COMPARISON OF RESURVEY WITH INITIAL SURVEY 



Some of the most significant information forest survey data can show is 

 trends. Comparison of growth and drain data throw seme light on trends 

 but in the long run the most revealing comparisons will be between suc- 

 cessive inventories. However, two circumstances limit the comparisons 

 which can be made between the original forest survey in North Idaho and 

 this resurvey. One is that a generally tightening wood supply situation 

 has resulted in more critical standards. For example, a considerable 

 area that was once classified as noncommercial has now, because of im- 

 proved economic conditions, become commercial. The other circumstance 

 is the change of standards made to conform to revised nationwide defini- 

 tions so that data from the various regions will be comparative and addi- 

 tive. For example, the minimum size for some species of sawtimber trees 

 in this region formerly was 13.0 inches d.b.h. The minimum size for all 

 species is now 11.0 inches. The minimum volume for sawtimber stands was 

 reduced from 4,000 and 3,000 board feet per acre Scribner rale to 1,500 

 board feet per acre International l/4-inch rale. 



Some broad adjustments have nevertheless been made in the initial forest 

 survey data to make them as comparable as possible with the resurvey. 

 The most important adjustment in the initial survey data was the reclassi- 

 fication of 910,000 acres from the noncommercial to commercial category. 

 Developments in logging and transportation equipment and increased value 

 of wood products make this area presently or potentially operable. Tables 

 1 and 2 on pages 9 and 10 summarize these comparisons. 



The differences between the adjusted initial survey and the resurvey so 

 far as total forest area and commercial forest- area are concerned are 

 less than the sampling error limits of the resurvey. Thus the data in 

 themselves indicate no trend. However, the survey transects showed some 

 conversion of commercial forest to cropland and virtually no reversion 

 of cropland to forest. Hence, there has probably been a very small re- 

 duction in forest area. 



The differences between the two surveys in area figures by stand-size 

 classes likewise is less than the sampling error limits. However, for 

 all types as a group, it is believed that the cutting of sawtimber stands 

 has been offset by the transition of pole stands into sawtimber size. 

 Because of the disproportionately heavy out of white pine and ponderosa 

 pine the sawtimber area of these types has undoubtedly shrunk. 



The resurvey shows a higher proportion of deforested land than was indi- 

 cated in the initial survey before adjustment. This is because a large 

 part of the area reclassified from noncommercial to commercial is de- 

 forested. Also, the resurvey has tallied numerous small openings 

 "washed in" with other stand classes in the initial survey. When ac- 

 count is taken of these factors it appears that the deforested area has 

 actually decreased. The deforested area, nevertheless, is very large 

 and constitutes an obstacle to continued high level production. Much 

 of it is potentially high yielding white pine land. Some of the defor- 

 estation dates back to 1910 which indicates the land is not restoring 

 itself very rapidly. 



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