The effects of combined throughfall reduction and snow removal on soil physical properties across a drainage gradient in aspen forests of northern Minnesota, USA

Climate change is projected to alter precipitation patterns across northern latitudes, with decreased snow accumulation and summer rainfall predicted. These changes may alter soil physical properties such as soil strength, which would have implications for the feasibility of forest management activities. Reductions in summer and winter precipitation were simulated using a paired-plot design with throughfall reduction and snow removal as treatments across four soil drainage classes (well, moderately well, somewhat poor, and poorly drained) at each of three locations in northern Minnesota, USA. Snow removal caused large reductions in soil tem-perature and significantly deeper penetration of frost that varied by drainage class, where frost depth decreased with decreasing (wetter) drainage. There was a positive relationship between air freezing index and frost depth, where the rate of frost development was much higher in the snow removal treatment compared to the control (r2 of treatment = 0.8, slope = 0.093, p < 0.001; r2 of control = 0.18, slope = 0.012, p < 0.001). Throughfall reduction had limited effects on soil water content (SWC) and inconsistent effects on soil strength; relationships between SWC and strength were positive, negative, or non-existent. Based on these findings, changes in soil physical properties with altered precipitation are likely to manifest primarily in winter. Drainage class and air freezing index may be used to predict when sufficient soil frost is present for forest management activities to occur without detrimental effects to soil functions.

Automated summary

Climate change affects precipitation patterns, including decreased snow accumulation and summer rainfall, in northern latitudes. These changes have implications for soil physical properties, specifically soil strength. Findings from this study show that snow removal leads to lower soil temperature, deeper frost penetration, while reduced rainfall has inconsistent effects on soil water content and strength. Drainage class and air freezing index can be used to predict the availability of frozen soil for forest management activities.