Submitted to: Forest Ecology and Management
Publication Type: Peer reviewed journal
Publication Acceptance Date: 9/1/2005
Publication Date: 12/10/2005
Citation: Sauer, T.J., Logsdon, S.D., Brahana, J.V., Murdoch, J.F. 2005. Variation in infiltration with landscape position: Implications for forest productivity and surface water quality. Forest Ecology and Management. 220:118-127. Interpretive Summary: Rainfall provides water that is essential for plant growth. How land is used affects how much of the water in rainfall that either soaks into the ground or runs off to streams, rivers, and lakes. In this study, results from three experiments were analyzed together to develop a better understanding of the movement of water in an area of northwestern Arkansas with both forests and pastures. It is now thought that soils in the bottom of the valley collect water that runs off of the soils on the hills. Trees grow very well in the valley bottom because there is more water available. Trees and grasses don't grow as well on the hills because it gets too dry during the summer. One way to improve tree and grass growth in this region is to manage the soils on the hills so more water soaks in there. Since these soils also receive animal manure, if more water soaks into these soils there will be less transport of water quality contaminants to local streams. This research is important to growers in the Ozarks as it indicates that better soil management that increases infiltration could improve all pasture and timber production and water quality.
Technical Abstract: Variation of infiltration rates with landscape position influences the amount, distribution, and routing of overland flow. Knowledge of runoff patterns gives land managers the opportunity to affect changes that optimize water use efficiency and reduce the risk of water quality impacts. The objective of this study was to assess the effect of landscape position and associated soil properties on infiltration in a small (147 ha) forest/pasture watershed in the Ozark Highlands. Three previously reported studies measured infiltration rates using double ring, sprinkling, single ring, and tension infiltrometers on soils at varying landscape positions. Although large variation in infiltration rates was observed among measurement techniques, upland and side slope soils (Nixa and Clarksville) had consistently lower infiltration rates compared to the soil in the valley bottom (Razort gravel). A conceptual understanding of watershed runoff is developed from these data that includes infiltration excess runoff from the Nixa and Clarksville soils and saturation excess runoff on the Razort gravel soil. Management of the soil water regime based on this understanding would focus on increasing infiltration in upland soils and maintaining the Razort soil areas in forest. Forest productivity would be enhanced by decreasing flooding on the Razort gravel soil and increasing stored water in upland soils and surface water quality would be improved by reducing the transport of potential water contaminants from animal manure applied to upland pastures.