Ecology: Lecture 3 Plant adaptations to the light environment (Physiological Ecology)

PAR: Photosynthetically active radiation ( nm)

P-I Curve

Photoinhibition

Photosynthesis: review

Photosynthesis: light-dependent reactions   What do these reactions accomplish?

Photosynthesis: light-independent reactions  What do these reaction accomplish?  Role of rubisco?

Benefit vs. cost of rubisco reduction

Changes in leaf orientation

Shade-tolerant vs. intolerant plants Terrestrial Aquatic

Responses to UV radiation  What is the relationship between the ozone layer and UV-B?  What are the consequences of UV-B exposure to primary producers?  DNA damage, change in growth form, reduction in yield  Example: In situ studies in the Antarctic ozone hole (1990) suggest a reduction of 6-12% of primary production due to the ozone hole

Plant defenses against UV-B  Compounds that absorb UV-B  Effects on photosynthesis?  Tropical and alpine plants are more capable of blocking UV-B radiation  Does this make adaptive sense? How so?  Plants with short-lived seasonal leaves were less effective at blocking UV-B rays.  Does this make adaptive sense? How so?