Wind Erosion Modeling with Vegetation Height and Canopy Gap

The core methods described in the Monitoring Manual for Grassland, Shrubland, and Savanna Ecosystems are intended for multiple use. Each method collects data that can be used to calculate multiple indicators and those indicators have broad applicability. Two of the vegetative methods, canopy gap and vegetation height, have direct application to wind erosion assessment as described by Webb et al. in their recent paper “Vegetation Canopy Gap Size and Height: Critical Indicators for Wind Erosion Monitoring and Management”.

When considering wind erosion, vegetation is significant because it can provide structure which saps kinetic energy from wind, decreasing its ability to move sand and dust particles. Combined, measures of gaps in canopy cover and the height of vegetation can be used to understand the structure and aerodynamic properties of the vegetation at a site: the heights represent the vertical distribution of vegetation and the gaps in canopy represent the horizontal distribution. In general, taller plants provide a stronger sheltering effect than shorter ones and smaller gaps are more sheltered than larger ones. Therefore, the risk of wind erosion is inversely related to plant height and directly related to the size of gaps.

Because there are large-scale monitoring efforts in the American west like the BLM’s Assessment, Inventory, and Monitoring efforts, the NRCS’s National Resources Inventory, and the NPS’s Inventory & Monitoring which use the same core data collection methods, there are massive amounts of height and gap data available to support wind erosion assessments. The authors note that these data have already been successfully used by the National Wind Erosion Research Network to model both cropland and rangeland wind erosion and propose that widespread collection of vegetation height and canopy gap indicators should continue to enable managers to assess wind erosion risks for land health and air quality.

Webb, N. P., McCord, S. E., Edwards, B. L., Herrick, J. E., Kachergis, E., Okin, G. S., & Van Zee, J. W. (2021). Vegetation Canopy Gap Size and Height: Critical Indicators for Wind Erosion Monitoring and Management. Rangeland Ecology & Management, 76, 78–83.

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