ENVIRONMENTAL CONSEQUENCES in rocky mountain coniferous ...

Control Chipped Picked up Broadcast Piled and Piled and
and and Burned Burned Burned
Spread Removed (in roml Ibetmn roml
LOGGING RESIDUE DISPOSAL TREATMENTS
Figure 5. --Density of vegetative cover associated with various residue treatments
on ZodgepoZe pine clearcuts .
ABOVE-GROUND BIOMASS
The effects of logging and residue treatments on the production of above-ground
biomass of grasses and forbs in 1977 are shown in figure 6. In the unlogged
control areas, the production of herbaceous biomass averaged about 310 pounds per
acre. On sites where residue was chipped and respread, herbaceous regrowth was
restricted to only about one-eighth of that on the control areas.
The greatest production, 980 pounds per acre, was measured on sites where
logging residue was picked up, removed for chipping, but not respread. Not only
were these areas opened to sun1 ight by clearcutting, but the existing understory
vegetation was not damaged by machinery or fire. These sites retained the most
potential for increasing the production of herbaceous biomass.
On sites that were broadcast burned, herbaceous biomass production averaged
800 pounds per acre. Apparently the quantities of residue left following logging
were not sufficiently concentrated to support the hot fires that greatly damage
herbaceous vegetation.
Average production of herbaceous biomass where logging residue was windrowed
and burned was about 400 pounds per acre, almost as low as in the relatively
unproductive control areas. This low production rate reflects the destruction of a
substantial portion of herbaceous plants by high fire intensities developed during
burning of the windrows.