Calif., on grass and shrub sites within the pon- 
derosa pine bunchgrass area, Lassen National 
Forest, Calif. (Carneggie and Reppert 1969). A 
second study was started at Black Mesa on 
sites within the high-elevation Thurber fescue 
grassland, Gunnison National Forest, Colo. A 
third was on shrub sites used primarily as deer 
winter range in Middle Park, Colo. 
In 1968, two more studies were started: one 
in a pinyon juniper area near McCoy, Colo., and 
another on sites within the ponderosa pine 
bunchgrass area at the Manitou Experimental 
Forest, Colo. 
Preflight ground procedures consisted of 
marking certain plant species and _ other 
ground features with arrows (surveyor stakes 
laid horizontally on the ground) for quick 
comparative reference on aerial photographs 
(fig. 1). Rectangular plots were laid out, and 
the vegetation therein was mapped or photo- 
graphed from the ground for future compar- 
ison with aerial photographs. Line-chart in- 
tercept of vegetation, and other ground fea- 
tures along transects within these plots, were 
measured for comparison with the scan-line 
output of image color densities produced by a 
microdensitometer. This instrument, which 
measures light transmission through photo- 
graphic transparencies, is affected by the 
image density of small areas; it is described in 
more detail by Doverspike et al. (1965). The 
ground targets were photographed from a step- 
ladder at or near the time of flight, and exten- 
sive notes were taken about plant phenology, 
plant and soil colors, and other factors (fig. 2). 
The aerial photographs were taken from an 
Aero Commander 500B by personnel of the 
FiGuRE 1.—Photo from a stepladder, showing arrows 
pointing to four species, bare soil, and a rodent bur- 
row entrance. Long lath on right points to zero end 
of a 20-foot permanent line transect; 10 feet of this 
transect is shown in the photograph. 
FIGURE 
marked targets are taken on or near the day of the 
photo mission, and make up a vital part of the 
ground truth. Note low-flying photo plane. 
2.—Near-vertical ground photographs of 
Forestry Remote Sensing Project, Pacific 
Southwest Forest and Range Experiment Sta- 
tion, Forest Service, U.S. Department of Agri- 
culture, Berkeley, Calif. Twin-mounted KB 8A 
Maurer cameras, equipped with 150-mm. 
Schneider Xenotar lenses, were used with 70- 
mm. Anscochrome D-200 filtered with a 1-A 
Skylight filter, and with Ektachrome Aero In- 
frared with a Wratten 12 filter. The cameras 
were impulsed simultaneously with an Abrams 
CP-3 intervolometer to provide identical photo 
coverage on the two film types. Shutter speeds 
were set at 1/2,000th second, with the airplane 
flying 100 miles per hour, to reduce image mo- 
tion and to obtain 60-percent overlap for ster- 
eoscopic coverage. The photo missions were 
flown rather close to the ground, some as low 
as 300 feet, to obtain the large scales desired. 
EARLY RESULTS 
Several results have been obtained from this 
first work. Obtaining large-scale color aerial 
photographs was not an end in itself. In fact, 
if aerial photographs are taken without regard 
to season, they may be nearly unusable for de- 
sired objectives (see color plate II D and E in 
accompanying paper by D. M. Carneggie). 
However, if the necessary time is first ex- 
pended to find out why things are happening to 
features shown on the photographs, one can 
then hope to prescribe situations when color or 
color infrared aerial photography will be use- 
ful. 
The best time or season for photography de- 
pends upon what range feature is of interest 
and its stage of development, if it is a plant. 
For example, at Harvey Valley, Calif., in late 
July, both color and color infrared film were 
good for identifying Eriogonum spp., which at 
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