EFFECTS OF TIMBER HARVEST ON THE SOIL RESOURCE ON THE DIXIE NF Developed by Jim Bayer, 1996 Updated by Jaros, June 2006

Transcription

1 EFFECTS OF TIMBER HARVEST ON THE SOIL RESOURCE ON THE DIXIE NF Developed by Jim Bayer, 1996 Updated by Jaros, June 2006 This paper is being written to discuss the impacts timber harvest may have on the soil resource. Additionally, it discusses what the Forest Service, and in particular what the Dixie National Forest does, to insure that timber harvest does not adversely impact long term soil productivity. WHAT CONSTITUTES DAMAGE TO LONG TERM SOIL PRODUCTIVITY? The Forest Service Intermountain Region has developed the R-4 Supplement to FSH (1/21/2003) which establishes soil quality standards and guidelines and defines detrimental changes in soil qualities that can be created due to management. The following information is from the R-4 Supplement. 1. Soil Quality Standard. Soil resource management must be consistent with the Forest Service goal of maintaining or improving long-term soil productivity (NFMA) and soil hydrologic function. 2. Soil Quality Guidelines. Soil quality guidelines provide for the maintenance of soil properties that affect soil productivity and hydrologic function. Management activities can damage soils by compaction, puddling, displacement, severe burning, organic matter loss, accelerated surface erosion, or mass movement. Soil damage is detrimental when it adversely affects hydrologic function or results in long-term site productivity losses. Soil Quality Guidelines set the limits of disturbance, or thresholds, beyond which there will be long-term losses in inherent soil productivity or hydrologic function. Detectable losses of soil productivity and soil hydrologic function will occur if disturbances exceed the guidelines. The guidelines represent the upper limit of allowable disturbances. The management goal should be to cause as little disturbance as possible. The effects of management practices on compaction, puddling, organic matter loss, erosion, and displacement may be cumulative over time. Existing, predicted, and cumulative levels of soil disturbance are used together to determine that guidelines are being met. Guidelines are assessed by Activity Area, which is specifically described for each management activity. Soil properties that are easy to quantify may be used as surrogates to determine effects on soil fertility and structure. These properties include organic matter (both within and on the soil), soil porosity, and soil strength. These soil properties are maintained by the application of guidelines for soil displacement, soil compaction, soil puddling, severely burned soils, ground cover, and aboveground organic matter. Ground cover is a guideline because it protects soil from accelerated erosion. Displacement of humus-rich surface soil is a substitute for soil organic matter content. The guidelines used as indicators of soil quality and as measures of conformance to soil quality standards are given below. EFFECTS OF TIMBER HARVEST ON THE SOIL RESOURCE ON THE DIXIE NF Updated Jaros 2006 Page 1 of 73

2 a. Detrimental Soil Disturbance. No more than 15 percent of an activity area should have detrimentally disturbed soil after the completion of all management activities. In other words, at least 85 percent of an activity area should be in a nondetrimentally disturbed condition. Some examples of management options limiting the effects of soil disturbance and mitigation measures are listed in exhibit 03. (1) Detrimental Soil Displacement. Detrimental soil displacement includes areas where 1 meter by 1 meter or larger exhibits detrimentally displaced soil as described below: (a) The loss of either 5 cm or ½ of humus enriched top soil (A horizon), whichever is less, or (b) The exceeding of the soil loss tolerance value for the specific soil type. (2) Detrimental Soil Compaction. Soil Compaction is generally evaluated from 5 to 30 centimeters below the mineral soil surface. Specific depths for measurement are dependent upon soil type and management activities. Detrimental Soil Compaction is increased soil density (weight per unit volume) and strength that restricts root growth, reduces soil aeration and inhibits water movement. Measurements of potential detrimental soil compaction may be qualitative or quantitative. The following table provides a set of indicators that can be used to measure detrimental compaction. The methods to measure the indicator, measurement standard, and reliability of the indicator are included in the table. Any of the indicators in Table Compaction 1 or other appropriate indicators identified for the activity area may be used to determine detrimental soil compaction. Document reasons for selecting an indicator(s) for measuring detrimental soil compaction. EFFECTS OF TIMBER HARVEST ON THE SOIL RESOURCE ON THE DIXIE NF Updated Jaros 2006 Page 2 of 73

3 2.2 Exhibit 01 Table Compaction 1. Indicators and Methods for Measuring Detrimental Soil Compaction Indicator Measure Measurement Standard Reliability Soil structure change Soil strength Soil strength Bulk density Calibrated ocular examination of soil layers Calibrated shovel penetration resistance Calibrated penetrometer readings Soil samples and lab analysis sampling methods vary by soil characteristics Bulk density Soil samples sampling methods vary by soil characteristics Evidence of change to platy structure or lack of structure (massive) from granular, blocky or sub-angular blocky structure Shovel penetration is difficult relative to pre-disturbance levels A reading increase over predisturbance levels that correlates to the measurement standards for soil structure change, shovel penetration resistance and or bulk density increase. This value must be adjusted for soil moisture conditions at the time of sampling. Significant change in the distribution of Bulk Density of the activity area soils from undisturbed or similar undisturbed soil types. Threshold values by soil texture are used to determine Detrimental soil disturbance. Threshold values are those where significant root limiting, and infiltration reduction conditions exists. Threshold values are shown in Table Compaction 2 Moderate can be described but not quantified - observations should be calibrated with bulk density readings Moderate difficult to quantify except indirectly by calibration with bulk density and or penetrometer readings; can be combined easily with ocular exam for induced platy structure High consistent quantitative measurements in relatively rock free soils High consistent quantitative measurements; can also be correlated with soil strength High consistent quantitative measurements; can also be correlated with soil strength 2.2 Exhibit 02 Table Compaction 2. Threshold Bulk Density Values by Texture (USDA NRCS, Soil Quality Information, Compaction 1996) Threshold Root Restricting Bulk Soil Texture Density (g/cc) Coarse, medium, and fine sand and loamy sands other than loamy very fine sand 1.80 Very fine sand, loamy very fine sand 1.77 Sandy loams 1.75 Loam, sandy clay loam 1.70 Clay loam 1.65 Sandy clay 1.60 Silt, silt loam 1.55 Silty clay loam 1.50 Silty clay 1.45 Clay 1.40 EFFECTS OF TIMBER HARVEST ON THE SOIL RESOURCE ON THE DIXIE NF Updated Jaros 2006 Page 3 of 73

4 (3) Detrimental Soil Puddling. Detrimental Puddling is generally evaluated at the mineral soil surface. Visual indicators of detrimental puddling include clearly identifiable ruts with berms in mineral soil, or in an Oa horizon of an organic soil. Detrimental puddling may occur in conjunction with detrimental compaction. The guidelines for soil compaction (item (2) above) are to be used when this occurs. Detrimentally puddled soils are not always detrimentally compacted. Infiltration and permeability are affected by detrimental soil puddling. Puddling can also alter local groundwater hydrology and wetland function, and provide conduits for runoff. Forests are encouraged to develop infiltration and/or permeability guidelines that relate to detrimental puddling. (4) Severely Burned Soil (sec. 2.05). The severely burned soil guideline applies to prescribed fire and natural fires that are managed for resource benefits. Severely burned soils are identified by ratings of fire severity and the effects to the soil. A severely burned soil is generally soil that is within a High Fire Severity burn as defined by the Forest Service Burned Area Emergency Rehabilitation Program (FSH ) and Debano et. Al Develop a high fire severity rating for each fire activity area as local soils and vegetation types respond differently to the effects of fire. An example of a high fire severity rating is provided as exhibit 04. Soil humus losses, structural changes, hydrophobic characteristics and sterilization are potential effects of severely burned soil. b. Effective Ground Cover. The minimum effective ground cover, following the cessation of disturbance in an activity area, should be sufficient to prevent detrimental erosion. Detrimental erosion includes erosion rates that cause longterm productivity losses from an activity area or soil losses that are beyond those acceptable for the activity area. Minimum amounts of ground cover necessary to protect a soil from erosion are a function of soil properties, slope gradient and length, and erosivity (precipitation factor) and must be determined locally. Rock fragments, litter, and canopy might be treated independently, depending on the model utilized to estimate erosion hazard ratings. All Forests and Grasslands should establish local minimum effective ground cover guidelines to assure that detrimental erosion will not occur. c. Above-ground Organic Matter. Some litter or large woody debris may be required to retain nutrients and microorganisms necessary to supply and cycle nutrients needed to maintain site productivity on forest and rangelands. The aboveground organic matter also provides for on-site moisture retention. (1) Litter. Forests and Grasslands must develop local guidelines for litter retention based on factors such as soil and vegetation types. (2) Coarse Woody Debris. The minimum amount of large woody debris required to maintain nutrient and moisture supplies adequate to sustain site productivity EFFECTS OF TIMBER HARVEST ON THE SOIL RESOURCE ON THE DIXIE NF Updated Jaros 2006 Page 4 of 73

5 varies by ecological type. Coarse Woody Debris guidelines apply to ecological types that are capable of producing forested and woodland ecosystems. Guidelines for these minimum amounts are ascertained through research studies or developed by forests based upon local factors such as soil potential and vegetation types. Studies that are available to assist in determining minimum amount of Coarse Woody Debris include A.E. Harvey et al and Russ Graham The previous information defines detrimental changes in soil qualities that may occur due to management, and discusses Regional soil quality standards and guidelines that have been established. To briefly summarize, long term soil productivity and hydrologic function can be adversely impacted if soils are detrimentally disturbed (displaced, compacted, puddled, severely burned) or if there is too little ground cover or above-ground organic matter (litter, large woody debris). The R-4 Supplement sets thresholds for these parameters. It is the responsibility of the Forests to propose timber harvest strategies and appropriate mitigation to ensure that the thresholds are not exceeded. WHAT EFFECT DOES TIMBER HARVEST HAVE ON THE SOIL RESOURCE? Harvest and site preparation methods can damage the physical soil resource and decrease longterm productivity. The major disturbance categories are soil compaction, surface disturbance, effects associated with fire, and soil removal (Childs et al.,1989). SOIL COMPACTION: The effects of soil compaction have been extensively studied, and excellent reviews are available (Greacen and Sands, 1980; Froehlich and McNabb, 1984). Increase in soil bulk density is correlated with changes in other soil properties (e.g., strength, water storage, aeration), and there is little doubt that compaction affects the physical environment enough to decrease productivity (Childs et al., 1989). Reduction in root growth, height, and timber volume have been observed (Froehlich and McNabb, 1984) and may result from the compaction produced by as little as one pass of a logging vehicle over a site (Wronski, 1984). The percentage decrease in tree height has been linearly correlated to percentage increase in bulk density (Froehlich and McNabb, 1984). Productivity loss has been documented on whole sites (Wert and Thomas, 1981) as well as for individual trees (Froehlich, 1979; Helms and Hipkin, 1986). Decreases in microbial populations have been observed in compacted soils for up to 5 years (Smeltzer et al.,1986). In general, however, the effects directly observed in field studies result from environmental degradation due to both compaction and disturbance or removal of surface soil. The specific effects of compaction alone have not been isolated (Childs et al., 1989). A considerable body of literature shows that bulk-density increase due to logging is long lived. Froehlich and McNabb (1984) summarized data that show compaction effects persisting for as long as 40 years. Wert and Thomas (1981) observed decreases in height and volume growth after as long as 32 years. SOIL SURFACE DISTURBANCE EFFECTS OF TIMBER HARVEST ON THE SOIL RESOURCE ON THE DIXIE NF Updated Jaros 2006 Page 5 of 73

6 Mixing and short-distance displacement of topsoil from a site can decrease productivity. Although the areal extent of bare surface exposed by logging is likely to be less than 30% of a given site (Rice et al., 1972; Miller and Sirois, 1986), the impact can be severe. Physical effects of surface disturbance include destruction of soil structure and increased erosion potential (Childs et al., 1989). Soil structure can be altered in two ways. First, during logging in wet soils, surface structure can be obliterated by the kneading action of machinery and logs (Froehlich and McNabb, 1984), producing a damaged surface without deep compaction. The surface loses structural features of good pore-size distribution, continuity among soil pores, and aggregation of individual particles into larger groups; the soil is said to be "puddled". Removal of surface slash and litter also decreases the resistance of the soil to puddling or compaction damage caused by tractor logging (Jakobsen and Moore, 1981); the resulting surface is sealed to water and gas movement and often dries to a hard, dispersed layer. Second, the disturbed soil surface may cause the common biological agents of structural development (mycorrhizae, fungi, microbes, roots) to be less effective (Morris and Pritchett, 1983). The exact nature of this effect is unknown but results from changes in soil microclimate as well as interruption of nutrient cycling by removal or damage to plant roots. Once bare soil is exposed, decreased infiltration rates of disturbed surfaces generally result in increased erosion (Johnson and Beschta, 1980; Wronski, 1984; Beasley et al., 1986) for up to 6 years. Road construction/reconstruction is a major soil disturbance activity associated with most timber harvest operations. Roaded areas, by and large, are the greatest source of surface eroded sediment from managed forests, especially during the first year following road construction (Sidle,?). EFFECTS OF FIRE Fire directly affects the soil physical resource by consuming soil organic matter (Wells et al., 1979), altering soil clay or organic colloids (Tarrant, 1956; Ralston and Hatchell, 1971), creating hydrophobic (water-repellent) layers (Henderson and Golding, 1983), decreasing infiltration rates (Dyrness, 1976), and increasing solar energy absorbed by the blackened soil surface (Holbo and Childs, 1987). The worst fire effects documented have come from studies of machine piling and burning for site preparation (Tarrant, 1956; Wells et al., 1979). However, none of the above-mentioned direct effects is likely to decrease long-term productivity if fire intensities and temperatures are kept low (Childs et al., 1989). Destruction of soil organic matter and alteration of soil colloids are generally observed only after extremely hot fires such as those beneath burning slash piles (Tarrant, 1956). Yet severely burned sites generally cover less than 5% of harvested areas following slash burning (Tarrant, 1956; Wells et al., 1979). Furthermore, fire almost never consumes the entire forest floor, let alone the organic matter in the mineral soil (Pritchett, 1979). Water repellency and increased absorption of solar radiation by the blackened soil surface appear to last only one or two growing seasons. The effects of water repellency are also minimal because the areal extent is commonly patchy (Childs et al., 1989). EFFECTS OF TIMBER HARVEST ON THE SOIL RESOURCE ON THE DIXIE NF Updated Jaros 2006 Page 6 of 73

7 Loss of organic matter allows precipitation to strike directly on the exposed surface of the mineral soil. This can result in disaggregation of surface structure (Wells et al., 1979) increasing soil density and decreasing soil aeration and infiltration. Because these effects occur near the surface, they are probably short lived. There is, however, the potential for significant erosion during this period (Tiedmann et al., 1979). If erosion is severe, productivity may decline because enriched topsoil is lost before revegetation and other natural recovery processes stabilize the site (Childs et al., 1989). Although fire generally causes short-term phenomena, the temporarily harsh environment could delay reforestation. Where a soil is quite fragile (e.g., extremely shallow, with very little native fertility or buffering capacity, on steep or exposed areas susceptible to erosion, in a harsh microclimate), even a short initial delay in reforestation may result in conditions which retard reestablishment of a productive stand (Childs et al., 1989). SOIL REMOVAL Short-term growth appears to be strongly affected when topsoil is removed. Effects are most severe on shallow soils but can be important on deeper soils as well. The primary effect of soil removal is that it decreases organic matter levels and nutrient supply (Klock, 1982). However, the process of removing soil involves use of tractive machines on most of the site, superimposing the added detrimental effects of soil compaction and surface disturbance. Furthermore, where soil is removed during operations such as machine piling and burning, the site may also sustain fire damage. Soil removal is frequently a by-product of site preparation intended to control competing vegetation. Short-term studies of these practices are, therefore, often inconclusive because the damaging effects of soil removal are mitigated by the short-term benefits of vegetation control (Tuttle et al., 1985). There is little question, however, when studies of long-term growth (e.g., Coile and Schumacher, 1953; Glass, 1976) or soil nutrient status (Klock, 1982; Tuttle et al., 1985) are considered: removing topsoil adversely affects long-term site productivity. WHAT DOES THE DIXIE NATIONAL FOREST DO TO ENSURE THAT TIMBER HARVEST DOES NOT ADVERSELY IMPACT LONG TERM SOIL PRODUCTIVITY? As stated earlier, it is the responsibility of the Forests to propose timber harvest strategies and appropriate mitigation to ensure that the thresholds for soil resource protection are not exceeded. On the Dixie National Forest this has been accomplished through direction established in the Dixie National Forest Land Management Plan and through the use of Soil and Water Conservation Practices (Best Management Practices) recommended by soil and water specialists working on NFMA/NEPA Interdisciplinary Teams. DIXIE NF STANDARDS FOR PROTECTION OF LONG TERM SOIL PRODUCTIVITY Based on the previous discussion in this document, the following standards will be used to ensure long-term soil productivity is maintained on the Dixie NF. Much of the information EFFECTS OF TIMBER HARVEST ON THE SOIL RESOURCE ON THE DIXIE NF Updated Jaros 2006 Page 7 of 73

8 that has been presented previously is summarized here again, and in some cases expanded upon, for clarification purposes. Logging activities cause varying degrees of soil disturbance, which may cause a detrimental change in productivity. Detrimental change is defined as a 15% reduction in inherent soil productivity potential (FSH ). Soil Quality Standards (threshold values) are set for soil properties or conditions for determining when the changes become detrimental. The desired future condition (DFC) for logged areas on the Dixie NF is that, following logging or associated prescribed fire, long term soil productivity and soil hydrologic function will be maintained or improved on as many acres as possible, but at least on 85 percent of the activity area. (This means that 85 percent of an activity area must have soils that do not exceed soil erosion or detrimental disturbance thresholds described below). An activity area is defined as a land area impacted by a management activity, excluding specified transportation facilities and dedicated trails (FSH , R4 Supplement, 2003). For timber sales on the Dixie NF, an activity area is defined as the harvest units within the timber sale project boundary, exclusive of roads, primary skid trails and permanent landings. The kinds of potential adverse impacts to the soil resource associated with logging include reduced above ground organic matter, severely burned soil, soil erosion, and soil disturbance (which includes compaction, puddling and soil displacement). ABOVE GROUND ORGANIC MATTER: Research has shown that above ground organic matter (litter and large woody material) are required to maintain long term site productivity. The organic matter is needed to maintain beneficial microbial activity and for nutrient cycling. Timber harvest activities (logging, slash treatment, etc.) can have dramatic effects on the amount of above ground organic matter that is left on site. Recent studies recommend leaving a minimum of 10 to 15 tons per acre of large woody material (>3 inches in diameter) after timber harvesting and other site treatments (Harvey, et al, 1987). These recommendations are presently being refined to make them more specific based on habitat types (Graham, et al, 1994). Until these more specific guidelines are received, the Dixie NF will continue to recommend 10 to 15 tons per acre of large woody material be left on site unless the site is not capable of producing that much material under natural conditions. This recommendation may be modified to ensure that fuel management guidelines are not exceeded. Other constraints, such as visuals in a travel corridor, may cause the organic matter recommendations to be altered in special cases, but in general, and on most sites, the goal will be to maintain 10 to 15 tons per acre of large woody material, fairly evenly distributed over the site. SEVERELY BURNED SOILS: The main effect of burning is loss of organic matter and nutrients. Soil humus losses, structural changes and sterilization are additional effects of burning. Very hot fires such as wild fires which totally consume all above ground vegetation and litter can result in large areas EFFECTS OF TIMBER HARVEST ON THE SOIL RESOURCE ON THE DIXIE NF Updated Jaros 2006 Page 8 of 73

9 of severely burned soils. In timber management activities very hot fires can occur under large slash piles. To ensure that long term site productivity is not adversely impacted during slash treatment activities on the Dixie NF, emphasis will be placed on using slash treatment strategies that do not result in very hot fires (broadcast burning, smaller slash piles, etc.) or slash treatments that do not involve fire. If large slash piles are the chosen treatment method, recommendations will be made to ensure that the total acres affected, added to the acres that receive detrimental soil disturbance, do not exceed the threshold established of maintaining at least 85 percent of an activity area with soils in a satisfactory condition. SOIL EROSION: The policy of the Dixie NF is that no forested areas will be harvested that would result in erosion rates that would exceed the soil loss tolerance threshold (T factor). Such areas are to be classified as unsuitable. (Logged areas are allowed to exceed the T factor temporarily the first year or two following logging, however the T factor will not be exceeded in the long term, i.e. soil erosion will not exceed soil formation in the long term). In addition, no areas will be designated for logging if the erosion from those areas would result in unacceptable damage to downstream values (water quality, fisheries habitat, etc.). These areas would also be classified as unsuitable. For harvested areas on the Dixie NF, the DFC will be that following the cessation of disturbance in an activity area, the minimum ground cover should be sufficient to prevent erosion from exceeding the rates of natural soil formation (soil-loss tolerance). The goal will be to have approximately the same ground cover conditions (combination of litter, vegetation and rock fragments >3/4 inch diameter) after logging that exist on similar unlogged areas. Best Management Practices (BMP's) will be used that provide sufficient soil protection to limit erosion to near natural rates. DETRIMENTAL SOIL DISTURBANCE. No more than 15 percent of an activity area should have detrimentally disturbed soil after the completion of all management activities. In other words, at least 85 percent of an activity area should be in a non-detrimentally disturbed condition. DETRIMENTAL SOIL DISPLACEMENT. Detrimental soil displacement includes areas where 1 meter by 1 meter or larger exhibits detrimentally displaced soil as described below: (a) The loss of either 5 cm or ½ of humus enriched top soil (A horizon), whichever is less, or (b) The exceeding of the soil loss tolerance value for the specific soil type. DETRIMENTAL SOIL COMPACTION. Soil Compaction is generally evaluated from 5 to 30 centimeters below the mineral soil surface. Specific depths for measurement are dependent upon soil type and management activities. Detrimental Soil Compaction is increased soil density (weight per unit volume) and strength that EFFECTS OF TIMBER HARVEST ON THE SOIL RESOURCE ON THE DIXIE NF Updated Jaros 2006 Page 9 of 73

10 restricts root growth, reduces soil aeration and inhibits water movement. Measurements of potential detrimental soil compaction may be qualitative or quantitative. DETRIMENTAL SOIL PUDDLING. Detrimental Puddling is generally evaluated at the mineral soil surface. Visual indicators of detrimental puddling include clearly identifiable ruts with berms in mineral soil, or in an Oa horizon of an organic soil. Detrimental puddling may occur in conjunction with detrimental compaction. The guidelines for soil compaction (item (2) above) are to be used when this occurs. Detrimentally puddled soils are not always detrimentally compacted. Infiltration and permeability are affected by detrimental soil puddling. Puddling can also alter local groundwater hydrology and wetland function, and provide conduits for runoff. Based on a considerable amount of research, reports and studies (including local studies made on the Dixie NF), a number of assumptions have been made regarding effects of logging on soil disturbance of soils on the Dixie NF. 1. The first passes of logging equipment over an area compacts the upper few inches of the soil. Additional passes cause greater increases in bulk density and compact the soil to greater depths (up to 1 foot or more). 2. Primary skid trails receive significant use and exceed 15% bulk density increase and result in detrimental compaction. 3. Where skidders only make 1 or 2 passes over an area the compaction is shallow and the bulk density increase is small. Such areas are expected to return to undisturbed bulk density levels through natural means (frost heave, freeze-thaw and wet-dry cycles, etc.) before the next entry. As such there would be no cumulative impacts on these minimally impacted areas. 4. Secondary and other skid trails, depending on the amount of use, may or may not be compacted beyond the 15% increase in bulk density threshold, however the degree of compaction and the depth of compaction on these skid trails is not expected to recover by natural means by the next entry. These areas will be subject to cumulative impacts with future entries. There are a number of methods available to minimize or mitigate soil disturbance (compaction, displacement, puddling). Any or all of these methods may be appropriate for any given activity area. Dedicated Skid Trails and Endlining: A well planned dedicated skid trail system whereby primary skid trails are spaced approximately 150 to 200 feet apart will result in about 7-15% of an activity area in a detrimentally compacted condition. This compares with about 20-40% of an activity area in a detrimentally compacted condition when random skidding is allowed. In addition random EFFECTS OF TIMBER HARVEST ON THE SOIL RESOURCE ON THE DIXIE NF Updated Jaros 2006 Page 10 of 73

11 skidding can increase the percent of an activity area in a detrimentally compacted condition with each succeeding entry (cumulative impacts). Dedicated skid trail systems require proper planning to ensure they meet the needs of the initial entry as well as any future entries. They serve as an extension of the specified road system. When skidders are restricted to dedicated skid trails and logs are endlined (winched from point of felling to skidder), there is no additional compaction within the activity area and the resulting amount of detrimental compaction will be within the threshold limits. Skidding on Slash: Skidding should be done on slash, where possible, as compaction can be avoided/mitigated. Slash includes not only limbs and other debris from the logging operation, but also thick duff layers and other existing organic debris. These organic materials tend to cushion the effects of the skidder and are effective so long as the machine and the logs being skidded do not break through to mineral soil. Logging slash placed on to skid trails is effective in reducing soil compaction. Mechanical Tillage: Mechanical tillage can be used to loosen compacted soils. Implements used for mechanical tillage should be designed to minimize vertical mixing of soil, leave the majority of duff and forest litter in place, reduce bulk density to near natural levels, loosen soil to a minimum depth of 12 inches, and must be pulled rather than pushed. Mechanical tillage can be used on compacted areas caused by random skidding or other areas of concentrated use to rehabilitate the activity area so it is within the threshold values that have been established, i.e. at least 85% of an activity area in optimum growth condition. Mechanical tillage should not be used on cobbly, stony or rocky soils. Winter Logging: Another method to minimize the areal extent of an activity area subject to compaction is to restrict skidding operations to winter when soils are either frozen or restrict skidding to areas that have a sufficient amount of compacted snow so that skidding operations do not disturb mineral soil. Skidding should be discontinued when frozen ground begins to thaw or when there is too little compacted snow to skid upon (this will avoid the possibility of soil puddling damage). Use of Grapple Skidders Off of Dedicated Skid Trails: Use of grapple skidders off of dedicated skid trails may increase the areal extent of compaction on an activity area, depending on the amount and concentration of use. Dedicated skid trails spaced approximately 150 to 200 feet apart will result in about 7 to 15 percent of the activity area in a detrimentally compacted condition. The primary skid trail system is considered part of the transportation system needed to manage the area. As such, they are treated like roads and are not counted as part of the activity area that must have at least 85 percent in satisfactory condition. However, it should be noted that even though it is a Ranger District decision as to how much of an activity area can be dedicated to the EFFECTS OF TIMBER HARVEST ON THE SOIL RESOURCE ON THE DIXIE NF Updated Jaros 2006 Page 11 of 73

12 transportation system, that area should be the minimum needed to manage the area. The goal should be to keep as many acres as possible in resource production. Where the timber is scattered and logs can be skidded with only one or two passes, compaction damage should be minimal and is expected to recover by natural means by the next planned entry. Where timber is concentrated such as small 3 to 5 acre patch cuts or group selection cuts, a number of secondary skid trails may occur. Areas that receive 3 or more passes will be subject to cumulative impacts with planned future entries. As such these trails will be evaluated to determine which ones will require mechanical tillage to loosen the compacted soils to ensure that at least 85 percent of the activity area has soil properties favorable for optimum plant growth. This determination will be made in conjunction with the Forest soil scientist. If soils are too rocky for tilling, then other alternative methods such as endlining, winter logging, etc. would need to be implemented. To summarize, grapple skidders will be allowed to work off of primary skid trails only where detrimental disturbance will not exceed 15 percent of the activity area. For example, the use of grapple skidders off of primary skid trails is acceptable when soils are frozen or there is sufficient snow to avoid compaction/puddling. Grapple skidders may be used off of primary skid trails when operating on slash so that mineral soil is not exposed. Grapple skidders may be used in areas where there is sufficient surface rock fragments to cushion the skidders from causing unacceptable compaction or soil displacement. (It should be noted that other factors such as residual stand protection may negate the use of grapple skidders off primary skid trails even though soil disturbance thresholds may not be exceeded.) (In the NEPA process when alternatives are formulated, the IDT should stipulate on a stand by stand or cutting unit basis what types of equipment restrictions apply and the reasons for those restrictions.) DIXIE NF LAND MANAGEMENT PLAN The Dixie NF LMP lists a number of standards and guidelines that are designed to protect the soil resource and ensure that Regional soil quality standards are met to maintain long-term soil productivity. Following is a list and description of those standards and guidelines. General Forest Direction: (applies to all Management Areas) Desired Future Condition: -Areas available for timber harvest will generally include slopes less than 40 percent. Some slopes over 40 percent will be available for cable logging (p.iv- 21). EFFECTS OF TIMBER HARVEST ON THE SOIL RESOURCE ON THE DIXIE NF Updated Jaros 2006 Page 12 of 73

13 -Water quality and soil productivity will be maintained (p.iv-22). -Condition of riparian areas will be maintained or if necessary improved (p.iv- 22). Management Area Direction and Standards & Guidelines: -Identify lands available and suitable for timber production on a sale-by-sale basis (p.iv-37). -Minimize soil surface compaction and disturbance by curtailing logging activities during periods of high soil moisture. Design skid trail system to minimize extent of area impacted (IV-40). -Do not apply final shelterwood removal cut until the desired number (as specified) of well-established seedling/acre are expected to remain following overwood removal (IV-41). -Where appropriate, use K-V funds for soil and water rehabilitation and/or wildlife habitat improvement (IV-41). -Special protection and management will be given to land and vegetation for a minimum of 100 feet from the edges of all perennial streams, lakes and other bodies of water or to the outer margin of the riparian ecosystem if wider than 100 feet (p.iv-41). -Design and implement activities in management areas to protect and manage riparian ecosystems (IV-41). -Prescribe silvicultural systems to achieve riparian area objectives (IV-42). -Locate and construct arterial and collector roads to maintain basic natural condition and character of riparian areas (IV-42). -Locate roads outside of riparian areas except for stream crossings where other feasible alternatives do not exist (IV-42). -Select stream crossing points to minimize bank and channel disturbance (IV-42). -Evaluate all management activities within 100 feet of any spring for impacts on spring flow, riparian habitat and soil disturbance (IV-43). -Rehabilitate disturbed areas that are contributing sediment directly to perennial streams as a result of management activities to water quality and re-establish vegetation cover (IV-43). EFFECTS OF TIMBER HARVEST ON THE SOIL RESOURCE ON THE DIXIE NF Updated Jaros 2006 Page 13 of 73

14 -Reduce to natural rate any erosion due to management activities in the season of disturbance and sediment yields within one year of the activity through necessary mitigation measures such as water barring and revegetation (IV-43). -Maintain soil productivity, minimize man-caused soil erosion, and maintain the integrity of associated ecosystems (IV-48). -Use site preparation methods which are designed to keep fertile, friable topsoil essentially intact. -Give roads and trails special design considerations to prevent resource damage on capability areas containing soils with high shrink-swell capacity. -Provide adequate road and trail cross drainage to reduce sediment transport energy. -Revegetate all areas capable of supporting vegetation, disturbed during road construction and/or reconstruction to stabilize the area and reduce soil erosion. -Provide natural channel drainage and establish protective vegetative cover on all new roads or equipment ways, and all existing roads which are being removed from the transportation system. -Minimize soil compaction by limiting vehicle travel; skidding on snow, frozen or dry soil; or using off-ground logging systems. -Restore disturbed soil areas caused by human use to soil loss tolerance levels commensurate with the natural ecological processes for the treatment areas. -Limit intensive ground disturbing activities on unstable slopes and highly erodible sites. -Apply Packer's Guides in designing for crossdrain spacing and buffers. -Chisel or rip compacted soils. -Identify at the project level, upland areas that are immediately adjacent to riparian (prescription 9A) management areas. Adjacent upland areas are those portions of a management area which, when subjected to management activities, have a potential for directly affecting the condition of the adjacent riparian management area. The magnitude of effects is dependent upon slope steepness, and the kind, amount, and EFFECTS OF TIMBER HARVEST ON THE SOIL RESOURCE ON THE DIXIE NF Updated Jaros 2006 Page 14 of 73

15 Management Area 9A: Desired Future Condition: location of surface and vegetation disturbance within the adjacent upland unit (IV-49). -Identify extent of adjacent upland areas using guides on page IV-49 of Dixie LMRP. -Reduce, through designed management practices and appropriate erosion mitigation and vegetation/restoration measures, the project caused on-site erosion rates (calculated with appropriate universal soil loss equation methodology) by 75% within the first year after disturbance. Reduce project caused on-site erosion by 95 percent within five years after initial disturbance. -Avoid, where possible, locating roads on geologic contact zones(e.g. Wasatch/Kaiparowits contact, Carmel/Navajo contact, etc.) If roads must be located in these zones, road cuts should be kept to a minimum height, roads should follow the slope contour, road width should be kept to a minimum and fill should be used to cross highly susceptible mass movement areas rather than cutting into the slopes (IV-50). - Limit use of prescribed fire on areas in or adjacent to riparian areas to protect riparian and aquatic values ((IV-55). -Riparian ecosystem remains healthy and viable. Water quality is not impaired below existing levels and is improved in some areas. Stream channel stability is maintained, or in areas where it is severely degraded, is improved to at least minimally acceptable standards (p.iv-135). Management Area Direction and Standards & Guidelines: -Forest riparian ecosystems are treated to improve wildlife and fish habitat diversity through silvicultural objectives. Timber harvest and other vegetation treatments are used to achieve multi-resource benefits emphasizing riparian values (p.iv-135). Maintain proper stocking and livestock distribution to protect riparian ecosystems (p.iv-138). -Prohibit log landing and decking areas within the riparian area (p.iv-139). -Limit skidding equipment within the riparian area. Do not skid logs across live stream channels or wetlands (p.iv-139). EFFECTS OF TIMBER HARVEST ON THE SOIL RESOURCE ON THE DIXIE NF Updated Jaros 2006 Page 15 of 73

16 SOIL AND WATER CONSERVATION PRACTICES Forest Service Handbook (Soil and Water Conservation Practices Handbook) was established to develop site specific soil and water conservation practices for use on National Forest System lands in the Rocky Mountain and Intermountain Regions to comply with direction in the Clean Water Act. The objective of the handbook is to present a process to develop site specific conservation practices for use on National Forest System lands to minimize effects of management activities on soil and water resources, and to protect water-related beneficial uses. The Handbook is a supplemental document to all Forest Plans. A list of the Soil and Water Conservation Practices used on the Dixie National Forest to minimize the adverse impacts to the soil and water resource caused by timber harvest and road construction activities is contained in the appendix. SOIL RESOURCE INVENTORY: A soil resource inventory has been completed on the Dixie NF. The inventory identifies the kinds of soils that occur on the landscape through transecting, traversing and observations. Pedon descriptions are collected to document the physical and chemical soil characteristics of the various soil types. Full characterization samples are collected and analyzed for selected soils that represent extensive soil types on the Forest. Soil interpretations have already been, or are in the process of being, developed based on the physical and chemical properties of each soil. These interpretations rate the soils for their suitability or limitation for various uses. NFMA/NEPA ANALYSIS During the last 25+ years soil scientists working on the Dixie NF have provided soil input to a variety of resource management projects (timber sales, watershed improvement projects, wildlife & fisheries habitat improvement projects, chainings, prescribed burning, oil & gas projects, mining, wildfire rehabilitation, road construction, building site locations, trail construction, ski area development, campgrounds, recreation areas, wilderness, etc.). Project level soil input consisted of participating as an ID Team member and analyzing the effects of the proposed management activity on the soil resource, as well as recommending appropriate mitigation to minimize the adverse impacts. During this period work was completed on over 120 timber sale projects. Through research conducted by Universities, Experiment Stations, etc. as well as local experience gained through monitoring, a great deal of knowledge has been accumulated EFFECTS OF TIMBER HARVEST ON THE SOIL RESOURCE ON THE DIXIE NF Updated Jaros 2006 Page 16 of 73

17 concerning the impacts of timber harvest and road construction of the soil resource and the effect on long-term soil productivity. Research and years of experience have identified a wide variety of mitigation measures (Soil and Water Conservation Practices, Best Management Practices, etc.) that are available to ensure that the soil and water resource receives proper protection when resource management projects are implemented. Two of the principal sources used for recommending mitigation are: 1. R4 Technical Guide - Erosion Prevention And Control On Timber Sale Areas. 2. FSH Soil And Water Conservation Practices Handbook Over the last few years soil scientists completed detailed soil erosion calculations, using information from the soil inventory and methodologies described in "Estimating Soil Erosion Losses From Utah Watersheds" (Tew, 1973) and the USFS R1/R4 Guide For Predicting Sediment Yields From Forested Watersheds, for estimating erosion associated with timber harvest and road construction on 14 major timber sales. These sales covered over 66,000 acres of NF lands. The soils of 74 soil map units were analyzed. Project Acres Soil Map Units Brian Head 2, , 204, 223, 233, 237, 238, 239, 242, 242A, 269, 505, 646, 648, 651, 654, 655, 657, L402 Ice Caves 3, , 231, 231A, 236 Midway Face , 204, 242 Sidney Valley 6, , 223, 233, 237, 238, 238A, 239, 242, 242A, 242B, 249, 264, 264A, 267, 269, 505 Strawberry 4, , 229, 231, 236, 241 Tippets Valley 3, , 220, 221, 232, 233, 234, 236, 237, 238, 242, 264, 267, 269, 277 Straight Canyon 3,500 P62, P63, P77, P106, P107, P133, P140 Coyote Hollow 2, , 507, 508, 509 Jacobs Swale 15, , 471, 478, 479, 480, 501, 505, 508, 528, 548, 602, 603 LBS , 524, 532, 539, 543, 545 Pacer 3,364 L307, L310, 480, 505, 508, 550 EFFECTS OF TIMBER HARVEST ON THE SOIL RESOURCE ON THE DIXIE NF Updated Jaros 2006 Page 17 of 73

18 Roundy 4, , 480, 508 SCUB 6,831 L108, L201, L209, L210, L301, L302, L304, L306, L314, L315, L316, L319, L401, L402, L403, L404 North Slope 7, Estimated on-site soil erosion was calculated for each soil based on the proposed logging method. This analysis identified soils that were susceptible to irreversible resource damage if logged, based on comparison of on-site soil erosion from logging compared to the soil loss tolerance (T factor) of each soil. Soils that would exceed the T factor if logged were rated as unsuitable forest land. Soils rated as unsuitable because of irreversible resource damage or difficult to regenerate, were either deleted from further consideration for logging, or special mitigation was recommended to ensure that site productivity would not be impaired. A critical watershed area map was prepared for each project area showing the location of sensitive soils, steep slopes, any mass stability problem areas, riparian/wetland areas, and any other special problem areas such as improperly located or drained roads, gullies, etc. Based on erosion modeling and identification of sensitive areas (from soil and water resource standpoint), a set of mitigation measures was recommended for implementation to ensure soil and water resource protection. The analysis of the 14 timber sale projects showed that, with implementation of the recommended mitigation, the impacts associated with the proposed management activities (Proposed Action as well as all Alternatives) would not exceed Soil Quality Standards, i.e. the adverse impacts would be within acceptable limits, and long-term soil productivity would be maintained. It should be noted that based on the analysis, some soils originally proposed for treatment, had to be deleted from consideration for logging so as not to exceed Soil Quality Standards. In other cases, additional alternatives or mitigation were proposed so that the adverse impacts would be within the acceptable range. Since 2003, soil scientists have completed detailed soil monitoring of timber sales across the forest, on 10 major timber sales. These sales covered approximately over 5,000 acres of NF lands. The soils of 9 soil map units were analyzed. Monitoring Project Rendezvous Salvage Timber Sale Soils Monitoring, 2005 Recap Salvage Timber Sale Soils Monitoring, 2005 Rhyolite Salvage Timber Sale Soils Monitoring, 2004 % Detrimental Disturbed Soil Soil Types Documented 5.1% % % 237 EFFECTS OF TIMBER HARVEST ON THE SOIL RESOURCE ON THE DIXIE NF Updated Jaros 2006 Page 18 of 73

19 South Creek Salvage Timber Sale Soil Monitoring, 2004 Hancock Peak Timber Sale Soils Monitoring Project, 2003 Roundy Timber Sale Soil Monitoring Project, 2003 South Creek Salvage Timber Sale Soil Monitoring Project, 2003 Under Barney Timber Sale Soil Monitoring Project, 2003 Dry Lakes Timber Sale Soil Monitoring Project, 2003 Coyote Hollow Timber Sale Soil Monitoring Project, % L % 233, 237, % % L % L201, L315 22% 539 5% 508 Typically 7 percent of these sales had detrimental soil disturbance. This is well within the guideline of less than 15 percent of an activity area should have detrimentally disturbed soil after the completion of all management activities SUMMARY: There have been numerous research studies analyzing the impacts of timber harvest and road construction on soils. Many of these studies have analyzed kinds of equipment or methodologies that minimize the adverse impacts. Based on this research a wide variety of mitigation measures have been formulated that will minimize the adverse impacts to the soil and water resources. The Dixie NF has been implementing soil and water conservation practices for many years. Monitoring has been conducted for several years and has shown that: 1. Soil and water impacts associated with timber harvest and road construction have been analyzed in NEPA documents. 2. Mitigation has been recommended to ensure that adverse impacts to the soil and water resource are within an acceptable range. 3. The mitigation was brought forward into the timber sale contract. 4. The mitigation has been implemented and that it has been effective in providing the protection it was intended to do. As research or local experience identifies new and/or improved practices, they are adopted and implemented. There are a number of examples of this on the Dixie. For example, when research conclusively showed that compaction was a serious and widespread effect of ground based logging equipment, the Dixie adopted several mitigation measures that would minimize the amount of compaction so that it would not exceed the thresholds established in the Soil Quality Guidelines. The use of dedicated skid trails and endlining was implemented. Winter logging alternatives were also proposed. More recently, research has shown that mechanized EFFECTS OF TIMBER HARVEST ON THE SOIL RESOURCE ON THE DIXIE NF Updated Jaros 2006 Page 19 of 73