1. Tamarix ramosissima on the Colorado River Should saltcedar be removed?

3. Remove saltcedar The review of the literature suggests that evapotranspiration (ET) of this saltcedar plant responsible for huge water loss. The review of the literature suggests that evapotranspiration (ET) of this saltcedar plant responsible for huge water loss. Some contend that if saltcedar was removed, enough water could be salvaged to supply major cities with enough water to meet municipal water demands. Some contend that if saltcedar was removed, enough water could be salvaged to supply major cities with enough water to meet municipal water demands. The replacement of native species by saltcedar is another issue of the Tamarix plant. The replacement of native species by saltcedar is another issue of the Tamarix plant.

4. Retain Tamarix Others state that ET loss is over exaggerated, and that the loss of native plants is due to the stress caused by the dams that have been placed on the rivers. Others state that ET loss is over exaggerated, and that the loss of native plants is due to the stress caused by the dams that have been placed on the rivers.

5. Despite decades of saltcedar invasion and control attempts, conflicting opinions remain about how, where, or if controlling saltcedar is likely to provide ecological or economic benefits that justify its removal. Despite decades of saltcedar invasion and control attempts, conflicting opinions remain about how, where, or if controlling saltcedar is likely to provide ecological or economic benefits that justify its removal.

6. Tamarisk possesses many classic weedy characteristics to which it owes its rapid spread and effective displacement of native vegetation. Tamarisk possesses many classic weedy characteristics to which it owes its rapid spread and effective displacement of native vegetation. It produces tremendous numbers of seeds which germinate quickly in a wide range of conditions, and the resulting plants can grow rapidly, up to 4 cm day It produces tremendous numbers of seeds which germinate quickly in a wide range of conditions, and the resulting plants can grow rapidly, up to 4 cm day In the process, tamarisk plants consume tremendous quantities of water and draw salts up to the surface from deep in the soil. In the process, tamarisk plants consume tremendous quantities of water and draw salts up to the surface from deep in the soil. These salts, secreted on the invader's leaves, give rise to increasingly saline soils not tolerated by native riparian species, such as Goodding willow (Salix gooddingii) and Fremont cottonwood (Populus fremontii) These salts, secreted on the invader's leaves, give rise to increasingly saline soils not tolerated by native riparian species, such as Goodding willow (Salix gooddingii) and Fremont cottonwood (Populus fremontii)

7. Tamarisk can tolerate both drought and flooding to degrees that native species cannot It can withstand submersion for up to 3 months, but it can also survive prolonged desiccation and is more able than native species to establish in areas with deep zones of permanent water availability. It can withstand submersion for up to 3 months, but it can also survive prolonged desiccation and is more able than native species to establish in areas with deep zones of permanent water availability. Fire may also be assisting the spread of tamarisk, both because the invader resprouts readily from belowground parts, and because the accumulation of its litter increases the probability of fire and salinizes the soil when fires do occur. Fire may also be assisting the spread of tamarisk, both because the invader resprouts readily from belowground parts, and because the accumulation of its litter increases the probability of fire and salinizes the soil when fires do occur. On average, after accounting for possible returns of transpired water to the region, tamarisk stands consume 3000 to 4600 m3 ha−1 yr−1 more water than the native vegetation that they replace. On average, after accounting for possible returns of transpired water to the region, tamarisk stands consume 3000 to 4600 m3 ha−1 yr−1 more water than the native vegetation that they replace.

8. Tamarisk – the water user It reaches deeper for groundwater farther from waterways, and it builds up banks and islands, which it then colonizes, through sediment capture It reaches deeper for groundwater farther from waterways, and it builds up banks and islands, which it then colonizes, through sediment capture Tamarisk invasion therefore represents not only a ha-per-ha replacement of less thirsty vegetation by a species that consumes more water; it also increases the extent of heavily vegetated (and therefore heavily transpiring) areas near waterways. Tamarisk invasion therefore represents not only a ha-per-ha replacement of less thirsty vegetation by a species that consumes more water; it also increases the extent of heavily vegetated (and therefore heavily transpiring) areas near waterways.

9. A second major impact of tamarix on the functioning of riparian ecosystems concerns flood control. When tamarix invades a riparian corridor, it establishes in dense and extensively rooted thickets. When tamarix invades a riparian corridor, it establishes in dense and extensively rooted thickets. These qualities—the same ones that make it a valuable tool for erosion control—also cause tamarisk to stabilize and trap sediment on sandbars, riverbanks, and midstream islands These qualities—the same ones that make it a valuable tool for erosion control—also cause tamarisk to stabilize and trap sediment on sandbars, riverbanks, and midstream islands Steady accretion enlarges banks and islands, narrowing river channels and reducing their waterholding capacity. Steady accretion enlarges banks and islands, narrowing river channels and reducing their waterholding capacity.

10. southern California's Metropolitan Water District (including Los Angeles) southern California's Metropolitan Water District (including Los Angeles) the four major cities of central Arizona (Phoenix, Tucson, Scottsdale, and Mesa) the four major cities of central Arizona (Phoenix, Tucson, Scottsdale, and Mesa) In each case, additional water generated by replacing tamarix with native vegetation would help to meet municipal water demands. In each case, additional water generated by replacing tamarix with native vegetation would help to meet municipal water demands. Two urban areas in the region affected by tamarisk are actively pursuing, at significant cost, schemes to augment their water supplies: Two urban areas in the region affected by tamarisk are actively pursuing, at significant cost, schemes to augment their water supplies:$

11. In considering the spread of saltcedar on western U.S. rivers, it is important to distinguish between inherent competitive advantages that saltcedar may have over native trees, that allow it to displace native trees, as opposed to greater stress tolerance that allows it to replace native trees when a habitat has been altered to the point that it no longer meets the niche requirements of the native trees.

12. Competitor to native trees or greater stress tolerance If saltcedar is primarily a competitor to native trees, then restoring riparian habitats must involve saltcedar removal. If saltcedar is primarily a competitor to native trees, then restoring riparian habitats must involve saltcedar removal. On the other hand, if saltcedar is primarily a stress tolerant replacement species, restoration programs that concentrate on restoring pulse flows might be successful without the need for saltcedar control. On the other hand, if saltcedar is primarily a stress tolerant replacement species, restoration programs that concentrate on restoring pulse flows might be successful without the need for saltcedar control.

13. Three primary strategies for plant growth the degree of competition - defined as “the tendency of neighboring plants to utilize the same quantum of light, ion of a mineral nutrient, molecule of water, or volume of space” the degree of competition - defined as “the tendency of neighboring plants to utilize the same quantum of light, ion of a mineral nutrient, molecule of water, or volume of space” Disturbance is the periodic removal of all or part of a plant's biomass from the activities of herbivores, man, plant pathogens or natural forces such as flooding, erosion and fire. Disturbance is the periodic removal of all or part of a plant's biomass from the activities of herbivores, man, plant pathogens or natural forces such as flooding, erosion and fire. and stress in the environment consists of conditions that restrict a plant's primary production, such as shortages of water, light or nutrients, or the presence of excess salts. and stress in the environment consists of conditions that restrict a plant's primary production, such as shortages of water, light or nutrients, or the presence of excess salts.

14. Under a natural flood regime, western riparian zones can be considered low-stress, moderate disturbance environments Perennial streams have surface flow as well as a high water table within reach of plant roots, hence there is much less water stress than in the surrounding desert habitats Perennial streams have surface flow as well as a high water table within reach of plant roots, hence there is much less water stress than in the surrounding desert habitats Nutrient levels tend to be high compared to the surrounding desert due to the accumulation of litter Nutrient levels tend to be high compared to the surrounding desert due to the accumulation of litter On the other hand, occasional large flood events (return time of 5–10 years) scour the floodplain and rework the alluvium, removing existing plants and creating space for the establishment of new cohorts. On the other hand, occasional large flood events (return time of 5–10 years) scour the floodplain and rework the alluvium, removing existing plants and creating space for the establishment of new cohorts. Cottonwood and willow have been considered to be ruderal, pioneer tree species in the riparian zone, able to establish quickly and form a dominant overstory following flood events Cottonwood and willow have been considered to be ruderal, pioneer tree species in the riparian zone, able to establish quickly and form a dominant overstory following flood events

15. Under a regulated flow regime, riparian zones have tended to become high stress, low disturbance environments Banksides have become saline due to lack of overbank flooding to leach salts from the soil, Banksides have become saline due to lack of overbank flooding to leach salts from the soil, and water tables have declined due to withdrawal of flows to support human activities. and water tables have declined due to withdrawal of flows to support human activities. It has been proposed that reestablishment of a natural flow regime on these rivers might permit passive restoration of native trees, without the need for aggressive saltcedar clearing programs It has been proposed that reestablishment of a natural flow regime on these rivers might permit passive restoration of native trees, without the need for aggressive saltcedar clearing programs

16. The cost to remove Tamarix could be enormous. The terrain is difficult to deal with. One suggested method to remove Tamerix is to bulldoze the plant and its crown roots. The terrain is difficult to deal with. One suggested method to remove Tamerix is to bulldoze the plant and its crown roots. This was one of the least expensive and most effective methods proposed. This was one of the least expensive and most effective methods proposed. Bulldozers on the rugged Colorado leave the question of how do you get the equipment to and from the site. Bulldozers on the rugged Colorado leave the question of how do you get the equipment to and from the site.

17. Chemical control Chemical control in association with chainsawing existing saltcedar more than triples the cost while reducing effectiveness dramatically. Chemical control in association with chainsawing existing saltcedar more than triples the cost while reducing effectiveness dramatically. Application of the herbicide also comes into question as studies performed used fixed wing aircraft to apply the chemicals. This approach is not practical in the Grand Canyon. The use of helicopters is also difficult as well as being a less effective dispersal method. Application of the herbicide also comes into question as studies performed used fixed wing aircraft to apply the chemicals. This approach is not practical in the Grand Canyon. The use of helicopters is also difficult as well as being a less effective dispersal method.

18. The third method of control proposed is the introduction of biological agents such as the leaf eating beetle Diorhabda elongata. The third method of control proposed is the introduction of biological agents such as the leaf eating beetle Diorhabda elongata. This could help to control the present pest Tamarix. This could help to control the present pest Tamarix. However, adaptations by a non native life form could evolve, and this keeps this method as questionable, at best. However, adaptations by a non native life form could evolve, and this keeps this method as questionable, at best. The risk is too high to bring another unknown into the environment if these is an other alternative. The risk is too high to bring another unknown into the environment if these is an other alternative.

20. Cohabitation of Tamarix with native trees of willow and cottonwood trees could help to restore some native species to the banks of the Colorado River This plan is financially reasonable no removal expense This plan is financially reasonable no removal expense The establishment of regular large flood flow is recommended as part of the plan. The establishment of regular large flood flow is recommended as part of the plan. The flooding would eliminate the high stress environment that is currently imposed upon the plant life of the Colorado. The flooding would eliminate the high stress environment that is currently imposed upon the plant life of the Colorado. Studies have show that large volumes of water scour the floodplain of sediment buildup produced by saltcedar. Studies have show that large volumes of water scour the floodplain of sediment buildup produced by saltcedar. These sediments move downstream and reestablish beaches that have eroded due to low level waterflow. These sediments move downstream and reestablish beaches that have eroded due to low level waterflow.

21. The Grand Canyon was shaped by floods it is reasonable to speculate that flooding will help to return the environment to some of its former self. The scouring of the river basin by the extreme water flow will also help to remove any opportunistic plants that have taken up residence. This will reduce the Colorado River banks overall evapotranspiration rates from its present levels.