ENVIRONMENTAL CONSEQUENCES in rocky mountain coniferous ...

The recovery rate of shrub volume from year two to four was also most favorable on
the understory-protected treatment; volumes increased from 35 percent of preharvest
volume at 2 years to 62 percent at 4 years (fig. 6). Shrub volume recovery rates were
roughly comparable on the other three treatments, ranging from 12 to 16 percent between
year two and four.
Twenty-three shrub species were found on the study area but six of these species
accounted for well over 90 percent of the total preharvest shrub volume. These six
were mountain map1 e (~cer gZabrwn) , ninebark (~h~socarpus malvaceus) , thimbleberry
(&bus pxrvif Zoms ) , rose (~osa gymnocarpa) , a1 der nu nus sinuata) , and servi ceberry
(~meZamhier a~nifoZia) . Their relative importance in terms of volume was a function
of treatment and number of years since harvest. The examples shown in figure 7 illustrate
the relative stability of some species and the responsiveness of others following
treatment. Ninebark, for example, retained the same relative amount of volume in both
treatments shown, whereas serviceberry changed 1 i ttle on the unders tory-protected
treatment and changed a lot on the intermediate-utilization-and-burned treatment;
mountain maple's re1 ati ve amount of vol ume changed substantially on both treatments
(fig. 7).
YEAR
YEAR
Figure 7.--Relative response, as measured by volume, of the major shrub species to
two residues management treatments: (A) Understory-protected treatment, (BI Inder-
mediate-utiZization-and-burned treatment.