140
J. 1 ) . OVINOTON
Primary production
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0
25
SO
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- Contained in ecosystem
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50
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50
L f lo] :emwed in h a m s
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- 8 0
- Q
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Age of trees (years)
FIG. 6. Energy budget for plantations of Pinus q h e a t r i e
from time of planting.
The magnitude of energy flow through the series of Scots pine woodlands referred to earlier (Ovington, 1961) has been determined by
calorimetry. During the 55-year period following tree planting, the
primary net production per h a contained just over 422 x 1O1O cal,
equivalent to a mean annual transformation of solar energy of about
8 x 1010 cal, of which just over three-quarters can be attributed t o the
trees (Fig. 6). At the peak period of organic matter production when
the trees are essentially the sole primary producers, the annual fixation
of energy in the net primary production is 10 x 1010 cal per ha. Since the
average annual income of solar radiation t o the pine plantations is
about 770 x 1010 cal per ha of land surface, about 1.3% of the incident
energy is stored within the primary products of photosynthesis, and