Runoff and Sediment Yields from Runoff Plots on Chained Pinyon-Juniper Sites in Utah

Abstract

and 150~cm depths in the woodland is due in part to deeper root penetration by the pinyon and juniper trees. Crested wheatgrass roots are concentrated in the surface 45 cm of soil profile, while juniper and pinyon roots are concentrated in the upper 90 cm of soil profile with sinker roots that penetrate even further. This, combined with a seasonal growth of crested wheatgrass as compared with pinyon and juniper, which may transpire a major part of the year, would contribute to less soil moisture in the woodland. There is no evidence that surface soil moisture conditions have been improved enough on the debris-in-place treatments to affect seedling establishment. It is speculated that young trees missed in the chaining process and also deep-rooted shrub species on debris-in-place treatments may benefit most from increases in soil moisture, especially at soil depths beyond 60 cm. Finally, during the course of this study there was no indication of any excess moisture for eventual deep seepage. Areas similar to the Milford site, which have had springs develop following chaining, are areas that have zones of subsurface flow as a result of snowmelt at elevations above the chaining project. The subsurface flow, which was normally consumed by the pinyon-juniper woodland, is not entirely consumed (transpired) under a grass cover. As a result, springs may develop or increase in flow as a result of the chaining. However, based on this study, the water is apparently not due to on-site additions to soil moisture.