AUTHORSHIP AND CITATION:
Gucker, Corey L. 2005. Acacia greggii. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/ .
Revisions: The Senegalia greggii synonym and the supporting citations [9,24,72] were added on 27 August 2014.
Acacia greggii var. arizonica Isley 
= Acacia greggii var. greggii [30,69]
Senegalia greggii (A. Gray) Britt. & Rose [9,24,72]
NRCS PLANT CODE :
The currently accepted scientific name of catclaw acacia is Acacia greggii A. Gray (Fabaceae) [30,69]. Accepted varieties are:
Acacia greggii. var. greggii, Arizona acacia [30,69,73]
Acacia greggii. var. wrightii (Benth.) Isley, Wright acacia [30,69,73]
Throughout this review, catclaw acacia will refer to both varieties, A. g. var. greggii and A. g. var. wrightii. When citing literature that distinguishes variety, A. g. var. greggii will be referred to as Arizona acacia, and A. g. var. wrightii will be referred to as Wright acacia. When information is provided that pertains to the Acacia genus without indicating species, it will be noted as Acacia spp.
Hybrid: A. greggii hybridizes with A. berlandieri to
produce Acacia × emoryana Benth. [68,86].
FEDERAL LEGAL STATUS:
The 2 catclaw acacia varieties have partially overlapping ranges. Arizona acacia occurs throughout the entire range of catclaw acacia, while Wright acacia is restricted to New Mexico, western Texas, and Sonora, Tamaulipas, and Nuevo Leon, Mexico .
A distributional map of catclaw acacia can be accessed through the U.S. Geological Survey.
FRES30 Desert shrub
FRES32 Texas savanna
FRES33 Southwestern shrubsteppe
FRES34 Chaparral-mountain shrub
FRES38 Plains grasslands
FRES40 Desert grasslands
STATES/PROVINCES: (key to state/province abbreviations)
In drainages and minor waterways of the Lower Colorado Desert and parts of the Mohave Desert, catclaw acacia occurs in burrobush (Hymenoclea spp.)-dominated communities with Anderson wolfberry (Lycium andersonii), desertbroom (Baccharis sarothroides), cattle saltbush, and Mohave rabbitbrush [67,155].
Creosotebush (Larrea tridentata)-dominated communities are also typical in southern California. White bursage (Ambrosia dumosa), desert ironwood (Olneya tesota), blue paloverde (Parkinsonia florida), saguaro (Carnegiea gigantea), and catclaw acacia typify these communities [91,178]. Catclaw acacia is also typical of desert microphyll woodlands. Blue paloverde, smoketree, honey mesquite (Prosopis glandulosa), screwbean mesquite (P. pubescens), desert lavender (Hyptis emoryi), and creosotebush are typical of microphyll woodlands .
The Sonoran mixed woody and succulent scrub vegetation often includes catclaw acacia as well as desert agave (Agave deserti), brittle bush (Encelia farinosa), ocotillo (Fouquieria splendens), Schott's pygmycedar, Mohave yucca (Yucca schidigera), and prickly-pear (Opuntia spp.) .
Desert shrub communities of Nevada are dominated by smoketree, desert willow, Mohave desertrue (Thamnosma montana), brittle bush, triangle goldeneye (Viguiera deltoidea), pale wolfberry (Lycium pallidum), and catclaw acacia. Typical forb associates are strigose bird's-foot trefoil (Lotus strigosus var. tomentellus), foothill deervetch (L. humistratus), whitemargin sandmat Chamaesyce albomarginata, and desert globemallow (Sphaeralcea ambigua) .
Catclaw acacia occurs with desert wash vegetation. Common desert wash shrubs are desert willow, pale wolfberry, desertsenna (Senna armata), white burrobrush, bladdersage (Salazaria mexicana), and desert almond .
In Clark County, riparian areas are characterized by saltcedar (Tamarix ramosissma), velvet mesquite (P. velutina), desertbroom, and catclaw acacia .
Catclaw acacia is typical of several juniper (Juniperus spp.)-dominated communities. In Pinchot juniper (J. pinchotii) communities of western and north-central Texas, catclaw acacia, velvet mesquite, and sideoats grama (Bouteloua curtipendula) are common. In the Rolling Plains of western Texas, common associates are prickly-pears, soapweed yucca (Y. glauca var. glauca), lotebush (Ziziphus obtusifolia), catclaw mimosa (Mimosa biuncifera), Texas tussockgrass (Nassella leucotricha), and Arizona cottontop (Digitaria californica) [97,98]. A similar community in the Rolling Plains of north-central Texas includes fragrant sumac (R. aromatica), littleleaf sumac (R. microphylla), agarito (Mahonia trifoliolata), lotebush, threeawn grasses (Aristida spp.), and little bluestem (Schizachyrium scoparium) .
In the Big Bend region of Texas, catclaw acacia is interspersed in sotol (Dasylirion spp.)- juniper-lechuguilla (Agave lechuguilla) and shortgrass/juniper communities characterized by the presence of oneseed juniper (J. monosperma). Other vegetation can include ocotillo, oaks (Quercus spp.), sumacs (Rhus spp.), gramas (Bouteloua spp.), and threeawns .
Northwest of Uvalde, Texas, catclaw acacia occurs with Ashe juniper (J. ashei), Texas persimmon (Diospyros texana), mescalbean sophora (Sophora secundiflora), agarito, and coyotillo (Karwinskia humboldtiana) .
Catclaw acacia also occurs in several mesquite-dominated communities. In the southern Texas Plains, catclaw acacia is found in mesquite-bunchgrass-annual forb savannas, mesquite-bristlegrass (Setaria spp.)-forb woodland communities, and mesquite-granjeno (Celtis pallida)-dominated communities [31,149]. The mesquite-granjeno community, considered indicative of disturbance, commonly includes ocotillo, Brazilian bluewood (Condalia hookeri var. hookeri), lime pricklyash (Zanthoxylum fagara), and sweet acacia (Acacia farnesiana) . In the Chisos Mountains, the arroyo-mesquite-acacia association includes catclaw acacia, mesquite, mule's fat (Baccharis salicifolia), and desert willow .
Desert chaparral communities of the Rio Grande Plains and Texano-Mexican desert regions of Texas also include catclaw acacia [41,52]. Other species common to these desert chaparral communities are whitethorn acacia (A. constricta), fragrant mimosa (Mimosa borealis), catclaw mimosa, featherplume (Dalea formosa), Brazilian bluewood, knifeleaf condalia (C. spathulata), and ocotillo .
Tarbush (Flourensia cernua) is often associated with catclaw acacia. In the creosote-tarbush association in Big Bend, catclaw acacia occurs with mariola (Parthenium incanum), white ratany (Krameria grayi), Big Bend barometerbush (Leucophyllum minus), longleaf jointfir (Ephedra trifurca), crown of thorns (Koeberlinia spinosa), yuccas, and javelin bush (C. ericoides). In the tobosa (Pleuraphis mutica)-tarbush habitat of Big Bend, grass cover is sparse. Acacias, velvetpod mimosa (M. dysocarpa), barometerbushes (Leucophyllum spp.), and snakeweeds (Gutierrezia spp.) dominate the community .
Catclaw acacia is also described with shortgrass-yucca communities. The shortgrasses are typically sideoats grama, muhly grasses (Muhlenbergia spp.), lovegrasses (Eragrostis spp.), and bluestems (Andropogon spp.) .
Catclaw acacia is typical in Chihuahuan desert scrub and woodlands. Creosote, tarbush, viscid acacia (Acacia neovernicosa), barometerbushes, mesquite, desert honeysuckles (Anisacanthus spp.), and catclaw acacia characterize the creosote scrub vegetation. Apacheplume (Fallugia paradoxa), splitleaf brickellbush (Brickellia laciniata), granjeno, guajillo (Acacia berlandieri), little walnut (Juglans microcarpa), and American pistachio (Pistacia mexicana) characterize sandy arroyo scrub vegetation .
In both mesquite scrub and creosotebush desert communities catclaw acacia is characteristic .
Catclaw acacia is associated with desert shrub, desert grassland, and arroyo riparian vegetation [19,28,172]. In the Guadalupe Mountains, catclaw acacia occurs with Pinchot juniper, lechuguilla, smooth sotol (Dasylirion leiophyllum), mariola, featherplume, threeawns, sideoats grama, and purple muhly (M. rigida) . In the southern Great Plains of Lea County, black grama (Bouteloua eriopoda), tobosa, mesquite, whitethorn acacia, snakeweeds, and catclaw acacia are common .
In the Chihuahuan and Sonoran deserts, catclaw acacia populates the edges of secondary and lesser riparian systems .
In the Utah juniper (Juniperus osteosperma)/tobosa and redberry juniper (J. coahuilensis/shrub live oak (Q. turbinella) vegetation types of the Mogollon Rim, mesquite, redberry juniper, Utah juniper, and catclaw acacia are common. Singleleaf pinyon (Pinus monophylla), catclaw mimosa, broom snakeweed (G. sarothrae), and sacahuista (Nolina microcarpa) characterize the Utah juniper/tobosa community. Yellow paloverde (Parkinsonia microphylla), red barberry, and Fremont mahonia (Mahonia fremontii) occur in the redberry juniper/shrub live oak community .
Catclaw acacia is recognized in many grassland and shrub/grassland community types [25,58]. Grass-dominated communities include grassland-mesquite and grassland-desert shrub vegetation types. Typical grass species in both the grass and shrub dominated vegetation include gramas, threeawns, bullgrass (Muhly emersleyi), needlegrasses (Achnatherum spp.), dropseeds, and sacatons (both are Sporobolus spp.). Mesquite-grassland, desert shrub, desert shrub grassland, and desert shrub-half shrub vegetation types represent the shrub dominated communities. Mesquite, ocotillo, and acacias can be present in all the aforementioned shrub-dominated communities. The desert shrub-half shrub community has an understory of snakeweeds [25,50].
Desert wash and riparian vegetation described for south-central Arizona commonly includes catclaw acacia, paloverde, and mesquite [61,168,174]. Desert riparian communities are also habitat for whitethorn acacia, bursage (Ambrosia spp.), Berlandier's wolfberry, desert ironwood, Drummond's clematis (Clematis drummondii), and fingerleaf gourd (Cucurbita digitata) .
In central Arizona, catclaw acacia is associated with juniper- and shrub live oak-dominated vegetation. In the Coconino National Forest, catclaw acacia is found with Utah juniper, shrub liveoak, manzanitas (Arctostaphylos spp.), bitterbrushes (Purshia spp.), desert ceanothus (Ceanothus greggii), and mountain-mahogany (Cercocarpus spp.) . Catclaw acacia is also present in shrub live oak-birchleaf mountain mahogany (C. betuloides), shrub live oak-mixed shrub, and pointleaf manzanita (A. pungens) communities .
Catclaw acacia in southeastern Arizona associates with desert scrub vegetation types. In the Santa Catalina Mountains, low densities of catclaw acacia are found in creosotebush desert scrub communities. Bursage desert scrub vegetation includes fishhook pincushion (Mammillaria grahamii var. grahamii), triangle bursage (Ambrosia deltoidea), and catclaw acacia. The arroyo margin woodland vegetation is often characterized by the presence of singlewhorl burrobush (Hymenoclea monogyra), honey mesquite, and catclaw acacia. Increased densities of catclaw acacia occur in disturbed desert scrub communities with burroweed (Isocoma tenuisecta) and brittle brush and in spinose suffrutescent desert scrub communities with slender janusia (Janusia gracilis), yellow paloverde, and ocotillo .
Catclaw acacia is a native, long-lived, deciduous, spreading shrub or small tree [33,107,164]. Depending on the harshness of site conditions, catclaw acacia typically ranges from 3.3 to 29.5 feet (1-9 m) tall [107,164]. On the Lower Rio Grande River, catclaw acacia trees measured 35 feet (10.7 m) . The main trunk can be 12 inches (30.5 cm) in diameter; the bark is commonly 3.2 mm thick, developing cracks and becoming scale-like with age . Catclaw acacia is heavily armed with stout, curved spines (3-4 mm long) distributed along branches at the internodes [30,74,93,107,170].
Alternate leaves are bipinnate with 4 to 7 leaflet pairs. Leaves measure 0.8 to 2 inches (2-5 cm) long. Leaflets are between 2 and 12 mm long and are normally hairy [30,107,170]. Catclaw acacia has extrafloral nectaries on the primary rachis that are thought to promote mutualistic interactions between catclaw acacia and insects, commonly ants. The ants provide protection from other insect herbivores, while the extrafloral nectaries provide the ant with food and water . Catclaw acacia's legume fruits are straight to twisted, constricted between the seeds, and measure 2 to 4.7 inches (5-12 cm) long by 0.4 to 0.8 inches (1-2 cm) wide [30,56,74,93,107]. Seeds are round and typically 5-7 mm in size . Although catclaw acacia is a legume, in controlled experiments nodulation has not occurred [35,181].
Catclaw acacia is highly adapted to harsh desert conditions. A deep root system, high water use efficiency, high photosynthetic capacity, and use of the C3 photosynthetic pathway allow catclaw acacia to thrive in harsh desert climates [13,33,44,67,84]. Zimmerman  observed catclaw acacia roots greater than 18 feet (5.5 m) deep in southeastern Arizona. On a wash site in the Gold Valley of the Mohave Desert, 55% of the total catclaw acacia dry weight was root .
Catclaw acacia is long lived. Catclaw acacia shrubs were aged from repeat photographs
of Grand Canyon sites. Photographs indicate that 85% of the plants on the sites were at
least 104 years old. Other pictures showed that 5 of 6 plants were at least 120 years old.
Researchers estimated 15% mortality and 27% recruitment in 100 years from the photographs
RAUNKIAER  LIFE FORM:
Catclaw acacia reproduces sexually through seed production, and when top-killed, catclaw acacia regenerates asexually through root crown sprouts [10,36,55,59,94].
Breeding system: No information is available on this topic.
Pollination: Catclaw acacia is considered an important honey plant [74,85,125], and likely bees are the chief flower pollinators.
Seed production: Seed predation is common for catclaw acacia (see IMPORTANCE TO LIVESTOCK AND WILDLIFE section).
Seed dispersal: Dispersal of catclaw acacia seed can result from animal movements and abiotic disturbances. In the Chihuahuan Desert of Arizona and New Mexico, researchers found that plant material used by cactus wrens to construct nests often include seeds. One of 12 cactus wren nests contained catclaw acacia seed. Collections are commonly made greater than 65.6 feet (20 m) from the nest site making nest construction a seed dispersal mechanism . Likely grazing animals disperse catclaw acacia seed [6,60]. No studies addressed seed viability once passed through the digestive tract.
Following heavy rainfall (76% of annual average) in San Diego County, California, 612 catclaw seedlings per hectare occurred on a site void of mature catclaw acacia. However, catclaw acacia occurred in washes upstream from the site. Most likely the storm relocated seeds from the wash to produce the catclaw acacia seedling population .
Seed banking: Seed bank development by catclaw acacia is not well understood. While some suggest a persistent seed bank , others recovered no catclaw acacia seed from 240 soil samples taken from herbicide treated and control sites in the Chihuahuan Desert of Texas. Researchers suggested heavy seed predation, reliance on a short-lived seed bank, and/or dependence on asexual reproduction to explain the lack of catclaw acacia seed in soils samples .
Germination: Temperature and moisture requirements must be met for catclaw acacia seed to germinate. Bowers  suggests that August and September seed germination is triggered by 1.2 inches (30 mm) or more of rainfall. Jordan and Haferkamp  suggest temperatures above 45 °F (7.2 °C) are required to germinate catclaw acacia seed. In California's Joshua Tree National Monument, catclaw acacia germinated only in August and September . However, factors other than temperature and moisture may affect germination. Even when able to control growing conditions, horticulturists were unable to germinate seed collected from plants in 1927, while seed collected in 1929 germinated .
Seedling establishment/growth: Site conditions and early disturbances affect catclaw acacia seedling development. Perkins and Owens  found seedling growth was greatest when plants were exposed to full sunlight. When defoliated early in development, catclaw acacia seedlings had significantly (p<0.01) less total biomass than nondefoliated seedlings.
Many Sonoran Desert species including catclaw acacia are described in a seedling identification key. Descriptions are provided for catclaw acacia seedlings from 1 to 45 days after emergence. A strong nitrogen odor is given off when seedlings are uprooted. This same trait is described for other Acacia spp. but not all Fabaceae species .
Catclaw acacia readily reproduces vegetatively following the removal of aboveground biomass
Catclaw acacia occupies dry gravelly mesas, canyons, arroyo banks, rocky hillsides, desert flats, washes, floodplains, and riparian areas in arid to semiarid southwestern regions [16,89,101,164,175].
|Arizona||below 4,500 feet (1,372 m) [16,74]|
|California||below 6,000 feet (1,829 m) |
|New Mexico||3,500 to 5,000 feet (1,067-1,524 m) |
|Texas||1,000 to 6,000 feet (305-1,829 m) [27,125,164,169]|
|Utah||2,490 to 2,850 feet (760-870 m) [34,170]|
Soils: The desert soils typical of catclaw acacia habitat are low in organic matter, can be slightly acidic to slightly alkaline, are often shallow (< 12 inches (30.5 cm) deep), and commonly contain calcium carbonate in the upper 6.6 feet (2 m) of soil. The caliche layer can be thick and impenetrable [90,92].
Climate: The climate regimes described for catclaw acacia habitats range from mild to severe. In southwestern semiarid deserts, winters are often mild and summers are warm to hot. Annual average precipitation predominantly ranges from 8 to 20 inches (203-508 mm) . Precipitation levels can be much lower in the Sonoran and Chihuahuan deserts where annual precipitation levels range from 2 to 12 inches (51-305 mm) and 3 to 16 inches (76-406 mm), respectively .
In the lower Colorado Desert of southern California, precipitation is between 2.5 and
4 inches (63.5-102 mm) annually, relative humidity is extremely low, and high
summer temperatures can reach 120 °F (49 °C) . The chaparral-desert ecotone of southern
California on average receives 12.6 inches (321 mm) of precipitation annually, 69-78% of which
falls from October through April . A bimodal rain pattern is typical for Arizona deserts.
The 14.5 to 17 inches (368-434 mm) of annual rain falls in the winter and early spring and again
in mid- to late summer; late spring and early summer are arid [1,13]. April
through June in Tucson received little over 0.5 inch (12.7 mm) for a recorded 27 year
average . In central Arizona, winter temperatures are between 32
°F and 68 °F (0 °C-21 °C) and summer temperatures range from 70 °F to 109 °F (21 °C-43 °C).
Southern Nevada weather is also characterized by bimodal precipitation with widespread
winter rain and intense summer monsoons . Maximum high and low temperatures in Clark County,
Nevada, are wide ranging. The winter minimum can be 32 °F (0 °C) and summer maximums are often
as high as 102 °F (39 °C) . Temperatures are more extreme for the Desert Plains of
Brewster County, Texas, where lows and highs range from 10 °F (-12 °C) to 120 °F
(49 °C). This area receives less than 10 inches (254 mm) of precipitation/year
The concept of succession, in which community composition changes over time as a site is modified by past and present species, was developed in mesic eastern forests and does not apply well to southwestern desert ecosystem dynamics. In eastern forest ecosystems, pioneer species are typically not present in climax communities. In southwestern deserts, species that make up the predisturbed vegetation are the same species that make up the recovering vegetation . While true Clementsian succession does not occur in semiarid and arid ecosystems, it is possible to see shifts in species dominance in relation to disturbance . The continued use of many traditional succession terms to explain desert community change or development is likely due to the lack of more appropriate terms.
In the case of catclaw acacia, the terms "postclimax", "disclimax", and "subclimax" have been used to describe this species' response to various disturbances. In the southern desert plains, mesquite-acacia vegetation that increased in abundance and extent with disturbance is labeled "postclimax" . Others classified catclaw acacia as an "invader" species when it appeared late in the stages of community degradation in the Guadalupe Mountains of New Mexico . In the south Texas Plains, catclaw acacia is one of several species considered dominant in the mesquite-granjeno disturbance community type . Dick-Peddie and Alberico  described vegetation dominated by beebrushes (Aloysia spp.), lechuguilla, tulip prickly pear (Opuntia phaeacantha), blue grama (Bouteloua gracilis), sideoats grama, whitethorn acacia, and catclaw acacia as "disclimax" vegetation maintained through grazing and fire reduction. Whitfield and Anderson  considered sacaton vegetation, typically including catclaw acacia, an edaphic "subclimax" community persisting on heavy clay or alkali soils of washes and flood plains.
When studying different-aged debris flows in the Grand Canyon of Arizona, Bowers and others  found catclaw acacia in almost all but the youngest and oldest communities. The percent coverage and densities of catclaw acacia on different aged debris flows are presented below.
|Time (in years) since last flow||5||28||28||32||43||47||55||240||285||485||3100|
Fire regimes: Across the range of habitats occupied by catclaw acacia, historical fire regimes vary widely. Semiarid grassland communities likely burned often while extremely arid thorn scrub communities rarely burned. European settlement and changes in land use have substantially affected the likelihood of fire in these communities.
Grassland communities: Early settlers and explorers described grasslands across large areas of the Southwest, while descriptions of woody vegetation suggested its restriction to waterways and rocky hillsides . Decreased fire frequencies in grasslands are often considered the reason for dense shrub communities in areas once dominated by grasses [2,29]. Frequent fires limited woody vegetation establishment, maintaining grasslands . Likely the fire frequency in desert grasslands was such that shrubs were killed in the seedling stage or prior to reaching reproductive maturity .
High numbers of cattle grazing these grasslands directly and indirectly promoted the rapid conversion of grassland-dominated areas to shrub-dominated areas . Grazing animals likely dispersed shrub seed. The selective removal of grasses decreased the "competition" between grasses and establishing shrubs and decreased available fuels and eventually fire frequencies [6,60]. McPherson  predicted future changes in the desert grassland fire regime. Decreases in cattle grazing and increases in nonnative grasses may favor more frequent fires than did the last century, yet a return to historic fire frequencies is highly unlikely due to fragmented fuels and continued fire suppression efforts. However McPherson recognizes that changes in climate, political agendas, and land use will continue to affect desert grassland fire regimes .
Cactus and desert scrub communities: In the Mohave, Sonoran, and Chihuahuan deserts, the dominant vegetation is widely spaced, open-branched, and not prone to burning. Biomass production by native perennial grasses and forbs is low and coverage is sparse, resulting in noncontinuous fuels [62,162]. Historically in the Mohave Desert, the most arid of the North American deserts, fires were extremely rare. Fires were also rare in the Sonoran and Chihuahuan Deserts. The low-growing stature and dense shrub canopies of the Chihuahuan Desert make this desert slightly more fire prone than the taller and more widely spaced vegetation of the Sonoran Desert. Portions of the Sonoran and Chihuahuan deserts that bordered desert grassland systems burned more frequently . The lack of fire-adapted vegetation in these deserts is further evidence of fire rarity . Paloverde, saguaro, and other small cacti (pincushions (Scabiosa spp.) and prickly-pears) do not sprout following fire and are typically killed by even low-severity fires. It may take a century or more for saguaro and paloverde to develop from seed to large adult size [36,94].
As in grassland-dominated desert communities, European settlement and land use have inadvertently altered fire regimes in desert scrub and thorn scrub communities. Fires in these communities are more frequent than those that occurred historically [1,36,162]. The introduction and subsequent expansion of several nonnative species including red brome (Bromus madritensis spp. rubens), cheatgrass (B. tectorum), mediterranean grasses (Schismus spp.), buffelgrass (Pennisetum ciliare), and potentially ripgut brome (B. diandrus) increased fire risk in many desert scrub communities [1,36,122,162]. The displacement of native ephemeral species by these successful nonnative species creates easily ignited communities and supports large fires [94,122]. Increased fire frequencies in these fire-intolerant communities will likely alter their composition by removing fire sensitive species and increasing fire tolerant species [36,162]. Alford and Brock  studied the postburn vegetation response in fire sensitive Sonoran desert communities and found several native species (saguaro, foothill paloverde, white ratany, creosote bush, wolfberry) decreased while purple threeawn, senna, and red brome increased .
For further information regarding fire regimes and fire ecology of communities and ecosystems where catclaw acacia is found, see the FEIS species reviews for the plant community or ecosystem dominants listed below:
|Community or Ecosystem||Dominant Species||Fire Return Interval Range (years)|
|California chaparral||Adenostoma and/or Arctostaphylos spp.||< 35 to < 100 |
|bluestem prairie||Andropogon gerardii var. gerardii-Schizachyrium scoparium||< 10 [77,118]|
|bluestem-Sacahuista prairie||Andropogon littoralis-Spartina spartinae||< 10|
|desert grasslands||Bouteloua eriopoda and/or Pleuraphis mutica||5-100 |
|plains grasslands||Bouteloua spp.||< 35 [118,177]|
|blue grama-needle-and-thread grass-western wheatgrass||Bouteloua gracilis-Hesperostipa comata-Pascopyrum smithii||< 35 [118,134,177]|
|blue grama-tobosa prairie||Bouteloua gracilis-Pleuraphis mutica||< 35 to < 100|
|California montane chaparral||Ceanothus and/or Arctostaphylos spp.||50-100|
|paloverde-cactus shrub||Cercidium microphyllum/Opuntia spp.||< 35 to < 100 |
|curlleaf mountain-mahogany*||Cercocarpus ledifolius||13-1,000 [7,138]|
|mountain-mahogany-Gambel oak scrub||Cercocarpus ledifolius-Quercus gambelii||< 35 to < 100|
|blackbrush||Coleogyne ramosissima||< 35 to < 100|
|juniper-oak savanna||Juniperus ashei-Quercus virginiana||< 35|
|Ashe juniper||Juniperus ashei||< 35|
|creosotebush||Larrea tridentata||< 35 to < 100|
|Ceniza shrub||Larrea tridentata-Leucophyllum frutescens-Prosopis glandulosa||< 35|
|pinyon-juniper||Pinus-Juniperus spp.||< 35 |
|mesquite||Prosopis glandulosa||< 35 to < 100 [96,118]|
|mesquite-buffalo grass||Prosopis glandulosa-Buchloe dactyloides||< 35|
|Texas savanna||Prosopis glandulosa var. glandulosa||< 10|
|oak-juniper woodland (Southwest)||Quercus-Juniperus spp.||< 35 to < 200 |
|oak savanna||Quercus macrocarpa/Andropogon gerardii-Schizachyrium scoparium||2-14 [118,166]|
|little bluestem-grama prairie||Schizachyrium scoparium-Bouteloua spp.||< 35 |
Fire alone: The following studies illustrate the more typical postfire response for catclaw acacia. Following a fire in the Santa Rita Mountains of Arizona, 90% of catclaw acacia plants in wash areas were sprouting and 100% in the upland sites were sprouting. The timing of this fire was not clear . Following an early May fire in a south-central Arizona giant saguaro community, the density of catclaw acacia on burned and unburned sites was compared. Catclaw acacia density (plant/0.5 ha) was 44 on unburned sites and 42 on burned sites . In south-central Arizona following a June fire, the percentage of postfire catclaw acacia sprouts ranged from 75% to 100% .
In a study of the recovery of Sonoran Desert vegetation following fire, burned areas were sampled and compared to nearby unburned areas. Given below are the mean heights, canopy covers, and densities for catclaw acacia on 21-year-old burns, repeatedly burned sites (4 fires in 30 years), and unburned sites. Both canopy coverage and density increased with repeated burning :
|Fire history||Height (m)||Canopy cover (%)||Density (number/ha)|
|Repeated fires (4 in 30 yrs.)||2.1||1.9||0.2||0.9||28||57|
After a July fire in Los Angeles County, California, the postfire recovery of chaparral-desert ecotone vegetation was assessed. Catclaw acacia averaged 166 sprouts per plant following the fire, and survival by postfire sprouting was high. Density on the ridge sites was lower than on canyon sites. The postfire response for catclaw acacia is provided below :
|Site||Estimated prefire density (plants/ha)||Postfire density (plants/ha)|
|Site||2 months postfire (sprouts/ha)||4 months postfire (sprouts/ha)||7 months postfire (sprouts/ha)||10 months postfire (sprouts/ha)|
Fire in conjunction with other disturbances: The following studies involve use of fire and other disturbances as a means of reducing woody vegetation. The prescribed fire timing for these studies often differs from presettlement fire regimes for the areas. In the Rolling Plains and Edwards Plateau regions of Texas, sites chained then burned reduced catclaw acacia cover by 40%. Chaining occurred 4 to 5 years prior to a late winter prescription fire, and coverage change measurements occurred 2 years postfire .
In the San Simon Valley of southeastern Arizona, researchers assessed the effects of grazing and fire in a shrub-invaded grassland. The average ground cover (number of counts/500 census locations) for catclaw acacia on all plots was 3.7% prior to any treatments. Fires occurred on the 20th or 21st of June 1993. Catclaw acacia coverage decreased on burned and grazed plots. Coverage initially decreased on unburned grazed plots but decreases were short lived. The resulting changes in ground cover for catclaw acacia are presented below (note: Burned, B; Unburned, UB; Grazed, G; Ungrazed, UG) :
|Postburn sampling year||1993||1995|
|Ground cover (%)||1.8||6.2||0.4||0.6||3.0||7.8||13.6||8.4|
Repeated fires: Another method used to control woody vegetation is repetitive burning. Catclaw acacia seems tolerant of repeated fires that allow for at least a year between fires; however, fires that burn within the same year resulted in decreased catclaw acacia cover and density. In the Rio Grande Plains of Texas, researchers annually and biennially burned mesquite-acacia savannahs during the dormant (January-February) and growing (July-August) seasons. Growing season fires burned when air temperatures were between 95 °F and 104 °F (35 °C-40 °C), wind speeds were 2.2 to 5.4 m/s, and relative humidity was 20% to 50%. Dormant season fires burned when air temperatures were 44.6 °F to 64.4 °F (7 °C-18 °C), winds were 1.3 to 4.5 m/s, and relative humidity was 65% to 80%. For the biennial burning schedule, a total of 2 fires burned during the study. The dormant season annual fires occurred for 4 consecutive years while the growing season annual fires burned for 3 consecutive years. Regardless of burn prescription, catclaw acacia coverage was greater on burned sites. The changes in catclaw acacia cover are provided below :
|Burn season||Dormant (January-February)||Growing (July-August)|
|Mean catclaw acacia cover (%)||0.2||1.5||2.6||0.7||2.3||2.0|
In the western South Texas Plains, some sites were burned for 2 consecutive winter seasons (winter burn). Other sites were burned in the winter and burned again the following summer (winter-summer burn), while other sites were unburned. Catclaw acacia cover and density increased following the winter burn and decreased following the winter-summer burn treatment. The longevity of these changes is unknown. The changes in catclaw acacia given different patterns of burning are given below :
|Fire treatment||Unburned||Winter burn||Winter-summer burn|
|Mean percent cover||0.3||1.0||0.1|
|Mean density (stems/ha)||36||121||25|
Using fire to decrease shrub cover, increase herbaceous cover, and/or alter stream flows requires repetitive burning and integrated management. Hibbert and others  suggest prescription burns in chaparral-dominated brush communities alone do not often significantly reduce shrub cover. Many shrubs in this community, including catclaw acacia, sprout following fire, and likely only fire-sensitive species are killed. A combination of fire and other control methods is necessary to substantially reduce the shrub component from chaparral communities . Humphrey  suggests that fires every 5-10 years in desert grasslands could control woody vegetation encroachment .
The effectiveness of fire as a tool to combat increases in nonnative species is unknown for many desert areas. In saguaro-paloverde dominated Sonoran Desert communities, postfire rehabilitation measures are necessary following any prescription fires designed to control nonnative species, as these communities are not fire adapted . In southeastern Arizona, hawk's eye (Euryops multifidus) displaced native grasses and shrubs (including catclaw acacia). The response of hawk's eye monocultures to fire or other natural disturbance processes is unknown .
When considering the postfire response of vegetation, postfire utilization is important. In Anza-Borrego Desert State Park of California, researchers assessed the utilization of catclaw acacia by herbivores following a July fire. The number of catclaw acacia sprouts per hectare browsed by wildlife varied by season. For the number of sprouts produced postfire, see the Fire alone section above. The utilization of new sprouts was greatest in the fall and winter months. Sprout browsing results are provided below :
Livestock: Catclaw acacia is typically grazed in the spring or when new growth is available, but animal densities and availability of other forage also affect livestock use of catclaw acacia. Humphrey  considered catclaw acacia marginal cattle forage. Utilization of catclaw acacia is typically restricted to spring when young twigs and leaves are available. Humphrey  considered mature pods "worthless as feed." In areas of the Kofa National Wildlife Refuge in Yuma County, Arizona, browsing of Acacia spp. occurred in areas where cattle numbers were high . In Coahuila, Mexico the diets of goats were monitored for 3 years. Utilization was highest by goats in the summer and fall. The percentage of their diets constituting catclaw acacia is shown below :
|Percent diet composition||0.3%||0%||4.5%||0%||8.5%|
In another northeastern Mexico study, goat grazing of catclaw acacia followed no seasonal pattern .
Deer: The utilization of catclaw acacia by both mule and white-tailed deer varies with year, season, and climate conditions. In a 4-year-long study of mule deer and white-tailed deer diets in southeastern Arizona, researchers found that only mule deer fed on catclaw acacia. Catclaw acacia was approximately 4% of mule deer diets from February through April and about 18% in May, June, and July. The disproportionate usage between deer species was likely because white-tailed deer inhabited higher elevations where catclaw acacia was rare . In the Tonto National Forest of south-central Arizona, both white-tailed deer and mule deer fed on catclaw acacia. Stomach content analyses revealed catclaw acacia usage was greatest (14% average volume) for 11 mule deer taken in mid-summer. For white-tailed deer, catclaw acacia usage was greatest (16% average volume) for 5 deer taken in late December. Utilization of catclaw acacia in all other seasons was low (0%-2%) by both white-tailed and mule deer . In the Belmont Mountains of Arizona, mule deer utilized catclaw acacia most in the winter months, but high utilization rates occurred in only 1 of 3 sampling years . In the Sonoran Desert south of Tucson, catclaw acacia made up 17.9%, 1.9%, 11.2%, and 3.9% of mule deer diets in the spring, summer, fall, and winter, respectively . However, in the Coconino National Forest of Arizona, catclaw acacia made up just 0.05%, 0.2%, and 0.04% of trained mule deer diets in the winter, spring, and summer, respectively .
Mule deer browsing increased with drought conditions in south-central Arizona. Mule deer diets when precipitation levels were 6 inches (154 mm) below average contained 6 times more catclaw acacia than during a normal precipitation year. The percent volume of catclaw acacia eaten from March through July during a normal precipitation year was 2.1 ±1.1 and during the drought was 12.3±4.4 . Many factors could account for the variable use of catclaw acacia by deer. Past disturbances, availability of other vegetation, and/or herbivore population density fluctuations may affect utilization rates.
Other ungulates: Catclaw acacia is an important food for both collared peccaries and feral asses. In southern Arizona, Eddy  observed collared peccaries feeding, and based on time-spent-feeding data, he established that catclaw acacia beans constituted 3%-5% of the collared peccary diet from July through September. Researchers described catclaw acacia beans as "relished" by collared peccaries . Feral asses in the Mohave Desert consistently utilize catclaw acacia. The highest levels of use occur from October through January when catclaw acacia makes up about 10% of the feral ass diet .
Carnivores: The following studies indicate that carnivores may utilize catclaw acacia. Murie  found a single coyote scat comprised primarily of catclaw acacia, which was a rare component of the area's vegetation. In central Arizona, mountain lions buried 2 of 9 pronghorn kills under catclaw acacia and shrub live oak brush thickets .
Small mammals: Rodents and rabbits commonly feed on catclaw acacia. In southeastern Arizona and southwestern New Mexico, researchers recovered catclaw acacia flowers, leaves, and empty seed pods from western white-throated woodrat dens . Gullion  reports that a conservation officer in Nevada observed beaver eating catclaw acacia when Lake Mohave flooded more preferred vegetation. Mature catclaw acacia is not preferred by desert cottontails and jackrabbits, but nonetheless is important. Rabbits browsed newly planted catclaw acacia in Riverside county, California . Turkowski  found Acacia spp. (catclaw and whitethorn) comprised a majority of desert cottontail diets in March and April during an exceptionally dry season (0 precipitation from January to April). Vohries and Taylor  similarly report the utilization of large stem bark, small diameter branches (.06-.33 inches), and leaf buds by both antelope jackrabbits and black-tailed jackrabbits during dry seasons.
Game birds: Catclaw acacia provides nesting habitat, roosting sites, and food for several game birds. In southern Arizona, 11 of 87 Gambel's quail roosting sites were in Acacia spp., while 1 of 3 located nests were under Acacia spp. . Scaled quail also nest under Acacia spp. . Catclaw acacia is an important year-round food source for both Gambel's and scaled quail [48,167]. In Brewster County, Texas, a region considered the geographic center of the scaled quail's range, catclaw acacia fruits were in more than 10% of 71 crops analyzed throughout the year, and catclaw acacia was the 8th most frequently consumed food by scaled quail . White-winged doves also feed on catclaw acacia seeds .
Other birds: The use of catclaw acacia for nesting and foraging by southwestern birds is extensive. In southern Nevada, catclaw acacia received 19% relative use as nesting sites by breeding desert birds . In southeastern New Mexico, cactus wren and loggerhead shrike breeding pairs chose catclaw acacia for nesting sites, in an area where catclaw acacia was uncommon . Two of 12 cactus wren nests studied in the Chihuahuan Desert of Arizona and New Mexico were found in catclaw acacia shrubs. Catclaw acacia was used as nest material in another cactus wren nest . Black-throated sparrows used catclaw acacia greater than 6.6 feet (2 m) tall for nesting . Lesser nighthawks nested under Acacia spp. . In Arizona's Organ Pipe National Monument, verdins used Acacia spp. (whitethorn and catclaw) most when foraging; phainopeplas used Acacia spp. second to mesquite when foraging. Black-tailed gnatcatchers, ash-throated flycatchers, and Gila woodpeckers also used Acacia spp. for foraging, but usage was much less .
In other studies, many birds preferred catclaw acacia habitats. Black-chinned hummingbirds, ladder-backed woodpeckers, ash-throated flycatchers, verdins, cactus wrens, mockingbirds, black-tailed gnatcatchers, brown-headed cowbirds, pyrrhuloxias, and house finches utilize desert shrub habitats where catclaw acacia is common in the Chisos Mountains of Texas . Habitat used by the endangered ferruginous pygmy owl includes communities where catclaw acacia is common. Sonoran desert scrub vegetation dominated by mesquite, palo verde, desert hackberry, and catclaw acacia may connect pygmy owl habitats and populations .
Palatability/nutritional value: Many have studied the chemical composition of catclaw acacia. Compositional differences may reflect climate, region, soil, and/or collection differences.
In the Edward Plateau region of Texas, researchers assessed the nutritional value of leaves collected from April through July and twigs collected in July. As a general trend, the highest values came from plant material collected earliest, while the lowest values corresponded to the later collections. The nutritional contents are provided below :
|Water||Ash||Protein||Phosphorus||Digestible organic matter|
Catclaw acacia and other leguminous shrubs in the area are considered an important summer protein source for mule deer . The chemical composition of catclaw acacia fruits collected in late June from Arizona chaparral and desert habitats is provided below. The in vitro digestibility was 32% for mule deer and 29% for white-tailed deer .
|Vegetation analyzed||Crude protein||Acid-detergent fiber||Calcium||Phosphorus|
For catclaw acacia foliage collected in the fall from the Tamaulipas shrubland in Nuevo Leon, Mexico, the chemical composition was :
|Organic matter||Crude protein||Ash||Cell wall||Acid detergent fiber||Cellulose||Hemicellulose||Lignin|
Several other chemical composition studies involved the collection and analysis of plant material throughout the year. The range of catclaw acacia leaf nutrient contents as seasons change is provided below for northeast Mexico :
|Nutrient||Calcium (g/kg)||Magnesium (g/kg)||Potassium (g/kg)||Zinc (mg/kg)||Copper (mg/kg)||Manganese (mg/kg)||Phosphorus (g/kg)||Iron (mg/kg)|
|Range by season||10 spring- 13 summer||5 spring- 7 summer||9 summer-12 spring||17 winter-20 spring||5 winter- 6 summer||17 spring- 25 winter||0.6 summer- 2.6 spring||192 winter-198 summer|
In several regions of Arizona (Picacho Mountain lowlands, King Valley, and the Harquahala Mountains) researchers analyzed the nutritional composition of catclaw acacia. The results are given below [76,130,140]:
|Month collected||Protein (%)||Acid detergent fiber (%)||Neutral detergent fiber (%)||Lignin (%)||Ether extract (lipid) (%)||Ash (%)||Cellulose (%)||Cell soluble (%)||Hemicellulose (%)|
Catclaw acacia provides shelter, protection, and shade to a diversity of desert
mammals and birds. Trees or large shrubs (≥6.6 feet (2 m)) provide thermal
cover for bighorn sheep. Catclaw acacia normally reaches this height or greater,
allowing bighorn sheep to avoid direct sunlight and moderate high daytime temperatures
. Catclaw acacias are important cover for collared peccaries and shade for cattle as well
. The western white-throated woodrat uses catclaw acacia for den protection .
Similarly in the Santa Rita Range of Arizona, 66% of catclaw acacia shrubs inspected had
Merriam's kangaroo rat burrows beneath them . Catclaw acacia is also one of many desert
shrubs thought to provide protection to rabbits and rodents from coyote predation on the San
Carlos Reservation in Arizona . In the Mohave Desert, catclaw acacia provides patches
of cover for Gambel's quail as they move across inhospitable areas .
VALUE FOR REHABILITATION OF DISTURBED SITES:
Catclaw acacia is valuable in reclaiming asbestos, mining, and other disturbed sites. The use of catclaw acacia seedlings predominates in revegetation efforts, but catclaw acacia was in a seed mixture used to successfully revegetate a pipeline corridor in Arizona. Using tillage, mulch, and site-adapted seed, the revegetated site closely resembled nearby undisturbed sites 10 years after planting . On an abandoned asbestos milling site in Globe, Arizona, catclaw acacia transplants were 100% successful even given rodent herbivory in the area . Catclaw acacia seedlings survived on a gold mine spoils site in the Mohave Desert. Survival rates were not reported . Catclaw acacia was one of many species used to revegetate disturbed sites (road side cuts, mining sites, eroded hillsides, and gullies) by the Utah Division of Wildlife Resources and other cooperators. In southern desert shrubland areas, catclaw acacia established well when transplanted, spread well by seed, and survived on alkaline or acidic soils. In categories of natural vegetative spread, growth rate, soil stability, and disturbance tolerance, catclaw acacia received mid level ratings .
As transplants are favored over seed, the following insights regarding catclaw acacia
seedling production may prove useful. When growing catclaw acacia seed in containers,
a tall container is recommended to house the rapidly developing root system .
Heydari and others  found the root length of catclaw acacia seedlings was greater
than 23.6 inches (60 cm) 4-5 months after planting on watered sites. Fidelibus and Bainbridge
 found seedling growth and survival were not compromised when bareroot seedlings were
transported to the field site in moist fabric rather than in greenhouse containers.
Indigenous people found several uses for catclaw acacia. The Akimel O'odham or Gila River Pima ate catclaw acacia seeds when better foods were not available; the author considered catclaw acacia a "starvation food" . The Chauilla Native Americans of southern California utilized catclaw acacia wood as fuel and ate catclaw acacia beans. The pods were eaten fresh, dried, or ground into powder; the bitter taste of the pods suggests catclaw acacia was not preferred. However, all Chauilla interviewed recalled catclaw acacia as a food source .
Moore  suggests several other catclaw acacia medicinal properties. Pods are used to make an eyewash to treat conjunctivitis. Leaves and pods when ground into powder will stop small amounts of bleeding and soothe chafed skin or diaper rash. When this powder is made into a tea, it can be used as an antimicrobial wash or drunk to treat diarrhea and dysentery. Native Americans used catclaw acacia to soothe sore flank and back muscles of their horses. The flowers and leaves in tea can treat nausea, vomiting, and hangovers. The thick, sticky catclaw acacia root when made into tea treats sore throats, mouth inflammations, and coughs .
Catclaw acacia wood is strong, hard, tight grained, and heavy [52,74,164]. It is used
for cabinets, turnery, and fencing . The contrasting reddish brown heart wood and
yellow sapwood makes it valuable for making souvenirs .
OTHER MANAGEMENT CONSIDERATIONS:
Catclaw acacia is able to withstand heavy grazing pressure. Defoliated plants showed significantly more shoots (p=0.05), greater branch length (p<0.01), and leaf density (p=0.02) in the current year's growth than did control plants. Following defoliation treatments, plants were undisturbed for 1 year. Branch length of these previously defoliated plants was significantly (p=0.03) less than control plants. Spine density was significantly (p=0.04) greater on defoliated mature plants compared to undisturbed controls .
Many have researched the control of catclaw acacia in once grassland-dominated ecosystems. Mechanical control [23,137], chemical control [70,104,105,117,163], and combined control measures are described .
1. Alford, Eddie J.; Brock, John H. 2002. The effects of fire on Sonoran Desert plant communities. Final Report: RMRS-99164-RJVA. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. 111 p. [Alford's Dissertation]. On file with: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory, Missoula, MT. 
2. Allen, Larry S. 1996. Ecological role of fire in the Madrean Province. In: Ffolliott, Peter F.; DeBano, Leonard F.; Baker, Malchus B., Jr.; Gottfried, Gerald J.; Solis-Garza, Gilberto; Edminster, Carleton B.; Neary, Daniel G.; Allen, Larry S.; Hamre, R. H., tech. coords. Effects of fire on Madrean Province ecosystems: a symposium proceedings; 1996 March 11-15; Tucson, AZ. Gen. Tech. Rep. RM-GTR-289. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station: 5-10. 
3. Anderson, D. J.; Perry, R. A.; Leigh, J. H. 1972. Some perspectives on shrub/environment interactions. In: McKell, Cyrus M.; Blaisdell, James; Goodin, Joe R., tech. eds. Wildland shrubs--their biology and utilization: An international symposium: Proceedings; 1971 July; Logan, UT. Gen. Tech. Rep. INT-1. Ogden, UT: U.S. Department of Agriculture, Forest Service, Intermountain Forest and Range Experiment Station: 172-181. 
4. Anthony, Robert G. 1976. Influence of drought on diets and numbers of desert deer. The Journal of Wildlife Management. 40(1): 140-144. 
5. Anthony, Robert G.; Smith, Norman S. 1977. Ecological relationships between mule deer and white-tailed deer in southeastern Arizona. Ecological Monographs. 47(3): 255-277. 
6. Archer, Steven. 1994. Woody plant encroachment into southwestern grasslands and savannas: rates, patterns and proximate causes. In: Vavra, Martin; Laycock, William A.; Pieper, Rex D., eds. Ecological implications of livestock herbivory in the West. Denver, CO: Society for Range Management: 13-68. 
7. Arno, Stephen F.; Wilson, Andrew E. 1986. Dating past fires in curlleaf mountain-mahogany communities. Journal of Range Management. 39(3): 241-243. 
8. Austin, George T. 1970. Breeding birds of desert riparian habitat in southern Nevada. The Condor. 72: 431-436. 
9. Baldwin, Bruce G.; Goldman, Douglas H.; Keil, David J.; Patterson, Robert; Rosatti, Thomas J.; Wilken, Dieter H., eds. 2012. The Jepson manual. Vascular plants of California, second edition. Berkeley, CA: University of California Press. 1568 p. 
10. Baldwin, Randolph F. 1979. The effects of fire upon vegetation in Joshua Tree National Monument. [Senior thesis report]. Santa Barbara, CA: University of California. Unpublished paper on file at: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory, Missoula, MT. 76 p. 
11. Bean, Lowell John; Saubel, Katherine Siva. 1972. Telmalpakh: Cahuilla Indian knowledge and usage of plants. Banning, CA: Malki Museum. 225 p. 
12. Bernard, Stephen R.; Brown, Kenneth F. 1977. Distribution of mammals, reptiles, and amphibians by BLM physiographic regions and A.W. Kuchler's associations for the eleven western states. Tech. Note 301. Denver, CO: U.S. Department of the Interior, Bureau of Land Management. 169 p. 
13. Blake-Jacobson, M. E. 1987. Stomatal conductance and water relations of shrubs growing at the chaparral-desert ecotone in California and Arizona. In: Tenhunen, J. D.; Catarino, F. M.; Lange, O. L.; Oechel, W. C., eds. Plant response to stress: Functional analysis in Mediterranean ecosystems. NATO ASI Series. Vol. G15: 223-245. 
14. Bonham, Charles D.; Brown, Karla A. 2002. Feral burros and woody plants: an ecological assessment of risks. Rangelands. 24(5): 49-52. 
15. Bowers, Janice E. 2002. Regeneration of triangle-leaf bursage (Ambrosia deltoidea: Asteraceae): germination behavior and persistent seed bank. The Southwestern Naturalist. 47(3): 449-513. 
16. Bowers, Janice E.; McLaughlin, Steven P. 1987. Flora and vegetation of the Rincon Mountains, Pima County, Arizona. Desert Plants. 8(2): 50-94. 
17. Bowers, Janice E.; Webb, Robert H.; Pierson, Elizabeth A. 1997. Succession of desert plants on debris flow terraces, Grand Canyon, Arizona, U.S.A. Journal of Arid Environments. 36(1): 67-86. 
18. Bowers, Janice E.; Webb, Robert H.; Rondeau, Renee J. 1995. Longevity, recruitment and mortality of desert plants in Grand Canyon, Arizona, USA. Journal of Vegetation Science. 6(4): 551-564. 
19. Campbell, Howard; Martin, Donald K.; Ferkovich, Paul E.; Harris, Bruce K. 1973. Effects of hunting and some other environmental factors on scaled quail in New Mexico. Wildlife Monographs No. 34. Bethesda, MD: The Wildlife Society. 49 p. 
20. Carmichael, R. S.; Knipe, O. D.; Pase, C. P.; Brady, W. W. 1978. Arizona chaparral: plant associations and ecology. Res. Pap. RM-202. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station. 16 p. 
21. Cartron, Jean-Luc E.; Stoleson, Scott H.; Russell, Stephen M.; Proudfoot, Glenn A.; Richardson, W. Scott. 2000. The ferruginous pygmy-owl in the tropics and at the northern end of its range: habitat relations and requirements. In: Cartron, Jean-Luc E.; Finch, Deborah M., tech. eds. Ecology and conservation of the cactus ferruginous pygmy-owl in Arizona. Gen. Tech. Rep. RMRS-GTR-43. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station: 47-55. 
22. Cooper, S. M.; Owens, M. K.; Spalinger, D. E.; Ginnett, T. F. 2003. The architecture of shrubs after defoliation and the subsequent feeding behavior of browsers. Oikos. 100(2): 387-393. 
23. Cross, B. T.; Wiedemann, H. T. 1997. Control of catclaw acacia and mimosa by grubbing. Applied Engineering in Agriculture. 13(2): 407-410. 
24. Crow, Taylor; Ritter, Matt. 2012. Changes to the botanical code and what they mean for western North American botany. Madrono. 59(4): 169-170. 
25. Darrow, Robert A. 1944. Arizona range resources and their utilization: 1. Cochise County. Tech. Bull. 103. Tucson, AZ: University of Arizona, Agricultural Experiment Station: 311-364. 
26. Davis, C. A.; Sawyer, P. E.; Griffing, J. P.; Borden, B. D. 1974. Bird populations in a shrub-grassland area, southeastern New Mexico. Bulletin 619. Las Cruces, NM: New Mexico State University, Agricultural Experiment Station. 29 p. 
27. Denyes, H. Arliss. 1956. Natural terrestrial communities of Brewster County, Texas, with special reference to the distribution of the mammals. The American Midland Naturalist. 55(2): 289-320. 
28. Dick-Peddie, William A. 1993. New Mexico vegetation: past, present, and future. Albuquerque, NM: University of New Mexico Press. 244 p. 
29. Dick-Peddie, William A.; Alberico, Michael S. 1977. Fire ecology study of the Chisos Mountains, Big Bend National Park, Texas: Phase I. CDRI Contribution No. 35. Alpine, TX: The Chihuahuan Desert Research Institute. 47 p. 
30. Diggs, George M., Jr.; Lipscomb, Barney L.; O'Kennon, Robert J. 1999. Illustrated flora of north-central Texas. Sida Botanical Miscellany, No. 16. Fort Worth, TX: Botanical Research Institute of Texas. 1626 p. 
31. Drawe, D. Lynn; Higginbotham, Ira, Jr. 1980. Plant communities of the Zachry Ranch in the south Texas plains. Texas Journal of Science. 32: 319-332. 
32. Eddy, Thomas A. 1961. Foods and feeding patterns of the collared peccary in southern Arizona. The Journal of Wildlife Management. 25: 248-257. 
33. Ehleringer, James R.; Cooper, Tamsie A. 1988. Correlations between carbon isotope ratio and microhabitat in desert plants. Oecologia. 76: 562-566. 
34. Erdman, Kimball S. 1961. Distribution of the native trees of Utah. Brigham Young University Science Bulletin: Biological Series. 11(3): 1-34. 
35. Eskew, D. L.; Ting, J. P. 1978. Nitrogen fixation by legumes and blue-green algal-lichen crusts in a Colorado desert environment. American Journal of Botany. 65(8): 850-856. 
36. Esque, Todd C.; Schwalbe, Cecil R. 2002. Alien annual grasses and their relationships to fire and biotic change in Sonoran desertscrub. In: Tellman, Barbara, ed. Invasive exotic species in the Sonoran region. Arizona-Sonora Desert Museum studies in natural history. Tucson, AZ: The University of Arizona Press; The Arizona-Sonora Desert Museum: 165-194. 
37. Everett, Percy C. 1957. A summary of the culture of California plants at the Rancho Santa Ana Botanic Garden 1927-1950. Claremont, CA: The Rancho Santa Ana Botanic Garden. 223 p. 
38. Eyre, F. H., ed. 1980. Forest cover types of the United States and Canada. Washington, DC: Society of American Foresters. 148 p. 
39. Fidelibus, Matthew W.; Bainbridge, David A. 1994. The effect of containerless transport on desert shrubs. Tree Planters' Notes. 45(3): 82-85. 
40. Flora of North America Editorial Committee, eds. 2014. Flora of North America north of Mexico, [Online]. Flora of North America Association (Producer). Available: http://www.efloras.org/flora_page.aspx?flora_id=1. 
41. Foster, J. H.; Krausz, H. B.; Leidigh, A. H. 1917. General survey of Texas woodlands including a study of the commercial possibilities of mesquite. Bulletin of the Agricultural and Mechanical College of Texas. Bulletin 3: Department of Forestry. Third Series 3(9): 1-47. 
42. Garcia-Moya, Edmondo; McKell, Cyrus M. 1970. Contribution of shrubs to the nitrogen economy of a desert-wash plant community. Ecology. 51(1): 81-88. 
43. Garrison, George A.; Bjugstad, Ardell J.; Duncan, Don A.; Lewis, Mont E.; Smith, Dixie R. 1977. Vegetation and environmental features of forest and range ecosystems. Agric. Handb. 475. Washington, DC: U.S. Department of Agriculture, Forest Service. 68 p. 
44. Gibson, Arthur C. 1998. Photosynthetic organs of desert plants. BioScience. 48(11): 911-913, 916-920. 
45. Gionfriddo, James P.; Krausman, Paul R. 1986. Summer habitat use by mountain sheep. The Journal of Wildlife Management. 50(2): 331-336. 
46. Goodwin, John G., Jr.; Hungerford, C. Roger. 1977. Habitat use by native Gambel's and scaled quail and released masked bobwhite quail in southern Arizona. Res. Pap. RM-197. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station. 8 p. 
47. Gullion, Gordon W. 1960. The ecology of Gambel's quail in Nevada and the arid Southwest. Ecology. 41(3): 518-536. 
48. Gullion, Gordon W. 1964. Wildlife uses of Nevada plants. Contributions toward a flora of Nevada: No. 49. CR-24-64. Beltsville, MD: U.S. Department of Agriculture, Agricultural Research Service, Crops Research Division; Washington, DC: U.S. National Arboretum, Herbarium. 170 p. 
49. Haigh, Sandra L. 1998. Stem diameter-age relationships of Tamarix ramosissima on lake shore and stream sites in southern Nevada. The Southwestern Naturalist. 43(4): 425-429. 
50. Harris, Lisa K.; Ruther, Sherry. 2000. Ecological characteristics of riparian washes in southeastern Arizona, USA. Natural Areas Journal. 20(3): 221-226. 
51. Hastings, James R.; Turner, Raymond M.; Warren, Douglas K. 1972. An atlas of some plant distributions in the Sonoran Desert. Technical Reports on the Meteorology and Climatology of Arid Regions: No. 21. Tucson, AZ: University of Arizona, Institute of Atmospheric Physics. 255 p. 
52. Havard, V. 1885. Report on the flora of western and southern Texas. Proceedings of the United States National Museum. 8(29): 449-533. 
53. Henrickson, James; Johnston, Marshall C. 1986. Vegetation and community types of the Chihuahuan Desert. In: Barlow, Jon C.; Powell, A. Michael; Timmermann, Barbara N., eds. Chihuahuan Desert--U.S. and Mexico, II: Proceedings of the 2nd symposium on resources of the Chihuahuan Desert region; 1983 October 20-21; Alpine, TX. Alpine, TX: Sul Ross State University, Chihuahuan Desert Research Institute: 20-39. 
54. Heydari, Hossein; Roundy, Bruce A.; Watson, Carolyn; Smith, Steven E.; Munda, Bruce; Pater, Mark. 1996. Summer establishment of four Sonoran Desert shrubs using line source sprinkler irrigation. In: Barrow, Jerry R.; McArthur, E. Durant; Sosebee, Ronald E.; Tausch, Robin J., compilers. Proceedings: shrubland ecosystem dynamics in a changing environment; 1995 May 23-25; Las Cruces, NM. Gen. Tech. Rep. INT-GTR-338. Ogden, UT: U.S. Department of Agriculture, Forest Service, Intermountain Research Station: 129-134. 
55. Hibbert, Alden R.; Davis, Edwin A.; Scholl, David G. 1974. Chaparral conversion potential in Arizona. Part I: water yield response and effects on other resources. Res. Pap. RM-126. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station. 36 p. 
56. Hickman, James C., ed. 1993. The Jepson manual: Higher plants of California. Berkeley, CA: University of California Press. 1400 p. 
57. Holland, Robert F. 1986. Preliminary descriptions of the terrestrial natural communities of California. Sacramento, CA: California Department of Fish and Game. 156 p. 
58. Humphrey, R. R. 1950. Arizona range resources: II. Yavapai County. Bull. 229. Tucson, AZ: University of Arizona, Agricultural Experiment Station. 55 p. 
59. Humphrey, Robert R. 1953. Forage production on Arizona ranges: III. Mohave County: A study in range condition. Bulletin 244. Tucson, AZ: University of Arizona, Agricultural Experiment Station. 79 p. 
60. Humphrey, Robert R. 1958. The desert grassland: A history of vegetational change and an analysis of causes. The Botanical Review. 24(4): 193-252. 
61. Humphrey, Robert R. 1960. Forage production on Arizona ranges. V. Pima, Pinal and Santa Cruz Counties. Bulletin 502. Tucson, AZ: University of Arizona, Agricultural Experiment Station. 137 p. 
62. Humphrey, Robert R. 1974. Fire in the deserts and desert grassland of North America. In: Kozlowski, T. T.; Ahlgren, C. E., eds. Fire and ecosystems. New York: Academic Press: 365-400. 
63. Humphrey, Robert Regester. 1962. Fire as a factor. In: Humphrey, Robert Regester. Range ecology. New York: Ronald Press: 148-189. 
64. Huston, J. E.; Rector, B. S.; Merrill, L. B.; Engdahl, B. S. 1981. Nutritional value of range plants in the Edwards Plateau region of Texas. Report B-1375. College Station, TX: Texas A&M University System, Texas Agricultural Experiment Station. 16 p. 
65. James, Richard D. 1998. Use of native species in revegetation of disturbed sites (Arizona). In: Tellman, Barbara; Finch, Deborah M.; Edminster, Carl; Hamre, Robert, eds. The future of arid grasslands: identifying issues, seeking solutions: Proceedings; 1996 October 9-13; Tucson, AZ. Proceedings RMRS-P-3. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station: 297-303. 
66. Johnson, Carl M. 1970. Common native trees of Utah. Special Report 22. Logan, UT: Utah State University, College of Natural Resources, Agricultural Experiment Station. 109 p. 
67. Johnson, Hyrum B. 1976. Vegetation and plant communities of southern California deserts--a functional view. In: Latting, June, ed. Symposium proceedings: plant communities of southern California; 1974 May 4; Fullerton, CA. Special Publication No. 2. Berkeley, CA: California Native Plant Society: 125-164. 
68. Johnson, M. C. 1974. Acacia emoryana in Texas and Mexico and its relationship to A. berlandieri and A. greggii. The Southwestern Naturalist. 19: 331-333. 
69. Jones, Stanley D.; Wipff, Joseph K.; Montgomery, Paul M. 1997. Vascular plants of Texas. Austin, TX: University of Texas Press. 404 p. 
70. Jones, V. E.; Meadors, C. H.; Jacoby, P. W.; Fisher, C. E. 1978. Effect of pelleted herbicides on six hard to control brush species. In: Herbicides: the cost/benefit ratio: 31st annual meeting of the Southern Weed Science Society; 1978 January 17-19; New Orleans, LA. In: Proceedings, Southern Weed Science Society. Auburn, AL: Southern Weed Science Society; 31: 191. 
71. Jordan, Gilbert L.; Haferkamp, Marshal R. 1989. Temperature responses and calculated heat units for germination of several range grasses and shrubs. Journal of Range Management. 42(1): 41-45. 
72. Kartesz, J. T.; The Biota of North America Program (BONAP). 2014. North American plant atlas, [Online]. Chapel Hill, NC: The Biota of North America Program (Producer). Available: http://bonap.org/. [Maps generated from Kartesz, J. T. 2010. Floristic synthesis of North America, Version 1.0. Biota of North America Program (BONAP). [In press]. 
73. Kartesz, John T. 1999. A synonymized checklist and atlas with biological attributes for the vascular flora of the United States, Canada, and Greenland. 1st ed. In: Kartesz, John T.; Meacham, Christopher A. Synthesis of the North American flora (Windows Version 1.0), [CD-ROM]. Chapel Hill, NC: North Carolina Botanical Garden (Producer). In cooperation with: The Nature Conservancy; U.S. Department of Agriculture, Natural Resources Conservation Service; U.S. Department of the Interior, Fish and Wildlife Service. 
74. Kearney, Thomas H.; Peebles, Robert H.; Howell, John Thomas; McClintock, Elizabeth. 1960. Arizona flora. 2nd ed. Berkeley, CA: University of California Press. 1085 p. 
75. Krausman, Paul R.; Kuenzi, Amy J.; Etchberger, Richard C.; Rautenstrauch, Kurt T.; Ordway, Leonard L.; Hervert, John J. 1997. Diets of mule deer. Journal of Range Management. 50(5): 513-522. 
76. Krausman, Paul R.; Ordway, Leonard L.; Whiting, Frank M.; Brown, William H. 1990. Nutritional composition of desert mule deer forage in the Picacho Mountains, Arizona. Desert Plants. 10(1): 32-34. 
77. Kucera, Clair L. 1981. Grasslands and fire. In: Mooney, H. A.; Bonnicksen, T. M.; Christensen, N. L.; Lotan, J. E.; Reiners, W. A., tech. coords. Fire regimes and ecosystem properties: Proceedings of the conference; 1978 December 11-15; Honolulu, HI. Gen. Tech. Rep. WO-26. Washington, DC: U.S. Department of Agriculture, Forest Service: 90-111. 
78. Kuchler, A. W. 1964. United States [Potential natural vegetation of the conterminous United States]. Special Publication No. 36. New York: American Geographical Society. 1:3,168,000; colored. 
79. Ladyman, Juanita A. R. 2004. Acacia greggii. In: Francis, John K., ed. Wildland shrubs of the United States and its territories: thamnic descriptions: volume 1. Gen. Tech. Rep. IITF-GTR-26. San Juan, PR: U.S. Department of Agriculture, Forest Service, International Institute of Tropical Forestry; Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station: 16-17. 
80. Leary, Patrick J. 1979. A study of vegetational reinvasion following natural fire in Joshua Tree National Monument: I. Preliminary report. Contribution Number CPSU/UNLV No. 019/01. Las Vegas, NV: University of Nevada, Department of Biological Sciences, Cooperative National Park Resources Studies Unit. 34 p. Unpublished report on file with: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory, Missoula, MT. 
81. Lei, Simon A. 2001. Survival and development of Phoradendron californicum and Acacia Greggii during a drought. Western North American Naturalist. 61(1): 78-84. 
82. Lei, Simon A.; Walker, Lawrence R. 1997. Classification and ordination of Coleogyne communities in southern Nevada. The Great Basin Naturalist. 57(2): 155-162. 
83. Leopold, A. Starker. 1950. Vegetation zones of Mexico. Ecology. 31(4): 507-518. 
84. Levin, Geoffrey A. 1988. How plants survive in the desert. Environment Southwest. Summer: 20-25. 
85. Little, Elbert L., Jr. 1950. Southwestern trees: A guide to the native species of New Mexico and Arizona. Agric. Handb. No. 9. Washington, DC: U.S. Department of Agriculture, Forest Service. 109 p. 
86. Little, Elbert L., Jr. 1979. Checklist of United States trees (native and naturalized). Agric. Handb. 541. Washington, DC: U.S. Department of Agriculture, Forest Service. 375 p. 
87. Lopez-Trujillo, R.; Garcia-Elizondo, R. 1995. Botanical composition and diet quality of goats grazing natural and grass reseeded shrublands. Small Ruminant Research. 16(1): 37-47. 
88. Losher, Lee. 1993. Propagation, revegetation program underway at Organ Pipe National Monument. Restoration and Management Notes. 11(2): 166-167. 
89. Lowe, Charles H., Jr. 1961. Biotic communities in the sub-Mogollon region of the Inland Southwest. Arizona Academy of Science Journal. 2: 40-49. 
90. MacMahon, James A. 1988. Warm deserts. In: Barbour, Michael G.; Billings, William Dwight, eds. North American terrestrial vegetation. New York: Cambridge University Press: 231-264. 
91. Marks, John Brady. 1950. Vegetation and soil relations in the lower Colorado Desert. Ecology. 31: 176-193. 
92. Martin, S. Clark. 1975. Ecology and management of southwestern semidesert grass-shrub ranges: the status of our knowledge. Res. Pap. RM-156. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station. 39 p. 
93. Martin, William C.; Hutchins, Charles R. 1981. A flora of New Mexico. Volume 2. Germany: J. Cramer. 2589 p. 
94. McAuliff, J. R. 1995. The aftermath of wildfire in the Sonoran Desert. The Sonoran Quarterly. 49: 4-8. 
95. McCulloch, Clay Y. 1973. Part I: Seasonal diets of mule and white-tailed deer. In: Deer nutrition in Arizona chaparral and desert habitats. Special Report No. 3: Federal Aid in Wildlife Restoration Act Project W-78-R. Phoenix, AZ: Arizona Game and Fish Department, Research Division: 1-37. In cooperation with: U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station. 
96. McPherson, Guy R. 1995. The role of fire in the desert grasslands. In: McClaran, Mitchel P.; Van Devender, Thomas R., eds. The desert grassland. Tucson, AZ: The University of Arizona Press: 130-151. 
97. McPherson, Guy R.; Wright, Henry A. 1989. Direct effects of competition on individual juniper plants: a field study. Journal of Applied Ecology. 26(3): 979-988. 
98. McPherson, Guy R.; Wright, Henry A. 1990. Establishment of Juniperus pinchotii in western Texas: environmental effects. Journal of Arid Environments. 19(3): 283-287. 
99. Meadors, C. H.; Fisher, C. E.; Haas, R. H.; Hoffman, G. O. 1973. Combinations of methods and maintenance control of mesquite. In: Mesquite: Growth and development, management, economics, control, uses. Research Monograph 1. College Station, TX: Texas A&M University, The Texas Agricultural Experiment Station: 53-59. 
100. Milton, Suzanne J.; Dean, W. R. J.; Kerley, G. I. H.; Hoffman, M. T.; Whitford, W. G. 1998. Dispersal of seeds as nest material by the cactus wren. The Southwestern Naturalist. 43(4): 449-452. 
101. Minckley, W. L. 1992. Three decades near Cuatro Cienegas, Mexico: photographic documentation and a plea for area conservation. Journal of the Arizona-Nevada Academy of Science. 26(2): 89-118. 
102. Monson, Gale; Kessler, Wayne. 1940. Life history notes on the banner-tailed kangaroo rat, Merriam's kangaroo rat, and white-throated wood rat in Arizona and New Mexico. The Journal of Wildlife Management. 4(1): 37-43. 
103. Moore, Michael. 1989. Medicinal plants of the desert and canyon West. Santa Fe, NM: Museum of New Mexico Press. 184 p. 
104. Morton, Howard L. 1984. Influence of tebuthiuron formulation on control of woody plants and forage production. Proceedings, Western Society of Weed Science. [Volume unknown]: 129-138. 
105. Morton, Howard, L.; Metto, Paul; Ogden, Phil R. 1971. Catclaw control in southern Arizona. Proceedings of the Western Society of Weed Science. 24: 12-13. 
106. Muller, Cornelius H. 1940. Plant succession in the Larrea-Flourensia climax. Ecology. 21: 206-212. 
107. Munz, Philip A. 1974. A flora of southern California. Berkeley, CA: University of California Press. 1086 p. 
108. Murie, Adolph. 1951. Coyote food habits on a southwestern cattle range. Journal of Mammalogy. 32(3): 291-295. 
109. Neff, Don J. 1974. Forage preferences of trained deer on the Beaver Creek watersheds. Special Report No. 4. Phoenix, AZ: Arizona Game and Fish Department. 61 p. 
110. Niering, William A.; Lowe, Charles H. 1984. Vegetation of the Santa Catalina Mountains: community types and dynamics. Vegetatio. 58: 3-28. 
111. Nilsen, Erik Tallak; Sharifi, M. Rasoul; Rundel, Philip W. 1984. Comparative water relations of phreatophytes in the Sonoran Desert of California. Ecology. 65(3): 767-778. 
112. Ockenfels, Richard A. 1994. Mountain lion predation on pronghorn in central Arizona. The Southwestern Naturalist. 39(3): 305-306. 
113. Ohmart, Robert D.; Anderson, Bertin W. 1982. North American desert riparian ecosystems. In: Bender, Gordon L., ed. Reference handbook on the deserts of North America. Westport, CT: Greenwood Press: 433-479. 
114. Owens, M. K.; Schliesing, T. G. 1995. Invasive potential of Ashe juniper after mechanical disturbance. Journal of Range Management. 48: 503-507. 
115. Owens, M. Keith; Mackley, J. W.; Carroll, C. J. 2002. Vegetation dynamics following seasonal fires in mixed mesquite/acacia savannas. Journal of Range Management. 55(5): 509-516. 
116. Parker, Kathleen C. 1986. Partitioning of foraging space and nest sites in a desert shrubland bird community. The American Midland Naturalist. 115(2): 255-267. 
117. Parker, Robert, compiler. 1982. Reaction of various plants to 2,4-D, MCPA, 2,4,5-T, silvex and 2,4-DB. EM 4419 [Revised]. Pullman, WA: Washington State University, College of Agriculture, Cooperative Extension. 61 p. In cooperation with: U.S. Department of Agriculture. 
118. Paysen, Timothy E.; Ansley, R. James; Brown, James K.; Gottfried, Gerald J.; Haase, Sally M.; Harrington, Michael G.; Narog, Marcia G.; Sackett, Stephen S.; Wilson, Ruth C. 2000. Fire in western shrubland, woodland, and grassland ecosystems. In: Brown, James K.; Smith, Jane Kapler, eds. Wildland fire in ecosystems: Effects of fire on flora. Gen. Tech. Rep. RMRS-GTR-42-vol. 2. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station: 121-159. 
119. Pemberton, Robert W. 1988. The abundance of plants bearing extrafloral nectaries in Colorado and Mojave Desert communities of southern California. Madrono. 35(3): 238-246. 
120. Perkins, Steven R.; Owens, M. Keith. 2003. Growth and biomass allocation of shrub and grass seedlings in response to predicted changes in precipitation seasonality. Plant Ecology. 168(1): 107-120. 
121. Perry, Hazel M.; Aldon, Earl F.; Brock, John H. 1987. Reclamation of an asbestos mill waste site in the southwestern United States. Reclamation and Revegetation Research. 6: 187-196. 
122. Phillips, Barbara G. 1992. Status of non-native plant species, Tonto National Monument, Arizona. Technical Report NPS/WRUA/NRTR-92/46. Tucson, AZ: The University of Arizona, School of Renewable Natural Resources, Cooperative National Park Resources Study Unit. 25 p. 
123. Pierson, Elizabeth A.; McAuliffe, Joseph R. 1995. Characteristics and consequences of invasion by sweet resin bush into the arid southwestern United States. In: DeBano, Leonard H.; Ffolliott, Peter H.; Ortega-Rubio, Alfredo; Gottfried, Gerald J.; Hamre, Robert H.; Edminster, Carleton B., tech. coords. Biodiversity and management of the Madrean Archipelago: the sky islands of southwestern United States and northwestern Mexico: Proceedings; 1994 September 19-23; Tucson, AZ. Gen. Tech. Rep. RM-GRT-264. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station: 219-230. 
124. Plummer, A. Perry. 1977. Revegetation of disturbed Intermountain area sites. In: Thames, J. C., ed. Reclamation and use of disturbed lands of the Southwest. Tucson, AZ: University of Arizona Press: 302-337. 
125. Powell, A. Michael. 1988. Trees and shrubs of Trans-Pecos Texas: Including Big Bend and Guadalupe Mountains National Parks. Big Bend National Park, TX: Big Bend Natural History Association. 536 p. 
126. Ramirez, R. G.; Haenlein, G. F. W.; Nunez-Gonzalez, M. A. 2001. Seasonal variation of macro and trace mineral contents in 14 browse species that grow in northeastern Mexico. Small Ruminant Research. 39(2): 153-159. 
127. Ramirez, R. G.; Ledezma-Torres, R. A.; Pena-Hernandez, A. F.; Moreno-Villanueva, R. 1998. Dry matter and protein degradation of foliage from Medicago sativa, Acacia greggii and Prosopis glandulosa by sheep. Phyton: International Journal of Experimental Botany. 62(1-2): 131-135. 
128. Ramirez, R. G.; Sauceda, J. G.; Narro, J. A.; Aranda, J. 1993. Preference indices for forage species grazed by Spanish goats on a semiarid shrubland in Mexico. Journal of Applied Animal Research. 3(1): 55-66. 
129. Raunkiaer, C. 1934. The life forms of plants and statistical plant geography. Oxford: Clarendon Press. 632 p. 
130. Rautenstrauch, Kurt R.; Krausman, Paul R.; Whiting, Frank M.; Brown, William H. 1988. Nutritional quality of desert mule deer forage in King Valley, Arizona. Desert Plants. 8(4): 172-174. 
131. Rea, Amadeo M. 1991. Gila River Pima dietary reconstruction. Arid Lands Newsletter. 31: 3-10. 
132. Reynolds, Hudson G. 1958. The ecology of the Merriam kangaroo rat (Dipodomys merriami Mearns) on the grazing lands of southern Arizona. Ecological Monographs. 28(9): 111-127. 
133. Rogers, Garry F.; Steele, Jeff. 1980. Sonoran Desert fire ecology. In: Stokes, Marvin A.; Dieterich, John H., technical coordinators. Proceedings of the fire history workshop; 1980 October 20-24; Tucson, AZ. Gen. Tech. Rep. RM-81. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station: 15-19. 
134. Rowe, J. S. 1969. Lightning fires in Saskatchewan grassland. The Canadian Field-Naturalist. 83: 317-324. 
135. Rowlands, Peter G. 1980. Recovery, succession, and revegetation in the Mojave Desert. In: Rowlands, Peter G., ed. The effects of disturbance on desert soils, vegetation and community processes with emphasis on off road vehicles: a critical review. Special Publication. Riverside, CA: U.S. Department of the Interior, Bureau of Land Management, Desert Plan Staff: 75-120. 
136. Ruthven, Donald C., III; Braden, Anthony W.; Knutson, Haley J.; Gallagher, James F.; Synatzske, David R. 2003. Woody vegetation response to various burning regimes in South Texas. Journal of Range Management. 56(2): 159-166. 
137. Ruthven, Donald C., III; Krakauer, Keith L. 2004. Vegetation response of a mesquite-mixed brush community to aeration. Journal of Range Management. 57(1): 34-40. 
138. Schultz, Brad W. 1987. Ecology of curlleaf mountain mahogany (Cercocarpus ledifolius) in western and central Nevada: population structure and dynamics. Reno, NV: University of Nevada. 111 p. Thesis. 
139. Scott, Norman J., Jr. 1979. The impact of grazing on wildlife, Kofa National Wildlife Refuge, Yuma County, Arizona. Final Report. Albuquerque, NM: U.S. Department of the Interior, Fish and Wildlife Service. 70 p. 
140. Seegmiller, Rick F.; Krausman, Paul R.; Brown, William H.; Whiting, Frank M. 1990. Nutritional composition of desert bighorn sheep forage in the Harquahala Mountains, Arizona. Desert Plants. 10(2): 87-90. 
141. Seigler, D. S.; Seilheimer, S.; Keesy, J.; Huang, H. F. 1986. Tannins from four common Acacia species of Texas and northeastern Mexico. Economic Botany. 40(2): 220-232. 
142. Shiflet, Thomas N., ed. 1994. Rangeland cover types of the United States. Denver, CO: Society for Range Management. 152 p. 
143. Short, Henry L. 1977. Food habits of mule deer in a semi-desert grass-shrub habitat. Journal of Range Management. 30: 206-209. 
144. Smith, H. N.; Rechenthin, C. A. 1965. Grassland restoration: The Texas brush problem. Temple, TX: U.S. Department of Agriculture, Soil Conservation Service. 33 p. 
145. Steuter, Allen A.; Wright, Henry A. 1983. Spring burning effects on redberry juniper-mixed grass habitats. Journal of Range Management. 36(2): 161-164. 
146. Stickney, Peter F. 1989. Seral origin of species comprising secondary plant succession in northern Rocky Mountain forests. FEIS workshop: Postfire regeneration. Unpublished draft on file at: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory, Missoula, MT. 10 p. 
147. Stuever, Mary C.; Hayden, John S. 1996. Plant associations (habitat types) of the forests and woodlands of Arizona and New Mexico. Final report: Contract R3-95-27. Placitas, NM: Seldom Seen Expeditions. 520 p. 
148. Tewksbury, Joshua Jordan; Nabhan, Gary Paul; Norman, Donald; Suzan, Humberto; Tuxill, John; Donovan, Jim. 1999. In situ conservation of wild chiles and their biotic associates. Conservation Biology. 13(1): 98-107. 
149. Texas Natural Heritage Program. 1993. Plant communities of Texas (Series level). Austin, TX: Texas Parks and Wildlife Department. Unpublished report on file at: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory, Missoula, MT. 26 p. 
150. Thornber, J. J. 1910. The grazing ranges of Arizona. Bull. No. 65. Tucson, AZ: University of Arizona, Agricultural Experiment Station. 360 p. 
151. Thorne, Robert F. 1976. The vascular plant communities of California. In: Latting, June, ed. Symposium proceedings: plant communities of southern California; 1974 May 4; Fullerton, CA. Special Publication No. 2. Berkeley, CA: California Native Plant Society: 1-31. 
152. Tomoff, Carl S. 1974. Avian species diversity in desert scrub. Ecology. 55: 396-403. 
153. Tratz, Wallace Michael. 1978. Postfire vegetational recovery, productivity, and herbivore utilization of a chaparral-desert ecotone. Los Angeles, CA: California State University. 133 p. Thesis. 
154. Turkowski, Frank J. 1975. Dietary adaptability of the desert cottontail. The Journal of Wildlife Management. 39(4): 748-756. 
155. Turner, Raymond M.; Brown, David E. 1982. Sonoran desertscrub. In: Brown, David E., ed. Biotic communities of the American Southwest--United States and Mexico. Desert Plants. 4(1-4): 181-221. 
156. U.S. Department of Agriculture, Natural Resources Conservation Service. 2014. PLANTS Database, [Online]. Available: http://plants.usda.gov/. 
157. Ueckert, D. N.; Whisenant, S. G. 1980. Chaining/prescribed burning system for improvement of rangeland infested with mesquite and other undesirable plants. In: Rangeland Resources Research. PR-3665. College Station, TX: Texas Agricultural Experiment Station: 25. 
158. Urness, P. J.; McCulloch, C. Y. 1973. Part III: Nutritional value of seasonal deer diets. In: Deer nutrition in Arizona chaparral and desert habitats. Special Report No. 3: Federal Aid in Wildlife Restoration Act Project W-78-R. Phoenix, AZ: Arizona Game and Fish Department, Research Division: 53-68. In cooperation with: U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station. 
159. Urness, Philip J. 1973. Part II: Chemical analyses and in vitro digestibility of seasonal deer forages. In: Deer nutrition in Arizona chaparral and desert habitats. Special Report No. 3: Federal Aid in Wildlife Restoration Act Project W-78-R. Phoenix, AZ: Arizona Game and Fish Department, Research Division: 39-52. In cooperation with: U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station. 
160. Utah Division of Wildlife Resources. 1998. Inventory of sensitive species and ecosystems in Utah--Endemic and rare plants of Utah: an overview of their distribution and status. Central Utah Project Completion Act: Title III, Section 306(b); Cooperative Agreement No. UC-95-0015: Section V.A.10.a. Salt Lake City, UT: Utah Reclamation, Mitigation and Conservation Commission. 566 p. (+ appendices). 
161. Valone, Thomas J.; Kelt, Douglas A. 1999. Fire and grazing in a shrub-invaded arid grassland community: independent or interactive ecological effects? Journal of Arid Environments. 42(1): 15-28. 
162. Van Devender, Thomas R.; Felger, Richard S.; Burquez M., Alberto. 1997. Exotic plants in the Sonoran Desert region, Arizona and Sonora. In: Kelly, M.; Wagner, E.; Warner, P., eds. Proceedings, California Exotic Pest Plant Council symposium; 1997 October 2-4; Concord, CA. Volume 3. Berkeley, CA: California Exotic Pest Plant Council: 10-15. 
163. Vanzant, Thomas J., III; Kinucan, Robert J.; McGinty, W. Allan. 1997. Mixed-brush reestablishment following herbicide treatment in the Davis Mountains, west Texas. Texas Journal of Agriculture and Natural Resources. 10: 15-23. 
164. Vines, Robert A. 1960. Trees, shrubs, and woody vines of the Southwest. Austin, TX: University of Texas Press. 1104 p. 
165. Vorhies, Charles T.; Taylor, Walter P. 1933. The life histories and ecology of jack rabbits, Lepus alleni and Lepus californicus ssp., in relation to grazing in Arizona. Technical Bulletin No. 49. Tucson, AZ: University of Arizona, Agricultural Experiment Station. 117 p. 
166. Wade, Dale D.; Brock, Brent L.; Brose, Patrick H.; Grace, James B.; Hoch, Greg A.; Patterson, William A., III. 2000. Fire in eastern ecosystems. In: Brown, James K.; Smith, Jane Kapler, eds. Wildland fire in ecosystems: Effects of fire on flora. Gen. Tech. Rep. RMRS-GTR-42-vol. 2. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station: 53-96. 
167. Wallmo, O. C. 1956. Ecology of scaled quail in west Texas. Contribution of the Federal Aid in Wildlife Restoration Act: Special report from Project W-57-R and the Department of Wildlife Management, A & M College of Texas. Austin, TX: Texas Game and Fish Commission, Division of Wildlife Restoration. 134 p. 
168. Warren, Peter L.; Anderson, L. Susan. 1985. Gradient analysis of a Sonoran Desert wash. In: Johnson, R. Roy; [and others], technical coordinators. Riparian ecosystems and their management: reconciling conflicting issues: Proceedings, 1st North American riparian conference; 1985 April 16-18; Tucson, AZ. Gen. Tech. Rep. RM-120. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station: 150-155. 
169. Wauer, Roland H. 1971. Ecological distribution of birds of the Chisos Mountains, Texas. The Southwestern Naturalist. 16(1): 1-29. 
170. Welsh, Stanley L.; Atwood, N. Duane; Goodrich, Sherel; Higgins, Larry C., eds. 1987. A Utah flora. The Great Basin Naturalist Memoir No. 9. Provo, UT: Brigham Young University. 894 p. 
171. Went, F. W. 1948. Ecology of desert plants. I. Observations on germination in the Joshua Tree National Monument, California. Ecology. 29(3): 242-253. 
172. Wester, David B.; Wright, Henry A. 1987. Ordination of vegetation change in Guadalupe Mountains, New Mexico, USA. Vegetatio. 72: 27-33. 
173. Whitfield, Charles J.; Anderson, Hugh L. 1938. Secondary succession in the desert plains grassland. Ecology. 19(2): 171-180. 
174. Wiens, John F. 2000. Vegetation and flora of Ragged Top, Pima County, Arizona. Desert Plants. 16(2): 3-31. 
175. Wiggins, Ira L. 1980. Flora of Baja California. Stanford, CA: Stanford University Press. 1025 p. 
176. Wilson, R. C.; Narog, M. G.; Koonce, A. L.; Corcoran, B. M. 1995. Postfire regeneration in Arizona's giant saguaro shrub community. In: DeBano, Leonard H.; Ffolliott, Peter H.; Ortega-Rubio, Alfredo; Gottfried, Gerald J.; Hamre, Robert H.; Edminster, Carleton B., tech. coords. Biodiversity and management of the Madrean Archipelago: the sky islands of southwestern United States and northwestern Mexico: Proceedings; 1994 September 19-23; Tucson, AZ. Gen. Tech. Rep. RM-GRT-264. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station: 424-431. 
177. Wright, Henry A.; Bailey, Arthur W. 1982. Fire ecology: United States and southern Canada. New York: John Wiley & Sons. 501 p. 
178. Zedler, Paul H. 1981. Vegetation change in chaparral and desert communities in San Diego County, California. In: West, D. C.; Shugart, H. H.; Botkin, D. B., eds. Forest succession: concepts and application. New York: Springer-Verlag: 406-430. 
179. Zimmermann, Robert C. 1969. Plant ecology of an arid basin: Tres Alamos-Redington Area, southeastern Arizona. Geological Survey Professional Paper 485-D. Washington, DC: U.S. Department of the Interior, Geological Survey. 51 p. 
180. Zisner, Cindy D. 1999. Seedling identification and phenology of selected Sonoran Desert dicotyledonous trees and shrubs. Journal of the Arizona-Nevada Academy of Science. 32(2): 129-154. 
181. Zitzer, S. F.; Archer, S. R.; Boutton, T. W. 1996. Spatial variability in the potential for symbiotic N2 fixation by woody plants in a subtropical savanna ecosystem. Journal of Applied Ecology. 33(5): 1125-1136. 
FEIS Home Page