CARBON EMISSIONS FROM THE SOIL SURFACE IN FLOODPLAIN FORESTS LOCATED IN THE SOUTH OF PRIMORSK TERRITORY

Abstract

Introduction. Evaluation of the forest ecosystems impact onto the climate requires thorough research into all the components of the carbon cycle, one of which is soil respiration. The Far East of the Russian Federation is the priority region for research of carbon pools and carbon flux in Russian forests, as the number of such field studies is very low. Aim of the research. The paper aims to define the seasonal dynamics of carbon dioxide emissions from the soil surface of floodplain forests in Primorsk Territory. Materials and methods. Ash elm planted forest formation was selected as the object for the current research. In order to measure soil-respiration intensity the authors used chamber-based statistical method during the period from 3 May to 6 August spaced one-two weeks apart. Carbon dioxide concentration measurements were made on 4 plots in River Barkukovka floodplain, the average age of stand at 50,60, 90 and 110 years. Results. Most compared plots are characterized by the significant discrepancies in the seasonal values of soil respiration intensity. The mean summer value was 5.22 gС/(m2×day). The authors showed that the seasonal dynamics of soil respiration is closely connected with the soil temperature (r2 = 0.600). The interrelation of soil respiration and air temperature (r2 = 0.255) was also detected. There was no relation identified between СО2 emission value and peculiarities of the vegetation cover (average age of stand). Other factors that limited respiration of floodplain soil on the plot under study are the soil texture and the groundwater level. During field works the soil humidity was measured at the time of sample probe on every model plot. For floodplain forests the reduction of soil respiration and increase of humidity at temperatures before 14°С is quite characteristic. The maximum emission values were obtained for temperature values exceeding 16 °С and humidity values 75-90 %. The results of the research will be used for the evaluation of carbon balance in the forests of south Sikhote Alin.