The Ratio of Shoot Silhoutte Area to Total Needle Area in Sctos Pine

Washington D.C.

1988

S. 894-906

8 Abb., 2 Tab., 15 Lit. Ang.

Bandaufführung

7380

16060

The dependence of light interception efficiency on shoot structure was studied. The silhouette areas of 258 Scots pine (Pinus sylvestrisL.) shoots inclined at different angles were measured and the corresponding si lhouette area to total needle area ratios (STAR) were determined. For each shoot, a mean silhouette to total needle area ratio (STAR) with respect to a spherical shoot orientation was calculated. STAR varied between 0.090 and 0.21 and averaged 0.14. For spherically oriented individual needles or leaves, the corresponding mean projection of unit foliage area is 0.25. Thus, the light interception efficiency of the shoots as indicated by STAR- values was on average reduced by 43% because of mutual shading of needles on the shoots. The silhouette areasand STAR-values were also calculated theoretically using a previous model of s hoot geometry, and these values were compared to the empirical measurements.