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Providing evidence to improve practice

Individual study: Burning, grazing and herbicide control of purple moor-grass Molinia caerulea on moorland in the Yorkshire Dales and Peak District, England

Published source details

Marrs R.H., Phillips J.D.P., Todd P.A., Ghorbani J. & Le Duc M.G. (2004) Control of Molinia caerulea on upland moors. Journal of Applied Ecology, 41, 398-411


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

Use prescribed burning to control grass Shrubland and Heathland Conservation

A randomized, replicated, controlled study in 1995–2000 in four moorland sites in the UK (Marrs et al. 2004) found that prescribed burning to reduce the cover of purple moor grass Molinia caerulea initially reduced vegetation height, but this subsequently recovered. Immediately after prescribed burning vegetation height was lower in burned plots than in unburned plots, however after five years there was no longer a difference in height between burned and unburned plots (no data reported). In 1995 two blocks were established on each site and half of each block was burned. Fencing was established to limit grazing in two plots within each burned area but one plot was left unfenced. Within each plot the herbicide glyphosate was applied in two subplots and one subplot was not sprayed. Vegetation height was measured in 20 random locations with a sward stick in each plot.

(Summarised by Phil Martin)

Use herbicide to control grass Shrubland and Heathland Conservation

A randomized, replicated, controlled study in 1995–2000 in four moorland sites in the UK (Marrs et al. 2004) found that applying herbicide reduced the cover of purple moor grass Molinia caerulea as well as cover of the three plant species, increased the cover of four plant species, and had mixed effects on the cover of six other plant species. In five of five years, areas where herbicide was used had a lower cover of purple moor grass (9-32%) than areas where herbicide was not applied (40-45%). The cover of common heather Calluna vulgaris, crowberry Empetrum nigrum, bilberry Vaccinium myrtillus was lower in areas where herbicide was applied than in areas where it was not applied (no data reported). The cover of cross-leaved heath Erica tetralix, Juncus squarrosus, Polytrichum commune, sphagnum spp. was higher in areas where herbicide was applied than in areas where it was not applied (no data reported). Application of herbicide had an inconsistent effect on the cover of sweet vernal grass Anthoxanthum odouratum, wavy-hair grass Deschampsia flexuosa, common cottongrass Eriophorum angustifolium, Eriophorum vaginatum, deergrass Trichophorum cespitosum and bog cranberry Vaccinium oxycoccus (no data reported). In 1995 two blocks were established on each site and half of each block was burned. Fencing was established to limit grazing in two plots within each burned area but one plot was left unfenced. Within each plot glyphosate herbicide was applied in two subplots and one subplot was not sprayed. Cover of each species was estimated in four 1 m2 quadrats which were randomly placed in each plot.

(Summarised by Phil Martin)