Long‐term response of a Mojave Desert winter annual plant community to a whole‐ecosystem atmospheric CO2 manipulation (FACE) |
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Authors: | Stanley D Smith Therese N Charlet Stephen F Zitzer Scott R Abella Cheryl H Vanier Travis E Huxman |
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Institution: | 1. School of Life Sciences, University of Nevada, , Las Vegas, NV, 89154‐4022 USA;2. Division of Ecosystem and Earth Sciences, Desert Research Institute, , Las Vegas, NV, 89119 USA;3. Biological Resource Management Division, National Park Service, Washington Office, Natural Resource Stewardship and Science Directorate, , Ft. Collins, CO, 80525 USA;4. Ecology & Evolutionary Biology, University of California, , Irvine, CA, 92697‐2525 USA;5. Center for Environmental Biology, University of California, , Irvine, CA, 92697‐1450 USA |
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Abstract: | Desert annuals are a critically important component of desert communities and may be particularly responsive to increasing atmospheric (CO2) because of their high potential growth rates and flexible phenology. During the 10‐year life of the Nevada Desert FACE (free‐air CO2 enrichment) Facility, we evaluated the productivity, reproductive allocation, and community structure of annuals in response to long‐term elevated (CO2) exposure. The dominant forb and grass species exhibited accelerated phenology, increased size, and higher reproduction at elevated (CO2) in a wet El Niño year near the beginning of the experiment. However, a multiyear dry cycle resulted in no increases in productivity or reproductive allocation for the remainder of the experiment. At the community level, early indications of increased dominance of the invasive Bromus rubens at elevated (CO2) gave way to an absence of Bromus in the community during a drought cycle, with a resurgence late in the experiment in response to higher rainfall and a corresponding high density of Bromus in a final soil seed bank analysis, particularly at elevated (CO2). This long‐term experiment resulted in two primary conclusions: (i) elevated (CO2) does not increase productivity of annuals in most years; and (ii) relative stimulation of invasive grasses will likely depend on future precipitation, with a wetter climate favoring invasive grasses but currently predicted greater aridity favoring native dicots. |
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Keywords: |
Bromus
desert annuals elevated CO2 free‐air CO2 enrichment invasive species
Lepidium
Mojave Desert primary productivity seed bank |
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