Riparian Zone

Riparian Zone Definition

The riparian zone is one of many different biomes, which represent different communities of flora and fauna. Other biomes include savannas, tropical rain forests, and deserts, among many others. The riparian zone is identified as the area immediately adjacent to running, fresh water. This may be anything from a small trickling creek to a raging river. The plant and animal communities that tend to occupy these regions are similar on every continent, while they may not be related.

The riparian zone is an important biome in the water cycle, as well as in many independent nutrient cycles. The plants and animals in the riparian zone help to filter the water as it passes, helping to increase the water quality downstream. Many conservation projects are focused on protecting or repairing riparian zones, which has the opportunity to greatly impact all of the communities which receive water and nutrients after a riparian zone. Given that all the fresh water in the world flows through one river or another, the riparian zone is an important and significant biome in ecology.

The riparian zone is name for the Latin “ripa”, which means river bank. While the riparian zone is not exclusive to rivers, it is a good way to remember the general plants and animals which occupy the region.

Riparian Zone Characteristics

Geography

The riparian zone is characterized by both its proximity to water and by the plants and animals present. In terms of location, the riparian zone is always directly adjacent to a moving body of water such as a stream, river, or estuary. Depending on the latitude of the river, the riparian zone may be reduced as the temperature gets colder. Since plants cannot grow at the highest latitudes, rivers here have little to no riparian zone. On the other end of the spectrum, tropical rainforests do not have distinguishable riparian zones because the forest encroaches directly on the banks of most rivers.

The riparian zone is most commonly observed in temperate regions with seasons, where the additional water from the stream or river allows large trees and shrubs to grow along the bank. The riparian zone is common along rivers in the plains and savannah biomes, which don’t get enough water from precipitation to grow large trees. Here, the riparian zone stands out and is easily identifiable from the surrounding biome.

Flora and Fauna

Along rivers and streams, animals and plants which are hydrophilic, or love all the water they can get. This is not true of all plants, as many plants would drown if exposed to the intense amount of water at a river’s edge. However, many plants and animals have evolved for this situation.

Large trees like oaks, cottonwoods, ash trees, and willows are prime members of the riparian zone community. These trees provide shelter and rich soil, under which smaller shrubs and vegetation can grow. While the trees limit the amount of light that reaches the stream, they also insulate the stream from experiencing the heating effects of direct sunlight. This increases the biodiversity within the stream, and allows many opportunistic feeders to come to the biome.

Animals like otters and musk rats love the abundance the riparian zone has to offer, as well as the protection it provides from larger predators like wolves and cougars. Other animals include frogs, lizards, and snakes, all attracted by the water and abundance of prey. Many aquatic bird species make their homes in riparian areas, including birds like ducks and dippers.

Riparian Zone and Conservation

As the riparian zone filters and cleans the water we use and drink, they are important targets of conservation efforts. When a riparian zone is destroyed by human activities such as construction, it negatively affects all the biomes downstream. The soil is lost through the effects of sedimentation, causing the land to erode away. Further, agricultural runoff and other toxins which were being filtered by the riparian zone now make their way to reservoirs and to the ocean. Here, they can become harmful to the humans that consume the water and the biomes beyond.

Further, the loss of the riparian zone also removes the shade present over the stream. Exposed to direct sunlight and the temperature changes that entails, most species will have to relocate. This can decimate the biodiversity in a stretch of river or stream. The action will also kill the smaller plants, below the trees, as these also relied on the balance of sun and shade that trees provided. Without these plants, the stream can flow faster. This increases the chance of flooding, which would also be more devastating without the large roots of the plants to resist the flow of water.

However, effective riparian zone restoration has been demonstrated. In a matter of years, areas decimated by human activities can again be thriving ecosystems. Oftentimes, riparian zones are establish on purpose, in areas which need better drainage and protection from the erosive effects of running water. To do this, scientists transplant species into the area and allow them to take root. Once these plants are established, the process of succession takes over, and the community will develop naturally. It is almost like a domino effect. After the first plants begin to alter the environment, they make it easier for the other plants and animals to repopulate the area.

The riparian zone is important to conservation not just from a human stand point, but also of other species. The zone serves as an important wildlife corridor, allowing species to pass without interacting with humans. The continual corridor of trees and vegetation continue for many miles in most cases. These corridors are necessary to maintain the genetic pool present in different species of animals. If the corridors are lost, these animals will not be able to interbreed and the population will become fractured.

Quiz

1. Which of the following is NOT a characteristic of riparian areas?
A. Has very little vegetation
B. Contains a large amount of biodiversity
C. Supports large trees

Answer to Question #1

A is correct. The large amount of water present in a riparian area allows many plants to thrive. This, in turn with the tempering effects of the vegetation, allows a great many animals to survive as well.

2. How is the riparian zone different from the wetland or swamp zone?
A. It is essentially the same
B. The water is moving through the riparian zone
C. The riparian zone does have water

Answer to Question #2

B is correct. Water in the wetland areas is stagnant. It moves very slowly, if at all. In the riparian zone, the water is moving, and quickly. This gives a small buffer area around the stream or river which is saturated with water. The riparian areas are easily defined by the body of water they surround. In a wetland, the boundaries are less obvious, as the water is distributed over a relatively flat area very thinly. Even in a lake, the water moves more and is more bounded than in wetlands.

3. A farmer is perfecting his new field. The field runs on a slope, and at the bottom of the slope is an open river. The farmer is worried about agricultural runoff into the river. What should he do?
A. Stop farming
B. Use only organic nutrients
C. Build a riparian zone

Answer to Question #3

C is correct. Everyone needs to eat, so he can’t stop farming. Organic nutrients don’t solve the problem of runoff. Runoff is a problem because the nutrients make it to the lakes and ocean, where they encourage huge blooms of algae, killing off everything else. The most natural “bio-filter” is a riparian zone. The trees and vegetation use up the nutrients before they enter the river, preventing any large blooms from runoff.

References

• McMahon, M. J., Kofranek, A. M., & Rubatzky, V. E. (2011). Plant Science: Growth, Development, and Utilization of Cultivated Plants (5th ed.). Boston: Prentince Hall.


• New Mexico Forest and Watershed Health. (2018, 5 2). Riparian Zone. Retrieved from All About Watersheds: http://allaboutwatersheds.org/library/kyw-poster-files-and-links/riparian-zone


• Pough, F. H., Andrews, R. M., Cadle, J. E., Crump, M. L., Savitzky, A. H., & Wells, K. D. (2004). Herpetology.Upper Saddle River, NJ: Pearson Prentice Hall.

Riparian Zone