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Plant invasions and climate change – implications for the nursery industry. Topic outline. How is climate changing? Rising temperatures and plant range shifts Plant response to rising CO 2. 1. How is climate changing?. Rising CO 2 – is this change normal?. Atmospheric CO 2
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Plant invasions and climate change – implications for the nursery industry
Topic outline • How is climate changing? • Rising temperatures and plant range shifts • Plant response to rising CO2
1. How is climate changing? Rising CO2 – is this change normal? • Atmospheric CO2 • Risen from 280 pre-industrial • Near 400 today • Tied to plant sources (fossil fuels & deforestation)
1. How is climate changing? What do carbon additions mean for climate? • Rising temperatures (stronger greenhouse effect) • Altered precipitation (varies by region)
1. How is climate changing? A bigger concern: More frequent extremes Heat Waves Heat Waves Temperature variability Southwest: heat waves cause fires Last week
1. How is climate changing? A bigger concern: More frequent extremes Droughts & Floods Droughts & Floods Precipitation intensity
1. How is climate changing? A bigger concern: More frequent extremes Droughts & Floods Droughts & Floods Precipitation intensity Red River flood near Fargo, ND
1. How is climate changing? Implications of extremes on ecosystems? Increased disturbance = Increased invasion % of studies Top landscape correlates of invasion: Disturbance Vila & Ibanez, 2011
1. How is climate changing? Take home points: • Atmospheric CO2 is rising • As a result, temperatures are also rising. But, a greater concern is more frequent extremes: heat, drought, floods
2. Rising temps & range shifts Plant communities are shifting poleward and upward
2. Rising temps & range shifts Range Shifts in Yosemite 1914-1920: Grinnell collected over 4000 specimens and 3,000 pages of notes on locations collected 2005: Berkeley & USGS scientists resurveyed the same locations About half of species ranges showed a significant shift Species that expanded in range tended to expand upwards Species that contracted in range tended to do so at lower elevations American Pika’s range has retreated Biologist Joseph Grinnell, circa 1922
2. Rising temps & range shifts How much are native communities shifting? Native species and ecosystems don’t disperse very fast across landscapes There is a lot of concern that native species won’t be able to ‘keep up’ with warming ~ 1500 ft (in 90 yrs) ~ 600 ft (in 40 yrs)
2. Rising temps & range shifts BUT, Ornamental plants get a head start Native range of Rock soapwort (Saponariaocymoides) in Europe Nurseries selling that plant in Europe
2. Rising temps & range shifts People are way better dispersers of plants than plants are alone WIN! VS.
2. Rising temps & range shifts Assisted migration through gardens Our choices of garden species will affect native ecosystems in the future One example - Torreya Guardians support planting of the endangered Torreyataxifolia north of its native range in Florida. New plantsings now established in N. Carolina Torreyataxifoliaseedling
2. Rising temps & range shifts Assisted migration through gardens: Also expands invasive species Contaminated shipments (2003-2010) Live plant imports are the primary pathway for forest insect and pathogen invasions in the U.S. An estimated 12% of international imports are contaminated by non-native insects Citrus longhorned beetle exit hole in a Maple shipment
2. Rising temps & range shifts Bad News: Projected Kudzu Invasion
2. Rising temps & range shifts Take home point: • The ornamental plant trade is the primary facilitator of plant dispersal – for both native and invasive species
3. Plant response to rising CO2 Plants do better with higher CO2 Change to average plant 18% more flowers 19% more fruits 25% greater seed mass Average increased growth Trees: +50% Shrubs: +20% Flowering herbs: +15%
3. Plant response to rising CO2 Invasive plants win with rising CO2 CO2 fertilization benefits invasives over natives in comparative studies
3. Plant response to rising CO2 Invasive plants win with rising CO2 • CO2 fertilization benefits invasives over natives in comparative studies • Also, bigger = harder to kill Ambient CO2 Future CO2 Canada thistle
3. Plant response to rising CO2 Another winner from rising CO2 Higher CO2 conditions make poison ivy grow faster and become more allergenic
3. Plant response to rising CO2 Take home point: • All plants do better with higher CO2, but relative improvements matter. Watch out for hardier invasives.
Conclusions • Increased climate extremes and rising CO2 preferentially benefit invasive plants • Ecosystems are shifting poleward and upward in response to climate change • Our choices in garden species affect surrounding ecosystems. If possible, plant local(ish)