Friday, February 7, 2014

Riparian Buffers - Reforesting Waterways

Today we are going to write about Riparian Buffers - or planting trees and other plants along waterways.  This may seem like an odd topic given the blog's title of "The Arid Arborist."  However, we feel that the uses of trees should be enumerated at every opportunity, and proper care of our waterways encourages tree growth everywhere.  We will both discuss the uses and challenges of planting along waterways, and ways in which the Groasis Waterboxx may help.

First, what is Riparian Buffer?  A Riparian Buffer is a green zone planted with native trees, shrubs and grasses along a waterway that protect against non-point source (generalized) pollution, inhibit erosion, and provide habitat for wildlife.  These may also serve the very important goal of windbreak and flood mitigation.  Riparian is derived from "ripa" meaning bank in Latin, from which our word "river" is clearly derived.
Riparian Buffer in Iowa - From Wikipedia

Uses of Riparian Buffers

Sediment Removal - In one paper (Mankin, 2007), the authors found that Riparian Buffers stopped over 97% of sediment from entering the waterway.  This same study found over 90% of fertilizer components (which can cause choking algae blooms near the mouth of rivers) were stopped by Riparian Buffers.  The effects of erosion into our waterways can perhaps best be seen at the Mississippi Delta, were millions of tons of topsoil is lost to the Gulf of Mexico.

Windbreaks - While the research on Riparian Buffers as windbreaks is not as robust, the use of trees elsewhere as windbreaks is well known.  If planting for windbreaks in temperate regions (all of the United States), conifers should be used extensively as these will work in winter when deciduous trees have lost their leaves.

Flood Mitigation - Riparian Buffers allow heavy rains to more slowly reach waterways through several mechanisms.  First, plants form physical obstacles to water as it flows downhill (imagine a ball rolling down a flat piece of plywood versus a pegboard with pegs every 2 inches).  Second, the roots of the plants loosen the soil and allow water to percolate downward to underground aquifers rather than all staying on the surface.  Finally, plants transpire (absorb and then emit as water vapor) huge amounts of water, turning liquid water into water vapor.  If the Riparian Buffer is used for flood mitigation, grasses, shrubs and trees are useful.

Litter containment - it is deeply distressing to the author how much preventable litter we see floating into our nearby creeks.  Much of this is unintentional - trash left out for pick up and then blown into a creek by strong winds (another reason for windbreaks), but Riparian Buffers would enable the trash to be stopped before entering the water and becoming a danger to fish and other wildlife.  The trash is much easier to remove near the base of trees rather than from the bottom of a swollen stream, or worse, the center of the Pacific Ocean.

How Can the Groasis Waterboxx Help?

What role can the Groasis Waterboxx play in Riparian Buffers?  We have tried multiple times before the Waterboxx to plant different trees along stream banks.  Our first effort we planted 2  8 foot tall Weeping Willows (Salix babylonica) approximately 5 feet above the level of a nearby creek.  We believed that rainfall would be sufficient to get the willows' roots to the moisture at the water level.  In this we were mistaken.  The summer following planting was very dry, and even weekly watering didn't save our willows.  Next we tried planting both one smaller weeping willow and several bald cypress (Taxodium distichum) right along the water level (during a relatively wet period in spring) realizing that our trees may be washed away in heavy rains.  Our trees were not washed away, but the bald cypress never bloomed due to unknown reasons (possibly because it was in a frost pocket which injured it).  This weeping willow did do quite well for a time, doubling the size of its canopy in less than a year.  However, during a dry summer spell, the water level of the creek fell well below the roots of the willow, revealing that the willow roots were barely in soil and mostly in the creek itself (now in open air).  The willow quickly died.  The Groasis Waterboxx solves both the problem of inappropriate amounts of water and frost pockets.  If we had planted our trees at the top of the creek bank with the Groasis Waterboxx, we would have provided the trees with just the right amount of water to sustain them during dry spells without opening them to flooding that would expose and then kill their roots.  The trees also would have been better positioned to serve their proper purpose in the Riparian Buffer, slowing flood waters and preventing sediment runoff.  You can see a video of how the Waterboxx functions below:

The Groasis Waterboxx dramatically increases tree survival (up to 99% when done properly in one Sahara desert planting trial), and is reusable for up to ten years.  The Waterboxx can be purchased from Dew Harvest in the United States.

More information on Riparian Buffers is available here from the Arbor Day Foundation. We would love to hear your comments below - to leave one, please click on "Comments".

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