Functional Ordination of Forest Ecosystems According to Arid Climate Trend

A type of empirical simulation modeling of global–regional changes by local geo(eco)systems based on binary ordination schemes is proposed. The gradient (ordination) analysis was used to establish the parametrical and spatial correlations of predicted changes in the two branches of small biological cycle, production and detritus, in broad-leaf, mixed, and light coniferous forests of the middle Volga Region. On this basis the empirical simulation of climatogenic changes in the biological cycle was carried out. In southern marginal forests, simultaneous rise of temperature and reduction of soil moisture content should result in the lower amount of CO2 captured by phytocoenoses from the atmosphere at photosynthesis. The ascending branch of the biological cycle will cause here an additional intensification of atmospheric greenhouse effect and thus aggravate global warming. On the northern boundary of the forest-steppe zone, broad-leaf and mixed forests will increase (and quite significantly) both their primary productivity and reserves of living organic matter. Accordingly, conservation of atmospheric carbon in perennial skeletal phytomass of these systems will increase and, as a consequence, the significance of this phytocoenotic pool as a carbon sink will increase as well. The general model scheme is offered which describes the driving forces of climatogenic successions—the fundamental mechanism of transition from functional changes to structural transformation of geosystems under the effect of global warming.