Assessments of net greenhouse gas (GHG) emissions in forest land with drained organic soils conducted within the scope of National GHG Inventories require reliable data on litter production and information on carbon (C) input to soil. To estimate C input through tree above-ground litter, sampling of above-ground litter was done in 36 research sites in Latvia representing typical forests with drained organic soils in the hemiboreal zone. To estimate C input through tree below-ground litter and litter from ground vegetation, modelling approach based on literature review and data on characteristics of forest stands with drained organic soils in Latvia provided by the National Forest Inventory (NFI) was used. The study highlighted dependence of C input to soil through litter production on the stand characteristics and thus significant differences in the C input with litter between young and middle-aged stands. The study also proved that drained organic soils in the middle-aged forests dominated by silver birch, Scots pine and Norway spruce may not be the source of net GHG emissions due to offset by C input through litter production. However, there is still high uncertainty of C input with tree below-ground litter and ground vegetation, particularly, mosses, herbs and grasses which may have crucial role in C balance in forests with drained organic soils.

Keywords: forests, drained organic soils, litter production, carbon input, National GHG Inventory