Environmental Assessment

AFFECTED ENVIRONMENT & ENVIRONMENTAL CONSEQUENCES CHAPTER 3
A cool-temperature prescribed burn would remove some of the surface litter and duff materials without
exposing extensive areas of bare mineral soil. Effects to the soil resource include:
• a reduction of fuel loadings and wildfire potential;
• increased nutrient availability in localized areas; and
• maintenance of organic matter that supports biotic habitat for mycorrhizal fungi and
microorganism populations.
Assuming the same or similar burning prescriptions and conditions, Alternative 2, because it prescribes
the use of fire on more acres than Alternative 3, has a somewhat greater positive effect on soils than does
Alternative 3 in the short-term nutrient availability
Design criteria, mitigation measures, and best management practices (Soils Report pages 33-36) are
expected to minimize the amount of bare soil created as a result of timber harvest and fuel reduction
activities regardless of the alternative. Long-term, more than five (5) years, there is likely little or no
measurable difference in the amounts of CWM that would be available under either alternative.
Sensitive Soils
The LRMP identifies criteria for identifying soils that are sensitive to management needs (LRMP,
Appendix 14, Objective 5, page 14-2). For the planning area, these include:
soils on slopes greater than 30 percent;
soils associated with frost pockets in cold air drainages;
soils that occur in localized areas of rocky lava flows; and
soils with high or severe hazard rating for surface erosion.
There are no potentially wet soils with high water tables.
Approximately 46 percent (24,976 acres) of the planning area contains landtypes with localized areas of
sensitive soils. Although a relatively large part of the planning area contains landtypes with sensitive soil
concerns, only portions of these total landtype acres actually have sensitive soils meeting the above listed
criteria. Areas with sensitive soils are typically confined to specific segments of the dominant landform
and they are generally too small to delineate on maps.
Table 3-29 displays the Soil Resource Inventory (SRI) unit designation, the landform types, the type of
management concern associated with the landform type, and the number of acres within the planning area
associated with the landform type or types.
Table 3-29 Landform Types and Sensitive Soils
SRI Map Unit Symbol Geomorphology (Representative landforms)
3-106
Type of
Concern 49
Landtype
Acres
11, 7C, NA, NB Rough, uneven lava flows 3 9,649
7, 15 Depressions or Flats 2 3,542
4C Alluvial fans and toeslopes 4 1,266
14, LG Edges of lava flows with steep uneven slopes 1, 3 269
49, 91 Steep slopes of outwash plains, mountain slopes 1, 4 6,060
68, 80, 81, 82, 7H, 7K Steep slopes on volcanoes, buttes, ridges, and cinder cones. 1 4,190
49 Management Concerns: 1.) On slopes greater than 30 percent, loose sandy soils are susceptible to soil displacement; 2)
Very low productivity due to frost heaving, low fertility, and temperature extremes; 3) Sensitive soils with variable depths in
pockets and cracks of rocky, uneven lava flows; and 4) Sensitive soils with a high or severe hazard for surface erosion.