42 BULLETIN" 299_, U. S. DEPAKTMENT OF AGRICULTURE. 
old stand it may form but a very small proportion (PL XIV, fig. 1), 
perhaps only three or four seed trees per acre. 
The fact that white and green ash have male and female flowers 
borne on separate trees will not usually interfere with ash reproduc- 
tion cuttings, as such cuttings will be made after it is apparent that 
there is going to be a good seed year, and the tree which will have the 
most seed can be picked out and reserved. In preliminary reproduc- 
tion cuttings (to induce seed production) it should be remembered, 
however, that one large-crowned male tree per acre will pollinate 
more than enough flowers of female trees on that acre, and the remain- 
ing males can be removed if desired. Determination of sex can be 
made by marking trees which bear seed (female trees) in advance of 
such cuttings. In mixed stands with a small percentage of ash and 
where the sexes have not been determined, it will be best to leave all 
large-crowned ash trees. 
METHODS OF CUTTING. 
The methods of cutting to secure natural reproduction of ash may 
be grouped under two general systems ; the shelterwood system and 
the clean-cutting system, the former being adapted to all sites on 
which ash grows, the latter to a limited range of sites. The best 
method to use in any particular case depends on a number of factors: 
The species to be reproduced; the site, especially soil moisture and 
soil covering; age and density of the stand, including the amount 
and character of the undergrowth ; and proportion of ash in the mature 
stand. 
SHELTERWOOD SYSTEM. 
The shelterwood system consists in the more or less gradual removal 
of the mature stand, allowing reproduction to get well started under 
the shelter of the mature stand before removing it entirely. This 
system is especially suitable to upland white ash, as it preserves soil 
moisture, a.liberal amount of which is necessary for germination and 
seedling establishment. The method of cutting to be used varies 
with the density of the stand. 
In comparatively dense stands the mature trees should be removed 
in two or three cuttings: First, a seed cutting, often unnecessary, 
consisting in opening up around ash trees (and trees of other species 
it is wished to favor) to induce them to seed freely; second, a heavy 
thinning or partial clearance in the year of good seed production 
removing one-quarter to one-half of the volume of the stand; third, 
removal of the remaining stand a year later or as soon as practicable 
after reproduction has taken place. Where these cuttings are made 
with reference to a number of small areas — thinning out around 
