Climate change information: UK Hadley Centre

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

Mauna Loa

1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005

Atm

osph

eric

[CO

2] (p

pmv)

300

320

340

360

380

400

3) What makes a species invasive?c) Environmental <Global> Change Hypothesis

Global Changes• Increasing atmospheric CO2

Keeling & Whorf (2004) CDIAC

Mauna Loa

1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005

Atm

osph

eric

[CO

2] (p

pmv)

300

320

340

360

380

400

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

Keeling & Whorf (2004) CDIAC

Mauna Loa

1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005

Atm

osph

eric

[CO

2] (p

pmv)

300

320

340

360

380

400

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 growthCloses leaf stomates → uses less water

Keeling & Whorf (2004) CDIAC

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 growthCloses 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

<

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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. non-invasives

3) What makes a species invasive?c) Environmental <Global> Change Hypothesis

Global Changes• Increasing atmospheric CO2

Evidence in some specific casesBut not all invasives benefitPerhaps fast-growing and N-fixing species respond mostMediated 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 casesBut not all invasives benefit

• Precipitation changes and N deposition hypotheses relate to the ‘resource abundance’ hypothesis (next week)