Southern Shaanxi Mountain Landscape Pattern Characteristics

This paper selected the middle and lower reaches of Shima River in Shangnan County as the study area, and mountain landscape spatial pattern and landscpe pattern differentiation were selected as the main research contents at the same time. Based on the field investigation and data analysis, the changes of landscape pattern were studied quantitatively and qualitatively, and the relationship between terrain factor and landscape spatial pattern was emphatically analyzed combined with a landscape ecology evaluation system. In this process remote sensing and "3S" research technology and other techniques were used, and landscape ecology was taken as the theory instruction. The following conclusions were obtained:(1) Remote Sensing technology has some superiority in analyzing landscape pattern, and "3S" technology provides powerful support for the study. Normalized Difference Vegetation Index was used to extract information of vegetation coverage in the study area. The results showed that from 1991 to 2000, the forests and grasslands were destroyed, ecosystem deteriorated gradually, and the vegetation construction needs more attention and to be improved. The changes during 2000-2007 indicated that the quality of the grasslands and forests had been somewhat improved and the vegetation coverage had increased after conversion of cropland to forest (grass).(2) The data of the study area from 1991-2000 was studied by landscape evaluation indexes, and the results showed that:①From patch aspect: there was obvious changes in the total number of patches. The area proportion of human effect forest land is the largest. This type held absolute advantage, and could be regarded as matrix. At the same time, this type was not stable because its area changed the greatest. All in all, the increasing average area of dry land showed that the fragmentation degree of dry land was decreasing in the study area. The average area of land did not have any change, which showed that transportation and the economy developed slowly in mountain areas. The fractal dimension of each landscape was high. The patch shapes of human-effect forest land and dry land were simple gradually, while the patch shapes of waste-grass land and residential land were becoming complex gradually②From landscape aspect: the landscape fragmentation degree decreased and the diversity and evenness of landscape also decreased while the dominance increased obviously, which showed the difference in the proportion of each landscape increased, and the area of advanced pattern of patches was slightly increased. All of these showed that the landscapes' heterogeneity reduced gradually.(3) The changes of structure and area of first-class and second-class landscape indicated that the operating landscapes predominated in the study area for 17years, and the area of human-effect forest was the largest. The area of artificial landscape was small, but it was increasing all the time. Because of the enhancement of human disturbance, the operating landscapes and artificial landscapes changed greatly. The area of land had no obvious change, which showed in the limitations of development of the roads in towns in the mountain area.(4) Terrain had tremendous influence on the landscape pattern.①The research indicated that landscape patterns showed some level with the increasing of sea level elevation. Land use degree was higher in low altitude regions and human effect factor was stronger while human effect factor was relatively weaker in the high altitude regions.②Artificial landscapes was distributed mainly on the gentle slopes, human-effect forest was distributed mainly on ramps and steep slopes, and the dry land and waste-grass land was well distributed. There was little landscape pattern on the steep slopes of more than 35°, which showed that the steeper the slope, the less human disturbance had.③The landscapes were mainly distributed on half-sunny and sunny slopes which related to the higher proportion of half-sunny and sunny slopes. It also suggested that land use capability was higher on these two aspects. So, different elevation, slopes and aspects should be made full use of, and landscape should be distributed rationally and adapt to local conditions.(5) The landscape ecology of the study area had some problems. Human-effect patches had expended. The quality of forest landscape declined and its environment was unstable which might cause water and soil loss. The most unstable landscape was waste-grassland with single structure, which soil was poor with low water content. At last, landscape optimization and ecological restoration measures were proposed.