Invasive and weedy plants and global change Potential impacts of invasive and weedy plants Causes of...
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Transcript of Invasive and weedy plants and global change Potential impacts of invasive and weedy plants Causes of...
Invasive and weedy plants and global change
Potential impacts of invasive and weedy plants
Causes of invasion success
Interactions with other global change factors
REWM 3500Rangeland Plant EcophysiologyNovember 23, 2009
Of the 400 million ha of rangeland in the U.S. (42% of land area), more than 50 million ha is infested with noxious weeds
Plant invaders can:
• Completely alter the fire regime
• Alter nutrient cycling, hydrology, and energy budgets in a native ecosystem
• Greatly diminish the abundance or survival of native species
Cheatgrass (Bromus tectorum) alters fire regimes in the Intermountain West
Native sagebrush steppeFire interval – 60 to 100 yrs
Invaded by cheatgrassFire interval – 5 yrs
Sperry et al. 2006
Cheatgrass invasion alters soil nitrogen cyclingS
oil d
epth
(m
)
C3 C4 Invaded/disturbed
Non-native weeds alter soil moisture regimes
Enloe et al. 2004
Annual grass dominated
Dominated by yellow starthistleCentaurea solstitialis
Dominated by perennial grass
Causes of plant invasions
• Enemy release
• High resource availability (disturbance, elevated CO2, nitrogen deposition)
• Novel weapons (allelopathy)
Blumenthal 2005
Red brome (Bromus madritensis ssp. rubens) in the Mojave desert is greatly enhanced by elevated atmospheric CO2
Bromus versus native annuals
Bromus in fertile islands vs infertile interspaces
Ziska 2003 Response of grassland weeds to elevated CO2
Dashed line is the average response of other plants from literature
Blumenthal et al. 2008
Native monocots
Native dicots
Non-native dicotsDiffuse knapweedBaby’s breathDalmation toadflax
Increased snow inputs facilitate non-native dicot weeds
Novel weapons? Bais et al. (2003) - Allelopathy in spotted knapweed (Centaurea maculosa)