1(f)/ 



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^g^y United States 

 Department of 

 Agriculture 



Forest Service 



Northeastern Forest 

 Experiment Station 



Research Note 

 NE-329 



1985 



Relationships of Tree Age 

 to Diameter in Old-Growth 

 Northern Hardwoods 

 and Spruce-Fir 



William B. Leak 



Abstract 



Regressions are given for predicting age from diameter for 10 different 

 species of trees or shrubs in old-growth northern hardwood and spruce-fir 

 stands. 



Tree age is difficult to measure 

 in old-growth or virgin stands 

 because of the large size of the 

 trees and the abundance of hollow 

 or rotten boles. In two previous 

 studies of age distribution in old 

 growth hardwoods and spruce-fir 

 (Leak 1974, 1975), age was meas- 

 ured on suitable sample trees and 

 regressed over tree diameter for 

 each species; then these 

 regressions were used to estimate 

 the age of trees whose diameter 

 only had been measured. The 

 regressions used to estimate age 

 in these two studies are summa- 

 rized in this paper to make them 

 readily available to others studying 

 the characteristics of old-growth 

 forests in New England. 



Methods 



The old-growth hardwood stand 

 was a 40- to 50-acre tract of virgin 

 northern hardwoods in the Bowl 

 Research Natural Area on the 

 southern edge of the White 

 Mountain National Forest. Its eleva- 

 tion is between 1900 and 2100 feet. 

 The soil is a fine till (Leak 1982) on a 

 fairly steep slope. The spruce-fir 

 stand was a portion of a several- 

 hundred-acre tract of virgin spruce- 

 fir in the Nancy Brook Scenic Area 

 on the White Mountain National 

 Forest. The area sampled lies at 

 about 2900 feet elevation, and the 

 soil is primarily wet and dry 

 compact till (Leak 1982). 



In both areas, a series of plots 

 were taken to estimate diameter 



distribution, and a small subsample 

 was taken over a range of tree (and 

 shrub) sizes and species to estimate 

 age. Age was determined by 

 counting terminal bud scars (if 

 visible) on very small stems and 

 from increment cores on larger 

 stems. In selecting trees for 

 increment boring, stems with 

 advanced decay were avoided, 

 which may have eliminated certain 

 of the older or less vigorous (slower 

 growing) trees from the sample. 

 Both tree diameter and age were 

 determined at the top of the root 

 swell — the point where the bole 

 begins to swell into the stump or 

 root collar. The total number of 

 samples (all species) was 338 (Table 

 1). 



1 



