Communities of plants, biological soil crusts (BSCs), and arbuscular mycorrhizal (AM) fungi are known to inﬂuence soil stability individually, but their relative contributions, interactions, and combined effects are not well understood, particularly in arid and semiarid ecosystems. In a landscape-scale ﬁeld study we quantiﬁed plant, BSC, and AM fungal communities at 216 locations along a gradient of soil stability levels in southern Utah, USA. We used multivariate modeling to examine the relative inﬂuences of plants, BSCs, and AM fungi on surface and subsurface stability in a semiarid shrubland landscape. Models were found to be congruent with the data and explained 35% of the variation in surface stability and 54% of the variation in subsurface stability. The results support several tentative conclusions. While BSCs, plants, and AM fungi all contribute to surface stability, only plants and AM fungi contribute to subsurface stability. In both surface and subsurface models, the strongest contributions to soil stability are made by biological components of the system. Biological soil crust cover was found to have the strongest direct effect on surface soil stability (0.60; controlling for other factors). Surprisingly, AM fungi appeared to inﬂuence surface soil stability (0.37), even though they are not generally considered to exist in the top few millimeters of the soil. In the subsurface model, plant cover appeared to have the strongest direct inﬂuence on soil stability (0.42); in both models, results indicate that plant cover inﬂuences soil stability both directly (controlling for other factors) and indirectly through inﬂuences on other organisms. Soil organic matter was not found to have a direct contribution to surface or subsurface stability in this system. The relative inﬂuence of AM fungi on soil stability in these semiarid shrublands was similar to that reported for a mesic tallgrass prairie. Estimates of effects that BSCs, plants, and AM fungi have on soil stability in these models are used to suggest the relative amounts of resources that erosion control practitioners should devote to promoting these communities. This study highlights the need for system approaches in combating erosion, soil degradation, and arid-land desertiﬁcation.
V. Bala Chaudhary, Matthew A. Bowker, Thomas E. O'Dell, James B. Grace, Andrea E. Redman, Matthias C. Rillig, and Nancy C. Johnson 2009. Untangling the biological contributions to soil stability in semiarid shrublands. Ecological Applications 19:110–122. http://dx.doi.org/10.1890/07-2076.1
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© Ecological Society of America, 2009.