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Taxonomic name: Tamarix ramosissima (Ledeb.) Synonyms: Tamarix pallasii var. brachystachys Bunge, Tamarix pentandra Common names: salt cedar (English), Sommertamariske (German), tamarisk (English), tamarix Organism type: tree, shrub Tamarix ramosissima is a deciduous shrub and can appear as a small tree that can grow in many different substrates. It can be found where its roots reach the water table, such as floodplains, along irrigation ditches and on lake shores and it can tolerate a wide range of saline or alkaline soils. This species can replace or displace native woody species. It is a poor quality food resource for aquatic consumers and the stems change the landscape properties of gravel and cobble islands and bars. T. ramosissima supports few native insects and thus is a poor habitat for birds. It is able to dominate floodplain communities in the deserts of the Southwest United States due to its ability to tolerate water stress for extended periods of time. An integrated management approach that incorporates multiple control techniques is required to manage this species. Description T. ramosissima is a semi-deciduous, loosely branched shrub or small to medium-sized tree. The branchlets are slender with minute, appressed scaly leaves. The leaves are rhombic to ovate, sharply pointed to gradually tapering, and 0.5 - 3.0mm long. The margins of the leaves are thin, dry and membranaceous. Flowers are whitish or pinkish and borne on slender racemes 2-5cm long on the current year's branches and are grouped together in terminal panicles. The pedicels are short. The flowers are most abundant between April and August, but may be found any time of the year. Petals are usually retained on the fruit. The seeds are borne in a lance-ovoid capsule 3-4mm long; the seeds are about 0.45mm long and 0.17mm wide and have unicellular hairs about 2mm long at the apical end. The seeds have no endosperm and weigh about 0.00001 gram. (Carpenter, 2003; Dudley, pers. comm.). Similar Species Tamarix aphylla, Tamarix canariensis, Tamarix chinensis, Tamarix gallica, Tamarix parviflora More Occurs in: agricultural areas, coastland, desert, estuarine habitats, lakes, riparian zones, ruderal/disturbed, urban areas, water courses, wetlands Habitat description Grows on many different substrates, from sea level to 2100m elevation, but prefers fine-textured soils. Has a wide tolerance of saline and alkaline soils. Successful establishment is correlated with alkaline soils, available soil moisture, and disturbance of native vegetation (Carpenter, 2003). The roots of T. ramossisima are able to reach deep water tables but periods without access to water are tolerated (Dudley, pers. comm.). T. ramossisima benefits from altered hydrology, especially where natural flooding is attenuated by water regulation. The largest infestations are typically downstream of dams where they benefit from reduced flooding and more stable hydrology (Shafroth et al. 2005, Robinson 1965, Everitt 1998), partly because tamarisk seedlings are less tolerant of flood scour than are native seedlings (D'Antonio et al. 1999). Juveniles are poor competitors with other riparian plants (Sher et al. 2000, 2002; Dudley et al. 2000), so their establishment is generally associated with conditions where substrates are bare, such as after flood scouring or on lake margins when lake levels subside (Dudley, pers. comm.). General impacts Alteration of natural flooding regimes through dam construction has resulted in T. ramossisima replacing many native tree species, such as cottonwood (Populus deltoides subsp. wislizenii) and willows (Salix spp.), in riparian forests (Everitt 1980; Horton 1977; Robinson 1965; Graf 1978). The invasion of T. ramossisima along streams is likely to have altered the food webs in these aquatic ecosystems (Kennedy & Hobbie 2004). The roots of T. ramossisima bind together gravel and cobble riverbeds, resulting in enlarged bars and narrowed channels (Cooper et. al 2003). The leaf litter and foliage produced by T. ramossisima is flammable and encourages the spread of wildfires (Busch 1995; Brotherson & Field 1987; Dudley et. al 2000). Native vegetation and wildlife is destroyed in these fires, while T. ramossisima seedlings are able to increase their spread. This is due to their ability to re-sprout more successfully than native plants following fire (Huntert et. al 1988; Busch 1995; Ellis 2001; Dudley et. al 2000). T. ramossisima is also known to transpire large amounts of groundwater, which dessicates soils and reduces the water table. Its transpiration rate is similar to native plants on a per-leaf basis but it maintains a larger leaf area per ground area, and therefore uses more water in total (Sala et. al 1996; Dahm et. al 2002; Shafroth et. al 2005; Cleverly et. al 2002). Because T. ramossisima can take up water from non-saturated soils, it has an added advantage in outcompeting native vegetaion (Dudley, pers. comm.). Uses Often planted as an ornamental and to prevent erosion in arid areas. T. ramossisima provides a nectar source for honeybees in some areas, and is widely used in the old world for furniture making and for firewood, for tannin extraction, and for cover for livestock (Dudley, pers. comm.). T. ramossisima may also be useful for bioremediation, for instance it takes up perchlorate from groundwater, perchlorate being a pollutant derived from jet fuel (Urbansky et al. 2000). Many species of native birds, including the endangered and federally protected south-western willow flycatcher (Empidonax traillii extimus), are able to exploit T. ramosissima for shelter and nesting, especially when some native trees remain (Fleishman et al. 2003). However, it is mostly foliage gleaners and fairly opportunistic species that use it to a substantial extent - cavity nesters like owls and wrens, drillers like woodpeckers and sapsuckers, frugivores, granivores and other specialists rarely occupy tamarisk (Ellis 1995, Shafroth et al. 2005, Hunter 1984, Hunter et al. 1985, Cohan et al. 1979, Lovich and DeGouvenain 1998, Dudley and DeLoach 2005) and usage by insectivores declines greatly as vegetation dominance by tamarisk increases (Yard et al. 2004). Notes There are few plants that are true genetic species of T. ramosissima in infested areas, at least in North America. Most of what is called T. ramosissima represents a variety of hybrids, including haplotypes of T. ramosissima, T. chinensis, T. gallica and others (Gaskin and Schaal 2002); it even hybridizes with athel (T. aphylla), an evergreen species, in some southwest U.S. locations (Gaskin and Shafroth, in press). Geographical range Native range: Southern Europe to Asia minor and eastward to Mongolia, Tibet, central China, and North Korea (Carpenter, 2003). Known introduced range: North America (USDA-NRCS, 2400). Introduction pathways to new locations For ornamental purposes: Introduced as ornamentals and for windbreaks (Sobhian et. al 1998). Landscape/fauna "improvement": Introduced as ornamentals and for windbreaks (Sobhian et. al 1998). Nursery trade: Introduced as ornamentals and for windbreaks (Sobhian et. al 1998). Local dispersal methods On animals (local): Massive quantities of minute seeds are readily dispersed by wind (Carpenter 2003). Management information Mechanical: Hand pulling can be used where plants are small, access is difficult, or herbicides cannot be used (Carpenter 2003). Bulldozing, followed by root-plowing is successful, consistent and effective when used on large thickets of established T. romassisima. The downside is that this method is also very expensive (Smith, 2005. pers. comm.) Chemical: Aerial application of the herbicide imazapyr, alone or in combination with glyphosate, is effective and practical for controlling T. ramosissima over thousands of hectares, particularly in dense stands where little on no native vegetation is present. Several field trials have produced control rates of > 90% after one or two years (Carpenter 2003). On smaller sites the cut stump method is succesful when triclopyr herbicides are also used. Basal bark applications of Garlon4 were very effective on plants with a basal diameter of less than 4 inches. Burning, followed by herbicide application to the resprouts, also produced excellent results, although this method is not appropriate when T. ramossisima exists as a component of native plant communities (Carpenter 2003). The use of triclopyr (Garlon4 or Remedy) mixed with oil and applied as a basal bark or cut stump treatment has been used with great success to eliminate scattered infestations, with no resprouting occurring. The basal bark treatment involves applying the herbicide mixture to the lower 18 inches of the plant clear to the ground. This method is very selective, as it kills only the target plant and not the surrounding vegetation. Although labour-intensive, this method requires little or no restoration work if the tamarisk can be controlled before it has become dominant (Baker, 2005. pers. comm.). Herbicides used at aquatic sites include Arsenal and Habitat. These are very effective as foliar treatments, but they are not selective and so must be used with care. Around 30% of tamarisk may resprout after three years when using these herbicides (Baker, 2005. pers. comm.). Biological: Cattle (and probably goats) will eat T. ramosissima, but grazing alone is probably not a feasible control method. However, goats might be able to control dense stands of T. ramosissima where little native vegetation is present, particularly if the stands are cut or burned first, with goats eating the regrowth (Carpenter 2003). A biocontrol agent, the saltcedar leaf beetle (Diorhabda elongata), has been released in nine states (California, Oregon, Nevada, Utah, Wyoming, Colorado, Montana, New Mexico and Texas), excluding those areas where the endangered southwestern willow flycatcher is nesting in tamarisk (Dudley et al. 2001, DeLoach et al. 2004). A request for implementation across 14 western states has been submitted to federal regulators, but this has not yet been approved (Richard 2003). It is anticipated that control by the leaf beetle will be gradual because three years of defoliation resulted in major dieback, but very little mortality of host plants (Dudley and DeLoach 2005). Several genetically distinct geographic biotypes of the beetle are being used because the latitudes of origin and introduction of the beetles must be matched due to its developmental requirements (Bean et al. 2001). A mealybug (Trabutina mannipara) and a weevil (Coniatus tamarisci) have also been approved, but not yet released pending results from beetle introductions, and several other specialist herbivores are being considered for biocontrol potential (DeLoach et al. 2004) Nutrition T. ramossisima is a facultative phreatophyte, meaning that its roots are able to reach deep water tables but it is capable of tolerating periods without access to water (Carpenter 2003). Reproduction T. ramosissima is highly fecund. It produces massive quantities of minute seeds that are readily dispersed by wind (Carpenter 2003) but are usually only viable for a few days (Dudley pers. comm.). T. ramosissima seeds have no dormancy or after-ripening requirements. Germination can occur almost immediately upon reaching a moist site, and germination conditions are broad, good germination being found from 10 to 35°C, but mid-summer seed collections indicated poorer germination rates than those collected in late spring (Young et al. 2004). T. ramosissima flowered in two flushes, one in April-May and another in late July in northern Arizona, presumably reflecting availability of spring snowmelt and summer monsoon moisture. This species flowered continuously under favourable environmental conditions but the flowers require insect pollination to set seed (Carpenter 2003). Lifecycle stages T. ramosissima will produce roots from buried or submerged stems or stem fragments. This allows the species to produce new plants vegetatively following floods from stems torn from the parent plants and buried by sediment. Ideal conditions for first-year survival are saturated soil during the first few weeks of life, a high water table, and open sunny ground with little competition from other plants. The seedlings of this species grow more slowly than many native riparian plant species and it is highly susceptible to shading (Carpenter, 2003). This species has been nominated as among 100 of the "World's Worst" invaders Reviewed by: Major update under progress Tom Dudley, Research Assistant Professor Dept. of Natural Resources and Environmental Sceinces , University of Nevada USA Principal sources: Carpenter, 2003 Element Stewardship Abstract for Tamarix ramosissima Ledebour Compiled by: National Biological Information Infrastructure (NBII) & IUCN/SSC Invasive Species Specialist Group (ISSG) To contribute information, please contact Shyama Pagad. Last Modified: Thursday, 31 May 2007