Is the view more important than the health of the river?
by Tiffany Malzahn
Throughout the United States, healthy streams, rivers and estuaries are crucial to the economic, climatological, and environmental viability of areas dependent on watersheds. Which makes it more important than ever that residents understand how poor land management practices such as clear-cutting foliage can affect the physical, biological, and social resources of our rivers. A few small changes could make dramatic improvements to the Brazos River.
Example of riparian restoration by succession on the Nueces River after the prohibition of off-road vehicles in the riverbed (Alldredge, Goodwin, Disctson, and Cathey, 2014).
One of the key components of a healthy stream is a robust and undisturbed riparian zone. The riparian zone is the vegetated area between the river or stream and the higher ground. In the riparian zone, water, soil and vegetation interact. The plants that grow in this zone are distinctly different from neighboring plants that grow naturally on higher ground. They are adapted to living in or adjacent to aquatic environments and can survive periods of being partially or completely underwater. A healthy, undisturbed riparian zone will support a thick stand of densely rooted vegetation that will benefit the property in a number of ways such as:
- Reducing Erosion and Sedimentation in the Stream Channel - Riparian plants have different root structures, which makes them uniquely suited to dissipate energy in the stream channel during periods of high flows. This dissipation of energy stabilizes the stream's banks and reduces erosion.
- Minimizing Impacts of Flooding - Riparian zones collect and store stormwater in vegetation and soil, allowing water to run off slowly, gradually recharging aquifers and surface waters.
- Improving Water Quality - As water from storm events flows from higher areas to streams and rivers, a healthy riparian zone slows the flow of the water and filters out sediment and human pollutants before entering the aquatic system. The riparian zone also moderates water temperatures in streams and rivers, providing shaded areas when it’s especially hot. Water temperature is inversely proportional to dissolved oxygen levels in streams; therefore, when water temperature is high, dissolved oxygen is low. Many aquatic organisms are dependent on high levels of dissolved oxygen to breathe; as a result, healthy riparian zones help support a healthy, diverse aquatic community.
- Providing Habitat for Wildlife – Healthy riparian zones also provide habitat for both aquatic and land species. Habitat fragmentation is often cited as a primary decline of species resilience by the U.S. Fish and Wildlife Service. Fragmentation occurs when land development and management practices remove natural habitat, thus breaking-up continuous areas into smaller isolated remnants. Habitat loss is a detriment to any species, and fragmentation, depending on the species, can hinder or inhibit key life cycle functions, all of which can negatively impact whether or not a species will survive, according to a 2015 article in the Journal of Biogeography.
- Protecting Against Invasive Species Colonization - Disturbance in native communities allows the establishment and spread of invasive species, such as zebra mussels, which can displace and harm native species. Managing and controlling invasive species, once they have established in an area, is a daunting and expensive prospect as these species have no native predators to control their populations. A 2005 study by Pimentel, Zuniga and Morrison-determined that invasive species cause environmental damage and losses in the United States totaling $120 billion per year.
Riparian Health in the Brazos River Basin
The Brazos River watershed crosses eight ecoregions and seven climate zones, supporting a highly diverse ecological community that relies on the quality and quantity of water moving through the system. Sadly, land cover analysis reveals there are 219 miles of damaged riparian area in the Brazos River watershed. This is a result of poor land management practices over a long period of time, that resulted in the large-scale clearing of land for agricultural and industrial activities and urban development. Impacts to water quality and wildlife can be seen across the watershed due to the loss of the environmental benefits a healthy, undisturbed riparian zone yields.
Restoring Damaged Riparian Zones
Riparian zones are amazingly resilient and the natural recovery process can be relatively quick compared to restoring other types of environmental damage. Minor changes to land management will often result in damaged riparian zones restoring themselves over time. Some changes include small things like no longer mowing or clearing to the edge of a stream and creating defined access paths. In areas where the riparian zone has been completely eliminated and erosion is high, a little nudge with seasonal plantings of native riparian vegetation is often all that is required to jumpstart revegetation. In the areas most effected, more intense efforts may be needed, like terracing or rip-rap with plantings of riparian vegetation.
If you’re a landowner that would like to begin restoring riparian zones on your property, there is help available. You can call on the expertise of Texas A&M AgriLife Extension Service, Texas A&M Forest Service, the U.S. Department of Agriculture – Natural Resources Conservation Service, and Texas Parks and Wildlife Department personnel to help you develop a restoration plan for your property.
Brazos River Authority Environmental and Compliance Manager Tiffany Malzahn
Hansen, M.J. and A.P. Clevenger. (2005, September). The influence of disturbance and habitat on the presence of non-native plant species along transport corridors. Biological Conservation 125(2): 249-259.
Hanski, I. (2015, May). Habitat fragmentation and species richness. Journal of Biogeography 42(5): 989-994.
Pimentel, D., R. Zuniga, and D. Morrison. (2005). Update on the environmental and economic costs associated with alien-invasive species in the United States. Ecological Economics 52: 273-288.