Print Report
A0791 Quercus oblongifolia Scrub Woodland Alliance
Type Concept Sentence: This scrub woodland alliance is characterized by an open to moderately dense (10-60% cover), broad-leaved evergreen tree layer (encinal) dominated by Quercus oblongifolia with herbaceous understory composed of perennial grasses. It is found in southeastern Arizona and northern Mexico occurring on sites ranging from gently to moderately sloping alluvial plains and bajadas to steep rocky slopes in canyons, foothills and mountains.
Common (Translated Scientific) Name: Mexican Blue Oak Scrub Woodland Alliance
Colloquial Name: Mexican Blue Oak Scrub Woodland
Hierarchy Level: Alliance
Type Concept: The vegetation of this scrub woodland alliance is characterized by an open to moderately dense (10-60% cover), short, broad-leaved evergreen tree/tall-shrub layer (encinal) dominated by Quercus oblongifolia with a grass-dominated understory. The oak-dominated tree canopy is typically 3-5 m tall, but may extend beyond 5 m. Juniperus deppeana, Quercus arizonica, Quercus emoryi, Prosopis spp., and occasional Pinus discolor may be present in the tree canopy. Shrubs and rosette succulents and cacti may be scattered or form open to moderately dense layers, including Acacia constricta, Agave palmeri, Arctostaphylos pungens, Brickellia spp., Dasylirion spp., Ericameria laricifolia, Eriogonum wrightii, Eysenhardtia orthocarpa, Garrya wrightii, Mimosa aculeaticarpa var. biuncifera, Mimosa dysocarpa, Nolina microcarpa, Opuntia phaeacantha, Cylindropuntia spinosior, Rhus trilobata, and Yucca madrensis. The graminoid layer typically characterizes the understory, ranges from sparse to dense (5-80% cover), and is typically dominated by medium-tall bunchgrasses such as Bouteloua curtipendula, Schizachyrium cirratum, or Muhlenbergia emersleyi, but it can also be very diverse. Other common graminoids may include Aristida ternipes, Bothriochloa barbinodis, Bouteloua chondrosioides, Bouteloua eriopoda, Bouteloua gracilis, Bouteloua hirsuta, Eragrostis intermedia, Leptochloa dubia, Muhlenbergia longiligula, and Piptochaetium fimbriatum. The usually sparse, but often diverse, forb layer is composed of species of Artemisia, Commelina, Chenopodium, Evolvulus, Hybanthus, Ipomoea, Mirabilis, Viguiera, and many others. Stands occur in southeastern Arizona and northern Mexico on gently to moderately sloping alluvial plains and bajadas to steep rocky slopes in canyons, foothills and mountains. Aspects are variable, but it appears more common on less xeric northern aspects in drier portions of its range. Soils are gravelly or stony sandy loams or sandy clay loams, derived from a mixture of alluvium and colluvium.
Diagnostic Characteristics: Diagnostic characteristics of this alliance include the dominance of the evergreen oak Quercus oblongifolia as the differential species. Understory layers are variable, ranging from sparse to dense grass or shrub layers. Characteristic understory species include desert shrubs such as Acacia constricta, Agave palmeri, Arctostaphylos pungens, Dasylirion wheeleri, Eysenhardtia orthocarpa, Mimosa aculeaticarpa var. biuncifera, Mimosa dysocarpa, Nolina microcarpa, Cylindropuntia spinosior, and Yucca madrensis, and desert grasses such as Aristida ternipes, Bouteloua chondrosioides, Bouteloua eriopoda, Bothriochloa barbinodis, Eragrostis intermedia, Leptochloa dubia, Muhlenbergia emersleyi, Muhlenbergia longiligula, Piptochaetium fimbriatum, and Schizachyrium cirratum.
Rationale for Nominal Species or Physiognomic Features: No Data Available
Classification Comments: This encinal alliance was changed from a shrubland to woodland alliance. Mature Quercus oblongifolia individuals are 7-8 m (20-25 feet) tall. The shrubland classification is not well-supported. Stuever and Hayden (1997a) treat this association as a Quercus oblongifolia / Bouteloua spp. savanna or open woodland habitat type. Kearney et al. (1969) describe Quercus oblongifolia as a small tree that can mature as a shrub at higher elevations. Niering and Lowe (1984) describe an "Open oak woodland" (10-20% cover) that occurs at 1300-1700 m elevation in the Santa Catalina Mountains and is dominated by scattered Quercus oblongifolia with Quercus emoryi and Juniperus deppeana. Open stands with a dense graminoid layer may resemble a tree savanna. More research is needed to fully characterize this alliance, but it is better represented as a short woodland alliance rather than a shrubland alliance.
Similar NVC Types: No Data Available
note: No Data Available
Physiognomy and Structure: Vegetation in this alliance is dominated by a typically short (3-5 m tall), open to moderately dense (10-60% cover) broad-leaved evergreen tree canopy. A sparse to moderately dense shrub layer may be present that is dominated by evergreen shrubs and rosettes succulents such as Agave spp. The graminoid layer is sparse to moderately dense and dominated by medium-tall, warm-season perennial bunch grasses. The forb layer is generally sparse but may have high species diversity. Cacti are commonly present.
Floristics: The vegetation is characterized by an open to moderately dense (10-60% cover), broad-leaved evergreen tree layer (encinal) dominated by Quercus oblongifolia. The oak-dominated tree canopy is typically 3-5 m tall, but may extend beyond 5 m. Juniperus deppeana, Quercus arizonica, Quercus emoryi, Prosopis spp., and occasional Pinus discolor may be present in the tree canopy (Stuever and Hayden 1997a). Shrubs may be scattered or form open to moderately dense layers. Associated shrubs and succulents include Acacia constricta, Agave palmeri, Arctostaphylos pungens, Brickellia spp., Dasylirion wheeleri, Ericameria laricifolia, Eriogonum wrightii, Eysenhardtia orthocarpa, Garrya wrightii, Mimosa aculeaticarpa var. biuncifera, Mimosa dysocarpa, Nolina microcarpa, Opuntia phaeacantha, Cylindropuntia spinosior (= Opuntia spinosior), Rhus trilobata, and Yucca madrensis (= Yucca schottii) (Stuever and Hayden 1997a). The graminoid layer is typically moderate to dense (5-80% cover) and is typically dominated by medium-tall bunchgrasses such as Bouteloua curtipendula, Schizachyrium cirratum (= Andropogon cirratus), or Muhlenbergia emersleyi, but it can also be very diverse (Stuever and Hayden 1997a). Other common graminoids may include Aristida ternipes, Bothriochloa barbinodis, Bouteloua chondrosioides, Bouteloua eriopoda, Bouteloua gracilis, Bouteloua hirsuta, Eragrostis intermedia, Leptochloa dubia, Muhlenbergia longiligula, and Piptochaetium fimbriatum. The usually sparse, but often diverse, forb layer is composed of Artemisia ludoviciana, Chenopodium spp., Commelina spp., Evolvulus spp., Hybanthus attenuatus, Ipomoea cristulata, Mirabilis longiflora, Viguiera spp., and many others (Stuever and Hayden 1997a). Diagnostic of this association is the dominance of Quercus oblongifolia in the tall-shrub canopy with at least 5% cover and a grassy understory.
Dynamics: Over the last century, the woody component in this alliance has increased in density over time in the absence of disturbance such as fire (Burgess 1995, Gori and Enquist 2003, Turner et al. 2003c, Schussman 2006a). This is correlated to a decrease in fire frequency that is related to a reduction of fine fuels that carry fire because of extensive livestock grazing. Frequent, stand-replacing fire was likely a key ecological attribute prior to 1890 (Wright 1980, Bahre 1985, McPherson 1995, Kaib et al. 1996). Quercus oblongifolia sprouts abundantly after being stem-killed by fire (Niering and Lowe 1984). Many of the understory species are reduced, especially the succulent plants such as Agave, Dasylirion and Nolina. More study is needed to understand the effects of altered fire regimes on the vegetation.
Environmental Description: This scrub woodland alliance is found in southeastern Arizona and northern Mexico. Stands occur on gently to moderately sloping alluvial plains and bajadas to steep rocky slopes in canyons, foothills and mountains. Elevation ranges from 1150 -1700 m. Climate is semi-arid with hot summers and moderate winters. Mean annual precipitation is approximately 45 cm, but varies with elevation. Approximately one-half of the annual precipitation occurs in late winter and the other half between July and September, often as high-intensity convective storms. May through June are typically dry with no significant precipitation. Stands occur on gently to moderately sloping alluvial plains and bajadas to moderate and steep rocky slopes in canyons, foothills and mountains. At lower elevations stands are restricted to the more mesic north aspects (Cumming 1951). Soils are gravelly or stony sandy loams or sandy clay loams, derived from a mixture of alluvium and colluvium. Parent materials include rhyolites, tuffs, andesites, felsites and agglomerates. Adjacent vegetation above these stand is often woodlands or forests dominated by Pinus ponderosa, Pinus leiophylla, Pinus edulis, and Juniperus deppeana. At lower elevations, shrub savannas dominated by some of the same species are likely.
Geographic Range: Scrub woodlands included in this alliance occur in mountains in southeastern Arizona and may also be found in the Mexican states of Chihuahua and Sonora.
Nations: MX,US
States/Provinces: AZ, MXCHH, MXSON
Plot Analysis Summary:
http://vegbank.org/natureserve/ELEMENT_GLOBAL.2.899018
Confidence Level: Low
Confidence Level Comments: No Data Available
Grank: GNR
Greasons: No Data Available
| Type | Name | Database Code | Classification Code |
|---|---|---|---|
| Class | 1 Forest & Woodland Class | C01 | 1 |
| Subclass | 1.B Temperate & Boreal Forest & Woodland Subclass | S15 | 1.B |
| Formation | 1.B.1 Warm Temperate Forest & Woodland Formation | F018 | 1.B.1 |
| Division | 1.B.1.Nd Madrean-Balconian Forest & Woodland Division | D060 | 1.B.1.Nd |
| Macrogroup | 1.B.1.Nd.1 Alligator Juniper - Mexican Pinyon - Arizona White Oak Madrean Lowland Evergreen Woodland Macrogroup | M010 | 1.B.1.Nd.1 |
| Group | 1.B.1.Nd.1.a Arizona White Oak - Emory Oak - Mexican Blue Oak Woodland Group | G201 | 1.B.1.Nd.1.a |
| Alliance | A0791 Mexican Blue Oak Scrub Woodland Alliance | A0791 | 1.B.1.Nd.1.a |
| Association | CEGL000973 Mexican Blue Oak / Sideoats Grama Scrub | CEGL000973 | 1.B.1.Nd.1.a |
| Association | CEGL000974 Mexican Blue Oak / Common Sotol Scrub | CEGL000974 | 1.B.1.Nd.1.a |
Concept Lineage: Re-classified III.A.2.N.c. Quercus oblongifolia Shrubland Alliance (A.791) to shrubland as it better represent the data.
Predecessors: No Data Available
Obsolete Names: No Data Available
Obsolete Parents: No Data Available
Synonomy: > Quercus oblongifolia/Dasylirion wheeleri Habitat Type (Bassett et al. 1987) [relationship uncertain]
> Quercus oblongifolia/mixed Bouteloua Habitat Type (Bassett et al. 1987) [relationship uncertain]
> Quercus oblongifolia/mixed Bouteloua Habitat Type (Bassett et al. 1987) [relationship uncertain]
- Bahre, C. J. 1985. Wildfire in southeastern Arizona between 1859 and 1890. Desert Plants 7:190-194.
- Bassett, D., M. Larson, and W. Moir. 1987. Forest and woodland habitat types of Arizona south of the Mogollon Rim and southwestern New Mexico. Edition 2. USDA Forest Service, Southwestern Region, Albuquerque, NM.
- Bourgeron, P. S., and L. D. Engelking, editors. 1994. A preliminary vegetation classification of the western United States. Unpublished report. The Nature Conservancy, Western Heritage Task Force, Boulder, CO. 175 pp. plus appendix.
- Brown, D. E., C. H. Lowe, and C. P. Pase. 1979. A digitized classification system for the biotic communities of North America with community (series) and association examples for the Southwest. Journal of the Arizona-Nevada Academy of Science 14:1-16.
- Burgess, T. L. 1995. Desert grassland, mixed shrub savanna, shrub steppe, or semidesert scrub. Pages 31-67 in: M. P. McClaran and T. R. Van Devender, editors. The Desert Grassland. University of Arizona Press, Tucson.
- Cumming, K. J. 1951. The effect of slope and exposure on range vegetation in desert grassland and oak woodland areas of Santa Cruz County, Arizona. Unpublished thesis, University of Arizona, Tucson. 53 pp.
- Faber-Langendoen, D., J. Drake, M. Hall, G. Kittel, S. Menard, C. Nordman, M. Pyne, M. Reid, M. Russo, K. Schulz, L. Sneddon, K. Snow, and J. Teague. 2013-2019b. Screening alliances for induction into the U.S. National Vegetation Classification: Part 1 - Alliance concept review. NatureServe, Arlington, VA.
- Gori, D. F., and C. A. F. Enquist. 2003. An assessment of the spatial extent and condition of grasslands in central and southern Arizona, southwestern New Mexico and northern Mexico. The Nature Conservancy, Arizona Chapter, Phoenix. 29 pp.
- Kaib, M., C. Baisan, H. D. Grissino-Mayer, and T. W. Swetnam. 1996. Fire history of the gallery pine-oak forests and adjacent grasslands of the Chiricahua Mountains of Arizona. Pages 253-264 in: P. F. Ffolliott, L. F. DeBano, M. B. Baker, G. J. Gottfried, G. Solis-Garza, C. B. Edminster, D. G. Neary, L. S. Allen, and R. H. Hamre, editors. Effects of fire on Madrean Province ecosystems: A symposium. Proceedings; 1996 March 11-15; Tucson, AZ. General Technical Report RM-289. USDA Forest Service, Rocky Mountain Forest and Experiment Station, Fort Collins, CO. 277 pp.
- Kearney, T. H., and R. H. Peebles, and collaborators. 1969. Arizona flora. University of California, Berkeley, CA. 1085 pp.
- Kincaid, D. R. 1959. The upper desert grassland of southern Arizona: A basic ecological analysis. Unpublished thesis, University of Arizona, Tucson. 38 pp.
- Larson, M., and W. H. Moir. 1987. Forest and woodland habitat types of northern New Mexico and northern Arizona. Edition 2. USDA Forest Service, Southwestern Region, Albuquerque, NM.
- McPherson, G. R. 1995. The role of fire in the desert grasslands. Pages 130-151 in: M. P. McClaran and T. R. Van Devender, editors. The Desert Grassland. University of Arizona Press, Tucson.
- Niering, W. A., and C. H. Lowe. 1984. Vegetation of the Santa Catalina Mountains: Community types and dynamics. Vegetatio 58:3-28.
- Schussman, H. 2006a. Historical range of variation and state and transition modeling of historical and current landscape conditions for semi-desert grassland of the southwestern U.S. Prepared for the USDA Forest Service, Southwestern Region by The Nature Conservancy, Tucson, AZ. 53 pp.
- Schussman, H. 2006b. Historical range of variation for Madrean encinal of the southwestern U.S. Prepared for the USDA Forest Service, Southwestern Region by The Nature Conservancy, Tucson, AZ. 16 pp.
- Stuever, M. C., and J. S. Hayden. 1997b. Plant associations of Arizona and New Mexico. Volume 2: Woodlands. USDA Forest Service, Southwestern Region, Habitat Typing Guides. 196 pp.
- Turner, R. M., R. H. Webb, J. E. Bowers, and J. R Hastings. 2003. The changing mile revisited: An ecological study of vegetation change with time in the lower mile of an arid and semiarid region. University of Arizona Press, Tucson.
- Wright, H. A. 1980. The role and use of fire in the semi-desert grass-shrub type. General Technical Report INT-85. USDA Forest Service, Intermountain Forest and Range Experiment Station, Ogden, UT. 23 pp.