchi Prefecture of Tibet were classified,and quantitative analysis of land scape heterogeneities was conducted for the first time. It was showed through the present study that landscape ecology of the Nyingchi Prefecture could be classified into twelve landscape key elemental types at the first level, total number of patches was 17,335, average area of the patches was 446 hm~2, and three ecological space patterns namely the natural, the semi-natural and the management landscapes were formed. results of landscape heterogeneities analysis are showed that forest landscapes were the dominating landscapes of the prefecture, and the natural landscapes were kept in a comparatively good primeval state.But the degree of fragmentation, degree of aggregation and degree of evenness are highest for the semi-natural landscapes including cut-over areas, fire areas, and renew forest landscapes, their fractal dimension indexes were near to 1.0, which indicated that the semi-natural landscapes were mostly disturbed and seriously broken. For the management landscapes which include waters, farmlands, wastelands and residential areas,Degree of fragmentation, degree of aggregation and degree of evenness were lower than those of the semi-natural landscapes, which reflected that ecological environment of the Nyingchi Prefecture were in a trend of deterioration.Secondly, structure indexes of age, diameter at the breast and height were built up firstly for the ecological study on forest landscape ,and interior structure of forest landscapes were analyzed using those indexes. The results of analysis of forest landscapes interior structure were showed that coniferous forest landscapes dominate and were mainly made of natural mature forest and overmature forest in Nyingchi Prefecture ;Broad-leaved forest landscapes were subordinate and were mainly made of young forest and middle age forest.Thirdly,the evaluation system of landscape ecology was set up firstly and evaluation was carried out for landscape ecology of Nyingchi Prefecture of Tibet .The evaluation factors were confirmed by means of fuzzy mathemathics and Delphi method, and the factors weight were confirmed by means of method of hierachical analysis. the evaluationsystem of landscape ecology was builded. and present condition of landscapes ecology were quantitatively evaluated using those indexes, the comprehensive evaluation results was reflected by the synthetic calculation of all the indexes.the results were showed that excellent Landscape areas accounted for 28.0% of total areas, good 69.91%, middle 0.91% and bad 1.18% respectively,General ecological status of the prefecture was in a better situation. In which ecological situation of the forest landscapes was excellent, the situations of the shrub forests, grasslands, undeveloped lands, farmlands and waters were good, the situations of cut-over and renew forest areas were middle, and the situations of the sparse forests, fire areas and wastelands were bad. The evaluation results showed that fire disturbance, deforestation, destroying forest and opening up wasteland ,and warming up of the world climate were key driving forces of the landscape ecology change. The situations have already threatened survival of human beings. Landscapes of the prefecture were comparatively fragile and easy to be destroyed, and were difficult to be recovered once seriously destroyed. Therefore, it is not only necessary but also feasible to carry out the natural forest conservation project.Fourthly, main driving force which resulted in landscapes dynamic changes of Nyingchi Prefecture of Tibet and its influences were discussed. Driving force under the co-action between disturbances from fire and human activities as the main driving forces, developing trends of the landscape patterns of the Nyingchi Prefecture during the ten years between 1991 and 2000 were that (D farmland and residential areas of management landscapes were increased step by step under the disturbances from human beings, (2) landscape matrix (namely, forest lands) has become smaller and smaller (There were 0.2% of forest lands transferred into other types of patches.), ? total number of patches have increased, indexes of diversity and evenness were on the increase, space distributions of patches within the landscapes have become even increasingly, degree of fragmentation has tend to be on the increase, and all these changes have changed the landscape heterogeneity and led to further changes of landscape diversities.Fifthly, landscapes of Nyingchi Prefecture of Tibet in the future were estimated using the Markov matrix.and the results showed that areas of forest lands and waters decreased year by year. However, areas of other landscape types increased, and areas of the cut-overs, the fire lands, the renew forests and the residential areas increased most rapidly. Changes of landscape types of many patches resulted from human being activities, but the dominating factors of landscapes changed a little.Sixthly, landscapes layout were made firstly using Nyingchi county as example. By emphasizing considerations of landscape key elemental factors, landscape pattern optimizations and spatial ecological rationalities of the landscape units, functional sub-areas of landscapes, establishments of ecological corridors and identifications of the key plots were carried out by using an integrating method of landscape main factor analysis and pattern optimization, the technology of GIS space information treatment and the principle of operations research.Seventhly, another studies in the paper were carried out and get some results ? landscape spaces and heterogeneities were quantitatively described based on the data of the class II forest survey and TM image and so on by using the methods and technologies ofgeographic information systems and the principles and methods of landscape ecology. (2) Classification systems of the landscape ecological patterns of Nyingchi Prefecture were determined using methods of the space cluster analysis; (3) Space characteristics of landscape ecology of the Linzhi Prefecture in Tibet were quantitatively described using the landscape indexes, ? timing dynamics of landscape diversities within the prefecture were analyzed and ecological implications of the main influencing factors and the research results were clarified based on quantitative characteristic changes of the landscape patches at different times. From the conclusions, dynamics of landscapes under the severe disturbances from human being activities, especially those landscapes at high altitudes which are terribly fragile in terms of the ecological environment, could be understood. |
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