Project highlights

  • The doctoral researcher will work with a multidisciplinary team of scientists (landscape ecologists, entomologists, ornithologists, forest ecologists) to design a sample framework to disentangle biodiversity patterns across ‘Tiny forest’ plots distributed across a gradient of urbanisation in the West Midlands. 
  • The project design, characterised by plots of the same size, is a natural experiment that permits testing of hypotheses related to the important habitat area/habitat configuration debate in landscape ecology. 
  • Project results will be used to inform landscape managers and those working in nature conservation on how to use woodlands to support urban biodiversity with Earthwatch and local residents who generate the citizen science data.  


Urbanisation is a driving force in biodiversity change at a global level (McDonald et al. 2020), affecting species’ assemblages, and affecting functional ecology across multiple taxa (Hahs et al., 2023). Its impact is typically assessed using gradient approaches (McDonnell, & Hahs, 2008). While the results of many gradient studies show pervasive impacts on assemblage structure and individual populations, direct causal association of the processes involved (e.g. isolation, fragmentation) is problematic as these factors covary along the gradient. For example, site size typically decreases, and habitat fragmentation increases moving from rural to urban areas.  

While woodlands are known to provide habitat and enhance connectivity for a wide range of organisms (e.g. Croci et al. 2008; Hale et al. 2013; Soga et al. 2014), previous gradient studies (e.g. Sadler et al. 2006) have shown them to be particularly impacted by metrics indicative of fragmentation and reduced connectivity (e.g. site size, distance to nearest similar habitat). Disentangling the role of area effects from those of site isolation along urban gradients is problematic (Fahrig, 2013) but research syntheses point the importance of increased habitat area (e.g. Bennicke et al. 2015). Little research exists on the value of habitats of smaller size although recent work on ‘Tiny Forest’ (Earthwatch, 2023a,b) indicates their promise. 

Here, we use a novel natural experiment in the West Midlands, drawn from a sample of >200 ‘Tiny Forest’ plots, to test how tree species’ establishment and its associated biodiversity is structured along an urbanisation gradient. Crucially, plot size is held constant, therefore controlling for area effects, allowing us to understand how site characteristics such as site age and tree composition influence biodiversity metrics in sites in urban areas with different landscape characteristics. 

This project will examine: (i) the impact of urbanisation on plot biodiversity, and test how (ii) landscape habitat configuration around the plot impacts plot establishment, and biodiversity assembly, (iii) plot age and (iv) plot tree species mixes affect biodiversity across trophic levels. This work will inform management recommendations for the use of ‘Tiny Forests’ as restoration and conservation tools in urban areas where woodlands are not extensive.  



University of Birmingham


  • Climate and Environmental Sustainability
  • Organisms and Ecosystems


Project investigator

Prof. Jon Sadler (GEES, UoB, [email protected])


Dr Laura Graham (GEES, UoB, [email protected])

Dr Jim Reynolds (BIO, UoB, [email protected])

Dr Thomas Matthews (GEES, UoB, [email protected])

Dr Adriane Esquivel Muelbert(GEES, UoB, [email protected])

Dr Claire Narraway (Earthwatch[email protected])

How to apply


We will use a multi-scale landscape ecology design (Spake et al. 2019) to investigate multi-taxa and multi-trophic level biodiversity from a sample of >200 Tiny Forest plots distributed across an urban gradient in the West Midlands (Fig. 1). Plot area is fixed at 200 m2, controlling for plot size and letting site landscape context vary. The number of plots will allow for a crossed sampling framework stratifying plot age and tree species’ mixes, allowing landscape configuration and site factors to be considered in relation to tree establishment and biodiversity assembly. 

Multi-taxa audits of the plots will use a suite of indicator species (e.g. tree, ground-dwelling invertebrates, pollinators, butterflies, birds) and will include acoustic surveys with AudioMoths. Secondary data from remote sensing imagery will be used to contextualise landcover around plots at varying spatial scales. The environmental/remote-sensing and biodiversity data will form the basis of statistical models using R. 

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.  

This project combines landscape ecology, statistics and woodland ecology. Training will be provided in each subject area within the host/partner institutions and CENTA. It will involve instruction in using R for the analysis of complex datasets and remote sensing using Google Earth Engine. The candidate will develop taxonomic identification skills covering the indicator groups, coupled with training in forest plot monitoring/tree health. The candidate will work with Earthwatch to build an understanding of how to conduct engaged environmental research, the practicalities of implementing urban green infrastructure, networking through participation in the Miyawaki Research Network, and experience of working in a prominent environmental charity. 

Partners and collaboration

The project is a partnership project with a new CENTA partner, Earthwatch, mapping directly into their UKwide ‘Tiny forests’ programme (Earthwatch 2023b). The programme is entering its 5th year and there are now >200 forest plots in urban areas using bespoke planting mixes related to the specific site conditions (Earthwatch, 2023b). This project will be the first systematic assessment of trophic links across a sample of tiny forests on a gradient of urbanisation. The supervisory team is diverse including specialists in invertebrates, birds, forest ecology, statistical and mathematical modelling, permitting the candidate to chart their own course through the programme. 

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:


Prof. Jon Sadler ([email protected]); Dr Laura Graham ([email protected]), Dr Adriane Esquivel Muelbert ([email protected]); Dr Thomas Matthews ([email protected]); Dr Jim Reynolds ([email protected]) 


Dr Claire Narraway ([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-B41  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 DR training (e.g. statistics, taxonomy). Analysis of existing Tiny Forest datasets prior to the selection of field sites for the survey work and commencement of a ‘pilot survey’ to test and refine the methodology at each site. 

Year 2

Paper writing, fieldwork in the West Midlands sites and conference attendance.

Year 3

Ongoing fieldwork, data analysis, academic paper and thesis writing. Conference attendance.

Further reading

Beninde, J., Veith, M. and Hochkirch, A. (2015) Biodiversity in cities needs space: A meta-analysis of factors determining intra-urban biodiversity variation. Ecology Letters, 18, 581–592. 

Earthwatch (2023a) Tiny Forest Monitoring Report 2023, Earthwatch Europe, Oxford. URL: 

Earthwatch (2023b): ‘Tiny forest’: (accessed 19th Sept. 2023. 

Fahrig, L. (2013) Rethinking patch size and isolation effects: The Habitat Amount Hypothesis’. Journal of Biogeography, 40, 1649–1663. 

Hahs, A.K., Fournier, B., Aronson, M.F.J., Nilon, C.H., Herrera-Montes, A., Salisbury, A.B., Threlfall, C.G. et al. (2023) Urbanisation generates multiple trait syndromes for terrestrial animal taxa worldwide. Nature Communications, 14, 47–51. 

Hale, J.D., Fairbrass, A.J., Matthews, T.J. and Sadler, J.P. (2012) Habitat composition and connectivity predicts bat presence and activity at foraging sites in a large UK conurbation. PLoS ONE, 7, e33300. 

McDonald, R.I., Mansur, A.V., Ascensão, F., Colbert, M., Crossman, K., Elmqvist, T., Gonzalez, A. et al. (2020) Research gaps in knowledge of the impact of urban growth on biodiversity. Nature Sustainability, 3, 16–24. 

McDonnell, M.J. and Hahs, A.K. (2008) The use of gradient analysis studies in advancing our understanding of the ecology of urbanizing landscapes: Current status and future directions’. Landscape Ecology, 23, 11431155. 

Sadler, J.P., Small, E.C., Fiszpan, H., Telfer, M.G. and Niemelä, J. (2006) Investigating environmental variation and landscape characteristics of an urban–rural gradient using woodland carabid assemblages’. Journal of Biogeography, 33, 1126–1138. 

Soga, M., Yamaura, Y., Koike, S. and Gaston, K.J. (2014) Woodland remnants as an urban wildlife refuge: A cross-taxonomic assessment. Biodiversity and Conservation, 23, 649–659. 

Spake, R., Bellamy, C., Graham, L.J., Watts, K., Wilson, T., Norton, L.R., Wood, C.M., Schmucki, R., Bullock, J.M., Eigenbrod, F., 2019. An analytical framework for spatially targeted management of natural capital. Nature Sustainability 2, 90–97.