Both bottom-up and top-down processes contribute to plant diversity maintenance in an edaphically heterogeneous ecosystem

Published source details Denyer J.L., Hartley S.E. & John E.A. (2010) Both bottom-up and top-down processes contribute to plant diversity maintenance in an edaphically heterogeneous ecosystem. Journal of Ecology, 98, 498-508.
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This study is summarised as evidence for the following.

	Action	Category
	Use fences to exclude livestock from shrublands Action Link

Use fences to exclude livestock from shrublands

A randomized, replicated, paired, controlled study in 1997–2003 in a heathland site in the UK (Denyer et al. 2010) found that fencing to exclude livestock increased vegetation height and biomass, but had a mixed effect on the number of plant species. After six years and in five of six comparisons, vegetation was taller in fenced areas (32–137 cm) than in unfenced areas (4–16 cm). Plant biomass was higher in fenced areas (1352–2832 g/m²) than in unfenced areas (751 g/m²). In one of two comparisons the number of plant species in fenced areas was lower (9 species) than in unfenced areas (17 species) but in one of two comparisons there was no significant difference in the number of plant species (fenced: 16 species, unfenced 17 species). The site was grazed by approximately 20 sheep throughout the study. Twenty four 4 x 4 m plots that were fenced to exclude livestock were established at the site, along with 12 unfenced plots. Half of the fenced plots could be accessed by rabbits that were present at the site. All plots were paired. In 2003 vegetation height was measured in each plot using a ruler and vegetation was harvested from subplots adjacent to plots to calculate biomass. Vegetation cover of all plant species was recorded in plots 2003.

(Summarised by: Phil Martin)