Matthew F. Stephens
County Agent, Jackson Parish
I was waist deep in a cypress swamp wishing the ducks were flying during the Christmas holidays thinking about how technology has made duck hunting much more comfortable. I can remember 30-plus years ago wearing uninsulated rubber waders, insulated coveralls, a red “union suit” (that was the undergarment of choice) and still feeling like I was going to freeze to death. We had so many layers of clothes on that it was hard to wade through flooded woods, swamps, etc. without a mishap. Nowadays, we have products like “Under Armour” underwear and neoprene waders that weigh a fraction of what the old waders did with many times the insulation value that allow you to move more freely while staying warm. Staying warm, while standing waist deep in water during 30 degree weather, is a health benefit for us humans. Then it occurred to me that our creeks, ponds, streams and rivers have also realized healthy benefits due to technology. They also need something over them to keep out or filter harmful outside presences. What creeks, streams, rivers, ponds, etc. need to remain healthy are riparian buffer zones covering them like insulated coveralls on us.
In general, riparian buffer zones can be defined as herbaceous zones along streams, rivers, creeks or any other water body. Also known as streamside forests, these riparian buffer zones have a very diverse selection of vegetation that provides numerous benefits to the streams they border, as well as to the selection of wildlife that find shelter in their unique environment.
Perhaps one of the most important qualities of the riparian buffer zone is its ability to control erosion, and thus to prevent sediment pollution. While we often think of pollution in terms of toxic chemicals and waste, sediment pollution is a very large and very significant problem and actually the number one pollutant of Louisiana water ways. Erosion is a natural process, yet it is often sped up through human activities either directly or indirectly.
In a stream surrounded by a riparian zone, sediment pollution is controlled. Riparian zones are densely populated, and thus have an intricate root system that helps to stabilize the bank and prevent erosion. In addition, the woody stems and grasses help to physically trap sediment by slowing down the water runoff from the surrounding area, allowing the sediment to settle out. A stream with these characteristics will tend to be deeper and narrower because the banks are stable and sediment is not filling the stream bottom. This type of environment allows fish and insect populations to thrive.
In contrast, a stream in which the riparian zone has been cleared erodes easily as the vegetation by the stream, if any, has shallow and weak root systems. These systems do not trap the sediment, nor do they hold together the stream banks. Thus, these streams are characterized by wide, shallow streams resulting from the erosion of the banks and the sedimentation of the streambed. In addition, the combination of a lack of vegetation for shade cover and a shallower stream leads to a dramatic increase in water temperature that neither the fish nor the microbes can survive. While these qualities alone are not suitable for fish populations, the increased sediment in the stream water also clogs fishes' gills, covers their food on the stream floor, buries their eggs, and clouds the water, depriving the aquatic plants of light. In addition to the direct impacts on fish, the sediment carries other problems. As the larger pebbles settle out, the finer sediment is carried further downstream, where it can build up and create similar problems in the fish habitat. Sediment particles are most often made of clay whose ionic charge allows other pollutants, such as chemicals, to adhere to them and be transported further down stream.
Nutrient utilization and filtering by riparian buffers are also very important to the water body’s health. Nitrogen and phosphorous are usually the limiting factors in primary production for stream bank vegetation. However, too much nitrogen and phosphorous can have adverse effects on the health of the stream. In high quantities, they are toxic. It is essential, then, that a balance is maintained, allowing the stream to remain healthy. A stream with a riparian buffer zone is able to maintain more natural inputs of nitrogen and phosphorous into the water bodies, therefore keeping a healthy balance. Water bodies with no buffers are poor controllers on nitrogen and phosphorous. Instead of breaking down the nitrogen through de-nitrification, and or taking up the phosphorous in plant materials, most of these nutrients will flow into the stream as during storms as run-off. This influx of nutrients, including nitrogen and phosphorous, serves to promote algal blooms and eutrophication. The result of these two occurrences is a decreased amount of dissolved oxygen available for fish. Riparian zones, and wetlands in general, act as a buffer against floods. Besides slowing down run-off that enters the stream, decreasing the flow velocity of the stream, the zones also serve to soak up excess water through their root systems, thus controlling floods. Although floods are necessary for the diversity of life in the flood plain and riparian zone, a stream with a mature riparian zone controls flooding, keeping it at the moderate levels which help to stimulate growth.
Current research has shown that riparian buffer zones filter out over 95 percent of certain chemical pollutants that otherwise would have made its way to the stream. There has been extensive research conducted showing the amount of pollution that can be stopped from reaching these water bodies merely by leaving vegetation and trees along our water bodies.
Technological advances have improved both our and our water bodies’ health and increased our life expectancy. It is up to us to implement what the technology as taught us. Streams need clothes too.
For more information about riparian buffer zones or any other water quality issue, contact your local LSU AgCenter Office or visit the LSU AgCenter Web site.