湖南桃江农业可持续发展的土地利用结构优化

Land-use Structure Optimization on Agricultural Sustainable Development in Taojiang County, Hunan Province

分析了湖南省桃江县土地资源的自然配置状况和不同坡度的土地利用结构,发现耕地不断减少、园地萎缩、水面利用不充分、宜耕缓坡地中林地面积过大,是当前土地利用中存在的主要问题。不同土地利用方式经济效益对比表明,土地利用结构不合理影响着土地利用经济效益的发挥。采用线性规划的方法,以最大纯收入为目标函数,以生态效益、社会效益及土地坡度构成为约束条件,对2 0 10年农业土地利用进行了优化配置。优化结果为,粮食作物、其他农作物、园地、渔用水面分别比2 0 0 1年增加了9 6 %、2 1 7%、4 4 9%、6 0 2 % ,林地减少了7 6 %。农业用地总面积仅比2 0 0 1年增加0 2 % ,而农业用地纯收入增长了2 2 2 %。

Sustainable utilization of natural resources is a primary rule for the optimizing land collocation. The optimal collocation of land use is an important way to realize sustainable development of regional agriculture. Agroforestry is a traditional way of land use and is recognized by people since 1970s as a sustainable way of land use and an acceptable model for modern agricultural development. Based on field investigation and governmental statistical data, the authors analyzed the natural collocation status of land resource and land use structure of different gradient in Taojiang county, Hunan province. Results showed that the area of cultivated land reduced consistently during the recent 40 years, and the area of fruit garden was also reduced during the recent 20 years, Insufficient utilization of freshwater for fishery and extra rate of forest land in 5°～15°slopes are the main issues in current land utilization and agriculture development of Taojiang county. Unreasonable land use affected the benefit exertion. According to the natural status of different gradient land collocation and the requirement of grain supply safety and forest land demand, the authors have made a program for the optimizing of agricultural land resources by 2010 in Taojiang county by ways of linear programming methods, bound for objective function, such as the area of fruit garden, cash crops and freshwater fishery. The objective function maximized the net profit of agriculture land. The simulated results showed that the total area of agriculture land would only increase by 0.2 % on the base of 2001 while the total net profit of agriculture industry can be increase by (22.2 %.) By 2010, the rates of land use for cereals, cash crops, fruit and tea gardens, forest land, and freshwater fishery will increase by 9.6 %, 21.7 %, 44.9 %, -7.6 %, and 60.2 % respectively. The optimized land use structure would not only improve the economic benefits of land, but also ensure the output of sufficient farming production and allow the returns of farming land to forestry and/or grassland in the slopes with the gradient larger than 15°. Hence, people would receive a higher economical, social, ecological profit and encourage sustainable agricultural development by the optimization of the land use structure. In this paper, the authors also had some comments on the realization of sustainable agricultural development by building up agroforestry ecosystems based on the features of land resources with different gradient. That is to increase multiple-cropping index; to develop high efficient farming systems, such as 'grain-cash crop-forage crop' system,'field crop-animal husbandry-fishery' system, 'forest-orchard-grass' system in the lands with gradient less than 5°. On lands with gradient of 5°～15°, it suggested to develop a 'forest-orchard-cash crop' and 'crop-grass' complex farming systems . On lands with the gradient larger than 15°, the suggestion is to return land from farming to forestry or grassland.