Salt cedars were introduced into North America in the early 1800s as an ornamental. But since that time, it has wreaked untold havoc on North American waterways.
Salt cedars or tamarisk (Tamarix aphylla,Tamarix parviflora and Tamarix ramosissima) are absolutely beautiful trees. They have long, elegant branches and smooth reddish-brown bark. In spring, the branches are tipped with deep pink and white flowers. They border most of the great rivers, streams, lakes and reservoirs of the North American west
But they are some of the most destructive plants ever unleashed on North America.
What’s so bad about salt cedars?
First, they are allelopathic. Salt crystals that form on their stomata drop to the ground beneath the plant, poisoning the soil in increasingly larger circles. Few plants can survive around salt cedars. None can survive for long.
Secondly, they are facultative phreatophytes. That’s a mouthful. Phreatophytes are drought-tolerant plants that send long deep roots (30 feet is not unusual) to exploit groundwater deposits. But they are also facultative, which means that in addition to those deep roots they send out other roots to seek out any other sources of water, ground or surface. These “advantageous” roots can be extensive.
Salt cedars are highly fire resistant. At the same time, they encourage fires. That’s because they kill or weaken native species, making those species susceptible to fire damage. When fire does come, the salt cedars survive, and the other weakened species die. Then, salt cedars take over the niches of the native plants.
They increase flooding and erosion. Salt cedars grow in tight, impenetrable clusters. Since they like to grow along waterways, which give them as much water as they can take in, they expand their clusters along the streambeds, narrowing and choking channels. When higher water comes, it cannot go through the narrowed channels, so it spreads out and floods. Erosion happens through the same process.
Although the plant does provide some food and cover for native wildlife, there are indications that the number of successful bird species dwindle in proportion to the expansion of salt cedar.
First introduced as an ornamental into North America in the early 1800s by East Coast nurseries, it quickly spread outside of gardens. By the mid-1900’s, many westerners were using it to control erosion along river banks.
But by the 1960s, it had spread throughout the west, replacing native species, causing flooding and erosion.
Salt cedar can grow from sea level to 7,000 feet, which makes it hardy in many climates and cold-hardiness zones.
In some areas of North America, salt cedar has replaced over 70 percent of native species.
Ironically, humans have created and enhanced conditions to allow this species to become so successfully invasive as it has.
Clearing land, plowing, overgrazing, off-roading and tree-logging are some of the plant’s major enablers.
Construction of dams and reservoirs, river and stream diversion, disruption of natural water flows and low water levels are also major causes for the spread of salt cedar.
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