Control of Molinia caerulea on upland moors

Abstract

Summary 1.Molinia encroachment has been viewed as a major threat to moorland conservation in the UK and elsewhere in Europe. In England and Wales agri-environment schemes are in place that aim to reduce Molinia caerulea and encourage the development of dwarf shrub vegetation. We tested a range of management treatments to achieve these objectives in two regions (the North Peaks and Yorkshire Dales) in England. 2. Within each region, the same experiment was carried out on two types of moorland vegetation, Molinia -dominated 'white' moorland and a mixture of Molinia and Calluna vulgaris 'grey' moorland. Burning, grazing and herbicide (glyphosate) treatments were applied in factorial combination at each of the four sites (two regions × two moor types). The responses of both vegetation and individual species were assessed. In addition, on the white moors two techniques for Calluna re-establishment were investigated, (i) removal of Molinia litter by raking and (ii) application of Calluna seed. 3. The data were analysed using a combination of univariate and multivariate analysis of variance to identify trends in this complex data set. 4. The only treatment that had consistent effects in the univariate analysis of variance was glyphosate application, which had similar effects on Molinia at all study sites. There was little difference between the use of low and high application rates (0·27 and 0·54 kg ai ha). There was little impact of herbicide use on other moorland species. Some species were affected on some sites in some years, but there were no consistent effects. Tentative identification of species that responded positively, negatively and erratically to glyphosate application was made. 5. Greater Calluna seedling densities were found in the plots where herbicide was applied, the Molinia litter was removed and seed was added. However, after initial colonization, there was a reduction in Calluna seedling densities as the Molinia recovered. This indicated that disturbance, seed addition and follow-up management are required for successful Calluna establishment. 6. There were significant differences in community response between both the regions and moorland types. The Dales had a relatively greater contribution of grassland species than the Peaks, where the grey site had a relatively greater dwarf shrub component. 7. Burning had little effect on community composition but both grazing and herbicide application had important effects. Grazing of the grey sites, even at the very low levels used in this study, tended to push the communities towards bog-moorland vegetation, but little effect was found at the white sites. Glyphosate treatment tended to push communities towards acidic grassland at the Dales grey site but not at the Peaks. Successional change was also noted, with marked change between the third and fourth year and again between the fifth and six year. Grey sites showed the greatest temporal change. 8. Synthesis and applications . In terms of Molinia control and subsequent restoration of dwarf shrubs, there was...

Influence of livestock grazing on meadow pipit foraging behaviour in upland grassland

“…Over recent decades, substantial increases in Molinia, at the expense of dwarf shrub vegetation, have been observed in Europe (e.g. UK, Holland) due to inappropriate burning and grazing regimes (Marrs, Philips, Todd, Ghorbani, & Le Duc 2004). The utilisation of Molinia by livestock, in particular by cattle which are less selective than sheep, increases plant diversity (Grant et al 1996) and consequently habitat quality for insectivorous birds.…”

Changes in vegetation diversity and composition following livestock removal along an upland elevational gradient

“…Keywords: Calluna vulgaris, Community Change, Grazing, Heathland, Moorland, Restoration, Scotland community composition (Rawes 1981, Welch & Scott 1995, Bullock & Pakeman 1997, Marrs et al 2004. These have allowed authors to examine the extent to which general patterns can be discerned in post-restoration vegetation development, but untangling the effects of site-to-site differences in management history, vegetation, climate and soil type can still be difficult.…”

“…In many cases the removal or reduction of grazing by sheep has allowed Calluna to re-establish its dominance (Hulme et al 2002, Pakeman et al 2003, Fraser et al 2011, Critchley et al 2013) but this has certainly not been true everywhere (Rawes 1981, Littlewood et al 2006, and success thus requires that Calluna be present in the pre-restoration vegetation. On M. caerulea or N. stricta dominated sites success in the restoration of Callunadominated communities has generally been associated with cattle grazing, ground disturbance by trampling or rotavation, herbicide application and reseeding (Marrs et al 2004, Littlewood et al 2006, Mitchell et al 2008). However, long-term studies suggest that sites that have received minimal levels of disturbance during restoration (i.e., removal of grazing alone) tend to move closer to target conditions (Littlewood et al 2014).…”

“…Degraded heathlands are often dominated by competitive grass species such as Molinia caerulea (purple moor grass) and Nardus stricta (moor matgrass). Both of these can attain high levels of abundance, lead to communities with relatively low levels of diversity and can pose significant challenges for restoration practice (Grant et al 1996, Marrs et al 2004. A number of studies have examined the effects of grazing regimes on heathland communities, often concluding that restoration prescriptions need to be sitespecific.…”

“…For example, whilst it has proved possible to facilitate heathland recovery by simply reducing grazing pressure (Anderson & Radford 1994, Hulme et al 1999, Hulme et al 2002, often it has taken additional interventions to allow Calluna establishment. Successful treatments have included soil disturbance by cattle trampling, rotavation, herbicide application and reseeding (Marrs et al 2004, Mitchell et al 2008) and, where nutrient enrichment is an issue, topsoil removal (Verhagen et al 2001). Such intensive restoration actions may require managers to make difficult trade-offs as they may maximize Calluna cover but can also lead to the loss of other components of the community (Littlewood et al 2006).…”