Distribution and Characteristics of Windthrow Microtopography on the Cumberland Plateau of Kentucky

Abstract

The abundance and characteristics of microtopography resulting from the uprooting of trees were examined on five landtypes on the northern Cumberland Plateau. Plots, 10 m by 25 m, were established at 180 locations on randomly-oriented systematic grids located in 12 first-order watersheds. The area and depth of soil disturbed were measured for each of the 524 uprootings encountered. In addition, all windthrow microtopography in a single representative hollow, 11.3 ha in area, was mapped and measured. Soil disturbance by uprooting was least on ridges, intermediate on side slopes, and greatest in coves and on lower north slopes. Percentage disturbance of the ground surface ranged from 0.4% on ridges to 2.4% in coves; number and mean area disturbed by individual uprootings ranged from 50 to 112 ha−1, and from 0.5 to 2.1 m2 along the ridge-to-cove gradient. The lower abundance of windthrow microtopography on ridges was attributed to a relatively high incidence of stem breakage vs. uprooting. Stem breakage seemed particularly common in scarlet oak (Quercus coccinea Muenchh.) which dominated ridges and south slopes. Observations made during the course of this study also suggested that concentrated subsurface water flow and concomitant decreases in tree stability may contribute to uprooting in coves and on lower slopes. Windthrow, viewed as a pedogenic process, clearly does not operate uniformly over this mountainous landscape.