912 JOURNAL OF 1-OkKSTRV 



CUTTING DISEASED TREES 



The extra cost of felling diseased trees is an item which has not been 

 worked out very completely for District 5. In connection with the snag- 

 disposal study on the Plumas National Forest, a time study of timber 

 felling was conducted on 75 trees, with an average diameter breast high 

 of 40.75 inches. 



The following table has been worked up from curves based on the 

 data collected : 



Time of Fell'uig (Exclusive of Time for Resting) in Minutes 



Numerical 

 D. b. h. Y. P. & S. P. D. F. W. F. I. C. average 



28 15.00 19.00 13.80 12.80 15.15 



30 17.00 21.60 16.00 15.00 17.40 



32 19.50 24.00 18.80 17.10 19-85 



34 22.25 27.00 21.90 19.80 22.74 



36 25.00 30.00 25.00 22.60 25.65 



38 29.00 33.30 28.80 26.10 29.30 



40 3350 3700 32.70 30.00 33.30 



42 37.60 41.80 36.70 34.00 37.52 



44 43.00 46.00 40.80 38.50 42.07 



46 49.00 51.00 44.90 44.00 47.22 



48 5500 56.60 50.00 48.70 52.57 



50 60.50 63.00 54.60 54.60 58.17 



52 67.00 69.90 59.40 



54 74-00 77.00 64.25 



.Average time resting for all species, 12.28 minutes per tree. 



Without further knowledge, it is assumed that a diseased unmer- 

 chantable tree can be felled in the same time that an average merchant- 

 able tree of the same size and species can be felled, and the average 

 diameter as found in the stand is the same as the average merchantable 

 tree that is marked for felling. 



With a maximum of three trees per acre, therefore, with an average 

 diameter of 40 inches d. b. h. (which is very reasonable for the timber 

 marked in timber sales in California pine), the cost of felling diseased 

 trees is the cost of 33.30 minutes (work time) plus cost of 12.28 min- 

 utes (resting time) — a total of 45.58 minutes per tree, or a total of 

 136.74 minutes per acre. At $0.0104 per minute, this amounts to $1.42 

 per acre. The snag-disposal requirement provides that the tree be 

 opened up sufficiently to satisfy the forest officer as to its merchanta- 

 bility. In actual practice this is a very slight extra cost, probably less 

 than $0.01 per thousand feet of the timber cut, and very often the work 

 is applied to merchantable material that is obtained from the diseased 

 tree. 



