Appendix C.   SSC Canopy-Closure Data (%shade)

Plot# 99-by-eye 03-camera 03-by-eye Densiometer Lux-Rank
Plots treated by thinning trees
20 00 17 05 35 06
T4 00 40 00 68 14
10 00 49 00 47 03
11 05 39 00 59 01
14 25 60 00 60 13
17 40 62 20 60 09
18 50 61 60 51 02
13 50 74 40 47 05
06 50 74 60 67 08
16 50 79 10 51 15
15 60 57 00 60 07
12 75 72 80 48 04
Untreated Control plots
T3 50 81 40 64 16
02 75 78 70 67 20
04 75 82 80 55 18
07 75 82 80 69 11
T2 75 85 70 71 22
19 90 70 60 77 12
05 95 75 75 58 10
09 95 84 80 54 17
08 99 78 90 76 21
T1 99 80 50 65 19
03 99 83 75 61 23
01 99 90 40 67 24

Note: all values are in percent-shade, except for the Lux-Rank column (see below).

The "99-by-eye" estimates of canopy-closure were done by Bud Ewacha and Richard Reeves.
The "03-by-eye" estimates were done by Doris Ames.

The "camera" estimates involved taking a wide-angle photograph from ground-level pointing straight up, on a cloudy day, using a digital camera with a moderately wide-angle lens (a 35mm lens, when expressed in 35mm-camera-equivalent terms). These photographs were then analyzed algorithmically, by converting each to a Black & White image of 30,000 pixels, then computing percent-shade as the number of black pixels over 30,000. Photos and analysis done in 2003 by Eugene Reimer.

The "Densiometer" readings were taken in 2003 with a Model C (concave) Forest Densiometer from Robert E. Lemmon of Bartlesville OK; at each location we took 4 readings facing in 4 directions and averaged them; reported here is the average of 2 sets of such results done by Doris Ames and Eugene Reimer.

The "Lux" readings were taken with an Optikon Hagner model EC1 luxmeter, in 1999, 2000 and 2002. Shown here is only their ranking, where 01 is the brightest, 02 the 2nd brightest, and so on. (The actual readings are shown in a separate table, elsewhere in this report.)

Results:

The study site was a very dense cedar forest in 1997 prior to the cutting. Then in 1997 and 1998 some trees were cut and removed, so as to increase the light-levels. Plots were laid out in 1999; originally they were divided into 4 groups, by the degree to which they had been affected by tree-removal. However due to conflicting results from our different ways of measuring the degrees of treatment, and due to some doubt about how uniform the conditions were prior to the cutting, we are now dividing the plots into only 2 groups, namely:
Control plots - those largely unaffected by the cutting, and
Treated plots - those receiving significantly more light as a result of cutting.