Print Report

A4026 Dicoria canescens - Abronia villosa - Panicum urvilleanum Dune Alliance

Type Concept Sentence: This alliance consists of sparsely vegetated (<10% cover) herbaceous stands where three or more of the following species can be found: Abronia villosa, Achnatherum hymenoides, Cleome sparsifolia, Croton californicus, Dicoria canescens, Geraea canescens, Oenothera deltoides, Panicum urvilleanum, Pleuraphis rigida, Rumex hymenosepalus, and Swallenia alexandrae. It occurs on dunes and sandsheets in the Mojave, Colorado, and Sonoran deserts of southwestern North America.

Common (Translated Scientific) Name: Desert Twinbugs - Desert Sand-verbena - Desert Panicgrass Dune Alliance

Colloquial Name: Mojave-Sonoran Sparsely Vegetated Dune

Hierarchy Level:  Alliance

Type Concept: This alliance consists of sparsely vegetated herbaceous stands with stoloniferous grasses and/or psammophitic herbs where generally three or more of the following species characterize an area: Abronia villosa, Achnatherum hymenoides, Cleome sparsifolia, Croton californicus, Dicoria canescens, Geraea canescens, Oenothera deltoides, Panicum urvilleanum, Pleuraphis rigida, Rumex hymenosepalus, and Swallenia alexandrae. Individual emergent shrubs such as Ambrosia dumosa, Atriplex canescens, Eriogonum deserticola, and Larrea tridentata may be present. Total plant cover rarely exceeds 10%. This alliance occurs in the Mojave, Colorado, and Sonoran deserts of southwestern North America. Habitats are dunes and sandsheets.

Diagnostic Characteristics: No Data Available

Rationale for Nominal Species or Physiognomic Features: No Data Available

Classification Comments: Name might need revision, and certainly characteristics of dunes in Mexico will need to be incorporated.

Similar NVC Types: No Data Available
note: No Data Available
Physiognomy and Structure: Vegetation included in this alliance has a sparse cover of xeromorphic shrubs and dwarf-shrubs less than 2 m tall. The herbaceous layer is typically sparse and is dominated by perennial graminoids, with ephemeral forbs and grasses present seasonally.

Floristics: This alliance consists of sparsely vegetated herbaceous stands with stoloniferous grasses and/or psammophitic herbs where generally three or more of the following species characterize an area: Abronia villosa, Achnatherum hymenoides (= Oryzopsis hymenoides), Cleome sparsifolia, Croton californicus, Dicoria canescens, Geraea canescens, Oenothera deltoides, Panicum urvilleanum, Pleuraphis rigida (= Hilaria rigida), Rumex hymenosepalus, and Swallenia alexandrae. Individual emergent shrubs such as Ambrosia dumosa, Atriplex canescens, Eriogonum deserticola, and Larrea tridentata may be present. Total plant cover rarely exceeds 10%.

Dynamics:  Constantly shifting sand limits the vegetative cover and species composition of this alliance. Active dune communities have a high number of endemic plants (Thorne 1982, Bowers 1984). These species'' adaptations to moving sand have resulted in the endemism (Bowers 1982). The active dune endemic Eriogonum deserticola avoids burial by drifting sand by rapid growth of shoots. Pleuraphis rigida is a common grass on sandy plains and dunes. Unlike most grasses, it has a woody structure and elevated renewal buds (Brown 1982a). Several years of above average annual precipitation can increase the cover of Pleuraphis rigida and other grasses to where stands resemble a desert grassland (Thorne 1982).
Environmental Description:  This alliance occurs on active and partially stabilized dune systems between 10 and 1200 m elevation. These dune systems move too rapidly to be stabilized by plants. Plant cover is therefore very sparse. Substrate is deep, shifting sand. Water is held for long periods of time just under the surface by sand, so shrubs that can survive long enough to get rooted can persist through long droughts. Climate is arid. Summer temperatures are hot, and winters only rarely dip below freezing. Precipitation has a bimodal distribution with almost half occurring from July to September and the rest occurring during the winter months.
Geographic Range: This alliance is found in Mojave, Colorado, and Sonoran deserts of southwestern North America.

Nations: MX,US

States/Provinces:  AZ, CA, MXBCN, MXSON, NV?


Confidence Level: Low

Confidence Level Comments: No Data Available
Grank: GNR

Greasons: No Data Available
Type Name Database Code Classification Code
Class 3 Desert & Semi-Desert Class C03 3
Subclass 3.A Warm Desert & Semi-Desert Woodland, Scrub & Grassland Subclass S06 3.A
Formation 3.A.2 Warm Desert & Semi-Desert Scrub & Grassland Formation F015 3.A.2
Division 3.A.2.Na North American Warm Desert Scrub & Grassland Division D039 3.A.2.Na
Macrogroup 3.A.2.Na.4 Saguaro - Organ Pipe Cactus - Burrobush Mojave-Sonoran Semi-Desert Scrub Macrogroup M088 3.A.2.Na.4
Group 3.A.2.Na.4.e North American Warm Semi-Desert Dune & Sand Flats Group G675 3.A.2.Na.4.e
Alliance A4026 Desert Twinbugs - Desert Sand-verbena - Desert Panicgrass Dune Alliance A4026 3.A.2.Na.4.e
Association CEGL001962 Colorado Desert Buckwheat Sand Dune Sparse Vegetation CEGL001962 3.A.2.Na.4.e
Association CEGL003001 Desert Sand-verbena Sparse Vegetation CEGL003001 3.A.2.Na.4.e
Association CEGL005468 Eureka Dunegrass Sparse Vegetation CEGL005468 3.A.2.Na.4.e
Association CEGL005747 Desert Twinbugs Dune Sparse Vegetation CEGL005747 3.A.2.Na.4.e
Concept Lineage: includes A.1852, A.1856

Predecessors: No Data Available

Obsolete Names: No Data Available

Obsolete Parents: No Data Available
Synonomy: > Dicoria canescens - Abronia villosa (Desert dunes) Alliance (Sawyer et al. 2009) [22.100.00]
> Dicoria canescens - Abronia villosa Sparsely Vegetated Alliance (Desert Dunes & Sand Flats) (Evens et al. 2012)
> Dicoria canescens-Abronia villosa Sparsely Vegetated Alliance (Evens et al. 2014)
> Panicum urvilleanum (Desert panic grass patches) Alliance (Sawyer et al. 2009) [42.095.00]
> Panicum urvilleanum Sparsely Vegetated Alliance (Evens et al. 2014)
> Swallenia alexandrae (Patches of Eureka Valley dune grass) Special Stands (Sawyer et al. 2009) [41.600.00]
> Swallenia alexandrae Sparsely Vegetated Alliance (Evens et al. 2014)
>< Active Desert Dunes (#22100) (Holland 1986b)
>< Desert Psammophytic Scrub (Desert Dune Sand Plant) (Thorne 1982)
>< Desert Sand-verbena Series (Sawyer and Keeler-Wolf 1995)
>< Stabilized and Partially Stabilized Desert Dunes (#22200) (Holland 1986b)
Concept Author(s): M.S. Reid, in Faber-Langendoen et al. (2013)

Author of Description: M.S. Reid

Acknowledgements: No Data Available

Version Date: 12-18-14
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  • Bowers, J. E. 1984. Plant geography of southwestern sand dunes. Desert Plants 6(1):31-42, 51-54.
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