Plant invasions and climate change – implications for the nursery industry
Jan 02, 2016
Topic outline
1. How is climate changing?
2. Rising temperatures and plant range shifts
3. Plant response to rising CO2
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?
1. Rising temperatures (stronger greenhouse effect)
2. Altered precipitation (varies by region)
1. How is climate changing?
A bigger concern: More frequent extremes
Southwest: heat waves cause fires Last week
Tem
pera
ture
var
iabi
lity Heat Waves Heat Waves
1. How is climate changing?
A bigger concern: More frequent extremesPr
ecip
itatio
n in
tens
ity
Droughts & Floods Droughts & Floods
1. How is climate changing?
A bigger concern: More frequent extremesPr
ecip
itatio
n in
tens
ity
Droughts & Floods Droughts & Floods
Red River flood near Fargo, ND
1. How is climate changing?
Implications of extremes on ecosystems? Increased disturbance = Increased invasion
1. How is climate changing?
% of studies
Top landscape correlates of invasion: Disturbance
Vila & Ibanez, 2011
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
1. How is climate changing?
Range Shifts in Yosemite2. Rising temps & range shifts
Biologist Joseph Grinnell, circa 1922
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
How much are native communities shifting?
2. Rising temps & range shifts
~ 1500 ft (in 90 yrs)
~ 600 ft (in 40 yrs)
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
BUT, Ornamental plants get a head start
2. Rising temps & range shifts
Native range of Rock soapwort (Saponaria ocymoides) in Europe
Nurseries selling that plant in Europe
People are way better dispersers of plants than plants are alone
2. Rising temps & range shifts
VS. WIN!
Assisted migration through gardens
2. Rising temps & range shifts
Our choices of garden species will affect native ecosystems in the future
One example - Torreya Guardians support planting of the endangered Torreya taxifolia north of its native range in Florida. New plantsings now established in N. Carolina Torreya taxifolia seedling
Assisted migration through gardens: Also expands invasive species
2. Rising temps & range shifts
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
Contaminated shipments (2003-2010)
Citrus longhorned beetle exit hole in a Maple shipment
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
Average increased growthTrees: +50%Shrubs: +20%Flowering herbs: +15%
Change to average plant18% more flowers19% more fruits25% greater seed mass
3. Plant response to rising CO2
Plants do better with higher CO2
Invasive plants win with rising CO2
3. Plant response to rising CO2
CO2 fertilization benefits invasives over natives in comparative studies
• CO2 fertilization benefits invasives over natives in comparative studies
• Also, bigger = harder to killAmbient CO2 Future CO2
Canada thistle
3. Plant response to rising CO2
Invasive plants win with rising CO2
Another winner from rising CO2
3. Plant response to rising CO2
Higher CO2 conditions make poison ivy grow faster and become more allergenic
Take home point:
• All plants do better with higher CO2, but relative improvements matter. Watch out for hardier invasives.
3. Plant response to rising CO2