Assessing changes in the agricultural productivity of upland systems in the light of peatland restoration Volume 1 of 1 Submitted by Guy William Freeman, to the University of Exeter as a thesis for the degree of Doctor of Philosophy in Biological Sciences, June 2017. This thesis is available for Library use on the understanding that it is copyright material and that no quotation from the thesis may be published without proper acknowledgement. I certify that all material in this thesis which is not my own work has been identified and that no material has previously been submitted and approved for the award of a degree by this or any other University. (Signature) ……………………………………………………………………………… 1 Thesis abstract Human activity has had a profound negative impact on the structure and function of the earth’s ecosystems. However, with a growing awareness of the value of the services provided by intact ecosystems, restoration of degraded land is increasingly used as a means of reviving ecosystem function. Upland landscapes offer an excellent example of an environment heavily modified by human land use. Agriculture has been the key driver of ecosystem change, but as upland habitats such as peatlands can provide a number of highly valuable services, future change may focus on restoration in order to regain key ecosystem processes. However, as pastoral farming continues to dominate upland areas, ecosystem restoration has the potential to conflict with existing land use. This thesis attempts to assess differences in the agricultural productivity of the different habitat types present in upland pastures. Past and present land use have shaped the distribution of different upland habitat types, and future changes associated with ecosystem restoration are likely to lead to further change in vegetation communities. Three key contributors to agricultural productivity are examined. Firstly, variation in the nutritional quality of different upland habitats is assessed, in order to understand their value for grazing animals. Secondly, levels of livestock use in different habitats are compared in order to identify areas of particular importance for grazing. Finally, parasite populations are measured in different habitats in order provide an indication of which habitats pose the greatest potential risk of infection.It is shown that these factors appear to differ between habitats, meaning that agricultural productivity may show spatial variation in upland pastures. However, it appears that peatland restoration might have a negligible impact on farming in upland pastures due to apparent minor differences in the agricultural productivity of the habitats most likely to be affected. 2 Table of contents Thesis abstract ......................................................................................................... 2 List of tables and figures ......................................................................................... 6 Author’s declaration .............................................................................................. 15 Definitions ............................................................................................................... 16 Chapter 1: Thesis introduction ............................................................................. 19 1.1 Drivers of and response to ecosystem change ........................................................................... 19 1.1.1 Background .......................................................................................................................... 19 1.1.2 Natural drivers of ecosystem change................................................................................... 20 1.1.3 Human drivers of ecosystem change: global biogeochemical cycles .................................. 21 1.1.4 Human drivers of ecosystem change: land modification..................................................... 23 1.1.5 Agriculture as a driver of ecosystem change ....................................................................... 25 1.2 Ecosystem services ...................................................................................................................... 28 1.2.1 The value of ecosystem services .......................................................................................... 28 1.2.2 Restoration ecology ............................................................................................................. 31 1.3 Ecosystem change in uplands ..................................................................................................... 33 1.3.1 Landscape change in UK uplands ......................................................................................... 33 1.3.2 Peatlands .............................................................................................................................. 37 1.4 Thesis outline .............................................................................................................................. 40 Chapter 2: Site descriptions and habitat mapping .............................................. 43 2.1 Exmoor ........................................................................................................................................ 43 2.1.1 Exmoor National Park .......................................................................................................... 43 2.1.2 Landscape change on Exmoor.............................................................................................. 44 2.1.3 Agriculture on Exmoor ......................................................................................................... 46 2.1.4 Exmoor peatlands ................................................................................................................ 46 2.2 Study sites ................................................................................................................................... 48 2.2.2 Habitat mapping .................................................................................................................. 54 2.3 Conclusion ................................................................................................................................... 57 Chapter 3: Sward quality in upland pastures ...................................................... 73 3.1 Background ................................................................................................................................. 73 3.1.1 The effects of ecosystem change on vegetation ................................................................. 73 3.1.2 Vegetation change in upland environments ........................................................................ 76 3 3.1.3 Peatland restoration and vegetation change ...................................................................... 78 3.1.4 Nutritional quality of plants ................................................................................................. 80 3.1.5 Nutritional quality of upland pastures ................................................................................. 83 3.1.6 Hypotheses........................................................................................................................... 85 3.2 Materials and methods ............................................................................................................... 85 3.2.1 Vegetation surveys ............................................................................................................... 86 3.2.2 Nutritional analysis .............................................................................................................. 89 3.2.3 Statistical analysis ................................................................................................................ 92 3.2.4 Mapping sward quality ........................................................................................................ 93 3.3 Results ....................................................................................................................................... 103 3.3.1 Nutritional quality of upland plants ................................................................................... 103 3.3.2 Nutritional quality of upland habitats ................................................................................ 104 3.4 Discussion .................................................................................................................................. 104 Chapter 4: Cattle grazing behaviour in upland pastures .................................. 112 4.1 Background ............................................................................................................................... 112 4.1.1 Ecosystem change and grazing .......................................................................................... 112 4.1.2 Habitat selection by large herbivores ................................................................................ 114 4.1.3 Grazing behaviour of cattle ................................................................................................ 117 4.1.4 Grazing in upland pastures ................................................................................................ 120 4.1.5 Hypotheses......................................................................................................................... 122 4.2 Materials and methods ............................................................................................................