TABLE 2. — Average number of rings per inch at d.b.h. for red pine thinned to the indicated basal 
area every 10 years 
Site index 50 
Site index 60 
ieee Square feet of basal 
area per acre 
( years ) 
Square feet of basal 
area per acre 
90 120 
35 - 45 14 22 
45 - 55 12 20 
09 - 65 12 18 
65 - 75 11 20 
75 - 85 11 20 
85 - 95 12 20 
95 - 105 12 22 
105 - 115 12 22 
115 - 125 14 25 
125 - 135 14 25 
135 - 145 17 29 
145 - 155 17 33 
155 - 165 Gi) 33 
29 12 18 29 
29 10 17 25 
33 10 15 25 
33 8 15 25 
33 8 14 22 
33 8 14 25 
40 7 14 25 
40 8 14 29 
50 Gai) 14 29 
00 — 14 29 
50 —_— 15 29 
67 — 14 33 
67 — 14 29 
1 Stand clearcut at beginning of period because of low number of trees per acre. 
TABLE 3. — Number of red pine trees per acre after thinning to the indicated basal area every 10 years 
Site index 50 
Site index 60 
biel Square feet of basal Square feet of basal 
area per acre area per acre 
(years ) 
90 120 150 90 120 150 
35 800 1,200 1,600 800 1,200 1,600 
(before thinning ) 
35 434 794 1,226 405 744 1,156 
45 284 570 946 253 515 865 
55 194 422 749 165 368 665 
65 138 S23 610 112 271 525 
75 102 255 508 78 205 424 
85 79 207 433 57 160 350 
95 63 173 378 43 128 294 
105 51 147 335 33 104 252 
115 43 128 303 (1) 87 220 
125 38 114 277 — 74 194 
135 33 102 257 — 63 174 
145 30 93 241 — 55 156 
155 Gy) 86 2211, — 48 142 
1 Stand clearcut at this age because 
stands on site-index-50 land, growth rates are 
very low at older ages, with never fewer than 
40 annual rings per inch after age 95. 
The advantages of getting larger diam- 
eters at earlier ages from low-density man- 
agement must be weighed against the smaller 
of low number of trees per acre. 
number of trees available for harvest (table 
3). At any age there are fewer trees in low- 
density stands than in high. It is also true 
that in low-density stands fewer trees per acre 
are available for harvest when they reach a 
given size (compare table 3 and figure 1). 
