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Timothy J. Gardner and T. Davis Sydnor

Abstract

Five species of ornamental trees were examined with an Eppley pyranometer for interception of total solar radiation between 380 nm and 1100 nm. Measurements were made at the northern dripline and expressed as percentage of shade. Trees were selected for varying forms, branch, and canopy densities. Mean percentage of shade for the fully foliaged and leafless canopies, respectively, were Pyrus calleryana ‘Chanticleer’ 75% and 43%, Acer rubrum ‘Red Sunset’ 69% and 25%, Zelkova serrata ‘Village Green’ 61% and 24%, Gymnocladus dioicus 60% and 15%, Gleditsia triacanthos inermis ‘Moraine’ 56% and 21%. No statistically significant (PSO.05) correlation was observed among solar radiation intercepted and photosynthetically active radiation (PAR) intercepted, pathlength, silhouette area, and canopy volume. Growth habit did not affect shading capacities significantly.

Open access

Timothy J. Gardner and T. Davis Sydnor

Abstract

Photographs of five fully foliaged shade tree canopies (Acer. rubrum, Gleditsia triacanthos inermis, Gymnocladus dioicus, Pyrus calleryana, and Zelkova serrata) were taken using four film types, 50- and 28-mm lenses, and a range of three f-stops. Photographs of four leafless shade tree canopies (Gleditsia, Gymnocladus, Pyrus, and Zelkova) were taken using three film types and two lenses, at two f-stops. Film densities were determined with a light source and quantum sensor system for negatives of fully foliaged and leafless canopies and correlated with mean percentage of shade measured with a pyranometer. Pan-X film, at the correct f-stop setting, gave the highest correlation to mean percentage of the fully foliaged canopies. The 50-mm lens gave a higher correlation than the 28-mm lenses. Plus-X film, at an f-stop one above the proper setting, gave the highest correlation to mean percentage of shade of the leafless canopy. Plus-X film produced the most consistent results when photographs of the leafless canopy were taken during different days and times of the day. Using a densitometer to measure film density of the negatives gave high correlations to mean percentage of shade of the leafless canopy.