Research

BioResilience | Amazon Past Fire | Exeter Carbon Observatory | Grants

Research interests

Research focusses on a range of topics including tropical forest ecology;  land-cover, land-use change; forest disturbance, degradation, and recovery; logging; forest-climate interactions; drought; fire; terrestrial carbon and nutrient cycling; soil water use. My research team uses approaches such as long-term vegetation monitoring, selective logging and nutrient manipulation field experiments, lidar, radar, charcoal reflectance, anthracological analysis, natural and experimental forest burning, soil and vegetation isotopes, and pyrogenic carbon analysis.

Postdoctoral opportunities

 

Research Projects

Biodiversity resilience and ecosystem services in post-conflict socio-ecological systems

The BioResilience project examines the long-term resilience of Colombian forest ecosystems to environmental and climatic changes and to improve understanding of the future implications of forest degradation for Colombian society (PI Feldpausch; NERC/AHRC NE/R017980/1). This fills a research gap in understanding how forests, which may be regarded as biologically ‘degraded’, have undergone changes in biodiversity, in ecosystem services, and in how they participate in local and global cycles of carbon and energy. The project will evaluate biodiversity and current and historical effects of fire, and carbon storage and changing climate. These data will be integrated with socio-cultural research, focusing on existing cultures of biodiversity conservation. This understanding is essential if the scientific evidence is to be integrated into long-term management plans and policy, as forest degradation in Colombia is strongly associated with changes to the fabric of social life, including the effects of sustained conflict. The project aims to transform understanding of the controls on forest biodiversity and ecosystem service, determine ecosystem resilience to climate and disturbance, and support socio-environmental planning for sustainable resource use. More info at the BioResilience project website.

Fire effects on tropical forests: past, present, future

While deforestation has declined in some tropical areas, forests are undergoing an increase in the number and area of fires. There is large uncertainty about how fire affects forests and the degree to which historical fires have contributed to the formation of modern forests. I currently coordinate two projects evaluating the effects of fire on tropical forests at two time scales: historical fires (over hundreds to thousands of years) and modern fires (within the last few decades).

Historical fire: Under a three-year project (PI Feldpausch; NERC NE/N011570/1), we are evaluating the extent of past fires in Amazonia, including the chronology, contribution to soil pyrogenic carbon storage and the isotopic signature of past fires to evaluate whether past fires have legacy effects on the composition, structure, and dynamics of modern forests. The results will have significant impacts in predicting the future magnitude and longevity of the Amazon carbon sink, understanding long-term fire effects, redirecting conservation practices, improving vegetation models, and affecting policy such as REDD+. More info at the Amazon Fire project website.

Modern fires: Using a combination of ground-based measurements, airborne lidar, and radar data, we are quantifying how human-induced disturbances affect the uptake and release of carbon in degraded Amazon forests across the basin-wide degradation frontier (Feldpausch, SilvaCarbon Fund). We are evaluating how logging and fire disturbance modifies forest structure and species composition, and whether these changes alter trajectories of degradation and/or recovery, and forest resilience to disturbance.

Lightning: An invisible driver of tree mortality in the tropics?

This project aims to determine the rate of lightning-induced tree mortality in the tropics (PI T.Hill, coI Feldpausch; NERC NE/P001564/1). Currently, it is known that some large trees in the tropic have been killed by lightning, and it is also known that lightning strikes in the tropics probably strike trees with up to ~ 1 % of forest biomass each year. Therefore lightning could have a major influence on forest dynamics. As lightning rates increase with climate warming, the strength of the terrestrial carbon sink may even be reduced.  Despite the potential significance of lightning in the tropics, there have been almost no studies on the interaction between lightning and trees in the tropics. As a consequence, estimates on the rates of lightning-induced tree mortality and subsequent lightning-driven forest carbon dynamics simply do not exist.  We will perform the world’s first systematic observations of lightning-induced mortality through the large-scale deployment of novel lightning strike sensors to quantify the number of trees struck and killed by lightning over a 4 year period. This approach will allow us to address a major question of the 21st century about drivers of tree mortality in the tropics, and the resultant effect on the tropical land carbon sink.

Exeter Carbon Observatory

The Exeter Carbon Observatory (ExCO) is an open-air ecosystem laboratory, designed by researchers from the College of Life and Environmental Sciences at the University of Exeter, and funded by the University of Exeter’s Annual Fund. This initiative aims to allow students, academics and wider society to explore and learn about the role that terrestrial ecosystems play in removing carbon dioxide from the atmosphere and the effects of climate change on the stability of carbon uptake and storage in these systems. More info at the ExCO website.

 

Improving estimates of global aboveground biomass

How trees develop height and crown structure can affect carbon capture, response to environmental changes, and competition for light. For example, drought response by trees and mortality from fire may be affected by the shape, size, and spatial arrangement of trees in forests. This project evaluates the drivers of variation in pantropical tree height and crown allometry and biomass in forests across South America, Africa, SE Asia, and Australia. The results will have important implications for forest management and Dynamic Global Vegetation models.

Amazon Secondary Forest Fertilization Experiment

Tropical forest degradation and regrowth is potentially a first-order component of human influence on the carbon cycle but is poorly understood. This project works to improve understanding of forest degradation, nutrient limitations and implications for forest C sinks (PI Feldpausch). To date, most research on the role of tropical forests in the global C cycle has focused on “intact” forests and deforestation, with very limited emphasis on degradation and secondary forest regrowth. Previous land-use intensity and nutrient limitations may affect the rate of C sequestration in regrowing forests by resulting in nutrient loss via burning, erosion, and leaching. While CO2 fertilization may increase the terrestrial C sink, nutrient limitations may place limits on the magnitude of this effect, because tropical forest soils are acidic and nutrient impoverished, especially in P. However, almost nothing is known about how nutrient limitations such as P and Ca affect regrowing tropical forest vegetation, soil moisture dynamics, and response to drought. This project employs a long-term secondary forest fertilization experiment (15+ years) to address these knowledge gaps.

Drought and tropical forests

This work evaluates how long-term and more recent changes in climate affect the composition and function of tropical forests. Shifts in species composition due to mortality from drought may have important implications on the Amazon carbon sink and ecosystem services. Approaches used in this project to evaluate change include the use of long-term forest inventory data on forest composition and dynamics spanning decades and remote sensing such as lidar and radar.

Peat and past fire in Amazonian forests

Amazonian rainforests and peatlands are the largest terrestrial tropical carbon (C) pool undergoing rapid change. Tropical peatlands have relatively well-preserved stratigraphies not found in mineral soils. The stratigraphy of these systems can be used to understand past pyrogenic carbon (PyC, a recalcitrant form of C formed by burning) inputs and their sources. There is large uncertainty about the quantity of soil C stored as PyC and the contribution of local versus transported PyC. Our research has indicated that Amazonian soil PyC may be 10 times larger than previously estimated (Koele et al. 2017). Yet, there is essentially no information about how or when PyC additions to mineral or peatland soils have occurred. Understanding this process and the historical changes to this potential fertility source is essential to understanding drivers of the Amazon carbon sink. The peatlands of western Amazonia combined with our basin-wide PyC estimates provide a unique opportunity to address these data gaps. The aims of this project are to improve understanding of sources and timing of past fire and soil PyC over hundreds to thousands of years in Amazonia and quantifies the contribution of PyC to the total rainforest carbon pool and sink.