Environmental Assessment

AFFECTED ENVIRONMENT & ENVIRONMENTAL CONSEQUENCES CHAPTER 3
and Sand Springs portions of the planning area, that had management activities implemented prior to
LRMP implementation in 1990, likely contain less than desired amounts of CWM. It is likely that levels
of both CWM and surface organic matter have been increasing as additional material has accumulated
over time through natural mortality, windfall, recruitment of fallen snags, and litter fall.
Alternative 1 - Short-term (up to five (5) years) levels of CWM and surface organic matter would
continue to be maintained or improve until a wildfire event. In forested areas, CWM would be expected
to continue to increase through natural mortality, windfall, and recruitment of fallen trees and snags. In
both forested and xeric shrub areas, short-term nutrient sources would also increase through the
accumulation of small woody materials from shrub and tree branches, annual leaf and needle fall, and the
decomposition of grass and forb materials. Existing and projected high fuel loadings would be expected
to support an uncharacteristic, high intensity wildfire that is capable of consuming all of the surface
organic matter and most if not all of the accumulated CWM in areas when it occurred. The timing and
location of such an event cannot be determined only that it would be expected to occur.
It is also important to note that on the eastside of the Deschutes National Forest (which includes the
Opine planning area), wildfires occurring during dry summer months typically consume even larger
diameter (12 inches and larger) downed logs (Soils Report page 9).
Long-term, greater than five (5) years, fuel loadings in xeric shrub communities, transitional range, and
forested areas would continue to increase thereby increasing the risk of an uncharacteristic, high intensity
wildfire. These conditions increase the risk that, should such a fire occur, large areas of vegetation,
coarse woody material, and surface organic matter would be killed or consumed and large areas of soil
exposed to subsequent wind and water erosion. High intensity fires and/or long duration burning,
especially in large fuels such as logs and snags, increases the potential for the development of
hydrophobic soils, the volatilization of soil nutrients, the reduction and/or loss of soil productivity, the
destruction of the litter layer, and increases the potential for accelerated wind erosion. These types of fire
remove or reduce coarse woody material that provides long-term nutrient input and water storage
capability that help to support the growth and development of both flora and fauna. In forested areas, at
least some of the CWM losses of logs and snags would, over the long-term would be at least partially
replaced by trees killed by fire and falling to the forest floor.
Although hazardous fuels have been reduced in some previously managed areas, fire exclusion has
resulted in undesirable vegetation conditions and excessive fuel loadings in other portions of the planning
area. This alternative would defer fuel reduction opportunities at this time. In forested areas, coarse
woody materials have accumulated through natural mortality, windfall, and recruitment of fallen snags
over time. If a large amount of fuel is present during a future wildfire, soil temperatures can remain high
for an extended period of time and excessive soil heating would be expected to produce detrimental
changes in soil chemical, physical, and biological properties. Severely burned soil would mainly be
confined to localized microsites beneath downed logs, stumps, or around the root crowns of individual
trees. Severe burning may cause soils to repel water, and the loss of protective ground cover increases the
potential for accelerated surface erosion by water and wind.
Within the grass/shrub communities, fires are usually fast moving and surface temperatures are not
elevated long enough to cause severely burned soils. Some short-term increases in surface erosion would
be expected until vegetation recovers but the time the soil is exposed is short because green-up of
herbaceous vegetation soon follows precipitation events. In those areas where tree encroachment has
occurred, there would be an increasing risk of localized occurrences of severely burned soils where large
fuels such as logs and stumps are present.
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