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Cheatgrass Modifies Microbial Nitrogen Cycling in Sagebrush Soils

Cheatgrass invasion not only degrades native sagebrush ecosystems and important rangelands, it can also cause soil microbial communities to change over time. These communities are responsible for converting organic soil nitrogen into plant-available inorganic nitrogen. Researchers examined nitrogen cycling rates in sagebrush and cheatgrass-invaded soils over a 100 mile range in the northern Great Basin, adding antibiotics to study the roles that soil fungi and bacteria play in nitrogen transformations. Adding a bacterial antibiotic completely stopped the organic to inorganic nitrogen conversion in cheatgrass soils. Further, there was a dramatic increase in nitrate in sagebrush soils treated with the fungal antibiotic, suggesting that fungi normally serve as a storage “sink” for this nutrient. Results point to the important role fungi play in nitrogen dynamics in native sagebrush steppe and suggest that cheatgrass’s alteration of the microbial community may make nitrogen more available further benefiting the establishment and growth of this invasive grass.

DeCrappeo, N.M., DeLorenze, E.J., Giguere, A.T., Pyke, D.A., Bottomley, P.J., 2017, Fungal and bacterial contributions to nitrogen cycling in cheatgrass-invaded and uninvaded native sagebrush soils of the western USA: Plant and Soil, p. online, http://dx.doi.org/10.1007/s11104-017-3209-x[Details]

Contact: David Pyke, FRESC, 541-750-0989, Profile

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