Project highlights

  • Work with a range of ecologists in academia and practice  
  • Generate new knowledge that is directly relevant to setting conservation milestones and targets 
  • Provide empirical evidence to support theoretical ecology work  


Global biodiversity targets are repeatedly not met despite increasing conservation efforts. While in some cases this is due to inappropriate interventions or external pressures, in other cases, this is due to time lags in species’ responses to conservation efforts. Ecological time lags occur when there is a change to an ecosystem and species’ do not respond immediately. Extinction debt occurs following habitat destruction or degradation, and has been the focus of many theoretical and empirical studies [?]. The converse of this is ‘colonisation credit’ – where species’ do not respond immediately to restoration efforts.  

While there is an understanding that colonisation credit is a pervasive phenomena following habitat creation and restoration, there has been a failure to translate this ecological process into policy targets. Perhaps, because the empirical evidence for such lags is incomplete. These time lags suggest that when setting conservation targets, we also need to be setting milestones to ensure progress is on track.  

The aim of this project is to provide an empirical basis for ecological time lags across species, scales and ecosystems. Building on theoretical and modelling work led by PI Graham and Co-I Watts, the project will aim to quantify ecological time lags and to test hypotheses generated by the theoretical work. We will aim to quantify the variation in the lag between restoration and meeting conservation targets, depending on (a) ecosystem type (forest or grassland), (b) species life history traits, and (c) landscape composition and configuration. The work will occur across three scales: a global synthesis will allow us to identify regions which show habitat gains and to unpick how these gains translate into changing trends for a range of species; at the national (UK) scale, we will dig deeper into these trends to understand how long restoration efforts take to yield biodiversity benefits across different taxa; at site scale, we will further develop our understanding of these lags and how they vary between species.  

On the top row there are three stylised landscapes with eight habitat patches of varying sizes. In the first these are all grey, representing current habitat. In the second, four are yellow, representing those patches which have been removed or destroyed. In the third four are green, representing those which have been restored. At the bottom there is a graph showing the hypotheised relationship between species abundance (or richness) through time with markers showing the habitat destruction or creation. There are separate lines showing the hypothesised relationship for total species (this has a sharp decline after destruction and gradual recovery after creation); generalist species (this has a less steep decline after destruction, and more immediate recovery after creation; specialist species (persistent decline after destruction, slow recovery after creation); and sensitive species (short lived die out after destruction; long-lived continue to decline even after new habitat creation).

Figure 1: Hypothesised time lags following habitat destruction (first line, yellow patches), and then habitat creation (second line, green patches) for different species types.  

Case funding

This project is suitable for CASE funding


University of Birmingham


  • Organisms and Ecosystems


Project investigator

Laura Graham, University of Birmingham, [email protected]


Adriane Esquivel Muelbert, University of Birmingham, [email protected]

Kevin Watts, Forest Research, [email protected]

How to apply


The research will consist of three parts:  

  1. A global data synthesis where remote sensing imagery will be analysed to develop trends of habitat loss and gain for grasslands and forests. This will be combined with time series of species abundances from the BioTime database. Using metaregression techniques the time lag for response in biodiversity indicators will be quantified and it’s variability by species and landscape context identified.  
  2. Using a chronosequence of UK forest cover change from 1990-present we will be able to dig deeper into our understanding of time-lags in a particular ecosystem 
  3. A local field study of meadow creation in the West Midlands (2012-present) will allow us to estimate time lags in recovery in grassland.  

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 receive training in cutting edge ecological modelling and remote sensing techniques. You will also benefit from the range of applied and theoretical ecology expertise of the supervisory team. The fieldwork component of the project will allow you to develop specific ecological survey techniques. Additionally, you will be part of the growing Ecology & Biogeography group at the University of Birmingham, which has a number of researchers across all career stages in the general field of ecology. As part of the Land Use and Ecosystem Services group at forest research you will be able to attend remote lab meetings and further extend your network. 

Partners and collaboration

The PhD project will work closely with CASE partner Kevin Watts at Forest Research. Kevin has a wealth of expertise in landscape ecology – both theoretical and applied – and has driven the colonisation credit research this project is building on.  

The project will also work with the Birmingham and Black Country Wildlife Trust and EcoRecord who led the meadow creation scheme and hold the data. They will be able to advise on the field survey and will benefit from data gathered for this project.  

Further details

Further details on how to contact the supervisor for this project and how to apply for this project can be found here: 

For any enquiries related to this project please contact Laura Graham, [email protected]. 

To apply to this project: 

  • You must include a CENTA studentship application form, downloadable from: CENTA Studentship Application Form 2024. 
  • You must include a CV with the names of at least two referees (preferably three) who can comment on your academic abilities. 
  • Please submit your application and complete the host institution application process via: Please select the PhD Geography and Environmental Science (CENTA) 2024/25 Apply Now button. The CENTA application form 2024 and CV can be uploaded to the Application Information section of the online form.  Please quote CENTA 2024-B16  when completing the application form. 

Applications must be submitted by 23:59 GMT on Wednesday 10th January 2024. 

Possible timeline

Year 1

Project development and general training (i.e. statistics, project management, data synthesis). Planning of field study, with first data collection in the summer of this year. Begin bringing together the datasets for use in the project (chronosequence, bioTime, land-cover). 

Year 2

Paper writing, analysis of initial data, ongoing fieldwork, conference attendance.

Year 3

Data analysis, paper- and thesis-writing, and conference attendance.

Further reading

Dornelas, M., et. al, 2018. BioTIME: A database of biodiversity time series for the Anthropocene. Global Ecol Biogeogr 27, 760–786.  

Hughes, S., Kunin, W., Ziv, G., & Watts, K. (2023). Spatial targeting of woodland creation can reduce the colonisation credit of woodland plants. Ecological Solutions and Evidence, 4, e12263. 

Jackson, S.T., Sax, D.F., 2010. Balancing biodiversity in a changing environment: extinction debt, immigration credit and species turnover. Trends in Ecology & Evolution 25, 153–160.  

Watts, K., Whytock, R.C., Park, K.J. et al. Ecological time lags and the journey towards conservation success. Nat Ecol Evol 4, 304–311 (2020).