Natural Resources
Conservation Service
Ecological site R041XB208AZ
Limy Upland
8-12" p.z.
Last updated: 7/28/2020
Accessed: 04/22/2026
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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 41.2 – Chihuahuan – Sonoran Desert Shrubs
Elevations range from 2600 to 4000 feet and precipitation ranges from 8 to 12 inches per year. Vegetation includes mesquite, palo verde, catclaw acacia, soaptree yucca, creosotebush, whitethorn, staghorn cholla, desert saltbush, Mormon tea, burroweed, snakeweed, tobosa, black grama, threeawns, bush muhly, dropseed, and burrograss. The soil temperature regime is thermic and the soil moisture regime is typic 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.Associated sites
F041XB221AZ Loamy Bottom 8-12" p.z. woodland
F041XB222AZ Saline Bottom 8-12" p.z. woodland
R041XB206AZ Limy Fan 8-12" p.z.
R041XB207AZ Limy Slopes 8-12" p.z.
Similar sites
R040XA111AZ Limy Upland 10"-13" p.z.
R041XC309AZ Limy Upland 12-16" p.z.
Table 1. Dominant plant species
Tree Not specified
Shrub (1) larrea tridentata
Herbaceous (1) muhlenbergia porteri
(2) aristidaPhysiographic features
This site occurs in the lowest elevations of the Madrean Basin and Range province in southeastern Arizona. It occurs on fan terraces and ridge-tops. It occurs in the Gila and San Pedro river valleys.
Table 2. Representative physiographic features
Landforms (1) Fan piedmont
(2) Fan remnant
(3) Ridge
Flooding frequency None Ponding frequency None Elevation 792 – 1219 m Slope 1 – 15 % Aspect Aspect is not a significant factor Climatic features
Precipitation ranges from 8-12 inches annually. More than half falls during July-Sep in brief, but often heavy, thunderstorms. The rest of the moisture comes as light rain or snow that falls slowly for a day or more, but rarely lasts more than a day. May and June are normally the driest months. Humidity is generally very low.
Temperatures are mild throughout most of the year. Freezing temperatures are common at night Dec-Feb; brief 0 F may be observed some nights. During June, July & August some days may exceed 100 F.
In years of average or greater winter precipitation, annual grasses and forbs occur abundantly in the interspaces.Table 3 Representative climatic features
Frost-free period (average) 240 days Freeze-free period (average) Precipitation total (average) BarLineFigure 2. Monthly precipitation range
BarLineFigure 3. Monthly average minimum and maximum temperature
">Influencing water features
There are no water features associated with this site.
Soil features
These soils are well drained, coarse textured, stratified and high in calcium carbonates. They are shallow and underlain by lime and/or silica cemented pans or very gravelly, lime cemented, conglomerate. They have formed in old fan deposits.
Soil series mapped on this site include: SSA-662 Safford area MU's BeB BpB PsB & ThC Bitter Spring, ChB ChE CkD & PuB Cave, WhA WkA & WkB Whitlock; SSA-663 Gila-Duncan area MU's 25 26 & 41 Piloncillo, 29 & 45 Whitlock; SSA-664 San Simon area MU 44 Vekol; SSA-666 Cochise county Northwest part MU's 8 Borderline and 27 Monzingo; SSA-671 Cochise county Douglas-Tombstone part MU's 15 Borderline FSL, 35 & 111 Monzingo, 47 Dona Ana; SSA-675 San Carlos IR area MU 17 Bylas.Table 4. Representative soil features
Surface texture (1) Very gravelly sandy loam
(2) Very gravelly fine sandy loam
(3) Sandy loam
Family particle size (1) Loamy
Drainage class Well drained Permeability class Moderately rapid to moderate Soil depth 13 – 51 cm Surface fragment cover <=3" 15 – 50 % Surface fragment cover >3" 0 – 15 % Available water capacity
(0-101.6cm)1.27 – 4.32 cm Calcium carbonate equivalent
(0-101.6cm)10 – 30 % Electrical conductivity
(0-101.6cm)0 – 2 mmhos/cm Sodium adsorption ratio
(0-101.6cm)0 – 2 Soil reaction (1:1 water)
(0-101.6cm)7.4 – 8.4 Subsurface fragment volume <=3"
(Depth not specified)15 – 60 % Subsurface fragment volume >3"
(Depth not specified)0 – 5 % 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 community found on relict or relatively undisturbed areas of this site. Other plant communities described here represent plant communities that are known to occur when the site is disturbed by factors such as fire, grazing and 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 described in the 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 amount shown for that group. Divide the resulting total by the total, normal year, production shown in the plant community description. If the rainfall has been significantly above or below normal, use the total production shown for above or below normal years. If the field data is not collected at the end of the summer growing season, then the field data must be corrected to the end of 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.
The historic native state includes the native plant communities that occur on the site, including the historic climax plant community. This state includes other plant communities that naturally occupy the site following fire, drought, flooding, herbivores and other natural disturbances. The historic climax plant community represents the natural climax community that eventually reoccupies the site with proper management and a return to near normal conditions and/or equilibrium.State and transition model
Custom diagramStandard diagram
Figure 4. State and Transition, Limy Upland 8-12" p.z.
More interactive model formats are also available. View Interactive Models
More interactive model formats are also available. View Interactive Models
Click on state and transition labels to scroll to the respective textEcosystem states
State 1 submodel, plant communities
State 2 submodel, plant communities
State 1
Historic Climax Plant CommunityCommunity 1.1
Historic Climax Plant Community
Figure 5. Limy Upland 8-12" pz. soil pit
This plant community is dominated by creosote bush. Annual grasses and forbs are an important part of the plant community in wet seasons. Perennial grasses and forbs are minor components in the potential plant community. Cryptogams are common on this site, often colonizing areas with low gravel covers.
Figure 6. 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)Shrub/Vine 87 196 280 Grass/Grasslike 8 22 123 Forb 1 6 67 Total 96 224 470 Table 6. Soil surface cover
Tree basal cover 0% Shrub/vine/liana basal cover 0-0% Grass/grasslike basal cover 0-0% Forb basal cover 0-0% Non-vascular plants 0% Biological crusts 10-20% Litter 0-20% Surface fragments >0.25" and <=3" 20-50% Surface fragments >3" 0-20% Bedrock 0% Water 0% Bare ground 10-80% Table 7. Canopy structure (% cover)
Height Above Ground (m) Tree Shrub/Vine Grass/
GrasslikeForb <0.15 – 0-2% 0-5% 0-5% >0.15 <= 0.3 – 1-5% 1-5% 0-5% >0.3 <= 0.6 – 0-2% 1-3% 0-2% >0.6 <= 1.4 – 5-10% 0-2% 0-1% >1.4 <= 4 – 0-1% – – >4 <= 12 – – – – >12 <= 24 – – – – >24 <= 37 – – – – >37 – – – – State 2
Shrub, annualsCommunity 2.1
Shrub, annualsThis state occurs where the native shrub cover is still dominant but the herbaceous layer of the plant community is dominated by non-native annual grasses and forbs. These species can include filaree, mediterranean grass, red brome, malta starthistle and Sahara mustard.
Transition T1A
State 1 to 2Introductions of a seed source of non-natives, Continuous Heavy Grazing. Possible competition ofexotics with native species of forbs or grasses.
Restoration pathway R2A
State 2 to 1Unknown
Additional community tables
Table 8. Community 1.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Grass/Grasslike1 Dominant perennial grasses 8–67 bush muhly MUPO2 Muhlenbergia porteri 6–45 – blue threeawn ARPUN Aristida purpurea var. nealleyi 1–22 – low woollygrass DAPU7 Dasyochloa pulchella 1–22 – black grama BOER4 Bouteloua eriopoda 0–17 – slim tridens TRMU Tridens muticus 0–17 – Parish's threeawn ARPUP5 Aristida purpurea var. parishii 0–11 – 2 Misc. perennial grasses 0–22 purple threeawn ARPU9 Aristida purpurea 0–6 – spidergrass ARTE3 Aristida ternipes 0–6 – spidergrass ARTEG Aristida ternipes var. gentilis 0–6 – tobosagrass PLMU3 Pleuraphis mutica 0–6 – Hall's panicgrass PAHA Panicum hallii 0–2 – whiplash pappusgrass PAVA2 Pappophorum vaginatum 0–2 – alkali sacaton SPAI Sporobolus airoides 0–2 – sand dropseed SPCR Sporobolus cryptandrus 0–2 – mesa dropseed SPFL2 Sporobolus flexuosus 0–2 – sideoats grama BOCU Bouteloua curtipendula 0–2 – Arizona cottontop DICA8 Digitaria californica 0–1 – squirreltail ELEL5 Elymus elymoides 0–1 – nineawn pappusgrass ENDE Enneapogon desvauxii 0–1 – Arizona muhly MUAR3 Muhlenbergia arizonica 0–1 – spike dropseed SPCO4 Sporobolus contractus 0–1 – burrograss SCBR2 Scleropogon brevifolius 0–1 – plains bristlegrass SEVU2 Setaria vulpiseta 0–1 – 3 Annual grasses 0–34 prairie threeawn AROL Aristida oligantha 0–11 – needle grama BOAR Bouteloua aristidoides 0–11 – sixweeks grama BOBA2 Bouteloua barbata 0–11 – Rothrock's grama BORO2 Bouteloua rothrockii 0–6 – witchgrass PACA6 Panicum capillare 0–6 – sixweeks threeawn ARAD Aristida adscensionis 0–6 – delicate muhly MUFR Muhlenbergia fragilis 0–2 – littleseed muhly MUMI Muhlenbergia microsperma 0–2 – Bigelow's bluegrass POBI Poa bigelovii 0–2 – Arizona signalgrass URAR Urochloa arizonica 0–2 – sixweeks fescue VUOC Vulpia octoflora 0–2 – Mexican panicgrass PAHI5 Panicum hirticaule 0–1 – Arizona brome BRAR4 Bromus arizonicus 0–1 – canyon cupgrass ERLE7 Eriochloa lemmonii 0–1 – desert lovegrass ERPEM Eragrostis pectinacea var. miserrima 0–1 – tufted lovegrass ERPEP2 Eragrostis pectinacea var. pectinacea 0–1 – Mexican sprangletop LEFUU Leptochloa fusca ssp. uninervia 0–1 – mucronate sprangeltop LEPAB Leptochloa panicea ssp. brachiata 0–1 – Forb4 Perennial Forbs 1–11 dwarf desertpeony ACNA2 Acourtia nana 1–6 – pricklyleaf dogweed THAC Thymophylla acerosa 0–2 – rue of the mountains THTE2 Thamnosma texana 0–2 – weakleaf bur ragweed AMCO3 Ambrosia confertiflora 0–2 – leatherweed CRPO5 Croton pottsii 0–2 – bluedicks DICA14 Dichelostemma capitatum 0–1 – desert trumpet ERIN4 Eriogonum inflatum 0–1 – Parry's false prairie-clover MAPA7 Marina parryi 0–1 – lacy tansyaster MAPIP4 Machaeranthera pinnatifida ssp. pinnatifida var. pinnatifida 0–1 – wishbone-bush MILAV Mirabilis laevis var. villosa 0–1 – desert tobacco NIOB Nicotiana obtusifolia 0–1 – slender poreleaf POGR5 Porophyllum gracile 0–1 – glandleaf milkwort POMA7 Polygala macradenia 0–1 – Coues' cassia SECO10 Senna covesii 0–1 – silverleaf nightshade SOEL Solanum elaeagnifolium 0–1 – desert globemallow SPAM2 Sphaeralcea ambigua 0–1 – brownplume wirelettuce STPA4 Stephanomeria pauciflora 0–1 – tuber anemone ANTU Anemone tuberosa 0–1 – New Mexico silverbush ARNE2 Argythamnia neomexicana 0–1 – dense ayenia AYMI Ayenia microphylla 0–1 – hairyseed bahia BAAB Bahia absinthifolia 0–1 – desert marigold BAMU Baileya multiradiata 0–1 – scarlet spiderling BOCO Boerhavia coccinea 0–1 – whitemargin sandmat CHAL11 Chamaesyce albomarginata 0–1 – branched noseburn TRRA5 Tragia ramosa 0–1 – brownfoot ACWR5 Acourtia wrightii 0–1 – poreleaf dogweed ADPO2 Adenophyllum porophyllum 0–1 – trailing windmills ALIN Allionia incarnata 0–1 – 5 Annual forbs 0–56 cryptantha CRYPT Cryptantha 0–17 – Esteve's pincushion CHST Chaenactis stevioides 0–11 – flatcrown buckwheat ERDE6 Eriogonum deflexum 0–11 – combseed PECTO Pectocarya 0–11 – manybristle chinchweed PEPA2 Pectis papposa 0–11 – phacelia PHACE Phacelia 0–11 – bristly fiddleneck AMTE3 Amsinckia tessellata 0–11 – exserted Indian paintbrush CAEXE Castilleja exserta ssp. exserta 0–11 – desert Indianwheat PLOV Plantago ovata 0–11 – chia SACO6 Salvia columbariae 0–6 – lyreleaf jewelflower STCA5 Streptanthus carinatus 0–6 – thelypody THELY Thelypodium 0–6 – woolly tidestromia TILA2 Tidestromia lanuginosa 0–6 – yellow tackstem CAPA7 Calycoseris parryi 0–6 – white tackstem CAWR Calycoseris wrightii 0–6 – Nuttall's povertyweed MONU Monolepis nuttalliana 0–6 – Gordon's bladderpod LEGO Lesquerella gordonii 0–6 – shaggyfruit pepperweed LELA Lepidium lasiocarpum 0–6 – intermediate pepperweed LEVIM Lepidium virginicum var. medium 0–6 – coastal bird's-foot trefoil LOSAB Lotus salsuginosus var. brevivexillus 0–6 – slender goldenweed MAGR10 Machaeranthera gracilis 0–6 – miniature woollystar ERDI2 Eriastrum diffusum 0–6 – western tansymustard DEPI Descurainia pinnata 0–6 – Coulter's spiderling BOCO2 Boerhavia coulteri 0–6 – hairy prairie clover DAMO Dalea mollis 0–2 – fringed redmaids CACI2 Calandrinia ciliata 0–2 – American wild carrot DAPU3 Daucus pusillus 0–2 – sorrel buckwheat ERPO4 Eriogonum polycladon 0–2 – Texas stork's bill ERTE13 Erodium texanum 0–2 – California poppy ESCAM Eschscholzia californica ssp. mexicana 0–2 – tanseyleaf tansyaster MATA2 Machaeranthera tanacetifolia 0–2 – hairy desertsunflower GECA2 Geraea canescens 0–2 – star gilia GIST Gilia stellata 0–2 – Coulter's lupine LUSP2 Lupinus sparsiflorus 0–2 – green carpetweed MOVE Mollugo verticillata 0–2 – brittle spineflower CHBR Chorizanthe brevicornu 0–2 – hyssopleaf sandmat CHHY3 Chamaesyce hyssopifolia 0–2 – woollyhead neststraw STMI2 Stylocline micropoides 0–2 – Arizona poppy KAGR Kallstroemia grandiflora 0–2 – desert evening primrose OEPR Oenothera primiveris 0–2 – Florida pellitory PAFL3 Parietaria floridana 0–2 – doubleclaw PRPA2 Proboscidea parviflora 0–1 – New Mexico plumeseed RANE Rafinesquia neomexicana 0–1 – sawtooth sage SASU7 Salvia subincisa 0–1 – spreading fanpetals SIAB Sida abutifolia 0–1 – sleepy silene SIAN2 Silene antirrhina 0–1 – Coulter's globemallow SPCO2 Sphaeralcea coulteri 0–1 – sand fringepod THCU Thysanocarpus curvipes 0–1 – southwestern pricklypoppy ARPL3 Argemone pleiacantha 0–1 – milkvetch ASTRA Astragalus 0–1 – wheelscale saltbush ATEL Atriplex elegans 0–1 – annual agoseris AGHE2 Agoseris heterophylla 0–1 – carelessweed AMPA Amaranthus palmeri 0–1 – bristly nama NAHI Nama hispidum 0–1 – glandular threadplant NEGL Nemacladus glanduliferus 0–1 – Arizona popcornflower PLAR Plagiobothrys arizonicus 0–1 – crestrib morning-glory IPCO2 Ipomoea costellata 0–1 – Mexican fireplant EUHE4 Euphorbia heterophylla 0–1 – sanddune wallflower ERCA14 Erysimum capitatum 0–1 – common woolly sunflower ERLA6 Eriophyllum lanatum 0–1 – soft prairie clover DAMO2 Dalea mollissima 0–1 – hoary bowlesia BOIN3 Bowlesia incana 0–1 – scrambled eggs COAU2 Corydalis aurea 0–1 – Shrub/Vine6 Dominant shrub 84–224 creosote bush LATR2 Larrea tridentata 84–224 – 7 Miscellaneous shrubs 1–22 jojoba SICH Simmondsia chinensis 0–6 – whitethorn acacia ACCO2 Acacia constricta 0–6 – mariola PAIN2 Parthenium incanum 0–6 – western honey mesquite PRGLT Prosopis glandulosa var. torreyana 0–2 – whitethorn acacia ACCOP9 Acacia constricta var. paucispina 0–2 – viscid acacia ACNE4 Acacia neovernicosa 0–2 – Wright's beebrush ALWR Aloysia wrightii 0–1 – fourwing saltbush ATCA2 Atriplex canescens 0–1 – cattle saltbush ATPO Atriplex polycarpa 0–1 – crucifixion thorn CAHO3 Canotia holacantha 0–1 – longleaf jointfir EPTR Ephedra trifurca 0–1 – American tarwort FLCE Flourensia cernua 0–1 – ocotillo FOSP2 Fouquieria splendens 0–1 – crown of thorns KOSP Koeberlinia spinosa 0–1 – water jacket LYAN Lycium andersonii 0–1 – pale desert-thorn LYPA Lycium pallidum 0–1 – lotebush ZIOB Ziziphus obtusifolia 0–1 – catclaw acacia ACGR Acacia greggii 0–1 – 8 Half shrubs 1–22 desert zinnia ZIAC Zinnia acerosa 1–11 – rough menodora MESC Menodora scabra 1–6 – whitestem paperflower PSCO2 Psilostrophe cooperi 0–6 – littleleaf ratany KRER Krameria erecta 1–6 – rayless goldenhead ACSP Acamptopappus sphaerocephalus 0–6 – burrobush AMDU2 Ambrosia dumosa 0–6 – winterfat KRLA2 Krascheninnikovia lanata 0–2 – woody crinklemat TICA3 Tiquilia canescens 0–1 – shortleaf baccharis BABR Baccharis brachyphylla 0–1 – fairyduster CAER Calliandra eriophylla 0–1 – featherplume DAFO Dalea formosa 0–1 – threadleaf snakeweed GUMI Gutierrezia microcephala 0–1 – broom snakeweed GUSA2 Gutierrezia sarothrae 0–1 – burroweed ISTE2 Isocoma tenuisecta 0–1 – 9 Succulents 1–11 Christmas cactus CYLE8 Cylindropuntia leptocaulis 0–2 – purple pricklypear OPMA8 Opuntia macrocentra 0–2 – tulip pricklypear OPPH Opuntia phaeacantha 0–2 – banana yucca YUBA Yucca baccata 0–2 – soaptree yucca YUEL Yucca elata 0–1 – nightblooming cereus PEGR3 Peniocereus greggii 0–1 – walkingstick cactus CYSP8 Cylindropuntia spinosior 0–1 – Engelmann's hedgehog cactus ECEN Echinocereus engelmannii 0–1 – redspine fishhook cactus ECER2 Echinomastus erectocentrus 0–1 – pinkflower hedgehog cactus ECFA Echinocereus fasciculatus 0–1 – candy barrelcactus FEWI Ferocactus wislizeni 0–1 – devil's cholla GRKU Grusonia kunzei 0–1 – Graham's nipple cactus MAGR9 Mammillaria grahamii 0–1 – cactus apple OPEN3 Opuntia engelmannii 0–1 – buck-horn cholla CYAC8 Cylindropuntia acanthocarpa 0–1 – Table 9. Community 2.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Interpretations
Animal community
This site offers little in the way of perennial forage for livestock. Annual grasses and forbs offer limited grazing in wet winters. High pH, due to calcium carbonates in the soil, lower the availability of essential plant nutrients and reduce the palatability of grasses to livestock. Adjacent, non-limy sites will be overused before appreciable use is made of this site.
Wildlife on this site is limited to small mammals and birds and their associated predators.Hydrological functions
Coarse textured soils with very gravelly surfaces make this site a poor producer of runoff.
Recreational uses
Hunting, horseback riding, hiking, photography, bird watching.
Other products
Gravel
Supporting information
Contributors
Dan Robinett
Larry D. EllicottApproval
Scott Woodall, 7/28/2020
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) Wilma Renken, Dan Robinett, Larry Humphrey Contact for lead author USDA-NRCS Tucson MLRA Soil Survey Office Date 11/05/2012 Approved by Approval date Composition (Indicators 10 and 12) based on Annual Production Indicators
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Number and extent of rills:
None -
Presence of water flow patterns:
Water flow paths are not distinct but occur between clumps of creosote bush. They occupy 30-40% of the area and are discontinuous, averaging 20-30 feet in length. -
Number and height of erosional pedestals or terracettes:
Terrecettes do not occur. Pedestals occur on creosote bush and are 2-3 inches in height. -
Bare ground from Ecological Site Description or other studies (rock, litter, lichen, moss, plant canopy are not bare ground):
Bare ground from the reference site was 36% with 45% gravel cover. Non-vegetated areas are plant/ shrub interspaces; soil is well armored with gravel. Actual exposed soil areas are small (<2’ in diameter) and not connected. -
Number of gullies and erosion associated with gullies:
None -
Extent of wind scoured, blowouts and/or depositional areas:
None -
Amount of litter movement (describe size and distance expected to travel):
None observed, but in some years fine litter classes can move short distances (2 -3 feet). All coarse litter classes stay in place. -
Soil surface (top few mm) resistance to erosion (stability values are averages - most sites will show a range of values):
Average value from soil slake test is 3. The average value from areas without canopy cover is 2 and average values from areas with creosote canopy is 4.3 -
Soil surface structure and SOM content (include type of structure and A-horizon color and thickness):
A horizon is two inches thick with a weak granular structure. Surface soil colors are 10 YR 5/3 dry and 10YR 3/4 moist. -
Effect of community phase composition (relative proportion of different functional groups) and spatial distribution on infiltration and runoff:
13% canopy cover. Shrubs are evenly distributed across site. Perennial grasses are generally confined within shrub canopies. -
Presence and thickness of compaction layer (usually none; describe soil profile features which may be mistaken for compaction on this site):
None. Abrupt change in texture from the B2tk horizon to the Ck horizon (at 12 inches) can be mistaken for a compaction zone. This is a laminar cap of cemented calcium carbonates on top of the Ck horizon. Average depth of penetration from a field penetrometer with a 2 kg sliding hammer is 7.6 cm. -
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:
Dom.Shrub (creosote) >>Sub-dominant:
Dom.Per.Grasses > Misc.Shrubs = Half Shrubs = Succulents > Misc.Per.Grasses = Annuals = Per.ForbsOther:
Additional:
Annuals fluctuate based on weather cycles. -
Amount of plant mortality and decadence (include which functional groups are expected to show mortality or decadence):
Complete mortality of perennial grasses and sub-shrubs in past several years due to severe drought since 2002. -
Average percent litter cover (%) and depth ( in):
Litter is mainly from annual grasses like needle grama, annual threeawn and six weeks grama. Coarse litter is all from creosote bush and tends to stay under the canopy. -
Expected annual annual-production (this is TOTAL above-ground annual-production, not just forage annual-production):
86 lbs/ac for a below average year; 200 lbs/ac for an average year; 400 lbs/ac for an above average year; -
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:
None -
Perennial plant reproductive capability:
Can be severely impaired for perennial grasses like bush muhly, threeawn, fluffgrass and black grama from severe drought. All desert zinnia plants on site are dead except those in small associated drainage ways.
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