The Experts below are selected from a list of 8442 Experts worldwide ranked by ideXlab platform
Clive G. Jones - One of the best experts on this subject based on the ideXlab platform.
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Ecosystem Engineers and geomorphological signatures in landscapes
Geomorphology, 2011Co-Authors: Clive G. JonesAbstract:Abstract Biogeomorphologists study the roles of biota in landscape formation and decay. Ecologists interested in Ecosystem engineering study environmental change caused by biota and the consequences for the engineer, other organisms, and ecological processes. The interface is geomorphological change, an interface both are aware of but study somewhat independently and differently. Interaction and integration among the two fields is the goal of this special issue. Here I take an ecological perspective of geomorphological change caused by Ecosystem Engineers in patches within landscapes that I hope can help facilitate this goal. I ask the following general questions: When will an Ecosystem engineering species create a geomorphological signature in a landscape? What, in qualitative terms, is such a signature? How can the signature be estimated and how long will it last? What engineer attributes and ecological factors will determine signature change? What creates complications? How do the answers inform whether or not life leaves a geomorphological signature? To attempt answers, I develop a provisional, general theory of Ecosystem engineering signatures that draws on and integrates a geomorphological foundation of balance between formation and decay; landscape patch dynamics; a general framework for Ecosystem engineering; and empirical studies. I treat a landscape engineering signature as the balance of rates of formation (F) and rates of decay (D) across patches whose ratio value (F/D) can be transformed (> 1), intermediate (1) or untransformed (
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physical Ecosystem Engineers and the functioning of estuaries and coasts
Reference Module in Earth Systems and Environmental Sciences#R##N#Treatise on Estuarine and Coastal Science, 2011Co-Authors: Jorge L Gutierrez, Clive G. Jones, James E Byers, John G Lambrinos, K K Arkema, K Berkenbusch, John A Commito, Carlos M Duarte, S D Hacker, Iris E HendriksAbstract:A great diversity of organisms modify the physical structure of estuarine and coastal environments. These physical Ecosystem Engineers – particularly, dune and marsh plants, mangroves, seagrasses, kelps, reef-forming corals and bivalves, burrowing crustaceans, and infauna – often have substantive functional impacts over large areas and across distinct geographic regions. Here, we use a general framework for physical Ecosystem engineering to illustrate how these organisms can exert control on sedimentary processes, coastal protection, and habitat availability to other organisms. We then discuss the management implications of coastal and estuarine engineering, concluding with a brief prospectus on research and management challenges.
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assessing impacts of Ecosystem Engineers on community organization a general approach illustrated by effects of a high andean cushion plant
Oikos, 2006Co-Authors: Ernesto I Badano, Clive G. Jones, Lohengrin A Cavieres, Justin P. WrightAbstract:Badano, E. I., Jones, C. G., Cavieres, L. A. and Wright, J. P. 2006. Assessing impacts of Ecosystem Engineers on community organization: a general approach illustrated by effects of a high-Andean cushion plant. � Oikos 115: 369 � 385. Comparative and integrative tools are of fundamental value in ecology for understanding outcomes of biological processes, and making generalizations and predictions. Although Ecosystem engineering has been shown to play a fundamental role in community organization, there are no standardized methods to measure such effects. We present a framework and methodology for assessing the impact of physical Ecosystem Engineers on three general features of community organization: (1) species richness and composition, (2) stability of richness over time, and (3) dominance patterns of species assemblages. We then apply the framework and methodology to assess the effects of the cushion plant Azorella monantha on high-Andean plant communities on two mountaintops. Substrate temperatures, soil moisture and the availability of mineral nutrient resources were compared between A. monantha and surrounding open areas to ascertain whether cushions altered abiotic environmental conditions, while community analysis assessed changes in species richness, composition and abundances at patch and landscape levels. Cushions thermally buffered temperature extremes and increased soil moisture, but had no detectable effect on soil mineral nutrients. Cushion habitat was not more species rich than surrounding areas, but cushions added new species into the community, altering species composition and markedly enhancing landscape-level richness. Cushions also showed potential for stabilizing species richness over time, and changed patterns of species dominance. Findings were consistent across mountaintops. We evaluate the general utility of the framework and call for its application in other systems as a means to generate comparative data sets for assessing the general effects of Ecosystem Engineers on community organization.
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using Ecosystem Engineers to restore ecological systems
Trends in Ecology and Evolution, 2006Co-Authors: James E Byers, Kim Cuddington, Alan Hastings, Clive G. Jones, Theresa Sinicrope Talley, John G Lambrinos, Jeffrey A Crooks, William G. WilsonAbstract:Ecosystem Engineers affect other organisms by creating, modifying, maintaining or destroying habitats. Despite widespread recognition of these often important effects, the Ecosystem engineering concept has yet to be widely used in ecological applications. Here, we present a conceptual framework that shows how consideration of Ecosystem Engineers can be used to assess the likelihood of restoration of a system to a desired state, the type of changes necessary for successful restoration and how restoration efforts can be most effectively partitioned between direct human intervention and natural Ecosystem Engineers.
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physical Ecosystem Engineers as agents of biogeochemical heterogeneity
BioScience, 2006Co-Authors: Jorge L Gutierrez, Clive G. JonesAbstract:Abstract Physical Ecosystem Engineers are organisms that physically modify the abiotic environment. They can affect biogeochemical processing by changing the availability of resources for microbes (e.g., carbon, nutrients) or by changing abiotic conditions affecting microbial process rates (e.g., soil moisture or temperature). Physical Ecosystem Engineers can therefore create biogeochemical heterogeneity in soils and sediments. They do so via general mechanisms influencing the flows of materials (i.e., modification of fluid dynamic properties, fluid pumping, and material transport) or the transfer of heat (i.e., modification of heat transfer properties, direct heat transfer, and convective forcing). The consequences of physical Ecosystem engineering for biogeochemical processes can be predicted by considering the resources or abiotic conditions that limit or promote a reaction, and the effect of physical Ecosystem engineering on these resources or abiotic conditions via the control they exert on material ...
Stefan Scheu - One of the best experts on this subject based on the ideXlab platform.
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exotic Ecosystem Engineers change the emergence of plants from the seed bank of a deciduous forest
Ecosystems, 2009Co-Authors: Nico Eisenhauer, Stefan Scheu, Daniela Straube, E A Johnson, D ParkinsonAbstract:The anthropogenic spread of exotic Ecosystem Engineers profoundly impacts native Ecosystems. Exotic earthworms were shown to alter plant community composition of the understory of deciduous forests previously devoid of earthworms. We investigated the effect of two exotic earthworm species (Lumbricus terrestris L. and Octolasion tyrtaeum Savigny) belonging to different ecological groups (anecic and endogeic) on the emergence of plants from the seed bank of a northern North American deciduous forest using the seedling emergence method. We hypothesized that (1) exotic earthworms change the seedling emergence from the plant seed bank, (2) L. terrestris increases the emergence of plant seedlings of the deeper soil layer but decreases that of the upper soil layer due to plant seed burial, and (3) O. tyrtaeum decreases plant seedling emergence due the damage of plant seeds. Indeed, exotic earthworms altered the emergence of plant seedlings from the seed bank and the functional composition of the established plant seedlings. Surprisingly, although L. terrestris only marginally affected seedling emergence, O. tyrtaeum changed the emergence of native plant species from the seed bank considerably. In particular, the number of emerging grass and herb seedlings were increased in the presence of O. tyrtaeum in both soil layers. Moreover, the impacts of earthworms depended on the identity of plant functional groups; herb species benefited, whereas legumes suffered from the presence of exotic earthworms. The results highlight the strong effect of invasive belowground Ecosystem Engineers on aboveground Ecosystem characteristics and suggest fundamental changes of Ecosystems by human-spread earthworm species.
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nonlinearity of effects of invasive Ecosystem Engineers on abiotic soil properties and soil biota
Oikos, 2009Co-Authors: Daniela Straube, Stefan Scheu, E A Johnson, D Parkinson, Nico EisenhauerAbstract:Invasions of non-indigenous species into natural communities are currently rated as one of the most important threats to biodiversity. Particularly exotic Ecosystem Engineers such as earthworms potentially have profound impacts on community assembly and functioning. We investigated the impact of invasion by the lumbricid earthworms into an aspen forest of the Canadian Rocky Mountains on soil organic matter, microorganisms and microarthropod communities. Building on the results of previous studies in this forest, we expected positive effects of Lumbricus terrestris middens and negative effects of Octolasion tyrtaeum on soil biota (increase and decrease in soil nutrient concentrations, microbial parameters and soil microarthropod density and diversity, respectively). Further, we expected that earthworm effects change with time. Combined results of previous and the present study suggest a wavelike colonization pattern for Dendrobaena octaedra and O. tyrtaeum and that indeed the impact of earthworms on soil biota changed with time, likely due to changes in earthworm density. Unexpectedly, L. terrestris middens neither affected soil abiotic nor soil biotic properties. By contrast and in contrast to our hypothesis, carbon and nitrogen concentration and C-to-N ratio in deeper soil layers increased in presence of O. tyrtaeum, thereby likely enhancing nutrient availability for soil microorganisms and microarthropods. Even though the density of this endogeic species was rather low, presence of O. tyrtaeum resulted in increased densities of a number of microarthropod taxa and increased microarthropod diversity. The results suggest that at low density, invasive Ecosystem Engineers, such as O. tyrtaeum, cause disturbances of intermediate strength thereby beneficially affecting soil microorganisms and most microarthropods. This contrasts earlier effects during the wavelike invasion of O. tyrtaeum into the aspen forest when densities of O. tyrtaeum were high resulting in generally detrimental effects on soil biota. The results emphasize the nonlinearity of earthworm effects on abiotic and biotic soil properties and call for further long-term investigations.
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Animal Ecosystem Engineers modulate the diversity-invasibility relationship.
PloS one, 2008Co-Authors: Nico Eisenhauer, Alexandru Milcu, Alexander C.w. Sabais, Stefan ScheuAbstract:Background Invasions of natural communities by non-indigenous species are currently rated as one of the most important global-scale threats to biodiversity. Biodiversity itself is known to reduce invasions and increase stability. Disturbances by Ecosystem Engineers affect the distribution, establishment, and abundance of species but this has been ignored in studies on diversity-invasibility relationships. Methodology/Principal Findings We determined natural plant invasion into 46 plots varying in the number of plant species (1, 4, and 16) and plant functional groups (1, 2, 3, and 4) for three years beginning two years after the establishment of the Jena Experiment. We sampled subplots where earthworms were artificially added and others where earthworm abundance was reduced. We also performed a seed-dummy experiment to investigate the role of earthworms as secondary seed dispersers along a plant diversity gradient. Horizontal dispersal and burial of seed dummies were significantly reduced in subplots where earthworms were reduced in abundance. Seed dispersal by earthworms decreased with increasing plant species richness and presence of grasses but increased in presence of small herbs. These results suggest that dense vegetation inhibits the surface activity of earthworms. Further, there was a positive relationship between the number of earthworms and the number and diversity of invasive plants. Hence, earthworms decreased the stability of grassland communities against plant invasion. Conclusions/Significance Invasibility decreased and stability increased with increasing plant diversity and, most remarkably, earthworms modulated the diversity-invasibility relationship. While the impacts of earthworms were unimportant in low diverse (low earthworm densities) and high diverse (high floral structural complexity) plant communities, earthworms decreased the stability of intermediate diverse plant communities against plant invasion. Overall, the results document that fundamental processes in plant communities like plant seed burial and invader establishment are modulated by soil fauna calling for closer cooperation between soil animal and plant ecologists.
Nico Eisenhauer - One of the best experts on this subject based on the ideXlab platform.
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exotic Ecosystem Engineers change the emergence of plants from the seed bank of a deciduous forest
Ecosystems, 2009Co-Authors: Nico Eisenhauer, Stefan Scheu, Daniela Straube, E A Johnson, D ParkinsonAbstract:The anthropogenic spread of exotic Ecosystem Engineers profoundly impacts native Ecosystems. Exotic earthworms were shown to alter plant community composition of the understory of deciduous forests previously devoid of earthworms. We investigated the effect of two exotic earthworm species (Lumbricus terrestris L. and Octolasion tyrtaeum Savigny) belonging to different ecological groups (anecic and endogeic) on the emergence of plants from the seed bank of a northern North American deciduous forest using the seedling emergence method. We hypothesized that (1) exotic earthworms change the seedling emergence from the plant seed bank, (2) L. terrestris increases the emergence of plant seedlings of the deeper soil layer but decreases that of the upper soil layer due to plant seed burial, and (3) O. tyrtaeum decreases plant seedling emergence due the damage of plant seeds. Indeed, exotic earthworms altered the emergence of plant seedlings from the seed bank and the functional composition of the established plant seedlings. Surprisingly, although L. terrestris only marginally affected seedling emergence, O. tyrtaeum changed the emergence of native plant species from the seed bank considerably. In particular, the number of emerging grass and herb seedlings were increased in the presence of O. tyrtaeum in both soil layers. Moreover, the impacts of earthworms depended on the identity of plant functional groups; herb species benefited, whereas legumes suffered from the presence of exotic earthworms. The results highlight the strong effect of invasive belowground Ecosystem Engineers on aboveground Ecosystem characteristics and suggest fundamental changes of Ecosystems by human-spread earthworm species.
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nonlinearity of effects of invasive Ecosystem Engineers on abiotic soil properties and soil biota
Oikos, 2009Co-Authors: Daniela Straube, Stefan Scheu, E A Johnson, D Parkinson, Nico EisenhauerAbstract:Invasions of non-indigenous species into natural communities are currently rated as one of the most important threats to biodiversity. Particularly exotic Ecosystem Engineers such as earthworms potentially have profound impacts on community assembly and functioning. We investigated the impact of invasion by the lumbricid earthworms into an aspen forest of the Canadian Rocky Mountains on soil organic matter, microorganisms and microarthropod communities. Building on the results of previous studies in this forest, we expected positive effects of Lumbricus terrestris middens and negative effects of Octolasion tyrtaeum on soil biota (increase and decrease in soil nutrient concentrations, microbial parameters and soil microarthropod density and diversity, respectively). Further, we expected that earthworm effects change with time. Combined results of previous and the present study suggest a wavelike colonization pattern for Dendrobaena octaedra and O. tyrtaeum and that indeed the impact of earthworms on soil biota changed with time, likely due to changes in earthworm density. Unexpectedly, L. terrestris middens neither affected soil abiotic nor soil biotic properties. By contrast and in contrast to our hypothesis, carbon and nitrogen concentration and C-to-N ratio in deeper soil layers increased in presence of O. tyrtaeum, thereby likely enhancing nutrient availability for soil microorganisms and microarthropods. Even though the density of this endogeic species was rather low, presence of O. tyrtaeum resulted in increased densities of a number of microarthropod taxa and increased microarthropod diversity. The results suggest that at low density, invasive Ecosystem Engineers, such as O. tyrtaeum, cause disturbances of intermediate strength thereby beneficially affecting soil microorganisms and most microarthropods. This contrasts earlier effects during the wavelike invasion of O. tyrtaeum into the aspen forest when densities of O. tyrtaeum were high resulting in generally detrimental effects on soil biota. The results emphasize the nonlinearity of earthworm effects on abiotic and biotic soil properties and call for further long-term investigations.
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Animal Ecosystem Engineers modulate the diversity-invasibility relationship.
PloS one, 2008Co-Authors: Nico Eisenhauer, Alexandru Milcu, Alexander C.w. Sabais, Stefan ScheuAbstract:Background Invasions of natural communities by non-indigenous species are currently rated as one of the most important global-scale threats to biodiversity. Biodiversity itself is known to reduce invasions and increase stability. Disturbances by Ecosystem Engineers affect the distribution, establishment, and abundance of species but this has been ignored in studies on diversity-invasibility relationships. Methodology/Principal Findings We determined natural plant invasion into 46 plots varying in the number of plant species (1, 4, and 16) and plant functional groups (1, 2, 3, and 4) for three years beginning two years after the establishment of the Jena Experiment. We sampled subplots where earthworms were artificially added and others where earthworm abundance was reduced. We also performed a seed-dummy experiment to investigate the role of earthworms as secondary seed dispersers along a plant diversity gradient. Horizontal dispersal and burial of seed dummies were significantly reduced in subplots where earthworms were reduced in abundance. Seed dispersal by earthworms decreased with increasing plant species richness and presence of grasses but increased in presence of small herbs. These results suggest that dense vegetation inhibits the surface activity of earthworms. Further, there was a positive relationship between the number of earthworms and the number and diversity of invasive plants. Hence, earthworms decreased the stability of grassland communities against plant invasion. Conclusions/Significance Invasibility decreased and stability increased with increasing plant diversity and, most remarkably, earthworms modulated the diversity-invasibility relationship. While the impacts of earthworms were unimportant in low diverse (low earthworm densities) and high diverse (high floral structural complexity) plant communities, earthworms decreased the stability of intermediate diverse plant communities against plant invasion. Overall, the results document that fundamental processes in plant communities like plant seed burial and invader establishment are modulated by soil fauna calling for closer cooperation between soil animal and plant ecologists.
Justin P. Wright - One of the best experts on this subject based on the ideXlab platform.
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Ecosystem Engineers maintain a rare species of butterfly and increase plant diversity
Oikos, 2010Co-Authors: Rebecca A Bartel, Nick M Haddad, Justin P. WrightAbstract:We evaluated whether Ecosystem Engineers can accomplish two conservation goals simultaneously: (1) indirectly maintain populations of an endangered animal through habitat modifi cation and (2) increase riparian plant diversity. We tested for eff ects of a prominent Ecosystem engineer, the beaver Castor canadensis, on populations of St. Francis’ satyr butterfl y Neonympha mitchellii francisci and plant species richness and composition. We performed our test by surveying riparian vegetation communities in all stages of beaver-infl uenced wetland succession. We found that beavers created wetland habitats that supported plant species not found elsewhere in riparian zones and increased plant species diversity across the landscape by creating a novel combination of patch types. Our results confi rmed what others have found about engineering eff ects on plant diversity, but these results further demonstrated a case where Ecosystem Engineers indirectly maintain populations of rare animals by modifying the composition and diversity of plant communities within wetlands. Our research demonstrates how an Ecosystem engineer can infl uence habitat availability and composition of plant communities important for an endangered insect, and maintain overall plant species diversity by increasing habitat heterogeneity.
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assessing impacts of Ecosystem Engineers on community organization a general approach illustrated by effects of a high andean cushion plant
Oikos, 2006Co-Authors: Ernesto I Badano, Clive G. Jones, Lohengrin A Cavieres, Justin P. WrightAbstract:Badano, E. I., Jones, C. G., Cavieres, L. A. and Wright, J. P. 2006. Assessing impacts of Ecosystem Engineers on community organization: a general approach illustrated by effects of a high-Andean cushion plant. � Oikos 115: 369 � 385. Comparative and integrative tools are of fundamental value in ecology for understanding outcomes of biological processes, and making generalizations and predictions. Although Ecosystem engineering has been shown to play a fundamental role in community organization, there are no standardized methods to measure such effects. We present a framework and methodology for assessing the impact of physical Ecosystem Engineers on three general features of community organization: (1) species richness and composition, (2) stability of richness over time, and (3) dominance patterns of species assemblages. We then apply the framework and methodology to assess the effects of the cushion plant Azorella monantha on high-Andean plant communities on two mountaintops. Substrate temperatures, soil moisture and the availability of mineral nutrient resources were compared between A. monantha and surrounding open areas to ascertain whether cushions altered abiotic environmental conditions, while community analysis assessed changes in species richness, composition and abundances at patch and landscape levels. Cushions thermally buffered temperature extremes and increased soil moisture, but had no detectable effect on soil mineral nutrients. Cushion habitat was not more species rich than surrounding areas, but cushions added new species into the community, altering species composition and markedly enhancing landscape-level richness. Cushions also showed potential for stabilizing species richness over time, and changed patterns of species dominance. Findings were consistent across mountaintops. We evaluate the general utility of the framework and call for its application in other systems as a means to generate comparative data sets for assessing the general effects of Ecosystem Engineers on community organization.
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The Concept of Organisms as Ecosystem Engineers Ten Years On: Progress, Limitations, and Challenges
BioScience, 2006Co-Authors: Justin P. Wright, Clive G. JonesAbstract:The modification of the physical environment by organisms is a critical interaction in most Ecosystems. The concept of Ecosystem engineering acknowledges this fact and allows ecologists to develop the conceptual tools for uncovering general patterns and building broadly applicable models. Although the concept has occasioned some controversy during its development, it is quickly gaining acceptance among ecologists. We outline the nature of some of these controversies and describe some of the major insights gained by viewing ecological systems through the lens of Ecosystem engineering. We close by discussing areas of research where we believe the concept of organisms as Ecosystem Engineers will be most likely to lead to significant insights into the structure and function of ecological systems.
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predicting effects of Ecosystem Engineers on patch scale species richness from primary productivity
Ecology, 2004Co-Authors: Justin P. Wright, Clive G. JonesAbstract:Ecosystem engineering—the physical modification of habitats by organisms—can create patches with altered species richness relative to adjacent, unmodified patches. The effect of Ecosystem engineering on patch-scale species richness is likely to be difficult to predict from the identity of the engineer, the resources altered as a result of engineering, or the identities of the affected species. Here we develop a simple conceptual model that predicts the effects of Ecosystem Engineers on species richness based on how the habitat modifications caused by Engineers affect primary productivity, assuming a hump-shaped relationship between productivity and species richness. We review data from 35 studies that contained 60 comparisons of species richness on patches that had been modified by Ecosystem Engineers vs. unmodified patches. We found no general patterns in whether species richness at the patch scale was increased or decreased by Ecosystem engineering. However, 14 of these studies also contained data on pr...
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Patch dynamics in a landscape modified by Ecosystem Engineers
Oikos, 2004Co-Authors: Justin P. Wright, William Gurney, Clive G. JonesAbstract:Ecosystem Engineers, organisms that modify the environment, have the potential to dramatically alter Ecosystem structure and function at large spatial scales. The degree to which Ecosystem engineering produces large-scale effects is, in part, dependent on the dynamics of the patches that Engineers create. Here we develop a set of models that links the population dynamics of Ecosystem Engineers to the dynamics of the patches that they create. We show that the relative abundance of different patch types in an engineered landscape is dependent upon the production of successful colonists from engineered patches and the rate at which critical resources are depleted by Engineers and then renewed. We also consider the effects of immigration from either outside the system or from Engineers that are present in non-engineered patches, and the effects of Engineers that can recolonize patches before they are fully recovered on the steady state distribution of different patch types. We use data collected on the population dynamics of a model engineer, the beaver, to estimate the per-patch production rate of new colonists, the decay rate of engineered patches, and the recovery rate of abandoned patches. We use these estimated parameters as a baseline to determine the effects of varying parameters on the distribution of different patch types. We suggest a number of hypotheses that derive from model predictions and that could serve as tests of the model.
Kathy Martin - One of the best experts on this subject based on the ideXlab platform.
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Habitat-Mediated Variation in the Importance of Ecosystem Engineers for Secondary Cavity Nesters in a Nest Web
2016Co-Authors: Hugo Robles, Kathy MartinAbstract:Through physical state changes in biotic or abiotic materials, Ecosystem Engineers modulate resource availability to other organisms and are major drivers of evolutionary and ecological dynamics. Understanding whether and how Ecosystem Engineers are interchangeable for resource users in different habitats is a largely neglected topic in Ecosystem engineering research that can improve our understanding of the structure of communities. We addressed this issue in a cavity-nest web (1999–2011). In aspen groves, the presence of mountain bluebird (Sialia currucoides) and tree swallow (Tachycineta bicolour) nests was positively related to the density of cavities supplied by northern flickers (Colaptes auratus), which provided the most abundant cavities (1.61 cavities/ha). Flickers in aspen groves provided numerous nesting cavities to bluebirds (66%) and swallows (46%), despite previous research showing that flicker cavities are avoided by swallows. In continuous mixed forests, however, the presence of nesting swallows was mainly related to cavity density of red-naped sapsuckers (Sphyrapicus nuchalis), which provided the most abundant cavities (0.52 cavities/ha), and to cavity density of hairy woodpeckers (Picoides villosus), which provided few (0.14 cavities/ha) but high-quality cavities. Overall, sapsuckers and hairy woodpeckers provided 86 % of nesting cavities to swallows in continuous forests. In contrast, the presence of nesting bluebirds in continuous forests was associated with the density of cavities supplied by all the Ecosystem Engineers. These results suggest that (i) habitat type may mediate the associations between Ecosystem Engineers and resource users, and (ii
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Habitat-mediated variation in the importance of Ecosystem Engineers for secondary cavity nesters in a nest web.
PloS one, 2014Co-Authors: Hugo Robles, Kathy MartinAbstract:Through physical state changes in biotic or abiotic materials, Ecosystem Engineers modulate resource availability to other organisms and are major drivers of evolutionary and ecological dynamics. Understanding whether and how Ecosystem Engineers are interchangeable for resource users in different habitats is a largely neglected topic in Ecosystem engineering research that can improve our understanding of the structure of communities. We addressed this issue in a cavity-nest web (1999–2011). In aspen groves, the presence of mountain bluebird (Sialia currucoides) and tree swallow (Tachycineta bicolour) nests was positively related to the density of cavities supplied by northern flickers (Colaptes auratus), which provided the most abundant cavities (1.61 cavities/ha). Flickers in aspen groves provided numerous nesting cavities to bluebirds (66%) and swallows (46%), despite previous research showing that flicker cavities are avoided by swallows. In continuous mixed forests, however, the presence of nesting swallows was mainly related to cavity density of red-naped sapsuckers (Sphyrapicus nuchalis), which provided the most abundant cavities (0.52 cavities/ha), and to cavity density of hairy woodpeckers (Picoides villosus), which provided few (0.14 cavities/ha) but high-quality cavities. Overall, sapsuckers and hairy woodpeckers provided 86% of nesting cavities to swallows in continuous forests. In contrast, the presence of nesting bluebirds in continuous forests was associated with the density of cavities supplied by all the Ecosystem Engineers. These results suggest that (i) habitat type may mediate the associations between Ecosystem Engineers and resource users, and (ii) different Ecosystem Engineers may be interchangeable for resource users depending on the quantity and quality of resources that each engineer supplies in each habitat type. We, therefore, urge the incorporation of the variation in the quantity and quality of resources provided by Ecosystem Engineers across habitats into models that assess community dynamics to improve our understanding of the importance of Ecosystem Engineers in shaping ecological communities.
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resource quantity and quality determine the inter specific associations between Ecosystem Engineers and resource users in a cavity nest web
PLOS ONE, 2013Co-Authors: Hugo Robles, Kathy MartinAbstract:While Ecosystem engineering is a widespread structural force of ecological communities, the mechanisms underlying the inter-specific associations between Ecosystem Engineers and resource users are poorly understood. A proper knowledge of these mechanisms is, however, essential to understand how communities are structured. Previous studies suggest that increasing the quantity of resources provided by Ecosystem Engineers enhances populations of resource users. In a long-term study (1995-2011), we show that the quality of the resources (i.e. tree cavities) provided by Ecosystem Engineers is also a key feature that explains the inter-specific associations in a tree cavity-nest web. Red-naped sapsuckers (Sphyrapicusnuchalis) provided the most abundant cavities (52% of cavities, 0.49 cavities/ha). These cavities were less likely to be used than other cavity types by mountain bluebirds (Sialiacurrucoides), but provided numerous nest-sites (41% of nesting cavities) to tree swallows (Tachycinetabicolour). Swallows experienced low reproductive outputs in northern flicker (Colaptesauratus) cavities compared to those in sapsucker cavities (1.1 vs. 2.1 fledglings/nest), but the highly abundant flickers (33% of cavities, 0.25 cavities/ha) provided numerous suitable nest-sites for bluebirds (58%). The relative shortage of cavities supplied by hairy woodpeckers (Picoidesvillosus) and fungal/insect decay (<10% of cavities each, <0.09 cavities/ha) provided fewer breeding opportunities (<15% of nests), but represented high quality nest-sites for both bluebirds and swallows. Because both the quantity and quality of resources supplied by different Ecosystem Engineers may explain the amount of resources used by each resource user, conservation strategies may require different management actions to be implemented for the key Ecosystem engineer of each resource user. We, therefore, urge the incorporation of both resource quantity and quality into models that assess community dynamics to improve conservation actions and our understanding of ecological communities based on Ecosystem engineering.
