Vegetation canopy gap size and height: Critical indicators for wind erosion monitoring and management

Authors: WEBB, NICHOLAS - New Mexico State University; McCord, Sarah; EDWARDS, BRANDON - New Mexico State University; Herrick, Jeffrey - Jeff; KACHERGIS, EMILY - Bureau Of Land Management; OKIN, GREGORY - University Of California (UCLA); Van Zee, Justin

Submitted to: Rangeland Ecology and Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/7/2021
Publication Date: 3/10/2021
Citation: Webb, N., McCord, S.E., Edwards, B., Herrick, J.E., Kachergis, E., Okin, G., Van Zee, J.W. 2021. Vegetation canopy gap size and height: critical indicators for wWind erosion monitoring and management. Rangeland Ecology and Management. 76:78-83. https://doi.org/10.1016/j.rama.2021.02.003.
DOI: https://doi.org/10.1016/j.rama.2021.02.003

Interpretive Summary: Wind erosion is a major resource concern for rangelands and indicators are needed to support wind erosion monitoring, assessment, and management. Fractional indicators of ground cover (e.g., bare soil) are often used to assess wind erosion risk. However, as wind erosion is a lateral process, information about the structure and spatial distribution of ground cover is needed to avoid under- or over-protecting soils. In this paper, we address the outstanding need for a clear and concise description for range scientists and managers of the importance of vegetation height and canopy gap size distribution for wind erosion. Measurement of these indicators have been incorporated into standardized monitoring programs globally, but have so far been under-utilized for wind erosion assessment. We review wind erosion processes to explain the physical role of these vegetation attributes. We then address the management implications including availability of data on the indicators on rangelands and needs to make the indicators and model estimates of wind erosion more accessible to the range management community.

Technical Abstract: Ground cover is an important control on rangeland wind erosion. Identifying indicators of ground cover for managers could improve wind erosion mitigation and restoration efforts. Ground cover directly protects the soil surface from erosive winds and reduces wind erosivity by extracting momentum from the air. The portion of the soil surface that is directly protected by vegetation is adequately described by fractional ground cover indicators. However, the aerodynamic sheltering effects of vegetation, which are more important for wind erosion than for water erosion, are not captured by these indicators. As wind erosion is a lateral process, the vertical structure and spatial distribution of vegetation are most important for controlling where, when, and how much wind erosion occurs on rangelands. These controlling factors can be described by indicators of the vegetation canopy gap size distribution and vegetation height, for which data are collected widely in the United States by standardized rangeland monitoring and assessment programs. In this paper we address why canopy gap size distribution and vegetation height are critical indicators of rangeland wind erosion and health. We review wind erosion processes to explain the physical role of these vegetation attributes. We then address the management implications including availability of data on the indicators on rangelands and needs to make the indicators and model estimates of wind erosion more accessible to the range management community.