Managing Molinia? Proceedings of a 3-day conference 14-16 September 2015 in Huddersfield, West Yorkshire, UK. Edited by Roger Meade National Trust Molinia Conference organising committee at Marsden Moor Estate office. L-R: Alan Stopher, Craig Best, Roger Meade, Nick Pollett and Andrew Underdown. With assistance from Rob Henry, Alyssa Young and Frances DeGiorgio (not in picture). Cover image © Alan Stopher View towards Pule Hill north-eastwards from the route of the old turnpike. Redbrook reservoir is in the middle distance. This is one of the original canal reservoirs which is maintained by Canal & River Trust with the water supplying Yorkshire Water’s customers. A sailing club also uses the amenity. Molinia tussocks dominate the foreground. 2 ‘Managing Molinia’ Conference, 14-16 September 2015, Huddersfield, UK; National Trust, ed. R Meade To cut, or not to cut. A very straightforward question, but so much Foreword more succinct than the answer. This is the dilemma often faced by managers of land for nature conservation where the easiest solution is to just follow what others are doing. As a former habitat specialist for a statutory nature conservation body, I am familiar with the pressures to provide clear guidance and one I remember well is the popular belief that any trees on lowland raised bogs should be cut down and prevented from regrowth. While there is a case for adopting this principle in many situations there are those in which it is not necessary, and is even undesirable from other perspectives such as the trees’ contribution to the landscape. It means that the conservation land manager must not only be aware of the bare bones of the received wisdom, but also of the caveats that make it possible for him or her to arrive at a reasoned judgement for their specific situation. So it is for Molinia caerulea, the Purple Moor-grass. It is a widespread species, being part of a range of wetland and damp pasture plant communities, sometimes becoming dominant, in other situations adopting a more restrained role. There are instances where its ability to dominate does, in the opinion of conservation managers, detract from what constitutes ‘favourable condition’, the conclusion being that it should be removed and replaced with something more ‘natural’. This conference was conceived in a culture where some conservation managers feel they should go out and cut off the Molinia tussocks, in the hope of replacing them with something closer to the expectations of the statutory nature conservation organisation responsible for setting conservation objectives. This is the point at which resources can be consumed in the pursuit of a sometimes uncertain goal, again, carried out on the back of the received wisdom. There was, it seemed, a need for the providers of guidance to be clearer about their objectives and for the land managers, where cutting is appropriate, to be more aware of parallel work being done on Molinia management elsewhere to help target their resources efficiently. Volunteers and National Trust staff at the Marsden Moor Estate were of one mind in wanting to establish clarity in the perceptions of Molinia- dominated habitat in the uplands, particularly on peat. The idea was welcomed by Natural England, who, in conjunction with the International Peat Society (IPS), provided the financial backing for the event. The programme was designed to give as much theoretical background as possible within the available time and to exchange relevant land management experience. In addition to the sense of achievement arising from providing the event, the organisers feel that it would be an ample reward for their efforts if these Proceedings act as a benchmark for ongoing discussion of the subject, the development of concepts based Roger Meade Chair on science, and the sharing of land management experience. Molinia Conference The organisers would like to thank all the contributors for the high Organising Committee quality of their presentations and their patience in carrying out their (Craig Best, Rob Henry, ‘instructions’; also, all those attending, whose willingness to pitch into Roger Meade, Nick the discussions made the event, we believe, a great success. We are Pollett, Alan Stopher, Andrew Underdown, particularly grateful to Natural England and the IPS, without whose Alyssa Young, Frances support the event would not have taken place. For further information, DeGiorgio) please contact [email protected] 3 ‘Managing Molinia’ Conference, 14-16 September 2015, Huddersfield, UK; National Trust, ed. R Meade Contents Molinia in plant communities and the factors that influence its growth .............................................................10 Molinia caerulea Purple Moor-grass: Context for Management .......................................... 11 An introduction to its place in mire plant communities in England .................................... 11 Roger Meade Introduction ............................................................................................................................... 11 The distribution of Molinia caerulea in the British Isles .......................................................... 12 Molinia caerulea in plant communities ......................................................................................13 The status of Molinia-dominated blanket mire ...................................................................... 19 Palaeoenvironmental evidence for the recent rise of Molinia caerulea: vital information for conservation managers ....................................................................... 22 Frank M. Chambers and Julia McCarroll Introduction ..............................................................................................................................22 Rationale for collaborative studies ..........................................................................................23 Techniques ................................................................................................................................24 Example of some results...........................................................................................................25 Overall Results ..........................................................................................................................26 Introduction ..............................................................................................................................28 Air-borne pollution from past to present ...............................................................................28 The importance of atmospheric quality in determining upland vegetation ......................28 Simon JM Caporn et al. Recovery of Sphagnum and other bryophytes ......................................................................29 Factors limiting recovery of bog vegetation .......................................................................... 30 Impacts of nitrogen deposition on plant communities ..........................................................31 Exceedance of the nitrogen critical load .................................................................................32 Evidence for the role of nitrogen deposition in Molinia expansion .......................................33 Uncertain threats to upland vegetation – Ozone and Carbon dioxide ................................34 Summary ...................................................................................................................................35 Molinia – the importance of controlling water and other management techniques ......... 39 Penny Anderson Introduction ..............................................................................................................................39 Soils ............................................................................................................................................39 Vegetation communities ......................................................................................................... 40 Nutrient and eco-hydrological relationships ...........................................................................41 Other possible factors ............................................................................................................. 44 Conclusion ................................................................................................................................ 44 Why soils have dried out ......................................................................................................... 44 Overgrazing .........................................................................................................................49 Peat extraction ....................................................................................................................49 Controlling Molinia through re-wetting ..................................................................................49 Conclusions ...............................................................................................................................52 4 ‘Managing Molinia’ Conference, 14-16 September 2015, Huddersfield, UK; National Trust, ed. R Meade The place of Molinia in blanket mire and other upland peat habitats: defining what is ‘good’ ................................................55 Molinia caerulea in upland habitats: a Natural England perspective on the perceived issue of ‘over-dominance’ .........................................................................