REPRODUCTION OF WESTERN YELLOW PINE. 



87 



Application of standard. — The appli- 

 cation of the above standard to condi- 

 tions on the ground will be subject 

 to the following considerations : 



1. To give the purchaser at least 

 the amount in volume, from the sale 

 unit as a whole, which is guaranteed 

 by his contract. 



2. Where reproduction is not es- 

 tablished or is inadequately estab- 

 lished and blackjacks or intermediate 

 trees are not present to assure ade- 

 quate seeding and protection, sufficient 

 yellow pine trees will be left to meet 

 these silvicuitural requirements. The 

 number of such trees required for seed 

 and protection or shelter necessarily 

 varies, depending upon their condition. 

 For average conditions, where repro- 

 duction is not established, at least 

 three (3) windfirm good-crowned trees 

 less than 25 inches d. b. h. should be 

 left per acre, if available; if the only 

 suitable trees to leave are all over 2a 

 inches d. b. h., the number may be re- 

 duced to two (2) per acre. If, how- 

 ever, the condition of the trees or the 

 condition of the area with respect to 

 exposure, dryness, etc., is such that, in 

 the judgment of the marker, adequate 

 protection or seeding will not be af- 

 forded, a greater number should be 

 left. 



3. Where sufficient blackjacks and 

 intermediate trees for seed and shelter 

 are present, all yellow pine may be cut. 



4. In stands containing a mixture of 

 yellow pine, blackjacks of merchant- 

 able size, and poles, all yellow pines 

 may be cut except where needed in 

 openings for seed or protection, and 

 blackjacks and intermediate trees may 

 be marked for cutting, if their re- 

 moval is justified from a thinning 

 standpoint, or if badly defective or 

 diseased, provided they are not needed 

 for seed or protection. 



young trees. They not only shade out 

 seedlings within a considerable area 

 around their bases, but will retard 

 the growth of young trees within the 

 entire area occupied by their roo s, 

 which may extend over a radius >f 

 100 feet. 



Examinations prior to making a 

 sale should determine the amount of 

 timber which may be removed without 

 danger to reproduction. 



The blackjacks alone are rarely ade- 

 quate for seed production, because the 

 great majority of the trees in this class 

 are too small to bear much seed, or 

 occur in large groups where their 

 crowns are poorly developed, and their 

 seed is not effectively disseminated. 

 It has been shown under "Seed Supply" 

 and "Cutting" in this report that trees 

 below 21 inches in diameter, almost 

 exclusively blackjack, are ordinarily a 

 small factor in seed production. The 

 average yield of blackjacks over 11 

 inches diameter breast high in a good 

 seed year has been placed at one-half 

 pound per tree, but for blackjack over 

 20 inches the figure would be in the 

 neighborhood of 11 pounds. Yellow 

 pine of the type usually left after 

 cutting will produce about 2* pounds 

 per tree. Exceptionally good seed 

 trees may produce over 10 pounds. In 

 the attempt to fix a general guide ap- 

 plicable to large areas where detailed 

 classification of the trees is imprac- 

 tical, the elimination of trees below 21 

 inches is recommended. On this basis, 

 the minimum number of seed trees has 

 been placed at four per acre. The 

 instructions specify that where it is 

 necessary to supplement the blackjacks 

 with yellow pines, the number per acre 

 should be not less than three wind- 

 firm good-crowned trees, if under 25 

 inches, or two if all are over 25 inches. 

 The wording implies that trees over 

 25 inches in diameter should not be 

 left if smaller ones are available. This 

 provision is made because the larger 

 trees are less desirable as forest cap- 



