GROUND VEGETATION BIOMASS AND CARBON POOL IN HEMIBOREAL OLD-GROWTH CONIFEROUS STANDS ON ORGANIC SOILS

Forest ground vegetation biomass plays a significant role in carbon (C) storage and contributes to the overall carbon pool of forest ecosystems. Ground vegetation, including understory plants, shrubs, and grasses, not only affects carbon sequestration through photosynthesis but also contributes to the carbon cycle as it decomposes and release carbon into atmosphere and soil. This process adds to soil organic matter and affects it carbon dynamics. Understanding the above and below-ground biomass of forest ground vegetation and its associated carbon pool is essential for improving local and global estimates of carbon storage and cycling, especially in forests on organic soils where the information is scarce. A total of 12 study sites were selected, with six stands dominated by Norway spruce (Picea abies (L.) H. Karst.) and six stands dominated by Scots pine (Pinus sylvestris L.). Of the selected stands, six were on drained organic soils and six on undrained organic soils. In each study site, four samples of ground vegetation biomass (both above- and below-ground) were collected in tree replicates. Each sample (above- and below-ground) was sorted into three groups (herbs, shrubs, trees), air-dried until reaching a constant weight, and then weighed to determine dry weight and carbon content. Our study provides novel information on ground vegetation biomass and C pool estimates in old-growth stands dominated by different coniferous tree species in the hemiboreal region. Ground vegetation biomass and carbon pools were similar between drained and undrained stands.