What makes a species invasive? b) Environmental Change Hypothesis

Mauna Loa

1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005

Atm

osph

eric

[C

O2]

(pp

mv)

300

320

340

360

380

400

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

Global Changes• Increasing atmospheric CO2

Keeling & Whorf (2004) CDIAC

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

Global Changes• Increasing atmospheric CO2

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

Global Changes• Increasing atmospheric CO2 has 2 direct effects on plants:

Increases photosynthesis → more C for growth

CO2

Photosynthesis:6CO2 + 6H2O + light C6H1206 + 6O2 + energy

3) What makes a species invasive?b) 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

H2OCO2

Photosynthesis:6CO2 + 6H2O + light C6H1206 + 6O2 + energy

3) What makes a species invasive?b) 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

• Not all species react the same:C3 plants – responsive to CO2; high stomatal opening

H2OCO2

Photosynthesis:6CO2 + 6H2O + light C6H1206 + 6O2 + energy

3) What makes a species invasive?b) 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

• Not all species react the same:C3 plants – responsive to CO2; high stomatal openingC4 plants – CO2 concentrating mechanism; small stomatal opening

3) What makes a species invasive?b) 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

• Not all species react the sameC3 plants – responsive to CO2; high stomatal openingC4 plants – CO2 concentrating mechanism; small stomatal openingCAM plants – CO2 fixed at night & stored; stomata open at night

3) What makes a species invasive?b) 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

• Not all species react the sameC3 plants – responsive to CO2; high stomatal openingC4 plants – CO2 concentrating mechanism; small stomatal openingCAM plants – CO2 fixed at night & stored; stomata open at night

H2OCO2

Photosynthesis:6CO2 + 6H2O + light C6H1206 + 6O2 + energy

3) What makes a species invasive?b) 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

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

Global Changes – Increasing atmospheric CO2

From Belote et al. (2003) New Phytologist 161:827-835 – Oak Ridge Free Air CO2 Enrichment (FACE) experiment in sweet gum forest

3) What makes a species invasive?b) 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?b) 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

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3) What makes a species invasive?b) 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

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3) What makes a species invasive?b) 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

<

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3) What makes a species invasive?b) 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?b) 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?b) 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

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2002 = dry year

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

Global Changes – Increasing atmospheric CO2

From Smith et al. (2000): Nevada Desert FACE Facility

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

Global Changes• Increasing atmospheric CO2

Evidence in some specific casesBut not all invasives benefit

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

Global Changes• Increasing atmospheric CO2

• Global warming

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

Global Changes• Increasing atmospheric CO2

• Global warming• Increasing N deposition

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

Global Changes• Increasing atmospheric CO2

• Global warming• Increasing N deposition

SUMMARY: Global Changes• General response is similar to that observed for elevated CO2

Evidence in some specific casesBut not all invasives benefit