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Individual study: Grazing Vertebrates Promote Invasive Swamp Stonecrop (Crassula helmsii) Abundance

Published source details

Dean C.E., Day J., Gozlan R.E. & Diaz A. (2015) Grazing Vertebrates Promote Invasive Swamp Stonecrop (Crassula helmsii) Abundance. Invasive Plant Science and Management, 8, 131-138


This study is summarised as evidence for the intervention(s) shown on the right. The icon shows which synopsis it is relevant to.

Crassula helmsii: Use grazing to control plants Control of Freshwater Invasive Species

A replicated, controlled study in 2012–2013 on the margins of a lake in Cambridgeshire, UK (Dean et al. 2015) found that excluding grazing reduced the abundance of C. helmsii compared to grazed plots. Cover of C. helmsii in ungrazed plots decreased from approximately 95% to 60% between July 2012 and October 2013, but remained above 90% in grazed plots. The abundance and diversity of other plants was higher in ungrazed compared to grazed plots (average abundance: 97% vs 38% cover respectively; mean species diversity (Shannon-Weiner): 1.1 vs 0.88). C. helmsii also had lower proportional abundance in ungrazed compared to grazed plots (approximately 47% of total vegetation abundance vs 74%). Six 4 m2 ungrazed fenced exclosures, interspersed with six 2 m2 grazed plots, were set up in February 2012. The area was grazed by sheep in January-March 2012 and August 2012-October 2013, and by buffalo in July-December 2012. Percentage cover of C. helmsii and other plants was estimated eight times between July 2012 and October 2013.