Development and validation of vegetation indicators for the occurrence of saltation that consider the spatial distribution of vegetation

Abstract

Conventional indicators of vegetation, such as kinds of vegetation and lateral cover, assume spatially homogeneous distribution of vegetation and are insufficient for predicting wind erosion. Conventional indicators for monitoring wind erosion often focus on dust and are not directly related to soil and vegetation, which prevent practitioners from applying monitoring data to rangeland management. We proposed two new indicators—the Height Area Effect (HAE) and Total Height (TH)—as metrics of wind erosion and that consider the spatial distribution of vegetation. The HAE is the sum of windbreak effects calculated from shrub heights, and TH is the sum of the heights of shrubs within the range of calculation. We used field observation data to compare the ability of these new indicators and existing indicators (vegetation cover, shrub height, lateral cover λ, and canopy gap) to explain saltation fluxes. We conducted saltation and meteorological observations in a Nitraria sibirica community on Tsogt-Ovoo, Mongolia. We surveyed the spatial arrangements and heights of shrubs. Indicators calculated in the upwind direction from the observation point over different calculation ranges were analyzed by piecewise regression and logarithmic regression. Models were compared based on coefficients of determination. The HAE and TH had the highest coefficients of determination and the highest robustness against the different calculation ranges. This result was encouraging because HAE was the most detailed indicator of the effect of shrubs on wind erosion. The TH could be measured easily in the field and is expected to be an effective indicator for rangeland management purposes.