No abstract

No abstract

No abstract

The impact of land use change and management on soil C sequestration was investigated during the 1980s-1990s on gray forest soils in Pushchino, and on the soddy-podzolic soil in Prioksko-Terrasny Biosphere Reserve, Moscow Region, Russia (54 • 50 N, 37 • 35 E). Mean annual rates of C sequestration after establishment of perennials (layer 0-60 cm) were 63-182 g C m −2 and 22-43 g C m −2 for gray forest and soddy-podzolic soils, respectively. Grassing resulted in higher soil C accumulation than afforestation. Cutting and application of NPK fertilisers increased soil C accumulation, but newly formed soil organic matter was less resistant to decomposition than in unfertilised soil. Preliminary calculations of C sequestration due to abandonment of arable land in Russia since the early 1990s suggest that total C accumulation in soil and the plant biomass could represent about one tenth of industrial CO 2 emissions.

Soil temperature and moisture are the main ecological factors regulating the processes of production and emission of CO 2 from soil surface. The CO 2 evolution rate from cultivated clay Phaeozem (Russia, Moscow region; 54°50'N, 37°35'E) were studied under field conditions from November 1997 to October 2002. The daily mean CO 2 evolution rate varied widely -from 0.9 to 246 mg C/m 2 /h. The total annual CO 2 flux from cultivated Phaeozem averaged 352 ± 148 g C/m 2 /year, the interannual variability amounted to 42%. We found significant linear trends (R = 0.46-0.55, P < 0.001) reflecting the relationship between CO 2 emission and soil temperature through the whole observation period and during spring and autumn seasons as well. The exponential equations described these relationships for the same periods more adequately than the simple linear equations (R = 0.62-0.68, P < 0.01). The temperature coefficient Q 10 comprised 2.3 (for the whole data set) and was essentially higher 3.2-3.6 during the spring and autumn. The correlation between CO 2 evolution rate and soil moisture was insignificant for the whole period, winter, spring and autumn seasons as well. During the summer, correlation between CO 2 evolution rate and soil moisture was positive and very close (R = 0.74, P < 0.001), indicating that the soil moisture content was a main factor limitative the rate of CO 2 emission from soil for this period.Keywords: CO 2 evolution rate; annual and seasonal CO 2 flux; cultivated Phaeozem; temperature dependence; Q 10 ; effect of soil moisture Supported by the Russian Foundation for Basic Researches, Program of RAS Presidium.