Control & Restoration

Managing a tamarisk or Russian olive control and restoration project consists of five components – planning with inventory/mapping, control, revegetation, monitoring, and maintenance. Without all five components it is unlikely that tamarisk control projects will be successful over the long term.

Many strategies for successful tamarisk and Russian olive management are presently being used, and each, alone or in combination with others, is applicable in different instances. A proper assessment of each area must be conducted in order to determine a suitable approach. Successful control and restoration depends on adapting approaches as new experience, research and technology develop. 

The Tamarisk Coalition has completed an assessment of alternative technologies for tamarisk and Russian olive control, biomass reduction and revegetation describing effectiveness, costs, impacts, and applicability. It should be noted that there are many different hybrids of these control and restoration technologies; thus, actual costs and applicability may vary for each site. Wherever herbicides are identified as a component of a control option, the product identified is the one most widely used and the application rate on the product label should be followed.

Below is a brief look at what our assessment of alternative technologies discusses:

Control

In general, available technologies to control tamarisk and Russian olive include five variations of hand, mechanical, and biological control:

1. hand control with herbicide application
2. mechanical extraction without herbicide (not appropriate for Russian olive)
3. mechanical mulching with herbicide
4. mechanical grab & cut-stump with herbicide
5. biological control using the tamarisk leaf beetle, Diorhabda elongata and, where appropriate, goats can be successful

All control technologies, by their nature, require follow-up treatments for resprouts and weed control as an implicit part of the approach.

Biomass Reduction

In general, biomass reduction (or removing tamarisk skeletons following control) should not be needed for light infestations and some moderate infestations but should be performed for all other situations to reduce the fuel load in riparian areas. This is especially important to protect valuable cottonwood galleries and native shrubs from fire.

Revegetation

Revegetation will likely occur naturally following the removal of lightly infested sites with some minor weed control. For moderate infestation removals, some reseeding will be necessary while heavy infestations will require substantial revegetation efforts.

Revegetation efforts are inherently site specific, and will vary, depending on local conditions such as soil type and intended use. Site specific revegetation plans will be developed for those areas requiring revegetation. In general, revegetation efforts for all areas, when required, may consist of:

1. Pole cuttings for cottonwoods and willows in areas with shallow groundwater (less than 10 feet).
2. Longstem planting, using tall pot techniques, to revegetate upper terrace sites with deeper groundwater and no overbank flooding. This approach is very useful for some trees and shrubs such as currants and skunkbush.
3. Broadcast or seed drilling for appropriate grasses and forbs depending on the local site conditions.

For more information visit -

Society for Ecological Restoration - This site provides a reading list for ecological restoration practices, links for many example projects and other resources and support.

Riparian Restoration in the Southwest: Species Selection, Propagation, Planting Methods, and Case Studies - This document identifies the natural processes and managed activities that cause the degradation of riparian lands and provides general guidelines to restore the natural system. It describes methods of selecting appropriate revegetation species, processes for producing riparian plants, detailed planting techniques, and provides case studies of past projects.

Stream Corridor Restoration: Principles, Processes, and Practices - This large and detailed document has a three-tiered design. The first section provides background information describing the basics of stream corridor systems. The second section describes the steps to produce an effective restoration plan. The final section provides guidelines to implement restoration projects.

Guidelines for Planning Riparian Restoration in the Southwest - This restoration guide is intended to address considerations for developing riparian restoration projects and to provide a number of responses or solutions to potential problems.

Guidelines for Planting Longstem Transplants for Riparian Restoration in the Southwest: Deep Planting - This site describes a good technique for revegetating a riparian site that lacks overbank flooding and has a deep water table.

The Pole Cutting Solution - This site provides guidelines for planting dormant pole cuttings in riparian areas of the Southwest. Planting dormant pole cuttings has proven to be a successful technique for establishing many riparian trees and shrub species.

Plant Technology Fact Sheet: Tall-Pots - This fact sheet describes the use of tall-pots to establish plants in areas lacking sufficient soil moisture or irrigation availability to revegetate using more traditional means. A discussion of the structure, usefulness, benefits, and limitations of the tall-pot revegetation method is included.

Weed Suppression

Weed control following tamarisk and Russian olive control and during revegetation efforts is necessary to prevent the establishment of other noxious weeds. In general, weed control for all areas, when required, may utilize herbicide, mechanical and biological control, and preventive measures associated with successful revegetation approaches. The need for weed control will increase proportionately with the degree of tamarisk or Russian olive infestation.

Research shows that if resources are spent only on control with no cohesive approach to long-term revegetation, monitoring, and maintenance, the potential for successful riparian restoration is extremely limited.

 

Additional Resources

When undertaking any weed control and restoration efforts, it is essential to consult and comply with all state, federal and local weed regulations concerning your project area. The Center for Invasive Plant Management (CIPM) has compiled a comprehensive list of state and provincial weed laws, reference links and weed manager contacts for western North America.