干旱区生态环境知识资源中心

Prior research has shown a log-log correlation between ex situ air permeability (k(a)) measured at a matric potential of -50 and -100 cm H2O and saturated hydraulic conductivity (K-sat) in agricultural soils. We examined the applicability of a previously established log k(a) vs. log K-sat predictive relation in unburned and burned woodland-chaparral and coniferous soils. Specifically, we measured in situ ka in the field using the soil corer air permeameter (SCAP) and measured laboratory K-sat at on soil cores. To determine postfire soil physical changes, K-sat was transformed into water permeability, k(w). Then k(a) and k(w) were compared in unburned was higher in burned than and burned soils. The median k(a) was lower and median k(w) unburned woodland-chaparral soils. The median k(a) and k(w) were both lower in burned than unburned coniferous soils. Despite these effects, the 95% prediction interval of the predictive relation includes 80% of the burned soils and 83% of all desert soils. The RMSE values of the predicted log K-sat and measured log K-sat were 0.371, 0.552, 0.588, and 0.511 m d(-1) for unburned and burned woodland-chaparral and unburned and burned coniferous soils, respectively. In comparison, the RMSE for the predicted and measured log K-sat was 0.654 m d(-1) for an agricultural data set. The overall RMSE for unburned and burned soils including the agricultural soils was 0.551 m d(-1). This suggests that the predictive relation is applicable for unburned and burned desert soils for in situ k(a) measurements.