INTEGRATED RATE METHODOLOGY APPROACH TO THE ANALYSIS OF THE SOIL ECOINDEX

Li Yang Wu Xingyi Ren Jizhou Qinghai Provincial Govt.Economic Research Center,Xining P.R.China Biosystems Research Group,Industrial Engineering Department,Texas A&M University,College Station,Texas 77843 USA Gansu Grassland Ecological Research Institute,Lanzhou P.O.Box 61,P.R.China

continuous-time Markov(CTM)process;;ecological modeling;;grassland agroecosystem;;primary production;;secondary production

The integrated rate methodology(IRM)is briefly outlined.This modeling technique can be used to study a tangled,complex ecological system.A soil submodel of the integrated agroecosystems constructed by the IRM model-building procedure is extracted and introduced here.The overall system,which consists of crop,forage,and animal submodels in addition to the soil submodel,was constructed to study the structures,responses,and processes of the agroecosystem in Loess Plateau of northwestern China.A soil ecoindex(SI)is introduced to re- flect the dynamic influences from the multi-facet components of the system:land,growthforms and environment.Parametric analysis of the soil submodel and the simulation procedure of the overall model are discussed briefly.Simulation results reveal that the potential productivity of the soil increases with the increase of the fraction of arable land used for forage production.The im- provement is much more pronounced for ravines than for hilly topography.