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Changes in flowering and abundance of Delphinium nuttallianum (Ranunculaceae) in response to a subalpine climate warming experiment

Authors

  • FRANCISCA SAAVEDRA,

    1. Department of Biology, University of Maryland, College Park MD 20742-4415, USA,
    2. Rocky Mountain Biological Laboratory, PO Box 519, Crested Butte CO 81224-0519, USA,
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  • DAVID W. INOUYE,

    1. Department of Biology, University of Maryland, College Park MD 20742-4415, USA,
    2. Rocky Mountain Biological Laboratory, PO Box 519, Crested Butte CO 81224-0519, USA,
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  • MARY V. PRICE,

    1. Rocky Mountain Biological Laboratory, PO Box 519, Crested Butte CO 81224-0519, USA,
    2. Department of Biology, University of California, Riverside CA 92521, USA,
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  • JOHN HARTE

    1. Rocky Mountain Biological Laboratory, PO Box 519, Crested Butte CO 81224-0519, USA,
    2. Department of Environmental Science, Policy and Management, and Energy and Resources Group, University of California, Berkeley CA 94720, USA
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Francisca Saavedra, Department of Biology, University of Maryland, College Park MD 20742-4415, USA, fax 301 3149358, e-mail: saavedra@wam.umd.edu

Abstract

High-altitude and high-latitude sites are expected to be very sensitive to global warming, because the biological activity of most plants is restricted by the length of the short snow-free season, which is determined by climate. Long-term observational studies in subalpine meadows of the Colorado Rocky Mountains have shown a strong positive correlation between snowpack and flower production by the forb Delphinium nuttallianum. If a warmer climate reduces annual snowfall in this region then global warming might reduce fitness in D. nuttallianum. In this article we report effects of experimental warming on the abundance and flower production of D. nuttallianum. Plant abundance (both flowering and vegetative plants) was slightly greater on warmed than control plots prior to initiation of the warming treatment in 1991. Since 1994 experimental warming has had a negative effect on D. nuttallianum flower production, reducing both the abundance of flowering plants and the total number of flowers per plant. Flower bud abortion was higher in the heated plots than the controls only in 1994 and 1999. Results from both the warming experiment and analyses of unmanipulated long-term plots suggest that global warming may affect the fecundity of D. nuttallianum, which may have cascading effects on the pollinators that depend on it and on the fecundity of plants that share similar pollinators.

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