PLANT SUCCESSION AND RANGE MANAGEMENT. 53 
though with less relish than sheep. Several of the more conspicuous 
plants, like tarweed, gilia, etc., are practically disregarded by stock. 
FORAGE PRODUCTION. 
The amount of forage produced on lands in the first or early weed 
stage is far less than that on lands supporting any of the higher stages 
of plant growth. • Like the second or late weed cover, the ruderal-weed 
cover is best suited for the grazing of sheep, but the carrying capacity 
is exceedingly low and the forage distinctly inferior. Aside from 
the fact that little of the herbage produced is grazed after about the 
first week in August, anything approaching complete utilization of 
the forage crop is apt to stimulate erosion of a most destructive char- 
acter. Hence range lands in the ruderal-weed stage must be man- 
aged in the most expert way ; anything approaching maximum utili- 
zation is hardly to be considered if the more permanent and desirable 
cover is ultimately to gain dominion over the soil. 
SUMMARY OF THE RUDERAL-EARLY-WEED CONSOCIATION. 
On lands where the soil has been so seriously impaired as no longer 
to afford a congenial habitat for the growth of perennial species, the 
cover consists essentially of annual plants. This first or early weed 
stage of which goosefoot or lamb's-quarters, slender-leaved collomia 
tarweed, Tolmie's orthocarpus, Douglas knot weed, and tansy mus- 
tard are typical examples, completes its growth in about 6 weeks 
after the sprouting of the seed. As the plants are entirely dependent 
upon seed for their perpetuation, their seed habits are exceptionally 
strong, the viability of the seed from year to year averaging con- 
siderably higher than that of the perennial plants. In spite of 
strong seed habits, however, there is a wider variation from year to 
year in the density of the stand of the early-weed stage than in any 
other type. This is chiefly due to the fact that there is not always 
ample moisture for plant life in the superficial soil layer in which the 
feeding roots of this consociation are located. While often variable 
in density, the ruderal-weed type nevertheless persists until enough 
organic matter has been accumulated in the soil to favor the estab- 
lishment of plants of the second-weed stage. 
Little forage is produced by the first- weed type. While a consid- 
erable number of species are grazed by sheep (few are eaten by cattle 
and practically none by horses), only a small amount of dry matter 
is produced. Douglas knotweed, the most abundant species, is 
cropped with moderate relish both by sheep and cattle and probably 
furnishes as much feed as all the other annuals combined. However, 
the ruderal-weed cover is grazed only when the herbage is succulent 
and tender. In view of the early maturity of the vegetation and the 
fact that the first-weed-stage cover affords poor protection of the 
