Physiognomy and Structure: No Data Available

Floristics: This introduced shrubland forms a moderate to dense tall-shrub layer that is solely or strongly dominated by species of Tamarix, including Tamarix ramosissima, Tamarix chinensis, Tamarix gallica, and Tamarix parviflora. Other native shrubs may include species of Salix (especially Salix exigua) and Prosopis, as well as Rhus trilobata and Sarcobatus vermiculatus but with low cover (if shrub species are codominant, then the stand is classified as a natural shrubland). Scattered native trees such as Acer negundo, Salix amygdaloides, Populus spp., or another introduced tree, Elaeagnus angustifolia, may also be present. Depending on stand age and density of the shrub layer, an herbaceous layer may be present. Associated native species include Distichlis spicata and Sporobolus airoides, and introduced species include Agrostis gigantea, Agrostis stolonifera, and Poa pratensis. Introduced herbaceous species such as Polypogon monspeliensis, Conyza canadensis, Lepidium latifolium, and many others have been reported from shrublands in this association.

Dynamics:  Tamarix species are highly competitive and have invaded many riparian and wetland environments in the western U.S. Hansen et al. (1995) report that these shrubs are extremely drought- and salt-tolerant, produce prolific wind-dispersed seeds, can resprout after burning or cutting, and if kept moist, buried or broken branches will develop adventitious roots and grow. Stands seem to favor disturbed and flow-regulated rivers, because the lack of annual overbank flooding and subsequent scouring allows seedlings to become established. However, Tamarix spp. will establish well in pristine areas, too, especially under drought conditions such as experienced by the Colorado Plateau in 2002-2003. Under optimum conditions riparian areas can be converted to a dense thicket in less than 10 years (Hansen et al. 1995). Once established, stands are extremely difficult to eradicate, requiring cutting along with herbicide application on stumps to prevent resprouting (Smith and Douglas 1989), as well as restoration of the original flooding and scouring regime. Many of the national parks in the western states have active programs of tamarisk removal and riparian restoration that have been moderately successful. A biocontrol agent, the northern tamarisk beetle (Diorhabda carinulata), has been used to defoliate tamarisk throughout the southwestern U.S. since 2001 and defoliation has been highly effective (Bateman et al. 2012).