Natural Resources
Conservation Service
Ecological site R040XB206AZ
Shallow Hills 7"-10" 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 40.2 – Middle Sonoran Desert
Elevations range from 1200 to 2000 feet and precipitation averages 7 to 10 inches per year. Vegetation includes saguaro, palo verde, creosotebush, triangle bursage, brittlebush, prickly pear, cholla, desert saltbush, wolfberry bush muhly, threeawns, and big galleta. The soil temperature regime is hyperthermic 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) Ambrosia deltoidea |
| Herbaceous |
(1) Muhlenbergia porteri |
Physiographic features
This site occurs on hillslopes and ridgetops. Slopes range from 15 to 65%. Elevations are from 1000 to 2500 feet. Slope aspect is site differentiating at elevations near land resource area boundaries.
Table 2. Representative physiographic features
| Landforms |
(1)
Hill
(2) Ridge |
|---|---|
| Elevation | 1,000 – 2,500 ft |
| Slope | 15 – 65% |
Climatic features
Precipitation in the sub-resource area ranges from 7 to 10 inches. Elevations range from 900 to 2050 feet. Winter-summer rainfall ratios range from 40% to 60% in the southern part along the international boundary, to 60% to 40% in the central and northern parts of the sub-resource area. As one moves from east to west in this resource area rains become more unpredictable and variable with Coefficients of Variation of annual rainfall equal to 38% at Florence and 46% at Aguila. Summer rains fall July- September, originate in the Gulf of Mexico, and are convective, usually brief, intense thunderstorms. Summer precipitation is extremely erratic and undependable in this area. Cool season moisture tends to be frontal, originates in the Pacific and Gulf of California, and falls in widespread storms with long duration and low intensity. This is the dependable moisture supply for vegetation in the area. Snow is very rare and usually melts on contact. May-June is the driest time of the year. Humidity is very low.
Winter temperatures are very mild with very few days recording freezing for short periods of time. Summertime temperatures are hot to very hot with many days in June-July exceeding 105 degrees F. Frost-free days range from 280 at stations in major river valleys with cold air drainage to 320 to 350 days at upland stations.
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) | 350 days |
|---|---|
| Freeze-free period (average) | 0 days |
| Precipitation total (average) | 10 in |
Figure 2. Monthly precipitation range
Figure 3. Monthly average minimum and maximum temperature
Influencing water features
Soil features
These are shallow soils formed on acid igneous materials; granite and rhyolite, or on quartzite, arkose, shist, and gneiss. Parent material includes schist & gneiss. Bedrock is usually slightly weathered into grus material at the soil juncture. They are non-calcareous, coarse textured and have well developed covers of gravels and cobbles. Bedrock usually has some lime in the fractures. Large areas of rock outcrop and boulders occur intermingled with soil areas. Outcrops can be as high as 25% of the area. Plant-soil moisture relationships are fair.
Soils mapped on this site include: in
SSA-645 Aguila-Carefree area MU's Quilotosa & Vaiva-100;
SSA-653 Gila Bend-Ajo area MU Quilotosa-54;
SSA-658 Gila River Indian Reservation MU's Quilotosa & Vaiva-27;
SSA-703 Tohono O'odham area MU's Chiuchu-12, Gachado non STV phase & Lomitas non calcareous-23, Quilotosa & Vaiva-51.
Table 4. Representative soil features
| Surface texture |
(1) Gravelly sandy loam (2) Very gravelly loam |
|---|---|
| Family particle size |
(1) Loamy |
| Drainage class | Well drained |
| Permeability class | Moderately slow to moderately rapid |
| Soil depth | 4 – 20 in |
| Surface fragment cover <=3" | 35 – 65% |
| Surface fragment cover >3" | 1 – 10% |
| Available water capacity (0-40in) |
0.2 – 1.6 in |
| Calcium carbonate equivalent (0-40in) |
1 – 10% |
| Electrical conductivity (0-40in) |
Not specified |
| Sodium adsorption ratio (0-40in) |
Not specified |
| Soil reaction (1:1 water) (0-40in) |
7.4 – 8.4 |
| Subsurface fragment volume <=3" (Depth not specified) |
35 – 65% |
| Subsurface fragment volume >3" (Depth not specified) |
1 – 10% |
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 is a diverse mixture of desert trees, shrubs, and cacti. The aspect is shrubland. Continuous, heavy grazing removes the small percentage of perennial grasses and forbs from the plant community. Cobble and gravel covers are continuous and average over 90%. Basal cover of perennial plants average 1% and bare ground averages 7%. Cryptogam cover is lacking or very low due to extensive gravel covers. Plant populations of major species range from 500 to 1500 plants per acre for triangle bursage; 50 to 150 trees per acre for paloverde and ironwood and 1 to 50 plants per acre for saguaro. In the northern part of this land resource sub-area, introduced cool season annual grasses; red brome and schismus have invaded native plant communities and have reduced production of the native shrubs significantly, especially on cooler, northern exposures. Club moss and ferns occur only in trace amounts on the northern aspects. Teddy bear cholla predominates on south aspects and buckhorn cholla and prickley pear on the north aspects.
Figure 4. Annual production by plant type (representative values) or group (midpoint values)
Table 5. Annual production by plant type
| Plant type | Low (lb/acre) |
Representative value (lb/acre) |
High (lb/acre) |
|---|---|---|---|
| Shrub/Vine | 350 | – | 450 |
| Forb | 25 | – | 100 |
| Grass/Grasslike | 25 | – | 75 |
| Total | 400 | – | 625 |
Additional community tables
Table 6. Community 1.1 plant community composition
| Group | Common name | Symbol | Scientific name | Annual production (lb/acre) | Foliar cover (%) | |
|---|---|---|---|---|---|---|
|
Grass/Grasslike
|
||||||
| 1 | 10–25 | |||||
| bush muhly | MUPO2 | Muhlenbergia porteri | 0–5 | – | ||
| Parish's threeawn | ARPUP5 | Aristida purpurea var. parishii | 0–3 | – | ||
| purple threeawn | ARPU9 | Aristida purpurea | 0–3 | – | ||
| big galleta | PLRI3 | Pleuraphis rigida | 0–2 | – | ||
| slim tridens | TRMU | Tridens muticus | 0–2 | – | ||
| blue threeawn | ARPUN | Aristida purpurea var. nealleyi | 0–2 | – | ||
| Wright's threeawn | ARPUW | Aristida purpurea var. wrightii | 0–1 | – | ||
| spidergrass | ARTE3 | Aristida ternipes | 0–1 | – | ||
| spidergrass | ARTEG | Aristida ternipes var. gentilis | 0–1 | – | ||
| low woollygrass | DAPU7 | Dasyochloa pulchella | 0–1 | – | ||
| Arizona cottontop | DICA8 | Digitaria californica | 0–1 | – | ||
| nineawn pappusgrass | ENDE | Enneapogon desvauxii | 0–1 | – | ||
| tanglehead | HECO10 | Heteropogon contortus | 0–1 | – | ||
| Fendler's threeawn | ARPUF | Aristida purpurea var. fendleriana | 0–1 | – | ||
| 2 | Annuals | 5–50 | ||||
| sixweeks fescue | VUOC | Vulpia octoflora | 0–10 | – | ||
| Eastwood fescue | VUMIC | Vulpia microstachys var. ciliata | 0–5 | – | ||
| Pacific fescue | VUMIP | Vulpia microstachys var. pauciflora | 0–5 | – | ||
| sixweeks threeawn | ARAD | Aristida adscensionis | 0–5 | – | ||
| prairie threeawn | AROL | Aristida oligantha | 0–5 | – | ||
| needle grama | BOAR | Bouteloua aristidoides | 0–5 | – | ||
| sixweeks grama | BOBA2 | Bouteloua barbata | 0–5 | – | ||
| Rothrock's grama | BORO2 | Bouteloua rothrockii | 0–5 | – | ||
| Arizona brome | BRAR4 | Bromus arizonicus | 0–1 | – | ||
| Mexican sprangletop | LEFUU | Leptochloa fusca ssp. uninervia | 0–1 | – | ||
| mucronate sprangletop | LEPA6 | Leptochloa panicea | 0–1 | – | ||
| delicate muhly | MUFR | Muhlenbergia fragilis | 0–1 | – | ||
| littleseed muhly | MUMI | Muhlenbergia microsperma | 0–1 | – | ||
| witchgrass | PACA6 | Panicum capillare | 0–1 | – | ||
| Bigelow's bluegrass | POBI | Poa bigelovii | 0–1 | – | ||
|
Forb
|
||||||
| 3 | 10–25 | |||||
| desert globemallow | SPAM2 | Sphaeralcea ambigua | 0–5 | – | ||
| brownplume wirelettuce | STPA4 | Stephanomeria pauciflora | 0–3 | – | ||
| desert trumpet | ERIN4 | Eriogonum inflatum | 0–3 | – | ||
| narrowleaf silverbush | ARLA12 | Argythamnia lanceolata | 0–3 | – | ||
| slender poreleaf | POGR5 | Porophyllum gracile | 0–3 | – | ||
| slender janusia | JAGR | Janusia gracilis | 0–2 | – | ||
| lacy tansyaster | MAPIP4 | Machaeranthera pinnatifida ssp. pinnatifida var. pinnatifida | 0–1 | – | ||
| rough menodora | MESC | Menodora scabra | 0–1 | – | ||
| New Mexico silverbush | ARNE2 | Argythamnia neomexicana | 0–1 | – | ||
| whitemargin sandmat | CHAL11 | Chamaesyce albomarginata | 0–1 | – | ||
| California fagonbush | FALA | Fagonia laevis | 0–1 | – | ||
| desert rosemallow | HICO | Hibiscus coulteri | 0–1 | – | ||
| Newberry's velvetmallow | HONE | Horsfordia newberryi | 0–1 | – | ||
| poreleaf dogweed | ADPO2 | Adenophyllum porophyllum | 0–1 | – | ||
| 4 | 5–75 | |||||
| desert Indianwheat | PLOV | Plantago ovata | 0–10 | – | ||
| combseed | PECTO | Pectocarya | 0–5 | – | ||
| common fiddleneck | AMMEI2 | Amsinckia menziesii var. intermedia | 0–5 | – | ||
| green carpetweed | MOVE | Mollugo verticillata | 0–3 | – | ||
| globemallow | SPHAE | Sphaeralcea | 0–3 | – | ||
| woolly tidestromia | TILA2 | Tidestromia lanuginosa | 0–1 | – | ||
| bristly nama | NAHI | Nama hispidum | 0–1 | – | ||
| glandular threadplant | NEGL | Nemacladus glanduliferus | 0–1 | – | ||
| desert tobacco | NIOB | Nicotiana obtusifolia | 0–1 | – | ||
| cloak fern | NOTHO | Notholaena | 0–1 | – | ||
| evening primrose | OENOT | Oenothera | 0–1 | – | ||
| Florida pellitory | PAFL3 | Parietaria floridana | 0–1 | – | ||
| Emory's rockdaisy | PEEM | Perityle emoryi | 0–1 | – | ||
| cliffbrake | PELLA | Pellaea | 0–1 | – | ||
| manybristle chinchweed | PEPA2 | Pectis papposa | 0–1 | – | ||
| phacelia | PHACE | Phacelia | 0–1 | – | ||
| brownfoot | ACWR5 | Acourtia wrightii | 0–1 | – | ||
| trailing windmills | ALIN | Allionia incarnata | 0–1 | – | ||
| New Mexico plumeseed | RANE | Rafinesquia neomexicana | 0–1 | – | ||
| chia | SACO6 | Salvia columbariae | 0–1 | – | ||
| Arizona spikemoss | SEAR2 | Selaginella arizonica | 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 | – | ||
| carelessweed | AMPA | Amaranthus palmeri | 0–1 | – | ||
| rockcress | ARABI2 | Arabis | 0–1 | – | ||
| milkvetch | ASTRA | Astragalus | 0–1 | – | ||
| spiderling | BOERH2 | Boerhavia | 0–1 | – | ||
| hoary bowlesia | BOIN3 | Bowlesia incana | 0–1 | – | ||
| exserted Indian paintbrush | CAEXE | Castilleja exserta ssp. exserta | 0–1 | – | ||
| yellow tackstem | CAPA7 | Calycoseris parryi | 0–1 | – | ||
| white tackstem | CAWR | Calycoseris wrightii | 0–1 | – | ||
| brittle spineflower | CHBR | Chorizanthe brevicornu | 0–1 | – | ||
| lipfern | CHEIL | Cheilanthes | 0–1 | – | ||
| hyssopleaf sandmat | CHHY3 | Chamaesyce hyssopifolia | 0–1 | – | ||
| New Mexico thistle | CINE | Cirsium neomexicanum | 0–1 | – | ||
| cryptantha | CRYPT | Cryptantha | 0–1 | – | ||
| bigseed alfalfa dodder | CUIN | Cuscuta indecora | 0–1 | – | ||
| American wild carrot | DAPU3 | Daucus pusillus | 0–1 | – | ||
| desert larkspur | DEPA | Delphinium parishii | 0–1 | – | ||
| western tansymustard | DEPI | Descurainia pinnata | 0–1 | – | ||
| tall mountain larkspur | DESC | Delphinium scaposum | 0–1 | – | ||
| bluedicks | DICA14 | Dichelostemma capitatum | 0–1 | – | ||
| flatcrown buckwheat | ERDE6 | Eriogonum deflexum | 0–1 | – | ||
| miniature woollystar | ERDI2 | Eriastrum diffusum | 0–1 | – | ||
| erigenia | ERIGE | Erigenia | 0–1 | – | ||
| buckwheat | ERIOG | Eriogonum | 0–1 | – | ||
| common woolly sunflower | ERLA6 | Eriophyllum lanatum | 0–1 | – | ||
| California poppy | ESCAM | Eschscholzia californica ssp. mexicana | 0–1 | – | ||
| desert poppy | ESGL | Eschscholzia glyptosperma | 0–1 | – | ||
| pygmy poppy | ESMI | Eschscholzia minutiflora | 0–1 | – | ||
| gilia | GILIA | Gilia | 0–1 | – | ||
| Gordon's bladderpod | LEGO | Lesquerella gordonii | 0–1 | – | ||
| shaggyfruit pepperweed | LELA | Lepidium lasiocarpum | 0–1 | – | ||
| Bigelow's linanthus | LIBI2 | Linanthus bigelovii | 0–1 | – | ||
| shrubby deervetch | LORI3 | Lotus rigidus | 0–1 | – | ||
| coastal bird's-foot trefoil | LOSA | Lotus salsuginosus | 0–1 | – | ||
| Coulter's lupine | LUSP2 | Lupinus sparsiflorus | 0–1 | – | ||
| tansyaster | MACHA | Machaeranthera | 0–1 | – | ||
| Parry's false prairie-clover | MAPA7 | Marina parryi | 0–1 | – | ||
| blazingstar | MENTZ | Mentzelia | 0–1 | – | ||
|
Shrub/Vine
|
||||||
| 5 | 25–75 | |||||
| 6 | 5–25 | |||||
| organpipe cactus | STTH3 | Stenocereus thurberi | 0–5 | – | ||
| beavertail pricklypear | OPBA2 | Opuntia basilaris | 0–2 | – | ||
| Leconte's barrel cactus | FECYL | Ferocactus cylindraceus var. lecontei | 0–2 | – | ||
| candy barrelcactus | FEWI | Ferocactus wislizeni | 0–2 | – | ||
| Engelmann's hedgehog cactus | ECEN | Echinocereus engelmannii | 0–1 | – | ||
| senita cactus | PASC14 | Pachycereus schottii | 0–1 | – | ||
| 7 | 125–175 | |||||
| triangle bur ragweed | AMDE4 | Ambrosia deltoidea | 75–125 | – | ||
| brittlebush | ENFA | Encelia farinosa | 25–50 | – | ||
| 8 | 50–75 | |||||
| Mexican bladdersage | SAME | Salazaria mexicana | 0–10 | – | ||
| Parish's goldeneye | VIPA14 | Viguiera parishii | 0–5 | – | ||
| white ratany | KRGR | Krameria grayi | 0–5 | – | ||
| rush milkweed | ASSU | Asclepias subulata | 0–5 | – | ||
| elephant tree | BUMI | Bursera microphylla | 0–5 | – | ||
| fairyduster | CAER | Calliandra eriophylla | 0–3 | – | ||
| starry bedstraw | GASTE2 | Galium stellatum ssp. eremicum | 0–3 | – | ||
| sangre de cristo | JACA2 | Jatropha cardiophylla | 0–3 | – | ||
| littleleaf ratany | KRER | Krameria erecta | 0–2 | – | ||
| creosote bush | LATR2 | Larrea tridentata | 0–2 | – | ||
| singlewhorl burrobrush | HYMO | Hymenoclea monogyra | 0–2 | – | ||
| Sonoran croton | CRSO | Croton sonorae | 0–2 | – | ||
| Nevada jointfir | EPNE | Ephedra nevadensis | 0–2 | – | ||
| Eastern Mojave buckwheat | ERFA2 | Eriogonum fasciculatum | 0–2 | – | ||
| bastardsage | ERWR | Eriogonum wrightii | 0–2 | – | ||
| sweetbush | BEJU | Bebbia juncea | 0–2 | – | ||
| Coulter's brickellbush | BRCO | Brickellia coulteri | 0–2 | – | ||
| Wright's beebrush | ALWR | Aloysia wrightii | 0–2 | – | ||
| burrobush | AMDU2 | Ambrosia dumosa | 0–2 | – | ||
| California copperleaf | ACCA3 | Acalypha californica | 0–2 | – | ||
| catclaw acacia | ACGR | Acacia greggii | 0–1 | – | ||
| arrow poision plant | SEBI9 | Sebastiania bilocularis | 0–1 | – | ||
| American threefold | TRCA8 | Trixis californica | 0–1 | – | ||
| water jacket | LYAN | Lycium andersonii | 0–1 | – | ||
| Fremont's desert-thorn | LYFR | Lycium fremontii | 0–1 | – | ||
| desert lavender | HYEM | Hyptis emoryi | 0–1 | – | ||
| 9 | 75–150 | |||||
| ocotillo | FOSP2 | Fouquieria splendens | 60–120 | – | ||
| desert ironwood | OLTE | Olneya tesota | 60–120 | – | ||
| yellow paloverde | PAMI5 | Parkinsonia microphylla | 60–120 | – | ||
| yellow paloverde | PAMI5 | Parkinsonia microphylla | 30–50 | – | ||
| ocotillo | FOSP2 | Fouquieria splendens | 20–40 | – | ||
| saguaro | CAGI10 | Carnegiea gigantea | 10–30 | – | ||
| desert ironwood | OLTE | Olneya tesota | 0–20 | – | ||
Interpretations
Animal community
Steep slopes and very cobbly to stony surfaces hinder livestock distribution. Stocker cattle are best adapted to use this site. The plant community provides limited amounts of useable forage in the winter-spring season. Natural water is unavailable on this site.
Water developments are very important to wildlife species on this site. Cover, diversity, and topography make areas of this site home to a variety of desert animals. Large mammals use the site seasonally unless permanent water supplies exist in the area. Desert tortoises den on cobble or stony slopes. Javalina bed on north aspects in paloverde thickets.
Other information
T&E: Leptonycteris cursoae yerbe buena
(Lesser long-nosed bat)
Supporting information
Type locality
| Location 1: Maricopa County, AZ | |
|---|---|
| Township/Range/Section | T3S R2E S33 |
| General legal description | Chandler FO - Gila River Indian Community, Sierra Estrella Mountains |
| Location 2: Pima County, AZ | |
| Township/Range/Section | T9S R4E S11 |
| General legal description | Sells FO - Tat Momolikat Mountains |
| Location 3: Maricopa County, AZ | |
| Township/Range/Section | T6S R1W S16 |
| General legal description | Buckeye FO - Maricopa Mountains, Ryff Ranch |
| Location 4: Pinal County, AZ | |
| Township/Range/Section | T7S R2E S5 |
| General legal description | Casa Grande FO - Ak Ranch, Antelope Peak |
| Location 5: Maricopa County, AZ | |
| Township/Range/Section | T4N R6W S32 |
| General legal description | Phoenix FO - Belmont Mountains |
| Location 6: Pima County, AZ | |
| Township/Range/Section | T17S R1E S26 |
| General legal description | Sells FO - Pisinemo District Kupk Hills |
Contributors
Dan Robinett
Dan Robinett, J. Norris
Larry D. Ellicott
Steve Barker
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, Byron Lambeth, Dan Robinett, Emilio Carrillo |
|---|---|
| Contact for lead author | NRCS Tucson Area Office |
| Date | 03/02/2005 |
| Approved by | S. Cassady |
| Approval date | |
| Composition (Indicators 10 and 12) based on | Annual Production |
Indicators
-
Number and extent of rills:
Follow faults and bedding planes in parent materials. -
Presence of water flow patterns:
Discontinuous, 10-15 feet in length. Will see shorter flow paths with high surface coarse fragments. -
Number and height of erosional pedestals or terracettes:
No accumulated or erosional pedestals. -
Bare ground from Ecological Site Description or other studies (rock, litter, lichen, moss, plant canopy are not bare ground):
1-15% (low values due to high rock and gravel cover) -
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):
Most litter size classes stay in place due to high rock and gravel cover. -
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 ratings of 1-3 in perennial plant interspaces, 4-5 under shrub canopies. -
Soil surface structure and SOM content (include type of structure and A-horizon color and thickness):
weak granular; color is 7.5-10YR6/3 dry, 7.5-1-YR5/4 moist, thickness to 2 inches. -
Effect of community phase composition (relative proportion of different functional groups) and spatial distribution on infiltration and runoff:
canopy 15-20%; 50% shrubs, 23% trees, 25% succulents and 1-2% perennial grasses. Cover is well dispersed throughout the site. -
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:
shrubs > subshrubs > trees > succulents > annual forbs and grasses > perennial forbs > perennial grasses.Sub-dominant:
Other:
Additional:
-
Amount of plant mortality and decadence (include which functional groups are expected to show mortality or decadence):
20-50% tree & shrub canopy mortality, 75-90% perennial grass mortality. -
Average percent litter cover (%) and depth ( in):
-
Expected annual annual-production (this is TOTAL above-ground annual-production, not just forage annual-production):
300 lbs/ac unfavorable precipitation, 500 lbs/ac normal precipitation, 800 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:
Sahara mustard, London Rocket -
Perennial plant reproductive capability:
Not impaired for shrubs, drought impaired for perennial grasses and forbs.
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