Impact of Sika Deer on Soil Properties and Erosion

Ground cover by understory vegetation and litter is one of key factors for mitigating soil erosion as well as for maintaining soil properties as an ecosystem function. Reduction of understory vegetation by the overpopulation of deer can elevate the rate of soil erosion due to rain splash and overland flow. Changes in surface soil conditions also occur in soil properties including bulk density, particle size distribution, and organic matter contents. Furthermore, soil erosion on hillslope can affect in-channel sediment transport of headwater catchments, because of tight linkages between hillslopes to streams at incised valleys. Thus, catchment scale conservation needs to be established for mitigating the effects of deer overpopulations on occurrence of surface runoff and soil erosion and consequent changes in sediment dynamics and water quality in downstream. This chapter will explore how changes in vegetation cover by deer affect hydrologic and geomorphic processes related to the soil at scales of hillslopes and headwater catchment scales.