Natural Resources
Conservation Service
Ecological site R040XA108AZ
Limy Fan 10"-13" p.z.
Accessed: 04/16/2024
General information
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.
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): 040X–Sonoran Basin and Range
AZ 40.1 – Upper Sonoran Desert
Elevations range from 2000 to 3200 feet and precipitation averages 10 to 13 inches per year. Vegetation includes saguaro, palo verde, mesquite, creosotebush, triangle bursage, prickly pear, cholla, limberbush, wolfberry, bush muhly, threeawns, ocotillo, and globe mallow. 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
| R040XA102AZ |
Clayey Swale 10"-13" p.z. |
|---|---|
| R040XA112AZ |
Loamy Swale 10"-13" p.z. |
| R040XA115AZ |
Sandy Wash 10"-13" p.z. |
Similar sites
| R041XB206AZ |
Limy Fan 8-12" p.z. |
|---|---|
| R040XB207AZ |
Limy Fan 7"-10" p.z. |
Table 1. Dominant plant species
| Tree |
Not specified |
|---|---|
| Shrub |
(1) larrea tridentata |
| Herbaceous |
(1) muhlenbergia porteri |
Physiographic features
This site occurs in the upper elevations of the Sonoran Desert in southern Arizona. It occurs on alluvial fans, fan terraces and stream terraces.
Table 2. Representative physiographic features
| Landforms |
(1)
Fan
(2) Terrace (3) Alluvial fan |
|---|---|
| Flooding duration | Extremely brief (0.1 to 4 hours) |
| Flooding frequency | Very rare to none |
| Ponding frequency | None |
| Elevation | 1,900 – 3,200 ft |
| Slope | 1 – 5% |
| Aspect | Aspect is not a significant factor |
Climatic features
Precipitation in the sub resource area ranges from 10 to 13 inches in the southern part, along the Mexican border with elevations from about 1900 to 3200 feet. Precipitation in the northern part of the resource area ranges from 11 to 14 inches with elevations from about 1700 to 3500 feet. Winter-summer rainfall ratios range from 40%-60% in the southern portions of the land resource unit, to 50%-50% in the central portions, to 60%-40% in the northern part of the land resource unit. As one moves from east to west in this resource area rains become slightly more unpredictable and variable with Coefficients of Variation of annual rainfall equal to 29% at Tucson and 36% at Carefree. Summer rains fall July through Sept., originate in the Gulf of Mexico, and are convective, usually brief, intense thunderstorms. Cool season moisture tends to be frontal, originating in the Pacific and Gulf of California. This winter precipitation falls in widespread storms with long duration and low intensity. Snow is rare and seldom lasts more than an hour or two. May and June are the driest months of the year. Humidity is generally very low.
Winter temperatures are mild, with very few days recording freezing temperatures in the morning. Summer temperatures are warm to hot, with several days in June and July exceeding 105 degrees F.
Both the spring and the summer growing seasons are equally important for perennial grass, forb and shrub growth. Cool and warm season annual forbs and grasses can be common in their respective seasons with above average rainfall. Perennial forage species can remain green throughout the year with available moisture.
Table 3. Representative climatic features
| Frost-free period (average) | 265 days |
|---|---|
| Freeze-free period (average) | 0 days |
| Precipitation total (average) | 13 in |
Figure 2. Monthly precipitation range
Figure 3. Monthly average minimum and maximum temperature
Influencing water features
There are no water features associated with this site.
Soil features
These soils are deep soils formed in limy, loamy alluvium of mixed origin. They are calcareous throughout. Calcic horizons occur at shallow depths. Plant-soil moisture relationships are fair to good.
Soils mapped on this site include:
SSA-661 Eastern Pinal-Southern Gila Counties MU's Ugyp-505, Whitecliff-505 & 525;
SSA-666 Northwest Cochise County MU's Dudleyville-487 & Agustin-487;
SSA-668 Tucson-Avra Valley area MU's Anthony-AhB, Gila-GbB, Laveen-LaA, LaB, LdB, LeA, LeB, LmB, LrB & TxB, Laveen Varient-LsB, Rillito-ClC, LrB, RdB, ReC & RtB, Tres Hermanos-MtB, RtB, ThB TmB & TwB;
SSA-669 Eastern Pima County MU's Yaqui-86, Sahuarita-72 & 78;
SSA-703 Tohono O'odham area MU's Agustin-60, Chutum-13, Glendale-29 & 30, Pajarito-30 & 47, & Sahuarito-47.
Table 4. Representative soil features
| Surface texture |
(1) Sandy loam (2) Gravelly sandy loam (3) Fine sandy loam |
|---|---|
| Family particle size |
(1) Loamy |
| Drainage class | Well drained |
| Permeability class | Moderately rapid to moderate |
| Soil depth | 60 in |
| Surface fragment cover <=3" | 50% |
| Surface fragment cover >3" | 5% |
| Available water capacity (0-40in) |
5 – 7 in |
| Calcium carbonate equivalent (0-40in) |
5 – 30% |
| Electrical conductivity (0-40in) |
2 mmhos/cm |
| Sodium adsorption ratio (0-40in) |
2 |
| Soil reaction (1:1 water) (0-40in) |
7.8 – 8.4 |
| Subsurface fragment volume <=3" (Depth not specified) |
30% |
| Subsurface fragment volume >3" (Depth not specified) |
2% |
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 the 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 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
Figure 4. State and Transition model, Limy Fan 10-13" pz.
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 text
State 1 submodel, plant communities
State 2 submodel, plant communities
State 3 submodel, plant communities
State 4 submodel, plant communities
State 5 submodel, plant communities
State 6 submodel, plant communities
State 7 submodel, plant communities
State 8 submodel, plant communities
State 1
Historical Climax Plant Community
Community 1.1
Historical Climax Plant Community
The potential plant community is a shrubland dominated by creosotebush. Annual forbs and grasses are very important in the plant community on this site, but fluctuate from nearly nothing in dry years to several hundred pounds per acre in wet years. Cryptogams (algae, lichens, mosses) are also important in the plant communities on this site. With continuous heavy grazing, bush muhly is removed from the plant community and creosotebush increases. Areas of this site mapped in alluvial fan positions are very susceptible to rill and gully erosion.
Figure 5. 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) |
|---|---|---|---|
| Grass/Grasslike | 6 | 100 | 470 |
| Forb | 2 | 150 | 420 |
| Shrub/Vine | 102 | 250 | 390 |
| Tree | 0 | 5 | 25 |
| Total | 110 | 505 | 1305 |
Table 6. Soil surface cover
| Tree basal cover | 0% |
|---|---|
| Shrub/vine/liana basal cover | 1-3% |
| Grass/grasslike basal cover | 0-1% |
| Forb basal cover | 0-1% |
| Non-vascular plants | 0% |
| Biological crusts | 15-35% |
| Litter | 10-80% |
| Surface fragments >0.25" and <=3" | 0-50% |
| Surface fragments >3" | 0-5% |
| Bedrock | 0% |
| Water | 0% |
| Bare ground | 5-70% |
Table 7. Canopy structure (% cover)
| Height Above Ground (ft) | Tree | Shrub/Vine | Grass/ Grasslike |
Forb |
|---|---|---|---|---|
| <0.5 | – | – | 0-25% | 0-50% |
| >0.5 <= 1 | – | 0-1% | 0-10% | 0-15% |
| >1 <= 2 | – | 0-1% | 1-5% | 0-5% |
| >2 <= 4.5 | – | 5-15% | – | – |
| >4.5 <= 13 | 0-1% | 0-5% | – | – |
| >13 <= 40 | 0-1% | – | – | – |
| >40 <= 80 | – | – | – | – |
| >80 <= 120 | – | – | – | – |
| >120 | – | – | – | – |
Figure 6. Plant community growth curve (percent production by month). AZ4013, 40.1 10-13" p.z. other sites. Growth begins in the late winter, goes semi-dormant in the drought period of late May through early July, growth continues in the summer through early fall..
| 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 | 5 | 10 | 20 | 15 | 0 | 5 | 20 | 15 | 5 | 5 | 0 |
State 2
Annuals and desert broom
Community 2.1
Annuals and desert broom
This state occurs after clearing for irrigation and subsequent abandonment. Early stages of plant succession lead to dominance by annual forbs and grasses (both native and non-native). Tumbleweed (Russian thistle) will persist with continued disturbance like disking. Desert broom can invade and may dominate the upper layer of the plant community for many years. This state will persist for several years before other shrubs and desert trees come in and assume dominance.
State 3
Mesquite, grass and shrubs
Community 3.1
Mesquite, grass and shrubs
This state will result from long term rest of areas that were cleared and then abandoned. Without disturbance for 30 or 40 years mesquite will come in with other shrubs like creosote and whitethorn acacia and form an open overstory. Perennial grasses, both native and non-native will dominate the understory especially in areas where water accumulates; the bottom ends of fields, furrows or borders. Annual forbs and grasses (both native and exotic) will fluctuate with climate. This appears to be a stable community without fire or other disturbance like continuous grazing.
State 4
Exotic perennial grasses with natives
Community 4.1
Exotic perennial grasses with natives
This state occurs where exotic perennial grass species like bufflegrass have invaded the native plant community. Bufflegrass fills the niche of native perennial like bush muhly and will even compete with creosotebush on this site.
State 5
Exotic perennial grasses and fire
Community 5.1
Exotic perennial grasses and fire
This community occurs where a native plant community that has been invaded by bufflegrass or fountain grass has burned one or more times. Increasing amounts of exotic perennial grasses leads to more uniform fine fuels. Frequent fires will remove creosotebush and other native shrubs, trees and cacti from the plant community. In areas adjacent to roads and urban areas the risk of repeated fires will increase. As fire frequency increases the dominance of the exotic grasses increase.
State 6
Native plant community with exotic annuals
Community 6.1
Native plant community with exotic annuals
This plant community occurs where the native plant community has been invaded by annuals like schismus, red brome and filaree. These species occupy the niche of the native winter annual forbs and grasses. The exotic annual grasses will fluctuate from nearly nothing in a dry winter to dominance of the understory plant community in a El Nino winter.
State 7
Annuals, half shrubs and fire
Community 7.1
Annuals, half shrubs and fire
This plant community occurs as a result of a single hot season fire. Paloverde, creosotebush and cacti can be severely impacted and may take long periods of time (30-50 years) to recover to pre-fire levels. Perennial and annual grasses and forbs dominate the community for some time until shrubs like bursage, paperflower or desert zinnia can recover. Perennial grasses can recover rapidly if grazing pressure is low and summer rains are sufficient. This plant community can produce more than enough herbaceous fuel from native species of grasses and / or forbs to carry fire in El Nino years or after unusually wet summers. The natural incidence of fire in this MLRA is very low and fires are much more common from man-made ignitions. Areas of the site close to urban zones or along heavily travelled roads and highways will experience a higher rate of fires.
State 8
Annuals and fire
Community 8.1
Annuals and fire
This plant community occurs where the native plant community has burned repeatedly. As fires become more frequent the native shrubs and succulents are removed from the plant community and annuals becomes dominant. In areas of the site near urban areas and along heavily travelled roads this will be a more common occurence due to an increased source of ignitions. This can occur both in areas with only native annuals species present as well as those which have been invaded by schismus and red brome.
Additional community tables
Table 8. Community 1.1 plant community composition
| Group | Common name | Symbol | Scientific name | Annual production (lb/acre) | Foliar cover (%) | |
|---|---|---|---|---|---|---|
|
Grass/Grasslike
|
||||||
| 1 | Dominant suffrutescent grass | 5–100 | ||||
| bush muhly | MUPO2 | Muhlenbergia porteri | 5–100 | – | ||
| 2 | Sub dominant perennial grasses | 0–50 | ||||
| whiplash pappusgrass | PAVA2 | Pappophorum vaginatum | 0–30 | – | ||
| Parish's threeawn | ARPUP5 | Aristida purpurea var. parishii | 0–20 | – | ||
| spike dropseed | SPCO4 | Sporobolus contractus | 0–10 | – | ||
| false Rhodes grass | TRCR9 | Trichloris crinita | 0–10 | – | ||
| 3 | Miscellaneous perennial grasses | 0–20 | ||||
| Parry's grama | BOPA2 | Bouteloua parryi | 0–15 | – | ||
| Rothrock's grama | BORO2 | Bouteloua rothrockii | 0–15 | – | ||
| purple threeawn | ARPU9 | Aristida purpurea | 0–10 | – | ||
| spidergrass | ARTE3 | Aristida ternipes | 0–10 | – | ||
| low woollygrass | DAPU7 | Dasyochloa pulchella | 0–5 | – | ||
| Santa Rita threeawn | ARCAG | Aristida californica var. glabrata | 0–5 | – | ||
| nineawn pappusgrass | ENDE | Enneapogon desvauxii | 0–5 | – | ||
| big sacaton | SPWR2 | Sporobolus wrightii | 0–5 | – | ||
| tobosagrass | PLMU3 | Pleuraphis mutica | 0–1 | – | ||
| plains bristlegrass | SEVU2 | Setaria vulpiseta | 0–1 | – | ||
| sand dropseed | SPCR | Sporobolus cryptandrus | 0–1 | – | ||
| mesa dropseed | SPFL2 | Sporobolus flexuosus | 0–1 | – | ||
| Arizona cottontop | DICA8 | Digitaria californica | 0–1 | – | ||
| 4 | Annual grasses | 1–300 | ||||
| sixweeks grama | BOBA2 | Bouteloua barbata | 0–100 | – | ||
| sixweeks fescue | VUOC | Vulpia octoflora | 0–100 | – | ||
| mucronate sprangeltop | LEPAB | Leptochloa panicea ssp. brachiata | 0–50 | – | ||
| sixweeks threeawn | ARAD | Aristida adscensionis | 0–50 | – | ||
| prairie threeawn | AROL | Aristida oligantha | 0–50 | – | ||
| needle grama | BOAR | Bouteloua aristidoides | 0–50 | – | ||
| Mexican panicgrass | PAHI5 | Panicum hirticaule | 0–25 | – | ||
| Bigelow's bluegrass | POBI | Poa bigelovii | 0–10 | – | ||
| desert lovegrass | ERPEM | Eragrostis pectinacea var. miserrima | 0–10 | – | ||
| tufted lovegrass | ERPEP2 | Eragrostis pectinacea var. pectinacea | 0–10 | – | ||
| Arizona signalgrass | URAR | Urochloa arizonica | 0–5 | – | ||
| canyon cupgrass | ERLE7 | Eriochloa lemmonii | 0–5 | – | ||
| Mexican sprangletop | LEFUU | Leptochloa fusca ssp. uninervia | 0–2 | – | ||
| Arizona brome | BRAR4 | Bromus arizonicus | 0–2 | – | ||
| delicate muhly | MUFR | Muhlenbergia fragilis | 0–1 | – | ||
| littleseed muhly | MUMI | Muhlenbergia microsperma | 0–1 | – | ||
|
Forb
|
||||||
| 5 | Perennial forbs | 1–20 | ||||
| red-gland spurge | CHME5 | Chamaesyce melanadenia | 0–5 | – | ||
| Indian rushpea | HOGL2 | Hoffmannseggia glauca | 0–5 | – | ||
| lacy tansyaster | MAPIP4 | Machaeranthera pinnatifida ssp. pinnatifida var. pinnatifida | 0–5 | – | ||
| Coues' cassia | SECO10 | Senna covesii | 0–5 | – | ||
| desert globemallow | SPAM2 | Sphaeralcea ambigua | 0–5 | – | ||
| dwarf desertpeony | ACNA2 | Acourtia nana | 0–2 | – | ||
| trailing windmills | ALIN | Allionia incarnata | 0–2 | – | ||
| weakleaf bur ragweed | AMCO3 | Ambrosia confertiflora | 0–1 | – | ||
| hairyseed bahia | BAAB | Bahia absinthifolia | 0–1 | – | ||
| desert marigold | BAMU | Baileya multiradiata | 0–1 | – | ||
| hairy five eyes | CHSO | Chamaesaracha sordida | 0–1 | – | ||
| leatherweed | CRPOP | Croton pottsii var. pottsii | 0–1 | – | ||
| fingerleaf gourd | CUDI | Cucurbita digitata | 0–1 | – | ||
| coyote gourd | CUPA | Cucurbita palmata | 0–1 | – | ||
| spreading fleabane | ERDI4 | Erigeron divergens | 0–1 | – | ||
| caliche globemallow | SPLA | Sphaeralcea laxa | 0–1 | – | ||
| pricklyleaf dogweed | THAC | Thymophylla acerosa | 0–1 | – | ||
| Tumamoc globeberry | TUMA | Tumamoca macdougalii | 0–1 | – | ||
| desert tobacco | NIOBO | Nicotiana obtusifolia var. obtusifolia | 0–1 | – | ||
| mesquite mistletoe | PHCA8 | Phoradendron californicum | 0–1 | – | ||
| slender poreleaf | POGR5 | Porophyllum gracile | 0–1 | – | ||
| 6 | Annual forbs | 1–400 | ||||
| Gordon's bladderpod | LEGO | Lesquerella gordonii | 0–100 | – | ||
| Nuttall's povertyweed | MONU | Monolepis nuttalliana | 0–100 | – | ||
| combseed | PECTO | Pectocarya | 0–50 | – | ||
| manybristle chinchweed | PEPA2 | Pectis papposa | 0–50 | – | ||
| shaggyfruit pepperweed | LELA | Lepidium lasiocarpum | 0–50 | – | ||
| California poppy | ESCAM | Eschscholzia californica ssp. mexicana | 0–50 | – | ||
| bristly fiddleneck | AMTE3 | Amsinckia tessellata | 0–50 | – | ||
| wheelscale saltbush | ATEL | Atriplex elegans | 0–50 | – | ||
| woolly plantain | PLPA2 | Plantago patagonica | 0–50 | – | ||
| distant phacelia | PHDI | Phacelia distans | 0–25 | – | ||
| Arizona popcornflower | PLAR | Plagiobothrys arizonicus | 0–25 | – | ||
| desert Indianwheat | PLOV | Plantago ovata | 0–25 | – | ||
| miniature woollystar | ERDI2 | Eriastrum diffusum | 0–25 | – | ||
| California goldfields | LACAC2 | Lasthenia californica ssp. californica | 0–25 | – | ||
| Coulter's lupine | LUSP2 | Lupinus sparsiflorus | 0–25 | – | ||
| foothill deervetch | LOHU2 | Lotus humistratus | 0–20 | – | ||
| cleftleaf wildheliotrope | PHCR | Phacelia crenulata | 0–20 | – | ||
| Texas stork's bill | ERTE13 | Erodium texanum | 0–20 | – | ||
| flatcrown buckwheat | ERDE6 | Eriogonum deflexum | 0–20 | – | ||
| western tansymustard | DEPI | Descurainia pinnata | 0–20 | – | ||
| Coulter's spiderling | BOCO2 | Boerhavia coulteri | 0–20 | – | ||
| cryptantha | CRYPT | Cryptantha | 0–20 | – | ||
| carelessweed | AMPA | Amaranthus palmeri | 0–20 | – | ||
| smallflowered milkvetch | ASNU4 | Astragalus nuttallianus | 0–20 | – | ||
| woolly tidestromia | TILA2 | Tidestromia lanuginosa | 0–20 | – | ||
| woollyhead neststraw | STMI2 | Stylocline micropoides | 0–20 | – | ||
| thelypody | THELY | Thelypodium | 0–15 | – | ||
| Arizona poppy | KAGR | Kallstroemia grandiflora | 0–15 | – | ||
| Arizona phacelia | PHAR13 | Phacelia arizonica | 0–15 | – | ||
| California desertdandelion | MACA6 | Malacothrix californica | 0–15 | – | ||
| slender goldenweed | MAGR10 | Machaeranthera gracilis | 0–15 | – | ||
| mesa tansyaster | MATA | Machaeranthera tagetina | 0–15 | – | ||
| coastal bird's-foot trefoil | LOSAB | Lotus salsuginosus var. brevivexillus | 0–10 | – | ||
| wedgeleaf draba | DRCU | Draba cuneifolia | 0–10 | – | ||
| American wild carrot | DAPU3 | Daucus pusillus | 0–10 | – | ||
| star gilia | GIST | Gilia stellata | 0–10 | – | ||
| yellow tackstem | CAPA7 | Calycoseris parryi | 0–10 | – | ||
| white tackstem | CAWR | Calycoseris wrightii | 0–10 | – | ||
| Esteve's pincushion | CHST | Chaenactis stevioides | 0–10 | – | ||
| sand pygmyweed | CRCOC | Crassula connata var. connata | 0–10 | – | ||
| Coulter's globemallow | SPCO2 | Sphaeralcea coulteri | 0–10 | – | ||
| New Mexico plumeseed | RANE | Rafinesquia neomexicana | 0–5 | – | ||
| sleepy silene | SIAN2 | Silene antirrhina | 0–5 | – | ||
| sand fringepod | THCU | Thysanocarpus curvipes | 0–5 | – | ||
| Louisiana vetch | VILU | Vicia ludoviciana | 0–5 | – | ||
| hairy prairie clover | DAMO | Dalea mollis | 0–5 | – | ||
| white easterbonnets | ANLA7 | Antheropeas lanosum | 0–5 | – | ||
| fringed amaranth | AMFI | Amaranthus fimbriatus | 0–5 | – | ||
| California suncup | CACA32 | Camissonia californica | 0–5 | – | ||
| whitestem blazingstar | MEAL6 | Mentzelia albicaulis | 0–5 | – | ||
| Lindley's silverpuffs | MILI5 | Microseris lindleyi | 0–5 | – | ||
| glandular threadplant | NEGL | Nemacladus glanduliferus | 0–5 | – | ||
| desert evening primrose | OEPR | Oenothera primiveris | 0–5 | – | ||
| Florida pellitory | PAFL3 | Parietaria floridana | 0–2 | – | ||
| green carpetweed | MOVE | Mollugo verticillata | 0–2 | – | ||
| bristly nama | NAHI | Nama hispidum | 0–2 | – | ||
| Mexican fireplant | EUHE4 | Euphorbia heterophylla | 0–2 | – | ||
| hairy desertsunflower | GECA2 | Geraea canescens | 0–2 | – | ||
| brittle spineflower | CHBR | Chorizanthe brevicornu | 0–2 | – | ||
| hoary bowlesia | BOIN3 | Bowlesia incana | 0–2 | – | ||
| hyssopleaf sandmat | CHHY3 | Chamaesyce hyssopifolia | 0–2 | – | ||
| staggerweed | STAR | Stachys arvensis | 0–2 | – | ||
| doubleclaw | PRPA2 | Proboscidea parviflora | 0–2 | – | ||
| bristly scaleseed | SPEC2 | Spermolepis echinata | 0–1 | – | ||
| false carrot | YAMI | Yabea microcarpa | 0–1 | – | ||
| Sonoran sandmat | CHMI7 | Chamaesyce micromera | 0–1 | – | ||
| Chiricahua Mountain sandmat | CHFL3 | Chamaesyce florida | 0–1 | – | ||
| Thurber's buckwheat | ERTH3 | Eriogonum thurberi | 0–1 | – | ||
| California mustard | GULA4 | Guillenia lasiophylla | 0–1 | – | ||
| Palmer's grapplinghook | HAPA7 | Harpagonella palmeri | 0–1 | – | ||
| flatspine stickseed | LAOCO | Lappula occidentalis var. occidentalis | 0–1 | – | ||
| dainty desert hideseed | EUMI2 | Eucrypta micrantha | 0–1 | – | ||
| spring pygmycudweed | EVVE | Evax verna | 0–1 | – | ||
| Abert's buckwheat | ERAB2 | Eriogonum abertianum | 0–1 | – | ||
| Mojave desertstar | MOBE2 | Monoptilon bellioides | 0–1 | – | ||
|
Shrub/Vine
|
||||||
| 7 | Dominant shrub | 100–300 | ||||
| creosote bush | LATRT | Larrea tridentata var. tridentata | 100–300 | – | ||
| 8 | Miscellaneous shrubs | 0–30 | ||||
| whitethorn acacia | ACCO2 | Acacia constricta | 0–20 | – | ||
| Arizona desert-thorn | LYEX | Lycium exsertum | 0–10 | – | ||
| water jacket | LYAN | Lycium andersonii | 0–5 | – | ||
| fourwing saltbush | ATCA2 | Atriplex canescens | 0–5 | – | ||
| soaptree yucca | YUEL | Yucca elata | 0–2 | – | ||
| lotebush | ZIOB | Ziziphus obtusifolia | 0–2 | – | ||
| Warnock's snakewood | COWA | Condalia warnockii | 0–1 | – | ||
| crown of thorns | KOSP | Koeberlinia spinosa | 0–1 | – | ||
| catclaw acacia | ACGR | Acacia greggii | 0–1 | – | ||
| 9 | Half shrubs | 0–30 | ||||
| whitestem paperflower | PSCO2 | Psilostrophe cooperi | 0–15 | – | ||
| desert zinnia | ZIAC | Zinnia acerosa | 1–15 | – | ||
| triangle bur ragweed | AMDE4 | Ambrosia deltoidea | 0–10 | – | ||
| littleleaf ratany | KRER | Krameria erecta | 0–10 | – | ||
| white ratany | KRGR | Krameria grayi | 0–10 | – | ||
| threadleaf snakeweed | GUMI | Gutierrezia microcephala | 0–2 | – | ||
| broom snakeweed | GUSA2 | Gutierrezia sarothrae | 0–1 | – | ||
| burroweed | ISTE2 | Isocoma tenuisecta | 0–1 | – | ||
| 10 | Succulents | 2–30 | ||||
| Christmas cactus | CYLE8 | Cylindropuntia leptocaulis | 1–10 | – | ||
| tulip pricklypear | OPPH | Opuntia phaeacantha | 1–10 | – | ||
| nightblooming cereus | PEGRG | Peniocereus greggii var. greggii | 0–5 | – | ||
| Arizona pencil cholla | CYAR14 | Cylindropuntia arbuscula | 0–5 | – | ||
| devil's cholla | GRKU | Grusonia kunzei | 0–5 | – | ||
| cactus apple | OPEN3 | Opuntia engelmannii | 0–5 | – | ||
| purple pricklypear | OPMA8 | Opuntia macrocentra | 0–2 | – | ||
| candy barrelcactus | FEWI | Ferocactus wislizeni | 0–2 | – | ||
| jumping cholla | CYFU10 | Cylindropuntia fulgida | 0–2 | – | ||
| walkingstick cactus | CYSP8 | Cylindropuntia spinosior | 0–2 | – | ||
| staghorn cholla | CYVE3 | Cylindropuntia versicolor | 0–2 | – | ||
| saguaro | CAGI10 | Carnegiea gigantea | 0–2 | – | ||
| buck-horn cholla | CYAC8 | Cylindropuntia acanthocarpa | 0–1 | – | ||
| Engelmann's hedgehog cactus | ECEN | Echinocereus engelmannii | 0–1 | – | ||
| pinkflower hedgehog cactus | ECFA | Echinocereus fasciculatus | 0–1 | – | ||
| beavertail pricklypear | OPBA2 | Opuntia basilaris | 0–1 | – | ||
|
Tree
|
||||||
| 11 | Trees | 0–25 | ||||
| velvet mesquite | PRVE | Prosopis velutina | 0–25 | – | ||
| blue paloverde | PAFL6 | Parkinsonia florida | 0–5 | – | ||
| yellow paloverde | PAMI5 | Parkinsonia microphylla | 0–5 | – | ||
Interpretations
Animal community
This site is more suitable for seasonal grazing use. The bulk of the forage produced consists of either winter or summer annual grasses and forbs in average or above average rainfall years. Perennial forage species can grow year round with available moisture but are in limited amounts in the plant community. Forage production on the site in dry years is very low. Bush muhly is shrub-like in character and plants supported by creosotebush should be utilized as browse plants.
Vegetative cover and forage diversity are lacking for large desert mammals on this site. It is home mainly to small, burrowing animals and rabbits.
Hydrological functions
The soils on this site are medium textured but with nearly level slopes it is only a fair producer of runoff.
Recreational uses
Hunting, hiking, camping, birdwatching, horseback riding.
Wood products
Very limited mesquite for camp fires and branding fires.
Other products
Creosotebush for medicinal uses. Prickly pear and cholla fruits.
Supporting information
Inventory data references
Range 417s include 1 in good condition
Type locality
| Location 1: Pima County, AZ | |
|---|---|
| Township/Range/Section | T17S R15E S31 |
| General legal description | Tucson FO - Santa Rita Experimental Range NE 1/4 of sec. 31 |
| Location 2: Pima County, AZ | |
| Township/Range/Section | T9S R2E S20 |
| General legal description | Sells FO - Headwaters of Vekol Valley |
| Location 3: Pima County, AZ | |
| Township/Range/Section | T16S R15E S14 |
| General legal description | Pima County Fairgrounds, fenced in 1975. |
Contributors
Dan Robinett
Larry D. Ellicott
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) | Dave Womack, Dan Robinett, Emilio Carrillo |
|---|---|
| Contact for lead author | NRCS Tucson Area Office |
| Date | 03/08/2005 |
| Approved by | S. Cassady |
| Approval date | |
| Composition (Indicators 10 and 12) based on | Annual Production |
Indicators
-
Number and extent of rills:
none -
Presence of water flow patterns:
Water flow patterns are common on this site covering 10-15% of the area. -
Number and height of erosional pedestals or terracettes:
Pedestals are uncommon on grasses and gravels. Terracettes aer uncommon. Mounds ae common on shrubs like creosote bush. -
Bare ground from Ecological Site Description or other studies (rock, litter, lichen, moss, plant canopy are not bare ground):
Bare ground on this site is 25-40%. -
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):
Herbaceous litter moves only in water flow paths 10-15 feet and is deposited in terracettes at curves in flow paths. Woody litter remains in place under shrub canopies. -
Soil surface (top few mm) resistance to erosion (stability values are averages - most sites will show a range of values):
Expect ratings of 4-6 under shrub and grass canopies, and 1-3 in openings. High gravel/cobble cover provides good resistance to erosion. -
Soil surface structure and SOM content (include type of structure and A-horizon color and thickness):
Thin platy structure from rain drop impact to weak granular; 7.5-10YR5-6/5-6 dry; 7.5-10YR4/4-6 moist; thickness to 4 inches -
Effect of community phase composition (relative proportion of different functional groups) and spatial distribution on infiltration and runoff:
large shrubs (creosote #1, whitethorn #2, mesquite #3) 15-20% canopy cover; shrublike grasses (bush muhly) have a 2-5% canopy cover, sub-shrubs including desert zinnia, burroweed, and paper flower have a 2-5% canopy cover and succulents like prickly pear, agave, and barrel cactus have a 1-2% canopy cover. -
Presence and thickness of compaction layer (usually none; describe soil profile features which may be mistaken for compaction on this site):
Soil surface (0.25-0.5 inch) has a platy structure due to overland water flow and some raindrop impact. There is no subsurface soil compaction. -
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:
large shrubs > shrub-like grasses > sub-shrubs > annual forbs and grasses > other perennial grasses > succulents > perennial forbs > cryptogams. (In El Nino years, the production of annual forbs can exceed all other plant species.)Sub-dominant:
Other:
Additional:
-
Amount of plant mortality and decadence (include which functional groups are expected to show mortality or decadence):
Severe drought last several years resulting in 90-100% mortality on short perennial grasses (threeawns), 50% mortality on bush muhly, 75% mortality on sub-shrubs and 10-15% mortality on large shrubs. -
Average percent litter cover (%) and depth ( in):
-
Expected annual annual-production (this is TOTAL above-ground annual-production, not just forage annual-production):
110 lbs/ac unfavorable precipitation; 505 lbs/ac normal precipitation; 1305 lbs/ac 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:
schismus, filaree, malta srarthistle -
Perennial plant reproductive capability:
not impaired for shrubs, drought impaired for perennial grasses and forbs.
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The Ecosystem Dynamics Interpretive Tool is an information system framework developed by the USDA-ARS Jornada Experimental Range, USDA Natural Resources Conservation Service, and New Mexico State University.
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