Trees and Water Conservation: Do They Help or Hinder?

I assume you’ve heard that water is an increasingly precious resource; that supplies of fresh water are shrinking, and that it is vitally important to find a solution for future generations. Some of our favorite missions focus on providing or improving access to clean water for communities with shrinking or insufficient access. All life on planet earth struggles in water’s absence, and thrives in its abundance. (flooding being the exception)

How can we have “peace like a river” if river health declines? Moving water (rivers, streams, oceans, rain, waterfalls, etc..) produces negative ions. As far as I know, all life thrives in the presence of negative ions. Plants grow better. Humans feel better both physically and emotionally. Animals seem healthier. This means that it is not only the presence of water, but also the natural cycle of water that is important.

I love trees. Don’t you?

I have always learned that trees help stabilize an ecosystem by holding water, preventing erosion, and insulating from extreme temperature swings by producing shade and preventing evaporation. (water is excellent for thermal stability) Time and time again, it has been said that trees hold water in the ground. However, I have recently come across some ideas that seem to run contrary to this belief. Frankly, I’m just not sure what to make of it. Both schools of thought come from years of observation and experience. I call these two categories “Prairie Naturalism” and “Rainforestation.”

(Fire-Free) Prairie Naturalism

I first read about this just last week. I don’t remember where I first saw it mentioned, but it linked to a discussion thread in an online forum. In all of the complaining I saw in the discussion last week about “too many trees in Texas,” no one distinguished between species (let alone genus, family, order, class, or division). After a lot of searching, I never found the site where I first saw this idea referenced. However, I did find what I think might be the original source of the idea for the discussion: Why We Chop Down Cedar Trees

In the context of a grassland prairie (such as the Blackland Prairie on which we live), the notion seems to look fairly sound. Native people in this region used to start grass fires as a form of land management. I have seen a lot of reference to fires being not only beneficial, but even necessary. I have also read that periodic fires actually enhance the production of human food in a forest system. I don’t want to go into details for why that is, but I believe it has to do with eliminating competing species. In fact, I have read that these historic intentional grass fires are part of why the Blackland Prairie clay soil is, well… black.

The cedar tree mentioned in the above article is most probably Eastern Red Cedar: juniperus virginiana. This species is actually a juniper, and is considered invasive. There are a lot of people who are allergic to its pollen. It is said to burn hot and fast, which makes it especially vulnerable to wildfires when in drought. Its invasive nature competes with grasses. Eastern Red Cedar’s tolerance of bad growing conditions means they sprout and grow wherever they please. When you are a rancher who relies on grass for your living, this can be a problem. But then, so can any tree that competes with grass for water.

From Wikipedia.org:

“It is a pioneer invader, which means that it is one of the first trees to repopulate cleared, eroded, or otherwise damaged land.”… “In many areas the trees are considered an invasive species, even if native. The fire intolerant J. virginiana was previously controlled by periodic wildfires.”… “Grasses recover quickly from low severity fires that are characteristic of prairies that kept the trees at bay. With the urbanization of prairies, the fires have been stopped with roads, plowed fields, and other fire breaks, allowing J. virginiana and other trees to invade.”

Perhaps the cedar being chopped down by “Marlborough Man” on The Pioneer Woman blog is Ashe Juniper: juniperus ashei, also known as “Mountain Cedar”. From Wikipedia.org:

“Although Ashe juniper is native to central Texas, it is considered a weed by many landowners and developers in that area, especially by ranchers because overgrazing by cattle selectively removes competition when they avoid the bitter-tasting juniper seedlings. This allows for a high rate of juniper establishment and reduces ranch yields.”

The root systems of these trees are rather shallow, and far spreading. The roots are fibrous, and excellent for erosion control. The trees are drought tolerant, cold tolerant, evergreen, and can thrive in almost any soil condition. In short, these are some tough trees. The heart wood is red and aromatic, and repels moths. It is used in furniture building, closet lining, and log home building. It’s resistance to rot makes it a top choice for fence poles. Several Native American tribes consider it to be of importance, with numerous medical uses. Baton Rouge, LA (translation: Red Stick) is named for its prominence in the native groups. The Cherokee tribe(s) considered it to be sacred. The trees are a favorite for several bird species as a source of food and nesting material.

Ranchers and farmers in grassland regions (like the Blackland Prairie) consider it a nuisance. Cattle don’t like it for its bitter taste. They don’t die easily, unless cut down. They have shallow roots, which compete with other shallow root species (i.e. – grasses) for water. In a region where wildfires used to be a normal part of the natural cycle, these resinous, highly flammable trees (yes, even live) were fuel. When a region accustomed to wildfires is protected from them, the tree-fuel becomes the problematic threat to the ecosystem. In fact, The Native Plant Society of Texas and the Native Prairie Association of Texas had this to say bout the Blackland Prairie:

“Dr. John Brooke, in 1848, described the region as he entered the area: ‘It was the finest sight I ever saw; immense meadows 2 or 3 feet deep of fine grasses and flowers. Such beautiful colors I never saw…'”

“Now very little of the native Blackland Prairies remain due to the destruction of the prairie by plowing for agriculture, abusive overgrazing, and development. The lack of management with natural or prescribed fire has also allowed native prairie to be destroyed by brush invasion.”

All that said, I don’t blame the ranchers and farmers in our region for hating prairie trees. However, is it possible that we are doing it wrong? Is it possible that there is a better way of ecosystem management? That’s hard to say. I’m not writing this to make a case or present an argument. This is new information to me, and I’m just sharing my thoughts as I hash them out here. The contributions of more thinkers are welcome.

Rainforestation: Plant More Trees

This is the view I had long held: Plant More Trees. In response to the accusation that “too many trees dries out the landscape,” and that “Texas has too many trees”, I’d like to mention a few things. Most of the trees planted here are deciduous (they lose their leaves in the fall). Deciduous trees are not like evergreen trees (pine, spruce, juniper, cypress, etc..) in many ways. One of the biggest benefits of a tree in a hot climate is shade. Have you ever heard of an evergreen referred to as a “shade tree”?  Me neither. Why is shade so significant? Consider this: a patch of turf (grass, lawn, ground-cover, etc..) reads 15F cooler in the shade. Micro-climate humidity is increased by as much as 41%. A tree’s physical mass is comprised mostly of carbon taken from the air (carbon dioxide). Trees are used as a building material, fuel for heating homes, and mulch for protecting soil. Fallen leaves add a tremendous amount of beneficial fungus and fine particle deep soil minerals back to the topsoil, and naturally help prevent groundwater evaporation. The canopy takes the initial impact from rain, preventing soil compaction, and ultimately preventing erosion and water runoff. Yes, trees give off water… but they also help retain a lot of water.

The removing of trees from the rainforest in Brazil is actually turning deforested areas into an infertile desert. This is, however, what happens when trees are removed from their native spot, and may not translate well into an argument for establishing trees where few exist. It does, however, shed some light as to the importance of trees and the micro-climates they create.

Of course, not every tree is appropriate for every situation. For example, shallow root trees are prone to die in the hot, dry conditions of summer in Texas, and dead trees are dangerous in urban or suburban areas. Not to mention, those that don’t die are preventing the replenishment of the water table since the shallow roots are sucking water from the top soil before it has time to really soak in.

Conclusion?

I am not prepared to draw one. I think the whole argument is misunderstood, and a potential example of throwing the baby out with the bathwater. My impression is currently that some trees are beneficial, and others are not. The reality is that we do not have the native prairie that was once here. We have an increasingly populated area, and humans (and their cattle) aren’t so tolerant of the wild and prescribed fires that were once the means of prairie maintenance. After the state-wide drought of 2011, I know we all have a lot to learn.

I am very interested in thoughts of others who have more experience (or well thought-out opinions). Thank you for reading, and don’t forget to share and comment.

Cheers!

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