ECOLOGICAL RESTORATION OF BIOCRUSTS IN ALPINE TUNDRA BIOMES by Annie-Claude Letendre B.Sc., University of Alberta, 2014 THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE IN BIOLOGY UNIVERSITY OF NORTHERN BRITISH COLUMBIA May 2018 © Annie-Claude Letendre, 2018 ii Abstract Biocrusts are complex communities of bryophytes, algae, fungi, lichens, and cyanobacteria living at the uppermost surface of soils. They have a global distribution and commonly colonize early successional and newly disturbed habitats, where they play important functional roles by facilitating key ecosystem processes. While several studies have examined biocrust development and function in arctic and alpine environments, the potential to use biocrusts in the restoration of disturbed soils in alpine tundra biomes has rarely been examined. In a greenhouse trial, we evaluated the restoration of biocrust through artificial inoculation of soils with mature biocrust. Our results suggest that artificial inoculation with biocrusts increases soil surface nitrogen-fixation rates. In a field study, we characterized alpine biocrust communities from cool mesic and xeric environments and conducted an inoculation experiment to assess the recovery of biocrust structure and function. Together these studies offer a comprehensive description of the functions of biocrusts in alpine environments and provide key information regarding the efficacy of using biocrusts for ecological restoration. ii Table of contents Abstract ................................................................................................................................................. ii Table of Contents ................................................................................................................................. iii List of Tables ......................................................................................................................................... vi List of Figures ....................................................................................................................................... vii Acknowledgements ............................................................................................................................. viii 1. Introduction and literature review ............................................................................................... 1 Soil Surface Disturbance Ecology ...................................................................................................... 1 Ecological Restoration ....................................................................................................................... 2 Spatial Heterogeneity and Site Preparation .................................................................................. 3 Biological Soil Crust Communities ..................................................................................................... 4 Abiotic Factors Influencing Biocrust Community Assembly and Function ....................................... 5 Biological Soil Crust Functions .......................................................................................................... 6 Extracellular polysaccharides ........................................................................................................ 7 Nutrient cycling ............................................................................................................................. 8 Restoration Techniques with Biocrusts ......................................................................................... 8 Summary ........................................................................................................................................... 9 2. Inoculation promotes microbial community reassembly and restoration of ecosystem function in alpine biocrusts – a microcosm experiment ................................................................................... 10 Introduction .................................................................................................................................... 10 Methods .......................................................................................................................................... 12 Site Description ........................................................................................................................... 12 Sample Collection ........................................................................................................................ 13 Microcosms ................................................................................................................................. 14 Bacterial 16S rRNA and fungal ITS2 sequencing ......................................................................... 15 Biocrust establishment ................................................................................................................ 17 Maximum photochemical quantum efficiency ........................................................................... 17 Nitrogenase activity .................................................................................................................... 18 nifH gene copy number ............................................................................................................... 19 Extracellular polysaccharide content .......................................................................................... 19 Soil properties ............................................................................................................................. 20 iii Data Analysis ............................................................................................................................... 20 Results ............................................................................................................................................. 22 Bacterial 16S rRNA and fungal ITS2 amplicon sequencing .......................................................... 22 Biocrust establishment ................................................................................................................ 25 Maximum photochemical quantum efficiency ........................................................................... 25 Nitrogenase activity and nifH gene copy number ....................................................................... 26 Extracellular polysaccharide content .......................................................................................... 26 Soil Properties ............................................................................................................................. 27 Discussion ........................................................................................................................................ 27 Fungal and bacterial communities of inoculated surfaces differ from uninoculated surfaces and from inoculant ............................................................................................................................. 27 Inoculation and microtopography facilitate biocrust establishment.......................................... 34 Inoculation and soil surface treatment promote function recovery .......................................... 35 Inoculation has limited effect on EPS and soil properties after 12 weeks .................................. 36 Conclusion ....................................................................................................................................... 38 3. Restoration of ecosystem function by soil surface inoculation of biocrust in mesic and xeric alpine ecosystems ............................................................................................................................... 39 Introduction .................................................................................................................................... 39 Methods .......................................................................................................................................... 40 Study Areas ................................................................................................................................. 40 Microclimate Monitoring of Natural Biocrust ............................................................................. 41 Natural Biocrust Cover Assessment ............................................................................................ 42 Field Experiment Design .............................................................................................................. 42 Natural Biocrust Sampling ........................................................................................................... 44 Acetylene-Reduction Assays ....................................................................................................... 44 Extracellular polysaccharide content .......................................................................................... 45 Soil properties ............................................................................................................................. 45 Data Analysis ............................................................................................................................... 46 Results ............................................................................................................................................. 47 Characterization of alpine biocrust ............................................................................................