Natural Resources
Conservation Service
Ecological site R040XA116AZ
Sandy Upland 10"-13" p.z.
Accessed: 12/22/2024
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.
Table 1. Dominant plant species
| Tree |
(1) Parkinsonia microphylla |
|---|---|
| Shrub |
(1) Hymenoclea monogyra |
| Herbaceous |
(1) Muhlenbergia porteri |
Physiographic features
This site occurs in the upper elevations of the Sonoran Desert in southern Arizona. Slopes are mainly from 1 to 3%, but can range as high as 10%.
Table 2. Representative physiographic features
| Landforms |
(1)
Fan
(2) Terrace (3) Stream terrace |
|---|---|
| Elevation | 579 – 975 m |
| Slope | 1 – 10% |
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) | 330 mm |
Figure 2. Monthly precipitation range
Figure 3. Monthly average minimum and maximum temperature
Influencing water features
Soil features
These are deep soils which have formed in very recent sandy, gravelly alluvium of mixed origin. They are sandy throughout to at least moderate depths (30 inches). Plant-soil moisture relationships are good. Soils may be mild calcareous in the surface.
Soils mapped on this site include: in
SSA-668 Tucson-Avra Valley area MU's Cowan-CsA, CsB & CvB and Vinton-VsB;
SSA-703 Tohono O'odham area MU Arizo-4.
Table 4. Representative soil features
| Surface texture |
(1) Very gravelly sandy loam (2) Very gravelly loamy sand |
|---|---|
| Family particle size |
(1) Sandy |
| Drainage class | Somewhat excessively drained |
| Permeability class | Very rapid |
| Soil depth | 152 cm |
| Surface fragment cover <=3" | 20 – 70% |
| Surface fragment cover >3" | 0 – 1% |
| Available water capacity (0-101.6cm) |
5.08 – 12.7 cm |
| Calcium carbonate equivalent (0-101.6cm) |
0 – 5% |
| 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) |
35 – 65% |
| 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 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
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Ecosystem states
State 1 submodel, plant communities
State 1
Historical Climax Plant Community
Community 1.1
Historical Climax Plant Community
The potential plant community on this site is a diverse mixture of large and small shrubs, trees and perennial grasses and forbs. The major perennial grass and forb species tend to grow in patches and are not well dispersed throughout the community although on a larger scale, the patches are. The aspect is shrubland. With continuous, heavy grazing, perennial grass species are removed from the plant community. Shrubs like triangle bursage, white brittlebush, burroweed, and white burrobush can inrease to dominate the understory. Trees grow to near maximum size on these deep, course textured soils. Up to 10% tree canopy is important on this site to provide diversity in the plant community. Even without herbaceous cover, these soils produce very little runoff and have very low water erosion rates. Most of these soils have enough course fragments that they are not subject to wind erosion but in places blowing can occur if the woody cover is removed or disturbed.
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 | 328 | – | 401 |
| Shrub/Vine | 230 | – | 279 |
| Forb | 37 | – | 108 |
| Tree | 26 | – | 49 |
| Total | 621 | – | 837 |
Additional community tables
Table 6. Community 1.1 plant community composition
| Group | Common name | Symbol | Scientific name | Annual production (kg/hectare) | Foliar cover (%) | |
|---|---|---|---|---|---|---|
|
Grass/Grasslike
|
||||||
| 1 | 56–73 | |||||
| bush muhly | MUPO2 | Muhlenbergia porteri | 34–45 | – | ||
| black grama | BOER4 | Bouteloua eriopoda | 22–28 | – | ||
| 2 | 56–73 | |||||
| Santa Rita threeawn | ARCAG | Aristida californica var. glabrata | 27–37 | – | ||
| purple threeawn | ARPU9 | Aristida purpurea | 28–36 | – | ||
| 3 | 3–18 | |||||
| sand dropseed | SPCR | Sporobolus cryptandrus | 2–13 | – | ||
| mesa dropseed | SPFL2 | Sporobolus flexuosus | 1–4 | – | ||
| 4 | 3–18 | |||||
| blue threeawn | ARPUN | Aristida purpurea var. nealleyi | 1–2 | – | ||
| Parish's threeawn | ARPUP5 | Aristida purpurea var. parishii | 1–2 | – | ||
| spidergrass | ARTE3 | Aristida ternipes | 1–2 | – | ||
| spidergrass | ARTEG | Aristida ternipes var. gentilis | 0–1 | – | ||
| cane bluestem | BOBA3 | Bothriochloa barbinodis | 0–1 | – | ||
| sideoats grama | BOCU | Bouteloua curtipendula | 0–1 | – | ||
| Arizona cottontop | DICA8 | Digitaria californica | 0–1 | – | ||
| squirreltail | ELELE | Elymus elymoides ssp. elymoides | 0–1 | – | ||
| tanglehead | HECO10 | Heteropogon contortus | 0–1 | – | ||
| big galleta | PLRI3 | Pleuraphis rigida | 0–1 | – | ||
| plains bristlegrass | SEVU2 | Setaria vulpiseta | 0–1 | – | ||
| spike dropseed | SPCO4 | Sporobolus contractus | 0–1 | – | ||
| 5 | 37–55 | |||||
| Rothrock's grama | BORO2 | Bouteloua rothrockii | 6–11 | – | ||
| needle grama | BOAR | Bouteloua aristidoides | 1–4 | – | ||
| sixweeks threeawn | ARAD | Aristida adscensionis | 1–3 | – | ||
| Arizona brome | BRAR4 | Bromus arizonicus | 1–2 | – | ||
| villous lipfern | CHVI | Cheilanthes villosa | 1–2 | – | ||
| low woollygrass | DAPU7 | Dasyochloa pulchella | 1–2 | – | ||
| nineawn pappusgrass | ENDE | Enneapogon desvauxii | 1–2 | – | ||
| canyon cupgrass | ERLE7 | Eriochloa lemmonii | 1–2 | – | ||
| desert lovegrass | ERPEM | Eragrostis pectinacea var. miserrima | 1–2 | – | ||
| tufted lovegrass | ERPEP2 | Eragrostis pectinacea var. pectinacea | 1–2 | – | ||
| mucronate sprangeltop | LEPAB | Leptochloa panicea ssp. brachiata | 1–2 | – | ||
| delicate muhly | MUFR | Muhlenbergia fragilis | 1–2 | – | ||
| littleseed muhly | MUMI | Muhlenbergia microsperma | 1–2 | – | ||
| witchgrass | PACA6 | Panicum capillare | 1–2 | – | ||
| Bigelow's bluegrass | POBI | Poa bigelovii | 1–2 | – | ||
| Arizona signalgrass | URAR | Urochloa arizonica | 1–2 | – | ||
| sixweeks fescue | VUOC | Vulpia octoflora | 1–2 | – | ||
| sixweeks grama | BOBA2 | Bouteloua barbata | 1–2 | – | ||
|
Forb
|
||||||
| 6 | 3–17 | |||||
| desert globemallow | SPAM2 | Sphaeralcea ambigua | 1–6 | – | ||
| trailing windmills | ALIN | Allionia incarnata | 1–2 | – | ||
| Yuma silverbush | ARSE7 | Argythamnia serrata | 0–1 | – | ||
| desert marigold | BAMU | Baileya multiradiata | 0–1 | – | ||
| Coulter's spiderling | BOCO2 | Boerhavia coulteri | 0–1 | – | ||
| whitemargin sandmat | CHAL11 | Chamaesyce albomarginata | 0–1 | – | ||
| lacy tansyaster | MAPIP4 | Machaeranthera pinnatifida ssp. pinnatifida var. pinnatifida | 0–1 | – | ||
| desert tobacco | NIOBO | Nicotiana obtusifolia var. obtusifolia | 0–1 | – | ||
| canaigre dock | RUHY | Rumex hymenosepalus | 0–1 | – | ||
| smooth threadleaf ragwort | SEFLM | Senecio flaccidus var. monoensis | 0–1 | – | ||
| 7 | 0–56 | |||||
| desert sand verbena | ABVI | Abronia villosa | 0–1 | – | ||
| brownfoot | ACWR5 | Acourtia wrightii | 0–1 | – | ||
| weakleaf bur ragweed | AMCO3 | Ambrosia confertiflora | 0–1 | – | ||
| carelessweed | AMPA | Amaranthus palmeri | 0–1 | – | ||
| bristly fiddleneck | AMTE3 | Amsinckia tessellata | 0–1 | – | ||
| aster | ASTER | Aster | 0–1 | – | ||
| milkvetch | ASTRA | Astragalus | 0–1 | – | ||
| Coulter's spiderling | BOCO2 | Boerhavia coulteri | 0–1 | – | ||
| hoary bowlesia | BOIN3 | Bowlesia incana | 0–1 | – | ||
| Tucson Mountain spiderling | BOME | Boerhavia megaptera | 0–1 | – | ||
| Arizona wrightwort | CAAR7 | Carlowrightia arizonica | 0–1 | – | ||
| hyssopleaf sandmat | CHHY3 | Chamaesyce hyssopifolia | 0–1 | – | ||
| New Mexico thistle | CINE | Cirsium neomexicanum | 0–1 | – | ||
| cryptantha | CRYPT | Cryptantha | 0–1 | – | ||
| coyote gourd | CUPA | Cucurbita palmata | 0–1 | – | ||
| pricklyburr | DAIN2 | Datura inoxia | 0–1 | – | ||
| American wild carrot | DAPU3 | Daucus pusillus | 0–1 | – | ||
| western tansymustard | DEPI | Descurainia pinnata | 0–1 | – | ||
| Palmer's spectaclepod | DICA31 | Dimorphocarpa candicans | 0–1 | – | ||
| flatcrown buckwheat | ERDE6 | Eriogonum deflexum | 0–1 | – | ||
| miniature woollystar | ERDI2 | Eriastrum diffusum | 0–1 | – | ||
| spreading fleabane | ERDI4 | Erigeron divergens | 0–1 | – | ||
| buckwheat | ERIOG | Eriogonum | 0–1 | – | ||
| Texas stork's bill | ERTE13 | Erodium texanum | 0–1 | – | ||
| California poppy | ESCAM | Eschscholzia californica ssp. mexicana | 0–1 | – | ||
| Mexican fireplant | EUHE4 | Euphorbia heterophylla | 0–1 | – | ||
| hairy desertsunflower | GECA2 | Geraea canescens | 0–1 | – | ||
| Arizona poppy | KAGR | Kallstroemia grandiflora | 0–1 | – | ||
| Gordon's bladderpod | LEGO | Lesquerella gordonii | 0–1 | – | ||
| shaggyfruit pepperweed | LELA | Lepidium lasiocarpum | 0–1 | – | ||
| coastal bird's-foot trefoil | LOSAB | Lotus salsuginosus var. brevivexillus | 0–1 | – | ||
| Coulter's lupine | LUSP2 | Lupinus sparsiflorus | 0–1 | – | ||
| green carpetweed | MOVE | Mollugo verticillata | 0–1 | – | ||
| evening primrose | OENOT | Oenothera | 0–1 | – | ||
| combseed | PECTO | Pectocarya | 0–1 | – | ||
| manybristle chinchweed | PEPA2 | Pectis papposa | 0–1 | – | ||
| phacelia | PHACE | Phacelia | 0–1 | – | ||
| slimjim bean | PHFI3 | Phaseolus filiformis | 0–1 | – | ||
| Arizona popcornflower | PLAR | Plagiobothrys arizonicus | 0–1 | – | ||
| desert Indianwheat | PLOV | Plantago ovata | 0–1 | – | ||
| purslane | PORTU | Portulaca | 0–1 | – | ||
| doubleclaw | PRPA2 | Proboscidea parviflora | 0–1 | – | ||
| twinleaf senna | SEBA3 | Senna bauhinioides | 0–1 | – | ||
| Coues' cassia | SECO10 | Senna covesii | 0–1 | – | ||
| ragwort | SENEC | Senecio | 0–1 | – | ||
| sleepy silene | SIAN2 | Silene antirrhina | 0–1 | – | ||
| Coulter's globemallow | SPCO2 | Sphaeralcea coulteri | 0–1 | – | ||
| brownplume wirelettuce | STPA4 | Stephanomeria pauciflora | 0–1 | – | ||
| woolly tidestromia | TILA2 | Tidestromia lanuginosa | 0–1 | – | ||
|
Tree
|
||||||
| 8 | 62–112 | |||||
| yellow paloverde | PAMI5 | Parkinsonia microphylla | 34–56 | – | ||
| desert ironwood | OLTE | Olneya tesota | 11–22 | – | ||
| blue paloverde | PAFL6 | Parkinsonia florida | 11–22 | – | ||
| honey mesquite | PRGLG | Prosopis glandulosa var. glandulosa | 6–11 | – | ||
|
Shrub/Vine
|
||||||
| 9 | 34–73 | |||||
| spiny hackberry | CEEH | Celtis ehrenbergiana | 17–39 | – | ||
| catclaw acacia | ACGR | Acacia greggii | 11–22 | – | ||
| water jacket | LYAN | Lycium andersonii | 6–11 | – | ||
| 10 | 0–34 | |||||
| creosote bush | LATRT | Larrea tridentata var. tridentata | 6–17 | – | ||
| fourwing saltbush | ATCA2 | Atriplex canescens | 0–9 | – | ||
| longleaf jointfir | EPTR | Ephedra trifurca | 0–8 | – | ||
| 11 | 11–34 | |||||
| burrobrush | HYSA | Hymenoclea salsola | 6–15 | – | ||
| triangle bur ragweed | AMDE4 | Ambrosia deltoidea | 6–13 | – | ||
| whitestem paperflower | PSCO2 | Psilostrophe cooperi | 1–6 | – | ||
| burroweed | ISTE2 | Isocoma tenuisecta | 1–2 | – | ||
| 12 | 34–73 | |||||
| shortleaf baccharis | BABR | Baccharis brachyphylla | 17–28 | – | ||
| brittlebush | ENFA | Encelia farinosa | 11–17 | – | ||
| desert zinnia | ZIAC | Zinnia acerosa | 11–17 | – | ||
| toothleaf goldeneye | VIDE3 | Viguiera dentata | 1–6 | – | ||
| fairyduster | CAER | Calliandra eriophylla | 1–6 | – | ||
| Thurber's penstemon | PETH3 | Penstemon thurberi | 1–2 | – | ||
| 13 | 6–45 | |||||
| slender janusia | JAGR | Janusia gracilis | 3–6 | – | ||
| slender poreleaf | POGR5 | Porophyllum gracile | 3–6 | – | ||
| littleleaf ratany | KRER | Krameria erecta | 3–6 | – | ||
| jojoba | SICH | Simmondsia chinensis | 1–2 | – | ||
| Jerusalem thorn | PAAC3 | Parkinsonia aculeata | 1–2 | – | ||
| beloperone | JUCA8 | Justicia californica | 1–2 | – | ||
| whitethorn acacia | ACCO2 | Acacia constricta | 1–2 | – | ||
| ambrosia leaf bur ragweed | AMAM2 | Ambrosia ambrosioides | 1–2 | – | ||
| Thurber's desert honeysuckle | ANTH2 | Anisacanthus thurberi | 1–2 | – | ||
| Coulter's brickellbush | BRCO | Brickellia coulteri | 1–2 | – | ||
| ocotillo | FOSP2 | Fouquieria splendens | 1–2 | – | ||
| holywood | GUSA | Guaiacum sanctum | 1–2 | – | ||
| sangre de cristo | JACA2 | Jatropha cardiophylla | 0–1 | – | ||
| San Felipe dogweed | ADPO | Adenophyllum porophylloides | 0–1 | – | ||
| American threefold | TRCA8 | Trixis californica | 0–1 | – | ||
| soaptree yucca | YUEL | Yucca elata | 0–1 | – | ||
| lotebush | ZIOB | Ziziphus obtusifolia | 0–1 | – | ||
| desert-thorn | LYCIU | Lycium | 0–1 | – | ||
| Arizona desert-thorn | LYEX | Lycium exsertum | 0–1 | – | ||
| 14 | 6–34 | |||||
| Engelmann's hedgehog cactus | ECEN | Echinocereus engelmannii | 1–2 | – | ||
| candy barrelcactus | FEWI | Ferocactus wislizeni | 1–2 | – | ||
| limestone adderstongue | OPEN | Ophioglossum engelmannii | 0–1 | – | ||
Interpretations
Animal community
The plant community on this site is suitable for grazing by all classes of cattle in any season. Forage species grow year round with available moisture. Shallow rooted grasses are severely affected by drought on this site. Management should be designed to maintain deeper rooted grasses like bush muhly, and black grama and palatable shrubs like fourwing saltbush, shortleaf baccharis, desert zinnia, and goldeneye on the site. The plant community on this site provides adequate nutrition for livestock throughout the year.
Water developments are very important to wildlife species on this site. This site is a host to a great variety of burrowing, desert mammals, and reptiles. Vegetation structure, cover and forage diversity are very good on this site and allow for diverse wildlife including the large mammals.
Supporting information
Type locality
| Location 1: Pima County, AZ | |
|---|---|
| Township/Range/Section | T8S R12E S8 |
| General legal description | Tucson Field Office - Tom Mix Highway ROW |
| Location 2: Pima County, AZ | |
| Township/Range/Section | T15S R6E S15 |
| General legal description | Sells Field Office - Shuck Toak Dist. |
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 present due to high infiltration rates. -
Presence of water flow patterns:
Water flow patterns are uncommon due to high infiltration rates. -
Number and height of erosional pedestals or terracettes:
All shrubs have symmetrical mounds 2-5 inches tall formed by combined action of splash, erosion and rodents. There are no pedestals on rock or gravel fragments and no terracettes are present. -
Bare ground from Ecological Site Description or other studies (rock, litter, lichen, moss, plant canopy are not bare ground):
50-60% -
Number of gullies and erosion associated with gullies:
noen -
Extent of wind scoured, blowouts and/or depositional areas:
Minor evidence of soil movement by wind. -
Amount of litter movement (describe size and distance expected to travel):
Herbaceous litter can move by wind. Woody litter remains under shrub canopies. -
Soil surface (top few mm) resistance to erosion (stability values are averages - most sites will show a range of values):
Soil surface resistance to erosion is good under shrub canopies to moderate in interspaces due to high infiltration rates. -
Soil surface structure and SOM content (include type of structure and A-horizon color and thickness):
Weak thin platy to single grain; 7.5-10YR5/6 dry, 7.5-10YR4/4 Moist, to 18 inches thick. -
Effect of community phase composition (relative proportion of different functional groups) and spatial distribution on infiltration and runoff:
Canopy 15-25%. Herbaceous litter is present in some years and absent in others. Large shrubs with large coppice mounds with high infiltration rates. Subshrubs with small mounds with high infiltration rates. -
Presence and thickness of compaction layer (usually none; describe soil profile features which may be mistaken for compaction on this site):
None -
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 = shrubs & trees > winter annuals > summer annuals > succulents = perennial forbsSub-dominant:
Other:
Additional:
-
Amount of plant mortality and decadence (include which functional groups are expected to show mortality or decadence):
0-50% canopy mortality, 90-100% mortality on perennial grasses. -
Average percent litter cover (%) and depth ( in):
Herbaceous litter is not persistent on the site. -
Expected annual annual-production (this is TOTAL above-ground annual-production, not just forage annual-production):
554 lbs/ac unfavorable precipitation; 650 lbs/ac normal precipitation; 747 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:
triangle bursage, white brittlebush, borroweed, bufflegrass -
Perennial plant reproductive capability:
Not impaired for shrubs, drought impaired for perennial grasses and forbs.
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