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The nonnative annual grass Bromus tectorum has successfully replaced native vegetation in many arid and semiarid ecosystems. Initial introductions accompanied grazing and agriculture, making it difficult to separate the effects of invasion from physical disturbance. This study examined N dynamics in two recently invaded, undisturbed vegetation associations (C₃ and C₄). The response of these communities was compared to an invaded/disturbed grassland. The invaded/disturbed communities had higher surface NH₄� input in spring, whereas there were no differences for surface input of NO₃�. Soil inorganic N was dominated by NH₄�, but invaded sites had greater subsurface soil NO₃�. Invaded sites had greater...
Categories: Publication;
Types: Citation,
Journal Citation;
Tags: Bromus Tectorum,
Ecology,
biological soil crusts,
cheatgrass,
ecosystem nitrogen, All tags...
mineralization,
nitrate leaching,
nitrogen isotopes,
plant invasion,
soil nitrogen,
surface disturbance, Fewer tags
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Destruction of habitats by invasion of non-native organisms may alter ecosystem processes. Biotic and abiotic shifts in the soil will influence available nitrogen pools, and plant species better adapted to the altered nitrogen regimes will be more competitive. We are interested in how a recent Bromus tectorum invasion will affect the nitrogen dynamics, and if the changes associated with invasion alter the competitive status of the native plants. B. tectorum, an annual grass, germinates in the fall, while most native grass species germinate and begin root activity in the spring. B. tectorum's extensive root system monopolizes the soil profile accessing available moisture and nitrogen throughout the winter. Plots...
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