Abstract
The effects of forest type, topography, and understory vegetation on infiltration rates were investigated in the Tokoro and Abashiri River watersheds, in eastern Hokkaido. This study was performed in order to develop measures for soil and water conservation. Infiltration rates were lower on skidding roads and at felling sites where skidders worked, and were higher in hardwood or mixed natural forests than in plantations of the conifers Abies sachalinensis and Larix kaempferi, which are common in Hokkaido. A higher coverage of understory vegetation resulted in a higher infiltration rate, suggesting that vegetation root growth may increase soil porosity. To promote soil porosity, in the interests of soil and water conservation, mechanized operations by skidders should be minimized and stand density should be controlled to facilitate invasion by hardwood or understory vegetation.
