Study

Effects of Cattle Grazing on Diversity in Ephemeral Wetlands

Actions

This study is summarised as evidence for the following.

Action Category

Water: Use seasonal grazing

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Mediterranean Farmland

Water: Exclude grazers

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Mediterranean Farmland

Other biodiversity: Use seasonal grazing

Action Link
Mediterranean Farmland

Other biodiversity: Exclude grazers

Action Link
Mediterranean Farmland
  1. Water: Use seasonal grazing

    A replicated, randomized, controlled study in 2000–2003 in wet alpine meadows in central California, USA, found that pools in continuously grazed plots were wet for longer and dried out less frequently than those in seasonally grazed plots. Water availability: The maximum time that pools were wet was higher in continuously grazed plots, compared to seasonally grazed plots (115 vs 65–78 days). During a particularly dry year, pools in continuously grazed plots dried less frequently than those in seasonally grazed plots (1 vs 2 drying episodes).  Methods: Eighteen plots were established in 2000, each with three pools (70–1,130 m2) and nine times more dry land than pool. Areas were either grazed continuously or seasonally (dry: October–November; wet: April–June). Before the experiment, the area had been grazed for at least 100 years.

     

  2. Water: Exclude grazers

    A replicated, randomized, controlled study in 2000–2003 in wet in alpine meadows in central California, USA (same study as (5)), found that pools in plots from which cattle were excluded were wet for less time than those with two of three grazing regimes, and they dried more frequently than those in plots with one of three grazing regimes. Water availability: The maximum time that pools were wet was lower in ungrazed plots, compared to grazed plots, for two of three grazing regimes (65 vs 78–115 days), but not compared to plots that were grazed in the wet season. During a particularly dry year, pools in ungrazed plots dried more frequently than those in continuously-grazed plots, but not seasonally-grazed plots (2 vs 1 drying episodes). Methods: Eighteen plots were established in 2000, each with three pools (70–1,130 m2) and nine times more dry land than pool. Areas were grazed continuously or seasonally (dry: October–November; wet: April–June). Before the experiment, the area had been grazed for at least 100 years.

     

  3. Other biodiversity: Use seasonal grazing

    A replicated, randomized, controlled before-and-after study in 2000–2003 in wet grassland in central California, USA, found that the number of aquatic invertebrate species and native plant species, and the cover of native and exotic plants, varied between plots grazed at different times, in some comparisons. Invertebrates: There were more aquatic invertebrate species in pools in continuously-grazed plots, compared to seasonally-grazed plots, in one of three years (14 vs 11–12 species). Plants: The number of native plant species in pool edges declined more in 2001–2003 in wet-season grazed, compared to continuously or dry-season grazed plots (pool edges: 0.5 fewer species vs 1–1.8 more species). Changes within pools and on the surrounding dry land did not differ between plots with different grazing timings. There was a higher relative cover of native species in pool edges and surrounding dry land in continuously grazed plots, compared to seasonally grazed plots (pool edges: 72% vs 53–58%; dry land: 31% vs 17–18%). There was no difference in relative coverage of native species within pools between grazing timings. There was lower cover of exotic grasses in continuously grazed plots compared to dry- and wet-season grazed plots in dry land but not in other habitats (52% vs 69–84%). Methods: Eighteen plots were established in 2000, each with three pools (70–1,130 m2) and nine times more dry land than pool. Areas were grazed continuously or seasonally (dry-season: October–November; wet-season: April–June). Before the experiment, the area had been grazed for at least 100 years.

     

  4. Other biodiversity: Exclude grazers

    A replicated, randomized, controlled, before-and-after study in 2000–2003 in wet alpine meadows in central California, USA (same study as (22)), found fewer aquatic invertebrate species, and greater declines in the number of native plant species, in plots from which cattle were excluded, compared to grazed plots. Lower native-plant cover and higher exotic-grass cover was found in ungrazed plots, compared to grazed plots. Invertebrates: There were fewer aquatic invertebrate species in pools in ungrazed plots, compared to pools in grazed plots, in one of three years (10 vs 11–14 species). Plants: The number of native plant species in pool edges and surrounding dry land declined more in 2001–2003 in ungrazed plots, compared to grazed plots (pool edges: 1.3 fewer species vs 0.5 fewer to 1.8 more species; dry land: 0.5 fewer vs 1–1.2 more). Changes within pools did not differ between ungrazed and grazed plots. There was lower relative cover of native species in pool edges and surrounding dry land in ungrazed plots, compared to grazed plots (pool edges: 40% vs 54–72; dry land: 13 vs 18–31). There was no difference in relative cover of native species within pools between ungrazed and grazed plots. There was higher cover of exotic grasses in ungrazed and dry-season-grazed plots, compared to continuously-grazed and wet-season-grazed plots (84–86% vs 52–70%). Methods: Twenty-four plots were established in 2000, each with three pools (70–1,130 m2) and nine times more dry land than pool. Areas were either continuously or seasonally grazed by cattle (dry season: October–November; wet season: April–June), or grazers were excluded. Before the experiment, the area had been grazed for at least 100 years.

     

Output references

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