Tamarix

The genus Tamarix (tamarisk, salt cedar) is composed of about 50-60 species of flowering plants in the family Tamaricaceae, native to drier areas of Eurasia and Africa.^[2] The generic name originated in Latin and may have referred to the Tamaris River in Hispania Tarraconensis (Spain).^[3]

Contents 1 Description 2 Reproduction 3 Selected species 3.1 Formerly placed here 4 Tamarix in North America 4.1 Invasive species 4.1.1 Controls 5 Uses 5.1 Invasive species 6 Cultural history 7 References 7.1 Further reading 8 External links

Description

They are evergreen or deciduous shrubs or trees growing to 1–18 m in height and forming dense thickets. The largest, Tamarix aphylla, is an evergreen tree that can grow to 18 m tall. They usually grow on saline soils, tolerating up to 15,000 ppm soluble salt and can also tolerate alkali conditions.

Tamarisks are characterized by slender branches and grey-green foliage. The bark of young branches is smooth and reddish-brown. As the plants age, the bark becomes bluish-purple, ridged and furrowed. The leaves are scale-like, 1–2 mm long, and overlap each other along the stem. They are often encrusted with salt secretions. The pink to white flowers appear in dense masses on 5–10 cm long spikes at branch tips from March to September, though some species (e.g. T. aphylla) tend to flower during the winter.

Reproduction

Tamarix can spread both vegetatively, by adventitious roots or submerged stems, and sexually, by seeds. Each flower can produce thousands of tiny (1 mm diameter) seeds that are contained in a small capsule usually adorned with a tuft of hair that aids in wind dispersal. Seeds can also be dispersed by water. Seedlings require extended periods of soil saturation for establishment.

Tamarix species are fire-adapted, and have long tap roots that allow them to intercept deep water tables and exploit natural water resources. They are able to limit competition from other plants by taking up salt from deep ground water, accumulating it in their foliage, and from there depositing it in the surface soil where it builds up concentrations temporarily detrimental to some plants. The salt is washed away during heavy rains. Tamarix trees are most often propagated by cuttings.

Tamarix species are used as food plants by the larvae of some Lepidoptera species including Coleophora asthenella which feeds exclusively on T. africana.

Selected species

Tamarix africana Poir. Tamarix androssowii Tamarix aphylla (L.) H.Karst. Tamarix arceuthoides Tamarix austromongolica       Tamarix boveana Tamarix canariensis Tamarix chinensis Lour. Tamarix dalmatica Tamarix dioica Roxb. ex Roth Tamarix duezenlii Tamarix elongata Tamarix gallica L. Tamarix gansuensis Tamarix gracilis Willd. Tamarix hampeana Tamarix hispida Willd.      Tamarix indica Tamarix jintaenia Tamarix juniperina Tamarix karelinii Bunge Tamarix laxa Willd. Tamarix leptostachys Tamarix mongolica Tamarix parviflora DC. Tamarix ramosissima Ledeb. Tamarix sachuensis Tamarix smyrnensis Bunge (=T. hohenackeri) Tamarix taklamakanensis Tamarix tarimensis Tamarix tenuissima Tamarix tetragyna Ehrenb. Tamarix tetragyna var. meyeri (Boiss.) Boiss. (=T. meyeri) Tamarix tetragyna var. tetragyna Tamarix tetrandra Pall. ex M.Bieb.[4]

Formerly placed here

• Myricaria germanica (L.) Desv. (as T. germanica L.)^[4]

Tamarix in North America

The Tamarix was introduced to the United States as an ornamental shrub, a windbreak, and a shade tree in the early 19th century. In the 1930s, during the Great Depression, tree-planting was used as a tool to fight soil erosion on the Great Plains, and the trees were planted by the millions in the Great Plains Shelterbelt.^[5][6]

Eight species are found in North America. They can be divided into two sub-groups:

Evergreen species

The Tamarix aphylla (Athel tree), a large evergreen tree, does not sexually reproduce in the local climate and is not considered a seriously invasive species. The Athel tree is commonly used for windbreaks on the edge of agricultural fields and as a shade tree in the deserts of the Southwestern United States.

Deciduous species

• The second sub-group contains the deciduous tamarisks, which are small shrubby trees, commonly known as "saltcedars." These include Tamarix pentandra, Tamarix tetranda, Tamarix gallica, Tamarix chinensis, Tamarix ramosissima, and Tamarix parvifolia.^[7]

These deciduous trees establish themselves in disturbed and undisturbed streams, waterways, bottom lands, banks and drainage washes of natural or artificial water bodies, moist rangelands and pastures, and other areas where seedlings can be exposed to extended periods of saturated soil for establishment.

Invasive species

It is commonly believed that Tamarix disrupts the structure and stability of North American native plant communities and degrades native wildlife habitat, by outcompeting and replacing native plant species, salinizing soils, monopolizing limited sources of moisture, and increasing the frequency, intensity and effect of fires and floods. While it has been shown that individual plants may not consume larger quantities of water than native species,^[8] it has also been shown that large dense stands of Tamarix do consume more water than equivalent stands of native cottonwoods.^[9] There is an active and ongoing debate as to when Tamarix can out-compete native plants, and if it is actively displacing native plants or it just taking advantage of disturbance by removal of natives by humans and changes in flood regimes.^[10] Research on competition between Tamarix seedlings and co-occurring native trees has found that the seedlings are not competitive over a range of environments,^[11] however stands of mature trees effectively prevent native species establishment in the understory, due to low light, elevated salinity, and possibly changes to the soil biota.^[12] Thus, anthropogenic activities that preferentially favor tamarisk (such as changes to flooding regimes) are associated with infestation.^[13] To date, Tamarix has taken over large sections of riparian ecosystems in the western United States that were once home to native cottonwoods and willows,^[14] and are projected by some to spread well beyond the current range.^[15]

Controls

There are several ways to deal with pest populations of tamarisk in the United States. The National Park Service has used physically removing the plants, spraying them with herbicides, and introducing northern tamarisk beetles (Diorhabda carinulata) in the National Park System. This has been done in the Dinosaur National Monument in Utah and Colorado along the Green and Yampa Rivers, during the summers of 2006 and 2007.^[16] After years of study, the USDA Agricultural Research Service has found that the tamarisk beetles eat only the tamarisk, and starve when there is no more tamarisk available. No other native North American plants have been found to be eaten by the introduced tamarisk beetle. Progress is slow, but proves that containment of the tamarisk is possible in the long term.^[17]

Uses

• The tamarisk is used as an ornamental shrub, a windbreak, and a shade tree. The wood may be used for carpentry or firewood. It is a possible agroforestry species.^{[16] [18]}
• Plans are being made for the tamarisk to play a role in anti-desertification programs in China.,^[19][20]
• Salt cedars can be planted to mine salts, then be used in the production of fuel and fertilizer (although the latter will be somewhat salty).^[21]

Invasive species

Tamarix ramosissima has naturalized and become a major invasive plant species in parts of the world, such as in the Southwestern United States and Desert Region of California, consuming large amounts of groundwater in riparian and oases habitats. The balance and strength of the native flora and fauna is being helped by various restoration projects, by removing, like tall woody noxious weeds, Tamarix groves.^[22]

Cultural history

In Genesis 21:33, Abraham is recorded to have "planted a tamarisk at Beer-sheba".^[23] He had built a well there, earlier.

In the Quran 34:16, the people of Saba were punished when "[Allah] converted their two garden (rows) into gardens producing bitter fruit and tamarisks [...]"

In Egyptian Mythology, the body of Osiris is hidden for a time in a tamarisk tree in Byblos, until it was retrieved by Isis. A reference to this is also made in the computer game, Age of Mythology, where the head of Osiris is said to be hidden inside the trunk of a great tamarisk tree.

Wedgwood made a “Tamarisk” China pattern.

According to the New Larousse Encyclopedia of Mythology, the tamarisk plant is a favorite of the Greek god Apollo.

References

Further reading

• Anderson, B. W. (1996), "Salt cedar, revegetation and riparian ecosystems in the Southwest.", Proceedings of the California Exotic Pest Plant Council, Symposium '95. California Exotic Pest Plant Council, Pacific Grove, California.: 32–41 .
• Anderson, B. W. (1998), "The case for salt cedar.", Restoration and Management Notes 16: 130–134, 138 .
• Cooper, D.; Merritt, David M.; Andersen, Douglas C.; Chimner, Rodney A. (1999), "Factors Controlling the Establishment of Fremont Cottonwood Seedlings on the Upper Green River, USA", Regul. Rivers: Res. Mgmt. 15 (5): 419–440, doi:10.1002/(SICI)1099-1646(199909/10)15:5<419::AID-RRR555>3.0.CO;2-Y .
• Cooper, D.; Andersen, Douglas C.; Chimner, Rodney A. (2003), "Multiple pathways for woody plant establishment on floodplains at local to regional scales", Journal of Ecology 91 (2): 182–196, doi:10.1046/j.1365-2745.2003.00766.x .
• Christensen, E. M. (1962), "The Rate of Naturalization of Tamarix in Utah", American Midland Naturalist (American Midland Naturalist, Vol. 68, No. 1) 68 (1): 51–57, doi:10.2307/2422635, JSTOR 2422635 .
• Everitt, B. L. (1980), "Ecology of Saltcedar - A plea for research", Environmental Geology 3 (3): 77–84, doi:10.1007/BF02473474 .
• Everitt, B. L. (1998), "Chronology of the spread of Tamarisk in the central Rio Grande", Wetlands (18): 658–668 .
• Stromberg, J. C. (1998), "Dynamics of Fremont cottonwood (Populus fremontii) and saltcedar (Tamarix chinesis) populations along the San Pedro River, Arizona", Journal of Arid Environments 40 (40): 133–155, doi:10.1006/jare.1998.0438 .
• Stromberg, J. C. (1998), "Functional equivalency of saltcedar (Tamarix chinensis) and Fremont cottonwood (Populus fremontii) along a free-flowing river", Wetlands (18): 675–686 .
• Zamora-Arroyo, F. (2001), "Regeneration of native trees in response to flood releases from the United States into the delta of the Colorado River, Mexico", Journal of Arid Environments 49 (49): 49–64, doi:10.1006/jare.2001.0835 .
• Zavaleta, E. (2001), "The Economic Value of Controlling an Invasive Shrub", Ambio 29 (8): 462–467 .
• Gilbert, Anna A.; Marshall, Diane L.; Gilbert, Steven A. (2000), "Competition between native Populus deltoides and invasive Tamarix ramosissima and the implications of reestablishing flooding disturbance", Conservation Biology 14 (6): 1744–1754, doi:10.1046/j.1523-1739.2000.99306.x .
• Sher (2002), "Spatial partitioning within southwestern floodplains: patterns of establishment of native Populus and Salix in the presence of invasive, non-native Tamarix", Ecological Applications 12: 760–772 .
• Sher, A. A.; Marshall, D. L. (2003), "Competition between native and exotic floodplain tree species across water regimes and soil textures", American Journal of Botany 90 (3): 413–422, doi:10.3732/ajb.90.3.413 .
• Bush; Smith, Stanley D (1995), "Mechanisms associated with decline of woody species in riparian ecosystems of the southwestern U.S", Ecological Monographs (Ecological Monographs, Vol. 65, No. 3) 65 (3): 347–370, doi:10.2307/2937064, JSTOR 2937064 .
• Taylor (1998), "Restoration of saltcedar (Tamarix sp.)-infested floodplains on the Bosque del Apache National Wildlife Refuge", Weed Technology 12: 345–352 .
• Shafroth (2000), "Woody riparian vegetation response to different alluvial water table regimes", Western North American Naturalist 60: 66–76 .
• Merritt, David M.; Cooper, David J. (2000), "Riparian vegetation and channel change in response to river regulation: A comparative study of regulated and unregulated streams in the Green River Basin, USA", Regulated Rivers: Research and Management 16 (6): 543–564, doi:10.1002/1099-1646(200011/12)16:6<543::AID-RRR590>3.0.CO;2-N .
• Horton, J. L.; Kolb, T. E.; Hart, S. C. (2001), "Responses of riparian trees to interannual variation in ground water depth in a semi-arid river basin", Plant, Cell and Environment 24 (3): 293–304, doi:10.1046/j.1365-3040.2001.00681.x .

External links

• Species Profile- Saltcedar (Tamarix spp.), National Invasive Species Information Center, United States National Agricultural Library. Lists general information and resources for Saltcedar.
• Flora Europaea Tamarix
• Flora of China Tamarix species list
• U.S. NPS guide
• Tamarix (Genus) zipcodezoo.com
• Exotic Tamarisk on the Colorado Plateau
• Tamarix, a natural resource on which the communities depend for fuelwood, tools, and basket making.
• Afforestation and Salinity Control Using Tamarix; in Western China
• Introduction of the Tamarisk Beetle in Dinosaur National Monument
• Saltcedar - Center for Invasive Species