ANALYSIS OF SOIL-VEGETATION SYSTEMS SENSITIVITY TO CHANGES OF CLIMATE-DEPENDENT CARBON TURNOVER PARAMETERS

The nonlinear model of the carbon cycle in soils (NAMSOM) was used to analyze the sensitivity of soil organic matter levels to variations in carbon turnover parameters. We were able to predict the sensitivity o f soil organic matter levels to variations of climate-dependent carbon turnover parameters, which allowed us to compare the sensitivity of s oil organic matter levels to net primary productivity of plant communi ties and plant debris decomposition rate constants across the range of soils in the European part of Russia. The results indicate that meado w steppes show the lowest sensitivity to variations of these parameter s. In passing from meadow steppes to the northern taiga and to semides erts, the sensitivity increases. In general, soil organic matter level s of boreal forest ecosystems are about 2-3 times more sensitive to in put and decomposition of plant debris than to decomposition of humus. In subboreal grassland ecosystems the sensitivity to humus decompositi on increases and becomes closer to the degree of sensitivity shown by soil organic matter levels to variations of productivity and decomposi tion of plant debris. The proposed method may be useful for predicting the response of ecosystems to climatic change.