492 BULLETIN 1294, U. S. DEPARTMENT OF AGRICULTURE 
1. In the largest brush fields occur scattered patches or islands of 
virgin forest in naturally protected spots, where our knowledge of 
present fires shows that timber would be least susceptible to com- 
lete destruction. Also living stands of old-growth virgin timber are 
found immediately adjacent to brush fields and occupying similar 
sites. 
2. Scattered living trees and snags, bearing the evidence of many . 
fires, are not unusual in even the largest brush fields. Even in brush 
fields with no standing trees or snags a careful search nearly always 
reveals burnt remnants of tree trunks, stumps, or hollows formed by 
the complete burning out of stumps. 
3. Repeated burnings are shown in charred remains of brush found 
in brush fields. 
4, The woody species occurring as underbrush in the virgin forest 
are the same as those constituting the cover of adjacent brush fields, 
and brush is known to sprout after fires i which conifers have been 
destroyed. 
5. Reproduction of coniferous species becomes established in the 
brush fields wherever seed trees are present and fires are absent. 
The composition of the brush fields in various regions and on 
different sites and elevations varies even more than does the compo- 
sition of the forest, the climax type. In the same way the timber 
species that are so generally invading the brush fields vary. One 
common characteristic of brush fields, however, is that they are 
themselves due to fire, and that with the exclusion of fire they are 
being replaced with the climax type, the forest. 
Thus, although the gradual process of attrition or wearing down 
of the forest through repeated fires results in what may prove to be 
the final victory of the brush over timber species, forest reproduction 
still attempts to regain a foothold in the brush fields, an attempt to 
which fire has an important relation. (Pl. IX.) 
Estimates made after years of study of brush fields indicate that 
about two-thirds of their area is reproducing sufficiently to establish 
eventually a commercial forest. The extent to which tree reproduc- 
tion is taking place depends naturally on the number and distri- 
bution of seed trees available, for regeneration can be counted on to 
a distance of only a few hundred feet from seed trees. Smaller brush 
fields, generally speaking, are restocking in a satisfactory manner. 
It is chiefly in the very large brush areas of 5,000 acres or more, as 
11 In this connection, one fact of outstanding importance should be observed, namely, that conifers in 
the pine region, unlike the redwood, do not reproduce by sprouting, and that the various species of com- 
peting woody plants, ordinarily given the collective name of brush, do so prolifically. 
Hoffm an’s study of the Kinney Creek fire, Crater National Forest, gives the sprouting propensity of 
manzanita as follows: 
] | 
Main | | 
Bush | branches | B xick New | 
number Leh oe branches | shoots 
1 3 25 48 
2 2 10 32 
3 3 15 95 
_ On the Swartz Creek fire, Crater National Forest, Hoffman reports that manzanita established 91 seed- 
lings per square yard after the fire, and that the number of individuals increased 918 times in this instance, 
