Overview

Project Highlights:

  • Using field experiments to develop change metrics for grassland ecosystems
  • Field work at a new climate change experiment, at sites across the UK, and in Austria
  • Integrating ecophysiological and field spectroscopy data

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 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. A spatial comparison will be made through measurements at a continental grassland site in Austria. Data and results will be integrated into a process-based canopy radiative transfer model and compared with remote sensing data.

The rain shelters and irrigation system in operation at the RainDrop experimental site at Wytham, near Oxford.

Methodology

The RainDrop LTE was established in 2016 and will be entering its 5th 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

You will gain experience in field spectroscopy and plant ecophysiological 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.

Timeline

Year 1: Literature review, instrument and technique training, first season fieldwork and analyses.

Year 2: Second season of fieldwork, including extension to other sites. Attend BES Annual Meeting.

Year 3: Final measurements and data analysis. Attend EGU conference. CENTA placement.

Year 4: Complete writing up

The student will be encouraged to participate in local and international meetings and develop their own networks through the course the PhD.

Partners and collaboration (including CASE)

The possibility of a CASE partnership with Natural England is being explored. The project will benefit from collaboration with the Biometeorology group at The University of Innsbruck, led by Georg Wohlfahrt. You will also have the opportunity to collaborate and with other students and researchers at the site from Oxford University. RainDrop is also part of the international DroughtNet network.

Further Details

We invite applications from students with a strong background in plant, ecosystem ecology 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.

Please contact Dr Kadmiel Maseyk, kadmiel.maseyk@open.ac.uk for further information.

The successful student will join a well-established team researching environmental and ecosystem processes and a vibrant postgraduate community at the Open University.

Applications should include: