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Draft. A draft ecological site description is either incomplete or has not undergone quality control and quality assurance review.
MLRA notes
Major Land Resource Area (MLRA): 035X–Colorado Plateau
AZ CRA 35.5 – Grand Canyon Corridor
Elevations range from 1600 to 4500 feet and precipitation averages 6 to 10 inches per year. Extreme elevation and aspect changes make this area unique. Vegetation includes Mormon tea, catclaw, white brittlebush, blackbrush, prickly pear, cholla species, big galleta, and blue threeawn. The soil temperature regime ranges from thermic to mesic and the soil moisture regime is typic aridic. This unit occurs within the Colorado Plateau Physiographic Province and is characterized by extreme vertical escarpments and strong aspect differences over short distances. Sedimentary rock classes dominate the Grand Canyon and exposures consist of a thick sequence of relatively undeformed formations.Associated sites
R035XE502AZ Channery Hills 6-10" p.z.
Channery Hills 6-10" p.z. Areas of mudstone/siltstone, often on top of the schist.
R035XE516AZ Sedimentary Cliffs 6-10" p.z.
Sedimentary Cliff 6-10" p.z. Areas of intermixing of sedimentary cliff-forming formations
R035XE519AZ Limy Upland 6-10" p.z. Shallow
Limy Upland 6-10" p.z. Level to gently sloping sedimetry formations such as Tapeats Sandstone that sit on top of the schist and granite formations.
Table 1. Dominant plant species
Tree Not specified
Shrub (1) Encelia farinosa
(2) Ephedra viridisHerbaceous (1) Pleuraphis rigida
(2) Muhlenbergia porteriPhysiographic features
This ecological site is found on pockets and ledges of steep to nearly vertical formations of Vishnu Schist and Zoroaster Granite. Soils are very shallow and shallow with a great deal of rock outcrop and occurs on all aspects. The plant communities are significantly influenced by the strong relief and aspect changes. Slopes are typically 15-60%, but can be much higher. Eolian sand deposits from 1/2-3 inches in depth, especially in the wind corridors, are an important influence.
Table 2. Representative physiographic features
Landforms (1) Hill
(2) Mountain
(3) Mountain slope
Flooding frequency None Ponding frequency None Elevation 1600 – 4600 ft Slope 15 – 60 % Aspect Aspect is not a significant factor Climatic features
The climate of the land resource unit is arid to semiarid with warm summers and cool winters. The mean annual precipitation ranges from 6 – 10 inches, but it is very erratic, often varying substantially from year to year. The majority of the precipitation falls during the between October through May. This precipitation comes as gentile rain or occasionally snow from frontal storms coming out to the Pacific Ocean. Snow is infrequent and rarely last more than 1-2 days. The remaining precipitation comes from July through September as spotty, unreliable and sometimes violent thunderstorms. The moisture for this precipitation originates in the Gulf of Mexico (and the Pacific Ocean in the fall) and flows into the area on the north end of the Mexican monsoon. Late May through late June is generally a dry period. The mean annual air temperature ranges from 55 to 69 degrees Fahrenheit (F). The frost-free period (air temperature > 32 degrees F) ranges from 180 to 220 days (@ 50 percent probability).
Table 3 Representative climatic features
Frost-free period (average) 200 days Freeze-free period (average) 220 days Precipitation total (average) 10 in BarLineFigure 1. Monthly precipitation range
BarLineFigure 2. Monthly average minimum and maximum temperature
">Influencing water features
Soil features
Soil surface textures are sandy loams to very fine sandy loams, and are typically gravelly to very stony and very cobbly. Soil depth is shallow to very shallow with pockets of deep soil in some places and skree slopes in others. The surface is lightly effervescent uually, and strongly effervescent at times.
Soil temperature regime is thermic; moisture regime is typic aridic. Erosion hazards are moderate for water, low for wind.
Soils mapped on this site include:
SSA-701 Grand Canyon Area MU's 101 Akela family and 110 Lithic torriorthents.
Soil diagnostic horizon is lithc contact; restrictive layer is bedrock (lithic). Soils are very shallow to shallow, moderatey alkaline (7.9-8.4), with slight to strong effervescence.
Geologic formation is Vishnu schist.
Soil survey correlation:
AZ701, Grand Canyon Area 101 (Akel family), 629 (Hulda family) , and 829 (Lithic Toriorthents.Table 4. Representative soil features
Parent material (1) Colluvium – schist
(2) Colluvium – granite
(3) Eolian deposits – limestone and sandstone
Surface texture (1) Very stony very fine sandy loam
(2) Very cobbly fine sandy loam
(3) Sandy loam
Family particle size (1) Loamy
Drainage class Well drained Permeability class Moderately rapid Soil depth 8 – 20 in Surface fragment cover <=3" 0 – 15 % Surface fragment cover >3" 0 – 30 % Available water capacity
(0-40in)0 – 2.5 in Calcium carbonate equivalent
(0-40in)0 – 15 % Electrical conductivity
(0-40in)0 – 2 mmhos/cm Sodium adsorption ratio
(0-40in)0 – 2 Soil reaction (1:1 water)
(0-40in)7.9 – 8.4 Subsurface fragment volume <=3"
(Depth not specified)0 – 20 % Subsurface fragment volume >3"
(Depth not specified)0 – 30 % Ecological dynamics
The plant communities found on an ecological site are naturally variable. Composition and production will vary with yearly conditions, location, aspect, and the natural variability of the soils. The historical climax plant community represents the natural potential plant communities found on relict or relatively undisturbed sites. Other plant communities described here represent plant communities that are known to occur when the site is disturbed by factors such as grazing, fire, or drought.
Production data provided in this site description is standardized to air-dry weight at the end of the summer growing season. The plant communities described in this site description are based on near normal rainfall years.
NRCS uses a Similarity Index to compare existing plant communities to the plant communities described here. Similarity Index is determined by comparing the production and composition of a plant community to the production and composition of a plant community described in this site description. To determine Similarity Index, compare the production (air-dry weight) of each species to that shown in the plant community description. For each species, count no more than the maximum amount shown for the species, and for each group, count no more than the maximum shown for the group. Divide the resulting total by the total normal year production shown in the plant community description. If rainfall has been significantly above or below normal, use the total production shown for above or below normal years. If field data is not collected at the end of the summer growing season, then the field data must be corrected to the end of the year production before comparing it to the site description. The growth curve can be used as a guide for estimating production at the end of the summer growing season.
State and transition model
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Click on state and transition labels to scroll to the respective textEcosystem states
State 1 submodel, plant communities
State 1
Historic Climax Plant CommunityCommunity 1.1
Historic Climax Plant CommunityThis community has a substantial shrub component that varies with aspect and the presense or absence of eolian sand. Exposed slopes can be extremely hot and dominated by white brittlebush; cooler slopes are dominated by ephedras with a larger compoent of grasses. Areas with an eolian sand inflence have significantly more warm and cool season grasses (annual and perennial) than do areas with no sand influence.
Figure 3. Annual production by plant type (representative values) or group (midpoint values)
Table 5. Annual production by plant type
Plant type Low
(lb/acre)Representative value
(lb/acre)High
(lb/acre)Shrub/Vine 175 250 280 Grass/Grasslike 20 60 90 Forb 20 40 55 Total 215 350 425 Additional community tables
Table 6. Community 1.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Grass/Grasslike1 Dominant Native Perennial Summer Mid Grasses 5–35 black grama BOER4 Bouteloua eriopoda 5–18 – bush muhly MUPO2 Muhlenbergia porteri 5–18 – big galleta PLRI3 Pleuraphis rigida 5–18 – 2 Occasional Native Perennial Summer Mid Grasses 5–20 Grass, perennial 2GP Grass, perennial 0–25 – sideoats grama BOCU Bouteloua curtipendula 0–25 – spike dropseed SPCO4 Sporobolus contractus 0–25 – sand dropseed SPCR Sporobolus cryptandrus 0–25 – mesa dropseed SPFL2 Sporobolus flexuosus 0–25 – 3 Occasional Native Perennial Summer Short Grasses 5–10 Grass, perennial 2GP Grass, perennial 0–5 – slender spiderling BOTR Boerhavia triquetra 0–5 – low woollygrass DAPU7 Dasyochloa pulchella 0–5 – nineawn pappusgrass ENDE Enneapogon desvauxii 0–5 – 4 Common Native Perennial Spring Mid Grasses 5–20 purple threeawn ARPU9 Aristida purpurea 0–10 – blue threeawn ARPUN Aristida purpurea var. nealleyi 0–10 – 5 Occasional Native Perennial Spring Mid Grasses 0–10 Grass, perennial 2GP Grass, perennial 0–5 – desert needlegrass ACSP12 Achnatherum speciosum 0–3 – squirreltail ELELE Elymus elymoides ssp. elymoides 0–2 – slim tridens TRMU Tridens muticus 0–2 – 6 Native Annual Grasses 5–35 Grass, annual 2GA Grass, annual 0–15 – sixweeks threeawn ARAD Aristida adscensionis 0–15 – sixweeks grama BOBA2 Bouteloua barbata 0–15 – muhly MUHLE Muhlenbergia 0–15 – panicgrass PANIC Panicum 0–15 – sixweeks fescue VUOC Vulpia octoflora 0–15 – Forb7 Common Native Perennial Spring Forbs 5–20 Forb, perennial 2FP Forb, perennial 0–4 – brownfoot ACWR5 Acourtia wrightii 0–4 – bluestar AMSON Amsonia 0–4 – lipfern CHEIL Cheilanthes 0–4 – desert trumpet ERIN4 Eriogonum inflatum 0–4 – desert stingbush EUUR Eucnide urens 0–4 – pepperweed LEPID Lepidium 0–4 – rose bladderpod LEPU2 Lesquerella purpurea 0–4 – roving sailor MAAN9 Maurandella antirrhiniflora 0–4 – spiny phlox PHHO Phlox hoodii 0–4 – spikemoss SELAG Selaginella 0–4 – globemallow SPHAE Sphaeralcea 0–4 – 8 Common Native Perennial Summer Forbs 5–10 Forb, perennial 2FP Forb, perennial 0–5 – Indian mallow ABUTI Abutilon 0–5 – trailing windmills ALIN Allionia incarnata 0–5 – tansyaster MACHA Machaeranthera 0–5 – brownplume wirelettuce STPA4 Stephanomeria pauciflora 0–5 – 9 Common Native Annual Forbs 5–35 Forb, annual 2FA Forb, annual 0–7 – cryptantha CRYPT Cryptantha 0–7 – sacred thorn-apple DAWR2 Datura wrightii 0–7 – spurge EUPHO Euphorbia 0–7 – shaggyfruit pepperweed LELA Lepidium lasiocarpum 0–7 – desertdandelion MALAC3 Malacothrix 0–7 – whitestem blazingstar MEAL6 Mentzelia albicaulis 0–7 – desert tobacco NIOB Nicotiana obtusifolia 0–7 – phacelia PHACE Phacelia 0–7 – groundcherry PHYSA Physalis 0–7 – popcornflower PLAGI Plagiobothrys 0–7 – desert Indianwheat PLOV Plantago ovata 0–7 – woolly tidestromia TILA2 Tidestromia lanuginosa 0–7 – Shrub/Vine10 Common Native Half Shrubs 20–35 broom snakeweed GUSA2 Gutierrezia sarothrae 5–10 – slender poreleaf POGR5 Porophyllum gracile 5–10 – Mojave woodyaster XYTO2 Xylorhiza tortifolia 5–10 – pricklyleaf dogweed THAC Thymophylla acerosa 0–5 – turpentinebroom THMO Thamnosma montana 0–5 – Parish's goldeneye VIPA14 Viguiera parishii 0–5 – mountain phlox PHAU3 Phlox austromontana 0–5 – Shrub, other 2S Shrub, other 0–5 – white sagebrush ARLU Artemisia ludoviciana 0–5 – starry bedstraw GAST Galium stellatum 0–5 – 11 Dominant Native Shrubs 100–210 brittlebush ENFA Encelia farinosa 20–100 – Nevada jointfir EPNE Ephedra nevadensis 5–50 – mormon tea EPVI Ephedra viridis 5–50 – catclaw acacia ACGR Acacia greggii 5–35 – 12 Occasional Native Shrubs 0–10 Shrub, other 2S Shrub, other 0–10 – Wright's beebrush ALWR Aloysia wrightii 0–10 – shortleaf baccharis BABR Baccharis brachyphylla 0–10 – sweetbush BEJU Bebbia juncea 0–10 – mouse's eye BEMY Bernardia myricifolia 0–10 – spearleaf brickellbush BRAT Brickellia atractyloides 0–10 – California brickellbush BRCA3 Brickellia californica 0–10 – water jacket LYAN Lycium andersonii 0–10 – Schott's pygmycedar PESC4 Peucephyllum schottii 0–10 – American threefold TRCA8 Trixis californica 0–10 – 13 Common Native Cacti 0–10 Whipple cholla CYWH Cylindropuntia whipplei 0–10 – Engelmann's hedgehog cactus ECEN Echinocereus engelmannii 0–10 – cottontop cactus ECPO2 Echinocactus polycephalus 0–10 – California barrel cactus FECY Ferocactus cylindraceus 0–10 – Graham's nipple cactus MAGR9 Mammillaria grahamii 0–10 – beavertail pricklypear OPBA2 Opuntia basilaris 0–10 – dollarjoint pricklypear OPCH Opuntia chlorotica 0–10 – cactus apple OPEN3 Opuntia engelmannii 0–10 – plains pricklypear OPPO Opuntia polyacantha 0–10 – grizzlybear pricklypear OPPOE Opuntia polyacantha var. erinacea 0–10 – 14 Occasional Native Agave-Yucca-Like 0–5 Utah agave AGUT Agave utahensis 0–2 – Kaibab agave AGUTK Agave utahensis var. kaibabensis 0–2 – banana yucca YUBA Yucca baccata 0–2 – soaptree yucca YUEL Yucca elata 0–2 – Interpretations
Supporting information
Contributors
Art Meen
Rangeland health reference sheet
Interpreting Indicators of Rangeland Health is a qualitative assessment protocol used to determine ecosystem condition based on benchmark characteristics described in the Reference Sheet. A suite of 17 (or more) indicators are typically considered in an assessment. The ecological site(s) representative of an assessment location must be known prior to applying the protocol and must be verified based on soils and climate. Current plant community cannot be used to identify the ecological site.
Author(s)/participant(s) Contact for lead author Date Approved by Approval date Composition (Indicators 10 and 12) based on Annual Production Indicators
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Number and extent of rills:
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Presence of water flow patterns:
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Number and height of erosional pedestals or terracettes:
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Bare ground from Ecological Site Description or other studies (rock, litter, lichen, moss, plant canopy are not bare ground):
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Number of gullies and erosion associated with gullies:
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Extent of wind scoured, blowouts and/or depositional areas:
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Amount of litter movement (describe size and distance expected to travel):
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Soil surface (top few mm) resistance to erosion (stability values are averages - most sites will show a range of values):
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Soil surface structure and SOM content (include type of structure and A-horizon color and thickness):
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Effect of community phase composition (relative proportion of different functional groups) and spatial distribution on infiltration and runoff:
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Presence and thickness of compaction layer (usually none; describe soil profile features which may be mistaken for compaction on this site):
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Functional/Structural Groups (list in order of descending dominance by above-ground annual-production or live foliar cover using symbols: >>, >, = to indicate much greater than, greater than, and equal to):
Dominant:
Sub-dominant:
Other:
Additional:
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Amount of plant mortality and decadence (include which functional groups are expected to show mortality or decadence):
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Average percent litter cover (%) and depth ( in):
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Expected annual annual-production (this is TOTAL above-ground annual-production, not just forage annual-production):
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Potential invasive (including noxious) species (native and non-native). List species which BOTH characterize degraded states and have the potential to become a dominant or co-dominant species on the ecological site if their future establishment and growth is not actively controlled by management interventions. Species that become dominant for only one to several years (e.g., short-term response to drought or wildfire) are not invasive plants. Note that unlike other indicators, we are describing what is NOT expected in the reference state for the ecological site:
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Perennial plant reproductive capability:
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