Predicting vegetation‐stabilized dune field morphology

The morphology of vegetation‐stabilized dune fields on the North American Great Plains (NAGP) mostly comprises parabolic dunes; stabilized barchan and transverse dunes are rare, with the exception of transverse and barchan mega‐dunes in the Nebraska Sand Hills. We present a hypothesis from a numerical dune field model explaining the vegetation‐stabilized morphology of dunes under unidirectional wind. Simulations with a range of initial dune morphologies (closely‐spaced transverse to disperse barchans) indicate that stabilized morphology is determined by the ratio of slipface deposition rate to deposition tolerance of vegetation. Slipface deposition rate is related to dune height, flux, and celerity. With a fixed depositional tolerance, large, slow‐moving dunes have low slipface deposition rates and ‘freeze’ in place once vegetation is introduced. Relatively small, fast dunes have high slipface deposition rates and evolve into parabolic dunes, often colliding during stabilization. Our hypothesis could explain differences in stabilized morphology across the NAGP and elsewhere.