Trees and Water

During the recent drought years homeowners have become unsure about the wisdom of planting new trees. Some municipalities have even placed a ban on planting trees. While the drought has provided us with an opportunity to carefully assess our landscaping needs, the concern about water use for new trees is based on a lack of good information.

Water Use Facts
• Residential use, both indoors and outdoors, accounts for only 10% of state water consumption.

• Agriculture consumes 85% of California's water. With the installation of efficient irrigation systems, farmers could save enough water in one day to sustain one million trees.

• Lawn watering consumes 3.6 % of our state's water. The amount of water used by only 1000 square feet of turf could plant almost 100 new trees.

• The entire urban forest of California uses less than half of 1% of the state water supply.

• A new tree requires only 10 gallons of water per week for its first three years of life. That's equal to two toilet flushes each week or 520 gallons per year.

• It takes 500 gallons of water to bring you just one serving of chicken and 2,500 gallons for one serving of beef.

Why Plant Trees During a Drought?
Some scientists argue that we are not actually in a "drought", but rather, we live in a desert climate and are simply experiencing a phase of this climate zone. This debate aside, there are many compelling facts that support tree planting in these times:

Trees conserve water.
Shade from trees reduces water evaporation from surrounding plants and lawns. Trees improve the condition of the soil, increasing its ability to retain moisture. When it rains, trees allow water to penetrate into the aerated root zone.

Trees conserve soil.
Trees allow rainwater to trickle down to the water table, instead of running off and creating floods and silt in rivers. Erosion is prevented as the roots hold on to the earth on hills and slopes. Topsoil is saved.

Trees are the most water-efficient element in a landscape.
Young trees need only ten gallons of water a week, the equivalent of two toilet flushes. Older trees do fine if watered deeply every two or three months during the dry season (25 gallons at a slow drip). In the average urban landscape, 99% of all irrigation water is used on lawns and other plants.

Trees bring more rain.
Trees are a part of the rain cycle, evaporating moisture for cloud formation and creating a climate that encourages rain to fall. Deforested areas receive less yearly rainfall than places where trees have been planted.

Trees are essential to our communities.
Trees clean the air, produce oxygen, cool the streets and help save energy by cutting air-conditioning use. Trees are often the only greenery that city-dwellers come into contact with on a day-to-day basis. In an urban setting, they provide a psychological boost and a valuable connection to the natural world.

Drought-stressed trees cost money.
Without sufficient water, trees become more susceptible to disease and pests. The cost of treatment can run as high as $1,000 per tree--much higher than the cost of the water needed to keep them healthy.

Trees represent a wise long-term investment.
Trees are usually the most long-lived and valuable element in your landscpae. A dead tree can cost hundreds or thousands of dollars to remove, and 15 to 30 years of growing time to replace. If you feel you need to cut water use in your yard, consider not watering your lawn. A newly planted lawn takes only two months to become re-established.

Saving Water for Trees
Here are several easy ways to save water for your trees:

• Each time you don't flush your toilet, over 5 gallons of water goes down the drain. If you don't flush just two times per week, that will save enough weekly water for your new tree. Or if you install a tank displacement bag, you can save 2 gallons each time you flush.

• Turning off the faucet while you brush your teeth saves almost 5 gallons each time you brush. That adds up to 70 gallons per week, enough weekly water for 7 new trees.

• Filling the sink to shave saves 19 gallons per shave. That totals 133 gallons of water saved, that can provide weekly water to 13 new trees.

• A flow restricted showerhead saves 20 gallons each shower. That's 140 gallons per week. Each new tree needs 10 gallons of water per week, so the amount saved could provide weekly water for 14 new trees!

• Rinsing all the dishes all at once instead of leaving the water running saves 25 gallons each time you do the dishes. During an entire week of dinner dishes, you could save enough to provide weekly water for 17 new trees.

• Don't waste water outdoors - fix leaky hoses, water between 8 pm and 8 am, install bubblers and drip systems for plants, and watering tubes for trees.

• Design a water- efficient landscape, using native plants and trees

Information sources include "Tree Planting and Care During A Drought", TreePeople

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