TIMBER GEO WIXG AKD LOGGING PEACTICE IN CALIFORNIA 25 
is used onl}^ on level land or on very gentle slopes. The wheels are 
operated on roads swamped out from the landing, with short spurs 
to the individual trees or loads of logs which are bunched with teams. 
If brush or advance reproduction is lacking, scanty, or low in height, 
little swamj^ing is necessary. 
Fig. 7.— the EFFECTS OF BIG-WHEEL LOGGING SEEN FROM THE AIR 
The biff-wheel roads, as viewed by airplane, join the spur in irregular lines 
that rarely sweep the ground as destructively as in machine logging. This view 
may be compared with airplane views of machine logging in Figures 9, 11, 
and 14. 
At present big- wheel yarding is used only in the east side yellow- 
pine type and, to some extent, in the yellow pine-white fir of the 
same region. This discussion refers in the main to the first-named 
type in which big- wheel logging is characteristic. 
The damage to seed trees is negligible, but there is considerable 
loss of seedlings, saplings, and small poles owing to swamping out 
roads. On a well-managed national forest cutting area reproduction 
74722°— 26 — -4 
