|Van Pelt, Robert - Scott|
|BADDOCK, MATTHEW - London University|
|D'ODORICO, PAOLA - University Of California|
|RAVI, SUJITH - Temple University|
|BHATTACHAN, ABINASH - North Carolina State University|
Submitted to: Geoderma
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/25/2017
Publication Date: N/A
Interpretive Summary: Dust emissions from the surfaces of arid and semiarid rangelands are increasing. In general these surfaces are stabilized by grass cover and by a pavement of small stones in the bare areas, but minor disturbances and climate change favor the encroachment of shrubs and the loss of grass cover. In addition, major disturbances such as surface clearing for construction or heavy use by grazing animals can completely destroy the protective covers resulting in exposure of the whole soil to the erosive force by wind. We employed tillage, fire, simulated grazing, and simulated trampling by livestock to test the assumption that most disturbances would result in less vertical sediment flux and fine dust emissions than the highly disturbed tillage treatment. We tested 24 prepared plots with a field wind tunnel creating 12.6 meter per second (27.7 mph) wind flow. We found that the highly disturbed tilled plots produced more than 10 times as much vertical sediment flux as the other disturbances and 3 times as much fine dust emissions. Desert surfaces are resilient, but should be guarded from extreme disturbance.
Technical Abstract: Desert surfaces are typically stable and represent some of the oldest landforms on Earth. For surfaces without vegetation, the evolution of a desert pavements of gravel protects the surface from erosive forces and vegetation further protects the surface in arid and semi-arid rangelands. The susceptibility of the land surface to wind erosion is enhanced by mechanical damage to the desert pavement or vegetation losses resulting from fire or grazing. Despite the rich literature on the effects of grazing and fire on plant community composition, land degradation, and the productivity of arid landscapes, little is known about the effects of moderate grazing or fire on the erodibility of soils in desert grasslands and shrublands. Here we investigate the effect of simulated moderate grazing, simulated livestock trampling, and fire on the resulting wind erodibility and dust emissions of affected soil surfaces. To evaluate the various effects of disturbances on the susceptibility of the surface to wind erosion and dust entrainment, replicates of three plots underwent different treatments including clipping, trampling, fire, and tillage. We subsequently tested each of the treated plots with a portable field wind tunnel run at 12.6 m s-1. We found that moderate grazing and fire did not result in great soil loss in desert grasslands but that shrublands were more seriously affected by grazing and fire. Total removal of vegetation and total disturbance of the soil surface did result in greater than order of magnitude increases of vertical sediment flux and greater than three-fold increases of dust emissions.