Environmental Assessment

AFFECTED ENVIRONMENT & ENVIRONMENTAL CONSEQUENCES CHAPTER 3
management that enter and/or cross through harvest units would result in further reduction in the amount
of compacted soils. Table B-1 (Alternative 2) and Table B-2 (Alternative 3) in Appendix B display the
existing level and projected post-harvest level of detrimental soil impacts for each harvest unit under each
alternative. The majority of existing and new soil impacts would be confined to known locations in heavy
use areas, specifically roads, log landings and main skid trails. This facilitates where restoration
treatments would need to be implemented on compacted sites. The tables also display the number of
acres within each harvest unit that would be subsoiled upon completion of harvest activities and the level
of detrimental soil impacts that would remain upon completion of the subsoiling. The restoration
treatments are designed to promote maintenance or enhancement of soil quality, and are consistent with
LRMP interpretations of standards and guidelines SL-3 and SL-4 and Regional policy (FSM 2520, R-6
Supplement). Water sets, staging areas, and other management facilities located within the boundaries of
treatment units would not be subsoiled; these facilities would continue to be utilized to meet other
resource needs.
Monitoring of past subsoiling activities on the Deschutes National Forest has been shown to be effective
in restoring detrimentally compacted soils (Craigg, 2000, Deschutes Soil Monitoring, 1995). Dominant
soils in the planning area are well suited to tillage treatments due to naturally low bulk densities and the
absence of rock fragments within the soil profile. The winged subsoiling equipment used locally has been
shown to lift and shatter compacted soil layers in greater than 90 percent of the compacted zone with a
single equipment pass (Soils Report, pages 21 and 32). This results in the nearly complete loosening of
the compacted soil particles without causing substantial displacement. Subsoiled areas are expected to
reach full recovery within the short-term (five years) through natural recovery processes (Soils Report,
pages 21 and 32) under both alternatives.
Although the biological significance of subsoiling is less certain, these restoration treatments likely
improve subsurface habitat by restoring the soils ability to supply nutrients, moisture, and air that support
soil microorganisms. Research studies on the Deschutes National Forest have shown that the composition
of soil biota populations and distributions rebound back toward pre-impact conditions following
subsoiling treatments on compacted skid trails and log landings (Moldenke et al., 2000).
Post-harvest fuel reduction treatments would be limited by the use of whole tree yarding. This would
significantly reduce the need for post harvest mechanical fuel treatments (i.e. piling) and associated soil
impacts. Machinery would only be used to pile slash in random locations of two activity areas (EA Units
H19 and H28) proposed for regeneration harvest under Alternative 2. Only when previously existing
woodcutter slash and/or natural dead down material are present or the post sale whipping of submerchantable
material creates heavy fuel concentrations would mechanical piling be potentially necessary
in other activity areas. Machine piling on temporary roads or main skid trails would have no effect on the
overall extent of detrimentally disturbed soil because equipment would operate off the same logging
facilities used during yarding operations. This fuel reduction method would not cause additional soil
impacts because the piling and burning would occur on previously disturbed sites that already have
detrimental soil conditions.
Within lodgepole pine and mixed pine stands, utilization of dead and down material can greatly reduce
the need for mechanical piling. However, woodcutter slash and small down material has no salvage value
at this time. Piling and burning the piles to break up fuel continuity would be the preferred treatment to
meet fuel reduction objectives in those areas. Specialized, low-ground pressure machinery would be used
to accumulate woody materials for burning them on previously disturbed sites.
Both Alternatives 2 and 3 propose fuels reduction only treatments on 20,170 acres and 10,108 acres
respectively. These acres do not include commercial timber harvest. Some treatment acres include the
thinning of small trees four (4) inches dbh and smaller (pretreatment) prior to follow-up treatments such
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