Soils Specialist Report

Transcription

1 Soils Specialist Report Lex Vegetation Management Project Environmental Assessment Bend/Ft. Rock Ranger District Deschutes National Forest Deschutes County, Oregon Prepared by: /s/ Peter Sussmann Date: November 15th, 2017 Peter Sussmann Soil Scientist Deschutes National Forest 1

2 Introduction Interpretations and descriptions of the soil resource in this report are derived primarily from the Soil Resource Inventory (SRI) for the Deschutes National Forest (Larsen, 1976) and digital spatial data in the corporate Geographic Information System (GIS). Topographic maps, aerial photographs, silvicultural reports, field-based reconnaissance, sampling and agency directives were also used to characterize local conditions and analyze environmental consequences of the proposed actions and developed alternatives. Actions analyzed include timber harvest activities to implement proposed silvicultural and forest health treatments, vegetation control, road management activities, mechanical fuels reduction, and prescribed fire treatments. Location The LEX Project area is on the Bend/Ft Rock District of the Deschutes National Forest and generally covers a 15 square mile area southeast of the intersection of Forest 45 and the Cascade Lakes Highway (Deschutes County 46). The area lies within portions of the Fall River - Deschutes River (HUC # ) and North Unit Diversion Dam - Deschutes River (HUC # ) 10 th field Hydrologic Units and portions of the Dutchman Creek (HUC # ), Spring River (HUC # ), Town of Sunriver - Deschutes River (HUC # ) and Benham Falls -Deschutes River (HUC # ) 12 th field Hydrologic Units. Climate Climate of the area is generally characterized by cold moist winters and hot dry summers. Average total precipitation is approximately 50 inches (OSU 2011), with about 54 percent of annual precipitation falling during the winter months. Total average snowfall in the project area is about 100 inches for the period of record, and a persistent winter snowpack averaging 3 to 6 feet in depth typically develops (WRCC 2011). Convective thunderstorms are fairly common during late spring and summer, occurring on average approximately 14 times a year in this part of the Cascades. Frost can occur any time of the year in the project area (WRCC 2011). Landforms and topography The project area is within the Bachelor Butte physiographic area identified in the Deschutes SRI and is best described at the Level IV Ecoregion scale as Unit 9b - Grand Fir Mixed Forest. Landform Associations (LFAs) described within the area include Lava Flows and Glaciated Volcanoes with Mountain Hemlock and Grand Fir-White Fir Association (LTA) subgroups. 2

3 Primary landforms within the area are volcanic cinder cones and glaciated uplands. Glacial deposits overlay igneous rocks of various ages on the relatively gentle uplands, which generally slope to the south/southwest between the buttes. Dutchman Creek, although not a perennial stream, is the only defined drainage-way within the project area due to the highly porous nature of the soils and bedrock in the area. Elevations range from approximately 6,100 at the top of buttes and in the northwestern portion of the project area to 4,900 feet along the southern extent. Distribution and Characteristics of Soils Soil types from the Deschutes National Forest SRI were grouped based upon parent materials and landform to form more descriptive mapping units at the Association (LTA) scale. Table_1 displays these general soil groupings and their relative proportions in the project area. The soil groupings are also displayed spatially (Figure_1). Table_1. General Extent of LTA Soil Groups in the LEX project area LTA Soil Groups Percent of Project Area Coarse ash over glacial deposits gentle to moderate slopes 54 Coarse ash over residuum gentle to moderate slopes 25 Cinder Cones moderate to steep slopes 11 Ash over volcanics (Mt. Hemlock vegetation type) 4 Lodgepole Basins 3 Lava Flows 2 Tuff Ridges <1% Parent Materials Soils across the project area have developed in a moderately deep surface mantle of volcanic ash and pumice ejected from Mt Mazama around 7,700 years ago. Subsurface soils have developed in parent materials derived from glacial deposits, basaltic lava flows, pyroclastic tuffs, or cindery colluvium. Overall, soils have undergone relatively little weathering and development but contain enough available nutrients and organic matter to support forest, shrub and grass plant communities. 3

4 Figure_1. Map of LTA Soil groups in the Lex Project Area. Characteristics The soil profiles of surface ash and pumice vary in depth from about 1 to 3 feet, although shallower phases are present. Surface soil horizons are primarily loose (non-cohesive), highly porous, very permeable and well drained with medium to coarse sandy loam textures and comparatively low bulk densities. The moisture regime is udic (moist) and the temperature regime is cryic (cold) throughout the project area. Subsurface soils are typically gravelly or rocky. A horizon depths range between 2 and 4 inches and the depth of undisturbed organic litter and duff is variable by aspect and length of time since fire disturbance. Productivity Soil productivity in the project area is strongly correlated to annual precipitation and water holding capacity of the soils, although topographic position, elevation, and aspect also play a role. Soil productivity is moderate across the majority (61%) of the area as a result of adequate precipitation, soil depth and textures favorable to providing and storing plant available water. However, the length of season during which water and nutrients are available for uptake is limited by soil temperatures in the project area that do not warm until late spring and moisture regimes that dry out by mid to late summer. 4

5 Sites expressing the highest productivity (about 22% of the project area) are located on cinder cones or lower elevation areas where annual precipitation, water retention and water availability are the greatest. These sites support mixed conifer stands with multiple pine and fir species where soils are deep, consisting of 1 to 3 feet of Mazama ash over cinders, buried finer textured soils (residuum) or glacial till. Finer textured subsoils within reach of tree roots provide additional plant available water for uptake longer into the growing season. Sites exhibiting the lowest productivity are generally located higher in elevation on flatter or basin type terrain where cold air tends to settle and limit soils from warming early in the season. These areas are primarily lodgepole pine dominated sites where soils are moderately deep or shallow and consist of ash over glacial till or other volcanic materials. Permeability of both the surface and subsoil is rapid or very rapid, combining to make these soils droughty. Other low productivity areas include uneven and broken lava flows, and several butte tops or upper side slopes consisting of coarse pumice or cinders. Susceptibility to management actions The ash-mantled soils in the project area are variably susceptible to surface erosion, compaction, and displacement. The inherent surface erosion potential of these soils is low to moderate, depending on the severity of slope, and is primarily attributed to their sandy textures, high permeability and high infiltration rates. The susceptibility to compaction is also low to moderate, primarily due to their low bulk density and the coarse to medium textures in the profile. These characteristics also allow for a degree of natural recovery over time from compaction due to freeze-thaw action, root penetration, good drainage, and the activity of soil fauna and macrobiota. The susceptibility to displacement is moderate to high depending on moisture status and slope. When dry, the topsoil of ash-mantled soils or pumice is easily displaced by ground disturbance, particularly on steep slopes. The lowest productivity soils in the project area are the least resilient to management, although they are not overly sensitive to ground disturbance such as compaction or displacement. Excessive losses of surface organics and effective ground cover can diminish their site productivity due to the inherently cold nature of these sites. Litter and duff layers on these sites are important for the retention of soil moisture and as a substrate to beneficial soil biota such as symbiotic mycorrhizal fungi, both of which are key factors in maintaining site productivity on these sites. 5

6 Response to fire Ash soils can develop hydrophobic conditions as a result of high temperature and long duration fire conditions. Intense heat can alter certain organic components in the soil and create a water repellant (hydrophobic) layer within the soil profile capable of increasing overland flow and accelerating surface erosion during rain events (DeBano 1981). Sites with snowbrush (Ceanothus species) and green-leaf manzanita in the shrub component provide a combustible source of organic compounds that can be converted and re-deposited as a hydrophobic layer below the soil surface after wildfire. Dense mixed conifer stands are also vulnerable to this process where thick organic layers have developed on the soil surface. The loss of organics on the soil surface following fire can also reduce the moisture holding capacity of the site in the short term, although the initial flush of nutrients in the from the combustion of organics and release of nitrogen can initiate and support the re-growth of forbs, shrubs and trees on site. Soil Functions Soil quality in the project area is favorable for supporting forest ecos and associated land uses. The ash mantled soils function to provide a number of important eco processes as a result of their properties and productivity. Soils serve as a growing medium that stores water, cycles nutrients, and furnishes habitat for beneficial soil biota and symbionts. They also moderate flux through filtering and buffering, produce biomass, and support and regenerate a contiguous forest cover capable of yielding fully stocked forest stands. Sensitive Soil Types The Deschutes Land and Resource Management Plan (LRMP) directs the identification and protection of sensitive soil types during the planning and implementation of proposed projects that use mechanical equipment (Deschutes LRMP, p. 4-70). Sensitive soils are less resilient to management activities and are slower to recover following ground disturbances such as compaction and displacement. As a result, long-term site productivity can be easily diminished on sites where these soils are located and maintaining or enhancing their intrinsic productivity often requires conservation or restorative actions. Although ash soils are relatively resilient and not overly sensitive to ground disturbance, there are soil groups in the project area whose sensitivity, limitations, and resilience affect their ability to recover from mechanical disturbance. Sensitive soil types in the LEX planning area include lava flows with shallow soils, cold air basins with limiting soil temperatures, and steep slopes (>30%). Table_2 displays the sensitive soil types and their relative extent in the LEX planning area. 6

7 Table_2. Sensitive Soil Types in the LEX planning area Sensitive Soil Types Percent of Project Area Forested lava flows with shallow soils 2 Cold air basins gentle slopes 3 Buttes moderate to steep slopes 11 Total 16 Soils sensitive to disturbance are present on approximately 16 percent of the LEX project area (Figure_2). Figure_2. Map of Sensitive Soil Types in the Lex Project Area 7

8 The sensitive soil types identified in the project area are further described as follows: Forested lava flows associated with the Bachelor Butte volcanic chain are present along the western boundary of the project area. These features are covered by a relatively an ash cap of variable depth and forested with a mixture of lodgepole pine, ponderosa pine and fir species. Shallow soils on these features are sensitive to compaction and displacement, but the capability, productivity, sensitivity, and resilience of these features are highly variable due to the heterogeneous nature of the ash cap depth and rock outcrops. Although highly broken lava flows are unsuitable for management and typically excluded from forest management activities, there is a sufficient ash cap on much of the area mapped as lava flows conducive to selective mechanical harvest under some operating restrictions. Cold air basins are present as gently sloped or low lying depressions in the north central portion of the project area. Steeper temperature gradients between the soil surface and air column in these areas lead to more frosts during the growing season and favor more resistant lodgepole pine seedlings during regeneration. These areas are particularly prone to the loss of organic material when disturbed, resulting in droughty conditions and a reduction of soil biota essential for nutrient conversion on cold sites. Resilience to ground disturbance is low in these areas since the litter, duff, and topsoil horizon are relatively thin and easily displaced by management activities. As a result, the inherent productivity after disturbance can be diminished for the long-term without some mitigation. Steep slopes are present on buttes within the project area. Soil depths on moderately steep to steep (>30%) slopes are generally shallower on the upper third of these slopes and deeper on the mid and lower elevations of the buttes. Northern and eastern aspects maintain higher levels of organic carbon and surface litter and duff, compared to southern and western aspects, and are generally more resilient to management disturbances. Southerly and westerly aspects have less surface litter and duff and are particularly susceptible to brush invasion following disturbance. The coarse cinder colluvium or mixed cinders and ash that comprise soils on the buttes are highly sensitive to displacement due to the loose (non-cohesive) nature of this material. Although the coarse surface texture and high permeability rates result in moderate surface erosion potentials, these characteristics also make them highly susceptible to displacement from machine traffic, especially when travelling across the slope. Topsoil and organic horizons can easily be truncated from subsurface horizons. As a result, soils on the buttes are considered to have moderate to low resilience to management activities. 8

9 Management Direction The Deschutes Land and Resource Management Plan (LRMP) includes Forest-wide standards and guidelines that direct land management activities to promote the maintenance or enhancement of soil productivity. Forest Standards and Guidelines applicable to this project include: 1) leaving a minimum of 80 percent of an activity area in a condition of acceptable productivity potential following the implementation of proposed activities (Forest Plan Standard and Guidelines SL-1 and SL-3; p. 4-70); 2) the use of rehabilitation measures when the cumulative impacts of management activities are expected to cause damage exceeding soil quality standards and guidelines on more than 20 percent of an activity area (SL-4); and 3) limiting the use of mechanical equipment in sensitive soil areas (SL-5). The Pacific Northwest Region developed soil quality standards and guidelines to limit detrimental soil disturbances associated with management activities (FSM 2520, R-6 Supplement No ). This guidance is consistent with Deschutes LRMP interpretations for standards and guidelines SL-3 and SL-4 that limit the extent of detrimental soil conditions within activity areas. Region 6 guidance supplements the Forest LRMP standards and guidelines designed to protect or maintain soil productivity and provides policy for planning and implementing management practices which maintain or improve soil quality. Specifically, this supplement includes the following guidance when initiating new activities: 1. Design new activities that do not exceed detrimental soil conditions on more than 20 percent of an activity area. (This includes the permanent transportation ). 2. In activity areas where less than 20 percent detrimental soil impacts exist from prior activities, the cumulative amount of detrimentally disturbed soil must not exceed the 20 percent limit following project implementation and. 3. In activity areas where more than 20 percent detrimental soil conditions exist from prior activities, the cumulative detrimental effects from project implementation and must, at a minimum, not exceed the conditions prior to the planned activity and should move conditions toward a net improvement in soil quality. 9

10 Existing Condition Soils within the project area have been variably affected by natural disturbances and past management activities. Wind throw of trees and fire are the primary natural disturbance mechanisms that can affect the soil resource but neither have occurred to a great extent in the recent past. Although not extensive, isolated wind throw is present throughout the area, primarily due to the high elevation locations susceptible to winds and coarse textured soils that dry out for much of the year. Fire historically was a regular disturbance mechanism in the area but suppression activities have limited the extent of this disturbance and associated effects to the soil resource over the last 100 plus years. Prescribed fire has occurred within some portions of the project area in more recent years with little to no effect on the mineral soil characteristics. Management activities such as timber harvest, road building and recreation have had varying degrees of impact on the soil resource within the project area. Many proposed treatment units have had prior entries for harvest and fuels reduction purposes. These activities utilized ground based machinery to cut and remove commercial material and pile slash generated during the process. Most roads, skid trails and landings created to support these activities have levels of compaction that meet detrimental disturbance definitions included in the Region 6 supplement to the 2520 Forest Service Manual (R-6 Supplement No ). Aerial photography and ground reconnaissance were used to estimate the extent of these conditions within the treatment units proposed in the LEX project. A separate document in the project file, Lex Soils Unit Table_Appendix A, includes a summary of the extent of this disturbance within each of the proposed treatment units. Project Design Features and Best Management Practices Project Design Features (PDFs) and Best Management Practices (BMPs) are included in this document to reduce ground disturbance during implementation and minimize effects to the soil resource. The analysis of the effects of the proposed activities assumes the implementation of the BMPs and PDCs brought forward into the Environmental Assessment. BMPs referenced for this project are defined in the guide, National Best Management Practices for Water Quality Management on National Forest System Lands (USDA 2012). They provide a general framework of conditions and criteria for minimizing impacts to the soil and aquatic resources during the implementation of the proposed ground disturbing activities. PDCs developed for this project interpret the general language of the BMPs in order to address site specific conditions and further refine criteria for minimizing impacts to the soil resource. 10

11 Best Management Practices (BMPs) adapted from the National Best Management Practices for Water Quality Management of National Forest System Lands Volume 1 (USDA Forest Service 2012) will be implemented as appropriate and are incorporated by reference. Specificallyapplicable BMPs are: Fire-2. Use of Prescribed Fire (p. 54) -2. Location and Design (p. 107) -3. Construction and Reconstruction (p. 110) -4. Operations and Maintenance (p. 111) -5. orary s (p. 114) -6. Storage and Decommissioning (p. 115) -8. Snow Removal and Storage (p. 120) -10. Equipment Refueling and Servicing (p. 123) Veg-2. Erosion Prevention and Control (p. 131) Veg-3. Aquatic Management Zones (p. 132) Veg-4. Ground-Based Skidding and Yarding Operations (p. 134) Veg-6. Landings (p. 136) Veg-7. Winter Logging (p. 137) Veg-8. Mechanical Site Treatment (p. 139) BMPs are standard conservation practices that have proven effective in protecting soil and water resource values during land management activities. They are considered standard operating procedures and apply to all activities. They are assumed to be readily implementable and have a high probability of success when correctly implemented. While these are considered standard operating procedures on all projects occurring on National Forest lands, local variations of many of these have evolved to adapt to specific ground conditions, Regional guidance, and LRMP direction. Where a site-specific design based on a documented BMP is needed, it is listed in the Project Design Features section below. PDFs that address specific sensitive soil concerns in the Lex project area are summarized in Table_3. Primary concerns include proposed machine operations on steep slopes of cinder buttes, in cold air basins with low amounts of organic litter and duff, and in areas where the extent of detrimental soil disturbance is already moderate to high (i.e. >10% of an activity area). 11

12 Table_3. Project Design Features to Avoid or Minimize the Extent of Detrimental Soil on Sensitive Soils or Highly Disturbed Sites Concern High Existing Detrimental soil conditions and All Sensitive Soils Sensitive Soils: steep slopes (>30%) Sensitive Soils: shallow soils on forested lavas Sensitive Soils: cold air basins PDF Overstory treatments Restrict operations to winter only if feasible Retain as leave patches dense stands on inoperable ground (i.e., too rocky or steep) Understory treatments Avoid post-harvest mechanical operations; conduct by hand as is practicable or combine with fuels treatment For young stand management, limit equipment travel and utilize machines with long boom reach; designate and maximize distance between primary travel routes Fuels Treatments Prohibit heavy equipment operations off of existing primary skid trails Maintain effective ground cover and organics, retain >50% of litter/duff depth wherever it exists Retain as much existing large CWD as is practical where it exists Overstory Treatments Avoid operating late in the dry season Minimize sideslope movements by heavy equipment Require a parallel skid trail network running with the slope when practicable Operate forwarding or yarding equipment on a slash bed of sufficient depth to prevent tire or track ruts in mineral soil >6 Operate over sufficient frozen ground and/or snow to prevent the displacement of surface organics and mineral soil horizons Hand fell trees across slope Overstory Treatments Minimize new landings and temporary roads as is feasible; locate new landings on existing roadways Handfell material where machine traffic is limited Avoid and protect outcrop areas All Activities Minimize disturbance and removal of litter and duff; retain existing patches of this material where practicable 12

13 Resource Protection Measures listed in the following section are included to avoid or minimize detrimental soil disturbance and help activities being proposed in the LEX project meet the Deschutes LRMP Standards & Guidelines for the soil resource. Unit-specific listings are included for each measure. Resource Protection Measures for All Action Alternatives s and Skidding Network 1. Minimize the erosive effects of concentrated water through the proper design and construction of temporary roads. Place temporary roads to avoid or minimize cut and fill construction. (LRMP SL-1 & SL-3; BMP -5.) Anticipated Effectiveness: Highly effective. orary roads are lowstandard roads that allow short-term access for timber removal or other stand treatments. Properly designed and maintained drainage features prevent erosion and transport of sediments from the road prism itself and mitigate the potential for off-site impacts from concentrated flow and sediment transport. 2. Ensure that water control structures (water bars or slash surfacing, as approved by the Sale Administrator) are installed at sufficient intervals and maintained on skid trails and temporary roads that have gradients of 10 percent or more; Ensure erosion control structures are stabilized and working effectively. (LRMP SL-1; BMP Veg-4.) Anticipated Effectiveness: Highly effective. Overland flow on skid trails can occur even on the coarse-textured highly-porous pumiceous soils when they are compacted and barren of organic cover. Properly designed and maintained drainage features prevent erosion and transport of sediments from the trail prism itself and mitigate the potential for offsite impacts from concentrated flow and sediment transport. 3. Conduct regular preventive road maintenance on all haul routes to avoid deterioration of the road surface and minimize the effects of erosion and sedimentation. Required post-haul maintenance and stormproofing/winterizing should be accomplished as soon as possible after haul has been completed on each road segment (BMP -4.). orary roads proposed to access Units 2, 9, 11, 12, 16, 55, 59, 60, 61, 75, 81, 83, 84, 85, 91, 99, 100, 102, 103, 104, 110, 117, 118, 128, 139, 140, 143, 151, 166, 167, 168, 186, 201, 204, 205, 210, 211, 236, 240, 252, 253, 276, 281, 290, 294, 295, 298, 299.1, 300, 301, 302, 303.1, 309, 313, 325, 327 and 339. All harvest units All harvest units 13

14 Anticipated Effectiveness: Moderately effective. Success is driven by whether maintenance is kept current and relies on contract administrator oversight. Much road damage results from high-intensity late summer thunderstorms, and completing post-haul/winterizing work as soon as possible instead of waiting until the end of normal operating season helps guard against damage from these events. 4. Avoid skidding in the bottoms of draws, swales, drainageways, or ephemeral channels. Cross perpendicular to the feature, if required (crossings will be approved by the Sale Administrator). If draws, swales, or drainageways are found in units not listed here, they will be treated the same (LRMP SL-1, SL-3, & SL-6; BMP Veg-3.). Anticipated Effectiveness: Highly Effective. Low-lying landscape areas are natural water collection points and recharge areas. Avoiding drainage features with heavy equipment prevents compaction that can limit infiltration and result in standing water or concentrated flow, which can result in surface soil erosion and decrease the amount of plant-available water in soil profile. Prescribed Burn Operations 5. Protect Soils and Water during prescribed burn operations comply with all applicable LRMP standards and guidelines and Best Management Practices in burn plans, which shall be completed before the initiation of prescribed fire treatments in planned activity areas. Include soil moisture guidelines to minimize the risk of intense fire and adverse impacts to soil and water resources from prescribed burning. (LRMP SL-1 & SL-3; BMP Fire-2.). Anticipated Effectiveness: Highly effective. Post-burn monitoring on the Deschutes National Forest has shown that prescribed burn operations very rarely result in detrimental soil conditions from heating/burning (only where logs or stumps are consumed). 6. Particularly on slopes greater than 20%, plan ignition patterns and manage fire intensity to limit intense upslope heating and avoid full litter consumption. (LRMP SL-1, SL-3, & SL-6, BMP Fire-2). Anticipated Effectiveness: Moderately effective. When fire fronts move upslope, rising heat ahead of the fire front dries and cures fuels (including surface soil organic matter), making it more combustible. Greater consumption of surface organics is expected on steeper slopes. Closely-spaced ignition patterns may result in lower intensity and less consumption, though behavior on the ground is difficult to predict and will be greatly affected by atmospheric conditions and fuel and soil moistures. All harvest units. All prescribed burn units All prescribed burn units 14

15 7. Restore machine and hand constructed fire line by redistributing displaced topsoil and unburned woody debris over the disturbed surface. Anticipated Effectiveness: Highly effective. The replacement of displaced topsoil and organic matter to areas where mineral soil has been exposed creates conditions conducive to water retention and microbial activity on site. Retaining Coarse Woody Debris/Down Wood 8. Within all units, where available, retain a minimum standard of 120 linear feet of logs per acre (all decay classes) at least 16 inches in diameter at the small end and at least 16 feet long (a minimum of three cull logs and an additional three in advanced stages of decomposition). Leave more where doing so does not present an excessive fuel hazard. Where 16-inch logs are not present within the unit, the largest available logs should be targeted for retention. Down woody material already on the ground should be retained and protected to the greatest extent possible during all activities (LRMP SL-1 & SL-6). Anticipated Effectiveness: Moderately to highly effective. This design feature, developed in coordination with wildlife specialists, meets standards set forth in the Northwest Forest Plan for wildlife habitat and also meets soils objectives set forth in Graham et al. (1994) and Brown et al. (2003) for both ponderosa pine and mixed conifer sites. Appropriate implementation will depend on the interpretation of equipment operators, with close oversight by the contract administrator. 9. Retain all downed wood greater than 20 inches in diameter at large end in its existing location (i.e. do not pile). During prescribed burn operations, use preventative measures (i.e. placing a line around) and/or light in a manner (i.e. back-burning from the log) to prevent the burning and consumption of snags and logs greater than 20 inches in diameter at the large end. This applies to all decay classes. Also avoid direct lighting of stumps and logs greater than 12 inches in diameter. Coordinate with the project wildlife biologist when burning. (LRMP SL-1, Regional Soil Quality Guidelines). Anticipated Effectiveness: Moderately effective. This design feature was developed in coordination with the wildlife biologist to address soils objectives for long-term nutrient cycling, microbiotic habitat, and effective ground cover, in addition to wildlife objectives. During prescribed burn operations, lighting crews generally avoid directlighting large wood and stumps. However, burn and creep patterns will vary within each unit depending on wind speed and direction, fuel moistures, topography, etc., and some wood will still be consumed. All proposed activity areas All prescribed burn units 15

16 Maintaining Duff Layer 10. Strive to maintain fine organic matter less than 3-inches in diameter (commonly referred to as the duff layer) over at least 65 percent of an activity area following both harvest and post-harvest operations. Adjust minimum amounts to reflect vegetative capabilities if the potential natural plant community on site is not capable of producing fine organic matter over 65 percent of the area (LRMP SL-1 & SL-6; Regional Soil Quality Guidelines; BMP Fire-2.). Anticipated Effectiveness: Highly effective. When skidding patterns are appropriately constrained and off-trail travel adheres to project design requirements, duff retention goals are easily achieved. Monitoring of prescribed burns on the Deschutes National Forest has shown that adequate duff is retained post-burn. Minimizing the extent of new soil disturbance from mechanical treatments 11. Use old landings and skidding networks whenever possible (except where current resource concerns dictate otherwise). All locations for pre-existing or new yarding and transportation s to be used for current entry must be approved by the Sale Administrator prior to operations (includes all skid trails, landings, and temporary roads) (LRMP SL-1 & SL-3; BMP Veg-4. And BMP Veg-6.). Anticipated Effectiveness: Highly effective. Reusing existing networks helps keep detrimental soil disturbances below acceptable thresholds specified in Regional and LRMP guidance. Where resource concerns warrant relocating skidding networks (e.g., skid trails in swale bottoms, impacting wetlands, or running through archaeological sites), the Sale Administrator will help identify suitable locations that minimize resource impacts. 12. Maintain spacing of 100 to 150 feet for all primary (main) skid trails created for conventional feller/buncher/grapple skidder operations, except where converging at landings, to minimize soil impacts. Closer spacing due to complex terrain must be approved in advance by the Sale Administrator. For cut-to-length harvest s, spacing of primary forwarder trails should be at least 65 feet, except where terrain limitations dictate otherwise. To the extent possible, slash mats should be deposited over primary forwarder trails during cutting operations. Main skid trails spaced an average of 100 apart limit soil impacts to 11% of the unit area. For activity areas larger than 40 acres that can accommodate wider spacing, it is recommended that distance between main skid trails be increased to average 150 to reduce the amount of detrimentally disturbed soil to 7% of the unit area (Froelich, Aulerich and Curtis, 1981) (LRMP SL-1 & SL-3, BMP Veg-4.). All proposed activity areas All harvest units All harvest units. 16

17 Anticipated Effectiveness: Highly effective (flat, non-complex topography) to moderately effective (sloping, rocky, or complex topography). Layout is straightforward where there are minimal landscape/topographical constraints or resource avoidance areas that limit where skid trails can be placed. Where rock outcrops, wet soils, avoidance areas, steep slopes, unit shape, or orientation of existing skidding network necessitates closer spacing, rehabilitation/ of excessive detrimental soil impacts may be necessary. 13. Grapple skidders will be restricted to primary skid trails, landings, and approved roads at all times. Harvesting machinery will be permitted to leave primary skid trails at 30-foot intervals to cut and accumulate material, making no more than two passes over any piece of ground. Harvesting machinery should make only linear passes out and back, constraining pivots and turns to primary skid trails where feasible (LRMP SL-1 & SL-3, BMP Veg-4.). Anticipated Effectiveness: Highly to Moderately Effective. Constraining rubber-tired skidders to primary skid trails limits the amount detrimental compaction resulting from multiple passes. Harvester travel off of primary skid trails should not result in detrimental compaction. Research has shown that at it takes three to five passes to result in detrimental soil compaction (Froehlich and McNabb, 1983) and this has been confirmed locally through Forest soil condition monitoring (Craigg, 2000; Hash, 2011) (highly effective). Limiting pivots and turns away from primary skid trails greatly decreases the amount of detrimental displacement, though site-specific stand conditions may require limited off-trail maneuvering (moderately effective). 14. Cease operations during periods of high soil moisture or if frozen ground or snow begins to thaw and damage to soil occurs. Some watch-out situations include: machine break-through begins to occur; equipment tracks sink deeply (half the width of the track) below the soil surface with one or two passes; ruts greater than six inches deep form; mid-day temperatures are forecast to rise above freezing; surface melt occurs over still-frozen subsurface (LRMP SL-1 & SL-3; BMP Veg-4. & Veg-7.). Anticipated Effectiveness: Moderately Effective. Limiting rutting and puddling damage during wet conditions requires mindful oversight from Sale Administrator. Operations generally cease only after thresholds are crossed and damage occurs. All harvest units All proposed activity areas 17

18 15. Machine piling treatments to reduce fuel loadings shall be implemented to minimize soil disturbance as follows (LRMP SL-1 and SL-3; BMP Veg-8.): Restrict grapple piling machinery to designated routes used for harvest operations where fuel loads are moderate or low. Where fuel loads are high, limit off-trail machine travel to no more than two passes on any piece of ground. Where feasible, turns and pivots should be constrained to primary skid trails to limit soil displacement. Operators shall plan travel paths to make full use of the machine s capability (e.g., using full boom reach of machine) to limit ground disturbance and minimize number of off-trail passes needed to achieve treatment objectives. Where feasible, pile fuels (both hand and machine piles) on facilities (i.e. skid trails and landings) in order to minimize additional detrimental soil impacts from burning (LRMP SL-1 & SL-3; BMP Veg-8.). Anticipated Effectiveness: Moderately effective. In many cases, breaking up fuel continuity by piling material that can be reached from skid trails will achieve fuels objectives while limiting soils impacts. In some instances, machines may need to leave skid trails to achieve piling objectives. Limiting off-trail passes will limit the amount of detrimental compaction incurred, but may still cause some displacement damage. Piling on existing disturbances will limit the amount of additional detrimental soil conditions incurred as a result of burning, though fuel loadings and logistics will often require piles scattered within the unit. 16. Mastication or other mechanized understory treatments to reduce brush and fuel loadings shall be implemented to minimize soil disturbance as follows (LRMP SL-1 and SL-3; BMP Veg-8.): All proposed activity areas All proposed activity areas When using a boom-mounted implement, operator shall plan off-trail travel paths to make full use of the machine s capability (e.g., using the full boom reach of the machine) to limit ground disturbance and minimize the number of off-trail passes needed to achieve treatment objectives. When using a machine with a front-mounted fixed masticating head, work in long, linear swaths to the extent practicable to avoid unnecessary pivoting and turning, which results in soil displacement damage. Operator should not allow masticating heads or other implements to make contact with the soil surface, which can result in detrimental churning and mixing of the soil. 18

19 Machines shall make no more than two passes over any piece of ground (when not on primary skid trails or landings). Detrimental soil impacts resulting from post-harvest understory treatments shall be isolated and infrequent (less than 5% of the unit area). Detrimental impacts include total removal of surface organics and topsoil, churning/mixing of topsoil with subsoil, rutting greater than six inches deep, and heavy compaction. Unless otherwise specified to meet wildlife or other resource objectives, limit treatment to 80% of the unit area, leaving 20% in both untreated islands of 0.5 to 2 acres in size and in isolated pockets of smaller size equally distributed through the unit. Anticipated Effectiveness: Moderately effective. Mastication and other understory treatments result in varying degrees of soil disturbance depending on the type of machinery used. Fixed-head machines that require machinery to travel over every piece of ground to be treated result in more soil disturbance, while boom-mounted machines can take advantage the machine s reach to directly disturb less ground. Successful implementation requires close oversight by the Sale Administrator to make sure fuels reduction objectives are met while minimizing soil disturbance. 17. For slopes greater than 30 percent falling within activity units (LRMP SL-1, SL-3 & SL-5; BMP Veg-4.): Use advanced s where treatment is planned for slopes greater than 30%. Advanced s may include a variety of techniques including, but not limited to, cable yarding or use of harvester-forwarder s where adequate protection against soil compaction and displacement can be demonstrated. Small inclusions of slopes greater than 30% within ground-based harvest units will be prioritized for leave areas within units. Exceptions for areas that make up less than 10 percent of an activity area would be subject to Forest Service approval. Machine traffic off of designated skid trails for harvest or yarding is prohibited. Directional hand falling of trees on slopes greater than 30% that cannot be reached by shears from designated skid trails is permitted. Leading end suspension is required when cabling or skidding material. Any temporary road development on slopes greater than 30% will require Forest Engineer input and approval. All proposed activity areas on buttes. Specifically, Units 236, 252, 266, 295, 309, 312, 313, 321, and

20 Skid trails or yarding corridors on slopes greater than 30% used by the purchaser shall be reclaimed by applying appropriate erosion control measures such as the placement of slash in conjunction with, or in place of, waterbars for rehabilitation. Anticipated Effectiveness: Highly effective. Limiting ground-based equipment on slopes over 30% protects soils with the greatest erosion and displacement hazard ratings. 18. Construct fireline to the minimum width and standard necessary to contain prescribed fire and meet overall objectives. Consider alternatives to ground-disturbing fireline, including wet line, rock outcrops, roads, or other features. Reclaim all machine-built fire lines by redistributing displaced topsoil and unburned woody debris over the disturbed surface (LRMP SL-1 & SL-3; BMP Fire-2.). Anticipated Effectiveness: Highly effective. Replacing topsoil and reestablishing surface cover on machine-built fireline will minimize erosion potential and discourage vehicle or foot travel. 19. Apply treatments (e.g. subsoiling, surface cover placement) to primary facilities where needed to meet LRMP standards or reduce overall impacts. Units with prior entries and elevated existing detrimental conditions are likely to need treatments to meet LRMP standards for soil productivity (LRMP SL-1, SL-3, SL-4, & SL- 6; BMP Veg-4. and Veg-6.). Anticipated Effectiveness: Moderately to highly effective. Subsoiling is an effective treatment for reducing compaction levels below detrimental thresholds on pumice and ash soils. Placement of fine slash or other organic materials may need to accompany subsoiling to establish effective groundcover, reduce surface crusting, maintain tilth, and moderate soil microclimate for successful natural revegetation. 20. Rehabilitate all temporary roads created for the current entry. This may include masking/obliterating entrances, subsoiling, utilizing excavator bucket teeth to loosen compacted soils, recontouring cuts and fills, hydrologically stabilizing, seeding, and/or placing fine slash or other organic materials over treated surfaces to establish effective ground cover protection where available. Subsoiling of temporary roads may occur as a post-sale area improvement activity where conditions are appropriate (LRMP SL-1, SL-3, & SL-4; BMP -5.). Anticipated Effectiveness: Moderately effective. orary roads are considered to be a short-term commitment of soils resources, and must be rehabilitated after use. Reestablishing natural contours, decompacting surfaces, and reestablishing surface cover will decrease erosion risk and encourage rapid natural revegetation. Effective closure/obliteration is essential to discourage vehicle use and repeated disturbance. All prescribed burn units Harvest activity units with prior entries and elevated existing detrimental conditions see Table Appendix A for a list of units by Alternative requiring treatments. All harvest units. orary roads proposed to access Units 2, 9, 11, 12, 16, 55, 59, 60, 61, 75, 81, 83, 84, 85, 91, 99, 100, 102, 103, 104, 110, 117, 118, 128, 139, 140, 143, 151, 166, 167, 168, 186, 201, 204, 205, 210, 211, 236, 240, 252, 253, 276, 281, 20

21 To protect sensitive soils 290, 294, 295, 298, 299.1, 300, 301, 302, 303.1, 309, 313, 325, 327 and Use some or all of the following avoidance/minimization measures to protect sensitive frost pocket soil types (mapped as SRI 15 in this project area) as feasible (LRMP SL-1, SL-3, and SL-5): Avoid placing landings in these areas to the extent practicable. Avoid routing temporary roads through these areas. If temporary roads are necessary, they should be decompacted with a minimum of 50% organic surface cover (e.g. fine slash) applied, where available onsite, after use. Prioritize for leave areas Minimize topsoil and organic layer displacement within units by limiting machine pivots and turns to primary skid trail and landings. Anticipated Effectiveness: Moderately effective. Because frost pocket soil types have low resistance to and resilience from impacts (particularly displacement and organic cover disruption), it is advisable to limit large-scale disturbances like landings and temp roads. However, where total avoidance isn t feasible, reclamation through decompaction and retention/application of surface organics improves soil recovery by moderating temperature flux. 22. Use some or all of the following avoidance/minimization measures to protect cinder soil types with a high displacement risk (mapped as SRI 82 in this project area) as feasible (LRMP SL-1, SL-3, and SL-5): Avoid side-hill machine travel on slopes greater than 15%. Orient skid trails parallel to the fall line where feasible. Repair areas where a substantial amount (100 square feet or greater) of surface soils are displaced, exposing the subsurface cinders. Displaced Mazama ash surface soil should be pulled back in and smoothed over displaced areas. Use slash surfacing on skid trails or harvester trails if cinder exposure is routinely occurring during harvest. Use slash surfacing in lieu of water bars for erosion control, as approved and directed by the Sale Administrator. Soil type 15 mapped in Units 21, 21.1, 21.2, 103, 166, 203, and 215. Cinder soil types mapped in Units 236, 252, 266, 295, 309, 312, 313, 321, and Anticipated Effectiveness: Moderately effective. These soil types generally have cinder at depth that can be exposed when Mazama surface soils are displaced. Because underlying cinders are low in 21

22 nutrients, very droughty, and have poor thermal properties, it is advisable to avoid surface displacement when possible and to repair large exposures resulting from machine damage. Using slash surfacing for erosion control prevents the unintended exposure of cinders when excavating water bars. Slash surfacing has proven to be effective for minimizing surface erosion on Mazama ash soil types. Effects Direct, indirect and cumulative effects analyzed for the soil resource include those that can detrimentally impact the physical, chemical and biological properties that influence the function and productivity of the resource. This analysis describes the extent and manner in which the proposed management activities could affect the disturbance types described in the Region 6 supplement to the 2520 Forest Service Manual and whether these disturbances would be within allowable levels to maintain soil productivity within an individual activity area 1 (Deschutes LRMP and R-6 Supplement No ). The following disturbance types are discussed in this analysis: COMPACTION: Detrimental compaction is defined as a 20% increase in bulk density or soil strength for ashy soils. Three to five passes by a crawler tractor or rubber-tired skidder over the same piece of ground commonly produces this effect. DISPLACEMENT: Detrimental displacement is defined as the removal of more than 50% of the A horizon from an area greater than 100 square feet, which is at least 5 feet in width. BURN DAMAGE: Detrimental burn damage occurs when the mineral soil surface has been significantly changed in color, oxidized to a reddish color, and the next one-half inch blackened from organic matter charring by heat conducted through the top layer. PUDDLING: Detrimental puddling occurs when the depth of ruts or imprints is six inches or more. Soil deformation and loss of structure is observable and bulk density is usually increased. 1 Activity Area is described as the total area of ground impacting activity, and is a feasible unit for sampling and evaluating. Some examples are: a sale contract unit, pasture, allotment, meadow, riparian reach, burned area (FSM ) 22

23 EROSION: Detrimental erosion occurs when there is visual evidence of surface loss in areas greater than 100 square feet, rills or gullies and/or water quality degradation from sediment or nutrient enrichment 2. Alternative 1 None of the proposed actions described under the action alternatives would be implemented under Alternative 1. Existing levels of soil disturbance would not be affected by ground disturbing activities and would remain the same as those described in the existing condition section of this report and the unit tables in Appendix A. The risk of high intensity wildfire is greatest under this alternative and could result in the largest extent of exposed mineral soil and detrimental burn damage in the short term compared to the action alternatives. The untreated stands within the project area would remain susceptible to high intensity wildfires due to the dense canopies and elevated surface loading of fuels in the Ponderosa and Mixed Conifer Forest types compared to historic ranges. However, although these conditions provide the greatest risk for incurring detrimental burn damage to the soil resource if a wildfire were to occur, even this type of event in high density stands has resulted in less than 5% detrimental burn damage to the soil resource within recent fires in comparable stand types across the Forest (i.e. the B&B Complex in 2004 and the Pole Creek Fire in 2012). The potential for surface erosion from wind and water would be elevated in the near term following a fire event, although the nutritive availability from organic fuel consumption/cycling is likely to offset any reduction of productivity from the direct loss of mineral soil on site. Alternatives 2, 3 and 4: Direct, indirect and cumulative effects to the soil resource are all analyzed at the activity area or unit scale. Although the spatial extent of the proposed commercial harvest treatments and fuels treatments varies slightly between the action alternatives (Alternative 2 proposes to treat 5,465 acres with ground based commercial harvest treatments while Alternative 3 would treat 6,011 acres and Alternative 4 would treat 5,101 acres), the types of treatments proposed within activity areas are similar under each of the alternatives. As a result, the direct, indirect and cumulative effects of the proposed activities analyzed at the unit scale would be similar between alternatives and the effects of the proposed actions displayed in Chapter 2 of the DEIS on the soil resource are analyzed as common between the three action alternatives. 2 The volcanic ash soils along the east slopes of the Cascade Mountains have several properties which can make erosion hazard assessment difficult. These soils have rapid infiltration rates and permeability when profiles are uncompacted and organic surface cover is present but their weak granular to singular grain structure in the profile makes them susceptible to surface erosion when water is channeled on the soil surface from compacted skidroads, waterbar outlets, and road drainage structures (Ash Soil Guidelines for OR/WA 1985). 23