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 of soil organic matter levels to variations of climate-dependent carbon turnover parameters, which allowed us to compare the sensitivity of soil organic matter levels to net primary productivity of plant communities and plant debris decomposition rate constants across the range of soils in the European part of Russia. The results indicate that meadow steppes show the lowest sensitivity to variations of these parameters. In passing from meadow steppes to the northern taiga and to semideserts, the sensitivity increases. In general, soil organic matter levels of boreal forest ecosystems are about 2–3 times more sensitive to input and decomposition of plant debris than to decomposition of humus. In subboreal grassland ecosystems the sensitivity to humus decomposition increases and becomes closer to the degree of sensitivity shown by soil organic matter levels to variations of productivity and decomposition of plant debris. The proposed method may be useful for predicting the response of ecosystems to climatic change. Received: 1 December 1997     

Dynamics of Soil Properties and Carbon Stocks Structure in Postagrogenic Ecosystems of Southern Taiga during Natural Reforestation

Eurasian Soil Science - The dynamics of some soil properties and carbon stocks in the main components of postagrogenic ecosystems were studied during natural reforestation in dependence on the...     

Microaggregation and stability of organic matter in the forest-steppe chernozems of the Volga region

Based on the regularities of changes in the accumulation, composition, and properties of the microstructural components separated from virgin chernozems by granulodensimetric fractionation, an hypothesis relating the mechanisms of the microaggregate formation and stability with the spatial and temporal distribution of the soil organic matter was confirmed. Schemes were composed for describing the relationships of the soil microstructure with the stability of the organic matter and the dynamics of its renewal in chernozems. Parameters were proposed for characterizing the equilibrium status of soil organic matter.     

Organic carbon stabilization in microaggregates of sod-podzolic soils depending on land use

The variations in organic matter content related to changes in land use depend on the localization and soil stabilization mechanisms. Plowing of sod-podzolic soil results in a ninefold decrease in the free organic matter content. The carbon content in organic and organomineral fractions localized in microaggregates gets 2 and 1.3 times lower, respectively. The ratio between carbon fractions in coarse and fine microaggregates increases from 2 to 3. The natural forestation of agricultural lands leads to an increase in the amount of free and aggregated organic matter and a decrease in the organomineral component of microaggregates and the ratio between carbon fractions in coarse and fine microaggregates.     

The Effect of Historical and Regional Features of Land Use on the Size and Structure of Carbon Pools in the Southern Taiga and Forest-Steppe Zones of European Russia

An algorithm of regional assessment of the size and structure of the actual (corresponding to the modern state of ecosystems and land use patterns) and potential (for hypothetic natural ecosystems analogous to modern native ecosystems) pools of carbon has been developed and tested. A comparison between actual and potential values of carbon pools makes it possible to assess the integral result of land use in the studied region with multiple changes in the types of land use during the historical period. The calculations are made using a unified cartographic base and take into account the taxonomic position and texture of soil units, the types of modern land use, and the type and age structure of the reconstructed and actual vegetation. The results obtained for the southern taiga and forest-steppe zones of European Russian indicate that the modern actual carbon pool is 24% less than the potential carbon pool in Kostroma oblast (southern taiga zone) and 32% less than the potential carbon pool in Kursk oblast (forest-steppe zone). The actual phytomass reserves in these two regions have decreased by 40 and 75%, respectively, relative the potential phytomass reserves, so the portion of the soil carbon pool in the total carbon pool has increased. It is argues that the use of the territory for forestry and agriculture increases the role of the soil cover in sustaining the carbon budget of the region.     

CO<Subscript>2</Subscript> Emission and Organic Carbon Pools in Soils of the Northern Taiga Ecosystems of Western Siberia under Different Geocryological Conditions

Statistical analysis of a vast body of data collected during five field seasons (2011–2015) was performed to characterize the biological activity of soils in the northern taiga ecosystems of Western Siberia. Automorphic forest soils, hydromorphic (oligotrophic bog) soils, and semihydromorphic (flat-topped and large peat mounds) soils were characterized. Statistically significant differences of average levels of CO₂ emission from the soils were identified at the ecosystem level. The CO₂ emission from podzols of automorphic forest ecosystems at the peak of the growing season (205 ± 30 to 410 ± 40 mg CO₂/(m² h)) was significantly higher than the emission from semihydromorphic soils of peat mounds (70 ± 20 to 116 ± 10 mg CO₂/(m² h)). The presence and depth of permafrost was a significant factor that affected ecosystem diversity and biological activity of northern taiga soils. Statistically significant differences in the total, labile, and microbial carbon pools were observed for the studied soils. Labile and microbial carbon pools in the organic layer (10 cm) of forest podzols amounted to 0.19 and 0.66 t/ha, respectively; those in the organic layer (40 cm) of peat cryozems of flat-topped peat mounds reached 1.24 and 3.20 t/ha, and those in the oligotrophic peat soils (50 cm) of large peat mounds were 2.76 and 1.35 t/ha, respectively. The portion of microbial carbon in the total carbon pool (C_micr/C_tot, %) varied significantly; according to the values of this index, the soils were arranged into the following sequence: oligotrophic peat soil < peat cryozem < podzol.     

Microbial biomass carbon and the microbial carbon dioxide production by soddy-podzolic soils in postagrogenic biogeocenoses and in native spruce forests of the southern taiga (Kostroma oblast)

In two layers of the humus horizons in soddy-podzolic soils of different biogeocenoses (Kostroma oblast) representing a succession series, the carbon content in the microbial biomass (C_mic) was determined using the method of substrate-induced respiration and the rate of microbial CO₂ production (basal respiration, BR). The C_mic content was from 110 to 755 μg/g soil, and the BR was from 0.40 to 2.52 μg CO₂-C/g/h. A gradual increase in the C_mic content and BR was found in the following sequence: cropland—fallow (7-year-old)—young (20- and 45-year-old) forests—secondary and native (primary) forests (90- and 450-year-old, respectively). In the litter, the C_mic content was higher in the 45-year-old forest than in the secondary and native forests: 10423, 6459, and 4258 μg C/g of substrate, respectively. The portion of C_mic in the soil organic carbon content in the upper layer of the soils studied varied from 1.3 to 5.4%; its highest value was in the soils under the secondary and native forests. The pool of microbial biomass carbon and the microbial CO₂ production in the upper 25-cm layer of the soils were calculated.     

Spatial Distribution of the Components of Carbon Cycle in Soils of Forest Ecosystems of the Northern,Middle, and Southern Taiga of Western Siberia

Eurasian Soil Science - In the course of studies in typical forest ecosystems of the northern, middle, and southern taiga of Western Siberia performed at the peak of the growing season, the spatial...     

Assessment of Organic Carbon Stocks in Forest Soils on a Regional Scale

Eurasian Soil Science - Results of the comparison of organic carbon stocks in the automorphic and semihydromorphic forest soils are discussed. The database includes information on 289 soil profiles...     

Stabilization of organic matter in soil lysimeters

Using stationary soil lysimeters it was demonstrated that the type of phytocenose determines the processes of stabilization of organic matter and the type of litter reflects the transformation of organic matter. The maximum quantity of large aggregates at the lowest concentrations of carbon is detected in the upper horizons of soils under fallow conditions as compared to those under other communities. The maximum possible loss of carbon, as estimated by the intensity of respiration, is observed in the soils under mixed plantings, while the least was observed for agricultural lands.