Climate change information: UK Hadley Centre

3)What makes a species invasive? c) Environmental Change Hypothesis Global Changes Increasing atmospheric CO 2 Changes in temperature Changes in precipitation Nitrogen deposition

3)What makes a species invasive? c) Environmental Change Hypothesis Global Changes Increasing atmospheric CO 2 Keeling & Whorf (2004) CDIAC

3)What makes a species invasive? c) Environmental Change Hypothesis Global Changes Increasing atmospheric CO 2 has 2 direct effects on plants: Increases photosynthesis → more C for growth Keeling & Whorf (2004) CDIAC

3)What makes a species invasive? c) Environmental Change Hypothesis Global Changes Increasing atmospheric CO 2 has 2 direct effects on plants: Increases photosynthesis → more C for growth Closes leaf stomates → uses less water Keeling & Whorf (2004) CDIAC

3)What makes a species invasive? c) Environmental Change Hypothesis Global Changes Increasing atmospheric CO 2 has 2 direct effects on plants: Increases photosynthesis → more C for growth Closes leaf stomates → uses less water Recall C fixation physiology: C 3 pathway: photorespiration wastes ATP (enzyme acts on O 2 not just CO 2 ) ; stomata must be open to maintain high enough [CO 2 ] C 4 : ‘pumps’ CO 2 into bundle sheath cells for fixation, maintains high [CO 2 ] with smaller stomatal openings and less photorespiration CAM: CO 2 fixed in the dark, so stomata open at night (less water loss) Hypothesis: C 3 benefit more from elevated [CO 2 ]

3)What makes a species invasive? c) Environmental Change Hypothesis Global Changes – Increasing atmospheric CO 2 From Dukes in Mooney & Hobbs (2000) – Table 5.1: Stimulation of growth for invasive species by elevated atmospheric CO 2

groupEstimate C3herb1.6171A C3woody1.5576A C B

3)What makes a species invasive? c) Environmental Change Hypothesis Global Changes – Increasing atmospheric CO 2 From Smith et al. (2000): Red brome (Bromus madritensis ssp. rubens)

3)What makes a species invasive? c) Environmental Change Hypothesis Global Changes – Increasing atmospheric CO 2 From Belote et al. (2003) New Phytologist 161: – C 4 invasive annual grass & C 3 invasive woody vine in sweet gum forest 2001 = wet year

3)What makes a species invasive? c) Environmental Change Hypothesis Global Changes – Increasing atmospheric CO 2 From Belote et al. (2003) New Phytologist 161: – C 4 invasive annual grass & C 3 invasive woody vine in sweet gum forest 2001 = wet year <

3)What makes a species invasive? c) Environmental Change Hypothesis Global Changes – Increasing atmospheric CO 2 From Belote et al. (2003) New Phytologist 161: – C 4 invasive annual grass & C 3 invasive woody vine in sweet gum forest 2001 = wet year < >

3)What makes a species invasive? c) Environmental Change Hypothesis Global Changes – Increasing atmospheric CO 2 From Belote et al. (2003) New Phytologist 161: – C 4 invasive annual grass & C 3 invasive woody vine in sweet gum forest 2001 = wet year < > 

3)What makes a species invasive? c) Environmental Change Hypothesis Global Changes – Increasing atmospheric CO 2 From Belote et al. (2003) New Phytologist 161: – C 4 invasive annual grass & C 3 invasive woody vine in sweet gum forest 2001 = wet year < >  2002 = dry year < < 

3)What makes a species invasive? c) Environmental Change Hypothesis Global Changes – Increasing atmospheric CO 2 From Dukes in Mooney & Hobbs (2000) – Fig. 5.1: Stimulation of growth by elevated CO 2 for invasives vs. non- invasives

3)What makes a species invasive? c) Environmental Change Hypothesis Global Changes Increasing atmospheric CO 2 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 Change Hypothesis Global Changes Increased temperatures

3)What makes a species invasive? c) Environmental 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 Change Hypothesis Global Change Factors Precipitation changes

3)What makes a species invasive? c) Environmental 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 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: : 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 Change Hypothesis Global Change Factors Increasing atmospheric CO 2 Increasing N deposition Global warming SUMMARY: Global Changes General response is similar to that observed for elevated CO 2 Evidence in some specific cases But not all invasives benefit Precipitation changes and N deposition hypotheses relate to the ‘resource abundance’ hypothesis (next week)