Climate change information: UK Hadley Centre
http://www.metoffice.gov.uk/research/hadleycentre/
3) What makes a species invasive?
c) Environmental <Global> Change Hypothesis
Global Changes
• Increasing atmospheric CO2
• Changes in temperature
• Changes in precipitation
• Nitrogen deposition
3) What makes a species invasive?
c) Environmental <Global> Change Hypothesis
Global Changes
• Increasing atmospheric CO2
400
Atmospheric [CO2] (ppmv)
Mauna Loa
380
360
340
320
Keeling & Whorf (2004) CDIAC
300
1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005
3) What makes a species invasive?
c) Environmental <Global> Change Hypothesis
Global Changes
• Increasing atmospheric CO2 has 2 direct effects on plants:
Increases photosynthesis → more C for growth
400
Atmospheric [CO2] (ppmv)
Mauna Loa
380
360
340
320
Keeling & Whorf (2004) CDIAC
300
1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005
3) What makes a species invasive?
c) Environmental <Global> Change Hypothesis
Global Changes
• Increasing atmospheric CO2 has 2 direct effects on plants:
Increases photosynthesis → more C for growth
Closes leaf stomates → uses less water
400
Atmospheric [CO2] (ppmv)
Mauna Loa
380
360
340
320
Keeling & Whorf (2004) CDIAC
300
1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005
3) What makes a species invasive?
c) Environmental <Global> Change Hypothesis
Global Changes
• Increasing atmospheric CO2 has 2 direct effects on plants:
Increases photosynthesis → more C for growth
Closes leaf stomates → uses less water
•
Recall C fixation physiology:
• C3 pathway: photorespiration wastes ATP (enzyme acts on O2
not just CO2) ; stomata must be open to maintain high enough
[CO2]
• C4: ‘pumps’ CO2 into bundle sheath cells for fixation, maintains
high [CO2] with smaller stomatal openings and less
photorespiration
• CAM: CO2 fixed in the dark, so stomata open at night (less
water loss)
•
Hypothesis: C3 benefit more from elevated [CO2]
3) What makes a species invasive?
c) Environmental <Global> Change Hypothesis
Global Changes – Increasing atmospheric CO2
From Dukes in Mooney & Hobbs (2000) – Table 5.1: Stimulation of
growth for invasive species by elevated atmospheric CO2
group
Estimate
C3herb
1.6171
A
C3woody
1.5576
A
C4
1.0200
B
3) What makes a species invasive?
c) Environmental <Global> Change Hypothesis
Global Changes – Increasing atmospheric CO2
From Smith et al. (2000): Red brome (Bromus madritensis ssp. rubens)
3) What makes a species invasive?
c) Environmental <Global> Change Hypothesis
Global Changes – Increasing
atmospheric CO2
From Belote et al. (2003) New Phytologist
161:827-835 – C4 invasive annual
grass & C3 invasive woody vine in
sweet gum forest
2001 = wet year
3) What makes a species invasive?
c) Environmental <Global> Change Hypothesis
Global Changes – Increasing
atmospheric CO2
From Belote et al. (2003) New Phytologist
161:827-835 – C4 invasive annual
grass & C3 invasive woody vine in
sweet gum forest
2001 = wet year
<
3) What makes a species invasive?
c) Environmental <Global> Change Hypothesis
Global Changes – Increasing
atmospheric CO2
From Belote et al. (2003) New Phytologist
161:827-835 – C4 invasive annual
grass & C3 invasive woody vine in
sweet gum forest
2001 = wet year
>
<
3) What makes a species invasive?
c) Environmental <Global> Change Hypothesis
Global Changes – Increasing
atmospheric CO2
From Belote et al. (2003) New Phytologist
161:827-835 – C4 invasive annual
grass & C3 invasive woody vine in
sweet gum forest

>
<
2001 = wet year
3) What makes a species invasive?
c) Environmental <Global> Change Hypothesis
Global Changes – Increasing
atmospheric CO2
From Belote et al. (2003) New Phytologist
161:827-835 – C4 invasive annual
grass & C3 invasive woody vine in
sweet gum forest

2001 = wet year
>
<
2002 = dry year
<

<
3) What makes a species invasive?
c) Environmental <Global> Change Hypothesis
Global Changes – Increasing atmospheric
CO2
From Dukes in Mooney & Hobbs (2000) –
Fig. 5.1: Stimulation of growth by
elevated CO2 for invasives vs. noninvasives
3) What makes a species invasive?
c) Environmental <Global> Change Hypothesis
Global Changes
• Increasing atmospheric CO2
Evidence in some specific cases
But not all invasives benefit
Perhaps fast-growing and N-fixing species respond most
Mediated by other resources (nutrients, water)
3) What makes a species invasive?
c) Environmental <Global> Change Hypothesis
Global Changes
• Increased temperatures
3) What makes a species invasive?
c) Environmental <Global> Change Hypothesis
Global Changes
• Increased temperatures:
• Loebl et al (2006): Spartina anglica (exotic sea grass) spread
increased with warmer water temperatures in California
•
Cheatgrass:
• Spring annual in cold climates
• Fall-germinating, winter annual in warmer climates
• Fall germinating plants more robust and produce more seeds
3) What makes a species invasive?
c) Environmental <Global> Change Hypothesis
Global Change Factors
• Precipitation changes
3) What makes a species invasive?
c) Environmental <Global> Change Hypothesis
Global Change Factors
• Precipitation changes
•
•
•
Change in timing, size of precip events
‘pulses’ are important especially in arid ecosystems
If a ‘pulse’ not used up immediately, could another species invade?
3) What makes a species invasive?
c) Environmental <Global> Change Hypothesis
Global Change Factors
• N deposition (by-product of human activity, fuels etc)
• Invasives may be ‘nitrophilous’ and invade enriched areas
• Evidence both ways:
• Vinton and Goergin (2006) Ecosystems 9:967-976: Bromus
inermis in N. Am. Central grasslands - increased growth under
enriched N; reduced growth under reduced N. Natives less
effect of enrichment.
• Thomsen et al (2006) Plant Ecology 186:23-35: elevated soil N
from nitrogen fixing shrubs did not affect competition between
native and exotic perennial grasses in CA coastal prarie
• Restoration may involve addition of carbon to soils
3) What makes a species invasive?
c) Environmental <Global> Change Hypothesis
Global Change Factors
• Increasing atmospheric CO2
• Increasing N deposition
• Global warming
SUMMARY: Global Changes
• General response is similar to that observed for elevated CO2
Evidence in some specific cases
But not all invasives benefit
• Precipitation changes and N deposition hypotheses relate to the
‘resource abundance’ hypothesis (next week)