All about the Saltcedar or Tamarisk Trees
at Rasor Road and Rasor Ranch

Saltcedar is the common name for several introduced species of shrubs or small trees including Tamarix chinensis, T. parviflora, and T. ramosissima. Saltcedar invades riparian habitats and displaces native flora and fauna. Saltcedar was first introduced in the U.S. to reclaim eroded areas and prevent further loss of stream banks, primarily in the southwest. Saltcedar has been sold in the horticultural industry, primarily for its wide adaptability and pink flowers.

How do I identify this plant? Saltcedar, or tamarisk, is a shrubby bush or tree that can range in size from 5 to 20 feet tall (and taller). The bark is a reddish brown, especially on younger branches. The leaves are small and flat and resemble evergreen shrubs such as arborvitae (Figure 2). Flowers are pink to white in color, five-petaled, and appear from mid to late summer. The seeds are extremely tiny and similar in size and color to pepper. Each seed has a pappus which allows it to float long distances in water or move in the wind. Seeds are short-lived and usually germinate within a few months after dispersal.

What is saltcedar's growth cycle? Once saltcedar seeds germinate it can grow rapidly to a small flowering shrub in one to two years. The plant is very hardy and horticultural varieties are advertised to grow "in sun or shade, and in wet or dry areas. The plant quickly establishes a long, woody taproot to support a voracious thirst for water. The root system is capable of producing many new shoots if the top growth is removed by mechanical control methods or fire.

Why is this plant a concern? Saltcedar can quickly become a monoculture along lakes and waterways. A single plant has been reported to transpire over 200 gallons of water per day. In the early morning and evening moisture with high salt content is exuded from the foliage, causing the soil to become saline. Saltcedar can choke waterways and has even dried up entire lakes. Native riparian species are quickly displaced by saltcedar, which in turn causes displacement of native birds and animals that generally do not feed on the leaves or eat the saltcedar seeds. Saltcedar, even in the seedling stage, will tolerate short-term flooding and can establish away from waterways when seeds are washed in during flooding. Once established the plants can become so thick cattle will not graze the area. Almost nothing can grow under the Saltcedars and they are very hard to kill. The tree is excellent for shade. The trees will usually have a root system that is about a 10:1 ratio of its height meaning that if a tree is about 20 feet tall, the roots can go down into the ground over 100 feet to find water.

Tamarisk typically occupies sites with intermediate moisture, high water tables, and minimal erosion. Saltcedar mainly occurs along floodplains, riverbanks, stream courses, salt flats, marshes, and irrigation ditches in arid regions of the Southwest. It often forms pure stands in disturbed riparian areas of the Southwest. In the Great Plains, saltcedar is common along streams, in low undrained areas, and around lakeshores, especially in the Arkansas and Cimarron river valleys and is occasionally found on dry hillsides.

Its roots may penetrate soil 30-100 feet but it generally grows where the depth of the water table does not exceed 25 feet (7.6 m), and normally where it is less than 15 feet (4.6 m). Dense stands will grow only where the water table is between 5 and 20 feet (1.5-6 m) below the soil surface. If the water table is less than 5 feet (1.5 m) from the surface, the plants branch profusely and do not form a dense stand.

1940s. These three species of saltcedar had spread extensively along the Gila, Salt, Pecos, Colorado, and Rio Grande rivers. The construction of dams and flood control structures along these rivers altered natural flooding regimes and provided ideal conditions for the establishment, reproduction, and growth of saltcedar.

1960s. By 1961, at least 1,400 square miles of floodplain in the western United States were infested by saltcedar. Since the 1960s, 70% of the original native vegetation in Afton Canyon, California, has been replaced by saltcedar. Reduced river flows, off-road vehicles, year-round grazing, and native tree cutting may have permitted the establishment and spread of saltcedar in such areas.

1970s and 1980s. Saltcedar has moved into interior desert riparian habitats that are relatively undisturbed by human activities.

1998. Saltcedars have successfully invaded nearly every drainage system in arid and semi-arid areas in the southwestern United States and occupy over 1 million acres. Saltcedars now occupy most suitable habitat west of the Great Plains, north into Montana, and south into northwestern Mexico.

Reason Why it has Become Established:  Saltcedar, like many other invasive plant species, has a great reproductive capability. A mature saltcedar plant can produce 600,000 seeds annually, and has the ability to flower during its first year. Seeds are easily dispersed by wind and water, and severed stems and shoots of saltcedar readily root in moist soil. The plant's ability to exploit suitable germinating conditions over a long time period gives saltcedar a considerable advantage over native riparian species.
 

A very rapid grower, saltcedar can grow 9 to 12 feet in a single season under good conditions. Rapid growth can allow the invading plant to reproduce within the first year. In extreme environmental conditions such as drought or flooding, it is extremely resistant. Under drought, saltcedar survives by dropping its leaves and halting growth. Additionally, its seedlings are very resistant to desiccation. Under flooding, it can survive immersion for up to 70 days.

Mature plants can resprout vegetatively after fire, flood, or treatment with herbicides and can adapt to wide variations in soil and mineral gradients.

Saltcedar also deposits salt above and below the ground, forming a saline crust inhibiting other plants from growing in its vicinity. In addition to outcompeting native species, this also enables the saltcedar to cope with high concentrations of dissolved solids.

Burning of the Saltcedar Trees in Afton Canyon

The initial date for the prescribed management burn in Afton Canyon was November, 1991. This period was chosen because it was assumed that the saltcedar would be dormant, fuel moistures would be fairly low and temperatures/humidity would be moderate. As with many well laid plans, the saltcedar would not ignite. The winter rains began shortly thereafter, and the burn was on indefinite hold. On the last day of July, 1992 we tried again. The jackpots were lit and soon the saltcedar was an inferno! The high temperatures, light winds and low humidity provided ideal conditions for the prescribed burn. The flame lengths reached approximately 100 feet, threatening the native trees located within the fire breaks.

The fire was very effective. All that remained standing were larger blackened saltcedar stems and trunks. The smaller branches, duff, leaves and decadent limbs were all consumed. The fire visibly opened the burn area allowing the soil to be clearly seen between the blackened standing material. The fire encompassed approximately 80 percent of the proposed burn area. The areas where the fire didn't carry were usually in younger age stands and/or near the perimeter of the wet "green strip" where fewer combustible materials were available and moisture levels were higher.

The intensity of the fire was very high, killing the saltcedar outright in some areas and scorching many of the native trees that we had tried to protect. It was found that, to protect existing native trees, firebreaks must exceed 100 feet. Some of the above ground portions of the native trees survived and most that didn't resprouted basally. The resprouted willows are currently between ten and fifteen feet in height and growing. The results demonstrate that the initial contribution gained from the use of fire on saltcedar is that it opens the very dense stands to allow access for the spraying of resprouts.

The burned saltcedar began to basally resprout within a month following the burn. Different age classes and sizes of the burned saltcedar had different degrees of accessibility. The more tree like stands with larger, well spaced standing material were easier to access for herbicide application than the more closely spaced and younger age "thickets." Application of herbicide to the resprouts began approximately one month following the burn.

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