Soil property variation within an aridisol in Big Bend National Park, Texas, USA

• Near-surface soil properties in three vegetation communities on Tornillo loam were evaluated.
• Areas of Tornillo loam at Big Bend National Park have been degrading for decades.
• Near-surface soil Na and pH greater in bare-soil areas than in creosote flats or grass patches.
• Near-surface soil Na and pH need to be considered when attempting restoration activities.

The ecological and edaphic characteristics that dictate the existence and extent of typical vegetation cover types on Tornillo loam (Ustifluventic Haplocambid), a soil common to the northern Chihuahuan Desert region within the boundaries of Big Bend National Park (BBNP) and prone to erosion, are not well-known. The objective of this study was to evaluate near-surface soil physical and chemical properties as potential explanatory characteristics for different patchy vegetation types [i.e., bare soil, creosote (Larrea tridentate) flat, and grass] on Tornillo loam in the northern Chihuahuan Desert region of BBNP in southwest Texas. Results showed that soil bulk density in the top 5 cm and penetration resistance in the top 20 cm were similar (P > 0.05) among all three vegetation cover types, but soil particle-size distributions in the top 20 cm differed significantly (P < 0.05). Extractable soil Na and soil pH in the top 6 cm were both greater (P < 0.05) in the bare-soil areas (482 mg kg− 1 and 8.9, respectively) than in the grass patches or creosote flats, which did not differ (115 mg kg− 1 and 8.5, respectively). Future research should further investigate interactions between near-surface soil chemical characteristics, particularly soil Na concentration and pH, and past and future restoration activities to promote revegetation and control erosion.