DIVERSITY, COMPLEXITY, STABILITY AND TOLERANCE OF ECOLOGICAL-SYSTEMS

Extensive data on structural and functional parameters of ecosystems of inland reservoirs on the FSU territory are analyzed. Shannon's index H is used to evaluate the systems diversity taken as measure of their complexity. An important factor regulating the diversity is the biological oxygen demand during 5 days (BOD5), the complexity decreasing as BOD5 increases. H and BOD5 values for reservoirs of different trophity and dependence H on ratio of dissolved and particulate organic matter are calculated. Diversity and mass of animal communities in lakes are negatively correlated, and proportionality coefficients in respective equations depend on the lake volume and pH or the water. Relation between primary production P(pe) (total production of the plankton, peryphyton, macrophyts, etc) and total respiration expenditures of all biological components R(e) is considered, which allows to express ecosystem production P(e) by the equation P(e) = P(pe) - R(e). P(e) values are analyzed for different types of reservoirs, along with dynamics of ratio P(e)/R(e) in the systems of various complexity. Steadiness of ecosystems and animal communities (defined as ratio of minimal to maximal biomass values per year) is positively correlated with their diversity. It can be measured, at the first approximation, by the first derivative of the equation of H to BODs relation. Stability of ecosystems is interpreted as constancy of average values of their structural and functional parameters within fairly long intervals. Hardiness of ecosystems and hydrobiont communities is interpreted as their ability to resist environmental perturbances. Ecosystems of eutrophic reservoirs are more resistant and those of oligotrophic reservoirs are less so.