Leaf surface area present on black cottonwood (Populus trichocarpa) and
Douglas hawthorn (Crataegus douglasi) was measured indirectly using a point
frame, photographs, and a canopy analyzer. Each was compared to directly
measured leaf surface area. Six black cottonwood and 3 Douglas hawthorn shrubs
were selected in 1996 and 9 black cottonwood and 3 Douglas hawthorn shrubs in
1997. Shrubs were selected based on size and isolation. Each indirect method was
applied prior to removing a portion of leaves from each shrub. Shrubs were
defoliated in 3 to 7 increments and leaf surface area of each was measured. After
shrubs were completely defoliated increments of measured leaf areas were added to
subsequently removed leaf areas to determine the measured leaf area present on a
shrub each time indirect methods were applied. Measured leaf areas were paired
with indirect method values and regression equations were developed. Correlation
coefficients for regressions were 0.76 for black cottonwood and 0.70 for Douglas
hawthorn for the point frame, 0.91 for black cottonwood and 0.79 for Douglas
hawthorn for the photographs, 0.62 for black cottonwood and 0.61 for Douglas
hawthorn when shrub volume was included for the canopy analyzer. Photographs
took 20 minutes to set up and take pictures followed by 1.5 hours for processing
images in Idrisi and Picture Publisher. The point frame required 45 minutes to 1.5
hours field time and 5 to 10 minutes to process data. The canopy analyzer was the
most rapid of the techniques requiring less than 5 minutes to secure a field
measurement and enter this value into the regression equation. Canopy analyzer
reliability was the lowest of the methods studied. / Graduation date: 1999
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/36755 |
| Date | 10 March 1999 |
| Creators | Reynolds, Mark P. |
| Contributors | Johnson, Douglas E., Krueger, William C. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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