Quantity, vertical distribution and morphology of fine roots in Norway spruce stands with different stem density

Abstract

In the study, the influence of stand density on quantitative and morphological parameters of fine roots with the diameter less than 2 mm was analysed. The results confirmed the differences of the fine root distributions and the total fine root mass between stands with different density. The Norway spruce stand with lower stem density has a lower overall fine root mass but, at the same time, a higher fine root mass regarding the single tree. In the litter (Ol, Of-horizons), the fine roots are present only in the plot with higher density. The cumulative proportion of fine root biomass in the layer 0-10 cm reaches 67% in the plot with lower density and 78% in the plot with higher density. In the lower density plot, a lower proportion of fine roots in the diameter class under 0.25 mm was found in all analysed parameters. Specific root length, root surface area and root tissue density reflect the different diameter structure of fine roots in the surveyed plots. We suppose the stand density significantly affects the fine root system, especially by the change of moisture regime in the litter and in the upper parts of the A-horizon. Despite the high fine root dynamics of single trees, the Norway spruce stand with the lower stem density is not able to effectively utilize the entire soil space.