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Moisture may limit microbial activity in a wide range of environments including salt water, food, wood, biofilms, and soils. Low water availability can inhibit microbial activity by lowering intracellular water potential and thus reducing hydration and activity of enzymes. In solid matrices, low water content may also reduce microbial activity by(More)
Understanding nitrification rates and their regulation continues as a key area of research for assessing human's increasing impact on the terrestrial N cycle. We review the organisms and processes responsible for nitrification in terrestrial systems. The control of nitrification by substrate availability is discussed with particular attention to the factors(More)
Previous studies comparing invaded and non-invaded sites suggest that cheatgrass (Bromus tectorum L.) causes soil N cycling to increase. Unfortunately, these correlative studies fail to distinguish whether cheatgrass caused the differences in N cycling, or if cheatgrass simply invaded sites where N availability was greater. We measured soil C and N(More)
Urbanization substantially increases nitrogen (N) inputs and hydrologic losses relative to wildland ecosystems, although the fate of N additions to lawns and remnant grasslands remains contested. In montane semi-arid ecosystems, N cycling is often closely coupled to snowmelt (the dominant period of infiltration) and snow cover, which impact soil temperature(More)
We examined the influence of elevated CO2 concentration on denitrifier enzyme activity in wheat rhizoplanes by using controlled environments and solution culture techniques. Potential denitrification activity was from 3 to 24 times higher on roots that were grown under an elevated CO2 concentration of 1,000 micromoles of CO2 mol-1 than on roots grown under(More)
Plant-soil feedbacks are an important aspect of invasive species success. One type of feedback is alteration of soil nutrient cycling. Cheatgrass invasion in the western USA is associated with increases in plant-available nitrogen (N), but the mechanism for this has not been elucidated. We labeled cheatgrass and crested wheatgrass, a common perennial grass(More)
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