12 PHOTOGRAMMETRIC ENGINEERING
classification and subsequent field measurement of sample plots with little or.
no actual mapping.
In general, few foresters have training or experience in quantitative interpre-
tation; many use some form of qualitative interpretation, while others have pro-
gressed no further in their use of photos than to consider them as a glorified
form of field map sheet. Equipment in use varies all the way from a lens stereo-
scope to the Multiplex, though emphasis is still on the less complicated and least
expensive types. :
CONCLUSIONS
1. The history of aerial photos in forest inventory can be traced through the
publications of the past 30 years. It shows that many of the present interpreta-
tive techniques were visualized by early pioneers.
2. The forest can be classified and measured on photos by a mapping pro-
cedure or a sampling procedure. Both make use of the same qualitative interpre-
tations.
3. Most forest inventories require some field work but the number of field
plots needed can be greatly reduced by quantitative interpretation using aerial
volume tables. On reconnaissance-type forest inventories, field work may not be
needed if adequate aerial volume tables are available.
BIBLIOGRAPHY
Andrews, L. A. 1921, “The Aeroplane’s Service to Forestry,” Canad. Forestry Mag., 17: 419-422
Colwell, R. N., 1946, “The Estimation of Ground Conditions from Aerial Photographic Interpreta-
tion of Vegetation Types," PHOTOGRAMMETRIC ENGINEERING, 12: 151-161.
Harrison, J. B. D., 1950, “Planning a National Forest Inventory,” Forestry Division, Wood and
Agriculture, Organization of the United Nations, Washington, D. C.
Jensen, C. E., 1948, “Dot-type Scale for Measuring Tree-Crown Diameters on Aerial Photo-
graphs,” U. S. Forest Service, Central States Forest Experiment Station, Note No. 48.
Jensen, H. A., 1947, “A System for Classifying Vegetation in California,” California Fish and
Game, 33: 199-266.
Jensen, H. A. and R. N. Colwell, 1949, ‘““Panchromatic Versus Infra-red Minus-blue Aerial Photog-
raphy for Foresty Purposes in California,” Jour. Forestry, 47: 340-341.
Lewis, Lieut., 1919, “Photographing Forests from the Air, Canad. Forestry Jour., 14: 110-112.
Nakayama, H., 1935, “Stocking of Forests from Air Photographs," Forestry Chron., 11:(3) 48-49
Rogers, E. J., 1946, “Use of the Parallax Wedge in Measuring Tree Heights on Vertical Aerial
Photographs," U. S. Forest Service, Northeast Forest Expt. Sta., Forest Survey Note No. 1.
Seely, H. E., 1934, “Aerial Photography in Forest Surveys," Empire Forestry Jour., 13: 244—247.
Seely, H. E., 1949, “Symbols for Description of Growing Stock on Maps of Air Photos," Forestry
Chron., 25: 62—65.
Spurr, S. H., 1946, ‘Volume Tables for Use with Aerial Photographs,’ Harvard Forest, Petersham,
Mass.
Wilson, Ellwood, 1926, “The Value of Aerial Survey in the Study ot Forest Conditions,” First j
Internatl. Silvic. Conf. Proc., 3: 222-237.
Wilson, R. W., 1950. “Controlled Forest Inventory by Aerial Photography,” Timberman., 51:(4)
42-43, 98.
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