(Perma)Culture and Sanity
Trees and the Water Cycle
Water Is Lifeblood
Water is the lifeblood of our planet. In fact from rainforest to desert, prairie to arctic, the amount of water available is the central determinant in classifying ecotypes. No living organisms escape the need for water as the basic chemical framework for all their internal processes.
Yet fresh water accounts for only 3% of the water on our planet (and most of that 3% is frozen at the poles)... meanwhile what fresh water does exist is continually moving back to merge with the salty oceans.
To balance the return of fresh water to oceans, ocean water continually evaporates back into the atmosphere to form the clouds that return fresh water to land as rain. However, isotope studies have shown that almost all oceanic moisture falls as rain within the first 150 miles from any coast.
How, then, do life-giving rains manage to reach the vast interiors of continents?
Plants' Moist 'Breath'
As soon as rain falls to the ground, plants begin to absorb the water into their bodies. However, plants must absorb much more water than needed strictly for metabolic use since plants also lose water through evaporation and transpiration ('evapotranspiration'). Water lost to the air through evapotranspiration by trees is the major mechanism through which air is remoistened as it moves farther inland from oceans.
If plants didn't lose so much water to evapotranspiration, the interiors of all the continents would be huge deserts (this is the situation in Australia, where severe deforestation has left the entire continent with only a narrow band of non-desert lands bordering the coast).
"The sky is held up by the trees.
If the forest disappears, the sky-roof of the world will collapse.
Nature and man will perish together."
American Indian Proverb
Trees Humidify Air
Among plants, trees are by far the most effective evapo-transpirers. Complementing oceans, trees form the other half of the planet-wide system known as the rain or water cycle. A typical tree breathes out 250 to 400 or more gallons of water per day through the amazingly large surface area of its leaves (an acre of forest can contain well over 1,000 acres of leaf surface area).
It's almost impossible to overstate trees' ability to humidify air and thereby maintain the rain cycle far from oceans. While some rainfall evaporates directly from the ground and from small plants (this can amount to most of a light rain), evapotranspiration by trees accounts for the great majority of inland rain.
Even near oceans, trees are vitally important to re-humidification and rain. When European settlers removed the high forests from the island of Maui, for instance, the once heavily-forested island immediately downwind (Kahoolawe) quickly became a desert island because its source of rain had been the trees on Maui—not the ocean surrounding both islands.
No Trees, No Rain
If trees are clearcut over large areas, therefore, rains slow or stop downwind, describing the situation existing now over most of the U.S. Southwest. This has not always been the case here, even relatively recently. Our present Southwest is drier than that of just a couple hundred years ago—remember, our popular view of the Old Southwest comes from cowboy movies, all filmed in modern degraded landscapes.
Ancient Tree at Angor Wat, Reclaiming Slightly-More-Ancient Temple.
Tree ring, pollen and other botanical studies, as well as reports by Spanish explorers, show that the Southwest of the recent past was much greener and more productive than it is now. Just 3,000 years ago (a mere drop in the ocean of geologic time) the Southwest was more heavily forested and rainfall was 1½ or more times as plentiful. Grasslands, sprinkled with individual trees and mottes (small islands of trees), were healthy and lush and loss of rain to runoff was very low.
Humans And Desert Formation
3,000 years ago, neither the Sonoran nor Chihuahuan deserts extended northward from Mexico into what is now Texas, New Mexico and Arizona (they both occur naturally in Mexico due to rain shadows created by the Sierra Madres).
Native American burning of prairies (to favor grasses over trees for buffalo forage) started the process of deforestation—and then desertification—which allowed the Sonoran and Chihuahuan deserts to begin creeping northward. Even so, early Spanish explorers found most of the Southwest a healthy, productive mix of alternating meadows and woods. Soon, however, extensive logging and over-grazing began to accelerate the processes of deforestation and desertification begun by Native American burning.
Development also took its toll. Entire forests were cut across the Southwest for use as track ties in the transatlantic railroad; Albuquerque, NM, now desert, is named for the white oak trees that once covered the Rio Grande flood plain before being eradicated by European settlers. Wholesale tree cutting (aided by over-grazing) turned a land of once-great pastoral richness into a place where the weight of the grasshoppers in a given area literally far exceeds that of the cattle. As the trees went, so did the water.
Nixon's Sec. of Ag. Earl Butz
Deserts Don't 'Stay Put'
Desertification, which progresses in the direction of prevailing winds, is by nature more easily prevented than cured. This is because the very existence of a desert slows or stops rain in downwind areas. As a result, downwind forests are slowly starved of water and engulfed by the moving desert.
All deserts grow along their leeward edges unless some geographic feature—ocean, mountain range, etc.—intervenes to stop the process. In fact, according to an article on desertification from South Africa's University of the Western Cape, desertification worldwide renders an area of 12 million hectares (roughly the size of England) useless for cultivation annually.
In semi-arid prairie regions, deserts can easily form if the few trees are removed. Our Midwestern US farming regions will probably become desert when irrigation stops because the trees once preserved as windbreak throughout the region are gone—eradicated in the 1960's by Nixon's Agriculture Secretary Earl Butz' probably well-meaning but misguided 'Fencepost to Fencepost' plowing program.
Stewardship vs Pillage
We must learn to think and see in terms of processes instead of static views if we want to survive. We must protect wilderness areas from human intrusion because of their intrinsic value, and more prudently manage the forests in which we do allow cutting. Remember, we haven't inherited the land from our parents, we've stolen it from our children… let's begin working to give it back. Let's begin to change our idea of 'dominion' over the Earth to one of stewardship—similar in meaning, but deeply different in results.
Reprinted from (Perma) Culture and Sanity Website
Trees and Your Environment
We're proud of the thousands of trees we have been responsible for planning through donations to Trees for the Future . Here's a look at why we think that trees are important at Clean Air Gardening, and why we'll continue planting more of them.
Planting trees in your neighborhood really is one of the best things you can do for the local environment and for the planet. It’s no secret that trees help the environment, but you may be surprised by all the benefits that planting trees can provide. Besides producing oxygen and removing carbon dioxide and contaminants from the air, trees have many other social, economic, and environmental benefits.
Environmental Benefits of Planting Trees
Trees are like the lungs of the planet. They breathe in carbon dioxide and breathe out oxygen. Additionally, they provide habitat for birds and other wildlife. But that’s not all trees do for us! To see just how much trees are essential to the planet and to humans, let’s look at the following statistics:
- CO2 is one of the major contributing elements to the greenhouse effect. Trees trap CO2 from the atmosphere and make carbohydrates that are used for plant growth. They give us oxygen in return. According to ColoradoTree.org, about 800 million tons of carbon are stored in the trees that make up the urban forests of the U.S. This translates to a savings of $22 billion in control costs. Mature trees can absorb roughly 48 pounds of CO2 a year. The tree in turn releases enough oxygen to sustain two human beings.
- Trees also help to reduce ozone levels in urban areas. In New York City, a 10 percent increase in urban canopy translated to a reduction of peak ozone levels by around 4 parts per billion. (Source: Luley, Christopher J.; Nowak, David J. 2004. Help Clear the Smog with Your Urban Forest: What You and Your Urban Forest Can Do About Ozone.)
- Trees reduce urban runoff and erosion by storing water and breaking the force of rain as it falls. The USDA reports that 100 mature trees can reduce runoff caused by rainfall by up to 100,000 gallons!
- Trees also absorb sound and reduce noise pollution. This is especially important for people who live near freeways. In some cases, a well planted group of trees can reduce noise pollution by up to 10 decibels. (Source: New Jersey Forest Service.)
How Trees Help to Save Energy
Planting trees can also help cool your home in the summer. The Arbor Day Foundation states that the overall effect of the shade created by planting a healthy tree is equivalent to 10 room-size air conditioners running 20 hours a day!
In the winter, trees can act as windbreaks for your home and will help you save on heating costs. The Journal of Horticulture claims that saving on heating costs can reach as much as 25 percent!
Trees shade buildings, streets, and homes. If enough trees are planted in cities, the overall microclimate improves and total energy use for heating and cooling is reduced. The EPA has some great information on how planting trees and other vegetation can help to reduce the overall high temperature of your city!
Social and Economic Benefits of Planting Trees
Health Benefits of Nature
Just being around trees makes you feel good. Can you imagine your community without trees? Trees, especially in urban areas, have numerous social benefits. For example, the addition of trees to a neighborhood or a business district can greatly improve the mental and physical health of residents and workers. In fact, the University of Cambridge did a study on job satisfaction of employees of business with a view of trees from their office. They found that these employees suffered from fewer diseases than workers without a view of trees. See here for more information on the study.
Another example is with children with learning disorders. As a form of therapy, children that suffer from Attention Deficit Hyperactivity Disorder (ADHD) can benefit from the presence of trees and other greenery. Kids with ADHD have been proven to be calmer, more responsive, and better able to concentrate when in a space with lots of trees. (Source: Taylor, A.F.; Kuo, F.; Sullivan,W. 2001. Coping with ADD: The Surprising Connection to Green Play Settings. Environment and Behavior)
Trees and their Benefits for Neighborhoods
Additionally, have you considered that planting a tree can significantly increase your property values? As an example, the U.S. Tax Court recently calculated a value of 9 percent ($15,000) for the removal of a large black oak on a piece of property valued at $164,500. (Source: Neely, D., ed. 1988. Valuation of Landscape Trees, Shrubs, and Other Plants.)
Houses with trees are also more attractive to visitors, potential buyers, and neighbors. Neighborhoods with lots of trees also report less crime! (Source: Kuo, F.; Sullivan,W. 2001. Environment and Crime in the Inner City: Does Vegetation Reduce Crime? Environment and Behavior 33(3).) There is no doubt that if you plant trees in your community, people will see and feel the difference.
As you can see, it's clear that trees are essential to our life on the planet. The great thing is that we as humans can play an active role in planting trees to help offset deforestation and urbanization. Not only can you plant trees in your yard, you can also get involved in local tree planting activities on Arbor Day.
If you need more reasons to plant trees, the United States Department of Agriculture has a complete list of statistics regarding the environmental, economic, and social benefits of planting trees. Some of the statistics from this article are included in the PDF file referenced above, as well as many others.
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