The Evolution Of Landscape Structure And Ecologic Security Of The Area Of Protection Of Water Source

The evolution of land use is essential to sustainable development, and relevant to mankind living and progress. In order to propose advices for rational utilization of land resources, this study initiated based on GIS and GS+, and choose the statistical information of land use status in the year of 1999,2005 and 2012 and analyzed the temporal-spatial patterns of landscape pattern in Baitiao catchment by parsing its land information and landscape structure. This aim of this study was to provide scientific evidence and basic materials for pretention of water source and promoting of land use structure. The main results showed as followsIn the whole studying period, vigorous variations of land use were found in the study area. In terms of quality, the areas of cultivated land and orchard were diminished, especially to cultivated land,7066.44hm2 of decrease in the year of 1999-2012. annual variance ratio was -2.32%. In contrast, the areas of construction land and forest land were increased by 2571.61 hm2 in 1999-2005 and 4871.03hm2 in 2005-2012, totally 7442.61 hm2 and 138.21% in those 13 years. From 1999 to 2005, the total variation of cultivated land and construction land respectively accounted for 40.35% and 34.60% of the total area of the study area, net variation were 10.51% and 10.51% respectively, total exchange capacity of 29.84% and 26.48% respectively. From 2005 to 2012, the total variation of cultivated land and construction land respectively accounted for 13.62% and 17.05% of the total area of the study area, net variation were 12.58% and 12.58% respectively, total exchange capacity of 1.04% and 0.52% respectively.In terms of plaque status, cultivated lands were mainly scattered in the study area. However, the largest plaque index of cultivated decreased continuously. From 1999-2012, the LPI of cultivated lands decreased by 30.29%, while the LPI of constructed lands increased from 1.47% to 21.68%. Furthermore, cultivated lands were mainly affected by human factors and largely unstable. The PAFRAC of cultivated lands were higher than other landscapes with approximately 1.5. Under the level of landscape scale, the fragment degree of Baitiao catchment increased gradually. The plaques were more uniform, discrete and less connectivity. Additionally, the number and diversity of plaques were increased from 3178 and 10.39/hm2 in 1999 to 3882 and 12.76/hm2 in 2005, but sharply shrunk to 3086 and 10.14/hm2 in 2012. While, the LPI were decreased from 74.82 in 1999 to 44.53 in 2012. On the other hand, the PAFRAC raised gently from 1.37 to 1.38, which indicated that disturb of landscapes by human were obviously. Moreover, the decrease of PLADJ indicated that the adjacency frequencies of homogenous plaques decreased in Baitiao catchment and distributed more discrete with higher degree of crushing. The SHDI and SHEI showed a tendency of increase, which reveal that the controlling powers of ascendant landscapes were declined, the degree of heterogenization was increased and the change of landscape types become diversity and uniformity.The degree of ecological security in the catchment was moderate, but the value of ecological security significantly declined even though there was an ascent in partial place of the catchment. In addition, in the catchment the areas represent the declining of ecological security classes were nearly 17104.74hm2 in 1999-2005, compare to 3600.39hm2 in 2005-2012. While the areas represent the raising of classes increased from 1308.61 hm2 in 1999-205 to 13528.68hm2 in 2005-2012. When compared the annual transition rates of ecological security classes 1999-2005 with those in 2005-2012, the transition rates of moderate to lower and higher to moderate in 1999-2005were higher than those in 2005-2012. However, the transition rates of tower to inferior, moderate to lower and moderate to higher in 1999-2005 were lower man those in 2005-2012.On the basic of landscape ecological security index, Geological information techniques were used to planning the ecological security areas in Baitiao catchment. The ecological security areas with lower classes were divided to control pattern, moderate classes were divided to comprehensive development patter, higher classes were divided to optimal region. What’s more this study proposed some advices and strategies.