Influence of cryptogamic crust disturbance to wind erosion on sand and loam rangeland soils

Abstract

A portable field wind tunnel was used to assess the sediment flux rates of loam and sand textured soils in the Mallee region of southeastern Australia. Three levels of crust disturbance (nil, moderate and severe) simulating stock trampling were investigated. The results demonstrated the importance of cryptogamic crusts in binding the soil surface and providing roughness after the soil was moderately disturbed. On the loamy soil, the crust helped maintain sediment flux rates below the erosion control target to 5 g m −1 s −1 for a 65 km h −1 wind measured at 10 m height. Once the crust was severely disturbed, sediment fluxes increased to 1·6 times the erosion target. On the sandy soil, even with no crust disturbance the sediment flux was 1·6 times the erosion control target. Disturbing the crust increased sediment fluxes to a maximum of 6·7 times the erosion control target. Removal of the crust also decreased the threshold wind velocity that resulted in an increase to the risk of erosion from <5 per cent to 20 per cent.

Wind erodibility of soils at Fort Irwin, California (Mojave Desert), USA, before and after trampling disturbance: implications for land management

“…Therefore, many studies have shown that the presence of biological soil crusts reduces soil erosion by wind (e.g. Dulieu et al, 1977;Van den Ancker et al, 1985;Tsoar and Møller, 1986;Danin et al, 1989;Pluis, 1994;Williams et al, 1995;Belnap and Gillette, 1997;Marticorena et al, 1997;Belnap and Gillette, 1998;Leys and Eldridge, 1998). Even chemically killed crusts, if left undisturbed so that the polysaccharide material stays intact, appear to protect the soil surface from erosion at least in the short term (after which polysaccharide material probably degrades; Williams et al, 1995).…”

“…Sandy soils are inherently more erodible than fine-textured soils, as they have less salt, clay and silt to enhance physical crusting and soil aggregation. Therefore, sandy soils in deserts are more dependent on rocks and biological soil crusts for surface protection than other soil types (Williams et al, 1995;Leys and Eldridge, 1998).…”

A Field Guide to Biological Soil Crusts of Western U.S. DrylandsA Field Guide to Biological Soil Crusts of Western U.S. Drylands

“…Well-developed crusts (with lichens and mosses) on both silt and sandy soils have 2 to 130 times greater resistance to soil erosion than less well-developed crusts or bare soil ( Fig. 4.7; Williams et al 1995b;McKenna-Neuman 1996;Gillette 1997, 1998;Leys and Eldridge 1998). Vehicle tires result in greater damage than hooves on a given soil type (Belnap and Gillette 1998).…”

“…All experimental disturbances applied to crusts show increased sediment productionup to 35 times that of adjacent undisturbed crusts (Leys and Eldridge 1998;Williams et al 1995b). Nearby soil crusts are often buried by blowing sediment, resulting in death of photosynthetic organisms.…”

“…Detached sediment can both bury adjacent crusts, killing many crustal organisms, and/or provide material for sandblasting nearby surfaces, thus increasing wind erosion (Belnap 1995;McKenna-Neumann et al 1996;Leys and Eldridge 1998).…”