﻿WHITE PINE UNDER FOBEST MANAGEMENT. 15 



may not mark a heavy seed production over the entire range of white 

 pine, and a "seed year" may occur in some localities simultaneously 

 with an "off year " in others. Local conditions of soil and climate have 

 great influence on the frequency of seed years. Scarcity of water 

 stimulates seed production in most plants, and it is quite possihlo 

 that fluctuations in soil moisture may have some influence on the 

 frequency of seed years of white pine. * In off years not only is less 

 seed produced, but the ravages made upon the supply by birds and 

 rodents is more keenly felt. Insect damage, too, is concentrated, so 

 that a small crop is likely to be one of low quality as well. Even in 

 off years, however, seed production in some localities may be fairly 

 plentiful. 



The relatively long intervals between seed years put white pine at 

 a disadvantage, compared with trees which bear heavy crops more 

 frequently. Several of the broadleaf species bear seed abundantly 

 each year, and when these are shade-enduring trees with heavy 

 crowns they are often able, in company with underbrush, completely 

 to cover a cleared area, and so prevent white pine from obtaining a 

 foothold. In the Lake States, jack pine, which nearly every year 

 bears abundant crops of small, winged, fertile seed, is able to monopo- 

 lize cleared areas, practically to the exclusion of white pine. 



Seed Distribution. 



The chief agent of distribution of white pine seed is wind. Trees 

 standing on high, windy slopes and ridges may shed their seeds to a 

 distance of half a mile, or even more, over the adjoining lowland. In 

 valleys the range of seeding is very much less. On level land the 

 distance to which seeds will be carried in any number, when unob- 

 structed by crowns of other trees, is usually between 100 and 200 

 feet. Reproduction, of course, is densest and most even-aged near 

 the mother trees. Where abandoned fields or pastures adjoin white 

 pine woodland, dense even-aged stands of pine are almost sure to 

 develop, the stand becoming more open as its distance from the seed 

 supply increases. When seed trees are left well distributed on a cut- 

 over area, a fully stocked, even-aged second growth may often be 

 established after one or two full seed years (PI. TV, fig. 2) . When seed 

 trees are scarce or poorly distributed, complete restocking may require 

 a much longer time, or the result may be that other species, possibly 

 undesirable ones, will come in with the pine. From 5 to 10 good seed 

 trees per acre are usually sufficient to give a close, even-aged stand of 

 second growth. The number should never be less than 3 or 4, selected 

 with reference to the direction of the prevailing wind. 



1 Height and Dominance of the Douglas Fir, by T. C. Fry. Forestry Quarterly, vol., S ?/ No. 4, p. 467, 



