Estimation of leaf area with an
integrating sphere
Recently ,there goes the saying of
estimation of leaf area with an integrating sphere,the article will give a
detailed introduction for this estimation saying. Please read the following
sentences carefully ,and hope you can get something from them.Relative
absorptance of intact branches measured with integrating sphere was compared to
leaf area estimated by the commonly used methods (volume displacement and
scanning area meter) for three conifer species:Picea mariana (Mill.) BSP, Pinus
banksiana (Lamb.) and Pseudotsuga menziesii (Mirb.) Franco. A consistent
relationship between relative absorptance and surface area came out for the
three species. The ability to predict leaf area from absorptance was further
explored by measuring branches of Pseudotsuga menziesii grown in varying light
and nutrient regimes. When a single equation was used to predict leaf area
under all growth conditions, errors were as large as 40% primarily because of
variation in leaf absorptivity, with the largest errors associated with extremely
nutrient-deficient foliage. When separate empirical equations were developed
for each growth treatment, predicted leaf surface area agreed to within 5% of
the area determined by the volume displacement method. Leaf surface area
estimated from theoretical principles was also in good agreement with total
surface area estimated independently by conventional methods. With proper
accounting for needle absorptivity, which varied with growth conditions, leaf
area estimates obtained by the integrating sphere method were of similar
accuracy to those obtained by conventional methods, with the added advantage
that the method allowed intact foliage to be sampled nondestructively in the
field. Because the integrating sphere method protects branch structure in the process
of measurement, it could provide a useful measurement of needle area for
photosynthetic or developmental studies requiring repeated sampling of the same
branch.
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