Umbrella species in conservation: elephants as ecosystem engineers
Elephants are umbrella species, thus ensuring that elephant habitat and resources are conserved can benefit many other species, contributing to biodiversity conservation. Elephants are also key ecosystem engineers that shape and maintain ecosystems through their diet, movement, and disturbance, affecting forest structure, carbon storage, and biodiversity. My research explores dynamic links between wildlife behavior and ecosystem function and integrity.
Elephant foraging for fruit in Wonga Wongue, Gabon. Photo courtesy of Liam Jasperse-Sjolander.
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One of my research interests is in how forest elephants influence Congo Basin forests. I led a study finding strong site-level variation in the species and traits of seeds dispersed by elephants (link). This context-dependency challenges assumptions of uniform elephant impacts in climate and biodiversity models, and reminds us that specificity is key when incorporating wildlife into monitoring strategies for carbon and biodiversity conservation and policy. Additionally, I have conducted on research exploring how elephant foraging around fruit trees influences understory forest structure and diversity in the Congo Basin (link), .
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During my PhD, I examined how plant-animal interactions shape regeneration in selectively logged tropical forests. I found that saplings with animal-dispersed seeds were more prevalent in older logged forests than in unlogged forests (link), suggesting that best-practice low intensity logging doesn't disrupt animal dispersal processes in these forests. Additionally, I found that seedling survival was lower on forest elephant trails in the understory of both logged and unlogged forests in Gabon (link), indicating there are trade-offs between seed dispersal and seedling establishment in high elephant activity areas.
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.Seedlings sprouting in an elephant dung pile in a forest in the Monts de Cristal landscape in Gabon.
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Monitoring biodiversity & ecosystem functioning
Understanding how ecosystems function and recover is essential for evidence-based conservation. Through my work, I develop and apply biodiversity and monitoring frameworks in collaboration with conservation practitioners and industry collaborators to generate evidence that informs restoration and sustainable management strategies.
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As a Fulbright Scholar in Rwanda, I partnered with the Centre of Excellence in Biodiversity and Natural Resource Management (CoEB) at the University of Rwanda and collaborated with diverse in-country stakeholders to conduct climate change-relevant research that informs restoration strategies. My role involved capacity building to support the development of biodiversity and ecological monitoring and evaluation in collaboration with local partners. Through several different projects, I conducted trainings and workshops in research project design and implementation, quantitative analyses, report writing, publication writing, and science communication.
Our team from CoEB is currently working on publishing results from baseline biodiversity surveys that conducted for the Community-Based Biodiversity Conservation (COMBIO) project -- the biodiversity component to the Transforming Eastern Province Through Adaptation (TREPA) project. |
A buffer zone surrounding a dam — one of seven land-use types surveyed in the Eastern Province of Rwanda as a part of the COMBIO project.
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A cut tree in a logging concession in Gabon.
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Selective logging is often promoted as a land-use compromise -- one that allows timber extraction while maintaining ecological function. My work has explored how this widespread but localized disturbance influences forest recovery and resilience by evaluating forest structure, composition, and regeneration.
We found that very low-intensity selective logging in Gabon (removal of < 2 trees/ha) caused relatively small, short-term shifts in understory structure and diversity (link), and that logged forests had some composition differences compared to unlogged forests, but maintained key ecosystem services (link). Although seedling dynamics were initially affected for several years after logging, most impacts disappeared within 14 years (link). Overall, the results of this work suggest that that well-managed, very low-intensity selective logging can be contribute towards sustainably managed forest across a mixed-use landscape, and may be able to extend conservation estate via corridors and as as mixed-use conservation areas. |
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Small and community-managed forests can play an outsized role in conserving biodiversity. Sacred forests -- protected for their cultural and spiritual value -- often serve as refuges for species in fragmented landscapes. Yet their ecological importance is frequently overlooked. Our meta-analysis comparing sacred and non-sacred forests (link) found that sacred forests harbor similar levels of biodiversity, highlighting that cultural protection can be as effective as formal conservation.
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Countries with sacred forest biodiversity comparison data used in a global meta-analysis.
From Sullivan et al. 2024. |
Environmental variation shapes plant communities
A key challenge in ecology is understanding how environmental variation shapes plant communities and drives ecosystem change. My research explores how plants respond to shifting environmental conditions -- from changes in rainfall and temperature to elevation and disturbance -- and what these shifts mean for biodiversity, ecosystem function, and resilience. I explore these questions across multiple scales, ecosystems, and regions.
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I led a review synthesizing research on tropical tree reproductive phenology (the timing of flowering and fruiting in tree species) and how shifts in phenological patterns can have cascading impacts in tropical ecosystems. Shifts in fruiting patterns can alter the reproductive success of tree species and also affect resource availability for wildlife populations, creating challenges for the management and conservation of tropical forest ecosystems (link).
Building on this synthesis, I analyzed more than two decades of fruit phenology data from Nyungwe National Park in Rwanda, and found that there was a gradual increase in fruit production over time in this high-elevation forest ecosystem (link). This is the opposite of the pattern previously found in studies in lowland forests, where precipitous declines in fruit production have been reported. These results highlight that climate impacts on tropical forests are not uniform, and that local context strongly shapes ecosystem responses to global change. |
Phenology monitoring at the Ipassa Research Station, Ivindo NP, Gabon.
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Plant functional trait sampling on an elevational gradient in the Gongga Mountains, China.
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In other projects, I've studied how plant traits vary across climatic gradients to understand adaptive strategies and community assembly. In the Brazilian cerrado, I examined macroecological patterns of leaf trait variation across precipitation and temperature gradients. Our study explored how drip-tip incidence in Cerrado species is affected by climate and species distribution patterns (link). Additionally, I assisted in amassing a dataset of herbaceous plant traits across a climate & elevation gradient in the Gongga Mountains, Sichuan, China (link). Together, these studies reveal how environmental variation -- from rainfall to elevation -- shapes plant strategies and ecosystem function across tropical ecosystem.
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