Background
As both native and exotic species shift their distributions in response to climate warming and through biological invasions, many expand their ranges across elevational gradients. This expansion results in the reassembly of ecological communities, which meditates the effects of climate warming on biodiversity and key ecosystem functions. RangeX is a multidisciplinary, replicated field and laboratory experiment being conducted in climatically and socio-ecologically contrasting regions (Switzerland, Norway, China, South Africa) that seeks to better understand these range shifts in mountain habitats. We focus on mountain ecosystems as an ideal model system to address our research questions. Mountains are themselves of crucial conservation value, as hotspots of biodiversity, refugia for biota threatened by climate warming, and as key global sources of water, food, and livelihoods, but are experiencing above-average rates of warming and increasing pressures from invasive species and development, making mountains priority areas for sustainability research.
Experimental design
RangeX field experiments comprise warming treatments, introduction and removal of key plant species, and intensive monitoring of soils, plants and pollinators across multiple elevations. By investigating novel biotic interactions both above and below ground, we aim to: (i) disentangle the drivers of range expansions; (ii) uncover the consequences of range-expanders on biodiversity and ecosystem functioning; and (iii) predict the extent and impacts of future range expansions. Location: montane and lowland grasslands near Voss, Norway.
Opportunities
As a MSc student working within the RangeX project, you will:
• Do field work, and learn how to design and conduct ecological experiments, identify and measure plants and/or insect pollinators, manage and analyze ecological data, write it up as a thesis, and present your work in oral presentations within the team and at conferences.
• Be part of the ‘Between The Fjords’ lab group activities
• Be part of a large collaborative international research project, where you will participate in project meetings and workshops online and in person.
• Get to know and work with a cross-disciplinary group of researchers at different career stages, and see how your work relates to work on different functional groups and trophic levels.
• Be given opportunities to present your work at scientific conferences, and you will be supported in publishing your thesis as a scientific article.
We have listed multiple thesis options described below, but if you have other suggestions, don’t be afraid to contact us and ask!
Contact information
Nathan.Phinney@uib.no
Vigdis.Vandvik@uib.no
Project 1: Establishment success of range-expanding species in a montane grassland
Question: Can lowland grassland species successfully establish in a montane setting?
Methods: Our current experimental setup looks at the drivers and impacts of range-expanding plants by monitoring vital rates and functional traits of transplanted seedlings of lowland species in a mountain valley. Yet, this doesn’t allow us to test whether these plants are able to establish themselves via seeds. This can be investigated with an in-situ germination experiment using seeds. Seeds of our ten focal species would be sown within our established plots, where we can document seed germination success as a response to various treatments (e.g., artificial warming using OTCs). Data on germination rates and seedling traits will be valuable in parsing factors that drive the success/failures of range-expanding plants.
Project 2: Impacts of range-expanding plants on pollinator interactions
Question: Do range-expanding plant species disrupt plant-pollinator interactions?
Methods: Quantify insect visitation rates of the planted focal range-expanding species and selected native plants in the background community using novel image-based methodology. Images will be collected every minute each day during the growing season using time lapse cameras mounted over flowering plants from bud burst to seed set. At each site, 24 cameras will record focal range-expanding species, and native plants with matched floral traits next to and away from the range-expanding species. Deep learning convolutional neural networks (CNNs) will be used to automatically extract the timing, location, and identity of flower visitors from the images. This will allow us to quantify the importance of visitation rates, and visitor identity and diversity, for seed set of both native and range-expanding plant species. Sweep netting, pan trapping, and direct observation will be used to confirm the identity of observed flower visitors and their status as pollinators. The machine learning models will be trained on a manually labelled subset of images at each site. The field methodology has already been tested at sites in Greenland and Denmark, the analysis pipelines have been developed, and the most appropriate CNN models have been identified.
Project 3: Disentangling drivers of plant population establishment after range expansion
Question: What are the key processes underlying success of range-expanding species?
Methods: This is part of a replicated field experiment currently being conducted in Norway, Switzerland, South Africa and China in which plant communities are “invaded” with native range-expanding species transplanted upwards from lower elevations. We have chosen ten plant species that share similar habitat requirements and upper elevation limits, but that vary in functional traits and in the magnitude of their range shifts following recent warming. Plants are transplanted in a control “within-range” site near their current upper elevation limit, and in a higher elevation “beyond-range” experimental site with an approximately 2°C lower average mean annual temperature (i.e., corresponding to the theoretical upward range expansion given predicted warming this century). Experimental manipulations are used to test variation in novel species’ establishment at the beyond-range site, including artificial warming (using open-top chambers – OTCs). During the experiment, we will monitor key vital rates (growth, survival and reproduction of transplanted seedlings) of the focal species in each treatment. We will use mixed-effects models to determine the contribution of each factor (dispersal limitation, plant-plant interactions, soil conditions, climate limitation) to establishment success (vital rates/population growth, estimated with integral projection models).