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Climate change and grazing alter invasive and native perennial grass stem recruitment

Date: October 08, 2015

Understanding the invasive smooth brome competitive abilities over native western wheatgrass provides important implications for predicting vegetation dynamics under climate change


RMRS scientists and university collaborators collect buds from the Buffalo Gap National Grassland for a growth chamber experiment.
RMRS scientists and university collaborators collect buds from the Buffalo Gap National Grassland for a growth chamber experiment.
The robust vegetative reproductive capacity of smooth brome under a range of environmental conditions is a key mechanism enabling the expansion of smooth brome into western wheatgrass-dominated mixed-grass prairie in North America. Mixed-grass prairie dominated by western wheatgrass experiencing repeated defoliation may require longer recovery times and be more susceptible to smooth brome invasion due to the negative impact of grazing on western wheatgrass bud outgrowth.

Seedling recruitment of perennial grasses is rare as most tillers (grass stems) are recruited from vegetative belowground buds. Successful tiller recruitment and establishment of native perennial grasses via the bud bank will be necessary for mixed-grass prairie to be resilient to climate change, plant invasions and grazing.

Research Objectives

  1. Compare how spring temperature altered bud outgrowth of native western wheatgrass (Pascopyrum smithii) and introduced smooth brome (Bromus inermis),

  2. Compare how watering frequency altered bud outgrowth of these two species, and

  3. Evaluate how clipping interacts with spring temperature or watering frequency to affect western wheatgrass bud outgrowth.

Key Findings

  • Smooth brome had more buds per tiller and initiated a greater proportion of these buds than western wheatgrass under all temperature and moisture conditions.

  • Western wheatgrass bud development was reduced at 24°C. Intermittent watering did not significantly impact bud outgrowth of either species.

  • Clipping increased western wheatgrass bud mortality and reduced its bud development for the two-week period of the study.

A belowground bud of western wheatgrass still covered by its prophyll (left), a protective outer leaf, and a bud growing out from the base of its parent stem and past its prophyll (right).
A belowground bud of western wheatgrass still covered by its prophyll (left), a protective outer leaf, and a bud growing out from the base of its parent stem and past its prophyll (right).

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Principal Investigators: 
Principal Investigators - External: 
Lan Xu - South Dakota State University
Forest Service Partners: 
Buffalo Gap National Grasslands
External Partners: 
Yuping Rong, China Agricultural University
Research Location: 
Buffalo Gap National Grasslands, South Dakota