Very high water use and increased deposition of salts on soil surface. The longer the community has been invaded by saltcedar the more xeric in nature are the plant species which occupy the understory. Such deposits of salt-encrusted needles can inhibit other species germination. Saltcedar has been blamed for increasing flooding by forming a partial barrier to floodflow, which can cause floodwater to disperse and inundate areas that otherwise would not be flooded. With the invasion of saltcedar there has been an apparent increase in the frequency of fire in riparian ecosystems. Evapotranspiration rates of saltcedar are among the highest of any phreatophyte evaluated in southwestern North America, including native riparian trees. Saltcedar has been reported to contain 41,000 ppm dissolved solids in the guttation sap.

The majority of birds do not use saltcedar in high proportions compared with native plant communities. Frugivores and insectivores, abundant in native riparian vegetation, almost completely avoid saltcedar. Studies showed that several species had a higher affinity for the cottonwood-willow association, including common flicker, yellow-bellied sapsucker, porcupine and beaver. With the exception of desert woodrat and desert cottontail, no native mammal species are known to feed upon saltcedar. Then consumed by wildlife, only young growth is utilized. Although certain wildlife species may find saltcedar beneficial to their survival, the encroachment of saltcedar has most certainly altered the native habitat that was apparently of great benefit to wildlife. Although the southwestern willow flycatcher can nest in saltcedar, infestation have a negative impact on most other birds that would normally use the native vegetation.

The development of water management programs that severely impact natural river flows has greatly contributed to spread of saltcedar. These alterations include reservoir and dam construction, river diversions, flow regulations, and irrigation projects. Historically, the flow of these rivers peaked in the late spring and early summer from snowmelt. These changes in channel geometry and streamflow created conditions unfavorable for the regeneration and survival of native riparian species. As a result, rapid colonization and expansion of saltcedar occurred throughout the western river systems. In addition to altering streamflow, clearing and plowing of floodplains and associated agricultural activity also aided saltcedar colonization during the 1800s. Saltcedar has also been reported to rapidly infest riparian areas exposed to heavy grazing. Once established, seed dispersal and plant fragments can become established in otherwise undisturbed areas. Establishment can occur on disturbed and undisturbed sites, but disturbance can increase the rate of establishment.

Recent trend in increase of saltcedar is about at a rate of 3 to 4% per year. Much of the riparian area in the southwestern US has been occupied by saltcedar and the rate of increase there has slowed down. However, the rate of increase in other areas where it is just becoming established, particularly in more northern regions is probably greater.

Brotherson, J.D. and D. Field. 1987. Tamarix: impacts of a successful weed. Rangelands 9:110-112; see DiTomaso, J.M. 1998. Impact, biology, and ecology of saltcedar (Tamarix spp.) in the southwestern United States. Weed Technology 12:236-336 for review and peer-reviewed reference citations.

Planted as an ornamental, as a shade tree, and for erosion control. Not nearly as widely planted today as in the past. Can still be purchased via the internet. It was planted as an ornamental shrub or shade tree, or to create wind breaks, or to stabilize eroding stream banks. It did not escape cultivation until around the 1870s. In the early 1900s, farmers were using this plant for erosion control. It became clear by the 1920s that saltcedar was becoming a serious problem.

Today, saltcedar infestations are common in most river systems over much of Utah, Nevada, Arizona, New Mexico, Colorado, Oklahoma, and Texas. Saltcedar is continuing to spread northward into Montana and Canada and southward into northwestern Mexico. Populations have been reported from as high as 2,135 m in the southern Rocky Mountains, but typically occur below 500 m. Seems to be weedy in areas similar to those in the southwestern US.

Tamarisk was first brought to North America in the 1800s, from southern Europe or the eastern Mediterranean region. Although saltcedar is typically found around aquatic or riparian areas, it has also been observed in scrublands, although not in dense stands.

Neill, W.M. 1985. Tamarisk. Fremontia 12:22-23; See both Lovich, J. Tamarix ramosissima. In, Invasive Plants of Californias Wildlands. Eds., C. Bossard, J. Randall, and M. Hoshovsky. UC Press, Berkeley and DiTomaso, J.M. 1998. Impact, biology, and ecology of saltcedar (Tamarix spp.) in the southwestern United States. Weed Technology 12:236-336 for review and other citations.