ClwLandtype_20121207

Metadata:

• Identification_Information
• Data_Quality_Information
• Spatial_Data_Organization_Information
• Spatial_Reference_Information
• Entity_and_Attribute_Information
• Distribution_Information
• Metadata_Reference_Information

Identification_Information:

Citation:

Citation_Information:

Originator: Clearwater National Forest

Publication_Date: 2007

Title: ClwLandtype_20121207

Geospatial_Data_Presentation_Form: vector digital data

Online_Linkage:

\\ds.fs.fed.us\EFS\FS\NFS\NezPerceClearwater\Program\7140Geometronics\GIS\WebSupport\Landtype\Clearwater\ClwLandtype_20121207.shp

Description:

Abstract:

Clearwater National Forest Landtypes, Landtype Associations, Landtype Association Groups 10/1/2009
Land System Inventory completed by Dale Wilson, Soils Scientist, Clearwater NF 1983-1993 Updates and Edits by Jim Mital, Soils Scientist, Clearwater NF 1993-present. Last update 10/1/09 added fire intervals

Purpose:

INTERPRETATIONS
Clearwater National Forest Land System Inventory 1983
Interpretations presented in this report are intended to aid the user in predicting the response of landtypes to various types of management activities. They are intended to be used as guides for various levels of planning, down to, and including, early stages of project planning. They should not be used to make detailed project plans or decisions until they have been field checked and verified.
WATERSHED INTERPRETATIONS
The Clearwater National Forest comprises a major part of the watershed area which contributes to the Clearwater River drainage system. The headwater streams within this survey area are important spawning habitat for steelhead and chinook salmon. Resident fish populations include eastern brook trout, cutthroat trout and rainbow trout. Downstream, water uses are comprised mostly of hydroelectric power generation, irrigation, and recreation. Thus, maintaining water quality by controlling erosion and sediment is an objective of Forest management.
Under natural conditions, these Forest watersheds produce sediment at estimated rates of 10 to 100 tons per square mile per year. Generally, natural sediment is produced by stream channels.
When the soils are disturbed by runoff, surface erosion and mass wasting can occur. The extent to which transported soil particles become sediment depends, in part, on properties of the landform. In describing which landform characteristics play a role in sediment transport, the term sediment delivery efficiency is used to predict how effectively sediment is transported from the source to streams and rivers. Stability interpretations do not necessarily indicate the magnitude of a problem, but they do indicate the likelihood of the problem. Landtypes are not homogeneous units of land; they have a range of characteristics. A landtype with a high rating for overland flow erosion does not mean that erosion is occurring evenly over the landtype at a rate more severe than that occurring evenly over a landtype rated low. It does mean, however, that severe erosion is more likely to occur on landtypes rated high than those rated low. Also, it must be remembered that all landtypes may contain inclusions of lands that have different characteristics than those of the mapped landtype. The occurrence and analysis of inclusions must be field verified before project decisions can be made.
This watershed interpretation section presents the rationale used to rate these dominant slope erosion processes on the Clearwater National Forest. These ratings are used as a basis for analyzing the relative stabilities of small watersheds and the acceleration of these processes by management practices. The framework for the interpretation is presented in tabular form in which the landtype properties are described and the potential ratings are divided into relative classes.
Ratings are adjusted for some landtypes with unique properties or where erosional processes repeatedly observed in the field are not explained by the properties listed in the tables.
Erosion potentials for landtypes are rated for undisturbed surface soils, severely disturbed surface soils or subsoils, and exposed substratum layers.
Surface Erosion Potential
The surface erosion potential rating considers raindrop splash and overland flow erosion on soils bared of vegetation, but which retain the root mat and soil structure. This rating is intended for use in predicting surface soil erosion which occurs following broadcast burning or wildfires. Landtype properties used to make these ratings are (1) volcanic ash topsoil characteristics, (2) slope gradient, (3) depth to restricting layers, and (4) slope shape. Volcanic ash plays an important role in the surface erosion rating since this material is extremely permeable, and is seldom associated with overland flow.
Table 1 lists landtype properties and rating classes for surface soil erosion potential.
Notable exceptions to this chart are high elevation ridges and upper slopes where surface erosion has been repeatedly observed, especially in areas burned by wildfires. Landtypes containing compacted tills are also rated higher than indicated on the table, since frequent occurrences of overland flow have been observed during spring snow melt. Landtypes occurring on the west edge of the Palouse District, where soils are developed in loess and lack an ash cap, are rated one class higher than indicated in table 1.
Table 1 - LANDTYPE PROPERTIES USED TO RATE UNDISTURBED SURFACE SOIL EROSION POTENTIAL Potential Classes
Property Low Moderate High
Ash Cap >7" Thick <7" Mixed Ash Missing Ash Missing Slope Gradient Variable >60% 40 to 60% >60% Depth to Restrictive Layer Variable 20 to 40" 20 to 40" <20" Slope Shape Variable Straight Concave & Straight Concave & Straight Subsoil Erosion Potential
The subsoil erosion potential rating considers raindrop splash and overland flow where the subsoil has been exposed or where the surface soil has been severely disturbed and mixed with the subsoil. This rating is intended to predict erosion which occurs following shallow soil disturbance and displacement. Excavated skid trails, fire lines, and high lead yarding corridors can result in this type of erosion. Landtype properties used to make this rating are, (1) slope gradient, (2) depth to restricting layer, and 3) subsoil texture.
Table 2 lists the landtype properties and rating classes for subsoil erosion potential. Exceptions to the ratings in table 2 include soils derived from ancient alluviums, Palouse loesses, grussic granitics, and decomposed Revett quartzites. Field observations indicate these particular soils have high potential for erosion due to their graded particle size distributions.
Table 2 - LANDTYPE PROPERTIES USED TO DETERMINE SUBSOIL EROSION POTENTIAL
Potential Classes
Property Low Moderate High Slope% <40% 40-60% <40% 40 - 60% 60%+ 40 - 60% 60%+ Depth to Restrictive Layer >20" >40" <20" 20 - 40" >40" <20" <40" Subsoil Texture Clay loams, All sl,ls sl, ls All All All skeletal textures alluvium finer than ls and loess sites Substratum Erosion Potential
The substratum erosion potential rating considers raindrop splash and overland flow erosion which occur in deep excavations such as roads and skid trails. Factors used to make this rating include parent material characteristics such as bedrock weathering, rock fragment content, and substratum permeability. Table 3 lists the landtype parent material properties and the classes for substratum erosion potential. Landtypes which have an observed tendency to intercept and concentrate subsurface water in major excavations have been rated one class higher than table 3 would indicate.
Table 3 - LANDTYPE PROPERTIES USED TO RATE SUBSTRATUM EROSION POTENTIAL
Potential Classes
Parent Material Types
Low = Skeletal parent materials including glacial tills and weakly weathered granitics, quartzites Mod = Moderately weathered skeletal siltites and granitics, deeply weathered schists, gneisses, and basalts High = Silty alluviums and Palouse silts. Deeply weathered non-skeletal G series granitics and deeply weathered R series Revett quartzites Very High = Decomposed grussic granitics (all K series) Mass Wasting Potential
The mass wasting potential rating evaluates the relative potential for mass soil movement caused by gravitational forces. Activities such as timber harvest, road construction, and fire have the potential to accelerate mass movement. Landtypes which are susceptible to mass wasting may require special engineering techniques, timber sale prescriptions, logging system layouts, and prescribed burning plans.
The most common forms of mass wasting on the Clearwater are (1) rotational mass wasting, and (2) debris avalanches. The ratings for landtypes consider the potential for natural as well as accelerated mass movement resulting from management activities.





Rotational Mass Wasting
Rotational mass wasting is the movement of the regolith as a coherent mass, usually with a backward tilting motion. Slippages involve subsurface water concentrations. Hard bedrock does not constitute the slippage plane. Factors used to rate the potential for mass wasting are based on the inventory and measurement of some 700 landslides occurring on the Forest in 1974 - 1976.
Landtype properties used to rate rotational mass wasting potential are (1) slope gradient, (2) presence of concentrated subsurface ground water using slope dissection and water table presence, (3) substratum texture, (4) regolith depth, and (5) presence of mica.
Table 4 lists the landtype properties and rating classes for rotational mass wasting potential.
Landtypes which are identified as having a history of mass movement are placed in the mass wasted landform (landtype 50) group. These landtypes are variable and require investigation in the field. Because of historic instability, these landtypes are rated as having high mass wasting potential. Some high elevation landtypes are rated one class lower than indicated on table 4 because late winter or early spring rain or snow and snow melt events are much less frequent and because the frost churning increases the internal strength of the soil mantle. Landtypes developed in weakly weathered quartzites are rated one class lower than indicated in table 4.


Table 4 - LANDTYPE PROPERTIES USED TO RATE ROTATIONAL MASS WASTING POTENTIAL

Low Moderate High Very High Slope Gradient <40% 40 - 60+% <40% 40 - 60% 60+% 40 - 60% 60+% 60+% 60+%
Dissections Dissected Dry Wet Dissections Dissections Dissected Dissected Non- Dissected Wet Dissection Dissected Non Dissected Dissected Dissected Wet Dissected
Texture All sl & ls All All sl & ls All All sl & heavier All sl & ls sl & heavier All Regolith Depth All <60"

60"	
60"	
60"	

<60%

60"	
60"	
60"	
60"	
60"	
60"

Presence of Mica All No All Yes No No All Yes All No Yes All

Debris Avalanche
Debris avalanche mass wasting is characterized by rapid and usually sudden downslope movement of initially consolidated debris. The slippage plane is usually hard bedrock. Debris avalanches often turn into mud flows as they move down slope and accumulate soil material. The landslide inventory of 1974-1976 identified several landtype properties which are associated with debris avalanches, and these are used to rate the potential for debris avalanches. These properties include (1) slope gradient, (2) slope shape, (3) topsoil texture, and (4) the occurrence of old slide scars and accumulations of debris at the slope base. Table 5 lists the landtype properties and rating classes for debris avalanche potential.






Table 5 - LANDTYPE PROPERTIES USED TO RATE DEBRIS AVALANCHE POTENTIAL
Property Low Moderate High
Slope <40% 40 - 60% 40 - 60% 60%+ 60%+ 60%+
Slope Shape Variable Convex Convex & Straight Concave & Straight Concave Straight Topsoil Texture Variable cl & sil sl & ls sil & l sl & ls sl & ls Occurrence of old slide scars Rare Rare Common Common Many Many

Slope Sediment Delivery Efficiency
Slope sediment delivery efficiency is the ability of a landtype to deliver sediment produced on site from the source to streams. The delivery efficiency rating reflects the delivery of naturally produced sediment on slopes as well as the acceleration of mass movement through management activities. Landtype properties used to make this rating include (1) slope gradient,(2) slope dissection, and (3) slope shape.
Table 6 lists landtype properties and rating classes for slope sediment delivery efficiency. Exceptions to the ratings in table 6 occur where steep slopes, which ordinarily would have high delivery ratings, are separated from streams by low gradient depositional areas. Examples include steep glacial trough walls (Landforms 48, 49) which are separated from major streams in valley bottoms by a broad expanse of valley train glacial till in the trough bottom. Other exceptions include floodplain, bottomland, and recent terrace landforms (Landform 10, 11) which, because of their unique position in close proximity to major streams and rivers, have a high potential for sediment delivery.

Table 6 - PROPERTIES USED TO RATE SLOPE SEDIMENT DELIVERY EFFICIENCY

Property Low Moderate High Very High
Slope % <20% 20-40% 40 - 60% 40 - 60% 40 - 60% 60+% 60+% Slope Dissection All Weak High Weak Dissected Non dissected Dissected Slope Shape Flat & Compound Convex Compound Convex Straight & Concave Straight Straight & Concave

Slope sediment delivery efficiency is increased when roads are constructed in steep, mountainous terrain. Road prisms are designed to be efficient transporters of sediment. Slope gradients on cuts and fills are significantly steeper than the natural slopes, and this excavated road prism increases overland flow and thus, sediment production. Road prisms effectively increase the drainage density of a landform by adding the channeling of ditches and road surfaces. Increases in sediment delivery efficiency can be estimated by using the average distance of the road from a line stream along with the dissection density which determines the number of drainage crossings.
ENGINEERING INTERPRETATIONS
Roading Suitability
Roading suitability refers to watershed risks associated with road construction in the various landtypes. It is a combination of potential onsite erosion with the slope sediment delivery efficiency. This assumes that mass erosion and road prism rill and sheet erosion play a role of equal importance in stream sedimentation. Actually the role of the two sediment sources will vary according to landtype. However, it has been shown that very high sediment rates from either source can cause severe watershed damage. The following assumptions are used as a base for rating road suitability.

1. Road suitability is the ability of the land to support construction of a "basic road" without large failures of cut and fill slopes, without severe surface erosion of the road prism, and without allowing material to reach stream courses if such damages occur. It presumes a road is located, designed, constructed without any special precautions (such as binwalls, flatter cut slopes, hand planting to revegetate slopes, etc.) to prevent landslides or surface erosion, except as stated in the "basic road" definition. Construction costs are not considered in road capability, nor are such factors as wildlife and esthetics considered.
2. The "basic road" is defined as a 14' subgrade, 3/4:1 cut slope, 1 1/3:1 fill slope, with uncompacted fills, no surfacing, and where needed, ditches, curve widening, and turnouts. All clearing slash is removed from the road prism. On the sideslopes, balanced construction is practiced as much as possible. Grass is seeded on exposed soil by hydro or hand.
3. Potential impacts and probabilities of encountering problems increase with greater road widths, stricter alignment standards or when roads are constructed on steeper slopes. Impacts and problems also increase where the quality of road construction is below that for the "basic road". Ratings for a landtype use landtype characteristics that are average or typical for that landtype. Considerable variations in roading capability exist within any given landtype, and must be fully considered in detailed planning.
Road suitability rating class is determined by evaluating the rotational mass wasting potential and debris avalanche potential (which ever is highest) and substratum erosion hazard with slope delivery efficiency. The resulting roading suitability classes are defined as follows:

A. Roading Suitability Classes
Class 5 - Virtually no risk of landslides and/or surface erosion with very low potential of material reaching stream courses. Consequences of mistakes are minor and easily corrected.
Class 4 - Low risk of landslides and/or erosion with low potential of material reaching stream courses. Risk can usually be almost eliminated by careful roadbuilding practices. Consequences of mistakes are seldom severe, and can be corrected.
Class 3 Moderate risk of landslides and/or surface erosion with moderate potential of material reaching stream courses. Reduction of risk is possible, although it may be costly. Mistakes may have severe consequences, but can usually be corrected.
Class 2 High risk of landslides and/or surface erosion, with some material reaching stream courses. Reduction of risk is difficult and costly. Mistakes usually have severe consequences, and are difficult to correct. Class 1 - Extremely high risk of landslides and/or erosion, with material reaching stream courses. Reduction of risk is very difficult, and is often not possible. Mistakes have severe consequences, and are often impossible to correct. B. Road Construction Cost Class
This rating is intended to enable transportation planners to compare cost of a "standard road" built on various landtypes. Average cost per mile of road in a landtype using 1) slope gradient, 2) slope dissection density, 3) soil mantle (regolith) depth, 4) percentage rippable material, 5) cost of measures necessary to overcome mass wasting hazard, and 6) cost of measures necessary to overcome surface erosion for that landtype. Costs are in 1982 dollars and are given in 5 classes. A rating of class 1 is given to landtypes with the lowest construction cost and a rating of class 5 is given to landtypes with the highest construction cost. Classes use a geometric progression of costs with a common ratio of 1.5:l. Road construction cost classes for the "basic road" in $1000's/mile are:
Class I - 21.1 to 31.9 Class 2 - 32.0 to 48.2 Class 3 - 48.3 to 72.8 Class 4 - 72.9 to 109.9 Class 5 - 110.0 to 166.1 Road Maintenance Interpretations
The major soil characteristics effecting road maintenance are road prism erosion and trafficability. Road prism erosion is evaluated using parent material erosion hazard rating.
C. Trafficability
This rating is designed to predict which soil types are susceptible to damage due to heavy machinery traffic under wet conditions. This rating is general in nature and considers soil texture, coarse fragment content, and size of coarse fragments. This rating defines the susceptibility of road surfaces to rutting and traction problems if used when wet. Most soils on the Forest have a one to two-foot thick ash cap. This material should not be used as running surface material because of its extremely low bearing strength and tendency to dust. Only the characteristics of the subsoils and parent materials are used in this rating. Classes are:
Good - Loamy skeletal textural families with coarse fragments 3/4" diameter and larger and treads built in hard well fractured bedrock. Contains unified texture classes GW, GC, & SW.
Fair - Coarse loamy, sandy and loamy skeletal textural families with coarse fragments less than 3/4" diameter. Contains unified texture classes GP, SP, GM, & SM.
Poor - Other finer textured non-skeletal soils. Contains unified texture classes CL, ML, MH, & CH.
D. Other Road Maintenance Factors
Several other factors influencing road maintenance are listed by designated landtype but are not rated. The listing should be considered when making road maintenance evaluations for landtypes. Additional listed factors are:
1. Cutbank Sloughing - Refers to relatively small slumps, usually less than 10 cubic yards, which remain on the road. Characteristics conducive to cutbank sloughing are: Deep silty soils, deep unconsolidated deposited soils, soils with fragipans and mapping units with common high water tables.
2. Dry Cutbank Raveling - Refers to single particle detachment and ravel. Grussic granitic soils are the primary source of this problem.
3. Rapid Brush Encroachment is common on landtypes with common wet or very moist soil conditions and SAF/Mefe and SAF/Pamy habitat types.
4. Fill Sloughing - Materials most conducive to fill sloughing are moderately and well weathered mica shists and coarse textured cohesionless materials from deeply weathered gneisses, granitics, and quartzites.
5. Tread wear in bouldery material - This refers to materials that contain large percentages of rounded and subrounded bouldery material. Heavily used roads in these materials with natural surfaces experience rapid cushion wear, leaving very rough unbladeable surfaces.
6. Road tread erosion and rutting.
7. Severe dust problems - This is confined largely to soils with silty textures.
E. Rippability
Rippability ratings presented here are based on the type of parent material and the degree of weathering of residual parent material. Ratings are given in three general classes for excavation required for the "basic road" previously described.
Class 1 - Mostly rippable (>90%) - Includes all unconsolidated depositional and landforms 22 and 24 with deeply weathered parent material. (Seismic velocities >4500 feet per second)
Class 2 - 50 to 90% rippable - Includes landtypes with deep colluvial and frost churned mantles. Parent material weathering is variable. (Seismic velocities between 4,500 and 10,000 feet per second)
Class 3 - <50% rippable - Includes steep slopes with shallow mantles over weakly weathered parent material and glacially scoured areas with shallow mantles. (Seismic velocities 10,000 feet per second)

F. Unified Soil Classification
Unified ratings are listed for subsurface soil horizons (subsoil and substratum) to provide engineers with estimated soil properties which affect road construction. These ratings are based on soil textures and rock fragment content. Several ratings are given for a landtype where soils have a wide range of properties or where two or more distinct soil types occur within a landtype.
SILVICULTURE INTERPRETATIONS
Landtype Timber Productivity
Timber productivity classes used on the Clearwater National Forest are based on data obtained in the 1973 Forest Inventory. Yield classes are stratified by vegetative habitat types. This rating integrates productivity ranges established for habitat types with climate, soil moisture holding capacity, and overall soil fertility.
Class 1 - 225+ cubic feet/acre/year
Landforms 22 and 24 with soils derived from ancient alluvium and Palouse loess.
Class 2 - 165 to 224 cubic feet/acre/year
Landforms 22 and 24 with WRC/PAMY habitat types and soils with thick ash caps and developed from parent materials other than ancient alluvium and Palouse loess. Steep, northerly slopes with WRC/PAMY habitat types and deep colluvial soils.
Class 3 - 100 to 164 cubic feet/acre/year
Steep southerly slopes below 5,000 feet elevation with deep colluvial soils and ash caps over 7 inches deep.
Landtypes with SAF/PAMY habitat type.
Landtypes occurring below 4,800 feet elevation having shallow fragipans (20 to 40 inches deep).
Landtypes in low precipitation zones along the western fringes of the Palouse District.
Landtypes below 4,800 feet elevation with 15 to 40% Umbrepts and/or poorly drained soils.
Class 4 - Below 100 cubic feet/acre/year
Landtypes with SAF/MEFE and SAF/XETE habitat types.
Landtypes above 4,800 feet elevation with 15 to 40% Cryumbrepts and/or seasonal high water tables.
Landtypes on steep southerly slopes containing at least 25% shallow, droughty soils and bedrock outcrop.
Class 5 - Noncommercial Forest Land
Landtypes placed in this category because of both low productivity and regeneration problems.

Regeneration Limitations
The following is a listing of recognized or suspected soil related regeneration problems common to the Clearwater National Forest. No attempt is made to rate the severity of the problem or suggest mitigation for the problem. This must be done on a site by site basis.
0 - No recognized inherent soil related regeneration problems.
1 - Shallow and/or droughty soils with bedrock outcrop.
2 - Soils with good soil moisture holding and fertility regimes, but in low precipitation zones on the western and southern edges of the Palouse District.
3 - Landtypes with "umbric" soils occurring over a significant portion of the unit.
4 - Seasonal or continuous high water tables occurring over a significant portion of the unit.
5 - Severe climax brush, sod, or fern competition.
6 - Large percentage of surface rock fragments.
7 - High energy slopes with insolation problems.
Soil Sensitivity to Disturbance
Certain soils on the Forest have surface and underlying subsoil horizons which are highly contrasting in terms of physical and chemical properties. Where volcanic ash overlies grussic granitic subsoils, for instance, the ash is relatively fertile with good moisture holding properties, while the underlying sandy "grus" is essentially sterile and has a low moisture holding capacity. Such a soil could be significantly damaged if the topsoil was removed or displaced through tractor site preparation and slash disposal. This sensitivity rating is designed to identify these soil types and consists of three classes listed below.
Low - Differences between surface soil and subsoil moisture holding capacity and fertility are minor. Surface soil disturbance is of little consequence in relation to productivity if subsoils are not compacted. Most landtypes in this rating class are alfisols derived from ancient alluviums, Palouse loess and deeply weathered schists.
Medium - Differences between surface soil and subsoil moisture holding capacity and fertility are significant. Severe surface soil mixing and/or removal could reduce long-term productivity.
High - Differences between surface soil and subsoil moisture holding capacity and fertility are major. This rating applies to landtypes where ash caps overlie decomposed granitics and quartzites, or have shallow (<20" deep) fragipans. It also applies to high elevation landtypes with excessively well drained subsoils.
Prescribed Burning Guides
These guides are designed to provide recommendations for prescribed burning on landtypes and are based primarily on the work of Al Harvey of the Intermountain Forest Experiment Station in Moscow, Idaho. The burning classes are designed to recommend fire intensities and residual fuel levels necessary to maintain a soil organic base adequate to sustain soil microbial populations at acceptable levels.
Class 1 - Deep moist soils on low energy slopes with WRC/PAMY habitat type.
Activity fuel load - 0 to 25 tons/acre Fireline intensity - Up to 1,000 BTU's/sec/ft. with 8 to 11 feet flame lengths

Class 2 - Deep soils on high energy southerly slopes with WRC/PAMY habitat type.
Activity fuel load - 10 to 20 tons/acre Fireline intensity - Up to 600 BTU's/sec/ft with 4 to 8 feet flame lengths.

Class 3 - Shallow, droughty soils on high energy south slopes with GF/PAMY and DF habitat types.
Activity fuel load - 10 to 15 tons/acre Fireline intensity - Less than 100 BTU's/sec/ft. with < 4-foot flame lengths

Class 4 - High elevation soils with SAF/XETE habitat type.
Activity fuel load - 15 to 25 tons/acre leave duff Fireline intensity - Less than 100 BTU's/sec/ft. with < 4-foot flame lengths

Class 5 - High elevation soils with SAF/MEFE + PAMY habitat types.
Activity fuel load - Less than 10 tons/acre Fireline intensity - Less than 600 BTU's/sec/ft. with 4 to 8 feet flame lengths

Logging Suitability Class
This is a general grouping of dominant slope and landform characteristics influencing the use of presently available and foreseeable skidding systems used on this Forest. Other limitations specific to a certain logging method, such as soil compaction and wet areas, may also occur in the landtype, but are listed as separate interpretations.
Class I - Weakly dissected or incised slopes with less than 40 percent gradients. This class is largely adapted to tractor type skidding methods.
Class 2 - Broken, dissected, low and moderate relief landforms with a variety of slope shapes and gradients. Combinations of short line and tractor systems are adaptable to these landforms.
Class 3 - Long, straight, and concave slopes with greater than 40 percent slope gradients generally suitable for midslope roads. Line systems using the midslope roads are adaptable to this class.
Class 4 - Long, straight, and concave slopes with greater than 40 percent slope gradients and are marginally suitable for high risk midslope road construction. Long line systems using ridge top, or lower slope margin roads, or aerial systems using no roads are adaptable to this class.
Windthrow Susceptibility Class
Windthrow is rated only as average and high. Landtype characteristics contributing to high windfall susceptibility are units with common high water tables and soils with fragipans.
SOIL COMPACTION
Forest managers are becoming increasingly aware that operating heavy equipment on Forest lands has the potential to compact surface soils. Problems associated with compaction include reduced water infiltration, reduced soil moisture retention, increased overland flow with related erosion, and the restriction of plant root growth.
The surface soils of the Clearwater National Forest are somewhat unique in that they often consist of volcanic ash which was deposited several thousand years ago. This ash topsoil is typically light, fluffy material with a low bulk density and a very high infiltration rate for water. On much of the Clearwater, the ash surface soil is greater than one foot thick. Where the ash soil is relatively pure and undisturbed, bulk densities range from .65 to .85 grams/centimeter3, with an average value of about .75 grams/centimeter3.
Local studies designed to evaluate effects of tractor site preparations and slash disposal have shown that tractor operations increased the bulk density of pure ash to approximately .85 grams/centimeter3. In this case, the area was disturbed, but the ash was not displaced. In areas where the disturbed ash was less than 11 inches thick, bulk densities were increased to from .9 to 1.1 grams/centimeter3.
In an attempt to relate soil densities to tree growth, the Potlatch Corporation has conducted greenhouse seedling growth studies in soils with various levels of compaction. In these trials, soil bulk densities of .70, .95, and 1.2 grams/centimeter3 were used. Results showed that significant reductions in seedling root growth were observed in soil bulk densities of .95 grams/centimeter3 or greater.
Ash topsoil displacement and compaction in repeatedly used skid trails has been shown to result in soil densities which can inhibit seedling root growth. For this reason, it is recommended that designated skid trails be used with spacings of at least 100 feet. Such a system should reduce widespread compaction which results from uncontrolled broadcast skidding, thus reducing soil damage.
Tractor slash disposal and site preparation operations also have potential for surface compaction and displacement. In the local study, between 40 and 46 percent of total area was disturbed during slash disposal. Soil density was closely related to degree of soil displacement. After all treatments, 30 percent of measured points had ash displaced to depths less than 11 inches. Bulk densities of ash less than 11 inches were increased 30 percent above those of undisturbed ash. Bulk densities of ash greater than 11 inches deep increased 12 percent over those for undisturbed ash. Bulk densities of .90 grams/centimeter3 were reached on two of three sites where disturbed ash depths were less than 11 inches in depth.

PRESCRIBED FIRE - LANDTYPE HAZARD GROUP Fire Erosion Risk
GROUP 1 - These could be referred to as red flag landtypes. They have a high hazard for surface erosion or debris avalanches following burns. This, their size arid proximity to other resources should be a major consideration when decisions for prescribed fire or appropriate suppression response are made. It should be anticipated that some rehabilitation may be necessary if these landtypes burn.
GROUP 2 - These landtypes have small percentages that are susceptible to surface erosion and debris avalanches following burns. This Is especially true if the potential for a hot fire exists. The presence of these landtyp6s should be considered when making the decision to let a fire burn but not to the extent of those in Group 1. Rehabilitation probably won't be necessary under normal conditions.
GROUP 3 - All other landtypes.
lthaz.dbf
Column headings in dbf files are limited to 10 characters. Below is a translation of the columns in the lthaz.dbf
Translation Column ----------------------------------- ---------- LANDTYPE landtype , MASS_WASTE_POTENTIAL masswastep, DEBRIS_AVALANCHE_POTENTIAL debris_avp, SURFACE_EROSION_POTENTIAL surf_erosp, SUB_SURFACE_EROSION_POTENTIAL subsurf_ep, PARENT_MAT_EROSION_POTTENTIAL par_mat_ep, SLOPE SEDIMENT DELIVERY EFFICIENCY sd_del_eff, ROAD_SUITABILITY road_suit , ROAD_CONSTRUCTION_COST CLASS road_cnstc, TRAFFICABILITY_CLASS traffic_c , ROAD_MAINTENANCE_FACTOR road_mnt_f, RIPPABILTIY_CLASS rip_c , UNIFIED_SOIL_CLASS unif_soilc, SOIL_PRODUCTIVITY_CLASS soil_prodc, REGENERATION_LIMITATIONS regen_lim , SOIL_SENSITIVITY_CLASS soil_sensc, BURN_CLASS burn_c , WIND_THROW_CLASS windthrowc, LOGGING_METHOD_CLASS log_meth_c, FIRE_EROSION_RISK fr_erosrsk

Time_Period_of_Content:

Time_Period_Information:

Single_Date/Time:

Calendar_Date: 2007

Currentness_Reference: publication date

Status:

Progress: Complete

Maintenance_and_Update_Frequency: None planned

Spatial_Domain:

Bounding_Coordinates:

West_Bounding_Coordinate: -117.001636

East_Bounding_Coordinate: -114.296897

North_Bounding_Coordinate: 47.135743

South_Bounding_Coordinate: 46.090085

Keywords:

Theme:

Theme_Keyword_Thesaurus:

REQUIRED: Reference to a formally registered thesaurus or a similar authoritative source of theme keywords.

Theme_Keyword: landtype

Theme_Keyword: lta

Access_Constraints: none

Use_Constraints:

The Forest Service uses the most current and complete data available. GIS data and product accuracy may vary. They may be: developed from sources of differing accuracy, accurate only at certain scales, based on modeling or interpretation, incomplete while being created or revised, etc. Using GIS products for purposes other than those for which they were created, may yield inaccurate or misleading results. It is highly recommended that before any conclusions or analysis is processed using this data that the data be discussed with a resource specialist in the particular field. The Forest Service reserves the right to correct, update, modify, or replace, GIS products without notification. For more information, contact the Clearwater National Forest Supervisor's Office, Orofino, Idaho, 1-208-476-4541

Point_of_Contact:

Contact_Information:

Contact_Organization_Primary:

Contact_Organization: Clearwater National Forest

Contact_Position: Resource Information Coordinator

Contact_Address:

Address_Type: mailing address

Address: 12730 Hwy 12

City: Orofino

State_or_Province: ID

Postal_Code: 83544

Country: USA

Contact_Voice_Telephone: 208-476-4541

Hours_of_Service: 0800-1600

Native_Data_Set_Environment:

Microsoft Windows Vista Version 6.0 (Build 6002) Service Pack 2; ESRI ArcCatalog 9.3.1.4000

Cross_Reference:

Citation_Information:

Originator: Clearwater Nez Perce Revision Team

Publication_Date: Unpublished Material

Geospatial_Data_Presentation_Form: vector digital data

Data_Quality_Information:

Lineage:

Process_Step:

Process_Description:

Data came as digital line files scanned from 1:24000 quads. Quads were edgematched to each other using TontoCAD and LT Dos. The quads were then imported into ARC/Info, built into polygon coverages, attributed, and appended. Edited by Brent Linder and Dave Emery.

Source_Used_Citation_Abbreviation:

C:\fsfiles\ref\library\gis83\clearwater\geodatabase\metadata_xml\soils\lt_polygon.xml

Process_Step:

Process_Description:

Land Type Association regions are partialy completed. Associations are aggregated in a two step process. First step is an electronic aggregation by model, assigning lt to lta where possible. Second step is a manual assignment by soil specialist. Step two was done project by project as needed. Some land types are specific to a land type association. Some land types are not specific, inclusion into an lta is based on location and other characteristics. Detailed information on the land type / land type association should be obtained from the Clearwater Forest SOil Scientist.

Process_Step:

Process_Description:

11-23-98 Jim Mital,Ed Lozar/Dianne Brower(mapping) Lochsa drainage LTA regions

Process_Step:

Process_Description:

9-7-2000, Sue White vertical integration with 4th level huc boundary along north edge of Powell and North Fork districts.

Process_Step:

Process_Description:

4-23-2002, Sue White added item HAZMW with value 'y' where landtype met Mital's updated hazard criteria - select landtype from lthaz where (mass_waste_pot in ('H','VH')) or (debris_avalanche_pot = 'H') or(sed_del_eff in ('H','VH')). value 'n' added to all others.

Process_Step:

Process_Description:

5-23-2002, Sue White added item HAZSUBSE with value 'y' where landtype met Mital's updated hazard criteria- select landtype from lthaz where (sub_surface_erosion in ('H','VH') or(parent_mat_erosion_pot in ('H','VH'). value 'n' added to all others.

Process_Step:

Process_Description:

2004/2005, Colleen Fahy worked with Jim Mital to complete the LTA's for the roaded area of the Forest (North Fork +), Wilderness still has no LT's but now has LTA based on landform, slope & aspect. New LTA groups not yet added to the Forest LTA description ta

Process_Step:

Process_Description:

2005/2006, Stephanie Grubb edited, updated attributes to coincide with the original cwf_lt cover and to work with analysis tools.

Process_Step:

Process_Description:

9/3/09 CFahy updated to include portions of the Palouse that were missing and edgematched to administrative forest boundary

Source_Used_Citation_Abbreviation: C:\fsfiles\ref\library\gis\clw\metadata_xml\soils\land_type.xml

Process_Date: 20090903

Process_Time: 10555600

Spatial_Data_Organization_Information:

Direct_Spatial_Reference_Method: Vector

Point_and_Vector_Object_Information:

SDTS_Terms_Description:

SDTS_Point_and_Vector_Object_Type: G-polygon

Point_and_Vector_Object_Count: 1742

Spatial_Reference_Information:

Horizontal_Coordinate_System_Definition:

Planar:

Grid_Coordinate_System:

Grid_Coordinate_System_Name: Universal Transverse Mercator

Universal_Transverse_Mercator:

UTM_Zone_Number: 11

Transverse_Mercator:

Scale_Factor_at_Central_Meridian: 0.999600

Longitude_of_Central_Meridian: -117.000000

Latitude_of_Projection_Origin: 0.000000

False_Easting: 500000.000000

False_Northing: 0.000000

Planar_Coordinate_Information:

Planar_Coordinate_Encoding_Method: coordinate pair

Coordinate_Representation:

Abscissa_Resolution: 0.000000

Ordinate_Resolution: 0.000000

Planar_Distance_Units: meters

Geodetic_Model:

Horizontal_Datum_Name: North American Datum of 1983

Ellipsoid_Name: Geodetic Reference System 80

Semi-major_Axis: 6378137.000000

Denominator_of_Flattening_Ratio: 298.257222

Vertical_Coordinate_System_Definition:

Altitude_System_Definition:

Altitude_Resolution: 0.000122

Altitude_Encoding_Method:

Explicit elevation coordinate included with horizontal coordinates

Entity_and_Attribute_Information:

Detailed_Description:

Entity_Type:

Entity_Type_Label: ClwLandtype_20121207

Attribute:

Attribute_Label: LTA_Dscrpt

Attribute_Definition:

Description of landtype association - See Interpretations in Purpose

Attribute_Definition_Source: Clearwater National Forest

Attribute_Domain_Values:

Unrepresentable_Domain:

Sequential unique whole numbers that are automatically generated.

Attribute:

Attribute_Label: FireRegime

Attribute_Definition: Fire regime class - See Interpretations in Purpose

Attribute_Definition_Source: Clearwater National Forest

Attribute_Domain_Values:

Unrepresentable_Domain:

Sequential unique whole numbers that are automatically generated.

Attribute:

Attribute_Label: 2ndFrRegim

Attribute_Definition: Secondary fire regime class - See Interpretations in Purpose

Attribute_Definition_Source: Clearwater National Forest

Attribute_Domain_Values:

Unrepresentable_Domain:

Sequential unique whole numbers that are automatically generated.

Attribute:

Attribute_Label: FrRgmCls

Attribute_Definition: Fire Regime Class - See Interpretations in Purpose

Attribute_Definition_Source: Clearwater National Forest

Attribute_Domain_Values:

Unrepresentable_Domain:

Sequential unique whole numbers that are automatically generated.

Attribute:

Attribute_Label: HAZ_RATING

Attribute_Definition: Hazard Rating - - See Interpretations in Purpose

Attribute_Definition_Source: Clearwater National Forest

Attribute_Domain_Values:

Unrepresentable_Domain:

Sequential unique whole numbers that are automatically generated.

Attribute:

Attribute_Label: FACTS_FIRE

Attribute_Definition: FACTS Fire Regime Group - used in FACTS reporting

Attribute_Definition_Source: Clearwater National Forest

Attribute_Domain_Values:

Unrepresentable_Domain:

Sequential unique whole numbers that are automatically generated.

Attribute:

Attribute_Label: BURN_CLASS

Attribute_Definition:

Burning class designed to provide recommendations for prescribed burning on the landtype. See Purpose section, Interpretations for more information.

Attribute_Definition_Source: Clearwater National Forest

Attribute_Domain_Values:

Unrepresentable_Domain:

Sequential unique whole numbers that are automatically generated.

Attribute:

Attribute_Label: LANDTYPE

Attribute_Definition: Landtype

Attribute_Definition_Source: Clearwater National Forest

Attribute:

Attribute_Label: ACRES

Attribute_Definition: Area within polygon expressed in acres

Attribute_Definition_Source: Clearwater National Forest

Attribute:

Attribute_Label: LTA

Attribute_Definition: Landtype Association

Attribute_Definition_Source: Clearwater National Forest

Attribute_Domain_Values:

Unrepresentable_Domain: Positive real numbers that are automatically generated.

Attribute:

Attribute_Label: LTA_GROUP

Attribute_Definition: Landtype Association Group

Attribute_Definition_Source: Clearwater National Forest

Attribute:

Attribute_Label: Descript

Attribute_Definition: Description of the physical features of the landtype

Attribute_Definition_Source: Clearwater National Forest

Attribute:

Attribute_Label: GROUPNUM

Attribute_Definition: Field identical to LTA Group

Attribute_Definition_Source: Clearwater National Forest

Attribute_Domain_Values:

Unrepresentable_Domain: Positive real numbers that are automatically generated.

Attribute:

Attribute_Label: acres

Attribute_Definition: Area within polygon expressed in acres

Attribute_Definition_Source: Clearwater National Forest

Attribute_Domain_Values:

Unrepresentable_Domain: Coordinates defining the features.

Attribute:

Attribute_Label: MASS_WASTE

Attribute_Definition: Mass wasting potential - - See Interpretations in Purpose

Attribute_Definition_Source: Clearwater National Forest

Attribute:

Attribute_Label: SurfErosn

Attribute_Definition: Surface Erosion Potential - - See Interpretations in Purpose

Attribute_Definition_Source: Clearwater National Forest

Attribute:

Attribute_Label: SubSrfErsn

Attribute_Definition: Sub-surface erosion potential

Attribute_Definition_Source: Clearwater National Forest

Attribute:

Attribute_Label: DEBRIS_AVA

Attribute_Definition:

Debris avalanche mass wasting potential - - See Interpretations in Purpose

Attribute_Definition_Source: Clearwater National Forest

Attribute:

Attribute_Label: SedDelEff

Attribute_Definition: Slope sediment delivery efficiency

Attribute_Definition_Source: Clearwater National Forest

Attribute:

Attribute_Label: PARENT_MAT

Attribute_Definition: Parent material types - See Interpretations in Purpose

Attribute_Definition_Source: Clearwater National Forest

Attribute_Domain_Values:

Unrepresentable_Domain: Coordinates defining the features.

Attribute:

Attribute_Label: RdCstrCost

Attribute_Definition: Road Construction Cost Class - See Interpretations in Purpose

Attribute_Definition_Source: Clearwater National Forest

Attribute:

Attribute_Label: TraffCls

Attribute_Definition: Trafficability class - See Interpretations in Purpose

Attribute_Definition_Source: Clearwater National Forest

Attribute_Domain_Values:

Unrepresentable_Domain: Coordinates defining the features.

Attribute:

Attribute_Label: Shape

Attribute_Definition: Feature geometry.

Attribute_Definition_Source: ESRI

Attribute_Domain_Values:

Unrepresentable_Domain: Coordinates defining the features.

Attribute:

Attribute_Label: ROAD_MAINT

Attribute_Definition: Road maintenance factors - See Interpretations in Purpose

Attribute_Definition_Source: Clearwater National Forest

Attribute:

Attribute_Label: UNIF_SOIL

Attribute_Definition: Unified Soil Classification - See Interpretations in Purpose

Attribute_Definition_Source: Clearwater National Forest

Attribute:

Attribute_Label: SoilPrdCls

Attribute_Definition: Soil productivity class - See Interpretations in Purpose

Attribute_Definition_Source: Clearwater National Forest

Attribute:

Attribute_Label: RegenLimit

Attribute_Definition: Regeneration Limit - See Interpretations in Purpose

Attribute_Definition_Source: Clearwater National Forest

Attribute:

Attribute_Label: SoilSnsCls

Attribute_Definition:

Soil Sensitivity to Disturbance - See Interpretations in Purpose

Attribute_Definition_Source: Clearwater National Forest

Attribute:

Attribute_Label: ROAD_SUIT

Attribute_Definition: Roading suitability class - See Interpretations in Purpose

Attribute_Definition_Source: Clearwater National Forest

Attribute:

Attribute_Label: RIP_CLASS

Attribute_Definition: Rippability class - See Interpretations in Purpose

Attribute_Definition_Source: Clearwater National Forest

Attribute:

Attribute_Label: LogMethCls

Attribute_Definition: Logging method class - See Interpretations in Purpose

Attribute_Definition_Source: Clearwater National Forest

Attribute:

Attribute_Label: FireErsn

Attribute_Definition: Fire erosion risk - See Interpretations in Purpose

Attribute_Definition_Source: Clearwater National Forest

Attribute:

Attribute_Label: WIND_THROW

Attribute_Definition: Windthrow susceptibility class - See Interpretations in Purpose

Attribute_Definition_Source: Clearwater National Forest

Attribute:

Attribute_Label: PrntMtErsn

Attribute_Definition:

Parent material erosion potential - See Interpretations in Purpose

Attribute_Definition_Source: Clearwater National Forest

Overview_Description:

Distribution_Information:

Distributor:

Contact_Information:

Contact_Organization_Primary:

Contact_Organization: Clearwater National Forest

Resource_Description: Downloadable Data

Standard_Order_Process:

Digital_Form:

Digital_Transfer_Information:

Transfer_Size: 0.121

Metadata_Reference_Information:

Metadata_Date: 20121207

Metadata_Contact:

Contact_Information:

Contact_Organization_Primary:

Contact_Organization: USDA Forest Service - Clearwater National Forest

Contact_Person:

Contact_Position:

Contact_Address:

Address_Type: mailing address

Address: 12730 Hwy 12

City: Orofino

State_or_Province: ID

Postal_Code: 83544

Country: USA

Contact_Voice_Telephone: 208-476-4541

Metadata_Standard_Name: FGDC Content Standards for Digital Geospatial Metadata

Metadata_Standard_Version: FGDC-STD-001-1998

Metadata_Time_Convention: local time

Metadata_Extensions:

Online_Linkage: <http://www.esri.com/metadata/esriprof80.html>

Profile_Name: ESRI Metadata Profile

Metadata_Extensions:

Online_Linkage: <http://www.esri.com/metadata/esriprof80.html>

Profile_Name: ESRI Metadata Profile

Metadata_Extensions:

Online_Linkage: <http://www.esri.com/metadata/esriprof80.html>

Profile_Name: ESRI Metadata Profile

Metadata_Extensions:

Online_Linkage: <http://www.esri.com/metadata/esriprof80.html>

Profile_Name: ESRI Metadata Profile

Metadata_Extensions:

Online_Linkage: <http://www.esri.com/metadata/esriprof80.html>

Profile_Name: ESRI Metadata Profile