Table 9-9. Percentage of Forest Land in Each Sampling Unit by Stand 

 Size Classa. 



Stand size class Unit 



Capital Hancock Washington 



Sawtimber and pole 38 53 63 



Sapling-seedling and nonstocked 62 47 37 



^Ferguson and Kingsley 1972, 



The pattern of stand productivity at different ages was examined after 

 clearcutting a 55-year old hardwood stand in New Hampshire. Within 2 years 

 productivity was 387o of that before cutting, and by 6 years productivity 

 exceeded that of the mature forest (Bormann and Likens 1979). Following this, 

 a slight decrease in net productivity took place; the transition from one 

 stage of succession to another generally is not smooth. Young and 

 coworkers(1979) simulated stand productivity over time (15 to 55 years) for 

 softwood and hardwood stands on dry, meso, and wet sites. They found a steady 

 decline in productivity in all stands with the exception of hardwoods on dry 

 sites, which showed a steady increase. 



Stand productivity also varies with the level of soil moisture of the site. 

 For both hardwoods and softwoods, at all ages, stands on meso (moderately wet 

 or dry) sites are more productive than those on either dry or wet sites (Young 

 et al. 1979). Hardwoods on dry sites are initially less productive (15 years) 

 than those on wet sites but at 55 years they are more than twice as productive 

 and almost equal those on meso sites. Softwoods are also more productive 

 initially on wet sites but at 55 years they are only slightly more productive. 



The forest industry is concerned with productivity of merchantable wood, which 

 accounts for about 35% of the total productivity of a forest. The net annual 

 growth of merchantable timber volume (biomass) for the three forest units 

 sampled along the coast is summarized in table 9-10. Net production of 

 commercial products ranges from 0.4 tons/acre/year (0.9 t/ha/yr) in the 

 Hancock unit to 0.5 tons/acre/year (1.1 t/ha/yr) in the Capitol unit. The 

 greater productivity of the latter may be due to the higher percentage of 

 immature stands as described under "Biomass" above. 



9-18 



