Overview
I am a PhD student at the University of Exeter funded by the NERC GW4+ DTP. I undertook my undergraduate degree in Biological Sciences at the University of Oxford, where I specialised in ecology and evolution. Following this degree, I completed my Master’s in Conservation and Biodiversity at the University of Exeter. My Master’s thesis investigated the effectiveness of electronic monitoring technologies in Peru’s small-scale elasmobranch fishery. Despite this, I have always been fascinated by tropical rainforests. My research now focuses on using plant eco-physiological traits to answer wider environmental and ecological questions. Through these techniques, I aim to understand the impacts of environmental change on wet tropical forests and how tropical trees respond to these changes across their different life history stages. I hope to improve the understanding of these hugely complex ecosystems and to help improve their long-term conservation.
Alongside my PhD research, I have developed many key skills attending courses on statistical modelling, programming and expedition planning. I have also taken an active role as a postgraduate teaching assistant, helping out on several modules including Biogeography and Ecosystems, Tropical Forests in a Changing World and Climate Change and its Impacts. I additionally have acted as an essay mentor for undergraduate students. I have been awarded postgraduate fellowship of the Royal Geographical Society. I also have been involved in setting up a series of public outreach talks, inviting field researchers to share their behind the scenes stories to the wider Exeter community.
Broad research specialisms:
Tropical Forests, Climate Change, Eco-Physiology, Water Dynamics, Carbon Dynamics.
Qualifications
BA (Hons) Biological Sciences 2015, University of Oxford, 1st class
MSc Conservation & Biodiversity 2016, University of Exeter, Distinction with Dean’s commendation
Research group links
Research
Research projects
Project Title:
What eco-physiological traits will facilitate survival in tropical forest trees under environmental change?
Supervisors:
Dr Lucy Rowland, Dr Lina Mercado, Dr Lindsay Banin (Edinburgh CEH), Prof David Burslem (University of Aberdeen)
Funding Body:
NERC
Project Description:
My research involves investigating how tropical forest trees adapt and respond to environmental stress under a changing climate. In particular, I am interested in understanding how shifts in water, nutrient and light availability affect growth and survival rates. I utilise a range of metabolic and hydrological eco-physiology traits to answer wider ecological questions about the responses of tropical forests to environmental change. My research focuses on both experimental and natural gradients in soil moisture and nutrients across the tropics. The world’s longest running tropical drought experiment in Caxiuanã, Para State, Brazil, is the focal experimental site for my research. Here, 50% of the rainfall has been excluded from a 1 ha plot through the use of plastic panels since 2002. This site allows me to understand how trees of different ages are responding to rapid changes in water availability. In order to identify longer term adaptations to extreme water and nutrient environments, I will utilise a natural water-nutrient gradient in the Sepilok Forest Reserve, Sabah, Malaysia. This site has three distinct forest types, ranging from the nutrient-rich, flood-prone alluvial forest, to the dry, nutrient-poor kerangas forest, with an intermediate terra firme forest. Each of these forests are dominated by the Dipterocarpaceae family. This important family is the focus of my research into long-term adaptations to environmental stress. My key research questions concern understanding how traits differ between habitat specialists and generalists and how they change with ontogenetic development. Overall, I hope to understand how tropical forests will respond to environmental change.
Publications:
Bartholomew, D.C., Bittencourt, P.R.L., da Costa, A.C.L., Banin, L.F., Brito Costa, P., Coughlin, S.I., Domingues, T.F., Ferreira, L.V., Giles, A., Mencuccini, M., Mercado, L., Miatto, R.C., Oliveira, A., Oliveira, R., Meir, P. and Rowland, L. (2020), Small tropical forest trees have a greater capacity to adjust carbon metabolism to long‐term drought than large canopy trees. Plant Cell Environ. Accepted Author Manuscript. doi:10.1111/pce.13838
Bittencourt, PRL, Oliveira, RS, da Costa, ACL, et al. Amazonia trees have limited capacity to acclimate plant hydraulic properties in response to long‐term drought. Glob Change Biol. 2020; 26: 3569– 3584. https://doi.org/10.1111/gcb.15040
Bartholomew, D.C., Mangel, J.C., Alfaro-Shigueto, J., Pingo, S., Jimenez, A. and Godley, B.J., 2018. Remote electronic monitoring as a potential alternative to on-board observers in small-scale fisheries. Biological Conservation, 219, pp.35-45. https://doi.org/10.1016/j.biocon.2018.01.003
Williams, HF, Bartholomew, DC, Amakobe, B, Githiru, M. Environmental factors affecting the distribution of African elephants in the Kasigau wildlife corridor, SE Kenya. Afr J Ecol. 2018; 56: 244– 253. https://doi.org/10.1111/aje.12442
Publications
Key publications | Publications by category | Publications by year
Publications by category
Journal articles
Bartholomew DC, Banin LF, Bittencourt PRL, Suis MAF, Mercado LM, Nilus R, Burslem DFRP, Rowland L (2022). Differential nutrient limitation and tree height control leaf physiology, supporting niche partitioning in tropical dipterocarp forests. Functional Ecology
Barstow M, Bartholomew D (2022). Launch of situational crime prevention toolkit to address illegal wildlife trade.
ORYX,
56(1), 9-10.
Author URL.
Bittencourt PRL, Oliveira RS, Costa ACL, Giles AL, Coughlin I, Costa PB, Bartholomew DC, Ferreira LV, Vasconcelos SS, Barros FV, et al (2020). Amazonia trees have limited capacity to acclimate plant hydraulic properties in response to long‐term drought. Global Change Biology, 26(6), 3569-3584.
Bartholomew DC, Bittencourt PRL, da Costa ACL, Banin LF, de Britto Costa P, Coughlin SI, Domingues TF, Ferreira LV, Giles A, Mencuccini M, et al (2020). Small tropical forest trees have a greater capacity to adjust carbon metabolism to long-term drought than large canopy trees.
Plant Cell Environ,
43(10), 2380-2393.
Abstract:
Small tropical forest trees have a greater capacity to adjust carbon metabolism to long-term drought than large canopy trees.
The response of small understory trees to long-term drought is vital in determining the future composition, carbon stocks and dynamics of tropical forests. Long-term drought is, however, also likely to expose understory trees to increased light availability driven by drought-induced mortality. Relatively little is known about the potential for understory trees to adjust their physiology to both decreasing water and increasing light availability. We analysed data on maximum photosynthetic capacity (Jmax , Vcmax ), leaf respiration (Rleaf ), leaf mass per area (LMA), leaf thickness and leaf nitrogen and phosphorus concentrations from 66 small trees across 12 common genera at the world's longest running tropical rainfall exclusion experiment and compared responses to those from 61 surviving canopy trees. Small trees increased Jmax , Vcmax , Rleaf and LMA (71, 29, 32, 15% respectively) in response to the drought treatment, but leaf thickness and leaf nutrient concentrations did not change. Small trees were significantly more responsive than large canopy trees to the drought treatment, suggesting greater phenotypic plasticity and resilience to prolonged drought, although differences among taxa were observed. Our results highlight that small tropical trees have greater capacity to respond to ecosystem level changes and have the potential to regenerate resilient forests following future droughts.
Abstract.
Author URL.
Rowland L, Costa ACL, Oliveira RS, Bittencourt PRL, Giles AL, Coughlin I, Britto Costa P, Bartholomew D, Domingues TF, Miatto RC, et al (2020). The response of carbon assimilation and storage to long‐term drought in tropical trees is dependent on light availability. Functional Ecology, 35(1), 43-53.
Williams HF, Bartholomew DC, Amakobe B, Githiru M (2018). Environmental factors affecting the distribution of African elephants in the Kasigau wildlife corridor, SE Kenya.
African Journal of Ecology,
56(2), 244-253.
Abstract:
Environmental factors affecting the distribution of African elephants in the Kasigau wildlife corridor, SE Kenya
The African elephant, Loxodonta africana, is under threat from habitat loss, poaching and human–elephant conflict. To mitigate for impact of habitat loss and reduce conflict, connectivity between elephant habitats can be improved through the protection of corridor areas. This study looks at elephant distribution and movement patterns within the Kasigau Wildlife Corridor (KWC) within the Tsavo Conservation Area in South-east Kenya. Elephant presence data were obtained from observations by rangers during routine patrols across KWC, and were analysed in MaxEnt. The environmental factors predicting elephant distribution and density were tested, as well as the relationship between elephant maximum entropy and the presence and abundance of other wildlife. Seasonal variations in temperature and precipitation, plus presence of waterholes were found to play significant roles in elephant distribution across KWC. Higher elephant densities were not found to correlate with lower densities of other wildlife species; indeed, during the dry seasons, elephant presence was associated with greater wild herbivore densities. Besides illustrating the importance of the KWC for elephant conservation in the Tsavo ecosystem, both as a key corridor and habitat, this study also hopes to highlight the untapped utility of routine ranger patrol data, and encourage the use of such presence-only data for deducing important knowledge for conservation of biodiversity.
Abstract.
Bartholomew DC, Mangel JC, Alfaro-Shigueto J, Pingo S, Jimenez A, Godley BJ (2018). Remote electronic monitoring as a potential alternative to on-board observers in small-scale fisheries. Biological Conservation, 219, 35-45.
Publications by year
2022
Bartholomew DC, Banin LF, Bittencourt PRL, Suis MAF, Mercado LM, Nilus R, Burslem DFRP, Rowland L (2022). Differential nutrient limitation and tree height control leaf physiology, supporting niche partitioning in tropical dipterocarp forests. Functional Ecology
Barstow M, Bartholomew D (2022). Launch of situational crime prevention toolkit to address illegal wildlife trade.
ORYX,
56(1), 9-10.
Author URL.
2021
Bartholomew D (2021). Tree Function and Habitat Niche Partitioning in Tropical Forests:
Implications for Responses to Environmental Change.
Abstract:
Tree Function and Habitat Niche Partitioning in Tropical Forests:
Implications for Responses to Environmental Change
Tropical forests possess exceptional levels of tree species richness but explaining this diversity has presented a long existing challenge. Habitat niche partitioning provides a hypothesis for species co-existence, whereby species avoid competitive exclusion by partitioning demands on multiple resources within an environment. However, limited understanding concerning how tree function is influenced by multiple environmental variables has limited the support for this hypothesis. This knowledge gap also limits our ability to predict how tropical forest tree communities will respond to environmental change, given multiple dimensions of a species’ niche are likely to be affected.
In this thesis, I investigate the role of niche partitioning in supporting co-existence of species and the turnover of species across edaphic gradients, as well as how long-term changes to the environment from selective logging and drought affect niche space of tropical tree species. I use species distribution models and measurements of leaf physiological traits to determine the key dimensions of tree species’ niches in primary forests.
In chapter 2 I demonstrate niche partitioning is strong within tropical forests with at least 60-86% of abundant species occupying their own unique niche. Species partition a wide range of abiotic environments, including soil nutrient, topographic and light environments, with greater environmental heterogeneity enhancing the scope for niche partitioning. Building on this, in chapter 3 I find that variation in nutrient availability explains more variation in leaf physiology and habitat preferences than light availability of species from the Dipterocarpaceae family that dominates South-East Asian forests. This highlights the importance of edaphic environments in structuring tropical forest communities. I also find different leaf nutrients are related to photosynthetic capacity in different forest types, revealing that multiple different nutrients may limit productivity and affect species distributions in tropical forests.
Many tropical forest tree species are highly specialised with limited ability to adjust their traits between environments, underlining their potential vulnerability to environmental change. In chapter 4 I show seedlings from selectively logged Bornean forests have different community weighted mean trait values, with greater belowground investment in logged forests. These adaptations are sufficient to overcome soil stress and to maintain foliar nutrient concentrations. However, I show seedlings of species that dominate old-growth forests are less able to adapt their traits and experience elevated mortality rates in logged forests. I attribute this to greater soil nutrient limitation as they are unable to maintain leaf nutrient concentrations. Selective logging will therefore likely drive shifts in species composition towards greater dominance of earlier-successional species that have traits capable of surviving in disturbed environments. This could result in local-scale reductions in species diversity and functional diversity, which could reduce long-term resilience to environmental change. In contrast, in Chapter 5 I demonstrate small trees in Amazonian forests are able to respond to changes in their environment following long-term drought conditions. Following mortality of large canopy trees, small trees can respond to increased light availability even under reduced water availability by adjusting resource allocation and by increasing nutrient use efficiency. Despite evidence of resilience to long-term drought conditions, hyper-dominant species show a greater capacity to respond, which may further enhance the dominance of these species under future climates.
In conclusion my results highlight the importance of habitat niche partitioning in structuring tropical forest tree communities and identify key environmental variables that determine species distribution and tree function. My results have important implications for the conservation and restoration of tropical forests under environmental change. Avoidance of environmental homogenisation and changes to as few environmental conditions as possible is likely to be important in maintaining high species diversity in tropical forests and to avoid increased dominance by few generalist species. Many current conservation and restoration projects focus on recovering vegetation, but my research highlights the additional need to maintain and restore soil environments, especially for the long-term persistence of highly specialist species.
Abstract.
2020
Bittencourt PRL, Oliveira RS, Costa ACL, Giles AL, Coughlin I, Costa PB, Bartholomew DC, Ferreira LV, Vasconcelos SS, Barros FV, et al (2020). Amazonia trees have limited capacity to acclimate plant hydraulic properties in response to long‐term drought. Global Change Biology, 26(6), 3569-3584.
Bartholomew DC, Bittencourt PRL, da Costa ACL, Banin LF, de Britto Costa P, Coughlin SI, Domingues TF, Ferreira LV, Giles A, Mencuccini M, et al (2020). Small tropical forest trees have a greater capacity to adjust carbon metabolism to long-term drought than large canopy trees.
Plant Cell Environ,
43(10), 2380-2393.
Abstract:
Small tropical forest trees have a greater capacity to adjust carbon metabolism to long-term drought than large canopy trees.
The response of small understory trees to long-term drought is vital in determining the future composition, carbon stocks and dynamics of tropical forests. Long-term drought is, however, also likely to expose understory trees to increased light availability driven by drought-induced mortality. Relatively little is known about the potential for understory trees to adjust their physiology to both decreasing water and increasing light availability. We analysed data on maximum photosynthetic capacity (Jmax , Vcmax ), leaf respiration (Rleaf ), leaf mass per area (LMA), leaf thickness and leaf nitrogen and phosphorus concentrations from 66 small trees across 12 common genera at the world's longest running tropical rainfall exclusion experiment and compared responses to those from 61 surviving canopy trees. Small trees increased Jmax , Vcmax , Rleaf and LMA (71, 29, 32, 15% respectively) in response to the drought treatment, but leaf thickness and leaf nutrient concentrations did not change. Small trees were significantly more responsive than large canopy trees to the drought treatment, suggesting greater phenotypic plasticity and resilience to prolonged drought, although differences among taxa were observed. Our results highlight that small tropical trees have greater capacity to respond to ecosystem level changes and have the potential to regenerate resilient forests following future droughts.
Abstract.
Author URL.
Rowland L, Costa ACL, Oliveira RS, Bittencourt PRL, Giles AL, Coughlin I, Britto Costa P, Bartholomew D, Domingues TF, Miatto RC, et al (2020). The response of carbon assimilation and storage to long‐term drought in tropical trees is dependent on light availability. Functional Ecology, 35(1), 43-53.
2018
Williams HF, Bartholomew DC, Amakobe B, Githiru M (2018). Environmental factors affecting the distribution of African elephants in the Kasigau wildlife corridor, SE Kenya.
African Journal of Ecology,
56(2), 244-253.
Abstract:
Environmental factors affecting the distribution of African elephants in the Kasigau wildlife corridor, SE Kenya
The African elephant, Loxodonta africana, is under threat from habitat loss, poaching and human–elephant conflict. To mitigate for impact of habitat loss and reduce conflict, connectivity between elephant habitats can be improved through the protection of corridor areas. This study looks at elephant distribution and movement patterns within the Kasigau Wildlife Corridor (KWC) within the Tsavo Conservation Area in South-east Kenya. Elephant presence data were obtained from observations by rangers during routine patrols across KWC, and were analysed in MaxEnt. The environmental factors predicting elephant distribution and density were tested, as well as the relationship between elephant maximum entropy and the presence and abundance of other wildlife. Seasonal variations in temperature and precipitation, plus presence of waterholes were found to play significant roles in elephant distribution across KWC. Higher elephant densities were not found to correlate with lower densities of other wildlife species; indeed, during the dry seasons, elephant presence was associated with greater wild herbivore densities. Besides illustrating the importance of the KWC for elephant conservation in the Tsavo ecosystem, both as a key corridor and habitat, this study also hopes to highlight the untapped utility of routine ranger patrol data, and encourage the use of such presence-only data for deducing important knowledge for conservation of biodiversity.
Abstract.
Bartholomew DC, Mangel JC, Alfaro-Shigueto J, Pingo S, Jimenez A, Godley BJ (2018). Remote electronic monitoring as a potential alternative to on-board observers in small-scale fisheries. Biological Conservation, 219, 35-45.
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