Transcript Slide 1

National Academy of Sciences
National Academy of Engineering
Institute of Medicine
National Research Council
Impacts in Southwestern Deserts
Wildfire and Invasive Species
• Nonnative grasses becoming
established in deserts:
– Red brome (in the Mojave)
– Buffelgrass (in the Sonoran)
• Grasses transform desert into
flammable grassland: fire-adapted
grasses re-establish quickly, pushing
out native species like Saguaro cactus
• Spread of grasses not directly a result
of climate change, but warming may
allow them to further spread in the
desert and extend to higher
elevations.
Image courtesy T. Esque, USGS.
National Academy of Sciences
National Academy of Engineering
Institute of Medicine
National Research Council
Impacts in Southwestern Deserts
The Piñon Pine: Past a Tipping Point
• Drought in 2000-2003 stressed a large swath of piñons, leaving
them susceptible to infestation by pine bark beetles
• This example shows how a stressful event can trigger dramatic
ecological change when an ecosystem is subject to many interacting
stresses
2002
2004
Images courtesy D. Allen, USGS.