The Effect of Irrigation with Wastewaters on the Abundance of Bio-Indicators in Established Short Rotation Coppice Willow Plantations
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The effect of irrigation with wastewaters on the abundance of bio-indicators in established short rotation coppice willow plantations By James Feighan For the degree of Masters of Science (Environmental Science) Supervisor: Dr Ann Marie Duddy Submitted to Institute of Technology, Sligo December, 2014 Abstract This study investigated the effect of irrigation with wastewaters on the abundance of earthworms, mites and springtails in established short rotation coppice willow plantations. The study examined two different sites in Northern Ireland over two consecutive irrigation periods in 2012 and 2013. Site one (8,100m2) was located at Culmore, Co. Derry and was irrigated with primary treated effluent from a nearby wastewater treatment plant at a rate of 30m3/ha/d. Site two (23,700m2) was located at Hillsborough, Co. Down and was irrigated at variable rates (18, 34 and 44 m3/ha/d) with dairy parlour washings from an on-site farm. Earthworms were extracted by a combination of chemical extraction (mustard solution) and hand-sorting. Mites and springtails were extracted using Berlese-Tullgren funnels. Earthworms proved to be useful bio-indicators to monitor the impact of irrigation with dairy wastewater at site two since their abundance significantly decreased at the highest irrigation rates used at this site (i.e. 34 and 44 m3/ha/day). The abundance of earthworms was not significantly affected by irrigation with municipal wastewater at site one. A variety of earthworm species were recovered in sites one and two (n=8 and n=11, respectively) but the majority of these were present in low numbers. Acid-tolerant earthworm species occurred in greatest numbers at both sites. The abundance of mites and springtails was not affected by irrigation with wastewater in sites one or two, regardless of application rate. Previous land-use significantly affected the abundance of earthworms and mites at site one. A greater abundance of earthworms was observed in plots that had been previously planted with grassland prior to SRC willow conversion in 2010, while a greater abundance of mites was observed in plots that had been previously planted with poplar. No interaction factor was evident between previous cropping history and irrigation. i Declaration I declare that this thesis is entirely my own work, except where otherwise stated and has not been previously submitted to any other institute or university James Feighan This project was part-financed by the Europeans Union’s European Regional Development Fund through INTERREG IVA cross-border programme, managed by the special EU programmes body ii Acknowledgements I would like to thank Professor Alistair McCracken, Chris Johnston, Linda Walsh and all the staff at the Agri-Food and Biosciences Institute, Belfast for assistance in site access and supplying information. I also wish to thank Karen McDowell, Northern Ireland Water, for all of her help throughout the project. In addition, my sincere gratitude is extended to other ANSWER project partners, Teagasc, Donegal County Council, South West College and Monaghan County Council. I wish to thank my supervisor Dr Ann Marie Duddy for her support and immense patience throughout the course of the project. And finally, thank you to my friends, family and all the other researchers at I.T Sligo who helped keep me sane throughout the project. iii Table of Contents Table of Contents ........................................................................................................... iv List of Figures ................................................................................................................ vii List of Tables ................................................................................................................ viii List of Plates ................................................................................................................... xi Abbreviations and Organisations ................................................................................ xii Chapter 1 Introduction .............................................................................................. 1 Chapter 2 Literature Review.................................................................................... 7 2.1 Short Rotation Coppice Willow Plantations....................................................... 7 2.1.1 Life Cycle .................................................................................................... 8 2.2 Soil monitoring using bio-indicators ................................................................ 11 2.3 Earthworms ..................................................................................................... 12 2.3.1 Identifying Features .................................................................................. 14 2.3.2 Seasonal Population Trends ...................................................................... 15 2.3.3 Feeding Habits .......................................................................................... 16 2.3.4 Factors Affecting the Abundance of Earthworm ...................................... 16 2.3.5 Earthworm Sampling Methods ................................................................. 23 2.4 Mites ................................................................................................................. 26 2.4.1 Identifying Features .................................................................................. 27 2.4.2 Feeding Habits .......................................................................................... 27 2.4.3 Seasonal Population Trends ...................................................................... 28 2.4.4 Abiotic Factors Affecting the Abundance of Mites .................................. 29 2.4.5 Extraction of Mites .................................................................................... 31 2.5 Springtails ......................................................................................................... 33 2.5.1 Identifying Features ................................................................................. 33 2.5.2 Feeding Habits .......................................................................................... 34 2.5.3 Seasonal Population Trends ...................................................................... 35 iv 2.5.4 Abiotic Factors that Affect the Abundance of Springtails ........................ 35 2.5.5 Extraction of Springtails ........................................................................... 37 2.6 The Impact of SRC Willow Plantations on Soil Invertebrates ......................... 38 2.7 The Impact of Irrigated SRC Willow Plantations on Soil Invertebrates .......... 40 Chapter 3 Methodology ............................................................................................ 43 3.1 Culmore Site Description ................................................................................. 43 3.2 Hillsborough Site Description .......................................................................... 46 3.3 Choice of Bio-Indicator .................................................................................... 49 3.4 Sampling Regime ............................................................................................. 49 3.4.1 Culmore ..................................................................................................... 49 3.4.2 Hillsborough .............................................................................................. 50 3.5 Earthworm Extraction ...................................................................................... 52 3.6 Extraction of Springtails and Mites .................................................................. 53 3.7 Physical/Chemical Analysis ............................................................................. 55 3.8 Statistical Analysis ........................................................................................... 55 3.9 Limitation of Experimental Set-up ................................................................... 56 Chapter 4 Results ...................................................................................................... 57 4.1 Abundance of Bio-Indicators at Culmore SRC Willow Plantation .................. 57 4.1.1 Earthworms ............................................................................................... 57 4.1.2 Mites .......................................................................................................... 63 4.1.3 Springtails ................................................................................................. 67 4.1.4 Relationship between the Abundance of Earthworms, Springtails and Mites and Soil Characteristics ................................................................................. 72 4.2 Abundance of Bio-Indicators in Hillsborough SRC Willow Plantation .......... 76 4.2.1 Earthworms ............................................................................................... 76 4.2.2 Mites .......................................................................................................... 82 4.2.3 Springtails ................................................................................................. 86 v 4.2.4 Relationship between Abundance of Bio-indicators and Soil Characteristics .......................................................................................................... 89 Chapter 5 Discussion ................................................................................................