System-analytical modelling—Part I: General principles and theoretically best accuracies of ecological models. Soil-moisture exchange in agroecosystems

An efficient method for the analysis and modelling of ecological systems with fuzzy, structural, and functional organization is advanced. The method, called system-analytical modelling, is based on an information-hierarchical approach, as well as on numerical experiments with the use of vast experimental data on system dynamics. Using this method, two theoretically best accuracies of ecological models can be reached. The first accuracy characterizes an adequacy of description of the ecological processes/system structure and is found equal to 1%. The second characterizes the discrepancy between the calculated and experimental data, and is formed by a standard deviation (coefficient of variation) of 24.2%, separately for some substance and time characteristics of specific basic processes of ecological systems. New relationships of moisture exchange in freezing and thawing soils were revealed and quantitatively estimated. The developed model of soil-moisture exchange has an accuracy of 24% and allows tracing of the soil-moisture dynamics in agroecosystems of any middle latitude area with a continental climate. The mean monthly air temperature and monthly precipitation are only required to calculate this dynamics throughout single or multiple year periods.