IMPACT OF LITTER TURNOVER ON CARBON CYCLING IN FORESTS WITH DRAINED AND NATURALLY WET NUTRIENT-RICH ORGANIC SOILS IN LATVIA

Abstract

Litter production is a key parameter for estimation of forest soil carbon (C) stock. The aim of the study was to evaluate carbon stock in above and below-ground litter in forests with drained and naturally wet nutrient-rich organic soils in Latvia to improve National GHG inventory and to integrate data into AGM and EPIM models. To estimate C input with tree above-ground litter, sampling of litter was done in 46 research sites in Latvia. A modelling approach based on a literature review was used to estimate C input with tree below-ground litter and litter of ground vegetation. Our study highlights a connection between C input to soil with litter and stand characteristics – stand basal area, stand age and dominant tree species. There is a trend for C input from above- and below- ground litter to increase along with increasing stand basal area. In conifer stands the C input with ground vegetation increased with stand basal area, whereas for broadleaves the trend is reverse. There is still uncertainty regarding C input with below-ground litter and ground vegetation. In order to improve the modeling approach additional data and country-specific models are required.