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Provisional. A provisional ecological site description has undergone quality control and quality assurance review. It contains a working state and transition model and enough information to identify the ecological site.
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Figure 1. Mapped extent
Areas shown in blue indicate the maximum mapped extent of this ecological site. Other ecological sites likely occur within the highlighted areas. It is also possible for this ecological site to occur outside of highlighted areas if detailed soil survey has not been completed or recently updated.
MLRA notes
Major Land Resource Area (MLRA): 041X–Madrean Archipelago
AZ 41.3 – Chihuahuan – Sonoran Semidesert Grasslands
Elevations range from 3200 to 5000 feet and precipitation ranges from 12 to 16 inches per year. Vegetation includes mesquite, catclaw acacia, netleaf hackberry, palo verde, false mesquite, range ratany, fourwing saltbush, tarbush, littleleaf sumac, sideoats grama, black grama, plains lovegrass, cane beardgrass, tobosa, vine mesquite, threeawns, Arizona cottontop and bush muhly. The soil temperature regime is thermic and the soil moisture regime is ustic aridic. This unit occurs within the Basin and Range Physiographic Province and is characterized by numerous mountain ranges that rise abruptly from broad, plain-like valleys and basins. Igneous and metamorphic rock classes dominate the mountain ranges and sediments filling the basins represent combinations of fluvial, lacustrine, colluvial and alluvial deposits.Table 1. Dominant plant species
Tree Not specified
Shrub Not specified
Herbaceous Not specified
Physiographic features
This site occurs on hillslopes and ridgetops. Slope aspect is site differentiating at elevations near land resource area boundaries.
Table 2. Representative physiographic features
Landforms (1) Hill
(2) Ridge
Flooding frequency None Ponding frequency None Elevation 1158 – 1676 m Slope 15 – 70 % Climatic features
Precipitation in this common resource area ranges from 12-16 inches yearly in the eastern part with elevations from 3600-5000 feet, and 13-17 inches in the western part where elevations are 3300-4500 feet. Winter-Summer rainfall ratios are 40-60% in the west and 30-70% in the east. Summer rains fall July-September, originate in the Gulf of Mexico and are convective, usually brief, intense thunderstorms. Cool season moisture tends to be frontal, originate in the Pacific and Gulf of California, and falls in widespread storms with long durarion and low density. Snow rarely lasts more than one day. May and June are the driest months of the year. Humidity is generally very low.
Temperatures are mild. Freezing temperatures are common at night from December-April; however temperatures during the day are frequently above 50 F. Occasionally in December-February, brief 0 F temperatures may be experienced some nights. During June, July and August, some days may exceed 100 F.
Cool season plants start growth in early spring and mature in early summer. Warm season plants take advantage of summer rains and are growing and nutritions July-September. Warm season grasses may remain green throughout the year.Table 3 Representative climatic features
Frost-free period (average) 220 days Freeze-free period (average) 0 days Precipitation total (average) 410 mm BarLineFigure 2. Monthly precipitation range
BarLineFigure 3. Monthly average minimum and maximum temperature
">Influencing water features
Soil features
These are shallow soils formed in slope alluvium of mixed basic igneous and cargonatic minerology. Soils are calcareous loams and clay loams with a complete cover of basalt cobbles and stones. Large areas of talus or rock slides occur intermingled with soil areas. Plant-soil moisture relationships are fair.
Soils mapped on this site include: SSA-664 San Simon area MU's 5 & 25 Graham; SSA-669 Pima county Eastern part MU 32 Graham; SSA-671 Cochise county Douglas-Tombstone part MU's 16 Boss, Krentz & Paramore, 75 Graham & Lampshire.Table 4. Representative soil features
Parent material (1) Slope alluvium – basalt
Surface texture (1) Loam
(2) Clay loam
Permeability class Moderate 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 fire, grazing, 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 amount shown for each group. Divide the resulting total by the total normal year production shown in the plant community description. If the rainfall has ben 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 CommunityThe potential plant community on this site is dominated by warm season perennial grasses. Shrubs are well represented on the site, as well as perennial and annual forbs. The major grass species tend to be well dispersed througout the plant community. Shrubs are concentrated at the edge of outcrops and along talus slides. The aspect is dotted grassland.
Figure 4. Annual production by plant type (representative values) or group (midpoint values)
Table 5. Annual production by plant type
Plant type Low
(kg/hectare)Representative value
(kg/hectare)High
(kg/hectare)Grass/Grasslike 605 – 706 Shrub/Vine 202 – 303 Forb 101 – 151 Total 908 – 1160 Figure 5. Plant community growth curve (percent production by month). AZ4131 , 41.3 12-16" p.z. hill sites. Growth begins in the spring, semi-dormancy occurs during the June drought, most growth occurs during the summer rainy season..
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec J F M A M J J A S O N D 0 0 5 10 10 0 30 30 10 5 0 0 Additional community tables
Table 6. Community 1.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Grass/Grasslike1 202–303 black grama BOER4 Bouteloua eriopoda 202–303 – 2 151–252 sideoats grama BOCU Bouteloua curtipendula 151–252 – 3 303 cane bluestem BOBA3 Bothriochloa barbinodis 303 – Arizona cottontop DICA8 Digitaria californica 303 – bush muhly MUPO2 Muhlenbergia porteri 303 – 4 50–101 Orcutt's threeawn ARSCO Aristida schiedeana var. orcuttiana 50–101 – spidergrass ARTE3 Aristida ternipes 50–101 – spidergrass ARTEG Aristida ternipes var. gentilis 50–101 – plains lovegrass ERIN Eragrostis intermedia 50–101 – tanglehead HECO10 Heteropogon contortus 50–101 – green sprangletop LEDU Leptochloa dubia 50–101 – tobosagrass PLMU3 Pleuraphis mutica 50–101 – plains bristlegrass SEVU2 Setaria vulpiseta 50–101 – spike dropseed SPCO4 Sporobolus contractus 50–101 – sand dropseed SPCR Sporobolus cryptandrus 50–101 – 5 10–50 sixweeks threeawn ARAD Aristida adscensionis 10–50 – needle grama BOAR Bouteloua aristidoides 10–50 – sixweeks grama BOBA2 Bouteloua barbata 10–50 – Arizona brome BRAR4 Bromus arizonicus 10–50 – feather fingergrass CHVI4 Chloris virgata 10–50 – desert lovegrass ERPEM Eragrostis pectinacea var. miserrima 10–50 – little barley HOPU Hordeum pusillum 10–50 – Mexican sprangletop LEFUU Leptochloa fusca ssp. uninervia 10–50 – mucronate sprangletop LEPA6 Leptochloa panicea 10–50 – Arizona signalgrass URAR Urochloa arizonica 10–50 – sixweeks fescue VUOC Vulpia octoflora 10–50 – 6 10–50 low woollygrass DAPU7 Dasyochloa pulchella 10–50 – nineawn pappusgrass ENDE Enneapogon desvauxii 10–50 – Palmer's crinklemat TIPA Tiquilia palmeri 10–50 – slim tridens TRMU Tridens muticus 10–50 – 7 10–50 sprucetop grama BOCH Bouteloua chondrosioides 10–50 – blue grama BOGR2 Bouteloua gracilis 10–50 – hairy grama BOHI2 Bouteloua hirsuta 10–50 – purple grama BORA Bouteloua radicosa 10–50 – slender grama BORE2 Bouteloua repens 10–50 – curly-mesquite HIBE Hilaria belangeri 10–50 – common wolfstail LYPH Lycurus phleoides 10–50 – Hall's panicgrass PAHA Panicum hallii 10–50 – vine mesquite PAOB Panicum obtusum 10–50 – 8 10–50 poverty threeawn ARDI5 Aristida divaricata 10–50 – Havard's threeawn ARHA3 Aristida havardii 10–50 – Wooton's threeawn ARPA9 Aristida pansa 10–50 – purple threeawn ARPU9 Aristida purpurea 10–50 – blue threeawn ARPUN Aristida purpurea var. nealleyi 10–50 – sedge CAREX Carex 10–50 – squirreltail ELELE Elymus elymoides ssp. elymoides 10–50 – bullgrass MUEM Muhlenbergia emersleyi 10–50 – creeping muhly MURE Muhlenbergia repens 10–50 – slender muhly MUTE4 Muhlenbergia tenuifolia 10–50 – Texas bluestem SCCI2 Schizachyrium cirratum 10–50 – slim tridens TRMUE Tridens muticus var. elongatus 10–50 – Forb9 50–101 dwarf Indian mallow ABPA3 Abutilon parvulum 50–101 – San Felipe dogweed ADPO Adenophyllum porophylloides 50–101 – trailing windmills ALIN Allionia incarnata 50–101 – weakleaf bur ragweed AMCO3 Ambrosia confertiflora 50–101 – anoda ANODA Anoda 50–101 – desert marigold BAMU Baileya multiradiata 50–101 – spreading fleabane ERDI4 Erigeron divergens 50–101 – Arizona snakecotton FRAR2 Froelichia arizonica 50–101 – haplopappus HAPLO11 Haplopappus 50–101 – slender janusia JAGR Janusia gracilis 50–101 – tree tobacco NIGL Nicotiana glauca 50–101 – Wright's cudweed PSCAC2 Pseudognaphalium canescens ssp. canescens 50–101 – twinleaf senna SEBA3 Senna bauhinioides 50–101 – spreading fanpetals SIAB Sida abutifolia 50–101 – desert globemallow SPAM2 Sphaeralcea ambigua 50–101 – brownplume wirelettuce STPA4 Stephanomeria pauciflora 50–101 – 10 50 carelessweed AMPA Amaranthus palmeri 50 – pioneer rockcress ARPL Arabis platysperma 50 – clasping milkweed ASAM Asclepias amplexicaulis 50 – aster ASTER Aster 50 – milkvetch ASTRA Astragalus 50 – hairyseed bahia BAAB Bahia absinthifolia 50 – spiderling BOERH2 Boerhavia 50 – hoary bowlesia BOIN3 Bowlesia incana 50 – lipfern CHEIL Cheilanthes 50 – goosefoot CHENO Chenopodium 50 – fingerleaf gourd CUDI Cucurbita digitata 50 – American wild carrot DAPU3 Daucus pusillus 50 – western tansymustard DEPI Descurainia pinnata 50 – fetid marigold DYPA Dyssodia papposa 50 – flatcrown buckwheat ERDE6 Eriogonum deflexum 50 – spurge EUPHO Euphorbia 50 – Indian rushpea HOGL2 Hoffmannseggia glauca 50 – redstar IPCO3 Ipomoea coccinea 50 – ragged nettlespurge JAMA Jatropha macrorhiza 50 – prickly lettuce LASE Lactuca serriola 50 – shaggyfruit pepperweed LELA Lepidium lasiocarpum 50 – intermediate pepperweed LEVIM Lepidium virginicum var. medium 50 – common deerweed LOSC2 Lotus scoparius 50 – blazingstar MENTZ Mentzelia 50 – minerslettuce MONTI Montia 50 – cloak fern NOTHO Notholaena 50 – owl's-clover ORTHO Orthocarpus 50 – Florida pellitory PAFL3 Parietaria floridana 50 – chinchweed PECTI Pectis 50 – cliffbrake PELLA Pellaea 50 – Parry's beardtongue PEPA24 Penstemon parryi 50 – Nine Mile Canyon phacelia PHNO Phacelia novenmillensis 50 – desert Indianwheat PLOV Plantago ovata 50 – silverleaf nightshade SOEL Solanum elaeagnifolium 50 – pricklyleaf dogweed THAC Thymophylla acerosa 50 – rue of the mountains THTE2 Thamnosma texana 50 – woolly tidestromia TILA2 Tidestromia lanuginosa 50 – catnip noseburn TRNE Tragia nepetifolia 50 – verbena VEPO4 Verbena polystachya 50 – American vetch VIAM Vicia americana 50 – garden vetch VISAN2 Vicia sativa ssp. nigra 50 – Shrub/Vine11 50–101 whitethorn acacia ACCO2 Acacia constricta 50–101 – Wright's beebrush ALWR Aloysia wrightii 50–101 – Palmer's cock's comb CEPA5 Celosia palmeri 50–101 – creosote bush LATRT Larrea tridentata var. tridentata 50–101 – 12 50–101 pelotazo ABIN Abutilon incanum 50–101 – fourwing saltbush ATCA2 Atriplex canescens 50–101 – yerba de pasmo BAPT Baccharis pteronioides 50–101 – resinleaf brickellbush BRBA2 Brickellia baccharidea 50–101 – fairyduster CAER Calliandra eriophylla 50–101 – Cooley's bundleflower DECO2 Desmanthus cooleyi 50–101 – ookow DICO19 Dichelostemma congestum 50–101 – longleaf jointfir EPTR Ephedra trifurca 50–101 – bastardsage ERWR Eriogonum wrightii 50–101 – rock sage SAPI2 Salvia pinguifolia 50–101 – American threefold TRCA8 Trixis californica 50–101 – desert zinnia ZIAC Zinnia acerosa 50–101 – 13 10–50 pelotazo ABIN Abutilon incanum 10–50 – prairie acacia ACAN Acacia angustissima 10–50 – catclaw acacia ACGR Acacia greggii 10–50 – milfoil wattle ACMI Acacia millefolia 10–50 – netleaf hackberry CELAR Celtis laevigata var. reticulata 10–50 – oneseed juniper JUMO Juniperus monosperma 10–50 – desert-thorn LYCIU Lycium 10–50 – mariola PAIN2 Parthenium incanum 10–50 – honey mesquite PRGLG Prosopis glandulosa var. glandulosa 10–50 – littleleaf sumac RHMI3 Rhus microphylla 10–50 – Wright's mock buckthorn SAWR Sageretia wrightii 10–50 – woody crinklemat TICAC Tiquilia canescens var. canescens 10–50 – lotebush ZIOB Ziziphus obtusifolia 10–50 – 14 10–20 desertbroom BASA2 Baccharis sarothroides 10–20 – threadleaf snakeweed GUMI Gutierrezia microcephala 10–20 – broom snakeweed GUSA2 Gutierrezia sarothrae 10–20 – burroweed ISTE2 Isocoma tenuisecta 10–20 – alyssumleaf phlox PHALA4 Phlox alyssifolia ssp. abdita 10–20 – Douglas' spikemoss SEDO Selaginella douglasii 10–20 – 15 10–50 desert agave AGDE Agave deserti 10–50 – Bill Williams Mountain giant hyssop AGPA Agastache pallidiflora 10–50 – common sotol DAWH2 Dasylirion wheeleri 10–50 – candy barrelcactus FEWI Ferocactus wislizeni 10–50 – ocotillo FOSP2 Fouquieria splendens 10–50 – globe cactus MAMMI Mammillaria 10–50 – sacahuista NOMI Nolina microcarpa 10–50 – beavertail pricklypear OPBA2 Opuntia basilaris 10–50 – limestone adderstongue OPEN Ophioglossum engelmannii 10–50 – banana yucca YUBA Yucca baccata 10–50 – Schott's yucca YUSC Yucca ×schottii 10–50 – Interpretations
Animal community
This site produces fair quality herbaceous forage. High soil pH is somewhat offset by inherent soil fertility. The site is not well suited to summertime grazing by cows with calves. Mother cow pairs will only use 300-400 feet, up or down in elevation, from water in the summer. Dry cows will use double that distance in the cool season. Yearling cattle make good use of the site in any season. Slope aspect affects both the intensity of use and seasonal use patterns. North-south trending slopes will be used fairly well even in summer, as the wets slope is shady in the morning and the east slope is shady in the afternoon. South facing slopes are used heavily in the winter-spring due to warmth from cold weather and early greenup of warm season grasses. North facing slopes, bieng shady and cooler, are used in the summer, and especially in the fall as the perennial grasses stay greener longer into the cool season. Very dar colored rock and soil surfaces cause early soil warming and, consequently, earlier greenup of warm season perennial grasses in the spring. Seep and canyon water is available in most winters from December-February.
Water developments are very important to wildlife on this site. The site is home to a wide variety of wildlife species due to the diversity of food, cover and edge.Supporting information
Type locality
Location 1: Cochise County, AZ Township/Range/Section T23S R29E S29 General legal description Rocker M Ranch Location 2: Pima County, AZ Township/Range/Section T18S R10E S28 General legal description Batamote Ranch Location 3: Cochise County, AZ Township/Range/Section T20S R24E S7 General legal description Cowan Ranch Contributors
Dan Robinett
Larry D. Ellicott
Steve Barker
Unknown
UnknwonRangeland 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) Dave Womack, Dan Robinett, Emilio Carrillo Contact for lead author USDA-NRCS Tucson Area Office Date 02/25/2005 Approved by Approval date Composition (Indicators 10 and 12) based on Annual Production Indicators
-
Number and extent of rills:
None present on this site. -
Presence of water flow patterns:
Uncommon; probably cover no more than 10% of area; discontinuous; very short, usually less than 1 foot in length; broken primarily by high rock and gravel cover. -
Number and height of erosional pedestals or terracettes:
Pedestals are uncommon on perennial grass and shrubs; Limited soil material not conducive to forming continuous stands of plants that promote terracettes; high rock cover forms limited natural terracettes. -
Bare ground from Ecological Site Description or other studies (rock, litter, lichen, moss, plant canopy are not bare ground):
Estimated at 0-5%. -
Number of gullies and erosion associated with gullies:
None present on this site. -
Extent of wind scoured, blowouts and/or depositional areas:
None present on this site. -
Amount of litter movement (describe size and distance expected to travel):
All litter size classes staying in place. -
Soil surface (top few mm) resistance to erosion (stability values are averages - most sites will show a range of values):
No slake test done. Expect values of 1-2 in canopy interspaces, and 4 - 6 under plant canopies. -
Soil surface structure and SOM content (include type of structure and A-horizon color and thickness):
Weak coarse granular; Color is 10YR5/4 Dry, 10YR3/2 Moist; thickness to 3 inches. -
Effect of community phase composition (relative proportion of different functional groups) and spatial distribution on infiltration and runoff:
Cover estimated as: Canopy 20-30%, Basal 5%, Litter 45-55%, and Gravel 30%; 10% of canopy cover is perennial mid grasses, 25% short grasses, 5% perennial forbs, 45% shrubs and 10% subshrubs. Cover is well dispersed throughout site. -
Presence and thickness of compaction layer (usually none; describe soil profile features which may be mistaken for compaction on this site):
None present on this site. -
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:
Perennial grass = shrubsSub-dominant:
annual grasses & forbs > subshrubs > succulents = perennial forbsOther:
Additional:
-
Amount of plant mortality and decadence (include which functional groups are expected to show mortality or decadence):
2-3% of perennial grass plants have died with skeletons still present; 50% of basal cover of perennial grasses has been lost in recent prolonged drought. -
Average percent litter cover (%) and depth ( in):
-
Expected annual annual-production (this is TOTAL above-ground annual-production, not just forage annual-production):
600 lbs/acre unfavorable precipitation, 900 lbs/acre normal precipitation, 1,300 lbs/acre favorable precipitation. -
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:
turpentine bush, jojoba, whitethorn, mesquite, prickly pear, cane cholla, ocotillo may increase to undesirable levels in the absence of natural fires; Red brome and wild oats. -
Perennial plant reproductive capability:
Not affected even following several years of prolonged drought period for region.
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