QUANTIFYING DUNE FIELD REACTIVATION POTENTIAL: EXPERIMENTS AND ANALYSES FROM THE NORTHERN GREAT PLAINS

We explore new methods to predict the reactivation potential of dune fields. Dune fields vary in vegetation cover, from completely bare and active (with mobile dune forms), to fully vegetated (stable and immobile). Vegetated dunes are more habitable and valuable economically. Unvegetated or partially vegetated dune fields have high environmental value. Vegetated dunes are dominant across the Great Plains, but evidence suggests that these dunes have transitioned between vegetated and unvegetated states repeatedly on hundred to thousand year timescales in the past.

We ask: will these dunes reactivate in the near future? We first develop a framework to define the reactivation state of dune fields. We split the role of vegetation in dune fields into: (i) suppression of blowout advance, and (ii) resistance to disturbance. These two roles are mechanistically distinct and can be evaluated separately. Together, the two variables yield 4 reactivation states: (i) stable, (ii) blowout dominated, (iii) reactivating, or (iv) stable but disturbance susceptible. We detail experiments to artificially reactivate blowouts in the Middle Sand Hills (Canada), demonstrating the roles of various types of disturbance. Finally, we demonstrate a GIS methodology to quantify the present capacity of the dune field to resist disturbance. We explore how the dune field’s ‘ability to heal from disturbance’ changes under different climates and the implications for the future.

Reactivation of even a portion of Great Plains dune fields (total area ~ 182,000 km²) could result in dramatic economic losses. Our work helps develop some basic prediction tools to evaluate the future vegetation cover of this substantial and valuable land base.