Trend for Soil CO2 Efflux in Grassland and Forest Land in Relation with Meteorological Conditions and Root Parameters

The key process in understanding carbon dynamics under different ecosystems is quantifying soil CO2 efflux. However, this process can change annually as it depends on environmental variables. The results of this paper present the effects of root network, soil temperature, and volumetric water content on soil CO2 efflux, which were investigated on Retisol of two types of land uses in Western Lithuania in 2017-2019: forest and grassland. It was determined that the average soil CO2 efflux in the grassland was 32% higher than in the forest land. The CO2 efflux, average across land uses, tended to increase in the following order: 2017 < 2018 < 2019. Dry weather conditions with high temperatures during the vegetation period governed the soil CO2 efflux increase by 14%. Soil temperature (up to 20 ?) and volumetric water content (up to 23-25%) had a positive effect on the soil CO2 efflux increase on Retisol. We established that the root's activity plays one of the main roles in the CO2 production rate-in both land uses, the soil CO2 efflux was influenced by the root length density and the root volume.