Chapter 1: Defining Arizona’s Riparian Areas and their Importance to the Landscape

Importance of Riparian Areas

  1. Riparian areas are considered the most productive habitats in northern America and “ribbons of life.”
  2. In the arid western United States riparian areas are less than 2% of the total land area. In Arizona, some estimate that riparian areas are only 0.4% of the total landarea.
  3. The role of riparian areas is disproportionate to their size because of the many ecological functions and multiple uses of riparian areas.
  4. Although functions and values are used interchangeably by many they are different.
    •  Functions describe the ecological, hydrological or other processes that contribute to the maintenance of the system.
    • In contrast value is the worth, desirability or usefulness to humans. Values can change with time while functions are constant.
  5. The most important ecological functions are:
    • Fish and wildlife habitat
         
         Figure 1.2. Fish, birds and large mammals
         depend on riparian habitat      .
    • filtration and retention of terrestrial upland sediment,
    • reduction of chemical inputs from uplands by immobilizing, storing, and transforming them,

        Figure 1.3. Overland flow
    • Stabilization of stream banks and build up of new stream banks,
          
         Figure 1.4 Unstable stream banks and
         stable       stream banks.
    • Increased water storage and recharge for subsurface aquifers &
    • Reduction of floodwater runoff

        Figure 1.5. Flooding
  6. The most important values are:
    • Improving water quality and increasing water quantity, primarily by reducing nonpoint source pollutants. This relates directly to the Clean Water Act of 1972 (amended 1977) and the subsequent development of Total Maximum Daily Loads (TMDL) program by United sattes Enviromental preotection Agency (USEPA) to regulate water pollution. The objective of these are to regulate and mitigate pollutants in streams. Links to the:

      Clean Water Act http://www.epa.gov/region5/water/cwa.htm

      and TMDL's http://www.epa.gov/owow/tmdl/intro.html
         
      Figure 1.6. Excessive sediment in stream water. Sediment is one of the major nonpoint source pollutants in the United States.


        Figure 1.7. Excessive nutrients in the stream
        lead to excessive algal growth that can cause
        stream eutrophication.
    • Seventy percent of the threatened and endangered vertebrates in Arizona depend on riparian areas. This relates directly to the Endangered Species Act (ESA) of 1973 (amended in 1988). The objective is to conserve threatened and endangered species and to monitor all listed species. Link to the ESA:
      http://www.fws.gov/endangered/esa.html, http://www.fws.gov/arizonaes/Threatened.htm (endangered and threatened species of AZ)
      Gila trout   


      Figure 1.8. Endangered species: Gila trout, Southwestern willow flycatcher and  Chiricahua Leopard Frog (Courtesy AZ Game and Fish, right).

    • Use for livestock production
      • Water
      • Forage
      • Shade
         
      Figure 1.9. Sheep and cows can graze riparian areas
    • Recreational activities that take place in riparian areas include: hiking, horse-back riding, cycling, fishing, hunting, swimming, raft floating, boating, canoeing, bird & wildlife watching, picnicking, camping and off-road vehicular traveling like ATV’s.
  7. The great number of riparian users and diverse perception of the importance and proper use of riparian areas make managing riparian areas a priority with the potential for conflicts.
  8. Many estimate that 70-90% of riparian areas in the United States have been altered by human activities that include: construction of dams, agriculture, urbanization etc.