Saltcedar: A Non-Native Invasive Plant in the Western U.S

What effect does it have on natural habitat in the U.S.?

Effects on native vegetation. The most common native plants displaced by a saltcedar invasion are cottonwoods, mesquites, and willows growing along rivers and streams. The invasion of saltcedar is undoubtedly facilitated by human degradation of natural areas, such as areas where mesquite or cottonwood were over-harvested for firewood. Excessive groundwater pumping, dam building and flood control have also contributed to saltcedar establishment. Once saltcedar has invaded an area, it prevents native grasses, forbs and shrubs from recovering by exuding salts from its leaves, which increases the salinity of the surrounding soil beyond the tolerance of natives. Wildfires become more frequent and of higher intensity in saltcedar thickets, but saltcedar usually survives and regrows faster than natives.

Effects on native wildlife. In the U.S., saltcedar is not commonly eaten by native herbivores, such as bighorn sheep or deer. Furthermore, saltcedar seed are too small to be a food source for birds or rodents. Some bird species, including the endangered Southwestern Willow Flycatcher, will nest or seek cover in saltcedar, but this plant is not a better home than the displaced native willow. The European honeybee will collect pollen and nectar from saltcedar, but the honey is reported to be of inferior quality.

T. ramosissima (saltcedar) in a creek bed

The invasion of a desert spring by saltcedar can negatively affect native wildlife. Bighorn sheep and deer avoid drinking from water holes where visibility is limited. A saltcedar thicket not only obstructs their view, but can provide cover for predators, such as mountain lions, and can physically impede their access to water. Equally important in the arid west, saltcedar uses large amounts of water and can dry up or lower the quality of a water source, which impacts aquatic organisms such as frogs, fish, and salamanders. This is especially significant in drought years, which occur regularly.

T. parviflora (small flowered tamarisk) resprout from a stem fragment

Effects on the physical environment. Not only does saltcedar increase surface soil salinity and fire potential, but also thickets created by dense infestations along rivers or streams increase soil erosion caused by floods. This occurs when saltcedar thickets decrease channel width and force flood water beyond the stream bank. Some remarkable changes have been observed following removal of saltcedar from a densely infested area. At Eagle Borax Works Spring in Death Valley, California, a historic one-acre pond disappeared when it was invaded by saltcedar. Eight weeks after the saltcedar stand was removed with a controlled burn, the pond reappeared. Similarly, at Spring Lake near Artesia, New Mexico, a 13-acre lake returned after eradication of saltcedar, verifying the impact of saltcedar on groundwater resources.

T. parviflora (small flowered tamarisk) infestaton

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