Photosynthesis of Vascular Plants
I:
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-<
E
:l
E
x
c
E
......
0
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Elymus repens
100
80
,/if
I
60
I
40
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0 May
20
• June
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October
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0
Pueeinellia distans
100
80
60
40
20
o~~--~---L--~--~~~~--~
o 5 10 15 20 25 30 35 40
Canopy height after simulated mowing, em
421
Fig. 20.7. Calculated relative
changes in canopy net photosynthesis (A can) of Elymus repens and Puccinellia distans in
response to simulated mowing
(see text) in mid-May, midJune, and mid-October 1989.
(Beyschlag et al. 1992)
20.5 Canopies with Nonhomogeneous Structure: Radiation Fluxes
in Three Dimensions
Nonhomogeneous canopies occur where vegetation is substantially clumped
and/or discontinuous in structure. Calculation of light interception and
photosynthesis for the different elements of such canopies is necessarily
much more complicated than for homogeneously structured canopies. The
primary difficulty is that the light interception of a plant growing in such a
canopy is affected by surrounding vegetation which may be present at
various distances in different compass directions from the plant in question.
In addition, light may reach the plants from the sides as well as from above
and, thus, a three-dimensional modeling approach is needed.