ESTIMATIONS OF CARBON FLUXES IN STEPPE ABANDONED CROPLAND ECOSYSTEMS OF RUSSIA

Golubyatnikov L.L. , Kurganova I.N., Lopes de Gerenyu V.O.

Ecology. Economy. Informatics.
System analysis and mathematical modeling of ecological and economic systems.
2023, issue 8, pp. 10-16.
doi: 10.23885/2500-395Х-2023-1-8-10-16
(in Russian with English abstract)

Summary

In Russia, the territory with arid grassland ecosystems (steppe biome) is vast with area approximately 1.7x10⁶ km². Soils with a high content of organic matter (chernozems and kastanozems) have formed on a significant part of the steppe biome. The high concentration of soil organic matter in steppe ecosystems determines both their high level of fertility and their significant contribution to global carbon sequestration. As a result of the fact that highly fertile soils have formed in the steppes, most of the steppe biome are used in agriculture as arable land, pastures and hayfields. As a result of changes in the land use system in Russia in the 90s of the last century, large areas of the agricultural lands were abandoned in steppe biome of Russia. Steppe vegetation has restored on former croplands over the last three decades. Now secondary (restored) steppes have formed on abandoned croplands. Using a database of Federal Service for State Registration, Cadastre and Cartography and Federal Service for State Statistic, we have estimated the areas for abandoned croplands in steppe biome. According to our calculations, restored steppes on abandoned croplands occupy in Russia about 177x10³ km². Using the geoinformation-analytical method we estimated the mean annual biological productivity of the steppe ecosystems under study. Our calculations have shown that the restored steppe ecosystems on abandoned croplands accumulate 110±24 MtC per year in Russia. The average net productivity values amount to 622±136 gCm^-2yr^-1 for these ecosystems. Based on the T&P-model and the root contribution to the soil respiration in grass ecosystems, we have obtained the estimates for heterotrophic respiration from soils of the restored steppe ecosystems on abandoned croplands in Russia. The average value of heterotrophic soil respiration for the steppe ecosystems under study amounts to 338±76 gCm^-2yr^-1. We have estimated heterotrophic respiration from soils of these ecosystems in Russia as 60±14 MtC per year. According to our estimation, the restored steppe ecosystems which were formed on abandoned croplands in Russia serve as a significant sink of carbon dioxide from the atmosphere. The intensity of this carbon flux in the ecosystems under study can be estimated at 285±159 gCm^-2yr^-1. The annual accumulation of carbon dioxide in the restored steppe ecosystems on abandoned croplands of Russia is 50±28 MtC.