Efficiency of Net Primary Production Based on Light Intercepted During the Growing Season
1968
Botkin, Daniel B. | Malone, Charles R.
Net primary production of a 1—year—old field on the New Jersey Piedmont was 1.08 kcal/cm² or 10% of the radiant energy (0.4—0.7 @m) intercepted by the vegetation from the last spring frost to the latest date a dominant producer reached its peak standing crop biomass; 3.8% of the energy available above the vegetation during the same period; 7.5% of the energy intercepted from the last spring frost to the first fall frost; 3.1% of the energy available above the vegetation during this period; and 1.8% of the energy available yearly. These results are among the first direct determinations of efficiency of net primary production based on interception of radiant energy under field conditions. Interception, the difference between radiant energy available above and below the vegetation, was measured with the Yellott solarimeter, whose small size made possible below—vegetation measurements with minimum disturbance to the cover. Net primary production for shoots was determined on a species basis by the short—term harvest method. Root production was estimated on a community basis by extracting roots from soil samples by a soil—dispersion and chemical flotation technique.
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