Invalid Unit Specified
A0957 Juglans major - Juglans microcarpa Riparian Forest Alliance

The U.S. National
Vegetation Classification
Type Concept Sentence: This is a riparian wooded alliance where Juglans major or Juglans microcarpa dominates the upper canopy. Several other woody species, such as Acer negundo, Brickellia laciniata, Celtis laevigata var. reticulata, Chilopsis linearis, and Fallugia paradoxa, may be present. It occurs on perennial and intermittent streambanks and beds in the Southwest, typically gentle gradient but none-the-less very rocky reaches found in southern Arizona and New Mexico and it may also occur in adjacent areas in Mexico and southwestern Texas.
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Common (Translated Scientific) Name: Arizona Walnut - Little Walnut Riparian Forest Alliance
Colloquial Name: Arizona Walnut - Little Walnut Riparian Forest
Hierarchy Level: Alliance
Type Concept: This is a riparian wooded alliance where Juglans major or Juglans microcarpa dominates the upper canopy. Any of the following codominant trees or tall shrubs may also occur: Acer negundo, Brickellia laciniata, Pinus edulis, Platanus occidentalis, Platanus wrightii, Quercus spp., Salix gooddingii, or Sapindus saponaria. Other important shrubs and vines include Celtis laevigata var. reticulata, Fallugia paradoxa, Frangula californica, Rhus glabra, Rhus trilobata, Ungnadia speciosa, and Vitis arizonica. Common graminoid species are Bouteloua curtipendula, Bouteloua gracilis, and Carex spp. Forb cover has been reported to be sparse and typically weedy. This alliance occurs in and adjacent to streambeds in Arizona and New Mexico. It is typically found along rubble-bottomed perennial, intermittent and temporary streams, dry rocky ravines, arroyos, and streambeds from approximately 700-2300 m elevation.
Diagnostic Characteristics: No Data Available
Rationale for Nominal Species or Physiognomic Features:
Classification Comments: This alliance contains both short scrubby trees and taller forest-forming trees. Juglans major can have growth forms of tall shrubs or short trees.
Similar NVC Types:
Physiognomy and Structure: The woody canopy is dominated by broad-leaved deciduous tall shrubs or short trees, with an understory of shorter shrubs (1-2 m) and vines. A graminoid stratum is often present.
Floristics: This alliance is composed of structurally and compositionally variable riparian shrublands, with Juglans major or Juglans microcarpa being the most abundant and characteristic woody species. Other woody shrubs and small trees that can be present can include Acer negundo, Brickellia laciniata, Celtis laevigata var. reticulata, Chilopsis linearis, Fallugia paradoxa, Frangula californica (= Rhamnus californica), Fraxinus velutina, Ostrya knowltonii, Pinus edulis, Platanus occidentalis, Platanus wrightii, Quercus spp., Rhus glabra, Rhus trilobata, Salix gooddingii, Salix nigra, Sapindus saponaria, Ungnadia speciosa, and/or Vitis arizonica. The understory is composed primarily of perennial grasses such as Andropogon gerardii, Bouteloua curtipendula, Bouteloua gracilis, Carex spp., and Schizachyrium scoparium var. scoparium (= Schizachyrium scoparium ssp. neomexicanum). Forb cover was reported by Szaro (1989) to be sparse and typically weedy.
Dynamics: Juglans microcarpa is shade-intolerant. Young individuals direct much of their energy into developing a large, deep taproot, which permits saplings to survive the periods of extreme drought that are common.

Brown (1982a) states that the mixed broad-leaved types, of which Juglans major is included, are relictual communities. The present distribution reflects a contraction of the formerly widespread, Early Tertiary mixed mesophytic forest. These riparian forests are vernally adapted to Early Tertiary climates and have retreated to pockets where the warm temperate climate persists.
Environmental Description: It is found along perennial, intermittently and temporarily flooded streams. Sites include dry rocky ravines, arroyos, and streambeds from approximately 700 to 2300 m elevation. Stream gradients are to be 8-9 m per kilometer, fairly low gradients (Szaro 1989). The headwaters of these streams are in montane areas, and even when the streambed is dry, it is usually subirrigated by a shallow water table. Following monsoonal rains, the streambed can be shallowly inundated for several weeks at a time. Soils are fairly coarse and have been described as limestone cobbles, flat-bedded limestone streambeds, boulder, gravelly and "rubble-bottomed."
Geographic Range: Communities within this alliance occur throughout southern Arizona and the southwestern "boot heel" of New Mexico. Given the range of the nominal species, it is likely the alliance also occurs in Mexico (Elias 1987).
Nations: MX?, US
States/Provinces: AZ, MXSO?, NM
US Forest Service Ecoregions (1994/1995)
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Confidence Level: Low
Confidence Level Comments:
Grank: GNR
Name:Database Code:Classification Code:
Class 1 Forest & Woodland C01 1
Subclass 1.B Temperate & Boreal Forest & Woodland S15 1.B
Formation 1.B.3 Temperate Flooded & Swamp Forest F026 1.B.3
Division 1.B.3.Nd Western North American Interior Flooded Forest D013 1.B.3.Nd
Macrogroup M036 Interior Warm & Cool Desert Riparian Forest M036 1.B.3.Nd.2
Group G797 Western Interior Riparian Forest & Woodland G797 1.B.3.Nd.2.b
Alliance A0957 Arizona Walnut - Little Walnut Riparian Forest A0957
Association CEGL001103 CEGL001103
Association CEGL004594 CEGL004594
Association CEGL004593 CEGL004593
Association CEGL000858 CEGL000858
Association CEGL001102 Arizona Walnut Flooded Thicket CEGL001102
Association CEGL001101 CEGL001101
Association CEGL005954 CEGL005954
Association CEGL005955 CEGL005955
Association CEGL005957 CEGL005957
Association CEGL005956 CEGL005956
Association CEGL005326 CEGL005326
Concept Lineage: A.957 with minor name change.
Obsolete Names:
Juglans major - Juglans microcarpa Flooded Forest Alliance
Obsolete Parents:
Synonomy: ? Juglans microcarpa Community Type (Szaro 1989)
? Interior and Californian Riparian Deciduous Forests and Woodlands (Brown 1982a) [within Warm-Temperate Wetlands.]
? Little Walnut Series (Dick-Peddie 1993)
? Temperate Riparian Deciduous Forest Biome; Mixed Broadleaf Series (Pase and Layser 1977)
Concept Author(s): D. Culver, in Faber-Langendoen et al. (2013)
Author of Description: G. Kittel
Version Date: 18Dec2014
  • Brown, D. E., editor. 1982a. Biotic communities of the American Southwest-United States and Mexico. Desert Plants Special Issue 4(1-4):1-342.
  • Diamond, D. D. 1993. Classification of the plant communities of Texas (series level). Unpublished document. Texas Natural Heritage Program, Austin. 25 pp.
  • Dick-Peddie, W. A. 1993. New Mexico vegetation: Past, present, and future. University of New Mexico Press, Albuquerque. 244 pp.
  • Elias, T. S. 1987. The complete trees of North America: A field guide and natural history. Gramercy Publishing Company, New York. 948 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.
  • Freeman, C. E., and W. A. Dick-Peddie. 1970. Woody riparian vegetation in the Black and Sacramento Mountain ranges, southern New Mexico. The Southwestern Naturalist 15(2):145-164.
  • Henry, R. J. 1981. Riparian vegetation of two mountain ranges in southwestern New Mexico. Unpublished thesis, New Mexico State University, Las Cruces.
  • Kearney, T. H., and R. H. Peebles, and collaborators. 1969. Arizona flora. University of California, Berkeley, CA. 1085 pp.
  • Pase, C. P., and E. F. Layser. 1977. Classification of riparian habitat in the Southwest. Pages 5-9 in: Importance, preservation and management of riparian habitats: A symposium. General Technical Report RM-43. USDA Forest Service, Rocky Mountain Forest and Range Experiment Station, Fort Collins, CO.
  • Szaro, R. C. 1989. Riparian forest and scrubland community types of Arizona and New Mexico. Desert Plants Special Issue 9(3-4):70-139.