Study On Benefit Assignment And Structure Optimization Of Agroforestry Systems In Shaanxi Qinba Mountains

Qinba Mountains Region is a complicated agroforestry system, and at the same time which has been damaged on all large scales. Therefore, it's important to settle contradictions between population growth and recourses, ecology reconstruction and economy development, and to support reforestation and nature resources conservation by optimization of structure of agroforestry systems in local region. So based on generalization of research on agroforestry systems and evaluation, structure optimization technology in this field, and the principles of ecology, biology and economics, this paper gives tentatively a theoretical and quantifiable study on model evaluation, comparison, analysis of agroforestry system. On the bases of comparison results, the author tries to erect a land structure optimization model using Mian County, Hanzhong region, in order to balance the forest construction and the adjustment of agriculture production while develop economy. The first time, the models of agroforestry systems in Qinba mountains area have been studied systematically and a comprehensive assessment system, including the effect of ecology, economy and society, been founded. It's supposed that it can be a support for exploiting special forest and land resources and raising economy. 1. Applying to system diagnosis method, this paper evaluate and diagnosis the agroforestry systems on view of habitants, government clerks, researchers as a new and practical way. The survey includes habitants, government clerks, and researcher's reactions to agroforestry systems, the benefits and disadvantages of systems in view of them. This is a great breakthrough comparing to normal assessment methods and theories, for it not only embodies the willing of participants, but can apply the bases of decision and reconstruction. We also can draw conclusion that agroforestry management is an effective way bringing comprehensive, concentrative and intensive utilization land resources from single planting, distractive and extensive farming one. 2. With AHP assessment method, several typical agriculture and forest models located in Shaanxi Qinba Mountainous Region were comprehensively assessed. 20 indexes including output, profit rate of cost, net income, forest cover ratio, and, etc. are used during the assessment. The result showed that the score of the comprehensive benefit of agroforestry management is among the best, and it's average value was 0.4153, the model of agroforestry system was a optimum option. It's the best way to develop the economy of mountainous areas; the comprehensive benefit of each model is bound up with the type of them; among them, the model of fruit growing combined with medicinal herb, forests associated with tea, with medicinal herb have relatively high comprehensive score and are optimal. 3. The score of the comprehensive benefit of forest system is relatively high, it's average value is 0.5821. However, after a careful analyses, it's turned out not good enough to be an optimum model to balance and enhance the ecological benefit and social benefit,it also fail to modify the structure to harmony with the exploitation of special forest resources and raising economy; The traditional agriculture model which gained the lowest comprehensive average benefit value 0.1640 should be optimized and modified in future. 4. By means of lineal programming, the structures of land resources of Mian County and Danfen County, such as soil used for agriculture, forest and grass to cattle-breeding and environment-protection were optimized and erected a typical model. Results showed that, by the way of optimization, the ratio of land area in Mian County used for planting, forest, cattle breeding environment-protection or other activities were adjusted from 24.5:50.4:25.1 to 29.3:47.3:23.4 for the purpose of gaining the maximum of comprehensive benefit value. The same ratio in Danfen County adjusted from 25.4:62.1:12.5 to 12.2:74.2:13.6. The ratio of planting, forest and grass themselves were optimized as to modified the structure of agriculture by increasing the proportion the cash crops and high yields economic forest. The relative ratio of provisions, cash crops and grass for cattle in Mian County were adjusted from 20.84:8.35:25.04 to 19.04:22.47:23.45,while the same ratio in Danfen County adjusted from 19.52:21.27:12.5 to 12.18:25.2:13.6. The relative ratios of man-made grass to nature grass in Mian County was adjusted from 1.5: 23.54 to 5.57:17.88, the relative ratios in Danfen County adjusted from 3.98:5.82 to 5.08:8.52. The feasibilityes of optimal scheme were analyzed and proved practical, no matter in the fields of the utilization of nature resources and of ecological, economical and social benefits. By doing so, the structures of agriculture systems were more scientific and could help changing agriculture structure of mountains areas and promoting economical condition. 5. Agroforestry system is a unstable management methods and it's assessment requires a systematic and continuous indexes system. For each model, it's comprehensive benefit score is bound up with structure, outer side environment, the prices of commodities,participator's activities and so on. So the operation of optimum of system should develop accordingly. There is an urgent need to improve the intelligent capability of governor for the purpose of agroforestry propagation and structure optimization in rural area.