694 



TIMBER RESOURCES FOR AMERICA'S FUTUKE 



Seed-tree classification. — The seed-tree data in 

 table 106 refers to standard seed trees. For 

 seed trees above standard, corresponding rating 

 values of column 1 were multiplied by l)i; for 

 substandard seed trees, the ratings were multiplied 



A standard seed tree, as referred to in table 106, 

 was required to meet the general seed-tree defi- 

 nition and in addition to be 12 inches or larger in 

 d. b. h. if hemlock, cedar or spruce, or 18 inches 

 or larger in d. b. h. if of other species, including 

 Douglas-fir; it was also required to have a live 

 crown length equal to )i to Vz of total tree height. 

 Seed trees considered above standard met the 

 above specifications but, in addition, had a live 

 crown length more than Vz of total tree height. 



Substandard seed trees were recognized as trees 

 of seed-bearing size and age that did not meet 

 d. b. h. or crown requirements of standard seed 

 trees but did meet the general seed-tree definition 

 in other respects. 



Seedbed condition. — The basis for classifying 

 seedbed conditions for the Douglas-fir and other 

 type groups west of the Cascade summit in the 

 Pacific Northwest is summarized as follows: 



Rating value Seedbed condition on a i-milacre quadrat 



3 (Good) (a) 50 percent or more of surface favor- 

 able for seedling establishment 

 and growth, or 

 (b) 2 seedlings less than 2 years old and 

 free to grow. 



2 (Fair) (a) 20 to 50 percent of surface favorable 



for seedling establishment and 

 growth, or 

 (b) 1 seedling less than 2 years old and 

 free to grow. 



1 (Poor) (a) Less than 20 percent favorable for 



seedling establishment and growth, 

 or 

 (b) 1 or more seedlings less than 2 years 

 old in a questionable position for 

 normal development. 



(Very poor) Not likely to restock. A rating of zero 



resulted in classing the point as "no 

 stocking in prospect," regardless of 

 the value assigned in the rating of 

 other factors. 



The judgment and experience of local field 

 examiners in interpreting the classification of seed- 

 bed conditions was supplemented by the following 

 guides: 



Favorable seedbed. — Uncompacted mineral soil 

 is basic for ideal seedbed conditions. In addition 

 to receptive soil, the following surface conditions 

 are favorable: (1) A light, vegetative shade of 

 approximately 20 percent (below and above 20 

 percent density cover conditions become progres- 

 sively less favorable), and (2) dead shade from 

 logs, stumps, and light slash. 



Unfavorable. — Generally the following conditions 

 are indicative of a zero rating for seedbed condi- 

 tions: (1) Perennial grasses occupying 80 percent 



or better of the quadrat ; (2) herbaceous cover 

 using 80 percent or more of the area (includes 

 overhead shade as well as stem and root competi- 

 tion); (3) accumulation of debris, duft", rotten 

 wood, etc., which are known to be unfavorable 

 for the species rated; and (4) when noncount 

 species dominate the 4-milacre plot. 



Slope and exposure. — The basis for classifying 

 slope and exposure conditions for type groups west 

 of the Cascade summit in the Pacific Northwest 

 follows: 



Rating value 



■i (Good) 



Plot condition 

 e.xposure not 



— Slope and e.xposure not a factor in 

 seedling survival and development. 



2 (Fair) Survival of seedhngs questionable dur- 



ing periods of dry weather. 



1 (Poor) Conditions difficult for seedling sur- 



vival — such as dry, exposed south and 

 southwest slopes which approach 45 

 percent, and exposed hard compact 

 surfaces. 



Although slope and exposure were not considered 

 limiting factors for seed germination, they were 

 considered to have a pronounced effect on seedling 

 survival. South and southwest slopes that approx- 

 imate a gradient of 45 percent present the most 

 unfavorable conditions. On the other hand, north 

 and northeast slopes that approximate 45 percent 

 appear to be the most favorable. From this it 

 was assumed that level land — gentle slopes up to 

 20 percent for northwesterly and southeasterly 

 exposures — would approach the midway point, or 

 average conditions for seedling establishment and 

 survival. 



Douglas- Fir Type Group in California 



Prospective stocking was estimated by a system 

 similar to that used in the Pacific Northwest, i. e.. 

 by giving weighted ratings to seed source and 

 seedbed, and to slope and exposure. 



Seed-source standards. — The basis for rating 

 seed soiU"ce in California for the Douglas-fir type 

 group follows: 



Nu mber of 

 tree heights 

 from timber 

 Rating value edge .Supplemental allowance 



4 (Good) to 3 .\ value of I was allowed for eacti 



3 (Fair) 4 to 5 seed tree within one tree height 



2 (Poor) 6 to 7 of point. Exceptionallj' good 



over 7 seed trees were given a value 



of 2. Outside of blister rust 

 control areas, sugar pines were 

 not counted as seed trees. 



As in the Pacific Northwest, no combined rathig 

 of seed source was given a total value of more than 

 4, and any point with a "zero" rating for seed 

 source was classed as "no stocking in prospect." 



Seedbed — slope and exposure. — The data used for 

 rating these factors were the same as those used 

 for the Douglas-fir type group in the Pacific North- 

 west (see discussion immediately preceding). 



