The role of climatic factors in seasonal differences of CO2 emission from the soil and litter of broadleaf forest phytocoenoses

Abstract

The article presents the results of the study of the intensity of carbon dioxide emission from the forest bedding and soil in the broad-leaved phytocoenosis of the National Nature Park “Holosiivskyi” (Kyiv green belt) in the spring and autumn periods of the year. The research was conducted in the autumn period in October, and in the spring period in April. Site coordinates: 50°17′52.7″N, 30°32′34.4″E. The experimental plot (50 × 50 m) was represented by the association Convallario majali-Quercetum roboris Shevchyk & V. Sl. in Shevchyk & al. 96, union Convallario majali-Quercion roboris Shevchyk, V. Sl. 96. It has been established that more intensive emission of CO2 occurs in the spring period compared to the autumn period. In the spring period of the year, the intensity of carbon dioxide emission from the forest litter and soil in the broad-leaved phytocoenosis ranged from 56.12 to 99.27 μmol CO2·m-2·min-1 and averaged 74.51 μmol of CO2·m-2·min-1. These differences depended on the amount of organic matter in the soil, the density of soil composition, the presence and size of tree roots, as well as the thickness of the forest bedding at the measurement points. In the autumn period of the year, the intensity of carbon dioxide emission from the forest bedding and soil was lower and in average was 68.52 μmol CO2·m-2·min-1. It was found out that higher values of carbon dioxide emissions in the spring period were determined by differences in temperature and humidity. Important factors were the increase in the supply of organic substances in the soil and more intensive processes of decomposition of these substances in the spring. Correlational analysis of the influence of climatic factors on the intensity of carbon dioxide emission proved the predominant role of temperature (r = 0.45) and a smaller influence of humidity (r = 0.15) of air and soil. In general, the conducted research confirmed the importance of monitoring the CO2 emission index of the forest bedding and soil respiration as indicators of the stability of forest ecosystems in the face of climate change.