Seasonal Wetness, Soil Organic Carbon, and Fire Influence Soil Hydrological Properties and Water Repellency in a Sagebrush‐Steppe Ecosystem

Abstract

Prescribed fire is an important tool for rangeland management in sage‐steppe ecosystems, yet the long‐term effects of this practice on soil hydraulic properties are not well known. We explore interactions among site geomorphology, soil organic carbon (SOC) soil N, soil water repellency (SWR), and plant community type on infiltration properties before fire and 8 years thereafter in a semiarid research watershed. The objective was to assess the sustainability of rangeland burning in sage‐steppe ecosystems. Many types of measurements were made in three plant communities to identify how differences in soil hydraulic properties are related to differences in plant cover and soil texture and to determine relationships among SOC, SWR, soil water contact angle, and infiltration properties. Measurements were made on transects in burned and unburned catchments. We found that severity and occurrence of surface SWR were substantially reduced 8 years after a fire within the area originally covered with mountain big sagebrush, where the fire intensity was greatest. Surface SWR was lowest in the sparsely vegetated low sagebrush, where SOC was also lowest. Unsaturated hydraulic conductivity (Kh) increased in each vegetation type over the 8‐year period after burning and was not directly related to SWR. Spatial variability in Kh was primarily controlled by soil texture, whereas differences in sorptivity (S) were controlled by SWR and aridity. SOC is not well correlated to soil surface SWR. The decadal scale changes in Kh and associations between S and site characteristics indicate forms of resilience to fire across a moisture gradient.

Effects of prescribed fire on the post‐fire hydrological processes in agro‐forest ecosystems: A systematic review and a meta‐analysis

“…Management actions with durable effects (e.g. log erosion barriers, contour felled log debris) may be welcome in those environments where the recovery of the pre‐fire rates of runoff and erosion, and SWR disappearance are longer, as reported for instance by Hubbert et al (2006), Pierson et al (2009), Fonseca et al (2017), Chandler et al (2018), Karban et al (2022) and Lucas‐Borja, De Las Heras, Moya Navarro, González‐Romero, et al (2022).…”

“…At moderate and moderate‐to‐high soil burn severities, the changes in water infiltration were the highest among all classes (e.g. Chandler et al, 2018; Pierson et al, 2008). This should be ascribed to the almost full removal of ground cover (which also alters the root distribution in the soil surface) as well as to the strong changes in soil aggregate stability, which reduces soil macro‐porosity.…”

“…Moreover, the SWR increases were strong in practically all case studies, especially in sites where the rainfall is relatively low and soil is steeper than 10%. Reductions in SWR were only reported by Huffman et al (2001), Chandler et al (2018) and Zavala et al (2009).…”