2025-OU8 Hyperspectral signals of change in grassland ecosystems

Project highlights

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

Overview

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.

Host

The Open University

Theme

Climate and Environmental Sustainability
Organisms and Ecosystems

Supervisors

Project investigator

Dr Clare Lawson, Open University, ([email protected])

Co-investigators

Dr Kadmiel Maseyk, Open University, ([email protected])
Dr Holly Croft, University of Sheffield, ([email protected])

How to apply

Each host has a slightly different application process.
Find out how to apply for this studentship.
All applications must include the CENTA application form.
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Methodology

The RainDrop LTE was established in 2016 and will be entering its 10th 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

DRs will be awarded CENTA Training Credits (CTCs) for participation in CENTA-provided and ‘free choice’ external training. One CTC can be earned per 3 hours training, and DRs must accrue 100 CTCs across the three and a half 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.

Further details

For any enquiries related to this project please contact Dr Clare Lawson ([email protected]). 

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.

To apply to this project: 

You must include a CENTA studentship application form, downloadable from: CENTA Studentship Application Form 2025.

You must include a CV with the names of at least two referees (preferably three) who can comment on your academic abilities.

Your application materials, including the CENTA Studentship Application Form 2025, your CV and the Open University application form must be emailed to [email protected]. Instructions on how to apply to the Open University are to be found on https://www5.open.ac.uk/stem/environment-earth-ecosystem-sciences/research/phd-students/current-opportunities-and-how-apply, please ensure you read this webpage before applying as you will need to obtain the relevant OU application form from here. Please quote CENTA 2025-OU8 when completing the application form.

 Applications must be submitted by 23:59 GMT on Wednesday 8th January 2025. 

Possible timeline

Year 1

Literature review, instrument and technique training, first season fieldwork.

Year 2

Data analysis, and second season of fieldwork, including extension to other sites. National conference presentation.

Year 3

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 the PhD.