THE AMERICAN MIDLAND NATURALIST 
 
It has been demonstrated that burning of sagebrush in various areas as in

northern Colorado (Hanson, 1929) and in Utah (Stoddart, 1938) is followed

by such great increases in the stand of grass as to indicate that the climax

vegetation in these areas is grassland rather than sagebrush. Controlled
graz- 
ing and prevention of repeated fires are necessary, following burning, or
weedy 
grasses, as downy brome, and worthless shrubs, as little rabbitbrush and
match- 
weed will invade (Pickford, 1932). On severely overgrazed and burned sage-

brush areas, as well as on abandoned plowed lands, various weeds, as tansy

mustard, tumble mustard, and flixweed invade. These weeds serve as host 
plants during the spring to the beet leaf-hopper, the insect that transmits
the 
curly top virus disease which causes such large periodic losses to sugar-beets,

beans and tomatoes as to delimit the areas in which these crops can be success-

fully grown (Piemeisel and Chamberlin, 1936). Control of curly top disease

is dependent upon plant succession replacing the early weed stage, in which

mustards are prominent, by downy brome grass (requiring about 5 years in

favorable locations), followed by perennial grasses and shrubs, and by preven-

tion of overgrazing, excessive burning, unwise cultivation, and other practises

which initiate the weed invasion. 
As knowledge of plant succession and fire becomes more widely dissemi- 
nated man will increasingly use them as tools in land management. For 
example, in southern California where chaparral fires frequently expose the

soil to excessive runoff and erosion, succession has been speeded up by success-

fully sowing mustard by airplane (Weaver and Clements, 1938). Another 
example is furnished by Korstian (1937), who pointed out the need for 
encouraging succession by artificial planting on the burned and cut-over
spruce 
lands of the southern Appalachians if coniferous cover is to be restored
within 
a reasonable length of time. He stated that the best time for planting is

immediately after a fire, provided adequate fire protection can be assured
and 
where serious hardwood competition will not occur. Bews (1926) reports how

the conflicting opinions regarding the value of burning grasslands in South

Africa had developed and how they could be reconciled by analyses from the

successional viewpoint of numerous observations. In moderately dry areas

burning is iniurious because it throws back the succession from the climax

Themeda and Andropogon which are good grazing to an earlier stage domi- 
nated by relatively worthless species of Aristida, Eragrostis and others.
In 
moister areas where forest is the climax burning tends to destroy Tambookie

grasses and woody plants and causes the succession to revert to the earlier,

desired Themeda and Andropogon stage. 
Conclusion 
Fire has been used as a tool in the following land management practises:

1. Destruction of. debris as straw and other crop residues, logging slash,

etc., to reduce fire hazard and to facilitate cropping or plant succession.

2. Destruction of pests such as weeds, insects and diseases. 
3. Clearing land for cultivation or to improve conditions for desired plants