Papers by Elizabeth Jeffers
Water, 2021
With widespread, long-term historical use of plastics and the presence of microplastics in a rang... more With widespread, long-term historical use of plastics and the presence of microplastics in a range of new and existing products, there is rising concern about their potential impacts on freshwater ecosystems. Understanding how microplastics are transported and distributed along river systems is key to assessing impacts. Modelling the main flow dynamics, mixing, sedimentation and resuspension processes is essential for an understanding of the transport processes. We use the new, processed based, dynamic, integrated catchments (INCA) microplastics model and apply this to the whole of the freshwater catchment of the River Thames, UK, to evaluate inputs, loads and concentrations along the river system. Recent data from UK water industry studies on microplastics in effluent discharges and sewage sludge disposal has been utilised to drive the INCA microplastics model. Predicted concentrations and microplastic loads moving along the river system are shown to be significant, with a build-up...
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Frontiers of Biogeography, 2013
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New Phytologist, 2021
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A B S T R A C T Humanity faces a major global challenge in achieving wellbeing for all, while sim... more A B S T R A C T Humanity faces a major global challenge in achieving wellbeing for all, while simultaneously ensuring that the biophysical processes and ecosystem services that underpin wellbeing are exploited within scientifically informed boundaries of sustainability. We propose a framework for defining the safe and just operating space for humanity that integrates social wellbeing into the original planetary boundaries concept (Rockströ m et al., 2009a,b) for application at regional scales. We argue that such a framework can: (1) increase the policy impact of the boundaries concept as most governance takes place at the regional rather than planetary scale; (2) contribute to the understanding and dissemination of complexity thinking throughout governance and policy-making; (3) act as a powerful metaphor and communication tool for regional equity and sustainability. We demonstrate the approach in two rural Chinese localities where we define the safe and just operating space that lies between an environmental ceiling and a social foundation from analysis of time series drawn from monitored and palaeoecological data, and from social survey statistics respectively. Agricultural intensification has led to poverty reduction, though not eradicated it, but at the expense of environmental degradation. Currently, the environmental ceiling is exceeded for degraded water quality at both localities even though the least well-met social standards are for available piped water and sanitation. The conjunction of these social needs and environmental constraints around the issue of water access and quality illustrates the broader value of the safe and just operating space approach for sustainable development.
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Whilst there are a number of mapping methods available for determining important areas for conser... more Whilst there are a number of mapping methods available for determining important areas for conservation within protected areas, there are few tools available for assessing the ecological value of landscapes that are ‘beyond the reserves’. A systematic tool for determining the ecological value of landscapes outside of protected areas could be relevant to any development that results in a parcel of land being transformed from its ‘natural’ state to an alternative state (e.g., industrial, agricultural). Specifically what is needed is a method to determine which landscapes beyond protected areas are important for the ecological processes that they support and the threatened and vulnerable species that they contain. This paper presents the results of a project to develop a method for mapping ecologically important landscapes beyond protected areas; a Local Ecological Footprinting Tool (LEFT). The method uses existing globally available web-based databases and models to provide an ecological score based on five key ecological features (biodiversity, vulnerability, fragmentation, connectivity and resilience) for every 300 m parcel within a given region. The end product is a map indicating ecological value across the landscape. We demonstrate the potential of this method through its application to three study regions in Canada, Algeria and the Russian Federation. The primary audience of this tool are those practitioners involved in planning the location of any landscape scale industrial/business or urban (e.g., new town) facility outside of protected areas. It provides a pre-planning tool, for use before undertaking a more costly field-based environmental impact assessment, and quickly highlights areas of high ecological value to avoid in the location of facilities.
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The extent to which plants exert an influence over ecosystem processes, such as nitrogen cycling ... more The extent to which plants exert an influence over ecosystem processes, such as nitrogen cycling and fire regimes, is still largely unknown. It is also unclear how such processes may be dependent on the prevailing environmental conditions.
Here, we applied mechanistic models of plant–environment interactions to palaeoecological time series data to determine the most likely functional relationships of Empetrum (crowberry) and Betula (birch) with millennial-scale changes in climate, fire activity, nitrogen cycling and herbivore density in an Irish heathland.
Herbivory and fire activity preferentially removed Betula from the landscape. Empetrum had a positive feedback on fire activity, but the effect of Betula was slightly negative. Nitrogen cycling was not strongly controlled by plant population dynamics. Betula had a greater temperature-dependent population growth rate than Empetrum; thus climate warming promoted Betula expansion into the heathland and this led to reduced fire activity and greater herbivory, which further reinforced Betula dominance.
Differences in population growth response to warming were responsible for an observed shift to an alternative community state with contrasting forms of ecosystem functioning. Self-reinforcing feedback mechanisms – which often protect plant communities from invasion – may therefore be sensitive to climate warming, particularly in arctic regions that are dominated by cold-adapted plant populations.
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1. Plant–plant interactions are known to vary with changing environmental conditions; however, we... more 1. Plant–plant interactions are known to vary with changing environmental conditions; however, we have little empirical knowledge of the impact of abrupt environmental changes on millennial scale plant–plant interaction outcomes for long-lived plant species. Here, we used palaeoecological data (13–7.6 k years bp) and a novel statistical modelling approach to determine the impact of multiple environmental drivers on predicted tree–grass population interaction outcomes from our study site in eastern England.
2. Changes from high to low herbivore density shortly preceded changes to low fire levels and a shift to warmer summers. These transitions occurred during a period of increasing nitrogen (N) availability. Shortly thereafter, there was a shift in landscape dominance from grasses to oaks and then a change to decreasing N availability.
3. Model predictions of tree–grass interaction outcomes varied over time with respect to all environmental changes. During the time of high disturbances and cool summers, grasses were predicted to out-compete oaks. After climate warming and the loss of regular disturbances, the predicted outcome was stable coexistence. However, changes in the N cycle corresponded with different predicted outcomes: unstable competition under increasing N availability and facilitation of oaks by grasses when N availability was declining.
4. Akaike Information Criterion weights indicate that climate warming and fewer fires were consistent with the best-fitting model of oak–grass interactions for the entire time series (i.e. competitive exclusion to stable coexistence). However, reconciling the conflicting model predictions with the observed population dynamics suggests that a temporary period of unstable competition preceded the predicted shift to stable coexistence. This dynamic behaviour is consistent with known patterns of shifts between alternative stable states.
5. Synthesis. We show that abrupt changes in environmental conditions over time lead to similarly abrupt changes in tree–grass interaction outcomes, which were shown to vary in contrasting directions with respect to resource versus non-resource variables. The approach described here allows plant ecologists to test hypotheses of plant–plant interactions over successional time scales for long-lived species and thus can lead to new knowledge about the structural role of these interactions in community dynamics.
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Classical ecological theory predicts that changes in the availability of essential resources such... more Classical ecological theory predicts that changes in the availability of essential resources such as nitrogen should lead to
changes in plant community composition due to differences in species-specific nutrient requirements. What remains
unknown, however, is the extent to which climate change will alter the relationship between plant communities and the
nitrogen cycle. During intervals of climate change, do changes in nitrogen cycling lead to vegetation change or do changes
in community composition alter the nitrogen dynamics? We used long-term ecological data to determine the role of
nitrogen availability in changes of forest species composition under a rapidly changing climate during the early Holocene
(16k to 8k cal. yrs. BP). A statistical computational analysis of ecological data spanning 8,000 years showed that secondary
succession from a coniferous to deciduous forest occurred independently of changes in the nitrogen cycle. As oak replaced
pine under a warming climate, nitrogen cycling rates increased. Interestingly, the mechanism by which the species
interacted with nitrogen remained stable across this threshold change in climate and in the dominant tree species. This
suggests that changes in tree population density over successional time scales are not driven by nitrogen availability. Thus, current models of forest succession that incorporate the effects of available nitrogen may be over-estimating tree
population responses to changes in this resource, which may result in biased predictions of future forest dynamics under
climate warming.
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The 95th ESA Annual Meeting, Jan 1, 2010
Tuesday, August 3, 2010 - 4:00 PM Fire and flammability characteristics in community dynamics: In... more Tuesday, August 3, 2010 - 4:00 PM Fire and flammability characteristics in community dynamics: Inferring feedback mechanisms from the palaeoecological record. Elizabeth S. Jeffers, University of Oxford, Michael Bonsall, University ...
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Recent and Most-Cited Papers by Elizabeth Jeffers
Ecology Letters, 2016
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Papers by Elizabeth Jeffers
Here, we applied mechanistic models of plant–environment interactions to palaeoecological time series data to determine the most likely functional relationships of Empetrum (crowberry) and Betula (birch) with millennial-scale changes in climate, fire activity, nitrogen cycling and herbivore density in an Irish heathland.
Herbivory and fire activity preferentially removed Betula from the landscape. Empetrum had a positive feedback on fire activity, but the effect of Betula was slightly negative. Nitrogen cycling was not strongly controlled by plant population dynamics. Betula had a greater temperature-dependent population growth rate than Empetrum; thus climate warming promoted Betula expansion into the heathland and this led to reduced fire activity and greater herbivory, which further reinforced Betula dominance.
Differences in population growth response to warming were responsible for an observed shift to an alternative community state with contrasting forms of ecosystem functioning. Self-reinforcing feedback mechanisms – which often protect plant communities from invasion – may therefore be sensitive to climate warming, particularly in arctic regions that are dominated by cold-adapted plant populations.
2. Changes from high to low herbivore density shortly preceded changes to low fire levels and a shift to warmer summers. These transitions occurred during a period of increasing nitrogen (N) availability. Shortly thereafter, there was a shift in landscape dominance from grasses to oaks and then a change to decreasing N availability.
3. Model predictions of tree–grass interaction outcomes varied over time with respect to all environmental changes. During the time of high disturbances and cool summers, grasses were predicted to out-compete oaks. After climate warming and the loss of regular disturbances, the predicted outcome was stable coexistence. However, changes in the N cycle corresponded with different predicted outcomes: unstable competition under increasing N availability and facilitation of oaks by grasses when N availability was declining.
4. Akaike Information Criterion weights indicate that climate warming and fewer fires were consistent with the best-fitting model of oak–grass interactions for the entire time series (i.e. competitive exclusion to stable coexistence). However, reconciling the conflicting model predictions with the observed population dynamics suggests that a temporary period of unstable competition preceded the predicted shift to stable coexistence. This dynamic behaviour is consistent with known patterns of shifts between alternative stable states.
5. Synthesis. We show that abrupt changes in environmental conditions over time lead to similarly abrupt changes in tree–grass interaction outcomes, which were shown to vary in contrasting directions with respect to resource versus non-resource variables. The approach described here allows plant ecologists to test hypotheses of plant–plant interactions over successional time scales for long-lived species and thus can lead to new knowledge about the structural role of these interactions in community dynamics.
changes in plant community composition due to differences in species-specific nutrient requirements. What remains
unknown, however, is the extent to which climate change will alter the relationship between plant communities and the
nitrogen cycle. During intervals of climate change, do changes in nitrogen cycling lead to vegetation change or do changes
in community composition alter the nitrogen dynamics? We used long-term ecological data to determine the role of
nitrogen availability in changes of forest species composition under a rapidly changing climate during the early Holocene
(16k to 8k cal. yrs. BP). A statistical computational analysis of ecological data spanning 8,000 years showed that secondary
succession from a coniferous to deciduous forest occurred independently of changes in the nitrogen cycle. As oak replaced
pine under a warming climate, nitrogen cycling rates increased. Interestingly, the mechanism by which the species
interacted with nitrogen remained stable across this threshold change in climate and in the dominant tree species. This
suggests that changes in tree population density over successional time scales are not driven by nitrogen availability. Thus, current models of forest succession that incorporate the effects of available nitrogen may be over-estimating tree
population responses to changes in this resource, which may result in biased predictions of future forest dynamics under
climate warming.
Recent and Most-Cited Papers by Elizabeth Jeffers
Here, we applied mechanistic models of plant–environment interactions to palaeoecological time series data to determine the most likely functional relationships of Empetrum (crowberry) and Betula (birch) with millennial-scale changes in climate, fire activity, nitrogen cycling and herbivore density in an Irish heathland.
Herbivory and fire activity preferentially removed Betula from the landscape. Empetrum had a positive feedback on fire activity, but the effect of Betula was slightly negative. Nitrogen cycling was not strongly controlled by plant population dynamics. Betula had a greater temperature-dependent population growth rate than Empetrum; thus climate warming promoted Betula expansion into the heathland and this led to reduced fire activity and greater herbivory, which further reinforced Betula dominance.
Differences in population growth response to warming were responsible for an observed shift to an alternative community state with contrasting forms of ecosystem functioning. Self-reinforcing feedback mechanisms – which often protect plant communities from invasion – may therefore be sensitive to climate warming, particularly in arctic regions that are dominated by cold-adapted plant populations.
2. Changes from high to low herbivore density shortly preceded changes to low fire levels and a shift to warmer summers. These transitions occurred during a period of increasing nitrogen (N) availability. Shortly thereafter, there was a shift in landscape dominance from grasses to oaks and then a change to decreasing N availability.
3. Model predictions of tree–grass interaction outcomes varied over time with respect to all environmental changes. During the time of high disturbances and cool summers, grasses were predicted to out-compete oaks. After climate warming and the loss of regular disturbances, the predicted outcome was stable coexistence. However, changes in the N cycle corresponded with different predicted outcomes: unstable competition under increasing N availability and facilitation of oaks by grasses when N availability was declining.
4. Akaike Information Criterion weights indicate that climate warming and fewer fires were consistent with the best-fitting model of oak–grass interactions for the entire time series (i.e. competitive exclusion to stable coexistence). However, reconciling the conflicting model predictions with the observed population dynamics suggests that a temporary period of unstable competition preceded the predicted shift to stable coexistence. This dynamic behaviour is consistent with known patterns of shifts between alternative stable states.
5. Synthesis. We show that abrupt changes in environmental conditions over time lead to similarly abrupt changes in tree–grass interaction outcomes, which were shown to vary in contrasting directions with respect to resource versus non-resource variables. The approach described here allows plant ecologists to test hypotheses of plant–plant interactions over successional time scales for long-lived species and thus can lead to new knowledge about the structural role of these interactions in community dynamics.
changes in plant community composition due to differences in species-specific nutrient requirements. What remains
unknown, however, is the extent to which climate change will alter the relationship between plant communities and the
nitrogen cycle. During intervals of climate change, do changes in nitrogen cycling lead to vegetation change or do changes
in community composition alter the nitrogen dynamics? We used long-term ecological data to determine the role of
nitrogen availability in changes of forest species composition under a rapidly changing climate during the early Holocene
(16k to 8k cal. yrs. BP). A statistical computational analysis of ecological data spanning 8,000 years showed that secondary
succession from a coniferous to deciduous forest occurred independently of changes in the nitrogen cycle. As oak replaced
pine under a warming climate, nitrogen cycling rates increased. Interestingly, the mechanism by which the species
interacted with nitrogen remained stable across this threshold change in climate and in the dominant tree species. This
suggests that changes in tree population density over successional time scales are not driven by nitrogen availability. Thus, current models of forest succession that incorporate the effects of available nitrogen may be over-estimating tree
population responses to changes in this resource, which may result in biased predictions of future forest dynamics under
climate warming.