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Implications of grazing regimes on vegetation, invertebrates and livestock performance and following heather restoration on degraded heathland - BD5105

Extensively grazed heathlands in the uplands of the UK are internationally important for their biodiversity value and are a key resource in supporting upland farmland economies and providing ecosystem services. However, high stocking densities have resulted in semi-natural vegetation being overgrazed with a decline in dwarf shrub species such as heather and bilberry. Targets for the enhancement and maintenance of these habitats have been established within the UK Biodiversity Action Plan (BAP) and options have been introduced under Environmental Stewardship for maintenance and restoration of heather moorland. To assist in the formulation of suitable guidelines for these options, there is a need to identify appropriate grazing regimes and other techniques to restore degraded dwarf shrub heathland, whilst maintaining acceptable levels of livestock performance and benefiting the wider moorland biodiversity.
Under previous Defra projects BD1228 and BD1243, system scale studies of sheep and cattle grazing and plot-scale restoration experiments were set up on degraded mat-grass moorland at ADAS Pwllpeiran from 2002 to 2010. Four grazing treatments were applied in replicated paddocks. These were sheep only at 1.0 ewes per ha and 1.5 ewes per ha, cattle only at 0.5 heifers per ha for two months in summer and mixed grazing (1.0 ewes per ha plus 0.5 heifers per ha in summer). Overall, performance of both sheep and cattle was adequate for commercial application in all treatments but the different grazing regimes showed varying benefits for biodiversity. For example, cattle were beneficial because they grazed bilberry less than sheep and reduced the competitive purple moor-grass, but numbers of several invertebrate groups (including some that are important in the diet of moorland birds) were reduced under cattle grazing treatments. Modelling outputs from project BD1228 also suggested that rotational or ‘pulsed’ grazing available as an option under Environmental Stewardship (whereby livestock are removed for one or more years before being reintroduced) had potential for restoration of heathland vegetation.
The plot-scale restoration experiments showed that the best grazing regimes to re-establish heather were seed addition plus disturbance, and either no grazing or cattle-only grazing. However, although Environmental Stewardship allows exclusion of livestock in heather restoration schemes, livestock will need to be re-introduced after initial establishment of heather to maintain the economic viability of moorland management. Currently, it is not known how newly-established heather and other vegetation will respond when grazing recommences. In restoration schemes where livestock exclusion is not practical, it will also be necessary to know the long-term responses under different grazing regimes.
Following a period of two years without grazing (2011 and 2012), the aim of this project is to re-introduce the grazing regimes at Pwllpeiran in 2013 and apply them for a further 3 years (4 years in total) to determine the long-term effects of ‘pulsed’ grazing by sheep and cattle on vegetation, invertebrates and livestock performance, and on heather established in the plot-scale restoration experiments. The restoration experiments will also be used to determine the effects of re-introducing grazing on heather that was established initially under a no-grazing regime.

The objectives of this project are to:

1. Reintroduce the grazing regimes on the 12 replicated treatment paddocks in 2013 and continue for a further 3 years (4 years in total).
2. Measure impacts on livestock performance under the different grazing regimes.
3. Repeat vegetation assessments in 2012 and 2016, to identify long-term effects of the different grazing regimes at the paddock scale, following a 2-year period where grazing was excluded.
4. Repeat invertebrate sampling in 2016, to identify long-term effects of the different grazing regimes.
5. Introduce grazing to a subset of the heather restoration plots not grazed since the start of the experiment, and repeat heather assessments in 2012 and 2016 under the different grazing regimes.
Project Documents
• EVID4 - Final project report : BD5105 Implications or grazing regimes Final Evidence report   (863k)
• ANX - Annex : BD5105 Implications of grazing regimes Appendix 1   (398k)
• ANX - Annex : BD5105 Implications of grazing regimes Appendix 2   (851k)
Time-Scale and Cost
From: 2012

To: 2017

Cost: £195,762
Contractor / Funded Organisations
Environmental Stewardship