Saltcedar or tamarisk is an exotic tree that has become naturalized throughout riparian areas in the southwestern United States and is continuing to expand its range into other western states. Tamarisk has become the dominate plant species throughout several entire river drainages and tributaries in less than 100 years after introduction. The riparian areas of the southwest have been reduced and altered so severely from numerous impacts that they may be one of the rarest habitats remaining in North America. Although this pernicious pest is difficult to control there are proven methods that have succeeded. Saltcedar control management can appear to be overwhelming for many land managers, control projects can be expensive and labor intensive therefore we must choose our battles wisely and use careful planning.
Before developing a tamarisk control program there are several criteria one should address to assist in the decision making process, they include: inventory, objectives, management constraints, priorities, site restoration potential, and control feasibility.
-Inventory: Know the extent of the populations and degree of infestation within your management area. Be familiar with surrounding areas as they relate to management, seed dispersal and reinvasion potential.
-Objectives: What are your objectives? Some may be to keep it from spreading into new areas, or to protect native plant populations that are being threatened with the presence of tamarisk. Others may decide for complete elimination and manage for zero tolerance while some may accept a specified percentage of total vegetative cover.
-Management Actions and Constraints: Are management practices and/or activities promoting tamarisk establishment? Can you implement a wide range of control methods such has heavy equipment, herbicides, prescribed fire?
-Priorities: What are your areas of highest value to protect or eradicate and maintain free of tamarisk? The areas with the highest probability for success should be at the top of the list. The combination of answers to many of these questions will most likely determine your priority. I recommend to start small and work your way up to larger projects.
-Site Restoration Potential: Does the site have potential to restore to the desired plant community by natural processes and/or transplanting? Soil analysis and water table level monitoring may be critical depending on the cost or size of the project.
-Control Feasibility: Can this project be successful considering the answers to the questions above? Is tamarisk the only species that can thrive in the existing situation? Are site conditions altered so severely that they perpetuate tamarisk presence? Is accessibility of location a limiting factor? Site maintenance must be included in management plan for perpetuity.
It is important to realize that saltcedar is here to stay and there are many situations due anthropogenic impacts that few native plants species if any could survive. We have created many artificial situations which has given this alien plant advantages for survival over native plants and their historical habitat. However we should not consider the spread of saltcedar benign, instead this should increase control efforts in feasible areas relating to the above criteria. Although tamarisk was introduced and allowed to spread by human impacts it is also encroaching upon remote and relatively undisturbed riparian areas without any help from humans. Due to the aggressive nature of tamarisk, once established through time this plant will eventually dominate from disturbances both natural and tamarisk caused leading to the formation of impenetrable monotypic stands. These monotypic thickets of tamarisk eliminates native vegetation and many wildlife species that rely upon plant diversity. There are a few small rivers, streams and springs that have survived the assault from development and multiple uses but are still threatened by the consistent encroachment of saltcedar. The integrity of these valuable habitats will never be intact with the presence of tamarisk. These outlying riparian areas should be the main focus of prioritizing control efforts.
When initiating a saltcedar control program one should start with small projects that have high potential for success before taking on a more difficult project. This does not mean that large projects cannot be successful or that all small projects will be successful. Attempting to control tamarisk in large scale projects along a major river may be successful in isolated restorable areas with the use of heavy equipment and prescribed fire but probably not feasible without the use of these tools. The decision criteria can work for all sizes and diverse situations encountered while planning saltcedar management programs.
There has been an increased awareness and concern due to the dramatic reduction in biological diversity caused from saltcedar invasions which has led to the development of more control programs. This overwhelming problem brings forth many challenges for restoration managers, hopefully this decision criteria will aid in prioritizing and developing successful tamarisk management programs.
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