Report Number 648 Large herbivores in the wildwood and in modern naturalistic grazing systems English Nature Research Reports working today for nature tomorrow English Nature Research Reports Number 648 Large herbivores in the wildwood and modern naturalistic grazing systems K H Hodder1, J M Bullock1, P C Buckland2, & K J Kirby3 1Centre for Ecology and Hydrology, Dorset 2 School of Conservation Sciences, Bournemouth University/ECUS 3 English Nature, Northminster House, Peterborough, PE1 1UA You may reproduce as many additional copies of this report as you like, provided such copies stipulate that copyright remains with English Nature, Northminster House, Peterborough PE1 1UA ISSN 0967-876X © Copyright English Nature 2005 ‘…let us again recur to Nature. The process by which she forms woods and forests is as follows. Seeds are scattered indiscriminately by winds, brought by waters and dropped by birds. They perish, or produce, according as the soil and situation upon which they fall are suited to them: and under the same dependence, the seedling or sucker, if not cropped by animals (which Nature is often careful to prevent by fencing it about with brambles or other prickly shrubs) thrives, and the tree grows, sometimes single, taking its own shape without constraint, but for the most part compelled to conform itself to some law imposed upon it by its neighbours.’ William Wordsworth, 1835, A guide through the District of the Lakes “The beautiful British countryside ….. is maintained by farming and other land management practices. Without dedicated work the countryside would degenerate into scrub, even threatening the survival of those species that depend on cultivation or grazing and obscuring beautiful views and archaeological features”. Times (letters) 2/4/05, p24. Preface This report stems from work commissioned by English Nature into the role of large herbivores in the post-glacial landscape of Britain and the potential for using free-ranging grazing animals to create and maintain diverse landscape mosaics in modern conditions. Some aspects may be disputed or considered controversial; it is an active field of research. Therefore we stress that the views expressed are those of the authors at the current time. Subsequent research may confirm our views or lead us to modify them. We hope they will be useful in future discussions, both within English Nature and in conservation land-management circles more generally. Keith Kirby English Nature, Northminster House, Peterborough, PE1 1UA May 2005. Acknowledgements Drafts of this review were circulated widely and we are very grateful to all the people who provided comment, material for inclusion and valuable discussion - especially Frans Vera, Toby Aykroyd, Keith Alexander, Isabel Alonso, Helen Armstrong, Steve Aylward, John Bacon, Keith Barber, Jan Bakker, Fred Baerselman, Jan Bokdam, Richard Bradshaw, Gareth Browing, Philip Buckland, Erik Buchvald, David Bullock, Charlie Burrell, Adam Burrows, Jill Butler, Steve Clark, Michael Clarke, Rob Cooke, Tim Darvill, Richard Davis, Mark Dinnin, Chris Edwards, Jason Emrich, James Fenton, David Foster, Nick Gibbons, Robin Gill, Francois Gillet, Michael Grant, Ted Green, James Grieg, Jeannette Hall, Steven Hall, Paul Harding, Mark Hill, Kate Holl, Damian Hughes, Richard Jefferson, Barbara Jones, Hans Kampf, Francis Kirkham, Sophie Lake, Stewart Lane, Jim Latham, Rod Leslie, Neil Lister, Rob Lucking, Richard Luxmore, Rob Macklin, Peter Marks, Mel Kemp, Fraser Mitchell, Ed Mountford, Andy Needle, Matthew Oates, Eva Panagiotakopulu, George Peterken, Feiko Prins, Richard Rafe, Mark Robinson, Francis Rose, Jon Sadler, Neil Sanderson, Henk Siebel, David Smith, Mike smith, Christopher Smout, Mary-Ann Smyth, Jonathon Spencer, David Stevens, Jerry Tallowin, Peter Taylor, Chris Thomas, Richard Tipping, Sandie Tolhurst, Keith Turner, Michiel Wallis de Vries, Lena Ward, Peter Quelch, Saskia Wessels, Tony Whitbread, Nicki Whitehouse, Robert Wolton and Derek Yalden, Rachel Yanik. Apologies if there is anyone we have missed out. Special thanks to Rebecca Isted, Andy Wagstaff and David Storey who ran the contract and to Mary Roberts and her team who worked their way through the various drafts. Summary English Nature’s interest in the role of large herbivores in forest systems K.J.Kirby • Frans Vera’s book Grazing Ecology and Forest History challenges our views on the nature of the former natural landscape in Britain. English Nature therefore commissioned a review of the nature and current state of the debate on his hypothesis and its relevance to future conservation practice. • Understanding the role of grazing in past forests is relevant to current work on improving the management of wood-pasture systems, but also to proposals to encourage landscape-scale conservation programmes. • Debates about Vera’s hypothesis have however been hampered by different interpretations of the words used to describe wooded and unwooded landscapes; and different ‘visions’ of what sort of landscape the Vera hypothesis or its alternatives might produce. • Two separate questions need to be addressed: (i) were large herbivores the main drivers of the landscape, and, if so, (ii) did they produce half-open landscapes? The Vera model of post-glacial landscapes in Europe: a summary of the debate K.H. Hodder & J.M. Bullock • Responses to the ideas put forward in Frans Vera’s book Grazing History and Forest Ecology are summarised. • Vera argues that, if the natural forest (before significant human impact) is assumed to consist only of closed-canopy conditions, then the light demanding species, oak and hazel, should not be so well represented in the fossil record. He uses ecological, palynological, etymological and historical arguments to propose a ‘half-open’ park-like landscape for the lowlands of Central and Western Europe in the pre-Neolithic, Atlantic era, c7,000 years ago. • There has been an enthusiastic welcome to the notion that wood pasture systems may be more representative of the original-natural landscape than closed high forest, and should therefore be given high conservation priority. However, the degree of landscape openness and the mechanisms by which clearings may be generated are the subject of much debate. Vera argues that large herbivores were an essential driving force behind the cyclical vegetation dynamics that resulted in shifting mosaic systems. Other authors suggest that abiotic disturbance such as fire and windthrow may also have important roles. • Reviewers accept that there can be considerable bias in interpretations of the fossil pollen record, but note that analyses based on combinations of pollen and macrofossil remains, which tend to lead to similar conclusions, can be much more robust. • Problems caused by the paucity of large mammal remains are harder to solve. In fact the debate about the scale and impacts of past ungulate-vegetation interactions is unlikely to be fully resolved until more is known about past ungulate population sizes. • The picture that emerges is one of a mixed landscape including areas with vegetation cycles and others with more permanent vegetation. The difference between the closed forest hypothesis and Vera’s alternative of cyclical dynamics may be a matter of degree. While there is general agreement that the original-natural forest may have been more open than was previously thought, this is not equivalent to saying that a wood-pasture landscape would necessarily dominate the landscape. The balance of opinion is towards predominance of closed forest with localised, longer lasting openings. Shifting vegetation mosaics may have operated on fertile floodplains, and open vegetation may have been frequent on floodplains, infertile soils, limestone and poor sandy soils. • One of the major problems involved in applying Vera’s ideas in conservation is that there is no clear idea of spatial or temporal scale. Degrees of openness are likely to vary in different soil and topographic (and climatic) conditions, but at present there is no guidance on the patterns that might be expected. Therefore, a key area for future research is to understand the factors influencing temporal and spatial patterns of the grassland-forest matrix in the full range of environmental conditions. Palaeoecological evidence for the Vera hypothesis P.C. Buckland • The model put forward by Frans Vera is examined in the light of the palaeoecological record for the Holocene and previous Late Quaternary interglacials. Previous reviews have largely dealt with the data available from pollen diagrams, and so this chapter concentrates upon the fossil beetle (Coleoptera) evidence, utilising the extensive database of Quaternary insect records, BUGS. • The insect record is much less complete than the pollen one, but there are clear indications of open ground taxa being present in the ‘Atlantic forest’. The extent of open ground and dung faunas during the Neolithic suggests that many of these elements were already present (although not necessarily abundant) in the natural landscape before agriculturalists began extensive clearance during the late sixth millennium BP. • In the palynological literature there is something of a dichotomy between those working in the uplands and lowlands, with the former being more inclined to credit Mesolithic hunter/gatherers with deliberate modification of the forest cover, usually utilising fire, sometimes leading to the expansion of blanket bog and in the lowlands the creation of heath. The concept of a natural forest, without human interference,