Effects of experimental disturbance on multi-taxa assemblages and traits: conservation implication in a forest-open landscape mosaic Scott M Pedley Thesis submitted for the degree of Doctor of Philosophy School of Environmental Sciences University of East Anglia, UK September 2012 This copy of the thesis has been supplied on condition that anyone who consults it is understood to recognise that its copyright rests with the author and that use of any information derived there from must be in accordance with current UK Copyright Law. In addition, any quotation or extract must include full attribution Contents Chapter 1 ....................................................................................................................... 11 1.1 Landscape connectivity ......................................................................................... 11 1.2 Plantation forestry ................................................................................................. 13 1.3 Study system ......................................................................................................... 15 1.3.1 Habitat ............................................................................................................ 15 1.3.2 Species ........................................................................................................... 16 1.3.3 Invertebrate surveying .................................................................................... 19 1.4 Thesis background ................................................................................................ 21 1.4.1 Thesis aims ..................................................................................................... 21 1.4.2 Contributions to the thesis .............................................................................. 21 1.4.3 Thesis structure .............................................................................................. 22 Chapter 2 ....................................................................................................................... 30 2.1 Introduction ........................................................................................................... 31 2.2 Methodology ......................................................................................................... 33 2.2.1 Study site ........................................................................................................ 33 2.2.2 Spider sampling in trackways ........................................................................ 34 2.2.3 Heathland sampling ........................................................................................ 37 2.2.4 Identification .................................................................................................. 37 2.2.5 Analysis .......................................................................................................... 39 2.3 Results ................................................................................................................... 41 2.3.1 Ground-active spider composition in Thetford Forest trackways .................. 42 2.3.2 Ground spider composition in heathland reference sites ............................... 42 2.3.3 Community composition of trackway and heathland reference assemblages 42 2.3.4 Community comparison: habitat association ................................................. 45 2.3.5 Influence of trackway width........................................................................... 45 2.4 Discussion ............................................................................................................. 49 2.4.1 Heathland spider communities in forestry trackways .................................... 49 2.4.2 Effects of forest growth stage on trackway assemblage ................................ 49 2.4.3 Influence of trackway width on the spider community .................................. 49 2.4.4 Connectivity and dispersal ............................................................................. 50 2.4.5 Management implications .............................................................................. 51 2.4.6 Conclusion ..................................................................................................... 52 Chapter 3 ....................................................................................................................... 56 3.1 Introduction ........................................................................................................... 57 2 3.2 Methodology ......................................................................................................... 59 3.2.1 Study site ........................................................................................................ 59 3.2.2 Physical disturbance treatments ..................................................................... 59 3.2.3 Invertebrate sampling in treatment plots ........................................................ 61 3.2.4 Invertebrate sampling in heath reference sites ............................................... 62 3.2.5 Plant species composition and vegetation structure ....................................... 62 3.2.6 Classification of species ................................................................................. 62 3.2.7 Data analysis .................................................................................................. 63 3.3 Results ................................................................................................................... 64 3.3.1 Vegetation structure ....................................................................................... 64 3.3.2 Composition of carabid assemblages ............................................................. 68 3.3.3 Composition of spider assemblages ............................................................... 68 3.3.4 Composition of ant assemblages .................................................................... 72 3.3.5 Composition of vascular plants ...................................................................... 72 3.4 Discussion ............................................................................................................. 72 3.4.1 Enhancing quality........................................................................................... 72 3.4.2 Contrasting taxonomic responses ................................................................... 73 3.4.3 Durability of treatment ................................................................................... 75 3.4.4 Conservation implications .............................................................................. 76 Chapter 4 ....................................................................................................................... 96 4.1 Introduction ........................................................................................................... 97 4.2 Methodology ....................................................................................................... 100 4.2.1 Study design ................................................................................................. 100 4.2.2 Sampling protocol ........................................................................................ 101 4.2.3 Species traits................................................................................................. 102 4.2.4 Environmental parameters ........................................................................... 104 4.2.5 Analysis ........................................................................................................ 104 4.3 Results ................................................................................................................. 106 4.3.1 Carabids ....................................................................................................... 106 4.3.2 Spiders .......................................................................................................... 110 4.3.3 Vascular plants ............................................................................................. 112 4.4 Discussion ........................................................................................................... 115 4.4.1 Mobility ........................................................................................................ 115 4.4.2 Size and phenology ...................................................................................... 117 4.4.3 Trophic guild ................................................................................................ 119 4.4.4 Rarity and distribution ................................................................................. 119 4.4.5 Conclusions .................................................................................................. 120 3 Chapter 5 ..................................................................................................................... 131 5.1 Introduction ......................................................................................................... 132 5.2 Methodology ....................................................................................................... 134 5.2.1 Study site and design .................................................................................... 134 5.2.2 Sampling ...................................................................................................... 135 5.2.3