Simon Mortimer | University of Reading (original) (raw)
Papers by Simon Mortimer
Aspects of applied biology, 2012
Grassland restoration is the dominant activity funded by agri-environment schemes (AES). However,... more Grassland restoration is the dominant activity funded by agri-environment schemes (AES). However, the re-instatement of biodiversity and ecosystem services is limited by a number of severe abiotic and biotic constraints resulting from previous agricultural management. These appear to be less severe on ex-arable sites compared with permanent grassland. We report findings of a large research programme into practical solutions to these constraints. The key abiotic constraint was high residual soil fertility, particularly phosphorus. This can most easily be addressed by targeting of sites of low nutrient status. The chief biotic constraints were lack of propagules of desirable species and suitable sites for their establishment. Addition of seed mixtures or green hay to gaps created by either mechanical disturbance or herbicide was the most effective means of overcoming these factors. Finally, manipulation of biotic interactions, including hemiparasitic plants to reduce competition from grasses and control of mollusc herbivory of sown species, significantly improved the effectiveness of these techniques.
The Royal Society of Chemistry eBooks, Jul 1, 2010
RSC Publishing Logo. ...
Environmental Microbiology, Oct 1, 2009
SummaryMicrobial communities respond to a variety of environmental factors related to resources (... more SummaryMicrobial communities respond to a variety of environmental factors related to resources (e.g. plant and soil organic matter), habitat (e.g. soil characteristics) and predation (e.g. nematodes, protozoa and viruses). However, the relative contribution of these factors on microbial community composition is poorly understood. Here, we sampled soils from 30 chalk grassland fields located in three different chalk hill ridges of Southern England, using a spatially explicit sampling scheme. We assessed microbial communities via phospholipid fatty acid (PLFA) analyses and PCR‐denaturing gradient gel electrophoresis (DGGE) and measured soil characteristics, as well as nematode and plant community composition. The relative influences of space, soil, vegetation and nematodes on soil microorganisms were contrasted using variation partitioning and path analysis. Results indicate that soil characteristics and plant community composition, representing habitat and resources, shape soil microbial community composition, whereas the influence of nematodes, a potential predation factor, appears to be relatively small. Spatial variation in microbial community structure was detected at broad (between fields) and fine (within fields) scales, suggesting that microbial communities exhibit biogeographic patterns at different scales. Although our analysis included several relevant explanatory data sets, a large part of the variation in microbial communities remained unexplained (up to 92% in some analyses). However, in several analyses, significant parts of the variation in microbial community structure could be explained. The results of this study contribute to our understanding of the relative importance of different environmental and spatial factors in driving the composition of soil‐borne microbial communities.
ABSTRACT succession of species in ecosystems is one of the most important yet controversial topic... more ABSTRACT succession of species in ecosystems is one of the most important yet controversial topics in ecology. The degree to which succession is deterministic, convergent, and predictable has been vigorously debated for nearly a century. In this study, we provide the first experimental evidence, to our knowledge, that succession can simultaneously be predictable and unpredictable. We manipulated initial plant species composition on abandoned arable land in the Netherlands and subsequently allowed natural colonization over nine years. We show that initial compositional variation causes plant communities to follow divergent pathways of succession in species composition. Such divergence makes succession appear strongly unpredictable. However, these same communities exhibit striking patterns of convergence in the composition of trait-based groups of plant species, indicating highly deterministic assembly rules. This contrast between species divergence and trait convergence is attributable to priority effects involving inhibition or facilitation rather than to statistical inevitability, dispersal limitation, or community neutrality. These results have profound implications for restoration of biodiversity: restoring specific species compositions may require detailed knowledge of how initial community states determine the direction of ecosystem assembly, even when communities converge predictably in species traits
Basic and Applied Ecology, Oct 1, 2008
Root herbivores can have a positive or negative effect on the abundance and/or performance of fol... more Root herbivores can have a positive or negative effect on the abundance and/or performance of foliar phytophages. In addition, abiotic factors such as drought can either strengthen or weaken this effect, depending on the system under investigation. One explanation for these varying responses lies in differences in the physiological response of host plants to drought and root herbivores. Here, the impacts of root phytophages on a leaf-mining species feeding on annual and perennial plant species (four Sonchus species) were compared. The responses of plants and leaf-miners to drought and root herbivore treatments were not related to whether the host plant was an annual or perennial. However, where root feeders did affect foliar phytophage performance, this occurred only under a drought treatment, demonstrating the potential for climate change to alter the outcome of plant-mediated interactions.
Ecology Letters, Aug 7, 2012
Ecological Indicators, Jun 1, 2019
The NERC and CEH trademarks and logos ('the Trademarks') are registered trademarks of NERC in the... more The NERC and CEH trademarks and logos ('the Trademarks') are registered trademarks of NERC in the UK and other countries, and may not be used without the prior written consent of the Trademark owner.
Ecology Letters, Dec 1, 2005
Despite decades of research, it remains controversial whether ecological communities converge tow... more Despite decades of research, it remains controversial whether ecological communities converge towards a common structure determined by environmental conditions irrespective of assembly history. Here, we show experimentally that the answer depends on the level of community organization considered. In a 9-year grassland experiment, we manipulated initial plant composition on abandoned arable land and subsequently allowed natural colonization. Initial compositional variation caused plant communities to remain divergent in species identities, even though these same communities converged strongly in species traits. This contrast between species divergence and trait convergence could not be explained by dispersal limitation or community neutrality alone. Our results show that the simultaneous operation of trait-based assembly rules and species-level priority effects drives community assembly, making it both deterministic and historically contingent, but at different levels of community organization.
Soil Biology & Biochemistry, Feb 1, 2012
Ecosystems consist of aboveground and belowground subsystems and the structure of their communiti... more Ecosystems consist of aboveground and belowground subsystems and the structure of their communities is known to change with distance. However, most of this knowledge originates from visible, aboveground components, whereas relatively little is known about how soil community structure varies with distance and if this variability depends on the group of organisms considered. In the present study, we analyzed 30 grasslands from three neighboring chalk hill ridges in southern UK to determine the effect of geographic distance (1e198 km) on the similarity of bacterial communities and of nematode communities in the soil. We found that for both groups, community similarity decayed with distance and that this spatial pattern was not related to changes either in plant community composition or soil chemistry. Site history may have contributed to the observed pattern in the case of nematodes, since the distance effect depended on the presence of different nematode taxa at one of the hill ridges. On the other hand, site-related differences in bacterial community composition alone could not explain the spatial turnover, suggesting that other factors, such as biotic gradients and local dispersal processes that we did not include in our analysis, may be involved in the observed pattern. We conclude that, independently of the variety of causal factors that may be involved, the decay in similarity with geographic distance is a characteristic feature of both communities of soil bacteria and nematodes.
defined ecosystem services, that will be based on a much improved understanding of economic oppor... more defined ecosystem services, that will be based on a much improved understanding of economic opportunities and consequences.
British journal of entomology and natural history, 2009
Global Sustainability, 2018
Non-technical summaryOur current global food system – from food production to consumption, includ... more Non-technical summaryOur current global food system – from food production to consumption, including manufacture, packaging, transport, retail and associated businesses – is responsible for extensive negative social and environmental impacts which threaten the long-term well-being of society. This has led to increasing calls from science–policy organizations for major reform and transformation of the global food system. However, our knowledge regarding food system transformations is fragmented and this is hindering the development of co-ordinated solutions. Here, we collate recent research across several academic disciplines and sectors in order to better understand the mechanisms that ‘lock-in’ food systems in unsustainable states.
Ecosystems, 2018
Soil organic matter (SOM) is declining in most agricultural ecosystems, impacting multiple ecosys... more Soil organic matter (SOM) is declining in most agricultural ecosystems, impacting multiple ecosystem services including erosion and flood prevention, climate and greenhouse gas regulation as well as other services that underpin crop production, such as nutrient cycling and pest control. Ecological intensification aims to enhance crop productivity by including regulating and supporting ecosystem service management into agricultural practices. We investigate the potential for increased SOM to support the ecological intensification of arable systems by reducing the need for
Restoration schemes aimed at enhancing plant species diversity of improved agricultural grassland... more Restoration schemes aimed at enhancing plant species diversity of improved agricultural grassland have been a key feature of agri-environmental policy since the mid 1980s. Allied to this has been much research aimed at providing policy makers with guidelines on how best to manage grassland to restore botanical diversity. This research includes long-term studies of the consequences for grassland diversity of management techniques such as different hay cut dates, fertiliser additions, seed introductions and grazing regimes. Studies have also explored the role of introductions of Rhinanthus minor into species-poor swards to debilitate competitive grasses. While these studies have been successful in identifying some management features that control plant species diversity in agricultural grassland, they have taken a largely aboveground perspective on plant community dynamics.
Bulletin of the British …, 2003
Biological Conservation, 2012
The NERC and CEH trademarks and logos ('the Trademarks') are registered trademarks of NERC in the... more The NERC and CEH trademarks and logos ('the Trademarks') are registered trademarks of NERC in the UK and other countries, and may not be used without the prior written consent of the Trademark owner.
… Papers (PR)UCC, …, 2007
Wet habitats are considered a potentially important component of the farmed landscape for biodive... more Wet habitats are considered a potentially important component of the farmed landscape for biodiversity, including provision of a range of resources for declining farmland bird species. The Wetting Up Farmland for Birds and other Biodiversity (WUFFB) project in England is ...
Aspects of applied biology, 2011
ABSTRACT
Aspects of applied biology, 2012
Grassland restoration is the dominant activity funded by agri-environment schemes (AES). However,... more Grassland restoration is the dominant activity funded by agri-environment schemes (AES). However, the re-instatement of biodiversity and ecosystem services is limited by a number of severe abiotic and biotic constraints resulting from previous agricultural management. These appear to be less severe on ex-arable sites compared with permanent grassland. We report findings of a large research programme into practical solutions to these constraints. The key abiotic constraint was high residual soil fertility, particularly phosphorus. This can most easily be addressed by targeting of sites of low nutrient status. The chief biotic constraints were lack of propagules of desirable species and suitable sites for their establishment. Addition of seed mixtures or green hay to gaps created by either mechanical disturbance or herbicide was the most effective means of overcoming these factors. Finally, manipulation of biotic interactions, including hemiparasitic plants to reduce competition from grasses and control of mollusc herbivory of sown species, significantly improved the effectiveness of these techniques.
The Royal Society of Chemistry eBooks, Jul 1, 2010
RSC Publishing Logo. ...
Environmental Microbiology, Oct 1, 2009
SummaryMicrobial communities respond to a variety of environmental factors related to resources (... more SummaryMicrobial communities respond to a variety of environmental factors related to resources (e.g. plant and soil organic matter), habitat (e.g. soil characteristics) and predation (e.g. nematodes, protozoa and viruses). However, the relative contribution of these factors on microbial community composition is poorly understood. Here, we sampled soils from 30 chalk grassland fields located in three different chalk hill ridges of Southern England, using a spatially explicit sampling scheme. We assessed microbial communities via phospholipid fatty acid (PLFA) analyses and PCR‐denaturing gradient gel electrophoresis (DGGE) and measured soil characteristics, as well as nematode and plant community composition. The relative influences of space, soil, vegetation and nematodes on soil microorganisms were contrasted using variation partitioning and path analysis. Results indicate that soil characteristics and plant community composition, representing habitat and resources, shape soil microbial community composition, whereas the influence of nematodes, a potential predation factor, appears to be relatively small. Spatial variation in microbial community structure was detected at broad (between fields) and fine (within fields) scales, suggesting that microbial communities exhibit biogeographic patterns at different scales. Although our analysis included several relevant explanatory data sets, a large part of the variation in microbial communities remained unexplained (up to 92% in some analyses). However, in several analyses, significant parts of the variation in microbial community structure could be explained. The results of this study contribute to our understanding of the relative importance of different environmental and spatial factors in driving the composition of soil‐borne microbial communities.
ABSTRACT succession of species in ecosystems is one of the most important yet controversial topic... more ABSTRACT succession of species in ecosystems is one of the most important yet controversial topics in ecology. The degree to which succession is deterministic, convergent, and predictable has been vigorously debated for nearly a century. In this study, we provide the first experimental evidence, to our knowledge, that succession can simultaneously be predictable and unpredictable. We manipulated initial plant species composition on abandoned arable land in the Netherlands and subsequently allowed natural colonization over nine years. We show that initial compositional variation causes plant communities to follow divergent pathways of succession in species composition. Such divergence makes succession appear strongly unpredictable. However, these same communities exhibit striking patterns of convergence in the composition of trait-based groups of plant species, indicating highly deterministic assembly rules. This contrast between species divergence and trait convergence is attributable to priority effects involving inhibition or facilitation rather than to statistical inevitability, dispersal limitation, or community neutrality. These results have profound implications for restoration of biodiversity: restoring specific species compositions may require detailed knowledge of how initial community states determine the direction of ecosystem assembly, even when communities converge predictably in species traits
Basic and Applied Ecology, Oct 1, 2008
Root herbivores can have a positive or negative effect on the abundance and/or performance of fol... more Root herbivores can have a positive or negative effect on the abundance and/or performance of foliar phytophages. In addition, abiotic factors such as drought can either strengthen or weaken this effect, depending on the system under investigation. One explanation for these varying responses lies in differences in the physiological response of host plants to drought and root herbivores. Here, the impacts of root phytophages on a leaf-mining species feeding on annual and perennial plant species (four Sonchus species) were compared. The responses of plants and leaf-miners to drought and root herbivore treatments were not related to whether the host plant was an annual or perennial. However, where root feeders did affect foliar phytophage performance, this occurred only under a drought treatment, demonstrating the potential for climate change to alter the outcome of plant-mediated interactions.
Ecology Letters, Aug 7, 2012
Ecological Indicators, Jun 1, 2019
The NERC and CEH trademarks and logos ('the Trademarks') are registered trademarks of NERC in the... more The NERC and CEH trademarks and logos ('the Trademarks') are registered trademarks of NERC in the UK and other countries, and may not be used without the prior written consent of the Trademark owner.
Ecology Letters, Dec 1, 2005
Despite decades of research, it remains controversial whether ecological communities converge tow... more Despite decades of research, it remains controversial whether ecological communities converge towards a common structure determined by environmental conditions irrespective of assembly history. Here, we show experimentally that the answer depends on the level of community organization considered. In a 9-year grassland experiment, we manipulated initial plant composition on abandoned arable land and subsequently allowed natural colonization. Initial compositional variation caused plant communities to remain divergent in species identities, even though these same communities converged strongly in species traits. This contrast between species divergence and trait convergence could not be explained by dispersal limitation or community neutrality alone. Our results show that the simultaneous operation of trait-based assembly rules and species-level priority effects drives community assembly, making it both deterministic and historically contingent, but at different levels of community organization.
Soil Biology & Biochemistry, Feb 1, 2012
Ecosystems consist of aboveground and belowground subsystems and the structure of their communiti... more Ecosystems consist of aboveground and belowground subsystems and the structure of their communities is known to change with distance. However, most of this knowledge originates from visible, aboveground components, whereas relatively little is known about how soil community structure varies with distance and if this variability depends on the group of organisms considered. In the present study, we analyzed 30 grasslands from three neighboring chalk hill ridges in southern UK to determine the effect of geographic distance (1e198 km) on the similarity of bacterial communities and of nematode communities in the soil. We found that for both groups, community similarity decayed with distance and that this spatial pattern was not related to changes either in plant community composition or soil chemistry. Site history may have contributed to the observed pattern in the case of nematodes, since the distance effect depended on the presence of different nematode taxa at one of the hill ridges. On the other hand, site-related differences in bacterial community composition alone could not explain the spatial turnover, suggesting that other factors, such as biotic gradients and local dispersal processes that we did not include in our analysis, may be involved in the observed pattern. We conclude that, independently of the variety of causal factors that may be involved, the decay in similarity with geographic distance is a characteristic feature of both communities of soil bacteria and nematodes.
defined ecosystem services, that will be based on a much improved understanding of economic oppor... more defined ecosystem services, that will be based on a much improved understanding of economic opportunities and consequences.
British journal of entomology and natural history, 2009
Global Sustainability, 2018
Non-technical summaryOur current global food system – from food production to consumption, includ... more Non-technical summaryOur current global food system – from food production to consumption, including manufacture, packaging, transport, retail and associated businesses – is responsible for extensive negative social and environmental impacts which threaten the long-term well-being of society. This has led to increasing calls from science–policy organizations for major reform and transformation of the global food system. However, our knowledge regarding food system transformations is fragmented and this is hindering the development of co-ordinated solutions. Here, we collate recent research across several academic disciplines and sectors in order to better understand the mechanisms that ‘lock-in’ food systems in unsustainable states.
Ecosystems, 2018
Soil organic matter (SOM) is declining in most agricultural ecosystems, impacting multiple ecosys... more Soil organic matter (SOM) is declining in most agricultural ecosystems, impacting multiple ecosystem services including erosion and flood prevention, climate and greenhouse gas regulation as well as other services that underpin crop production, such as nutrient cycling and pest control. Ecological intensification aims to enhance crop productivity by including regulating and supporting ecosystem service management into agricultural practices. We investigate the potential for increased SOM to support the ecological intensification of arable systems by reducing the need for
Restoration schemes aimed at enhancing plant species diversity of improved agricultural grassland... more Restoration schemes aimed at enhancing plant species diversity of improved agricultural grassland have been a key feature of agri-environmental policy since the mid 1980s. Allied to this has been much research aimed at providing policy makers with guidelines on how best to manage grassland to restore botanical diversity. This research includes long-term studies of the consequences for grassland diversity of management techniques such as different hay cut dates, fertiliser additions, seed introductions and grazing regimes. Studies have also explored the role of introductions of Rhinanthus minor into species-poor swards to debilitate competitive grasses. While these studies have been successful in identifying some management features that control plant species diversity in agricultural grassland, they have taken a largely aboveground perspective on plant community dynamics.
Bulletin of the British …, 2003
Biological Conservation, 2012
The NERC and CEH trademarks and logos ('the Trademarks') are registered trademarks of NERC in the... more The NERC and CEH trademarks and logos ('the Trademarks') are registered trademarks of NERC in the UK and other countries, and may not be used without the prior written consent of the Trademark owner.
… Papers (PR)UCC, …, 2007
Wet habitats are considered a potentially important component of the farmed landscape for biodive... more Wet habitats are considered a potentially important component of the farmed landscape for biodiversity, including provision of a range of resources for declining farmland bird species. The Wetting Up Farmland for Birds and other Biodiversity (WUFFB) project in England is ...
Aspects of applied biology, 2011
ABSTRACT