Assessment Of Eco-vulnerability And Eco-engineering Campaigns In Agro-grazing Ecotone Of North China

The agro-pastoral ecozone in northern China is not only an important link between agricultural and pastoral areas, but also an ecological protective belt for the eastern agricultural plain, playing an indispensable role in preventing the southward desertification and water conversation for rivers. Thus it is important for the ecological protection and improvement in China. Due to climate change and excessive use of natural resources, (such as overgrazing, and over-logging), the farming-pastoral zone in northern China is faced with more pressure than it can bear. Linxi county is a typical example in this area. Due to long-term over-grazing, wasteland reclaiming and mining, plus population growth and the urbanization, ecological problems in Linxi County become very prominent. Through empirical research, this paper explores methods to evaluation the ecological vulnerability in northern China, rating the frangibility of Linxi county, revealing its ecological vulnerability mechanism, explaining its characters in spatial terms, summarizing and evaluating experience, technical measures and achievements of the programs for ecological reclamation,and exploring technical system and development mode for ecological improvement. The study aims to provide scientific basis for the ecological development in Linxi County and its surrounding areas as well as the restructuring of cropping patterns and the long-term development of grassland grazing.In terms of methodology, this study adopts the quantitative remote sensing techonology other than the traditional statistical model in the evaluation of the ecological vulnerability in the area. It analyses the space-time characteristics and the special rule of primary productivity in ecological system in Linxi country. Meanwhile, through case study, it analyses the social economic impact of the ecological reclamation programs adopted in Linxi County and assesses its effect.This study analyses the environmental problems in Linxi County and establishes an indicator system and index model for the vulnerability evaluation in the county, in which 8 factors including climate, topography, force, economic development and 18 indicators are selected, covering the cause of formation and characterization of ecological vulnerability. We proposed the rating system for the ecological vulnerability in Linxi county, using the major component analysis method to determine the relative weight of each indicator, thus quantitatively determining the level of ecological vulnerability in the county. The formation mechanism of ecological vulnerability was analysed from the perspective of climate change and human activities. The relationship between the space-time characteristics of ecological vulnerability in Linxi county and the inter-annual precipitation was analysed from the perspective of vegetation index and vegetation coverage by use of quantitative MODIS remote sensing..On this basis, it further analysed the technical measures and impact of ecological management programmes in Linxi county, providing technical support and theoretical basis for further ecological management in the county. At the same time, it actively explores the assessment methods for ecological vulnerability in north china in order to promote the sustainable ecological environment and economic and social development in agro-pastoral ecozone of north china. The ecological vulnerability of the agro-pastoral ecozone in north China, as represented by Linxi County, was rated in 5 levels:mild, low, moderate, high and extreme vulnerability, respectively corresponding to the ecological vulnerability index (EVI):EVI that is below 25 is mild vunerability; between 26 and 40, low vulnerability; between 41 and 55, moderate vulnerability; between 56 and 70, high vulnerability and above 70, extreme vulnerability. Result shows that the ecological vulnerability in Linxi county is 41.59, falling into the moderate vulnerability category. Besides, the vulnerability demonstrates special characters, with the mid and south areas above the moderate level while the north and river valleys at the mild and low level.The vegetation index and the vegetation coverage rate in linxi is differenct in areas with great change every year, due to the change of annual percipatation. During 2000 to 2009, the average NDVI of Linxi county is 0.59, with the maximum value at 0.68 in 2004 and the minimum value at 0.42 in 2000. The gap is as large as 0.26. The higher the NDVI is,the more green vegetation there are and the healthier the eco-system is. During 2000 and 2009, the average vegetation coverage rate of Linxi County is 0.63 with the highest value at 0.77 in 2004, and the lowest value at 0.39 in 2000, only half of the maximum value. The huge inter-annual change of vegetation coverage rate shows that the eco-system is easily affected by the level of precipitation, which is clearly a sign of vulnerability.In recent years, Linxi county develops a ecological management system through many reclamation programs. Mature technical systems include artificial grass planting and its sustained utilization, restoration of vegetation on reclaimed land, the restoration of degraded and desertificated grassland, the grass planting on the saline beach and the breeding of excellent forage grasses. Linxi County also adopted some technical measures such as planting grass and fodder crops in the dry mountain areas, forage seed production in the low hill areas and grass products in the river valleys.Ecological management practive in Linxi County was quite successful. Returning farmland to grassland has played a positive role in local social economic development. It not only increased imployment, but also spurring local economy and raise the per capita net income of farmers and pasturers. In recent years, local revenue and per capita income of farmers have grown rapidly. Compared with 2000, the increase rate local revenue and per capita income of farmers were 57% and 88% respectively in 2008. Ecological reclamation projects has helped optimize the planting structure in Linxi County. Artificial grassland increased from 5.3% to 25.0%, which nearly rose by 20.0%. Cash crops increased from 8.3% to 13.3% while food crops decreased by 24.7%. These projects also help improve the agro-pastoral infrastructure in the County and promote industrial readjustment and shift of economic modeland. From the long term perspective, these projects are very important for eco-safety and the coordinated development of the eco-environment and social and economic development. However, the shortage of forage supply in this areas is still very severe.To summarize, this study adopts remote sensing technology to analyse the ecological vulnerability from the perspective of vegetation coverage according to the importance of vegetation in the ecological system. It develops the ecological vulnerability evaluation methods and techniques and provides technical support to further assessment of ecological vulnerability in northern China.