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1952
ANGE
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(665)
photographs than do range inventories because of the single crop method of
culture. Fields are predominately planted to one crop, laid out largely on geo-
metric patterns, and involve less variety of outline than do range areas. Row
crops are readily distinguishable from crops which have been closely drilled,
and which present an appearance of even cover. Hay fields during or after
harvest are readily recognized by the harvesting operations, or by the haystacks
after the harvest season. Prior to harvesting, such areas are not readily distin-
guishable from level grassland or fields of grain.
Bringing the topography into relief often distinguishes grassland from hay
or grain fields by the steepness of slope or the presence of furrows, irrigation
or other cultivation marks. However, details of the varieties of grain, hay or
row crops must ordinarily be determined by check on the ground.
Ordinary culture, buildings, fences, ditches, dams, roads, trails, railways,
tramlines, mines and other man-made improvements are usually discernible
from good photographs, and their location from these greatly reduces the time
necessary to locate them by ground survey methods. When these are obscured
by trees or other vegetation, ground surveys must supplement the photographic
determinations.
In range inventory, various types are classified according to their aspect
as they appear to the examiner on the ground. Certain types are distinct, both
on the ground and on photographs. Timbered and nontimbered areas, big
browse, broadleaf trees, meadows and rough rock are usually distinct. Others
have much similarity of appearance. Grassland, light-colored or smooth rock,
sagebrush, dry weeds, sand bars and gravel beds having common light color
tones appear very similar on a picture. Young and old timber are readily
separable. Mature trees can often be recognized by species. Ground examination
is essential to differentiate between species of grasses and weeds and for various
species of shrubs and trees. Clear-cut demarkation lines between trees or shrubs
and grassland, for example, may or may not be the true dividing line as found
on the ground. Forage cover extent is determined by the herbaceous or shrub
cover principally. This frequently extends into the edge of the timber and may,
in the aggregate, include a significant amount of forage which, if the pictured
outline were strictly followed, might be included as timbered, nonproductive
range land.
Browse and grass are usually easily differentiated. Tall-growing shrubs
like willows, alder and mountain maple are readily separated from low-growing
kinds by their growth form, photographic tone, and habitat.
Verification on the ground of essential differences in habits of growth,
characteristic shapes, depth and differences of color as shown by the shade and
tone of the picture, shadows cast by the vegetation, growth site, presence of
water, desert conditions, alpine or subalpine elevations, and timber line, all
assist in reaching tentative conclusions on vegetative cover.
A majority of range inventories are made on wild land which has not been
extensively altered by human occupation. On such sites, characteristic situations
and cover are often repeated on certain sites. Recognition of site characteristics
is, therefore, an important element of assistance. A full knowledge of the flora
in the region to be inventoried is an essential prerequisite.
Many large areas appear identical in the pictures. Examination on the
ground will disclose many differences in forage species and cover which must
