volume are not necessarily the best for estimating net board-foot volume, and may be weak in 

 selecting acres of high risk timber or acres where thinning is needed. In a single limited study 

 it is hardly possible to test the value of the many photo-stratification schemes for all types of 

 data collected in volume and management inventories. However, it is possible to evaluate a 

 number of photo or field stratification schemes by means of indices based on one or two types 

 of data collected. 



The purpose of this paper is not to outline a survey plan, but rather by evaluating a num- 

 ber of photo- stratification schemes, to provide a reasonable basis for selection of a scheme 

 when considering photo stratification in timber cruising or combined forest management volume 

 inventories . 



The question to be answered is: Which classification scheme uses this available aerial 

 photo information most effectively in stratifying forest stands for combined forest management 

 and volume inventories? 



During the 1960 field season the Intermountain Forest and Range Experiment Station, in 

 cooperation with other Stations and Regions of the U.S. Forest Service, conducted the St. Regis 

 study- -a pilot test of a new survey procedure designed to collect basic information to satisfy 

 both inventory and management needs. This was primarily a field study; however, the ground 

 plots measured for this test were also measured on aerial photos and these paired plots 

 furnished the basic data used in this study of aerial photo-stratification schemes. 



OBJECTIVES 



In general we wanted to know which aerial photo- classification scheme would contribute 

 the most in a combined forest management -volume inventory. 



Specifically we wanted to: 



1 . Evaluate the several methods of photo or map stratification by their ability to in- 

 crease the efficiency of the estimates of cubic- and board-foot volume. 



2. Rank the methods by their ability to segregate areas of high risk sawtimber and 

 young stands needing thinning or other management treatment . 



3. Determine which method would best combine these management and volume 

 inventory aims . 



4. Estimate the saving in cost possible by use of this method. 



THE STUDY 



For this study we had available 126 1-acre plots systematically located throughout a 

 132,000-acre unit in the St. Regis Ranger District of the Coeur d'Alene National Forest, 

 Montana. These plots were first measured and classified on aerial photos and then on the 

 ground during the 1960 field season. 



Nominal l:16,000-scale 85-inch focal length USDA photos flown in 1958 were available for 

 the area. Recent 1 :62 , 500-scale USGS quadrangles with 80-foot contour intervals were also 

 available. Mean flying height and photo-scale reciprocals were determined for 200-foot 

 elevation changes from 68 scale lines measured on the maps and photos of the area. 



3 



