Modelling forest landscape dynamics in Glen Affric, northern Scotland Joseph C. E. Hope Doctor of Philosophy University of Stirling 2003 ii Declaration I hereby confirm that the work contained in this thesis is my own except where assistance is acknowledged. -- iii Acknowledgements The project documented by this thesis was funded entirely by the Forestry Commission; for this assistance, I am most grateful. I would like to also acknowledge the help of a great many people – more than it is possible to mention by name – who have made the completion of this work possible, and at times even enjoyable. These include many of the staff and students at the Department of Environmental Sciences, University of Stirling; Forest Research, Northern Research Station and Forest Enterprise, Fort Augustus. Of course, I must pick out my supervisors, Patrick Osborne and Richard Tipping for particular recognition. Their support and comments on earlier drafts of chapters have been invaluable. To my advisors, Jonathan Humphrey and Chris Quine, I owe a most extraordinary debt of thanks, not only for scientific advice and discussions but also for their constant encouragement. On more than a few occasions they have saved me from despair! The examiners, Andrew Fall and John Proctor gave good battle in the viva and I must further acknowledge Andrew for his help in using the SELES program, which effectively turned the fortune of this project around. The following fine people also deserve special recognition for their contributions, witting or otherwise: Helen Armstrong, Alice Broome, Simon Bell, Christine Cahalan, Jean Campbell, Tim Clifford, Brian and Sandy Coppins, Colin Edwards, Kate Fielding, Duncan Golicher, Stuart Heritage, Jason Hubert, Adrian Newton, Duncan Ray, Lorna Raso, Louise Ross, Richard Thompson, Liesbeth van der Sluijs, Jim Wright, Caroline Younger. Finally, a monster thank you to Guy Bolton King and Judi Oates who helped so much, not only towards the end of the thesis writing stage, but also, in their special ways, throughout the entire process. I think I may have heard a sigh of relief. iv Abstract Consideration of forest management at the landscape scale is essential if commitments to the conservation of biodiversity are to be upheld. The ecosystem management approach, developed largely in North America, has made use of various landscape modelling tools to assist in planning for biodiversity maintenance and ecological restoration. The roles of habitat suitability models, metapopulation models, spatially explicit population models (SEPMs) and forest landscape dynamics models (FLDMs) in the planning process are discussed and a review of forest dynamics models is presented. Potential is identified for developing landscape models in the UK for both landscape restoration projects and semi-natural woodland management. Glen Affric, in northern Scotland contains a large area of native pine and birch woodland and is the subject of a long-term restoration project. A new model, GALDR (Glen Affric Landscape Dynamics Reconstruction) is introduced and is believed to be the first FLDM developed for British woodland. The theory behind the model is described in detail and preliminary results and sensitivity analyses are presented. Furthermore, GALAM (Glen Affric Lichen Abundance Model), a new SEPM for the rare epiphytic lichen Bryoria furcellata is also described. Results of simulations from the linked GALDR and GALAM models are presented which shed light on the role of landscape heterogeneity in determining the dynamics of lichen habitats and populations. It is concluded that, whilst much work will be required to develop a management-oriented decision support system from the GALDR model, the modelling process may aid researchers in the identification of knowledge gaps in ecological theory relevant to management and restoration. v Table of Contents 1 INTRODUCTION.............................................................................................. 1 1.1 THEMES, PROBLEMS AND TOOLS ....................................................................... 1 1.2 BIODIVERSITY................................................................................................... 3 1.2.1 Planning and management for biodiversity............................................. 4 1.2.2 Ecosystem management ........................................................................... 6 1.3 LANDSCAPE MODELLING APPROACHES ............................................................. 7 1.3.1 Habitat suitability models........................................................................ 7 1.3.2 Metapopulation models............................................................................ 8 1.3.3 Spatially explicit population models........................................................ 8 1.3.4 Forest landscape dynamics models ......................................................... 9 1.3.5 Integrated approaches to landscape modelling....................................... 9 1.4 UK PERSPECTIVES ON LANDSCAPE MODELLING .............................................. 11 1.4.1 Forest landscape restoration ................................................................. 12 1.4.2 Models for forest landscape restoration................................................ 13 1.4.3 Developing modelling solutions in the UK ............................................ 14 1.5 PROJECT AIMS ................................................................................................. 14 1.6 STUDY AREA – GLEN AFFRIC.......................................................................... 15 1.6.1 Situation ................................................................................................. 15 1.6.2 Geology.................................................................................................. 16 1.6.3 Soils........................................................................................................ 17 1.6.4 Climate................................................................................................... 17 1.6.5 Vegetation .............................................................................................. 17 1.6.6 History ................................................................................................... 22 1.6.7 Designations and Conservation Status .................................................. 23 1.6.8 Current management ............................................................................. 24 2 LITERATURE REVIEW OF FOREST DYNAMICS MODELS............... 25 2.1 INTRODUCTION ............................................................................................... 25 2.1.1 Types of forest dynamics models ........................................................... 25 2.2 GROWTH-YIELD MODELS ................................................................................ 28 2.3 ECOLOGICAL MODELS ..................................................................................... 30 2.3.1 Process models ...................................................................................... 30 vi 2.4 SUCCESSION MODELS ...................................................................................... 31 2.4.1 Transition models................................................................................... 31 2.5 GAP MODELS ................................................................................................... 40 2.5.1 Structure of gap models ......................................................................... 40 2.5.2 Development of gap models ................................................................... 45 2.5.3 Simplifying and approximating gap models........................................... 48 2.5.4 Spatially explicit gap models variants ................................................... 50 2.5.5 Summary of gap models and variants .................................................... 52 2.6 FOREST LANDSCAPE DYNAMICS MODELS......................................................... 54 2.7 CONCLUSIONS ................................................................................................. 62 3 DESIGN OF THE GALDR MODEL............................................................. 65 3.1 INTRODUCTION................................................................................................ 65 3.2 MODEL IMPLEMENTATION............................................................................... 65 3.2.1 Methods of implementing landscape models.......................................... 65 3.2.2 The SELES model development tool ...................................................... 66 3.3 OUTLINE OF THE GALDR MODEL STRUCTURE................................................ 69 3.3.1 Extent and spatial resolution ................................................................. 69 3.3.2 Timescale and temporal resolution........................................................ 70 1.1.3 Represented species ............................................................................... 71 1.1.4 Stand structure – dynamic state ............................................................. 72 1.1.5 Landscape attributes - static state.......................................................... 75 1.1.6 Dynamic behaviour ................................................................................ 76 1.4 ACQUISITION OF DATA FOR INITIAL AND STATIC STATE................................... 78 1.4.1 Initial primary state...............................................................................