Simulation of degradation of pasture ecosystems of arid zone

New approaches to the study of succession dynamics are based on the original concept of system dynamics, which was used in the development of simulation models reflecting the dynamics of pasture ecosystems. The temporal dynamics of the soil and vegetation cover of the natural pastures of the Black Lands of Kalmykia reflects the degradation processes that are studied by simulation modeling. The processes of pasture degradation in the subarid belt of Southern Russia were described by ordinary differential equations. This concept is the basic one in the development of simulation models. The dynamics of changes in effective coatings for phytocenoses of pastures of Black Lands in the process of degradation was traced from the original pastures to complete desertification. Analytical solutions for various conditions of succession dynamics in the degradation of natural pasture lands are a convenient test for assessing the adequacy of simulation modeling. The initial time periods of space observations of effective coatings of phytocenoses were used to parametrize simulation models. The models are implemented in the AnyLogic simulation system. The model development process is based on visual programming using the graphical user interface. Information flows in the Anylogic environment are redistributed over time through a system of storage devices interconnected by an oriented graph of the model. A computational experiment demonstrating simulation results with different parameters was used for an indicative (qualitative) assessment of ecosystem sustainability. The results of analytical modeling using ordinary differential equations and simulation modeling showed a high identity. The study of the dynamics of pasture ecosystems using a variation experiment demonstrates the possibility of visual (cognitive) selection of the parameters of the model that determines the conditions of stationarity of pasture ecosystems. Studying the dynamics of successions of pasture phytocnoses by this method opens up new opportunities for solving problems of optimal use of biological resources and sustainability of pasture ecosystems.

simulation modeling, differential equation systems, dynamics of succession, extreme points, biodiversity, bioresource management