Fact check: State Reps say trees steal water

2014-07-30T12:12:00Z 2014-07-30T15:22:52Z Fact check: State Reps say trees steal waterChrista Elise Reynolds Arizona Daily Star Arizona Daily Star

David Gowan and David Stevens, incumbents for the Legislative District 14 House race say being water-wise, especially at the state level, is important for Arizona. After all, Gowan points out, “Water is the essence of life.”

Part of their platform includes acting as a watch-dog for water use in Arizona. Gowan voted in committee to approve a bill that creates a state fund to help remove tamarisk and mesquite trees, and the bill became law this week.

Gowan said: In a phone interview, the team claimed some plants can “siphon the water from underground.” This “water could be saved and used in other aspects,” said Gowan. The team also listed some trees that use too much water, including mesquite in the category of non-indigenous, water-wasting plants.

True or false? Are mesquite water-wasting, non-native trees in Arizona?

Some mesquite are native, but none of the varieties steal water from aquifers.

Three types of mesquite are found in this region. The Velvet mesquite is indigenous to Arizona. The hybrid mesquite and Chilean mesquite are non-native plants in Arizona.

“The Velvet Mesquite is a ubiquitous feature of our region and in my mind just as iconic as the saguaro. It’s twisted branches and shaggy bark offer interesting form and structure to any landscape as well as cover and forage to native wildlife,” writes Erik Rakestraw, horticulturist at the Arizona-Sonora Desert Museum in Tucson.

When established, a velvet mesquite’s deep roots help it stay strong during monsoon winds. They generally need less maintenance than hybrid varieties because of their slower growth. It’s also well-suited for the Sonoran desert environment and “may require less supplemental water,” Rakestraw explains.

Rakestraw always recommends using native Velvet mesquite in landscaping and planting.

Hybrid varieties may have the reputation of needing more water, as they are often planted in developed, landscaped areas, Rakestraw says. Extra irrigation may push the trees to grow faster, ultimately leading to a less-developed root system and making these hybrids more susceptible to tipping over in high winds.

But these hybrids aren’t generally found in desert areas or remote areas, away from landscaping, says Brian Powell, Program Manager for the Pima County Office of Sustainability and Conservation.

The issue of mesquite growing in grasslands is a complicated one, Powell explains, which can be partially traced back to the proliferation of livestock in the late 1800s. Hundreds of thousands of cattle “denuded the landscape,” Powell says, eating the lush grass. After much of the grasses were gone, mesquite had more space to grow. The changes in the grasslands can’t be pinned down to one cause or another, instead, there were many variables affecting the changing vegetation.

Mesquite and other trees do not tap into groundwater or reserves, Powell says. The trees help lessen erosion and keep soil in place. Without the trees, we would see “heavier flooding and more damage if the mesquite were cut down,” Powell says. The trees actually can help slow down the water by holding soil in place, which can help the water trickle down to underground aquifers.

It’s important to look at the whole picture, Powell says.

Christa Elise Reynolds is a University of Arizona journalism student who is an apprentice at the Star. Contact her at starapprentice@azstarnet.com

Copyright 2014 Arizona Daily Star. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

About this blog

The Arizona Daily Star's Pueblo Politics blog includes stories and related items from the Tucson and Pima County political scene written by Star reporters Becky Pallack and Joe Ferguson.

Have a political topic you would like to see in the blog or suggestions? Email Becky Pallack at bpallack@tucson.com and Joe Ferguson at jferguson@tucson.com

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