FINE-ROOT VITALITY IN A NORWAY SPRUCE STAND SUBJECTED TO VARIOUS NUTRIENT SUPPLIES

The vitality of fine roots in a Norway spruce stand subjected to appli cation of ammonium sulphate (NS), wood ash (A) and nitrogen-free ferti lizer (V) respectively, was investigated using i) vitality classificat ion of fine roots based on morphological characteristics and ii) the t riphenyl tetrazolium chloride (TTC) method of estimating dehydrogenase activity. Although the NS-treated areas showed a 30% increase in abov e-ground production in response to the NS-application, the vitality of the fine-root system in the humus layer appeared to be in a state of deterioration, as indicated by a decrease in fine-root biomass, an inc reased amount of dead fine (0-1 mm) and small (1-2 mm) roots, a decrea sed specific root length (SRL = fine root length/fine root dry weight) and an increased dehydrogenase activity, The impact of the the A and V treatments was reflected in a decrease in fine-root biomass and an i ncrease in SRL. The results make it clear that in order to study the v itality of forest trees, both fine-root studies and studies of above-g round tree parts are necessary.