CARBON POOLS IN OLD-GROWTH SCOTS PINE STANDS ON ORGANIC SOILS AND ITS CONCENTRATION IN DEADWOOD: CASES STUDY IN LATVIA
Carbon sequestration is crucial to mitigate climate changes, therefore it is important to have accurate estimates of carbon pools in the forest. So far, data on carbon pools in old-growth forests are very scarce, therefore aim of the study was to assess the carbon pools in old-growth Scots pine stands on organic soil and carbon concentration in deadwood of different decay classes in Latvia. Carbon content in deadwood was test in samples, collected in 26 randomly selected over mature, unmanaged stands across Latvia (five samples per decay class and tree species). Carbon pools were assessed in 38 sample plots (size 500 m2) in five Scots pine stands on wet organic soil (Caricoso- phragmitosa forest type) at the age of 167 to 203 years. Mean carbon concentration in deadwood across all species and decay classes was 46.6±1.57%. For aspen it did not change with progressing decay was found, but increase was observed for Scots pine, Norway spruce and birch. For these species difference in concentration between first three (more fresh) and last two decay classes (mean 45.9±0.9% and 49.9±1.6%, respectively) was statistically significant. Old-growth Scots pine stands on peat soils had rather large amount of deadwood: 100.6 ± 74.7 m3ha-1. However, its share in total carbon storage (290.0 ± 57.9 t ha-1) was small and most of carbon (57%) was found in soil. Mean annual carbon storage in tree biomass and deadwood decreased with stand age; its absolute value was similar in over-mature and mature (101-120 years) stands.