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Ecology: Lecture 3Ecology: Lecture 3
Plant adaptations to the light environment (Physiological Ecology)
PAR: Photosynthetically PAR: Photosynthetically active radiation (400-740 active radiation (400-740
nm)nm)
P-I CurveP-I Curve
PhotoinhibitionPhotoinhibition
Photosynthesis: reviewPhotosynthesis: review
Photosynthesis: Photosynthesis: light-dependent light-dependent
reactionsreactions What do these
reactions accomplish?
Photosynthesis: Photosynthesis: light-light-inindependent dependent
reactionsreactions What do
these reaction accomplish?
Role of rubisco?
Benefit vs. cost of Benefit vs. cost of rubisco reductionrubisco reduction
Changes in leaf orientationChanges in leaf orientation
Shade-tolerant vs. intolerant Shade-tolerant vs. intolerant plantsplants
Terrestrial Aquatic
Responses to UV Responses to UV radiationradiation
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 Plant defenses against UV-BUV-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?