Land Eco-Security Evaluation And Land-use Optimization In Mountainous Area At County Level Based On GIS

Sound security of land eco-system is fundamental for socio-economic development in mountainous area. The eco-security condition of land sec-system is a synthetic reflection of ecological background in a given area, which including natural and human aspects. Runoff loss caused by disadvantageous geo-conditions and improper human economic activities is the primary issue in mountain ecology, and the next are the contamination and impacts of human activities. Land-use optimization and adjustment based on eco-security is a hot-spot in eco-security study, which functions as a tool for regional agricultural structure adjustment, eco-security construction, as well as sustainable land-use management.The development and application of IT technology provides techno-support for researching on the analysis of spatial variation and quantification of relief, climate, soil, vegetation, etc. this article takes Qixia City as a case which located in Jiaodong peninsular (typical for mountains and hills), on the basis of geo-database, firstly made preliminary analysis of soil erosion change and soil heavy metal contamination, and probed the mechanism of them; then evaluated local synthetic land eco-security according to relief, annual precipitation, soil texture, soil organic matter content, soil thickness, soil heavy metal contamination, land-use intensity, vegetation, road influence extent and built area influence extent, nine indictors. Combined with the evaluating results, through land-use optimization approach, discussed the land-use optimization and land-use pattern adjustment for Qixia City to realize the renovation of local eco-security. And the conclusions are as follows:(1) During 1987 to 2003 (16 years), soil erosion in Qixia City showed general decline trend, by nearly 369.55×104t totally, erosion area of medium and above reduced by 344.15 km2; and the intensity of soil erosion declined gradually from the ridge of range (SE to NW direction) formed of Ya Hill in the east and Ai Hill in the northeast. Parts of it show fluctuation of soil erosion intensity (120-300m altitude; 8-25°slope). Woodland and orchard have obvious resistance against runoff loss, the next one is grassland. Cultivated land and unused land are prone to the impact of runoff loss, to which need to be paid more attentions.(2) Cu, Zn, Cd, Cr, Pb, Ni in soil do not exceed the standard set in"Soil environment quality standards"in our country, the spatial distribution variation is of medium, which was caused by regional lithology, soil texture and non-regional fertilization. And their spatial distribution characteristics indicate: Pb, Cr, Ni have similar spatial distribution, declining from east to west, and they show higher contents in mid-east hilly areas than in mid-west hills and slope plains, which means a sond combination of the three elements with local lithology and soil mother materials. High Cu content area is mainly in southwestern and northeastern orchards, showing close relation with the chemical fertilizers which contain Cu elements. The sample points with highest Zn content are distributed in southern orchards for the application of Zn fertilizers, and of highest Cd content are in mid orchards, which are caused by application of P fertilizer and mulch.Eco-security evaluation indicates that, the overall condition of Qixia City is secure, and parts in it are in early warning condition. Cu and Cd are two dominant elements that impact soil eco-security. Some measures should be undertaken in northeast, southeast and mid areas to guarantee the healthy of soil environment.(3) the general land eco-condition in Qixia City is sound. The land eco-security can be divided into four ranks (secure, accounting for 22.62% for total area, located in general hilly areas; less secure, 49.82% in northwest and southeast hilly areas; early warning, 20.51%, warning, 7.05%). The whole evaluation includes both single variables and multi-variables, and the results coincide with local fact. Land-use structure optimization and orchard intensive management should be highlighted to promote soil fertility, reduce runoff loss, and guarantee land eco-security safe and steady.(4) On macro-scales, three ecological zones were divided according to the vertical variation characteristics of terrain, climate, soil and vegetation in Qixia City, namely southeast and northeast plain crop ecological zone, west hilly crop-orchard-woodland zone, northwest and mid hilly woodland-grass zone. According to the traits of the three zones, nine manipulative optimization methods were put forward to provide guideline for local agricultural structure adjustment and sustainable socio-economic development.(5) On micro-scales, taking Ya Hill watershed as a case, optimal land-use pattern was delineated through minimum resistant surface, on the principle of landscape ecology and operational theory. Finally some effective measures were advanced to keep the steady of Ya Hill watershed and sustainable land-use management.Land eco-security evaluation is an exploratory research. On the principle of land eco-security evaluation, combined with the characteristics of mountainous area, this paper established spatial land eco-security evaluation model, which was helpful for further study in this realm. Other than conventional administrative unit, this paper select grid cell as basic evaluating unit in order to explore the subtle difference of ecological factors and functions differentiation. At last, optimization and adjustment were carried out at macro and micro scales respectively to make sure the coordination of total and local issues, which also increase applicability of this research.