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Chapter 7: Human Alterations to Riparian Areas
Domestic Livestock
- Domestic livestock grazing is one of the most traditional land-use practices in riparian areas in the Southwest.
- Even today ranching still accounts for a significant portion of the agricultural economy of Arizona.
- The number of animals and period of time they graze the rangeland can lead to different impacts on riparian areas.
- The proper number of livestock will depend on the potential and resiliency of the riparian area.
- Most problems will occur with overgrazing.
- The timing and intensity of livestock grazing, as well as the opportunity for plant regrowth are important factors when making management decisions about grazing in riparian pastures.
- The timing should consider both the season of use and the length of time spent in the pasture.
- Excess vegetation removal (overgrazing) can also have indirect impacts such as:
- alteration of nutrient distribution in the soils, and
- give a competitive edge to exotics that are typically unpalatable to livestock.
- Trampling can increase soil compaction leading to:
- reduced infiltration and therefore increased runoff and sediment yield, and
- reduced root growth and subsequently plant growth.
- Reducing stream bank vegetative cover and trampling can increase stream bank erosion potential.
- In Arizona the biggest problem today is not the number of cattle, but improper distribution.
- Cattle tend to be attracted to riparian areas because of:
- water,
- favorable summer temperatures (shade),
- moderate terrain, and
- abundant forage.
Figure 7.11. Cattle in riparian areas of Arizona.
- Some BMP’s for livestock grazing include: seasonal use of pastures, rotating pastures, using alternate water sources, etc.
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