SOIL RESPIRATION IN STANDS OF DIFFERENT TREE SPECIES

Forest ecosystems of different tree species participate actively in climatic and biotic processes, such as photosynthesis, plant and soil respiration, therefore knowledge of soil respiration, especially of CO2 emissions to the atmosphere is of great importance. The aim of the study was to determine soil respiration rate of stands of deciduous (Betula pubescens Ehrh., Quercus robur L.) and coniferous (Larix eurolepis Henry, Thuja occidentalis L.) tree species as well as impact of abiotic (soil temperature, humidity, electrical conductivity, pH) and biotic (abundance of undergrowth, shrub, herbs) factors. Measurements of CO2 emissions, temperature, moisture and electrical conductivity were performed in-situ in the stands of different tree species with portable ADC BioScientific LCpro+ system and digital electrochemical device "Wet" (Delta-T). Soil samples were collected for the physicochemical analysis simultaneously. Chemical analysis of soil samples was done at the lab of the Environmental Research of the Aleksandras Stulginskis University by standard methods. Soil respiration was highest in the stand of Thuja occidentalis and lowest in the stand of Betula pubescens. Soil respiration intensity of the tree stands increased as follow: Thuja. Quercus. Larix. Betula. In the coniferous tree stands, the soil respiration was lower on average 27% comparing to deciduous tree stands. Soil respiration rate increased with increase of herbaceous vegetation cover and temperature. Soil respiration rate was mostly influenced by abundance of herbaceous vegetation (r = 0.91) of all biotic factors investigated, while soil temperature (r = 0.75) of abiotic factors. 60 years old stands of different tree species formed specific conditions what influenced different soil respiration rates.