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BMC ecology2009; 9; 22; doi: 10.1186/1472-6785-9-22

Impacts of feral horses on a desert environment.

Abstract: Free-ranging horses (Equus caballus) in North America are considered to be feral animals since they are descendents of non-native domestic horses introduced to the continent. We conducted a study in a southern California desert to understand how feral horse movements and horse feces impacted this arid ecosystem. We evaluated five parameters susceptible to horse trampling: soil strength, vegetation cover, percent of nonnative vegetation, plant species diversity, and macroinvertebrate abundance. We also tested whether or not plant cover and species diversity were affected by the presence of horse feces. Results: Horse trailing resulted in reduced vegetation cover, compacted soils, and in cases of intermediate intensity disturbance, increased plant species diversity. The presence of horse feces did not affect plant cover, but it did increase native plant diversity. Conclusions: Adverse impacts, such as soil compaction and increased erosion potential, were limited to established horse trails. In contrast, increased native plant diversity near trails and feces could be viewed as positive outcomes. Extensive trailing can result in a surprisingly large impact area: we estimate that 25 km2 of trails in our study area.
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Publication Date: 2009-11-10 PubMed ID: 19903355PubMed Central: PMC2781800DOI: 10.1186/1472-6785-9-22Google Scholar: Lookup
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  • Journal Article
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  • Non-U.S. Gov't

Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

The research observes the effects of feral horses on a desert environment in southern California, detailing how their movements and feces impact several aspects including soil strength, vegetation cover, plant species diversity, and macroinvertebrate abundance. The study found that while horse activity resulted in soil compaction and reduced vegetation cover, it also led unpredictably to increased plant species diversity, especially among native plants in the area.

Study Objective and Execution

  • The objective of this study was to investigate the impacts of feral horses on desert ecosystems in southern California, particularly focusing on the effects of horse movements and feces on soil and vegetation characteristics.
  • Five parameters were assessed to evaluate the impacts of horse trampling, including soil strength, the coverage of vegetation, the percentage of non-native vegetation, plant species diversity, and the abundance of macroinvertebrates.
  • The researchers also assessed whether the presence of horse feces affected plant cover and species diversity.

Findings

  • The research found that horse trailing – the process of horses moving through the environment – resulted in reduced vegetation cover, compacted soils, and interestingly, where the disturbance was of an intermediate intensity, an increase in plant species diversity.
  • Despite initial assumptions, the presence of horse feces did not affect plant coverage, but it did contribute to an increase in the diversity of native plants.
  • It was also discovered that the negative impacts, such as soil compaction and increased potential for erosion, were generally localized around established horse trails, rather than evenly distributed across the environment.

Conclusions

  • The influence of horse activity tends to see adverse effect confined to established horse trails. However, it also leads to unpredictable positive outcomes, such as the increase in native plant diversity near trails and feces.
  • Considering the possible scale of the impact area, even a relatively small number of horses can significantly affect a large area of land. The study estimated that less than 30 horses used more than 25 km2 of trails in the study area, demonstrating the landscape-scale impact that feral horses can have.

Cite This Article

APA
Ostermann-Kelm SD, Atwill EA, Rubin ES, Hendrickson LE, Boyce WM. (2009). Impacts of feral horses on a desert environment. BMC Ecol, 9, 22. https://doi.org/10.1186/1472-6785-9-22

Publication

BMC ecology
ISSN: 1472-6785
NlmUniqueID: 101088674
Country: England
Language: English
Volume: 9
Pages: 22

Researcher Affiliations

Ostermann-Kelm, Stacey D
  • Wildlife Health Center, University of California, Davis, CA 95616, USA.Stacey_ostermann-kelm@nps.gov
Atwill, Edward A
    Rubin, Esther S
      Hendrickson, Larry E
        Boyce, Walter M

          MeSH Terms

          • Animals
          • California
          • Desert Climate
          • Ecosystem
          • Feces / chemistry
          • Horses / physiology
          • Plant Development
          • Soil / analysis

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          Citations

          This article has been cited 4 times.
          1. Watson VT, Kehler D, Medeiros AS. A paleolimnological context of ecological vulnerability for the freshwater ecosystems of Sable Island National Park Reserve, Canada. Sci Prog 2022 Oct-Dec;105(4):368504221126865.
            doi: 10.1177/00368504221126865pubmed: 36254564google scholar: lookup
          2. Lönker NS, Fechner K, Wahed AAE. Horses as a Crucial Part of One Health. Vet Sci 2020 Feb 29;7(1).
            doi: 10.3390/vetsci7010028pubmed: 32121327google scholar: lookup
          3. Naundrup PJ, Svenning JC. A Geographic Assessment of the Global Scope for Rewilding with Wild-Living Horses (Equus ferus). PLoS One 2015;10(7):e0132359.
            doi: 10.1371/journal.pone.0132359pubmed: 26177104google scholar: lookup
          4. White SC, Thomas J, Shores C, Zimmerman K. Where Dinner Roams: The Role of Feral Horses as a Resource Subsidy for Wolves and Cougars in West-Central British Columbia. Ecol Evol 2026 Feb;16(2):e73089.
            doi: 10.1002/ece3.73089pubmed: 41684831google scholar: lookup
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