# Presentation: 324911

## Riparian vegetation restoration in the context of 

_*Tamarix*__ control along southwestern U.S. rivers_
- Patrick B. Shafroth
- U.S. Geological Survey, Fort Collins Science Center

## Replacement vegetation

- Tamarix* control*

- Water salvage

- Wildlife habitat

## What will replace Tamarix after control efforts??

- >  Restoration/revegetation post- *Tamarix* control
- >  USGS capabilities

_*What will replace *__Tamarix __*after control efforts??*_

##  Tamarix has a broad

-  *Tamarix* has a broad
-  distribution throughout
-  western N. America.

## Tamarix abundance is variable

*Tamarix* abundance is variable

## Tamarix

- Riparian vegetation with *Tamarix *(DYNAMIC)

*Tamarix*

*Tamarix* control

*Channel *
*modifications*

*Land use*

*Groundwater impacts*

*Streamflow*
*regulation*

*Fire*

*Salinity*

*Other species*

- Novel state(s) (DYNAMIC)

*Active *
*management*

*Climate*

*Extreme*
*events*

**Notes:**
Another flow diagram??

## Factors influencing SW woody riparian spp.

- _Factors influencing SW woody riparian spp._
-  Floods and associated fluvial processes
-  Low flows and alluvial groundwater levels
-  Salinity
-  Fire
-  Climate

**Notes:**
Some key environmental factors include: surface water hydrology, ground water hydrology, salinity, fire, climate

## Floods

- _Floods_
-  Drive fluvial processes
- 	> meandering
- 	> narrowing
- 	> flood deposition
-  create physical disturbance

-  moisten sediments
-  flush salts
-  remove vegetation
*Tamarix has thrived where*
*natural flood regimes have*
*been modified.*

## Low flows

- _Low flows_
-  influence alluvial
-   groundwater dynamics
-  influence water
-   availability

*Tamarix* is relatively
- tolerant of drought

## Soil and water salinity

- _Soil and water salinity_
-  species differ in their tolerances
-  *Tamarix* is very salt-tolerant

## Fire

* **Tamarix* stands carry fire well
-  *Tamarix* is fire-tolerant

## Some common characteristics of successful and sustainable riparian restoration programs...

- 1)  Causes of ecological degradation identified
- 		> What has allowed *Tamarix* to thrive?
- 2)  Understanding of current and future site conditions
- 		> Are the conditions that have allowed *Tamarix* to 	thrive changed?  Are they likely to change?
- 		> What species are likely to thrive under future 	conditions?
- 3)  Clear, specific, and realistic objectives. *Prioritization.*
- 		> Complete eradication is usually unrealistic.
- 4)  Monitoring   Adaptive management

## Restoration and revegetation approaches

_*Restoration and revegetation approaches*_

-  natural revegetation
-  active restoration

-  passive restoration, process restoration
-  hybrid approaches

## Natural revegetation

- _Natural revegetation_

-  *Tamarix* recolonizes
-  annual weeds
-   (e.g., *Lepidium, Kochia*)
-   sometimes, natives

-  e.g., Pecos R., springs,
-           mesquite bosques
-  climate/flow dependant

## “Active” approaches

- _“__Active” approaches_
-  seeding, planting
-  site preparation
-  irrigation, weed control
-  site specific, expensive

## “Passive” approaches

- _“__Passive” approaches_
-  remove stressors, restore natural processes,
-   allow biotic communities to recover on their own
- 	>  natural streamflow and sediment regimes
- 	>  cessation of grazing
- 	>  exotic species removal
*Most successful restoration programs have a passive component.*

## Streamflow management downstream of dams

-  Bill Williams R.
-  Truckee R.

-  managed flooding
-  managed base flows

## “Hybrid” approaches

- _“__Hybrid” approaches_
-  mimic missing natural processes
-  exotic species removal, plus active and/or
-   passive measures

**Notes:**
Add slide from Boulder Creek?

## Assisted regeneration of cottonwood and willow

_*Assisted regeneration of cottonwood and willow*_

- Seed source
*Bare surface*
*Moist surface*
*Gradual drawdown*
- Shallow water table
- Safe from future floods
- Safe from herbivores

*Rio Grande*
*Bosque del Apache, NM*

## Assisted regeneration of cottonwood and willow

- Seed source
*Bare surface*
*Moist surface*
*Gradual drawdown*
- Shallow water table
- Safe from future floods
- Safe from herbivores

_*Assisted regeneration of cottonwood and willow*_

*Former gravel pit*
*Fort Collins, CO*

## Assisted regeneration of cottonwood and willow

*Seed source*
*Bare surface*
*Moist surface*
*Gradual drawdown*
- Shallow water table
- Safe from future floods
- Safe from herbivores

_*Assisted regeneration of cottonwood and willow*_

*Boulder Cr.,*
*Colorado*

**Notes:**
Boulder Creek

## USGS capabilities–riparian restoration

- _USGS capabilities–riparian restoration_
-   ecology and dynamics of western riparian vegetation
-   site evaluation, restoration potential
-   cottonwood/willow restoration
-   streamflow management
-   pre- and post- project monitoring; data analysis

## Conclusions

-  *Tamarix* occupies a very broad range of riparian sites throughout western North America
-  the restoration potential of these sites  is similarly variable, and warrants prioritization and consideration of a variety of approaches
-  the introduction and spread of *Tamarix* is usually not the primary cause of riparian ecosystem degradation
-  successful restoration efforts usually require addressing primary causes of degradation (which tend to favor native species), and do not simply focus on removing *Tamarix *

## Site evaluation

- What is likely to replace *Tamarix?*

*Site prioritization, selection*
- Costs/benefits of vegetation change for water yield, wildlife.

*Revegetation/restoration plan*

- Tamarix* control*

*Pre-project monitoring*

- Restoration/revegetation

*Post-project monitoring*

- Adaptive management

## Slide 25