Project highlights

  • Biodiversity modelling of a species-rich yet understudied group
  • Comparison of multiple diversity gradients
  • Interactive effects of environmental change drivers on biodiversity.


We live in a time of radical changes and rapid biodiversity loss. To make better predictions of the impacts of anthropogenic change on the world’s declining biodiversity, it is crucial to first understand how species are naturally distributed and then assess how their distribution might shift or, worse, disappear. Biodiversity is unequally distributed across the Earth, increasing towards low latitudes, low to intermediate elevations, and intermediate canopy heights within forests. These spatial gradients reflect differences in environmental variables, such as luminosity, temperature and humidity, which affect physiological, demographic, and biotic interaction processes. Species show different preferences for these variables (i.e. ecological niche), which causes biodiversity to peak in areas of high niche overlap, provided that coexistence mechanisms are at play. Both niche-related variables and coexistence mechanisms are being disrupted by humans. Because many environmental variables naturally co-vary, contrasting gradients should provide insights to disentangle their roles in biodiversity dynamics under a changing world. Therefore, this project takes advantage of 1) novel mechanistic models than can simulate contrasting environmental gradients and 2) a biological system of major ecological importance – vascular epiphytes. Vascular epiphytes, including most orchids and bromeliads, are plants growing non-parasitically on trees. They are key to nutrient cycles and interaction networks in tropical forests, accounting for 10% of world’s flora and up to 50% of some local floras. They vary in how they are distributed along vertical and elevational gradients, probably following their temperature and humidity preferences and often being geographically restricted (i.e. endemic and threatened). Epiphytes have been understudied due to difficulties in sampling the forest canopy despite being particularly vulnerable to deforestation and global warming. Hence, simulation experiments are ideal to improve our ecological understanding of the system while also to i) identify the data collection that should be prioritized in empirical studies and ii) explore scenarios of human impacts without manipulating vulnerable biodiversity.

General objective: To improve our understanding of natural biodiversity dynamics and biodiversity response to impending environmental change. Specific objectives: 1) Assess species’ vertical ranges at different elevations; 2) Identify the data requirements; 3) Explore the impact of interacting forest loss and global warming.

The image shows vascular epiphytes, illustrates the model’s spatial structure, flow diagram and emergent variables, and depict specific objectives.

Figure 1: Project study system, methods and experimental design. A) Vascular epiphytes on a tree, with the insert (top right) showing Cattleya intermedia – an orchid species occurring in the potential field site. B) Modelling approach (Petter et al. 2021): a 3-dimensional grid (top) in which the epiphytes undergo life-history processes constrained by their niche, competition for space as resource, disturbances (e.g. branchfall and treefall) and substrate availability (branch surface). C) Example of emergent patterns, such as vertical realized range of species (left) and overall abundance distribution (right) along the vertical gradient. D) Experimental design of the project: objective 1 (O1) – to describe how species change their vertical range along elevational gradients (top), objective 2 (O2) – to determine the data necessary to find the parameter values of the 3D model (bottom left), objective 3 (O3) – to explore how the vertical and elevational distribution of species will shift under synergetic effects of forest loss and global warming (bottom right).

CENTA Flagship

This is a CENTA Flagship Project


University of Birmingham


  • Climate and Environmental Sustainability
  • Organisms and Ecosystems


Project investigator

Dr. Juliano Sarmento Cabral, University of Birmingham ([email protected])


  • Dr. Diana Bowler, UKCEH – Biodiversity ([email protected])
  • Prof. Alexandre Antonelli, Director of Science, Royal Botanic Gardens Kew & University of Oxford ([email protected])

How to apply


Objective 1: We will apply a novel 3D individual-based model (Petter et al. 2021) that simulates epiphytes undergoing life-histories processes (Fig. 1B). Simulation scenarios will vary environmental conditions along elevation and assumptions about species’ niche characteristics. Emergent species’ ranges will be compared across the scenarios to assess interactive effects of local conditions and community dynamics (Fig. 1C-D).

Objective 2: We will apply the virtual ecologist approach (Zurell et al. 2010) by running optimization algorithms (e.g. DEoptim R package) on differently sampled simulated data to identify the best optimizer specifications and the minimal empirical requirements. Potential field work for validation may be done in the Brazilian Atlantic Rainforest.

Objective 3: We will simulate scenarios varying both the extent of forest loss and global warming (e.g. mitigation vs. business as usual). The results will provide insights about interactive effects between anthropogenic drivers and what species will be most vulnerable.

As the model is already developed (Petter et al 2021), the PhD candidate can concentrate at the beginning on learning and applying the model. Basic programming skills are necessary and will be further developed along the project. Field work is not necessary for the main planned activities, but can be included depending on how the project progresses, pandemic restrictions (if relevant), the candidate’s interests.

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.

The student will be trained in computational programming (e.g. R, Julia, Matlab), mechanistic models, optimization algorithms, handling and management of big data, collaborative working, modern computational methods. Further potential skills: field work in the tropics, tree climbing, data curation. Students providing evidence (e.g. via papers published in peer-review journals, course certificates and/or reference letters) for basic or advanced knowledge in computational skills will be preferred.

Partners and collaboration

The definition of detailed experimental design for describing vertical and elevational gradients (Objective 1) will be planned together with Prof. Antonelli (RBG Kew), whereas the development of the virtual ecologist optimizer and experimental design (Objective 2) will be planned together with Dr. Bowler (UK/CEH). Both Prof. Antonelli and Dr. Bowler will take part in the planning of the experimental design of environmental change scenarios (Objective 3). Potential field work and collection of field data will be planned with Prof. Antonelli in a newly established site (

Further details

Project investigator institutional details:

Dr. Juliano Sarmento Cabral:

Co-investigator institutional details:

Prof. Alexandre Antonelli:

Dr. Diana Bowler:

Potential field site:

If you wish to apply to the project, applications should include:

  • A CV with the names of at least two referees (preferably three and who can comment on your academic abilities)
  • Submit your application and complete the host institution application process via: and go to Apply Now in the PhD Bioscience (CENTA) section. Please quote CENTA23_B3 when completing the application form.

Applications to be received by the end of the day on Wednesday 11th January 2023. 

Additional information for international applicants

  • All international applicants must ensure they can fulfil the University of Birmingham’s international student entry requirements, which includes English language requirements.  For further information please visit
  • Please be aware that CENTA funding will only cover University fees at the level of support for Home-fee eligible students.  The University is only able to waive the difference on the international fee level for a maximum of two successful international applicants.

Possible timeline

Year 1

Learning model structure, development and application. Simulation experiments for describing vertical gradients along elevational gradients. Writing article #1.

Year 2

Learning and implementation of optimization methods. Design of a virtual ecologist (VE) experimental design. Potential field work for validating the VE approach. Writing article #2.

Year 3

Design of explorative scenarios of synergistically interacting forest loss and global warming. Potential field work for validating the VE approach. Writing article #3 and thesis.

Further reading

  • Bowler, D. E., Bjorkman, A., Dornelas, M., Myers-Smith, I., O’Connor, M., Navarro, L., Niamir, A., Supp, S., Waldock, C., Vellend, M., Blowes, S., Böhning-Gaese, K., Bruelheide, H., Elahi, R., Antão, L., Hines, J., Isbell, F., Jones, H., Magurran, A., Cabral, J., Winter, M., and Bates, A. (2020) ‘The geography of the Anthropocene differs between the land and the sea’, People and Nature, 2, pp. 380-394.
  • Cabral, J.S., Valente, L., and Hartig, F. (2017) ‘Mechanistic models in macroecology and biogeography: state-of-art and prospects’, Ecography, 40, pp. 267-280.
  • Hietz, P., Wagner, K., Nunes Ramos, F., Cabral, J., Agudelo, C., Benavides, A. M., Cach-Pérez, M. J., Cardelús, C., Chilpa Galván, N., Costa, L., de Paula Oliveira, R., Einzmann, H., Farias, R., Guzmán Jacob, V., Kattge, J., Kessler, M., Kirby, C., Kreft, H., Kromer, T., Males, J., Monsalve Correa, S., Moreno-Chacón, M., Petter, G., Reyes-Garcia, C., Saldana, A., Schellenberger Costa, D., Taylor, A., Velázquez Rosas, N.,  Wanek, W., Woods, C., and Zotz, G. (2021) ‘Putting vascular epiphytes on the traits map’, Journal of Ecology, 110, pp.340-358.
  • Pérez-Escobar, O.A., Zizka, A., Bermúdez, M.A., Meseguer, A.S., Condamine, F.L., Hoorn, C., Hooghiemstra, H., Pu, Y., Bogarín, D., Boschman, L.M., Pennington, R.T., Antonelli, A., and Chimicki, G.  (2022) ‘The Andes through time: evolution and distribution of Andean floras’. Trends in Plant Science, 27 (4), pp. 364-378.
  • Petter, G., Zotz, G., Kreft, H., Sarmento Cabral, J. (2021) ‘Modelling the effects of forest dynamics, selective logging and fragment size on structure and dynamics of epiphyte communities’, Ecology and Evolution, 11, pp. 2937–2951.
  • Sarmento Cabral, J., Jeltsch F., Midgley G.F., Higgins S.I., Phillips S.I., Rebelo A.G., Rouget M., Thuiller W., and Schurr F.M. (2013) ‘Impacts of past habitat loss and future climate change on the range dynamics of South African Proteaceae’, Diversity and Distributions, 19, pp. 363-376.
  • Zurell D., Berger U., Cabral J.S., Jeltsch F., Meynard C.N., Münkemüller T., Nehrbass N., Pagel J., Reineking B., Schröder B., and Grimm V. (2010) ‘The virtual ecologist approach: simulating data and observers’, Oikos, 119, pp. 622-635.


The work may be performed part-time from home office with adequate arrangements, as the planned work can be done entirely with computational methods. Therefore, typical restrictions of infection pandemic, such as lockdowns, will not affect the progress of the project. Potential field work may be subject to travel restrictions. However, if travel restrictions are too severe, field work can be excluded altogether without compromising the main objectives.