Vertical pit-mounds distribution of uprooted Norway spruce (Picea abies L.): field evidence in the upper mountain belt

Abstract

Tree uprooting causes significant changes in forest habitat functioning and soil formation. In this paper soil uplifted by tree throws was compared among 15 study plots from heterogeneous Norway spruce stands of the upper mountain belt in southern Poland. Pit-mound microtopography parameters such as length, width, depth of tree-throw pits, height of the root plate, and height of mineral and organic mounds, were measured at each uprooting site. Sites were grouped in 3 age groups based on the time elapsed since uprooting. Results showed significant differences between the studied parameters among age groups. Differences were most pronounced in mean pit depth (0.52, 0.65 and 0.95 m for 5-year, 3-year, and 1-year-old pits, respectively). No significant interaction between age group and root plate height was detected by ANOVA. Regression analysis showed that pit depth decreases as root plate height increases. Redundancy analysis using pit-mound parameters as dependent variables revealed that root plate height along with slope steepness are good predictors of the volume of dislocated soil at tree-throw sites. Overall, our results suggest that the erosion expected at uprooting sites in mountain Norway spruce stands could be conveniently estimated by measuring their root plates. This may help estimate the impact of windthrow on soil microtopography and quantify its effects on soil disturbance in Norway spruce stands of the upper mountain belt.

Keywords

• Bioturbation
• Mountain Landscapes
• Microtopography
• Soil Disturbance
• Tree Uprooting