Soil Resource Report

Transcription

1 Soil Resource Report Swift Timber Sale Environmental Analysis Prepared by: Aldo Aguilar Soil Scientist for: Mount St. Helens Ranger District Gifford Pinchot National Forest 12/12/2014

2 Introduction This report summarized the effects on the soil resource of the proposed activities for the Swift Timber Sale. The extent of detrimental soil conditions within the units of the action alternative was analyzed. Quantitative analysis and professional judgment were used to evaluate soil quality. Soil Productivity The potential effects of the proposed activities on soil productivity are compaction, puddling, displacement, erosion, and severe burning. Losses in soil productivity due to these effects are limited to permanent features of the transportation system where soil quality remains degraded. Soil compaction inhibits root elongation, reduces the infiltration and storage of water and decreases the gaseous exchange between roots and the atmosphere. This can inhibit seedling establishment and reduce tree growth throughout the rotation. Reductions in soil productivity are proportional to the degree and extent of compacted soil. Puddling is the total loss of soil structure and usually occurs when equipment is operated on saturated soils. Puddling affects soil productivity in much the same way as compaction. The restrictions imposed upon forest management activities to limit soil compaction will usually also limit puddling. Puddling can result in rutting of skid trails which can reduce their usefulness for future entries. Equipment operations will be suspended when rutting exceeds 6 inches in depth. This will also allow for rehabilitation to be effective. Displacement of topsoil can remove soil nutrients from the root zone of desired vegetation and expose the soil to the forces of erosion. Most soil displacement results from equipment operations and will be limited as described above. In cable-harvested units, logs will be partially suspended or fully suspended to prevent gouging of soils sensitive to displacement or erosion. Soil erosion can result in nutrient-rich topsoil moving downslope, away from the root zone of desired vegetation. If eroded soil reaches a stream, it can reduce water quality. Exposed mineral soil may promote the invasion of a site by undesirable vegetation. Ground cover includes vegetation, litter, duff, rock larger than 3/4", slash, wood chips, and other organic residue. It also includes the crowns of shrubs and trees that are in contact with the ground up to one meter above the soil surface. Severe burning can result in nutrient loss through volatilization and from accelerated leaching. Waterrepellency can also be induced which may lead to increased erosion. Effects to Soil Organisms Compaction, puddling, displacement, erosion and severe burning of soils have the potential to affect individuals and populations of soil organisms including mycorrhizal fungi, soil-dwelling arthropods, nematodes and bacteria. Loss of organisms occurs through direct destruction from equipment operations and from loss of habitat or substrate. These losses are usually localized to the area of forest floor and/or topsoil disturbance, e.g. a skid trail. Soil Productivity Issue Indicators The degree or intensity of soil productivity losses is quite variable depending on the nature of the impacting mechanism. Compacted soil in heavily used skid trails and landings can result in decreased height and volume growth to adjacent trees and can persist for decades. Displacement of topsoil or Swift Timber Sale Page 2

3 nutrient loss from burning usually results in small, short-lived productivity losses. Losses in soil productivity associated with permanent features of the transportation system, including permanent roads and temporary roads, landings and skid trails needed for future entries, are essentially permanent. Restoration by subsoiling, fertilization and revegetation will initiate recovery of productivity. The effects of losses in soil productivity are direct in that they occur on site and affect only the area where they occur. Off-site effects can be readily avoided by constraints and mitigation measures that are routinely applied to these types of projects. Accumulated effects to soil productivity could become an issue where stands are entered repeatedly. On the Gifford Pinchot National Forest, stands of this nature are not widespread since most timber harvest has been stand regeneration. As commercial thinning becomes more widespread, careful harvest unit design will result in a transportation system, including skid trails that will facilitate future entries and remain within the 20 percent limit. Constraints and mitigation measures such as requiring the use of existing roads and skid trails and rehabilitation of any excesses by subsoiling will keep the impacts below the limit. On a watershed basis, soil effects are usually limited to much less than 20 percent of a watershed area as only a small portion of any one watershed is designated for stand management. Some of a watershed is non-forest (meadows, rock water, etc.) while other areas have stricter management standard and guidelines limiting stand management activities (riparian reserves, special wildlife habitats, or visual corridors). The activity areas themselves may not reach 15 percent (5 percent for roads) because some timber harvest operations such as skyline (cable) or helicopter logging cause minimal soil damage, usually less than 5 percent of an activity area. Careful operation of ground-based harvesting equipment can result in 10 percent or less impact to the unit. Measures such as subsoiling, revegetation and fertilization are intended to restore productivity and reduce extent of detrimental impacts. Soil Stability Environmental damage and societal effects are issues affected by mass wasting (Brown, 1985). Trees and other vegetation growth on landslide tracks is less than on adjacent soils. Landslides may increase turbidity and sedimentation. Large landslides scour channel banks and damage streamside vegetation and fish habitat. Landslides damage roads and bridges and can threaten life and property, affecting economics, political and legal status of responsible parties. Mass movements characteristically occur under high soil moisture conditions and usually develop or are accelerated during periods of abnormally high rainfall. Further, they are encouraged or accelerated by management actions such as logging operations that destruct the natural mechanical support on the slopes. Identification and avoidance of highly unstable areas and development and implementation of timber harvesting techniques least damaging to natural slope stability are the limited measures for prevention and control (Swanston, 1974). Unstable and potentially unstable slopes are designated as riparian reserves by the Northwest Forest Plan (NWFP). Gifford Pinchot National Forest earth sciences staff delineated preliminary riparian reserves with the understanding that these interim delineations would be field-verified on a project-by-project basis and reserve boundaries would be updated to reflect new information. Additional areas of unstable slopes discovered in field investigation are added to riparian reserves. Changes in soil and geology map data are incorporated in the Forest GIS layers from which updated riparian reserve maps can be generated. Swift Timber Sale Page 3

4 Affected Environment Geomorphology and Soil Types Landtype Association mapping (USDAFS GPNF 1999b, gplta) classifies landforms occupied by units of the Swift Timber Sale in four major landforms: Gently Sloping Glacial Lahar Plains (Gl-D/Q-V); formed by glacial scour of Quaternary lava flows, mantled with soils developed from volcanic tephra Gently Sloping Upland Benches, Plateaus (Q-V); formed by Quaternary lava flows, mantled with soils developed from volcanic tephra Steep, Moderately Dissected Mountain Slopes (T-Vm); formed by tectonic uplift and stream dissection, mantled with soils developed from colluvium from marine volcanic rocks and volcanic tephra Steep, Slightly Dissected Mountain Slopes (T-V); formed by tectonic uplift and stream dissection, mantled with soils developed from colluvium from marine volcanic rock Soil depth and soil textures are related to bedrock type, and influenced by topography. Lava flows from Indian Heaven area and its glacial deposits, along with glacial deposits from Mt. Adams, contribute to gentle topography and relatively shallower soils because the relatively young bedrock is less weathered and stronger. Steeper slopes around Lewis River tributaries have deeper soils formed from residual or colluvial weathered bedrock materials of volcanic origin, along with a greater potential for mass failures. A strong influence on soil formation in the project area has been volcanic ash and pumice from Mount St. Helens, Mount Adams, and other sources, although glacial till is a dominant parent material on gentler slopes. The area was mapped as part of the Soil Resource Inventory (Wade, et. al., 1992 and USDA FS, 1971). Soils in the units are suitable for timber harvest, in alignment with timberland suitability classification (FSM ), except in wetlands and wet meadows (Soil Mapping Unit 3). Current soils information for sensitive soils in the project area was collected on a site-specific basis. Soil Mapping Unit (SMU) locations were modified for accuracy at the project scale (Appendix A Soil Mapping) to reflect 2013 field observations and GIS analysis. The 87 units of the Swift Timber Sale contain 33 SMUs, some with 4 digit combinations called complexes (Appendix A Soil Mapping) across approximately 4600 acres of activity areas (harvest units). Gravelly loams on broad upland plateaus of SMU 17 occupy the most area within the units, but loamy soils on gentle benches and toeslopes of SMU 88 appear in 27 stands (Table 1). Of the soils rated as permitting ground based logging systems, seven SMUs within the activity areas rate high" potential for soil compaction, comprising 1000 acres, or about 22% of the activity areas. Except for 590 acres in SMU 29, ground based SMU ratings are either Low or Moderate for soil displacement. SMU s with a yes in Potentially Unstable column denote a component involving potentially unstable soils mapping. Refer to Slope Stability discussion below for conditions and project design features in those units. Surface erosion potential rating applies to topsoil when a disturbance removes all vegetative cover, including litter. Swift Timber Sale Page 4

5 Table 1. Selected Soil Mapping Interpretations (Wade, et. al., 1992) in Swift Timber Sale Swift Soil Map Unit (SMU) Units (Activity Areas) Acres Surface Erosion Compaction Potential Displacement Potential Fertility Potentially Unstable , Slight Moderate Moderate Low No , , , , , , , , , , , , , , 29.0 Moderate Low No , , , , 32.4 Slight Moderate Moderate Moderate No , , , 13.0 Moderate Moderate No , , , , , , , , , , , , , , Slight High Moderate Low- Moderate Moderate High Moderate Low- Moderate No No Swift Timber Sale Page 5

6 Table 1. Selected Soil Mapping Interpretations (Wade, et. al., 1992) in Swift Timber Sale Swift Soil Map Unit (SMU) Units (Activity Areas) Acres Surface Erosion Compaction Potential Displacement Potential Fertility , , , , , , , , , , , , , , , Moderate Moderate High Low- Moderate 58.6 Moderate Low No Moderate Moderate Moderate Low- Moderate Moderate Moderate- Moderate Moderate Yes High , , , , , , , , , , , , , , , , Moderate Low No , , , , , Moderate Low No 12.7 Moderate Moderate No Potentially Unstable No No Swift Timber Sale Page 6

7 Table 1. Selected Soil Mapping Interpretations (Wade, et. al., 1992) in Swift Timber Sale Swift Soil Map Unit (SMU) Units (Activity Areas) Acres Surface Erosion Compaction Potential Displacement Potential Fertility Potentially Unstable , Moderate Low No , , , , , , , , , , , , , , 7.5 Moderate Moderate Moderate Moderate No , , , Moderate Moderate Yes Swift Timber Sale Page 7

8 Table 1. Selected Soil Mapping Interpretations (Wade, et. al., 1992) in Swift Timber Sale Swift Soil Map Unit (SMU) Units (Activity Areas) Acres Surface Erosion Compaction Potential Displacement Potential Fertility , , , , , , , , , , , , , , , , , , , , , , , , , , Moderate Moderate- High Potentially Unstable Moderate Moderate No Moderate Low No , , , , , , , , , , , , , , Moderate Low No Swift Timber Sale Page 8

9 Table 1. Selected Soil Mapping Interpretations (Wade, et. al., 1992) in Swift Timber Sale Swift Soil Map Unit (SMU) Units (Activity Areas) Acres Surface Erosion Compaction Potential Displacement Potential Fertility Potentially Unstable , Moderate High Moderate Low No , , , , , , , Moderate High Moderate Low No , , , , , , , , , , 46.3 Moderate High Moderate Low No , 33.6 Moderate Low No , , , , , Slight High Moderate Low- Moderate 9.3 Moderate Yes Moderate Moderate- High Moderate Yes Moderate Low No , , Moderate Low Moderate Yes Moderate Moderate No Moderate Moderate Yes , Moderate Low No No Swift Timber Sale Page 9

10 Table 1. Selected Soil Mapping Interpretations (Wade, et. al., 1992) in Swift Timber Sale Swift Units (Activity Surface Compaction Displacement Areas) Acres Erosion Potential Potential Fertility Soil Map Unit (SMU) 3 (wet meadows) , , , , Potentially Unstable 0.4 Slight High Low Moderate No Implementation of the following Mitigation Measures would prevent excessive soil displacement and erosion. Ground-based equipment is not recommended in SMU s 59 and 5923 due to a high potential for subsurface soil erosion. Implementation of the following Mitigation Measures would provide sufficient ground cover for soils in the Swift Thin project (numbers correspond to Project Design Criteria and Mitigation Measures list on page 30): 1. Ground-based machinery will not be operated where soil water content is high enough to cause detrimental puddling 2. Mechanical harvesters, when traveling away from approved skid trails or roads will operate on a slash mat of limbs and tops 3. Areas of gouging or soil displacement resulting from logging systems will be treated to prevent rill and gully erosion and potential sediment delivery to stream courses 4. Forest Service will approve landings, skid trails and skyline corridors prior to timber felling 6. Landings will be located where past landings were located, unless a new location would cause less resource effect or where no past landings were used to harvest the unit 7. Temporary roads and landings will be closed and restored after harvest and related activities are complete 8. Periodic monitoring of ground-based activity on steep slopes Pre- bunching will be approved on a unit-by-unit basis on slopes greater than 35 %... Applicable Regulations and Guidance The Sustained Yield Forest Management Act of 1944 establishes sustained-yield units, in part, to secure the benefits of forests in maintenance of water supply, regulation of stream flow, prevention of soil erosion (Sec.1). The Clean Water Act of 1948 requires programs for the control of nonpoint sources of pollution be developed and implemented (Sec.101, a, 7). The Watershed Protection and Flood Prevention Act of 1954, (being mainly about flood control structures) also speaks to preserving, protecting, and improving the Nation's land and water resources and the quality of the environment. (Sec.1). The Multiple-Use Sustained Yield Act of 1960 states Sustained yield of the several products and services means the achievement and maintenance in perpetuity of a high-level annual or regular periodic outputs of the various renewable resources of the national forests without impairment of the productivity of the land. (16 U.S.C 531) (Sec. 4, b.). Swift Timber Sale Page 10

11 The National Environmental Policy Act of 1969 requires Federal actions attain the widest range of beneficial uses of the environment without degradation (Sec.101,b,3); to disclose the environmental impact of the proposed action; any adverse environmental effects which cannot be avoided should the proposal be implemented; the relationship between local short-term uses of man's environment and the maintenance and enhancement of long-term productivity; and any irreversible and irretrievable commitments of resources (Sec 102, C, i, ii, iv, v). The Forest and Rangeland Renewable Resources Planning Act of 1974 requires that we ensure that timber will be harvested from National Forest System lands only where-- (i) soil, slope, or other watershed conditions will not be irreversibly damaged; such cuts are carried out in a manner consistent with the protection of soil, watershed (Sec 6, g, 2, E, (i, v). The Federal Land Policy and Management Act of 1976 requires coordinated management of the various resources without permanent impairment of the productivity of the land and the quality of the environment (Sec 103, c). The Soil and Water Resources Conservation Act of 1977 requires a continuing appraisal of the soil, water, and related resources (including, but not limited to) data on the quality and quantity of soil data on the capability and limitations of those resources data on the changes that have occurred in the status and condition of those resources (Sec 5, a 1, 2, 3). The Northwest Forest Plan (USDA, USDI 1994) requires minimizing soil and litter disturbance that may occur as a result of yarding and operation of heavy equipment as a Standard and Guideline for Matrix (p. C-44). It also requires designating unstable and potentially unstable lands as riparian reserves (p. 9). Northwest Forest Plan Standards and Guidelines require ACS objectives be met, including Maintain and restore the sediment regime under which aquatic ecosystems evolved. Elements of the sediment regime include the timing, volume, rate, and character of sediment input, storage, and transport (p. B-11). The 1990 Gifford Pinchot National Forest Land and Resource Management Plan requires losses in soil productivity be limited to 20 percent or less of the unit. In the standard, unit or activity area is the total area for which ground-disturbing activity is planned and includes the transportation system, in and directly adjacent to, the unit. Soil Management Guidelines, as amended, will apply unless on-theground assessment indicates a change in the guidelines is necessary. The Forest Service Manual, Chapter 2520, R-6 Supplement No gives regional direction and clarification of terms. Soil Disturbance Calculations and Assumptions The extent of National Forest System roads was estimated using GIS analysis and included roads within and adjacent to each unit based on a 20 meter buffer around stand polygons. A conceptual map of temporary roads and landings approximated historical logging compaction using GIS, based on a 10 meter buffer around stand polygons. In addition to NFS roads, unauthorized roads and landings, a standard ghost 7% of stands that could have been logged on gentle slopes (based on SRI slope mapping) was assumed as impacted by skid trails. For the purpose of calculating acres of roads, National Forest System roads were assumed to be 6 meters wide, depending on field observations. Temporary roads were assumed to be 4 meters wide. Ground based logging landings were assumed to be one-quarter acre in area, helicopter landings one acre, and skyline logging landings were one eighth of an acre. GIS data is available in the project file. Swift Timber Sale Page 11

12 Areas with soil mapping of riparian reserves that were deemed stable by the Swift Timber Sale field investigations have no special management consideration but are still mapped as potentially unstable soils (Appendix A Soil Mapping). SMU polygons clipped by GIS within units that were less than 0.1 acres total in a unit (because of the GIS operation) were merged with an appropriate SMU adjacent to it within the unit boundaries. Generally, overlapping landings and roads between two units were double counted. Ground Based Logging Equipment on Steeper Slopes Use of ground-based equipment is proposed for certain logging operations on steeper slopes that are rated in the Soil Resource Inventory (Wade, 1992) as not permitting tractor logging. The Proposed Action includes allowing the use of mechanical cutting and harvesting machines to fell, limb, and bunch logs on slopes up to 45% within the Swift Timber Sale units. This practice is considered consistent with GP Forest Plan (Aguilar, 2014). A component of ground-based logging operations (use of mechanical cutting and harvesting machines) would be considered on a case-by-case basis on slopes up to 45 percent rather than being limited to 35 percent. The equipment would travel downhill through the units, not bearing the weight of logs as they travel, and return uphill on go-back roads designated by the Forest Service, as described in the Swift Timber Sale Soils and Aquatics Mitigation Measures and Design Features. Mechanical cutting and harvesting during ground-based logging is a relatively low impact step in logging operations. Mechanized felling, limb removal and bunching does not cause soil disturbance associated with movement of the logs, as compared to skidding, or physically removing trees from a stand by dragging or carrying logs (skidding). Professional opinion is that use of mechanical cutting and harvesting machines would not result in an increase in intensity of losses to soil quality because disturbance by equipment would be minimized. Mitigation Measures and Design Features specify one pass occurring on approved locations that have minimal dynamic and static load for the operations involved. Losses to above ground vegetation growth would likely be short term based on the more prevalent Forest wide experience with similar activity on gentler slopes. Mitigation measures and design features would prevent erosion and mass wasting, and would minimize compaction and displacement. Mechanical cutting and harvesting machines may reduce the effect of skidding trees by positioning them more accurately for retrieval by helicopter or cable system equipment. Professional judgment in support of mechanical cutting and harvesting was gained through field reviews, literature reviews, and discussions with Forest Service employees who are experienced with logging equipment and resulting ground conditions. Examples include: 1.) Acceptable or good results on volcanic soils of the East Fork Lewis River and Wind River watersheds were observed during field reviews of feller-buncher use. Field reviews of fellerbuncher use by Forest Service Soil Scientists on two separate visits showed acceptable or good results on local volcanic soils. 2.) Review of literature such as SDTDC Publication # , Steep Slope Logging Slash Treatment, gave insight into the abilities of available logging equipment, including the slope limit given in the Forest Plan amendment. 3.) communication with soil scientists across the Region made use of their collective knowledge and experience with effects of mechanized equipment on soils. Swift Timber Sale Page 12

13 Existing Condition of Soils Resources Soil Productivity/Soil Quality Evidence of ground based logging and other forest products harvest and recreational use exist within the Swift Timber Sale Unit boundaries. Non-system roads and landings that are remaining from past timber harvest (Table 2) and which have not been rehabilitated generally still have low to moderate compaction on older, overgrown roads or landings, or moderate to severe soil compaction on heavily used or heavily rocked non system roads and landings. Moderate to severe soil compaction has also been observed onsystem roads that currently have unapproved use. This analysis assumes that areas with extensive detrimental soil conditions have experienced losses in soil productivity in the long term (greater than fifty years). The analysis estimated detrimental conditions were within the 20% Forest Plan Standard for detrimental soil conditions (USDA 1990) in proposed activity areas. Timber Harvest Non-System Roads and Landings Stands in the activity areas were affected by timber sales recorded in Table 2, beginning with Skook Timber Sale in 1983 and most recently Limbo Timber Sale in Managed stands were generally clear-cut harvest, followed by planting. Management practices at that time did not restrict machine movement, skid trail density, removal of woody debris or intense burning; therefore detrimental effects to soil were sometimes higher than what Forest Plan standards and guidelines currently recommend. These past detrimental conditions continue to exist on the ground in various stages of natural recovery. Table 2. Timber sales affecting units of Swift Timber Sale Limbo Timber Sale 1997 Hardtime Timber Sale 1996 Point and Rush Timber Sales 1991 Drought Timber Sale 1990 Cas Salvage Timber Sale 1989a Brothers Timber Sale 1989 Term Timber Sale 1989 Quartzite Timber Sale 1988 Gabby Timber Sale 1988 Scallop, Oyster, and Kelp Timber Sales 1987 Kamloops, Willie, and Saska Timber Sales 1987 Skook Timber Sale Addendum 1987 Miller Creek Timber Sale 1986 Edge Buy-Back Timber Sale 1986a Atomic Dog Salvage Timber Sale 1986 Partridge II Timber Sale 1986 Redhead Timber Sale 1986 Bojo Salvage Timber Sale 1985 Foehn Salvage Timber Sale 1985 Ivory Salvage Timber Sale 1985 Swift Timber Sale Page 13

14 Table 2. Timber sales affecting units of Swift Timber Sale Beth SSTS Sales 1984 Gone Timber Sale 1984 Joint Timber Sale 1984 Solitaire Timber Sale 1984 Skook Timber Sale 1983 System Roads The analysis considered system roads to have soils in a non-productive condition in the long term (greater than fifty years). Most of the precipitation that falls on a compacted surface becomes surface runoff. The area of system roads was estimated using GIS analysis and includes roads within and adjacent to each unit boundary. Data for the analysis is available in the project file. National Forest system and non-system roads currently occupy up to approximately 17.5 percent of any units, as shown in the Existing Disturbance column of Table 3, which includes system roads, remnant logging roads (skid trails), and landings. Non-system roads with ghost skid roads range from 0 to an estimated 8 percent of the units. Some temporary roads analyzed by resource specialists were not included in calculations of detrimental soil conditions when they were greater than 10 meters outside the unit boundary, approximately 0.6 miles were new in the proposed action. Landings proposed greater than 18 meters outside a unit boundary were similarly excluded from these calculations, none were new in the proposed action. Compaction on non-system roads, skid trails, and landings ranged from minimal to severe, with moderate to severe compaction being most prevalent on arterial logging roads, where observed. Three Swift units, , , and , have all of their detrimental soil conditions from non-system roads, skid trails, and landings but not from system roads. Table 3. Approximate extent of detrimental soil conditions (percent of units) Old Logging Swift Unit Number Unit Acres Roads & Skid Trails (%) Existing Disturbance 1 (%) % 11.1% % 12.9% % 12.3% % 11.3% % 10.4% % 10.3% % 10.9% % 10.1% % 9.9% % 11.8% % 11.5% 1 Includes logging roads and landings, unverified estimates of roads, and National Forest system roads. Swift Timber Sale Page 14

15 Table 3. Approximate extent of detrimental soil conditions (percent of units) Old Logging Swift Unit Number Unit Acres Roads & Skid Trails (%) Existing Disturbance 1 (%) % 14.2% % 10.6% % 13.3% % 9.9% % 7.5% % 10.6% % 10.4% % 8.9% % 9.9% % 10.2% % 10.1% % 17.5% % 8.7% % 10.9% % 11.1% % 11.3% % 9.0% % 9.4% % 10.0% % 11.8% % 10.8% % 11.4% % 10.7% % 3.4% % % % 5.3% % 6.4% % 9.8% % 7.7% % 8.1% % 5.9% % 12.8% % 5.0% % 7.2% % 5.4% % 11.1% Swift Timber Sale Page 15

16 Table 3. Approximate extent of detrimental soil conditions (percent of units) Old Logging Swift Unit Number Unit Acres Roads & Skid Trails (%) Existing Disturbance 1 (%) % 9.4% % 6.3% % 5.1% % 4.0% % 10.4% % 11.4% % 8.6% % 8.6% % 10.2% % 6.6% % 11.8% % 7.5% % 3.5% % 9.4% % % 7.1% % 11.6% % % 10.3% % 14.0% % 5.5% % 6.0% % 3.7% % 10.1% % 7.1% % 7.2% % 6.3% % % 13.1% % 5.3% % 9.6% % 11.3% % 11.6% % 7.8% % 10.7% % 9.7% % 4.9% Swift Timber Sale Page 16

17 Table 3. Approximate extent of detrimental soil conditions (percent of units) Old Logging Swift Unit Number Unit Acres Roads & Skid Trails (%) Existing Disturbance 1 (%) % 8.8% Maximum 8.1% 17.5% Slope Stability A Forest Service soil scientist visited units which contained Soil Resource Inventory mapping (Wade 1992) of potentially unstable slopes (Appendix A Soil Mapping). Land managers conservatively delineated unstable and potentially unstable areas as riparian reserves until field-verification could occur. A qualified earth scientist can update the soil mapping designations with field verified interpretations. The project scale analysis corrected SRI mapping in a few places, and will eventually correct the corporate GIS map data. Gifford Pinchot National Forest GeoHaz GIS layer identifies active and past-active landslides (USDA 1999) within the Project Area. Field verification indicated isolated, actively moving landslides in or near Swift Units , , (Figure 1, Tiles 9 and 11) and (Figure 1, Tiles 27, 29). One area in Swift Unit was relatively larger (Figure 1, Tile 9). Actively unstable soils will be buffered to exclude the moving landslide from vegetation management. The Soil Resource Inventory identifies approximately 120 acres of potentially unstable areas in Swift Units (Figure 1, Appendix A Soil Mapping) that include SMU 57 (Figure 1, Tile 2), 87 (Figure 1, Tile 20) and 8387 (Figure 1, Tiles 22-29) and a High Risk rating for Natural Stability as described below. This analysis shall serve to document changes to the rating of soils within the units listed. Natural Stability Risk Rating Gifford Pinchot National Forest NEPA Assistance for the Soil Resource (Wade, et. al. 1992b) classified SRI Natural Stability ratings from Low Risk to Very High Risk as defined below. The SRI defines the Natural Stability rating as based on the relative stability of the mapping units as they occur in the natural state. This includes any movement or loss other than surface erosion, by slumps, slides and all kinds of deep-seated failures (Wade 1992). a. Very High Risk Generally, Class IV or V Natural Stability Rating. Sometimes designated as unsuited (for timber management) and removed from timber base via GP FSH , Chapter 20 when the SMU is given a suffix "F, and thus is taken out of the timber base per the Timber Land Classification. [This does not apply to any units of the Swift Timber Sale.] b. High Risk Generally, Class IV or V Natural Stability Rating. May be unsuited - has most of the characteristics of slumps and landslides 2 ; some timber harvest may occur by individual tree selection, small group selection, or very small CC [Clear Cut]; generally, no roads should be built in these areas - involve Geotech Group and Soil Scientist. These specialists may more accurately map the area and help develop the necessary documentation to move the area to the Very High Risk by GP FSH [Applies to 4 units, as listed in Table 4, below.] 2 Characterized by erratically leaning trees, slumping topography with bare headwalls, sag ponds and over-steepened pressure ridges, tension cracks; often with riparian vegetation, seeps, and ponds. Swift Timber Sale Page 17

18 c. Moderate Risk Generally, Class III or IV Natural Stability Rating. Some characteristics of slumps and landslides are evident, careful road location and sale design will allow some timber harvest - involve Soil Scientist. [Applies to 5 units listed in Table 4, below.] d. Low Risk Class I, II, and III Natural Stability Rating. Few if any characteristics of slumps and landslides are present, planned timber harvest design to fit the ground situation can take place. Remember to consider other interpretations. [Applies to all remaining units of the proposal.] Soil Natural Stability in Soil Map Units (SMU) 3157, 59, 5923, 87, 8287, and 8387 Forest Soil Scientist professional judgment is that the timber harvest prescriptions, as proposed in the action alternative, would mitigate landslides initiation in those units listing a regular thin or gap avoidance (Table 4). Some units were field verified by a soil scientist and had few if any existing characteristics of mass wasting. Aquatics technicians and specialists also visited units and noted unstable areas which have been incorporated into this analysis. Recommendations for management in stands with unstable slopes include a modified thinning prescription (no gaps) and a road construction or reconstruction plan that avoids entering the unstable area, as specified in Mitigation Measure 5. Only Unit proposes new temporary road construction near potentially unstable soils. Project design will include avoiding harvest on steep slopes along the north unit boundary of Unit , , and on SMU 87 and Table 4. Slope Stability Project Design Features and Mitigations in Swift Units Swift Unit Acres mapped unstable Potentially Unstable SMU Tile (Page) Number on Soils Map Field visit to verify active landslides presence or absence SRI Natural Stability Rating Soil Scientist, Aquatics survey Soil Scientist, Aquatics survey Aquatics survey Aquatics survey Moderate Moderate Moderate High Design feature or mitigation Moderate thin, careful road location and sale design will allow some timber harvest - involve Soil Scientist. Standard thin, careful road location and sale design will allow some timber harvest - involve Soil Scientist. Most of risky area included in riparian no-cut buffer. Avoid small area, which is included in riparian no-cut buffer Early seral candidate with full or modified riparian buffer. Avoid steep areas, none likely to exist. Swift Timber Sale Page 18

19 Table 4. Slope Stability Project Design Features and Mitigations in Swift Units Swift Unit Acres mapped unstable Potentially Unstable SMU Tile (Page) Number on Soils Map Field visit to verify active landslides presence or absence SRI Natural Stability Rating Soil Scientist, Aquatics survey Soil Scientist, Aquatics survey Soil Scientist, Aquatics survey Soil Scientist, Aquatics survey Soil Scientist, Aquatics survey Soil Scientist, Aquatics survey High Moderate Design feature or mitigation Standard thin, careful road location and sale design will allow some timber harvest - involve Soil Scientist. Moderate thin, careful road location and sale design will allow some timber harvest - involve Soil Scientist. High Avoid slopes > 45% on north half of unit High Avoid slopes > 45% on north edge of unit High Moderate Moderate thin, careful road location and sale design will allow some timber harvest - involve Soil Scientist. Judged actively unstable, avoid (generally slopes > 45% on north edge of unit) Summary of Existing Condition Existing detrimental soil conditions in the project area have reduced soil productivity in the long term (greater than fifty years). Soils within the project area were soils formed in volcanic ash and pumice from Mount St. Helens, Mount Adams, and other sources, although glacial till is the dominant parent material on some gentler slopes, over residual or colluvial weathered bedrock materials of volcanic origin. Ground-based timber harvest have altered soil properties and potentially decreased soil productivity in the planning area. Damage to soil physical properties on skid trails and landings has recovered over time, but management activities did reduce soil quality where ground-based skidding operations displaced organic surface layers or caused deep compaction. The analysis estimates existing detrimental conditions within the 20% Forest Plan Standard for detrimental soil conditions (USDA 1990) in the 86 activity areas. Compaction on old logging roads, skid trails, and landings ranges from minimal to severe, with moderate to severe compaction being most prevalent on arterial logging roads. Swift Timber Sale Page 19

20 Field investigations revealed a feature indicating mass wasting in Swift Units , , , , and that the Forest GeoHaz corporate GIS layer (USDA 1999) did not delineate. Five units contain an SRI Natural Stability Risk Rating of High, and 5 other units contain an SRI Natural Stability Risk Rating of Moderate (Wade, et. al. 1992b). Risk from recently discovered features and the High rating area would be mitigated with measures such as exclusion from harvest as riparian reserves. Desired Future Condition (DFC): Soils on system and some non-system roads and landings will not likely return to pre-harvest conditions in the foreseeable future. A reference condition may relate some of the main benefits of the soils resource to discussions of management activity effects. The Soil Management Objective is to maintain or enhance soil productivity by avoiding long-term detrimental physical and biological soil conditions. Environmental Consequences Alternative A No Action Direct Effects/ Indirect Effects There are no direct effects of choosing the no action alternative. No further losses or gains in soil productivity in the short term or long term are expected in this alternative, other than from unrelated activities of other forest management such as trail maintenance, or extraction of special forest products. Detrimental conditions in the units would remain, the extent ranges from 0 to 20% with the exception of two small units in any of the units (Table 3). Existing National Forest system roads and landings would not be restored and would remain in a detrimental condition for the foreseeable future. Recovery of soil productivity would be slower with no action than the proposed action in those areas that would be subsoiled and amended after their use, and the time needed to reach the desired future condition would take longer without the treatment. Detrimental soil compaction and displacement would remain localized to existing system and non-system roads, trails and landings. No actions are currently planned to address unauthorized roads in the area, however some decommissioning or restoration of authorized and unauthorized road opportunities exist. Environmental effects of these opportunities would be analyzed in this document under the proposed action, since there are no near term plans to analyze them outside of this proposal. In the long term, soil quality may continue to improve to allow site productivity to return to levels before disturbance by management actions, but the rate would largely be dependent on vegetation roots growth, the resilience of the soil and intensity of the disturbance. Soil displacement and erosion on skid roads would last long term because soil formation is a slow process. Timber Harvest The No-Action Alternative would involve less ground disturbance than the Action Alternative (Table 5). No increase in detrimental soil conditions in the units would occur and no change in soil productivity due to logging related compaction and displacement would occur. Existing non-system logging roads and landings would not be used or restored, and would likely remain in a detrimental condition for the foreseeable future. Swift Timber Sale Page 20

21 Slope Stability The risk of management-induced landslides would continue to be low, related only to past, present, or future actions listed in Table 8. Cumulative Effects of No Action Alternative No cumulative effects to soil productivity would occur because there would be no increase in the amount of detrimental soil conditions in the long term. The no-action would not involve increasing the permanent transportation system. Foreseeable management activities would be similar to the proposed action alternative. Summary of Effects There are no direct effects of choosing the no action alternative. No further losses or gains in soil productivity in the short term or long term are expected in this alternative. The risk of managementinduced landslides would continue to be very low. The rate size or number of mass wasting events would not change with the no-action alternative. Alternative B Proposed Action Direct Effects/ Indirect Effects Direct effects due to soil disturbing activities would occur on site and affect only the immediate areas where soils are compacted, displaced, or severely burned. Potential effects of the proposed activities on soil productivity are due to compaction, puddling, displacement, erosion, severe burning and loss of soil organic matter. The calculations of detrimental conditions related to Timber Harvest below include the calculations applicable to the Forest Plan Standards and Guidelines (USDA 1990). Timber Harvest No additional losses in soil productivity due to ground based equipment travel are predicted in any of the units. Unit would have the highest amount of new disturbance from the proposed action, up to approximately 19.4 percent soil disturbance due to non-system roads, skid trails, and landings from ground based logging systems (Table 5). Project design criteria and mitigation measures would minimize and restore soil compaction and displacement, as specified in Mitigation Measures 2, 3, 4, 5, 6, 7, and 9, so that detrimental conditions would not remain long-term. Between 2.9 and 19.4 percent of the unit areas would be temporarily compacted or displaced by system and non-system roads and landings. Existing landings and non-system roads that are not used for Swift Timber Sale would not be restored, and would likely remain in a detrimental condition for the foreseeable future. Table 5. Prediction of detrimental conditions of conceptual road and landing construction No Action, Alternative A, (%) Action Alternative B, (%) Estimated Unit disturbance - Potential Cumulative Effects (without mitigations) Same as existing condition 2.9 to 19.4, (2.9 to 15.5 with Percent Increase in Unit disturbance Same as existing condition (0%) restoration) 0 to 7 Swift Timber Sale Page 21

22 Generally, the duration and intensity of effects from skid trails is less than temporary roads and landings, but the extent is greater. Measures such as subsoiling and re-vegetation are intended to restore productivity, further reducing the extent of effects. Skid trails would not create detrimental soil conditions greater than 7 percent of the units with Project Design Criteria and Mitigation Measures, # 4, designating skid trails at 150 feet apart, and are not expected to result in losses in soil productivity. In general, the intensity of losses in soil quality would be relatively low in skid roads, temporary roads and landings (Table 6) compared to the existing conditions. The losses in soil quality would be decreased by the mitigation measures and design features that subsoil and restore those areas. This would translate to similar effects on soil productivity. Table 6. Magnitude, Duration and Intensity of Losses to Soil Quality and Productivity (from detrimental conditions) by Alternative Intensity of Soil Productivity Duration Loss Magnitude (Extent) Short term, No Action None None Alternative Short term soil quality, Proposed Action Skid roads: Low to Moderate increases Skid roads: Unknown, likely less than 7% in any unit. Long term, (more than 50 years), No Action Alternative Long term soil productivity, (more than 50 years), Proposed Action Temporary Roads and Landings: Low increase post-logging due to mitigation measures None Skid roads: Low increases that have lessened with time. Temporary Roads and Landings: Low increase post-logging due to mitigation measures Temp Roads and Landings: Low increase post-logging due to mitigation measure None Skid roads: Likely low, less than short-term extent. Temporary Roads and Landings: Low increase post-logging due to mitigation measure, less than short-term extent. Locally concentrated losses in soil quality would occur in the short term due to additional compaction and displacement caused by ground-based equipment on skid trails, roads and landings. Forty nine of the Swift stands include new temporary road or landing construction from the proposed action, estimated at less than 7 percent of any unit with the prescribed logging system design (Table 7). Table 7. Cumulative detrimental soil conditions (percent of units) Reconstruction of Non-system Roads (Acres) Construction Disturbance from New Temp Roads and Landings (%) Cumulative Effects, Including Existing Roads, Landings, Construction and Reconstruction (%) Unit Swift Unit Acres Swift Timber Sale Page 22

23 Table 7. Cumulative detrimental soil conditions (percent of units) Reconstruction of Non-system Roads (Acres) Construction Disturbance from New Temp Roads and Landings (%) Cumulative Effects, Including Existing Roads, Landings, Construction and Reconstruction (%) Unit Swift Unit Acres Swift Timber Sale Page 23

24 Table 7. Cumulative detrimental soil conditions (percent of units) Reconstruction of Non-system Roads (Acres) Construction Disturbance from New Temp Roads and Landings (%) Cumulative Effects, Including Existing Roads, Landings, Construction and Reconstruction (%) Unit Swift Unit Acres Swift Timber Sale Page 24

25 Table 7. Cumulative detrimental soil conditions (percent of units) Reconstruction of Non-system Roads (Acres) Construction Disturbance from New Temp Roads and Landings (%) Cumulative Effects, Including Existing Roads, Landings, Construction and Reconstruction (%) Unit Swift Unit Acres Number of units affected Max % 7% 19.4% Mechanical Processing on Steep Slopes The Proposed Action proposes ground based equipment travel with mechanical cutting and harvesting machines on slopes mapped by the SRI that are not rated as permitting ground based logging (Wade, et. al., 1992). Direct effects to soils due to mechanical processors on slopes up to 45 percent are expected to be similar to those on 30 percent slopes, judging by the amount of area affected and intensity of soil displacement and compaction. Soils that are potentially affected by this activity are located in 22 units listed in Table 9. Minor amounts of area within affected units would have the potential for minor displacement of topsoil along the travelled routes. Use of mechanical cutting and harvesting machines on steep slopes can increase the risk of erosion losses due to soil displacement, however the probability of its occurring is low because of design features and the following mitigation measures. These measures would specify that equipment operate on a slash mat of tree limbs and tops where possible to limit soil compaction and displacement, to protect the topsoil for vegetative growth, and provide water infiltration (Mitigation Measure 2), require erosion treatment where gouging or soil displacement occurs from logging systems, in order to prevent rill and gully erosion and potential sediment delivery (Mitigation Measure 3), require sale administrators to monitor equipment activity on steep slopes in order to prevent and rectify potential resource damage (Mitigation Measure 8), and limit ground-based equipment logging with mechanical cutting and harvesting machines to slopes less than 45 percent on steep slopes (Mitigation Measure 9). Swift Timber Sale Page 25

26 Professional judgment and peer opinion suggest that the mitigation measures would be sufficient to protect the soils resource. Effects of Management Activity on Slope Stability Based on professional judgment, the risk of triggering a management-induced landslide is low in all units of the Swift Timber Sale because of the inherent relatively low to moderate risk (Table 4) combined with avoidance of vegetation management and temporary road construction in high risk unstable soils. The ratings discussed in the Existing Condition section Natural Stability Risk Rating are related to Natural Stability, based on the relative stability of the mapping units as they occur in the natural state, whereas the rating discussed in the Environmental Effects section is related to an expected mass movement due to management activities. Management recommendations include a thinning prescription that retains a living, tree root structure across the unit, which is included as a design feature of proposed action, and a road construction or reconstruction plan that avoids entering the slump area, as specified in Mitigation Measure 5. The risk of triggering a mass wasting event is low, based on professional opinion because no new temporary roads are proposed on these soils and the silviculture prescription of the proposed project is a standard or moderate thin whereas the SRI risk ratings presumed clear cutting as the silviculture prescription, thus overestimating the risk. One factor in judging slope stability is previous response to regeneration harvest. Marginally stable soils that remained stable after regeneration harvests are likely to remain stable after thinning by the proposed action. Cumulative Effects The proposed activities (with incorporated Mitigation Measures and Design Features), in combination with past or reasonably foreseeable future actions on nearby federal land and adjacent private land, would not likely increase the amount of detrimental soil conditions in the long term. Cumulative losses in soil productivity due to management activities in the watershed are limited to permanent features, including National Forest system roads, non-system roads, landings and skid trails that are not subsoiled. The proposed action would not involve increasing the permanent transportation system. Swift Thin proposal will complement other proposed or current activities in the same subwatersheds, including ongoing precommercial thinning and invasive plant control; in-stream habitat restoration work, and road management associated with the Upper Lewis River Pilot Roads project. Restoration projects identified during the planning process are: Along FR 3211, within Unit ; a ditch relief culvert crossing an unnamed tributary of Rush Creek is plugged and restoration is required Along Forest Road 31, on approach to Unit #103195; identified ten 15-inch ditch-relief culverts for replacement with 18 culverts. Table 8. Actions Considered in Cumulative Effects Analysis Action Description Date Past Recent large fires Fire regeneration of stands from Smokey Creek and Twin Buttes fires may have reduced levels of organic matter on severely burned areas Early 1900s Swift Timber Sale Page 26

27 Table 8. Actions Considered in Cumulative Effects Analysis Action Description Date Timber harvest within Table 2 lists managed stands that were clear-cut harvest, and adjacent to the units followed by planting. Present and Ongoing National Forest System roads Maintenance and management of system roads on lands within the listed Sub-Basins occupy areas not available as productive forest. Relatively high density, but within Forest Plan S&G s Ongoing Special forest products harvest Forest Trails, unauthorized trails Dispersed recreation Road Decommissioning Global climate change effects for soil productivity in most cases. Commercial harvest, sale and free use of forest products create soil disturbances away from system roads and may introduce contaminants and invasive species. Relatively low extent and effect in these watersheds. Management of forest trails including erosion work, route signing, and maintenance. Minimal extent and effect in these watersheds. User-created trails and dispersed recreation disturb soils and reduce soil quality. Minimal extent and effect in these watersheds. Future Upper Lewis Roads Pilot Project - restoration of roads. There is a potential for improvement of soil productivity in the long term over a relatively small extent. Significant changes to atmospheric conditions that could affect vegetation, soil temperature and moisture regimes, increased temperatures, and heavy precipitation events. Seasonal Ongoing Ongoing 2015 and later Ongoing, more expected Timber Harvest Losses in soil productivity on skid trails from the use of ground based equipment would be small to moderate in magnitude and duration, and cause relatively minor losses in soil productivity. Measurable losses in soil productivity are not expected. Thus, the proposed action would not cumulatively change soil productivity or the soil resource with proper implementation of mitigation measures and design features. Up to approximately 3.6 acres of any unit would have temporary roads and landings reconstructed or reused (Table 9), and up to 3 acres of new temporary roads and landings constructed. Restoration by subsoiling and planting, as specified in Mitigation Measures 4, 5, 6, and 7, would initiate recovery from compaction on temporary roads and landings, but would not return the soil to original conditions because of soil displacement. Localized soil displacement and erosion would be considered permanent because soil formation is a slow process, with hundreds of years or greater of development. This would likely not reduce soil productivity across the units because the adjacent soils and remaining subsoil layers would still be a suitable medium for tree growth. Swift Timber Sale Page 27

28 Table 9. Cumulative detrimental soil conditions due to logging activity (acres within units) Acres of Logging Swift Unit Number Acres of Temp Road and Landing Reconstruction or Reuse Systems NEW Construction (temporary roads and landings) Cumulative Logging Systems Disturbance (%) Foreseeable terrain for mechanical harvesters on steep slopes Yes Yes Yes Yes Yes Yes 3 Mechanized timber-harvesting equipment such as feller-bunchers. Swift Timber Sale Page 28

29 Table 9. Cumulative detrimental soil conditions due to logging activity (acres within units) Acres of Logging Swift Unit Number Acres of Temp Road and Landing Reconstruction or Reuse Systems NEW Construction (temporary roads and landings) Cumulative Logging Systems Disturbance (%) Foreseeable terrain for mechanical harvesters on steep slopes Yes Yes Yes (crossing to gentle ground) Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Swift Timber Sale Page 29

30 Table 9. Cumulative detrimental soil conditions due to logging activity (acres within units) Swift Unit Number Acres of Temp Road and Landing Reconstruction or Reuse Acres of Logging Systems NEW Construction (temporary roads and landings) Cumulative Logging Systems Disturbance (%) Foreseeable terrain for mechanical harvesters on steep slopes Yes Yes Max Soil Organisms In the long term, the action alternative combined with all past, present, and reasonably foreseeable management activities would not cumulatively affect localized populations of soil dwelling organisms in the units because populations of soil dwelling organisms would have recovered in the long term. Slope Stability The proposed activities (with incorporated design features), in combination with past or reasonably foreseeable future actions on nearby federal land and adjacent private land, are not likely to increase the frequency or magnitude of mass wasting events. It is conceivable that additional sediment from units would reach Rush, Drift, Calamity, or West creeks because of their proximity and slope position above the creek from a mass wasting event. This includes Swift Units , , , , and The likelihood of mass wasting is still low or moderate, but sediment from mass wasting events would be more likely to reach a major stream here than from other units of the planning area. Effects to water quality and aquatic species are addressed in the Fisheries and Hydrology sections of this analysis. Summary of Effects Measurable losses in soil productivity are not expected. Thus, the proposed action would not cumulatively change soil productivity or the soil resource with proper implementation of mitigation measures and design features. Up to approximately 3.6 acres of any unit would have temporary roads and landings reconstructed or reused (Table 9), and up to 3 acres of new temporary roads and landings constructed. The proposed activities are not likely to increase the frequency or magnitude of mass wasting events. Project Design Criteria and Mitigation Measures 1. Ground-based machinery will not be operated where soil water content is high enough to cause detrimental puddling, defined as when the depth of ruts or imprints is six inches or more (Forest Service Manual, Chapter 2520, R-6 Supplement No ). The objective is to limit the degree of detrimental soil rutting and puddling as well as reduce the potential for sediment delivery to streams. 2. Mechanical harvesters, when traveling away from approved skid trails or roads will operate on a slash mat of limbs and tops as thick and continuous as practical. Activity would be planned to make as few trips as possible. Off-road equipment shall not travel while bearing weight of trees Swift Timber Sale Page 30

31 (skidding). The objective is to limit soil compaction and displacement, to protect the topsoil for vegetative growth, and provide water infiltration. 3. Areas of gouging or soil displacement resulting from logging systems will be treated to prevent rill and gully erosion and potential sediment delivery to stream courses. Off road trails used for equipment fueling and servicing will be rehabilitated post use by moving the soil back to the natural contour of the hillslope (re-contour) and placing slash or vegetation on exposed mineral soils. Steep slopes will not be subsoiled to prevent further soil disturbance on steep slopes. Erosion control treatment may include, but is not limited to, repositioning displaced soil to restore the hillslope contour of disturbed sites, creating small ditches or diversions to redirect surface water movement, and scattering slash material to create flow disruption and surface soil stability. Erosion control measures will be implemented prior to the close of the timber sale. The objective is to prevent surface soil erosion resulting from timber related ground disturbance. 4. Forest Service will approve landings, skid trails and skyline corridors prior to timber felling. Skid trails must be located outside of all no harvest buffers, unless otherwise specified in unit specific project design features, where resource specialists have approved and marked a crossing. Skid trails will be spaced 150 feet apart. Skid trails will be re-established at previous skid trail locations, except where existing skid trails from prior entry are causing detrimental soil or hydrologic conditions that could be further avoided with alternative skid trail location. Skid trails will be subsoiled after use where compaction related to the project remains, with exceptions identified by the Forest Service. The soil profile will be shattered to the depth of soil compactions, the surface soil (topsoil) will not be mixed with subsoil, and available logging slash will be placed across the subsoiled surface. This measure will be accomplished immediately following logging activities. 5. Temporary roads will be located where past logging roads were located and avoid unstable slopes. If a new location would cause less resource effects than using an existing temporary road, then the newer road with less resource effects will be used to harvest the unit with line officer approval, who will work with an aquatics or soils resource specialist. Rock will be applied only where needed to reduce erosion, puddling and compaction. 6. Landings will be located where past landings were located, unless a new location would cause less resource effect or where no past landings were used to harvest the unit. New landings will be located outside of all no harvest buffers. Landings will be limited to the area needed for safe and efficient yarding and loading operations and have proper drainage. Certified weed free straw bale catchments or silt fences will be used to avoid sediment transport to road ditches or streams. The catchments will be located to intercept runoff from the landing prior to reaching any road ditch or stream. 7. Temporary roads and landings will be closed and restored after harvest and related activities are complete. Temporary roads and landings that were established for the timber sale will be ripped, de-compacted, or subsoiled to a depth of 18 inches (minimum). The result will be an uneven, rough surface without furrows, and be accomplished immediately following logging activities. De-compaction will encompass the entire landing and the sight distance (to discourage a bypass) from the beginning of the road, no less than 200 feet. The rest of the road will have drainage reestablished. Available logging slash will be placed across the de-compacted surface. No ground-based equipment will be operated on subsoiled portions of roads and landings after decompaction is completed to prevent re-compacting treated roadways and landings. Post-harvest motorized access to temporary roads will be prevented. Closure to vehicles is required to prevent subsoiled areas from being re-compacted, prevent erosion and sediment delivery, and to allow vegetation to develop. The objective is to rehabilitate areas compacted during management activities, accelerate recovery of compacted soils, and facilitate water infiltration and revegetation on those disturbed areas. These measures will also provide ground cover for exposed Swift Timber Sale Page 31

32 soils in order to reduce the potential for offsite erosion and maintain soil organic matter to prevent nutrient and carbon cycle deficits. 8. Periodic monitoring of ground-based activity on steep slopes will be performed by Forest Service in order to prevent/rectify resource damage that may occur because of mechanical cutting and harvesting machines. Resource damage includes forming of ponds, ruts, or rills; culvert blockages, stream channel instability, and the occurrence of scour or sediment transport and deposition downstream of cross drains. Project activities will be curtailed and corrective action taken, before work is allowed to resume, if resource damage is occurring. The objective is to minimize erosion and potential sediment delivery to streams. 9. Pre- bunching will be approved on a unit-by-unit basis on slopes greater than 35%, up to 45% slope, prior to start of operation. Mechanical cutting and harvesting machines will not operate over erosive soils on slopes greater than 35%, as shown on Unstable Soils map. The objective is to limit soil compaction and displacement, to protect the topsoil for vegetative growth, and provide water infiltration. The mechanical cutting and harvesting machine will: a. Be limited to slopes less than 45 percent, including short, steep pitches. b. Mechanical harvesters shall only travel downhill on steep slopes, when traveling away from approved skid trails or roads. Avoid traveling across the slope and turning on steep slopes. c. Equipment will operate on a slash mat of limbs and tops as thick and continuous as practical. d. Activity would be planned to make as few trips as possible. Off-road equipment shall not travel while bearing weight of trees (skidding). e. Not enter into riparian no harvest buffers (RMZ s) and unstable slopes, unless otherwise specified in unit specific project design features. 10. Over the snow operations: Ground-based equipment can operate on snow which is at least 2 feet deep, or a combination of 3 to 4 inches of compacted snow and soil frozen to at least 6 inches in depth. Operations shall not continue where snow does not provide protection; for example, if it rains heavily and the soil and snow become saturated. As an indicator, overnight temperatures should be less than 25 degrees F; afternoon daytime temperatures should not exceed 35 degrees F Monitoring Recommendations Mitigation Measure 8 specifies monitoring of ground-based activity on steep slopes, which Forest Service will perform in order to prevent and rectify resource damage that may occur because of mechanical cutting and harvesting machines. Resource damage includes forming of ponds, ruts, or rills; culvert blockages, stream channel instability, and occurrence of scour or sediment transport and deposition downstream of cross drains. Compliance with Forest Plan and Other Relevant Laws, Regulations, Policies and Plans Forest Plan Consistency The No Action and Proposed Action would meet the Forest Plan Standards and Guidelines in all of the units because restoration of compacted soils on old skid roads would occur in units where non-systematic remnant logging roads and skid trails exist, and new soil compaction would be mitigated, as described by Mitigation Measure 7, Temporary roads and landings will be closed and restored... Thus, the Proposed Action would not increase the percentage of detrimental soil conditions and would comply with the 20 percent Forest Plan Standard. Swift Timber Sale Page 32

33 Aldo M. Aguilar Soil Scientist, Gifford Pinchot National Forest Swift Timber Sale Page 33

34 References Aguilar, A.M Forest Plan Soils Guidelines Regarding Mechanical Harvesters on Gifford Pinchot National Forest. (Draft White Paper). Gifford Pinchot National Forest, Vancouver, Washington. Brown, G. W Landslide Damage to the Forest Environment. In: Swanston, Doug ed. Proceedings of a Workshop on Slope Stability: Problems and Solutions in Forest Management. U.S. Department of Agriculture, Forest Service, Pacific Northwest Forest and Range Experiment Station, Government Technical Report PNW-180. Busskohl, C. B Comm. Forest Soils Scientist. Umatilla National Forest S.W. Hailey Avenue, Pendleton, Oregon Froehlich, H. A.; Miles, D. W. R.; Robbins, R. W Soil bulk density recovery on compacted skid trails in central Idaho. Soil Science Society of America Journal. 49: Garland, J.J Designated Skid Trails Minimize Soil Compaction. The Woodland Workbook, EC Oregon State Univ. Extension Service. Haggerty, S Pers. Comm. Forest Soil Scientist. Olympic National Forest Highway 101 S., Quilcene, Washington Mahoney, R Silvicultural Decisions II: Mechanized vs. Conventional Logging. UI Extension Forestry Information Series I, FM12. [online]. Available: (Direct link: Products/Biomass Utilization and Small scale Logging Technology/Silvicultural Decsisions II Mechanized vs Conventional Logging.ashx. [November 19, 2012]. Nakae, J Swift Timber Sale Silviculture Resource Report. Zone Silviculturist. Gifford Pinchot National Forest, Mt. Adams Ranger District, 2455 Hwy 141, Trout Lake, Washington Napper, C.; Page-Dumroese, D.; Howes, S Soil-Disturbance Field Guide P. San Dimas, CA: U.S. Department of Agriculture, Forest Service, San Dimas Technology and Development Center. 112 p. Sidle, R. C Factors Influencing the Stability of Slopes. In: Swanston, Doug ed. Proceedings of a Workshop on Slope Stability: Problems and Solutions in Forest Management. U.S. Department of Agriculture, Forest Service, Pacific Northwest Forest and Range Experiment Station, Government Technical Report PNW-180. Soil Biology Primer [online]. Available: [November 8, 2012]. Soil Survey Staff, Natural Resources Conservation Service, United States Department of Agriculture. Skamania County Web Soil Survey. Available online at [November 8, 2012]. Swift Timber Sale Page 34

35 Swanston, D. N Slope Stability Problems Associated with Timber Harvesting in Mountainous Regions of the Western United States. U.S. Department of Agriculture, Forest Service, Pacific Northwest Forest and Range Experiment Station, Government Technical Report PNW-21. U.S. Department of Agriculture, Forest Service, Pacific Northwest Region Gifford Pinchot National Forest Soil Resource Inventory. U.S. Department of Agriculture, Forest Service Land and Resource Management Plan, as amended. Gifford Pinchot National Forest, Vancouver, Washington. USDA Forest Service, Gifford Pinchot National Forest, Mt. Saint Helens Ranger District. xxxx. Watershed Analysis. xxx pp. Amboy, Washington. USDA Forest Service, Gifford Pinchot National Forest Unpublished GIS layer. Geologic hazards (gpghz). Vancouver, Washington. USDA Forest Service, Gifford Pinchot National Forest. 1999b. Landtype Association (gplta). Vancouver, Washington. USDA Forest Service, Gifford Pinchot National Forest. 1999c. Potential natural vegetation zones (gppvg). [online]. Available: [November 8, 2012]. USDA Forest Service, Pacific Northwest Region Forest Service Manual, Chapter 2520, R-6 Supplement No USDA Forest Service, USDI Bureau of Land Management Record of Decision for Amendments to Forest Service and Bureau of Land Management Planning Documents Within the Range of the Northern Spotted Owl. Portland, Oregon. USDA Natural Resources Conservation Service Introduction to Microbiotic Crusts. Soil Quality Institute; Grazing Lands Technology Institute. USDA Natural Resources Conservation Service Soil Quality Institute. Soil Biology: Key Educational Messages. [online]. Available: [November 8, 2012]. USEPA Climate Change Health and Environmental Effects Forests [online]. Available: [November 8, 2012] Wade, J.; Herman, L.; High, C. T.; Couche, D Soil Resource Inventory. Gifford Pinchot National Forest. Vancouver, Washington. Wade, J.; High, C. T. 1992b. NEPA Assistance for the Soil Resource. Gifford Pinchot National Forest. Vancouver, Washington. Swift Timber Sale Page 35

36 Appendix A Soil Mapping The Soil Resource Inventory (Wade, et. al., 1992 and USDA FS, 1971) soil mapping units (SMU) were modified for accuracy at the project scale, reflecting field observations and GIS analysis (Figure 1). Table 10 is an index of the page numbers, called tiles, in the soils map. For example, Swift Unit is found on page 9 of the soils map in Figure 1. Readers of the Microsoft Word format of this report can double-click the electronically embedded maps to open them in a PDF viewer such as Adobe Acrobat Reader. (Double-click to open PDF Document) Figure 1. Unstable Soils Mapping (SRI) and Logging Systems Conceptual Design Swift Timber Sale Page 36

37 Figure 2. Soil Mapping (SRI) with Soil Map Unit numbers Swift Timber Sale Page 37