Conservation

Invasive Species

Tamarix

Description

Tamarix spp. (also known as tamarisk, salt cedar), grows as a multi-trunked, shrubby tree and can grow 25 feet in height. The plant has small, scaly, cedar-like leaves, that are grey-green and turn bright yellow in the fall/winter prior to dormancy. In the spring and summer, tamarisk produces thousands of small pink flowers that can generate hundreds of thousands of seeds per year. The plant is noted for its very deep tap root - up to 20 feet deep!

Problems with Tamarix spp.

Tamarix spp. is most notoriously known for its water consumption--up to 300 gallons a day! The plant's deep tap root can access groundwater, decreasing the availability of water for other uses in the area. Small streams and springs have been known to dry up once tamarisk has invaded the area. Not only does tamarisk out-compete native riparian plants for water, it also competes for space by exuding salts on the soil around the plant, inhibiting other plants from growing. Due to such competition, tamarisk can invade and dominate an area, displacing the native vegetation.

Dense stands of tamarisk can block access to water and narrow stream channels, which results in more frequent flooding. Dense stands of tamarisk also provide excess fuel, which may increase the frequency and intensity of wildfires.

Where is Tamarix spp. in the Parkway?

The most common place to find tamarisk is along Little Dry Creek, a tributary of the San Joaquin. Friant Road crosses over Little Dry Creek, and tamarisk trees can be seen from this location both upstream and downstream in the channel bed. The plant is easiest to recognize in the spring, when the branches are covered with small pink flowers, or in the fall, when the leaves turn bright yellow.

Tamarisk has also been found in Lost Lake Regional Park and in the Milburn Unit of the San Joaquin River Ecological Reserve.

What are we doing about Tamarix spp.?

In Fall 2001, we partnered with Fresno County Parks and Recreation to remove the tamarisk growing at Lost Lake. Through the use of a backhoe and an inmate crew, about 6 mature tamarisk trees and several young trees were removed. Parts of the tap root remain in the ground and still have the potential to resprout. Therefore, the area needs to be monitored periodically over the next several years until the root system is exhausted. In the meantime, the new sprouts are easy to pull by hand.

The next step is to remove tamarisk from Little Dry Creek. We hope to work with the California Conservation Corps and the CA Department of Fish and Game to remove the tamarisk from Little Dry Creek within the Willow Unit Ecological Reserve.

Staff and volunteers work on Tamarisk eradication during workdays.

For more information, read "The Risk of Tamarisk" from the Winter 2002 Parkway Current.