Forest Types 



Forest types were mapped by field reconnaissance, 

 supplemented by the use of aerial photographs. 

 Automobile reconnaissance was employed to map 

 areas available from roads, while reconnoitering by 

 foot was used for mapping types in areas not visible 

 from roads. Aerial photographs helped in the 

 delineation of type boundaries. Summer-exposed 

 photographs were used in the delineation of scrub oak 

 areas. Some winter photographs were available for 

 use in separating conifers and hardwoods for a portion 

 of the region; field checks were made to determine 

 species. 



Fourteen forest types were recognized within the 

 region but only seven of these were found in areas large 

 enough to justify mapping for this report. The areas 

 dominated by these seven types include small areas of 

 other types. 



Forest Condition Classification 



All saw-timber and pole-timber stands 10 acres and 

 larger were delineated on aerial photo contact prints 

 by means of stereoscopic examination. All such 

 stands estimated to have 2,000 board feet or more 

 (International %-inch rule) on each acre were classi- 

 fied as saw-timber stands; those other stands having 

 at least 400 cubic feet on each acre, or 5 cords, were 

 classified as pole-timber stands. All other stands were 

 considered as unmerchantable. Estimates of volume 

 per acre were made by determining the average height 

 of trees and the average number per acre for each 

 stand and applying a volume table based on total 

 height. Tree heights were estimated from aerial 

 photos by measuring shadows cast by trees on level 

 ground and multiplying these measurements by the 

 tangent of the angle of the sun's rays with the earth 

 at the particular moment the picture was exposed. 

 The number of trees per acre was estimated by 

 counting the visible crowns contained within Js-acre 

 templets placed on the photographs. 



Maps showing the location of each saw-timber and 

 pole-timber stand 10 acres and larger and the un- 

 merchantable stands were prepared for each of eight 

 counties: Lackawanna, Pike, Monroe, Schuykill, 

 Northumberland, Montour, Dauphin, and Lebanon. 14 

 Tabulations were also prepared of the area, estimated 

 volume per acre, and the estimated total volume of 

 each merchantable stand. 



14 These maps may be ordered from the U. S. Forest Service, Division of 

 Engineering, Washington 25, D. C. 



Volume Estimates 



Volume estimates for each saw-timber and pole- 

 timber stand were made for these eight counties 

 and the sum of these was used for total county 

 volumes within these condition classes. Estimates 

 were made from aerial photographs in board feet for 

 saw-timber stands and in cubic feet for pole-timber 

 stands. Forty check tracts ranging from 10 to 500 

 acres were cruised in the field for each of the first 

 3 counties and 40 for the remaining 5, a total of 160 

 tracts equally apportioned among saw-timber and 

 pole-timber stands. Intensity of cruises varied from 

 50 to 5 percent, the greater intensity in the smaller 

 areas. These indicated that the volume-per-acre 

 estimates from the aerial photographs were within 

 20 percent of the field check 8 times out of 10 and 

 that as a result of compensating errors the total 

 estimate for each group of 20 tracts was within ±5 

 percent of the field check. 



Cruise data from the check tracts were used as a 

 basis for estimating the volume of the understory in 

 saw-timber stands and the volume of saw timber in 

 pole-timber stands. Empirical estimates were made 

 of volumes in the unmerchantable areas. 



Species Composition and Diameter-Class 

 Distribution 



Stand and stock tables showing the numbers of 

 trees and the cubic-foot and board-foot volumes of 

 each species for each of the major forest types and 

 condition classes were compiled from systematically 

 selected field data. The records for 50 %-acre sample 

 plots in each of the major forest type and condition 

 classes, distributed among the counties on the basis 

 of the relative occurrence of the classification area, 

 were used. The resulting stand and stock tables 

 were used as a basis for allocating volume data to 

 the various species and species groups and to diameter 

 classes. Local board-foot and cubic-foot volume 

 tables were developed for the trees of the Anthracite 

 Forest Region. 



Growth Determination 



Measurements for growth calculations were ob-> 

 tained from increment borings made in the line-plot 

 survey, supplemented by additional borings. The 

 growth rates for a 10-year period by species and 

 2-inch classes were determined mathematically, andi 



56 



Miscellaneous Publication 648, U. S. Department of Agriculture '< 





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