The impact of land-use intensification on the conservation management of native forest remnants embedded within production landscapes Lisa H. Denmead B. Sc. (Biology), University of Canterbury, New Zealand This thesis is presented for the degree of Masters of Science by Research in Ecology School of Animal Biology The University of Western Australia 2012 Declaration I declare that this thesis is my own account of my research conducted during my period of enrolment at the University of Western Australia for the degree of Master of Science by Research. It has not previously been submitted for a degree at this or any other university. As stated in my Acknowledgements, my research has been assisted by interactions with a number of people, however any work that was shared with supervisors or other collaborators is mentioned below: Chapter Two: The research completed in this chapter was carried out as part of the larger research project - Riches to Rags: does elevated productivity drive ecosystem decay in adjacent natural habitats. I was fully involved in developing the study design for this project, which I used to answer the questions addressed in chapter two. Collaborators on this project include Raphael Didham, Elizabeth Deakin, Gary Barker, Jason Tylianakis and Louis Schipper. All the field and lab work for this chapter was carried out alongside my fellow student on the project, Elizabeth Deakin. I developed the research questions, carried out the analysis and wrote the chapter with the support of my supervisors Raphael Didham, Rachel Standish and Gary Barker. Chapter Three: The experiment in this chapter was conducted in one of the forest remnants used in the wider project but was separate from the main aims of the project. I developed the research questions, designed the experiment, carried out the analysis and wrote the chapter with the support of my supervisors Raphael Didham, Rachel Standish and Gary Barker. Abstract Land-use intensification is increasing worldwide as the need for resources grows along with the human population. The increased inputs and animal stocking rates that are part of increasing yields in production systems have negative impacts on farmland. However, farmer inputs are not static and can spill-over into adjacent natural systems, sometimes with harmful consequences. Actions taken to spare land for conservation will be compromised if spill-over from surrounding land-use inhibits recovery of the system. In the first half of my thesis I investigated the relative benefits of livestock exclusion for conservation of native forest remnants embedded within production landscapes of varying land-use intensity in the Waikato region, New Zealand. I measured detritivore invertebrate communities and leaf-litter decomposition rates in 11 fenced and 10 unfenced native forest remnants on farmland that varied in land-use intensity. Livestock exclusion was highly beneficial to detritivore communities under all land-use intensities. But surprisingly, the observed variation in detritivore community composition was independent of changes in land-use intensification in both fenced and unfenced remnants and therefore the relative benefit of fencing did not change with land- use intensity. These results have positive implications for land spared for conservation in New Zealand. I tested the mechanistic drivers of livestock trampling impacts on land snail communities in the second half of my thesis, using an artificial trampling experiment conducted in a fenced forest remnant. I used a factorial combination of litter manipulation and trampling treatments to partition different causal drivers of livestock impacts on land snail communities, and relate treatment differences to covariance in five environmental variables which are impacted by livestock. Even the lowest intensity treatment caused severe changes to snail communities. The underlying drivers varied, but are primarily due to changes in litter mass and the effects of unknown mediating variables that were not measured in the experiment. The results suggest that even a minimal amount of stock access will cause significant impacts on snail communities, and should be discouraged. The results also further support the need to maintain livestock exclusion as a priority conservation management action for forest remnants on farmland. Acknowledgements Firstly I’d like to thank to my supervisors Raphael Didham, Rachel Standish and Gary Barker. Raph, I have learnt an immeasurable amount from working with you and you pushed me and this thesis further than I ever could have. Also, thanks for giving me the opportunity and supporting my transfer to UWA, it has been an amazing opportunity for me, and I have got so much more out of my MSc because of it. Rachel, thanks a lot for getting so involved, especially after having to jump in part way through, I appreciate the time you take to think over my work and your support throughout this. Gary, thanks for your advice in developing my research, particularly the experiment and for your support over the summers I’ve been based at Landcare Research. And thank you so much for getting through the snail identifications for me, this research could not have been done without you. I thank my fellow student on the project, and co-author on chapter 2 of this thesis, Liz Deakin, right from the beginning we helped each other through and I’m extremely grateful for that. We went through hell but we survived! I thank the collaborators on the wider Marsden project, Jason Tylianakis and Louis Schipper for their input and advice. This research was possible due to financial support from the School of Animal Biology at the University of Western Australia and the Marsden Fund in New Zealand. My stipend was also provided by a University of Western Australia University Postgraduate Award. Numerous people have helped me in the field and lab. Foremost, I would like to thank our project technician Scott Bartlam, none of this could have been done without him. He went out of his way and far beyond what was expected to help make my work the best it could be. He also taught me numerous skills that will be invaluable to me in my future research. Thanks to our favourite field assistant TK (Terrekia Madden), I know it was killer work some times, but the amount of effort put in was greatly appreciated. I thank Daniel Arnold, for getting through the mechanical hoof experiment with me. I thank Hannah Franklin for help in the field and the lab, and more than that, thanks for helping me get through the summer. Thanks to Josh Van Vianen, Marion Theile, Jayesh Ravji, and Lowell Abellonosa for help sorting invertebrates and Louise Fisk for doing a great job of the soil analysis for us. I’d like to thank the staff at Landcare Research Hamilton, the support I had during the two summers I was based there was invaluable. Everyone was always so willing to help out if they could. In particular, Marc Dressor thank you for the help designing the mechanical hoof. I am grateful for all my friends that have supported me along the way, even if it has just been to listen to me complain over and over and over (Daniel Paine), or do overnight rushed jobs for me (Richard Langrish). I’ve been lucky enough to go through my MSc with a great bunch of people from both UC and UWA, providing ongoing support and many of whom I know will remain friends for life. Special thanks should go to Andrew Barnes for the stats lessons, and my lab group at UWA for their advice, support and just being genuinely lovely people! Last but definitely not least, my family. Mum you are amazing; I couldn’t have done any of it without you. My sister, thanks for the support Nae, you’ve been really awesome through this. Mostly I’m grateful for all the other stuff, but thanks again for helping me get through those samples both of you-I would never have finished them otherwise. Thanks Dad for being there, and for all the advice throughout, and to both you and Ginni for help with the final editing. To my nieces Zoey and Millie, thanks for being you. Table of Contents Chapter 1. General Introduction .......................................................................... 1 A brief history of global land-use intensification .................................... 1 The effects of land-use intensification on biodiversity ........................... 2 Multiple drivers of biodiversity loss in habitat remnants embedded within production landscapes ................................................................ 5 Balancing biodiversity conservation and agricultural production ........... 6 Management actions to conserve and restore biodiversity in production landscapes ......................................................................................... 10 Thesis Aims and Objectives ............................................................... 11 Chapter 2. Do spill-over effects from high intensity agriculture compromise land spared for conservation? .................................................................................. 17 Introduction ......................................................................................... 17 Methods .............................................................................................. 21 Results ................................................................................................ 32 Discussion .......................................................................................... 43 Appendix 2.1 ......................................................................................