carbon cycle Flashcards
GPP?
ross Primary Production (GPP): ecosystem-level photosynthesis
Photosynthesis – conversion of atmospheric CO2 to carbon products by plants
CO2 + 2H20 + light energy à CH20 + H20 + O2
calvin cycle?
Calvin cycle: Light independent cycle – energy molecules to fix carbon dioxide
molecules
How does nitrogen affect growth?
Provide budling blocks to build photosynthetic enzyme
what controls productivity
net photo
pp at an ecosystem level
Net photosynthesis by leaves (leaf level)
) Light
b) Nitrogen
c) Water
d) Temperature
e) CO2
primary productivity
Primary Productivity (GPP & NPP) (ecosystem level)
a) Leaf area
b) Seasonal length
how do planta adapt to light limitation
plants can respond via acclimation – physiological responses to the environment and adaptation
– change of population in allele frequency
look at light graph
ok
slope for light graph?
Slope = photosynthetic light use efficiency (LUE)
Steeper slope = increased photosynthetic per unit of light (LUE)
light saturated?
Light saturated = # of chloroplasts are maximized
- Increase of light = excess photons creating free radicals which degrade
thus decrease photo-oxidation (photosynthesis)
top canopy leaves?
Top canopy (lots of light) has smaller thick leaves to withstand radiation where shade leaves are
thick and big to absorb light radiation
- Because access to light is limiting thus they don’t allocate as much
energy to enhance capture of those photons and concentrate energy to
provide more photosynthetic structures
- Top leaves reduce the surface area to enhance heat balance in leaf
rubisco?
Rubisco – an enzyme used my primary producers to convert CO2 into organic compounds (light
compensating for carbon that is lost in oxidization)
how is photosynth measured?
Photosynthesis is measured by microcopy through wavelength of activity.
- Shade leaf is equally active at all wavelengths. Light that is hitting
leaves is narrow because top leaves absorb some waves
- Top canopy leaf is most active with blue wavelength. Light that
reaches canopy is a broader spectrum thus it is beneficial to have all
wavelength photons.
what is shade tolerance? factors?
Shade tolerance: ability of a plant to tolerate low light levels
- Light spectrum is niched
- Photosynthesis increases over a wider range of light levels
- Light saturation = Isat
- Summation of species creates a broader Isat for the community
- The Isat is different for each species, but the community shows a broader Isat
level, thus plants maximizing by their own different levels = summation of
species. Enhances by plants being varied in their light responses
