APPENDIX 



SURVEY PROCEDURE 



The forest survey of the Anthracite Forest Region is 

 the first large-scale survey in which forest area, forest 

 condition, and timber volumes have been estimated 

 in detail directly from aerial photographs. (These 

 estimates were supported by field checks.) Most of 

 the photographs used were made for the Agricultural 

 Adjustment Administration between 1938 and 1940. 

 Contact prints on a scale of 1 :20,000 (slightly more 

 than 3 inches per mile) and aerial photo index sheets 

 on a scale of 2 inches per mile were used. 



Forest Area Estimates 



forest areas were estimated from aerial photo index 

 sheets on which the minor civil-division boundaries 

 had been delineated. This was done by means of 

 celluloid overlays marked with small evenly spaced 

 dots. The overlays were placed over the index 

 sheets, and the dots falling on forest and nonforest 

 areas within each civil division were counted. The 

 forest area was figured by applying the proportion of 

 dots falling on forest area to the gross area of the civil 

 division as given by the 1940 Census of Agriculture. 



The number of dots or samples taken within each 

 civil division was designed to yield forest area esti- 

 mates within ±10 percent based on two standard 

 errors. Celluloid grids with adequate numbers of 

 dots per square inch were used to assure attaining 

 this standard. Empirical cheeks indicate that the 

 statistical accuracy of the sampling method used is 



considerably better for forest area estimates than ran- 

 dom sampling using the same number of samples. 

 Interpretation of forest areas on the aerial photo 

 index sheets may be less accurate than the range o\' 

 error indicated statistically. Reference was made to 

 the contact prints in cases of doubtful interpretation, 

 and the forest area estimates were carefully checked 



by more than one individual. Because- the county 



lorest area figures are (he summation o( those for 



minor civil divisions they are probably more accurate. 12 

 Records were also made of the number of samples 

 falling in tracts less than 10 acres in size, those in to 

 50 acres, and those 50 acres and over. The proportion 

 of the samples falling in each classification were ap- 

 plied to the forest area figures to obtain the respective 

 acreages. 



Mine-waste areas were estimated through the use 

 of acreage grids. Cropland and water areas were 

 determined from the 1940 census. 



Planimetric base maps were prepared from United 

 States Geological Survey quadrangles or State high- 

 way department maps showing the principal roads 

 and highways, streams, lakes, and cities and towns. 

 Land use maps were prepared from these b) super- 

 imposing forest areas of 3 acres and larger, mine 

 waste banks, open land, and urban areas. 13 



12 Detailed county estimates are given in the Following publications: 



\i>KIIII\SIIK\ tciRl SI I'M' I KIM INI Si \ 1 I.'N. 



1945. THE FOREST SITUATION IN PIKI \ rtheast. 



Forest Expt. Sta. Anthracite Survey P ! pp.. illus. 



[Processed. | 



1945. nil FOREST SITUATION 1\ DAUPHIN vsp LEBANON 



east Fon Anthracite Survej Paper 8. 30 pp.. illus. 



[Processed.] 



I'l< k i si sin ITION IN SCRUYLKILI IND CARBON < I \ I 



east. Foresl Expt. Sta. Anthracite Survej Paper . 34 pp., illus. 

 issed.] 



1946. THE FOREST SITUATION IN WYOMING AND SULI4VAN < ' \ 



east. Forest I tp Si Anthracite Su ' pp.. 



illus. [Processed.] 



II' mm POKES1 SITUATION IN NORTHUMBERLAND, COLUMBIA 



» counties Noi thi ist. 1 Sta. A 



Papei 1 1 18 pp., illus. [Pi ectsed.l 



lit I III I .'Kl si sin ITION is l I 



\ rtheast. Forest Expt. Sta. Anthi v 



illus. [Pi 



1946. TH X IN WAYNE AH 



Northeast. Forest Expt. S \ 

 illus. [Processed.! 



|J Land u« i l inch 1 mi 



ties in the Anthi.i. I gion. Tlir\ 



S Dit . \\ 



The Anthracite Forest Region A Problem Area 





