172 INTERMEDIATE CUTTINGS — THINNINGS 



Light demanding species with thin foliage may form nearly a 

 complete canopy with their crowns and still allow so much 

 light to reach the ground that the soil may deteriorate or an 

 undesirable growth of grass, weeds or underbrush start. An 

 understory is needed to protect the site whenever accretion 

 cuttings are made in a stand of thin foliaged trees. Such an 

 understory may be established by natural or artificial means. 



Accretion cuttings should be used only in the latter half of 

 relatively short rotations on soils where there are abundant 

 moisture and food materials available for increased growth 

 and where an understory can be developed naturally or 

 artificially for a small expenditure. 



A distinction should be made between accretion cuttings * 

 used as intermediate cuttings and hence keeping the cover 

 close enough to utiKze completely the productive power of the 

 site, and cuttings of a similar nature which permanently break 

 the cover and are essentially reproduction cuttings started 

 early in order to secure increased growth on selected trees. 



Nisbit' states that any thinning which removes over 15 

 per cent of the total basal area is an accretion cutting. 



The French Method.^ — (" Eclaircie par le haut " or " thin- 

 nings from above.") 



Under the French method, so called, every opportunity for 

 rapid growth is given to certain of the best dominant trees 

 by completely freeing them from competition comparatively 

 early in the rotation. As compared with the ordinary method 

 a thinning similar to Grade D or heavier is made in the inter- 

 mediate, co-dominant and dominant crown classes, while the 

 overtopped trees are allowed to remain except for a Grade A 

 thinning which removes the suppressed trees. (See Figs. 69 

 and 70.) 



In starting the French method a number of trees, sufficient 

 to stock the area at maturity and distributed as luiifonnly as 



