, Volume 156, Issue 4, pp 825–834 | Cite as

Spatial heterogeneity and plant species richness at different spatial scales under rabbit grazing

  • J. Olofsson
  • C. de Mazancourt
  • M. J. Crawley
Plant-Animal Interactions - Original Paper


Herbivores influence spatial heterogeneity in soil resources and vegetation in ecosystems. Despite increasing recognition that spatial heterogeneity can drive species richness at different spatial scales, few studies have quantified the effect of grazing on spatial heterogeneity and species richness simultaneously. Here we document both these variables in a rabbit-grazed grassland. We measured mean values and spatial patterns of grazing intensity, rabbit droppings, plant height, plant biomass, soil water content, ammonia and nitrate in sites grazed by rabbits and in matched, ungrazed exclosures in a grassland in southern England. Plant species richness was recorded at spatial scales ranging between 0.0001 and 150 m2. Grazing reduced plant height and plant biomass but increased levels of ammonia and nitrate in the soil. Spatial statistics revealed that rabbit-grazed sites consisted of a mixture of heavily grazed patches with low vegetation and nutrient-rich soils (lawns) surrounded by patches of high vegetation with nutrient-poor soils (tussocks). The mean patch size (range) in the grazed controls was 2.1 ± 0.3 m for vegetation height, 3.8 ± 1.8 m for soil water content and 2.8 ± 0.9 m for ammonia. This is in line with the patch sizes of grazing (2.4 ± 0.5 m) and dropping deposition (3.7 ± 0.6 m) by rabbits. In contrast, patchiness in the ungrazed exclosures had a larger patch size and was not present for all variables. Rabbit grazing increased plant species richness at all spatial scales. Species richness was negatively correlated with plant height, but positively correlated to the coefficient of variation of plant height at all plot sizes. Species richness in large plots (<25 m2) was also correlated to patch size. This study indicates that the abundance of strong competitors and the nutrient availability in the soil, as well as the heterogeneity and spatial pattern of these factors may influence species richness, but the importance of these factors can differ across spatial scales.


Spatial heterogeneity Species richness Herbivory Rabbit grazing 



The work was funded by The Swedish Research Council for Environment, Agricultural Sciences and Spatial Planning and the Swedish Foundation for International Cooperation in Research and Higher Education. The rabbit exclosures are part of a network of long-term field studies in Silwood Park maintained by the Division of Biology, Imperial College London.


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Copyright information

© Springer-Verlag 2008

Authors and Affiliations

  • J. Olofsson
    • 1
    • 2
  • C. de Mazancourt
    • 1
    • 3
  • M. J. Crawley
    • 1
  1. 1.Division of BiologyImperial College LondonAscotUK
  2. 2.Department of Ecology and Environmental ScienceUmeå UniversityUmeåSweden
  3. 3.Redpath MuseumMcGill UniversityMontrealCanada

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