Establishment Of Material Flow Model Of The Modern Agroforestry And Pasturage Ecosystem

The compound ecosystem of agriculture, forestry and stock raising is a complicated net-work structure, which is composed by biology system, environment system and controllable system. This paper exploits the theory of ecology and mathematics and the method of system analysis to research the material exchange relationship of every part, with the aim to enhance holistic efficiency of ecosystem.In the ecosystem constituted of agriculture, forest and stock raising, the demand of remai-ning high-yield steadily make it necessary to obtain favorable circulation and exchange much sooner and much better. The organic combination of agriculture, forest and stock raising make some agriculture byproduct which mankind couldn't utilize directly conversed into useful live-stock product. In the course of conversion, the animal acted an important role by providing motility or producing organic fertilizer, which couldn't realize in separated agriculture system or forest system. These illuminate there are not only obvious relative dependence but also relative restriction ship in the exchange relation of the three systems. This is to say, in the conversion process of the energy and material, the both parties all need to consume quite some energies, and urging the production development of the other simultaneously. Therefore, in agriculture and forestry combined ecosystem, the energy and materials of the livestock husbandry come from plant system and soil, while the energy and materials of livestock farming also input and supply the soil storeroom, then enter the plant system. Three systems circulate, promote and contact mutually, and form effective circulation in the ecosystem.This paper sets up line differential equation by researching the relative parameters. Accor-ding to characteristic of structure and function of the system, the model overlook time lag. Because the forestry possess of the character of long growth period, changing slowly with time and not sensitive to feedback of system, we build up the forestry system model separately. According to the actual data we choose appropriate parameter, and then discuses and calculate the circumstance of material input and output among sub-system and the whole ecosystem.We make use of the connective stability theories to carry on the analysis of the compound ecosystem, and analysis the long-term property of actual system. Then, we discuss the actual meaning and stability point in different production structure.We differentiate the stable ability of the compound ecosystem based on the method of loop analysis, in order that demonstrate the agriculture, forest and stock raising system has structural stable ability and shows some useful direction to analyze similar structure.