Study

Loss of biodiversity and hydrologic function in seasonal wetlands persists over 10 years of livestock grazing removal

  • Published source details Marty J.T. (2015) Loss of biodiversity and hydrologic function in seasonal wetlands persists over 10 years of livestock grazing removal. Restoration Ecology, 23, 548-554

Actions

This study is summarised as evidence for the following.

Action Category

Water: Exclude grazers

Action Link
Mediterranean Farmland

Exclude or remove livestock from historically grazed freshwater marshes

Action Link
Marsh and Swamp Conservation

Other biodiversity: Exclude grazers

Action Link
Mediterranean Farmland
  1. Water: Exclude grazers

    A replicated, randomized, controlled study in 2002–2010 in central California, USA (same study as (2)), found that pools in plots from which cattle were excluded were shallower and wet for less time than those in grazed plots. Water availability: Pools were shallower in ungrazed plots, compared to grazed plots (8 vs 12 cm maximum depth), and were wet for fewer days each year (16–178 vs 41–192 wet days/year). Differences were more pronounced in drier years.  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. Pools were monitored in 2002–2010.

     

  2. Exclude or remove livestock from historically grazed freshwater marshes

    A replicated, randomized, paired, controlled study in 2000–2010 of ephemeral pools within a grassland in California, USA (Marty 2015) found that excluding cattle typically increased the dominance of grasses, but reduced the dominance and richness of native plants. In 5 of 10 years, pools fenced to exclude cattle had greater relative grass cover (1.2–4.8 times forb cover) than pools that remained grazed (0.2–1.7 times forb cover). In the other five years, there was no significant difference between exclusion and grazed pools. In 10 of 10 years, exclusion pools had lower relative cover of native plant species (0.3–0.6 times non-native cover) than grazed pools (0.5–0.7 times non-native cover). In 9 of 10 years, exclusion pools had lower native plant richness (5.8–6.8 species/0.25 m2) than grazed pools (8.0–9.0 species/0.25 m2). Methods: In 2000, six pairs of plots were established on a ranch grazed for >100 years. In each pair, one plot was fenced to exclude cattle whilst the other remained grazed (October–June; 1 cow-calf pair/2.4 ha). Each spring between 2001 and 2003, vegetation was surveyed in three dried-up pools (and adjacent upland) in each plot. Pools were 70–1,130 m2. Ungrazed pools were dry for longer than grazed pools. This study was based on the same experimental set-up as (2).

    (Summarised by: Nigel Taylor)

  3. Other biodiversity: Exclude grazers

    A replicated, randomized, controlled, before-and-after study in 2000–2010 in grasslands and wetlands in central California, USA (same study as (21)), found fewer species and lower cover of native plants in plots with cattle excluded, compared to grazed plots. Community composition differed, and biomass at the end of the summer was higher, in ungrazed plots, in some comparisons. Plants: Fewer native plant species were found in ungrazed plots, compared to cattle-grazed plots, in all but the first year of the experiment (6–8 vs 7–9 species/sample). Cover of native plant species was lower in ungrazed plots, compared to cattle grazed plots (32–61% vs 50–67%). This effect was stronger at pool edges than within pools or on dry land (lower native cover in four of 10 years for edges vs two of 10 years for other habitats). Ungrazed plots were more dominated by grasses in five of 10 years (0.7–4.6 vs 0.3–0.8 times more grass than non-grass cover). Ungrazed plots had higher plant biomass at the end of the grazing season, compared to grazed plots, in seven of 10 years (2,100–4,000 vs 860–2,200 kg dry mass/ha). Methods: Twenty-four plots were established in 2000, each with three pools (70–1,130 m2) and nine times more dry land than pool area. In 2000–2003, cattle were excluded from six pools, six were grazed continuously from October to June, and 12 were grazed seasonally (either October–January or April–June). In 2003, the seasonal grazing experiment was stopped and only ungrazed and continuously grazed plots were continued. Plants were monitored in April–May each year within pools, at pool edges, and on dry land. The area had been grazed for at least 100 years before the start of the experiment.

     

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