Climate Affecting the Carbon, Phytomass and Litter Stocks in Forest Stans of the South of the European Russia

Abstract

Modern global climate change manifests in an ever intensifying fashion, affecting anthropogenic and natural systems. Bioclimatic models predict significant shifts in biome boundaries, including a reduction in the forests’ proportion in the forest-steppe areas. This process can also affect carbon stocks. The aim of the work was to assess the impact of climate and its changes on the values and their changes of the phytomass’ carbon stocks of forest stands according to the data of repeated surveys of permanent sample plots. In the southern regions of the European Russia, 8 forests were selected and trial plots were set up. Repeated surveys were carried out on the test plots in 2010–2011, 2014–2015, 2019–2020. The carbon reserves of the living and the dead components of forest stands were calculated according to taxation characteristics. The litter carbon stocks were determined by the gravimetric method. The meteorological information analysis was carried out using data from the meteorological stations closest to the objects of study. Average annual temperature for 1991–2020 increased compared to 1961–1990. by 1.13°C, which is 2.5 times more than the global average. At the same time, annual precipitation decreased from 448.2 mm to 445.4 mm. The average value of the G.T. Selyaninov’s hydrothermal coefficient for May-September during the 1961–1990 period was 0.85, and 0.79 during the 1991–2020 period. The stock of the phytomass carbon in the studied forest stands varied from 38.5 ± 7.4 t C ha–1 to 270.6 ± 52.8 t C ha–1. Repeated surveys revealed both increases and decreases in phytomass carbon stocks, which ranged from –23.8 to 31.9 t C ha–1 over a five-year interval. The phytomass carbon stocks and climatic characteristics analysis revealed a statistically significant correlation with the HTC for May-September. However, comparison of changes in phytomass with changes in the average annual temperature, annual precipitation and HTC for May-September did not reveal significant dependencies. The absence of significant correlations between changes in phytomass carbon and climatic parameters’ changes can be determined by the forest ecosystems’ stability, which ensures the preservation of their functions over several years intervals.