NURSERY PRACTICE ON THE NATIONAL FORESTS. 43 
has the advantage of being easy to put on and remove, and it does 
not bring weed or grass seed to the beds. The last consideration is a 
very important one, since weed or grass seed brought in with a 
mulch is likely to impede nursery operations very seriously and add 
to their cost. A mulch should not be put on thickly enough to heat 
and should lie as loosely as possible. If winterkilling is probable, 
the tops should be covered; if only heaving threatens, just the soil 
around the roots need be covered. The mulch should be distributed 
after the ground is well frozen in the fall and removed in the spring 
before growth starts and as soon as there is little danger of serious 
freezing at night. It can be prevented from blowing away by cover- 
ing the seed beds with the protective frames. 
When snow comes early in the fall and lies until well into the 
spring it serves as a cover and usually makes artificial mulching 
unnecessary. In fact, where there is such a snow cover an artificial 
mulch in addition is very likely to cause heating and molding of the 
plants. Where the winters are cold and windy and the snowfall light 
mulching is generally considered advisable, but its absolute necessity 
can be determined only by trial. As the operation is expensive it 
should not be practiced unless essential. In Forest Service work it 
is practiced with all species only at the Monument, Converse Flats, 
and Gallinas Nurseries. To prevent winterkilling it is necessary 
to mulch 1-0 Arizona cypress at the Fort Bayard Nursery and 
white and Douglas firs and incense cedar at the Pilgrim Creek 
Nursery. At the Pocatello and Trapper Creek Nurseries mulch- 
ing is not practiced; but at the former some loss in Douglas 
fir is experienced from winterkilling, and at the latter a similar 
loss in western yellow pine has occurred where the snow blew 
off the beds in midwinter. At the Cottonwood Nursery mulch- 
ing is attended by a loss from heating and by molding due to the 
heavy snowfall, but some loss from spring heaving occurs there in 
thinly broadcasted beds of 1-0 Douglas fir, Engelmann spruce, and 
Norway spruce, and in drill-sown beds of the last two species. At 
the Wind River and Boulder Nurseries mulching has been found 
to be unnecessary, and at the former even harmful. At the Monu- 
ment Nursery a straw covering damages Austrian pine; and at the 
old Garden City Nursery it was found that heating and molding was 
much more likely to occur under straw than under a mulch of leaves. 
CARE OF SEEDLINGS IN SUCCEEDING YEARS. 
WATERING, WEEDING, AND SHADING. 
When plants are left in the seed beds longer than one year, the 
cultural operations are very similar to those of the first year. Water- 
ing and weeding are carried on as often as appear necessary. Shad- 
ing is unnecessary with most species, but not with all. Engelmann 
