RELATIONSHIP BETWEEN DECOMPOSITION OF CELLULOSE IN THE SOIL AND TREE STAND CHARACTERISTICS IN NATURAL BOREAL FORESTS

The relationship between the decomposition of cellulose placed on and buried in the forest floor and various tree stand characteristics was studied at sites with minimal anthropogenic influence. The 22 study si tes, including both forested upland and peatland plots, were clustered in 4 catchments between 61 degrees-69 degrees N in Finland. The stand s were 60 to 320 years old and composed of varying proportions of Scot s pine (Pinus sylvestris L.), Norway spruce (Picea abies Karst.) and d eciduous species (mainly Betula spp.). Cellulose strips (softwood pulp ) were placed on the forest floor surface and buried at four depths do wn to 5 cm for two 1-year periods and the weight loss measured. Decomp osition did not significantly correlate with stand age, but was strong ly and positively correlated with stand basal area, mean tree height a nd stem volume. This was valid at all depths, and even after differenc es due to climate between catchments had been taken into account. The stem volume of Scots pine dominated plots had the highest correlation. Our results showed that decomposition of organic matter on and in the forest floor is related to the stand characteristics. This relationsh ip should be considered when comparing soil processes in different sta nds, even when comparing stands of the same tree species composition.