Incorporating Hydrologic Data and Ecohydrologic Relationships into Ecological Site Descriptions

A review of concentrated flow erosion processes on rangelands: Fundamental understanding and knowledge gaps

“…Plant community physiognomy affects concentrated flow by controlling the connectivity of runoff and sediment sources and the energy of overland flow where it does occur (Williams et al, 2016a(Williams et al, , 2014a(Williams et al, , 2016b. On well vegetated rangelands, downslope transmission of runoff and erosion generated by rainsplash and sheetflow in isolated bare or sparsely vegetated patches is limited by ground cover or roughness elements that promote infiltration and deposition (Pierson et al, , 2009Reid, Wilcox, Breshears & MacDonald, 1999;Wilcox, Breshears & Allen, 2003).…”

“…These relationships are enhanced on steep slopes and where overland flow is promoted by soil water repellency Shakesby, & Doerr, 2006;Williams et al, 2014). Greater raindrop impact and increased sediment availability after canopy and ground cover removal result in increased soil detachment and transport from combined rainsplash and sheetflow processes (Pierson et al, 2009(Pierson et al, , 2013b(Pierson et al, , 2014Williams et al, 2016Williams et al, , 2014aWilliams et al, , 2016b. Reductions in ground cover (decreased surface roughness) abate surface retention of runoff, allowing flow to concentrate and move downslope with greater velocity, erosive energy, and transport capacity (Al-Hamdan et al, 2013;Pierson et al, 2009Pierson et al, , 2013aPierson et al, , 2008bShakesby et al, 2006;Williams et al, 2014aWilliams et al, , 2016a.…”

“…Accurate partitioning of hillslope erosion into interrill and concentrated-flow-dominated processes has a significant implication on rangeland erosion modeling especially following disturbances. Several studies (e.g, Al-Hamdan, Pierson, Nearing, and Williams (2012b), Pierson et al (2013aPierson et al ( , 2013b; Williams, Pierson, & Spaeth, 2016;Williams et al, 2014aWilliams et al, , 2016aWilliams et al, , 2016b have demonstrated a significant increase in concentrated flow erosion when shrub-dominated rangeland are disturbed by fire or woody species encroachment compared to undisturbed conditions. Concentrated flow erosion is a complex process because flow networks have a dual function of sediment and runoff production and storage as well as that of transport of these resources off-site.…”

Long‐term evidence for fire as an ecohydrologic threshold‐reversal mechanism on woodland‐encroached sagebrush shrublands

“…woodlands has significantly altered a vast expanse of the western United States Miller et al, 2011;Miller, Bates, Svejcar, Pierson, & Eddleman, 2005;Miller & Rose, 1995;Miller, Tausch, McArthur, Johnson, & Sanderson, 2008;Romme et al, 2009). Woodland encroachment on sagebrush shrublands poses a host of negative ramifications to ecosystem services, including degradation of understory vegetation and wildlife habitat, limited forage for wild and domestic animals, and high rates of run-off and soil loss (Bates, Davies, & Sharp, 2011;Coates et al, 2017;Davies et al, 2011;Miller et al, 2005Miller et al, , 2011Miller, Svejcar, & Rose, 2000;Petersen & Stringham, 2008;Petersen, Stringham, & Roundy, 2009;Pierson et al, 2010;Williams, Pierson, Al-Hamdan, et al, 2014;Williams, Pierson, Robichaud, et al, 2016;Williams, Pierson, Spaeth, et al, 2016). shrublands within the Great Basin Region Miller et al, 2011).…”

“…The progression of pinyon and juniper dominance of sagebrush shrublands has been characterized into three phases (Phases I-III; see Miller et al, 2005;Miller et al, 2008). Phase III is perpetuated by tree dominance of site resources and high rates of run-off and long-term soil loss from well-connected bare intercanopy areas (the soil erosion feedback; Miller et al, 2005;Miller et al, 2008;Petersen et al, 2009;Williams, Pierson, Al-Hamdan, et al, 2014;Williams, Pierson, Spaeth, et al, 2016). Under these conditions, sagebrush islands and well-vegetated interspaces between shrubs and trees intercept rainfall and isolated overland flow and promote infiltration and soil retention.…”