COTTONWOOD IN THE MISSISSIPPI VALLEY. 838 
so that their shade may not suppress any of the young growth. 
Most pure stands, however, are accessible to the river, which makes 
it practicable, as a rule, to return for any seed trees within a year or 
two of the first cut. With only a few logs to handle it will often be 
possible to wait till high water and then float them out to the river 
bank, thus obviating the much greater expense of hauling. In such 
cases there would probably be no extra expense connected with leavy- 
ing seed trees. If hauling were necessary, however, it might cost 
fully 50 per cent more to get out this scattered material. After the 
short interval of only a year or two, little if any additional swamping 
would be necessary to open up the former logging roads, but the 
haulers would lose considerable time in locating and loading the 
scattered logs and would probably get out no more than two-thirds 
as much per day as when working in heavier stands. If hauling 
under ordinary conditions costs $3 to $4 per thousand, it might in- 
crease in the latter instance to from $4.50 to $6 per thousand. The 
additional $1.50 to $2 per thousand feet would then represent the cost 
of leaving seed trees. If these are left as recommended, they should 
not average over 750 board feet per acre, which would make their 
cost at most run from $1.20 to $1.50 per acre. 
PREPARATION OF THE GROUND. 
Pure thickets of cottonwood, up to 20 or 25 years at least, are quite 
free from undergrowth, but at the age of 30 or 35 years a large 
variety of shrubs, vines, and weeds usually come up under the main 
stand. Such growth consists largely of peppervine, poison ivy, 
briers, privet, dogwood, and innumerable species of herbaceous char- 
acter. In the more open mature stands undergrowth and weeds 
often cover most of the ground. In addition, there are often numer- 
ous suppressed or overtopped trees of less valuable species, such 
as sycamore, hackberry, and elm. Such trees are usually small, but 
if left after lumbering would soon develop spreading crowns and 
shade much of the area. All such growth is detrimental to cotton- 
wood reproduction. To insure natural renewal of the stands, there- 
fore, it will not be sufficient merely to leave seed trees, but in addi- 
tion the ground must be cleared of all undergrowth. If the resulting 
slash is very abundant, it may be best to pile it with the cottonwood 
tops. In normally dense stands, however, this will seldom be neces- 
sary, since here the brush is not rank. Burning the slash will seldom 
be of benefit, except in the case of a rank growth of cane or weeds, 
which may be killed off by a carefully controlled surface fire. Sur- 
face fires do not run rapidly in most parts of the bottoms because 
of the small amount of inflammable material. Dry cottonwood 
leaves, moreover, are said to be much less inflammable than those 
