- Using long-term field experiments to develop change metrics for grassland ecosystems
- Field work at a climate change experiments across the UK
- Integrating ecophysiology, biodiversity, and field spectroscopy
The driving forces of climate change and land management affect ecosystem natural capital through their impacts on ecosystem structure and function. Calcareous grasslands are ecosystems of high conservation importance due to their high biodiversity but are becoming increasingly rare due to conversion to arable land. Understanding the impact of global change processes on these ecosystems is therefore key to their conservation. To understand ecosystem responses to climate change we use long-term experiments (LTEs): field-based manipulation of specific climate factors or nutrient levels in a controlled manner to simulate future conditions. When run over the long term (i.e. multi-year to decadal), they provide valuable insight into the nature and direction of shifts in ecosystem processes (Grime et al 2007, Sayer and Silvertown 2019). We can also use these experiments to identify the signals associated with ecosystem change and apply this knowledge to understanding contemporary change dynamics. Changes in leaf and canopy traits, physiology, and species composition change the magnitude and spectral composition of vegetation reflectance (Peng et al. 2018, Punalekar et al. 2016) which is being measured through systems on canopy, drone, airborne and satellite platforms. Therefore, knowing the relationship between spectral signals and vegetation climate change responses can help us identify and quantify rates of contemporary change.
This project will investigate ecosystem responses to environmental change and the associated reflectance spectra in grassland ecosystems. It will focus on the impacts of hydrological change (drier and wetter) on calcareous grassland at the RainDrop LTE, located in a Natural England SSSI at Wytham, Oxfordshire (Fig.1). Field spectroscopy will be combined with measurements of plant and ecosystem structure and function and species diversity to identify the signals associated with climate change impacts. Measurements will also be made at other grassland experimental sites in the Ecological Continuity Trust register across the UK to identify general and specific responses to change. Data and results will be integrated into a process-based canopy radiative transfer model and compared with remote sensing data.
Figure 1: The rain shelters and irrigation system in operation at the RainDrop experimental site at Wytham, near Oxford.
HostThe Open University
- Climate and Environmental Sustainability
- Organisms and Ecosystems
The RainDrop LTE was established in 2016 and will be entering its 8th year of treatment at the start of this project. Rain shelters are used to intercept 50% of incident rainfall over 25 m2 treatment plots, to impose a drought treatment, and this is simultaneously distributed by irrigation on an adjacent plot, for a wetting treatment. High-resolution spectroscopy using a dual-field-of-view spectrometer system will be used to measure reflectance indices and solar induced fluorescence in the field across the treatments and sites. Leaf and ecosystem properties that underpin canopy reflectance and radiation transfer models will be quantified, including leaf chlorophyll content, fluorescence, optical properties and leaf area index. Depending on the interests of the student, there are options to further explore the links with plant physiology and species diversity, incorporate this information into a modelling framework or contextualise remote sensing data.
Training and skills
Students will be awarded CENTA2 Training Credits (CTCs) for participation in CENTA2-provided and ‘free choice’ external training. One CTC equates to 1⁄2 day session and students must accrue 100 CTCs across the three years of their PhD.
You will gain experience in field spectroscopy and plant ecophysiological and measurements, data handling and analysis. You will receive the necessary training in all analytical techniques and instrument use. You will also be supported in the development of your skills in field planning and project management, including liaising with external organisations and sites. A rich and varied training programme is available to OU PG students which includes sessions on academic writing, research design and data management, career development communicating your research, as well as opportunities to get involved in public engagement, media and remote digital teaching.
Partners and collaboration
The possibility of a CASE partnership with Natural England will be explored once projects are confirmed. You will also have the opportunity to collaborate and with other students and researchers at RainDrop and other ECT network sites. RainDrop is also part of the international DroughtNet network.
We invite applications from students with a strong background in plant, ecosystem or grassland ecology, physiology or remote sensing, an interest in global change processes and an enthusiasm for field work and independent research. Clean driving licence for accessing UK field sites is desirable.
The successful student will join well-established teams researching environmental and ecosystem processes and a vibrant postgraduate community at the Open University.
If you wish to apply to the project, applications should include:
- A CENTA application form, downloadable from: CENTA application
- A CV with the names of at least two referees (preferably three and who can comment on your academic abilities)
- An Open University application form, downloadable from: Home OU application form (if you are resident in the UK) or an Overseas OU application form (if you are an international applicant). Please quote CENTA23_OU9 when completing the application form.
- Please send your completed application to: [email protected]
Applications to be received by the end of the day on Wednesday 11th January 2023.
Literature review, instrument and technique training, first season fieldwork.
Data analysis, and second season of fieldwork, including extension to other sites. National conference presentation.
Final measurements, complete data analysis and writing up. International conference presentation.
The student will be encouraged to join national and international network programmes such as COST Actions and develop their own networks through the course of the PhD.
Grime J.P., et al. (2008) ‘Long-term resistance to simulated climate change in an infertile grassland’. PNAS 105, 10028-10032. doi: 10.1073/pnas.0711567105
Sayer E.J., and Silvertown J. (2019) ‘Long-term ecological experiments forever! – Unique challenges and opportunities.’ BES Virtual Issue. Available at https://besjournals.onlinelibrary.wiley.com/hub/long-termexperiment.
Peng Y., et al (2018) ‘Assessment of plant species diversity based on hyperspectral indices at a fine scale’. Scientific Reports 8, 4776 doi: 10.1038/s41598-018-23136-5
Punalekar, S., et al (2016) ‘Characterization of a Highly Biodiverse Floodplain Meadow Using Hyperspectral Remote Sensing within a Plant Functional Trait Framework.’ Remote Sensing, 8(2), 112. doi: 10.3390/rs8020112
Data collection is outdoors, minimising infection risk, or involves desk-based data analysis that can be done in low occupancy offices or at home. Where lab work is involved, a low dependence on time-critical analysis (samples can be stored frozen or dried) means this can be flexibly incorporated into lab booking schedules.