Range Capability Process on Strawberry Peak Allotment

Transcription

1 Range Capability Process on Strawberry Peak Allotment Capability on the Ashley National Forest was largely determined for the current 1986 Forest Plan and beginning around the 1960s using a data collection and inventory method called Range Analysis and verified over the years by long-term monitoring studies. Part of the Range Analysis process was to identify rangelands capable of supporting livestock. Range capability was historically referred to as suitability. Range suitability in 1983 was defined as, Land that is accessible, or that can be made accessible to livestock, which produces forage or has inherent forage producing capabilities and that can be grazed on a sustained yield basis under reasonable management goals. This definition for suitability is what the U.S. Forest Service currently refers to as capability (Forest Service 2016). To avoid further confusion, in this document, capability will be used in place of what was historically called suitability in the Ashley s Range Analysis inventory. The 1983 Region 4 Range Analysis Handbook stated that, Range analysis is a program concerned with the systematic collection and evaluation of range resource and soils data. It consists of identifying and mapping vegetative types and the plant species within these types, suitability (i.e., capability) for grazing by livestock, and the ecological condition of the range. It provides for the periodic measurement of trend and the monitoring of condition. It further provides for the collection of essential information for range improvements, range readiness, and season of use for livestock management. This information is used in planning and in making management decisions. Range Analysis was a field mapping project to map: Vegetation Types Range Capability Range Condition Apparent trend for vegetation and soil stability The mapping process consisted of delineating vegetation types in the field on aerial photos. Once a vegetation type was mapped, transects were established in these vegetation type polygons to collect data. Generally about three transects were established in one vegetation type polygon. Forage production, vegetation, and soil data were collected at each transect. Forage production data were collected by clipping vegetation by species at 10 plots per transect for a total of 30 plots per polygon. Forage production was summarized by species on Site Analysis Forms according to the species desirability rating. Species were rated as desirable, intermediate, and least desirable. Species that were rated as desirable and intermediate, mostly grasses, were used to determine forage production. Soil condition data were collected at each transect to determine the potential for soil erodibility. These data consisted of soil type, soil texture, soil thickness, ground cover, dispersion of ground cover, and current erosion status. These data were ultimately used in indices that determined the status of ground cover and current erosion that will be described below. Slope and topography data were also collected at each transect. A determination of livestock accessibility such as, the presence of rock slides, boulder fields, cliffs or other obstructions that may 1

2 prohibit access by livestock was also made as well as the distance of a vegetation type polygon from water. The Ashley National Forest used the Range Analysis field data, summaries, classification, and mapping to determine range capability on the Strawberry Peak Allotment. As described above, the Range Analysis process used physical, soil, and vegetative characteristics to determine the capability of rangelands. The following criteria were used to determine the capability of rangelands. 1. Forage Productivity 2. Soil Condition a. Soil Erodibility b. Topography c. Ground Cover d. Dispersion of Ground Cover 3. Current Erosion 4. Accessibility 5. Slope 6. Distance from water Vegetation type (Table 1) polygons or sites were considered capable if the collected forage was greater than 50lbs/acre dry weight, soil conditions were generally greater than or equal to 40 points as determined by adding the points determined through the Ground Cover and Current Erosion indices (Tables 2 and 3), accessibility was adequate as assessed in the field, and distance from water was 1 mile (Table 4). Table 1. Vegetation Types Vegetation Type # Vegetation Type 1 Grassland 2w Wet Meadow 2d Dry Meadow 3 Perennial Forbs 4 Sagebrush 5 Browse Shrub 6 Conifer 7T Heavy Timber 8 Barren 9 Pinyon-Juniper 10 Broadleaf Trees 11 Creosote 12 Mesquite 13 Saltbush 14 Greasewood 15 Winterfat 16 Desert Shrub 17 Half Shrub 18 Annuals 20 Successful Cultural Treatment 2

3 Table 2. Ground Cover Index Points Ground Cover 1 Cover Dispersion Classification % Uniform % Uniform % Fairly Uniform % Variable % Highly Variable 1 Ground Cover Basal area of herbaceous plants, moss and lichens, litter, and pavement rock ¾ inch in diameter. Difference between 2nd highest and 2nd lowest plots Table 3. Current Erosion Index Points Description Summary Brief Description No evidence of Soil movement Plant and litter cover adequate for soil protection and well dispersed Soil movement slight and local Isolated bare soil openings Soil movement moderate Bare soil openings larger and frequently joined together Soil movement advanced Bare ground dominates the site Soil movement severe Most of the area bare and uninfluenced by vegetation and litter. 1 Full description described in USDA Forest Service Table 4. Criteria for Capable Rangelands on the Strawberry Allotment Criteria Standard for Capability Criteria Forage Production > 50lbs/acre Soil Condition/Current Erosion Cumulative score of 40 1 Accessibility Polygon is absent of rock slides, boulder fields, cliffs or other obstructions. Slope 30% (Cattle) Distance from Water 1 mile 1 Score may be < 40 if the soil does not have the inherent capability to produce 60% 70% ground cover, provided there are no other adverse site factors. The Range Analysis protocol allowed some variance on the soil condition score when rating a vegetation type polygon as capable or not capable based on certain factors observed at the site. These factors included steepness of slope, roughness of slope, slope length, distributional habits of livestock, site potential, multiple use constraints, and an adjoining site with similar characteristics (USDA Forest Service 1983). The protocol also allowed a site to be classified as capable if areas with low ground cover could be restored under a reasonable system of management or if the erosion of an area could be arrested and stability restored under an attainable management system. These considerations were based on the inherent capability of a soil or its state of deterioration. Consideration of soil condition also included the inherent capability of a soil to support a certain percentage of ground cover or ground cover dispersion as described in the Table 1. Ground Cover Index. For example, sites with uniform ground cover dispersion and low ground cover may have had greater 3

4 stability than areas with higher ground cover but with variable dispersion. Both the amount of ground cover and the dispersion of ground cover were considered at the site in the field when classifying a vegetation type polygon as capable. On the Strawberry Allotment there were a total of six polygons that had a soil condition rating of less than 40 for a total of 624 acres. As stated above, the Range Analysis protocol allowed a site to be classified as capable if areas with low ground cover could be restored under a reasonable system of management or if the erosion of an area could be arrested and stability restored. These six polygons were identified as capable in the original analysis because the examiner determined that low ground cover could be restored or erosion arrested under the existing management system. Areas of four of the six vegetation type polygons were visited by a soils scientist to evaluate current conditions between 2013 and At these sites ground cover was greater than or equal to 70% and soil movement characteristics were moderate or better (Table 5). Table 5. Current soil evaluations of vegetation type polygons with a soil condition rating < 40. Field Range Quadrangle Information from Field Reviews ( ) Stop Map Section Number Region 4 Soil Condition Evaluation Form Used Number Listing Section 36 Section 31 S S Most grass on slight pedestals. Ground cover 95% with 70% gravel component. Bare soil 5%. Litter well distributed under shrubs but low in interspaces. Field stop noted inherent conditions limiting vegetation production: windswept ridge summit, 70% surface rock, and shallow soil. These factors limit available water and nutrients available for supporting forage. Few pedestalled grasses. Ground cover 95% with 90% gravel component. Bare soil 5%. Litter minimal and not well distributed. Field stop noted inherent conditions limiting vegetation production: windswept ridge summit, 90% surface rock, and shallow soil. These factors limit available water and nutrients available for supporting forage. Pedestalling was noted to be present but not common. 4

5 Strawberry Peak Section 36 S Few pedestalled grasses and sheet wash in interspaces. Ground cover 86% with 33% litter and flattened grasses. Bare soil 14%. Litter well distributed. Slight sheet wash in interspaces between shrubs. Ground cover 87% with 26% litter and flattened grasses. Bare soil 13%. Litter well distributed. Field stop rated unsatisfactory soil conditions at microsite of corral. Not detailed stop: photo records taken. Compaction footprint of the corral and area around it that leaves estimated 2 acre area with compacted soil, and no to low vegetation. Accelerated erosion was limited by flat terrain but sheet wash present. Ground cover very low to absent within 2 acre footprint. Bare soil very high- no ocular estimate. Litter absent in footprint area. Compaction along old road and in trailing. Slight sheet wash in trailing area. Ground cover 80% with 37% rock cover. Bare soil 20%. Litter not well distributed. Field stop rated impaired soil conditions: Not detailed stop. Microsite on concave slope position. Compaction from former road and current trailing. Erosion noted from inherent shale and mudstone as well as impacts. Ground cover 93% with high cover of surface rock giving stability. 5

6 Strawberry Peak Section 25 S Bare soil 7%. Litter very low and not well distributed. Minor sheet wash. Ground cover 88% with 60% shrub and grass cover. Bare soil 12%. Litter well distributed. Compaction in trailing areas. No pedestalling. Ground cover 70% with 65% shrub and grass cover. Bare soil 30%. Litter low and not well distributed. Adjacent area had inherent conditions of very shallow soil over bedrock and high surface rock (gravel) cover corresponding with low vegetation productivity. Most grass pedestalled. Deposition with many debris dams. Ground cover 70% with 25% litter and veg. basal. Bare soil 30% Road noted to be channeling water noted in area and bare area of road starting to revegetate. No compaction found. The Range Analysis considered areas with a potential to produce greater than 50 pounds of forage per acre dry weight as capable. The current accepted opinion is that this value should be 200 pounds of forage per acre dry weight. Although vegetation type polygons on the Strawberry Allotment were classified as capable based on 50 pounds of forage per acre, data from the range analysis evaluation show that the vegetation type polygons classified as capable all produced more than 200 pounds of forage per acre (Table 6). 6

7 Table 6. Capable vegetation type polygons on the Strawberry Allotment and forage production. Map Capability Classification Forage Production lbs/acre of Desirables 1 & Intermediates 2 Acres S S S S S S S S S S S S S S S S S S S S S S

8 54 S S S S S S S S S S S S S S Totals 3,527 1 Desirables These are species common to pristine plant communities. They are usually good forage plants and generally are first to show adverse effects of excessive grazing use. The species are generally good soil binders, especially in natural mixtures of desirable species (USDA Forest Service 1983, 2.32a). 2 Intermediates These are species common to the pristine plant community, but which are not as adversely affected by grazing use as are the Desirables. They may be less palatable to grazing animals or be more resistant to grazing use. As a result, the either hold their own in the stand or they may increase in proportion to other species or even replace the most desirable species that are list or reduced as a result of selective grazing use (USDA Forest Service 1983, 2.32a). 3 Missing data sheets from the 1964 site analysis. 8

9 Legend: S # = X/Y = Capable Acres N # = X/Y = Not Capable Acres # = Vegetation Type X = Condition Rating for Vegetation Y = Condition Rating for Soil Miles ± The attached map shows the vegetation type polygons that were classified in the field as capable for cattle. These capable polygons can be identified on the map by an S for suitable/capable and a vegetation type number (e.g., S4). 9

10 Literature Cited USDA Forest Service Region 4 Range Analysis Handbook. FSH Ogden, UT. (see pgs. 2.41c-1, 2.31c-2, and 2.32a). USDA Forest Service Site Analysis R (11/68 and 8/81) User Guide, Ashley National Forest S. Goodrich Unpublished report on file at: U.S. Department of Agriculture, Forest Service, Ashley National Forest. 15 pp. USDA Forest Service History of Capability and Suitability in Region 4 and on the Ashley National Forest. Unpublished report on file at: U.S. Department of Agriculture, Forest Service, Ashley National Forest. 10