Science.gov

Sample records for affecting ecosystem function

  1. Determining place and process: functional traits of ectomycorrhizal fungi that affect both community structure and ecosystem function.

    PubMed

    Koide, Roger T; Fernandez, Christopher; Malcolm, Glenna

    2014-01-01

    There is a growing interest amongst community ecologists in functional traits. Response traits determine membership in communities. Effect traits influence ecosystem function. One goal of community ecology is to predict the effect of environmental change on ecosystem function. Environmental change can directly and indirectly affect ecosystem function. Indirect effects are mediated through shifts in community structure. It is difficult to predict how environmental change will affect ecosystem function via the indirect route when the change in effect trait distribution is not predictable from the change in response trait distribution. When response traits function as effect traits, however, it becomes possible to predict the indirect effect of environmental change on ecosystem function. Here we illustrate four examples in which key attributes of ectomycorrhizal fungi function as both response and effect traits. While plant ecologists have discussed response and effect traits in the context of community structuring and ecosystem function, this approach has not been applied to ectomycorrhizal fungi. This is unfortunate because of the large effects of ectomycorrhizal fungi on ecosystem function. We hope to stimulate further research in this area in the hope of better predicting the ecosystem- and landscape-level effects of the fungi as influenced by changing environmental conditions.

  2. Small but powerful: top predator local extinction affects ecosystem structure and function in an intermittent stream.

    PubMed

    Rodríguez-Lozano, Pablo; Verkaik, Iraima; Rieradevall, Maria; Prat, Narcís

    2015-01-01

    Top predator loss is a major global problem, with a current trend in biodiversity loss towards high trophic levels that modifies most ecosystems worldwide. Most research in this area is focused on large-bodied predators, despite the high extinction risk of small-bodied freshwater fish that often act as apex consumers. Consequently, it remains unknown if intermittent streams are affected by the consequences of top-predators' extirpations. The aim of our research was to determine how this global problem affects intermittent streams and, in particular, if the loss of a small-bodied top predator (1) leads to a 'mesopredator release', affects primary consumers and changes whole community structures, and (2) triggers a cascade effect modifying the ecosystem function. To address these questions, we studied the top-down effects of a small endangered fish species, Barbus meridionalis (the Mediterranean barbel), conducting an enclosure/exclosure mesocosm experiment in an intermittent stream where B. meridionalis became locally extinct following a wildfire. We found that top predator absence led to 'mesopredator release', and also to 'prey release' despite intraguild predation, which contrasts with traditional food web theory. In addition, B. meridionalis extirpation changed whole macroinvertebrate community composition and increased total macroinvertebrate density. Regarding ecosystem function, periphyton primary production decreased in apex consumer absence. In this study, the apex consumer was functionally irreplaceable; its local extinction led to the loss of an important functional role that resulted in major changes to the ecosystem's structure and function. This study evidences that intermittent streams can be affected by the consequences of apex consumers' extinctions, and that the loss of small-bodied top predators can lead to large ecosystem changes. We recommend the reintroduction of small-bodied apex consumers to systems where they have been extirpated, to restore

  3. Small but powerful: top predator local extinction affects ecosystem structure and function in an intermittent stream.

    PubMed

    Rodríguez-Lozano, Pablo; Verkaik, Iraima; Rieradevall, Maria; Prat, Narcís

    2015-01-01

    Top predator loss is a major global problem, with a current trend in biodiversity loss towards high trophic levels that modifies most ecosystems worldwide. Most research in this area is focused on large-bodied predators, despite the high extinction risk of small-bodied freshwater fish that often act as apex consumers. Consequently, it remains unknown if intermittent streams are affected by the consequences of top-predators' extirpations. The aim of our research was to determine how this global problem affects intermittent streams and, in particular, if the loss of a small-bodied top predator (1) leads to a 'mesopredator release', affects primary consumers and changes whole community structures, and (2) triggers a cascade effect modifying the ecosystem function. To address these questions, we studied the top-down effects of a small endangered fish species, Barbus meridionalis (the Mediterranean barbel), conducting an enclosure/exclosure mesocosm experiment in an intermittent stream where B. meridionalis became locally extinct following a wildfire. We found that top predator absence led to 'mesopredator release', and also to 'prey release' despite intraguild predation, which contrasts with traditional food web theory. In addition, B. meridionalis extirpation changed whole macroinvertebrate community composition and increased total macroinvertebrate density. Regarding ecosystem function, periphyton primary production decreased in apex consumer absence. In this study, the apex consumer was functionally irreplaceable; its local extinction led to the loss of an important functional role that resulted in major changes to the ecosystem's structure and function. This study evidences that intermittent streams can be affected by the consequences of apex consumers' extinctions, and that the loss of small-bodied top predators can lead to large ecosystem changes. We recommend the reintroduction of small-bodied apex consumers to systems where they have been extirpated, to restore

  4. Plant Species and Functional Group Combinations Affect Green Roof Ecosystem Functions

    PubMed Central

    Lundholm, Jeremy; MacIvor, J. Scott; MacDougall, Zachary; Ranalli, Melissa

    2010-01-01

    Background Green roofs perform ecosystem services such as summer roof temperature reduction and stormwater capture that directly contribute to lower building energy use and potential economic savings. These services are in turn related to ecosystem functions performed by the vegetation layer such as radiation reflection and transpiration, but little work has examined the role of plant species composition and diversity in improving these functions. Methodology/Principal Findings We used a replicated modular extensive (shallow growing- medium) green roof system planted with monocultures or mixtures containing one, three or five life-forms, to quantify two ecosystem services: summer roof cooling and water capture. We also measured the related ecosystem properties/processes of albedo, evapotranspiration, and the mean and temporal variability of aboveground biomass over four months. Mixtures containing three or five life-form groups, simultaneously optimized several green roof ecosystem functions, outperforming monocultures and single life-form groups, but there was much variation in performance depending on which life-forms were present in the three life-form mixtures. Some mixtures outperformed the best monocultures for water capture, evapotranspiration, and an index combining both water capture and temperature reductions. Combinations of tall forbs, grasses and succulents simultaneously optimized a range of ecosystem performance measures, thus the main benefit of including all three groups was not to maximize any single process but to perform a variety of functions well. Conclusions/Significance Ecosystem services from green roofs can be improved by planting certain life-form groups in combination, directly contributing to climate change mitigation and adaptation strategies. The strong performance by certain mixtures of life-forms, especially tall forbs, grasses and succulents, warrants further investigation into niche complementarity or facilitation as mechanisms

  5. Small but Powerful: Top Predator Local Extinction Affects Ecosystem Structure and Function in an Intermittent Stream

    PubMed Central

    Rodríguez-Lozano, Pablo; Verkaik, Iraima; Rieradevall, Maria; Prat, Narcís

    2015-01-01

    Top predator loss is a major global problem, with a current trend in biodiversity loss towards high trophic levels that modifies most ecosystems worldwide. Most research in this area is focused on large-bodied predators, despite the high extinction risk of small-bodied freshwater fish that often act as apex consumers. Consequently, it remains unknown if intermittent streams are affected by the consequences of top-predators’ extirpations. The aim of our research was to determine how this global problem affects intermittent streams and, in particular, if the loss of a small-bodied top predator (1) leads to a ‘mesopredator release’, affects primary consumers and changes whole community structures, and (2) triggers a cascade effect modifying the ecosystem function. To address these questions, we studied the top-down effects of a small endangered fish species, Barbus meridionalis (the Mediterranean barbel), conducting an enclosure/exclosure mesocosm experiment in an intermittent stream where B. meridionalis became locally extinct following a wildfire. We found that top predator absence led to ‘mesopredator release’, and also to ‘prey release’ despite intraguild predation, which contrasts with traditional food web theory. In addition, B. meridionalis extirpation changed whole macroinvertebrate community composition and increased total macroinvertebrate density. Regarding ecosystem function, periphyton primary production decreased in apex consumer absence. In this study, the apex consumer was functionally irreplaceable; its local extinction led to the loss of an important functional role that resulted in major changes to the ecosystem’s structure and function. This study evidences that intermittent streams can be affected by the consequences of apex consumers’ extinctions, and that the loss of small-bodied top predators can lead to large ecosystem changes. We recommend the reintroduction of small-bodied apex consumers to systems where they have been

  6. Revealing how species loss affects ecosystem function: the trait-based Price Equation partition.

    PubMed

    Fox, Jeremy W; Harpole, W Stanley

    2008-01-01

    Species loss can alter ecosystem function. Recent work proposes a general theoretical framework, the "Price Equation partition," for understanding how species loss affects ecosystem functions that comprise the summed contributions of individual species (e.g., primary production). The Price Equation partition shows how the difference in function between a pre-species-loss site and a post-loss site can be partitioned into effects of random loss of species richness (species-richness effect; SRE), nonrandom loss of high- or low-functioning species (species-composition effect; SCE), and post-loss changes in the functional contributions of the remaining species (context-dependence effect; CDE). However, the Price Equation partition is silent on the underlying determinants of species' functional contributions. Here we extend the Price Equation partition by using multiple regression to describe how species' functional contributions depend on species' traits. This allows us to reexpress the SCE and CDE in terms of nonrandom loss of species with particular traits (trait-based SCE), and post-loss changes in species' traits and in the relationship between species' traits and species' functional contributions (trait-based CDE). We apply this new trait-based Price Equation partition to studies of species loss from grassland plant communities and protist microcosm food webs. In both studies, post-loss changes in the relationship between species' traits and their functional contributions alter ecosystem function more than nonrandom loss of species with particular traits. The protist microcosm data also illustrate how the trait-based Price Equation partition can be applied when species' functional contributions depend in part on the traits of other species. To do this, we define "synecological" traits that quantify how unique species are (e.g., in diet) compared to other species. Context dependence in the protist microcosm experiment arises in part because species loss alters the

  7. Realistic changes in seaweed biodiversity affect multiple ecosystem functions on a rocky shore.

    PubMed

    Bracken, Matthew E S; Williams, Susan L

    2013-09-01

    Given current threats to biodiversity, understanding the effects of diversity changes on the functions and services associated with intact ecosystems is of paramount importance. However, limited realism in most biodiversity studies makes it difficult to link the large and growing body of evidence for important functional consequences of biodiversity change to real-world losses of biodiversity. Here, we explored two methods of incorporating realism into biodiversity research: (1) the use of two-, five-, and eight-species assemblages that mimicked those that we observed in surveys of seaweed biodiversity patterns on a northern California (USA) rocky shore and the explicit comparison of those assemblages to random assemblages compiled from the same local species pool; and (2) the measurement of two fundamental ecosystem functions, nitrate uptake and photosynthesis, both of which contribute to growth of primary producers. Specifically, we measured nitrate uptake rates of seaweed assemblages as a function of initial nitrate concentrations and photosynthetic rates as a function of irradiance levels for both realistic and random assemblages of seaweeds. We only observed changes in ecosystem functioning along a richness gradient for realistic assemblages, and both maximum nitrate uptake rates (V(max)) and photosynthetic light use efficiency values (alpha(p) = P(max)/I(K)) were higher in realistic assemblages than in random assemblages. Furthermore, the parameter affected by changes in richness depended on the function being measured. Both V(max) and alpha(p) declined with increasing richness in nonrandom assemblages due to a combination of species identity effects (for V(max) and overyielding effects (for both V(max) and alpha(p)). In contrast, neither nitrate uptake efficiency values (alpha(N) = V(max)/K(s)), nor maximum photosynthetic rates (Pmax) changed along the gradient in seaweed species richness. Furthermore, overyielding was only evident in realistic assemblages

  8. Ecosystem structure, function, and composition in rangelands are negatively affected by livestock grazing.

    PubMed

    Eldridge, David J; Poore, Alistair G B; Ruiz-Colmenero, Marta; Letnic, Mike; Soliveres, Santiago

    2016-06-01

    Reports of positive or neutral effects of grazing on plant species richness have prompted calls for livestock grazing to be used as a tool for managing land for conservation. Grazing effects, however, are likely to vary among different response variables, types, and intensity of grazing, and across abiotic conditions. We aimed to examine how grazing affects ecosystem structure, function, and composition. We compiled a database of 7615 records reporting an effect of grazing by sheep and cattle on 278 biotic and abiotic response variables for published studies across Australia. Using these data, we derived three ecosystem measures based on structure, function, and composition, which were compared against six contrasts of grazing pressure, ranging from low to heavy, two different herbivores (sheep, cattle), and across three different climatic zones. Grazing reduced structure (by 35%), function (24%), and composition (10%). Structure and function (but not composition) declined more when grazed by sheep and cattle together than sheep alone. Grazing reduced plant biomass (40%), animal richness (15%), and plant and animal abundance, and plant and litter cover (25%), but had no effect on plant richness nor soil function. The negative effects of grazing on plant biomass, plant cover, and soil function were more pronounced in drier environments. Grazing effects on plant and animal richness and composition were constant, or even declined, with increasing aridity. Our study represents a comprehensive continental assessment of the implications of grazing for managing Australian rangelands. Grazing effects were largely negative, even at very low levels of grazing. Overall, our results suggest that livestock grazing in Australia is unlikely to produce positive outcomes for ecosystem structure, function, and composition or even as a blanket conservation tool unless reduction in specific response variables is an explicit management objective.

  9. Ecosystem structure, function, and composition in rangelands are negatively affected by livestock grazing.

    PubMed

    Eldridge, David J; Poore, Alistair G B; Ruiz-Colmenero, Marta; Letnic, Mike; Soliveres, Santiago

    2016-06-01

    Reports of positive or neutral effects of grazing on plant species richness have prompted calls for livestock grazing to be used as a tool for managing land for conservation. Grazing effects, however, are likely to vary among different response variables, types, and intensity of grazing, and across abiotic conditions. We aimed to examine how grazing affects ecosystem structure, function, and composition. We compiled a database of 7615 records reporting an effect of grazing by sheep and cattle on 278 biotic and abiotic response variables for published studies across Australia. Using these data, we derived three ecosystem measures based on structure, function, and composition, which were compared against six contrasts of grazing pressure, ranging from low to heavy, two different herbivores (sheep, cattle), and across three different climatic zones. Grazing reduced structure (by 35%), function (24%), and composition (10%). Structure and function (but not composition) declined more when grazed by sheep and cattle together than sheep alone. Grazing reduced plant biomass (40%), animal richness (15%), and plant and animal abundance, and plant and litter cover (25%), but had no effect on plant richness nor soil function. The negative effects of grazing on plant biomass, plant cover, and soil function were more pronounced in drier environments. Grazing effects on plant and animal richness and composition were constant, or even declined, with increasing aridity. Our study represents a comprehensive continental assessment of the implications of grazing for managing Australian rangelands. Grazing effects were largely negative, even at very low levels of grazing. Overall, our results suggest that livestock grazing in Australia is unlikely to produce positive outcomes for ecosystem structure, function, and composition or even as a blanket conservation tool unless reduction in specific response variables is an explicit management objective. PMID:27509764

  10. Urbanization affects stream ecosystem function by altering hydrology, chemistry, and biotic richness.

    PubMed

    Chadwick, Michael A; Dobberfuhl, Dean R; Benke, Arthur C; Huryn, Alexander D; Suberkropp, Keller; Thiele, John E

    2006-10-01

    Catchment urbanization can alter physical, chemical, and biological attributes of stream ecosystems. In particular, changes in land use may affect the dynamics of organic matter decomposition, a measure of ecosystem function. We examined leaf-litter decomposition in 18 tributaries of the St. Johns River, Florida, USA. Land use in all 18 catchments ranged from 0% to 93% urban which translated to 0% to 66% total impervious area (TIA). Using a litter-bag technique, we measured mass loss, fungal biomass, and macroinvertebrate biomass for two leaf species (red maple [Acer rubrum] and sweetgum [Liquidambar styraciflua]). Rates of litter mass loss, which ranged from 0.01 to 0.05 per day for red maple and 0.006 to 0.018 per day for sweetgum, increased with impervious catchment area to levels of approximately 30-40% TIA and then decreased as impervious catchment area exceeded 40% TIA. Fungal biomass was also highest in streams draining catchments with intermediate levels of TIA. Macroinvertebrate biomass ranged from 17 to 354 mg/bag for red maple and from 15 to 399 mg/bag for sweetgum. Snail biomass and snail and total invertebrate richness were strongly related to breakdown rates among streams regardless of leaf species. Land-use and physical, chemical, and biological variables were highly intercorrelated. Principal-components analysis was therefore used to reduce the variables into several orthogonal axes. Using stepwise regression, we found that flow regime, snail biomass, snail and total invertebrate richness, and metal and nutrient content (which varied in a nonlinear manner with impervious surface area) were likely factors affecting litter breakdown rates in these streams.

  11. Macrofauna assemblage composition and soil moisture interact to affect soil ecosystem functions

    NASA Astrophysics Data System (ADS)

    Collison, E. J.; Riutta, T.; Slade, E. M.

    2013-02-01

    Changing climatic conditions and habitat fragmentation are predicted to alter the soil moisture conditions of temperate forests. It is not well understood how the soil macrofauna community will respond to changes in soil moisture, and how changes to species diversity and community composition may affect ecosystem functions, such as litter decomposition and soil fluxes. Moreover, few studies have considered the interactions between the abiotic and biotic factors that regulate soil processes. Here we attempt to disentangle the interactive effects of two of the main factors that regulate soil processes at small scales - moisture and macrofauna assemblage composition. The response of assemblages of three common temperate soil invertebrates (Glomeris marginata Villers, Porcellio scaber Latreille and Philoscia muscorum Scopoli) to two contrasting soil moisture levels was examined in a series of laboratory mesocosm experiments. The contribution of the invertebrates to the leaf litter mass loss of two common temperate tree species of contrasting litter quality (easily decomposing Fraxinus excelsior L. and recalcitrant Quercus robur L.) and to soil CO2 fluxes were measured. Both moisture conditions and litter type influenced the functioning of the invertebrate assemblages, which was greater in high moisture conditions compared with low moisture conditions and on good quality vs. recalcitrant litter. In high moisture conditions, all macrofauna assemblages functioned at equal rates, whereas in low moisture conditions there were pronounced differences in litter mass loss among the assemblages. This indicates that species identity and assemblage composition are more important when moisture is limited. We suggest that complementarity between macrofauna species may mitigate the reduced functioning of some species, highlighting the importance of maintaining macrofauna species richness.

  12. Roles of benthic algae in the structure, function, and assessment of stream ecosystems affected by acid mine drainage.

    PubMed

    Smucker, Nathan J; Drerup, Samuel A; Vis, Morgan L

    2014-06-01

    Tens of thousands of stream kilometers worldwide are degraded by a legacy of acid loads, high metal concentrations, and altered habitat caused by acid mine drainage (AMD) from abandoned underground and surface mines. As the primary production base in streams, the condition of algal-dominated periphyton communities is particularly important to nutrient cycling, energy flow, and higher trophic levels. Here, we synthesize current knowledge regarding how AMD-associated stressors affect (i) algal communities and their use as ecological indicators, (ii) their functional roles in stream ecosystems, and (iii) how these findings inform management decisions and evaluation of restoration effectiveness. A growing body of research has found ecosystem simplification caused by AMD stressors. Species diversity declines, productivity decreases, and less efficient nutrient uptake and retention occur as AMD severity increases. New monitoring approaches, indices of biological condition, and attributes of algal community structure and function effectively assess AMD severity and effectiveness of management practices. Measures of ecosystem processes, such as nutrient uptake rates, extracellular enzyme activities, and metabolism, are increasingly being used as assessment tools, but remain in their infancy relative to traditional community structure-based approaches. The continued development, testing, and implementation of functional measures and their use alongside community structure metrics will further advance assessments, inform management decisions, and foster progress toward restoration goals. Algal assessments will have important roles in making progress toward improving and sustaining the water quality, ecological condition, and ecosystem services of streams in regions affected by the legacy of unregulated coal mining. PMID:26988317

  13. Foundation species loss affects vegetation structure more than ecosystem function in a northeastern USA forest.

    PubMed

    Orwig, David A; Barker Plotkin, Audrey A; Davidson, Eric A; Lux, Heidi; Savage, Kathleen E; Ellison, Aaron M

    2013-01-01

    patterns observed consistently in region-wide studies of adelgid-infested hemlock stands. Mechanisms of T. canadensis loss determine rates, magnitudes, and trajectories of ecological changes in hemlock forests. Logging causes abrupt, large changes in vegetation structure whereas girdling (and by inference, A. tsugae) causes sustained, smaller changes. Ecosystem processes depend more on vegetation cover per se than on species composition. We conclude that the loss of this late-successional foundation species will have long-lasting impacts on forest structure but subtle impacts on ecosystem function. PMID:23638378

  14. A trait-based framework for predicting when and where microbial adaptation to climate change will affect ecosystem functioning

    USGS Publications Warehouse

    Wallenstein, Matthew D.; Hall, Edward K.

    2012-01-01

    As the earth system changes in response to human activities, a critical objective is to predict how biogeochemical process rates (e.g. nitrification, decomposition) and ecosystem function (e.g. net ecosystem productivity) will change under future conditions. A particular challenge is that the microbial communities that drive many of these processes are capable of adapting to environmental change in ways that alter ecosystem functioning. Despite evidence that microbes can adapt to temperature, precipitation regimes, and redox fluctuations, microbial communities are typically not optimally adapted to their local environment. For example, temperature optima for growth and enzyme activity are often greater than in situ temperatures in their environment. Here we discuss fundamental constraints on microbial adaptation and suggest specific environments where microbial adaptation to climate change (or lack thereof) is most likely to alter ecosystem functioning. Our framework is based on two principal assumptions. First, there are fundamental ecological trade-offs in microbial community traits that occur across environmental gradients (in time and space). These trade-offs result in shifting of microbial function (e.g. ability to take up resources at low temperature) in response to adaptation of another trait (e.g. limiting maintenance respiration at high temperature). Second, the mechanism and level of microbial community adaptation to changing environmental parameters is a function of the potential rate of change in community composition relative to the rate of environmental change. Together, this framework provides a basis for developing testable predictions about how the rate and degree of microbial adaptation to climate change will alter biogeochemical processes in aquatic and terrestrial ecosystems across the planet.

  15. Ash in fire affected ecosystems

    NASA Astrophysics Data System (ADS)

    Pereira, Paulo; Jordan, Antonio; Cerda, Artemi; Martin, Deborah

    2015-04-01

    Ash in fire affected ecosystems Ash lefts an important footprint in the ecosystems and has a key role in the immediate period after the fire (Bodi et al., 2014; Pereira et al., 2015). It is an important source of nutrients for plant recover (Pereira et al., 2014a), protects soil from erosion and controls soil hydrological process as runoff, infiltration and water repellency (Cerda and Doerr, 2008; Bodi et al., 2012, Pereira et al., 2014b). Despite the recognition of ash impact and contribution to ecosystems recuperation, it is assumed that we still have little knowledge about the implications of ash in fire affected areas. Regarding this situation we wanted to improve our knowledge in this field and understand the state of the research about fire ash around world. The special issue about "The role of ash in fire affected ecosystems" currently in publication in CATENA born from the necessity of joint efforts, identify research gaps, and discuss future cooperation in this interdisciplinary field. This is the first special issue about fire ash in the international literature. In total it will be published 10 papers focused in different aspects of the impacts of ash in fire affected ecosystems from several parts of the world: • Fire reconstruction using charcoal particles (Burjachs and Espositio, in press) • Ash slurries impact on rheological properties of Runoff (Burns and Gabet, in press) • Methods to analyse ash conductivity and sorbtivity in the laboratory and in the field (Balfour et al., in press) • Termogravimetric and hydrological properties of ash (Dlapa et al. in press) • Effects of ash cover in water infiltration (Leon et al., in press) • Impact of ash in volcanic soils (Dorta Almenar et al., in press; Escuday et al., in press) • Ash PAH and Chemical extracts (Silva et al., in press) • Microbiology (Barreiro et al., in press; Lombao et al., in press) We believe that this special issue will contribute importantly to the better understanding of

  16. Ash in fire affected ecosystems

    NASA Astrophysics Data System (ADS)

    Pereira, Paulo; Jordan, Antonio; Cerda, Artemi; Martin, Deborah

    2015-04-01

    Ash in fire affected ecosystems Ash lefts an important footprint in the ecosystems and has a key role in the immediate period after the fire (Bodi et al., 2014; Pereira et al., 2015). It is an important source of nutrients for plant recover (Pereira et al., 2014a), protects soil from erosion and controls soil hydrological process as runoff, infiltration and water repellency (Cerda and Doerr, 2008; Bodi et al., 2012, Pereira et al., 2014b). Despite the recognition of ash impact and contribution to ecosystems recuperation, it is assumed that we still have little knowledge about the implications of ash in fire affected areas. Regarding this situation we wanted to improve our knowledge in this field and understand the state of the research about fire ash around world. The special issue about "The role of ash in fire affected ecosystems" currently in publication in CATENA born from the necessity of joint efforts, identify research gaps, and discuss future cooperation in this interdisciplinary field. This is the first special issue about fire ash in the international literature. In total it will be published 10 papers focused in different aspects of the impacts of ash in fire affected ecosystems from several parts of the world: • Fire reconstruction using charcoal particles (Burjachs and Espositio, in press) • Ash slurries impact on rheological properties of Runoff (Burns and Gabet, in press) • Methods to analyse ash conductivity and sorbtivity in the laboratory and in the field (Balfour et al., in press) • Termogravimetric and hydrological properties of ash (Dlapa et al. in press) • Effects of ash cover in water infiltration (Leon et al., in press) • Impact of ash in volcanic soils (Dorta Almenar et al., in press; Escuday et al., in press) • Ash PAH and Chemical extracts (Silva et al., in press) • Microbiology (Barreiro et al., in press; Lombao et al., in press) We believe that this special issue will contribute importantly to the better understanding of

  17. Factors Affecting Trophic Control of Community Structure and Ecosystem Functioning in Experimental Mesocosms of Seagrass (Zostera marina L.)

    NASA Astrophysics Data System (ADS)

    Lefcheck, J.; Duffy, J.

    2008-12-01

    Nutrient loading of coastal and estuarine waters threatens seagrass communities by promoting the growth of micro- and macroalgae, which then reduce the availability of light and nutrients. However, populations of invertebrate mesograzers are able to mitigate the negative impact of eutrophication through top-down control. We performed a factorial mesocosm experiment to examine the interactive relationships between light, nutrients, and mesograzer presence in structuring experimental ecosystems of eelgrass (Zostera marina). We found that mesograzer presence strongly reduced epiphytic algal biomass in every case, which remains consistent with previous mesocosm studies. We also observed a synergistic light-by-nutrient interaction that enhanced both epiphyte biomass and mesograzer abundance. The timing of this relationship is suggestive of weaker bottom-up control. Unlike previous studies, we found that light alone rarely affected either epiphyte biomass or mesograzer abundance. We believe that this result may be due to a combination of macroalgal shading and persistent grazing. Further processing of primary and secondary producer biomasses and elemental ratios, as well as the completion of feeding assays to gauge mesograzer feeding rates on different types of algae, will serve to reinforce these conclusions and to better define the relationship between these factors.

  18. Avian ecosystem functions are influenced by small mammal ecosystem engineering

    PubMed Central

    2013-01-01

    Background Birds are important mobile link species that contribute to landscape-scale patterns by means of pollination, seed dispersal, and predation. Birds are often associated with habitats modified by small mammal ecosystem engineers. We investigated whether birds prefer to forage on degu (Octodon degus) runways by comparing their foraging effort across sites with a range of runway densities, including sites without runways. We measured granivory by granivorous and omnivorous birds at Rinconada de Maipú, central Chile. As a measure of potential bird foraging on insects, we sampled invertebrate prey richness and abundance across the same sites. We then quantified an index of plot-scale functional diversity due to avian foraging at the patch scale. Results We recorded that birds found food sources sooner and ate more at sites with higher densities of degu runways, cururo mounds, trees, and fewer shrubs. These sites also had higher invertebrate prey richness but lower invertebrate prey abundance. This implies that omnivorous birds, and possibly insectivorous birds, forage for invertebrates in the same plots with high degu runway densities where granivory takes place. In an exploratory analysis we also found that plot-scale functional diversity for four avian ecosystem functions were moderately to weakly correllated to expected ecosystem function outcomes at the plot scale. Conclusions Degu ecosystem engineering affects the behavior of avian mobile link species and is thus correlated with ecosystem functioning at relatively small spatial scales. PMID:24359802

  19. Do high levels of diffuse and chronic metal pollution in sediments of Rhine and Meuse floodplains affect structure and functioning of terrestrial ecosystems?

    PubMed

    Rozema, Jelte; Notten, Martje J M; Aerts, Rien; van Gestel, Cornelis A M; Hobbelen, Peter H F; Hamers, Timo H M

    2008-12-01

    This paper (re)considers the question if chronic and diffuse heavy metal pollution (cadmium, copper, lead and zinc) affects the structure and functioning of terrestrial ecosystems of Biesbosch National Park, the floodplain area of rivers Meuse and Rhine. To reach this aim, we integrated the results of three projects on: 1. the origin, transfer and effects of heavy metals in a soil-plant-snail food chain; 2. the impact of bioavailability on effects of heavy metals on the structure and functioning of detritivorous communities; 3. the risk assessment of heavy metals for an herbivorous and a carnivorous small mammal food chain. Metal pollution levels of the Biesbosch floodplain soils are high. The bioavailability of metals in the soils is low, causing low metal levels in plant leaves. Despite this, metal concentrations in soil dwelling detritivores and in land snails at polluted locations are elevated in comparison to animals from 'non-polluted' reference sites. However, no adverse effects on ecosystem structure (species richness, density, biomass) and functioning (litter decomposition, leaf consumption, reproduction) have been found. Sediment metal pollution may pose a risk to the carnivorous small mammal food chain, in which earthworms with elevated metal concentrations are eaten by the common shrew. Additional measurements near an active metal smelter, however, show reduced leaf consumption rates and reduced reproduction by terrestrial snails, reflecting elevated metal bioavailability at this site. Since future management may also comprise reintroduction of tidal action in the Biesbosch area, changes in metal bioavailability, and as a consequence future ecosystem effects, cannot be excluded.

  20. Do high levels of diffuse and chronic metal pollution in sediments of Rhine and Meuse floodplains affect structure and functioning of terrestrial ecosystems?

    PubMed

    Rozema, Jelte; Notten, Martje J M; Aerts, Rien; van Gestel, Cornelis A M; Hobbelen, Peter H F; Hamers, Timo H M

    2008-12-01

    This paper (re)considers the question if chronic and diffuse heavy metal pollution (cadmium, copper, lead and zinc) affects the structure and functioning of terrestrial ecosystems of Biesbosch National Park, the floodplain area of rivers Meuse and Rhine. To reach this aim, we integrated the results of three projects on: 1. the origin, transfer and effects of heavy metals in a soil-plant-snail food chain; 2. the impact of bioavailability on effects of heavy metals on the structure and functioning of detritivorous communities; 3. the risk assessment of heavy metals for an herbivorous and a carnivorous small mammal food chain. Metal pollution levels of the Biesbosch floodplain soils are high. The bioavailability of metals in the soils is low, causing low metal levels in plant leaves. Despite this, metal concentrations in soil dwelling detritivores and in land snails at polluted locations are elevated in comparison to animals from 'non-polluted' reference sites. However, no adverse effects on ecosystem structure (species richness, density, biomass) and functioning (litter decomposition, leaf consumption, reproduction) have been found. Sediment metal pollution may pose a risk to the carnivorous small mammal food chain, in which earthworms with elevated metal concentrations are eaten by the common shrew. Additional measurements near an active metal smelter, however, show reduced leaf consumption rates and reduced reproduction by terrestrial snails, reflecting elevated metal bioavailability at this site. Since future management may also comprise reintroduction of tidal action in the Biesbosch area, changes in metal bioavailability, and as a consequence future ecosystem effects, cannot be excluded. PMID:18707753

  1. How will ocean acidification affect Baltic sea ecosystems? an assessment of plausible impacts on key functional groups.

    PubMed

    Havenhand, Jonathan N

    2012-09-01

    Increasing partial pressure of atmospheric CO₂ is causing ocean pH to fall-a process known as 'ocean acidification'. Scenario modeling suggests that ocean acidification in the Baltic Sea may cause a ≤ 3 times increase in acidity (reduction of 0.2-0.4 pH units) by the year 2100. The responses of most Baltic Sea organisms to ocean acidification are poorly understood. Available data suggest that most species and ecologically important groups in the Baltic Sea food web (phytoplankton, zooplankton, macrozoobenthos, cod and sprat) will be robust to the expected changes in pH. These conclusions come from (mostly) single-species and single-factor studies. Determining the emergent effects of ocean acidification on the ecosystem from such studies is problematic, yet very few studies have used multiple stressors and/or multiple trophic levels. There is an urgent need for more data from Baltic Sea populations, particularly from environmentally diverse regions and from controlled mesocosm experiments. In the absence of such information it is difficult to envision the likely effects of future ocean acidification on Baltic Sea species and ecosystems.

  2. Eight questions about invasions and ecosystem functioning.

    PubMed

    Strayer, David L

    2012-10-01

    I pose eight questions central to understanding how biological invasions affect ecosystems, assess progress towards answering those questions and suggest ways in which progress might be made. The questions concern the frequency with which invasions affect ecosystems; the circumstances under which ecosystem change is most likely; the functions that are most often affected by invaders; the relationships between changes to ecosystems, communities, and populations; the long-term responses of ecosystems to invasions; interactions between biological invasions and other anthropogenic activities and the difficulty of managing undesirable impacts of non-native species. Some questions have been answered satisfactorily, others require more data and thought, and others might benefit from being reformulated or abandoned. Actions that might speed progress include careful development of trait-based approaches; strategic collection and publication of new data, including more frequent publication of negative results; replacement of expert opinion with hard data where needed; careful consideration of whether questions really need to be answered, especially in cases where answers are being provided for managers and policy-makers; explicit attention to and testing of the domains of theories; integrating invasions better into an ecosystem context; and remembering that our predictive ability is limited and will remain so for the foreseeable future.

  3. Obscuring ecosystem function with application of the ecosystem services concept.

    PubMed

    Peterson, Markus J; Hall, Damon M; Feldpausch-Parker, Andrea M; Peterson, Tarla Rai

    2010-02-01

    Conservationists commonly have framed ecological concerns in economic terms to garner political support for conservation and to increase public interest in preserving global biodiversity. Beginning in the early 1980s, conservation biologists adapted neoliberal economics to reframe ecosystem functions and related biodiversity as ecosystem services to humanity. Despite the economic success of programs such as the Catskill/Delaware watershed management plan in the United States and the creation of global carbon exchanges, today's marketplace often fails to adequately protect biodiversity. We used a Marxist critique to explain one reason for this failure and to suggest a possible, if partial, response. Reframing ecosystem functions as economic services does not address the political problem of commodification. Just as it obscures the labor of human workers, commodification obscures the importance of the biota (ecosystem workers) and related abiotic factors that contribute to ecosystem functions. This erasure of work done by ecosystems impedes public understanding of biodiversity. Odum and Odum's radical suggestion to use the language of ecosystems (i.e., emergy or energy memory) to describe economies, rather than using the language of economics (i.e., services) to describe ecosystems, reverses this erasure of the ecosystem worker. Considering the current dominance of economic forces, however, implementing such solutions would require social changes similar in magnitude to those that occurred during the 1960s. Niklas Luhmann argues that such substantive, yet rapid, social change requires synergy among multiple societal function systems (i.e., economy, education, law, politics, religion, science), rather than reliance on a single social sphere, such as the economy. Explicitly presenting ecosystem services as discreet and incomplete aspects of ecosystem functions not only allows potential economic and environmental benefits associated with ecosystem services, but also

  4. Food-web constraints on biodiversity–ecosystem functioning relationships

    PubMed Central

    Thébault, Elisa; Loreau, Michel

    2003-01-01

    The consequences of biodiversity loss for ecosystem functioning and ecosystem services have aroused considerable interest during the past decade. Recent work has focused mainly on the impact of species diversity within single trophic levels, both experimentally and theoretically. Experiments have usually showed increased plant biomass and productivity with increasing plant diversity. Changes in biodiversity, however, may affect ecosystem processes through trophic interactions among species as well. An important current challenge is to understand how these trophic interactions affect the relationship between biodiversity and ecosystem functioning. Here we present a mechanistic model of an ecosystem with multiple trophic levels in which plants compete for a limiting soil nutrient. In contrast to previous studies that focused on single trophic levels, we show that plant biomass does not always increase with plant diversity and that changes in biodiversity can lead to complex if predictable changes in ecosystem processes. Our analysis demonstrates that food-web structure can profoundly influence ecosystem properties. PMID:14638942

  5. Effects of red-backed salamanders on ecosystem functions.

    PubMed

    Hocking, Daniel J; Babbitt, Kimberly J

    2014-01-01

    Ecosystems provide a vast array of services for human societies, but understanding how various organisms contribute to the functions that maintain these services remains an important ecological challenge. Predators can affect ecosystem functions through a combination of top-down trophic cascades and bottom-up effects on nutrient dynamics. As the most abundant vertebrate predator in many eastern US forests, woodland salamanders (Plethodon spp.) likely affect ecosystems functions. We examined the effects of red-backed salamanders (Plethodon cinereus) on a variety of forest ecosystem functions using a combined approach of large-scale salamander removals (314-m(2) plots) and small-scale enclosures (2 m(2)) where we explicitly manipulated salamander density (0, 0.5, 1, 2, 4 m(-2)). In these experiments, we measured the rates of litter and wood decomposition, potential nitrogen mineralization and nitrification rates, acorn germination, and foliar insect damage on red oak seedlings. Across both experimental venues, we found no significant effect of red-backed salamanders on any of the ecosystem functions. We also found no effect of salamanders on intraguild predator abundance (carabid beetles, centipedes, spiders). Our study adds to the already conflicting evidence on effects of red-backed salamander and other amphibians on terrestrial ecosystem functions. It appears likely that the impact of terrestrial amphibians on ecosystem functions is context dependent. Future research would benefit from explicitly examining terrestrial amphibian effects on ecosystem functions under a variety of environmental conditions and in different forest types.

  6. Effects of Red-Backed Salamanders on Ecosystem Functions

    PubMed Central

    Hocking, Daniel J.; Babbitt, Kimberly J.

    2014-01-01

    Ecosystems provide a vast array of services for human societies, but understanding how various organisms contribute to the functions that maintain these services remains an important ecological challenge. Predators can affect ecosystem functions through a combination of top-down trophic cascades and bottom-up effects on nutrient dynamics. As the most abundant vertebrate predator in many eastern US forests, woodland salamanders (Plethodon spp.) likely affect ecosystems functions. We examined the effects of red-backed salamanders (Plethodon cinereus) on a variety of forest ecosystem functions using a combined approach of large-scale salamander removals (314-m2 plots) and small-scale enclosures (2 m2) where we explicitly manipulated salamander density (0, 0.5, 1, 2, 4 m−2). In these experiments, we measured the rates of litter and wood decomposition, potential nitrogen mineralization and nitrification rates, acorn germination, and foliar insect damage on red oak seedlings. Across both experimental venues, we found no significant effect of red-backed salamanders on any of the ecosystem functions. We also found no effect of salamanders on intraguild predator abundance (carabid beetles, centipedes, spiders). Our study adds to the already conflicting evidence on effects of red-backed salamander and other amphibians on terrestrial ecosystem functions. It appears likely that the impact of terrestrial amphibians on ecosystem functions is context dependent. Future research would benefit from explicitly examining terrestrial amphibian effects on ecosystem functions under a variety of environmental conditions and in different forest types. PMID:24466269

  7. Effects of red-backed salamanders on ecosystem functions.

    PubMed

    Hocking, Daniel J; Babbitt, Kimberly J

    2014-01-01

    Ecosystems provide a vast array of services for human societies, but understanding how various organisms contribute to the functions that maintain these services remains an important ecological challenge. Predators can affect ecosystem functions through a combination of top-down trophic cascades and bottom-up effects on nutrient dynamics. As the most abundant vertebrate predator in many eastern US forests, woodland salamanders (Plethodon spp.) likely affect ecosystems functions. We examined the effects of red-backed salamanders (Plethodon cinereus) on a variety of forest ecosystem functions using a combined approach of large-scale salamander removals (314-m(2) plots) and small-scale enclosures (2 m(2)) where we explicitly manipulated salamander density (0, 0.5, 1, 2, 4 m(-2)). In these experiments, we measured the rates of litter and wood decomposition, potential nitrogen mineralization and nitrification rates, acorn germination, and foliar insect damage on red oak seedlings. Across both experimental venues, we found no significant effect of red-backed salamanders on any of the ecosystem functions. We also found no effect of salamanders on intraguild predator abundance (carabid beetles, centipedes, spiders). Our study adds to the already conflicting evidence on effects of red-backed salamander and other amphibians on terrestrial ecosystem functions. It appears likely that the impact of terrestrial amphibians on ecosystem functions is context dependent. Future research would benefit from explicitly examining terrestrial amphibian effects on ecosystem functions under a variety of environmental conditions and in different forest types. PMID:24466269

  8. Neotropical Amphibian Declines Affect Stream Ecosystem Properties

    NASA Astrophysics Data System (ADS)

    Connelly, S.; Pringle, C. M.; Bixby, R. J.; Whiles, M. R.; Lips, K. R.; Brenes, R.; Colon-Gaud, J. C.; Kilham, S.; Hunte-Brown, M.

    2005-05-01

    Global declines of amphibians are well documented, yet effects of these dramatic losses on ecosystem structure and function are poorly understood. As part of a larger collaborative project, we compared two upland Panamanian streams. Both streams are biologically and geologically similar; however, one stream (Fortuna) has recently experienced almost complete extirpation of stream-dwelling frogs, while the other (Cope) still has intact populations. We experimentally excluded tadpoles from localized areas in each stream. We then compared chlorophyll a, algal community composition, ash-free dry mass (AFDM), inorganic matter, and insect assemblages in control and exclusion areas. Additionally, we sampled the natural substrate of both streams monthly for chlorophyll a, algal community composition, AFDM, and inorganic matter. At Cope, chlorophyll a, AFDM, and inorganic matter were greater in areas where tadpoles were excluded than in their presence. Numbers of dominant algal species (e.g., Nupela praecipua and Eunotia siolii) were greater in the exclusion versus control treatments. Monthly sampling of natural substrate indicated higher chlorophyll a and AFDM at Cope compared to Fortuna. Our data suggest that stream-dwelling anuran larvae have significant impacts on algal communities. These results also have implications for predicting the relevance of short-term experimental manipulations to long-term, whole-stream processes.

  9. Biodiversity and Resilience of Ecosystem Functions.

    PubMed

    Oliver, Tom H; Heard, Matthew S; Isaac, Nick J B; Roy, David B; Procter, Deborah; Eigenbrod, Felix; Freckleton, Rob; Hector, Andy; Orme, C David L; Petchey, Owen L; Proença, Vânia; Raffaelli, David; Suttle, K Blake; Mace, Georgina M; Martín-López, Berta; Woodcock, Ben A; Bullock, James M

    2015-11-01

    Accelerating rates of environmental change and the continued loss of global biodiversity threaten functions and services delivered by ecosystems. Much ecosystem monitoring and management is focused on the provision of ecosystem functions and services under current environmental conditions, yet this could lead to inappropriate management guidance and undervaluation of the importance of biodiversity. The maintenance of ecosystem functions and services under substantial predicted future environmental change (i.e., their 'resilience') is crucial. Here we identify a range of mechanisms underpinning the resilience of ecosystem functions across three ecological scales. Although potentially less important in the short term, biodiversity, encompassing variation from within species to across landscapes, may be crucial for the longer-term resilience of ecosystem functions and the services that they underpin.

  10. Functional traits, the phylogeny of function, and ecosystem service vulnerability

    PubMed Central

    Díaz, Sandra; Purvis, Andy; Cornelissen, Johannes H C; Mace, Georgina M; Donoghue, Michael J; Ewers, Robert M; Jordano, Pedro; Pearse, William D

    2013-01-01

    People depend on benefits provided by ecological systems. Understanding how these ecosystem services – and the ecosystem properties underpinning them – respond to drivers of change is therefore an urgent priority. We address this challenge through developing a novel risk-assessment framework that integrates ecological and evolutionary perspectives on functional traits to determine species’ effects on ecosystems and their tolerance of environmental changes. We define Specific Effect Function (SEF) as the per-gram or per capita capacity of a species to affect an ecosystem property, and Specific Response Function (SRF) as the ability of a species to maintain or enhance its population as the environment changes. Our risk assessment is based on the idea that the security of ecosystem services depends on how effects (SEFs) and tolerances (SRFs) of organisms – which both depend on combinations of functional traits – correlate across species and how they are arranged on the species’ phylogeny. Four extreme situations are theoretically possible, from minimum concern when SEF and SRF are neither correlated nor show a phylogenetic signal, to maximum concern when they are negatively correlated (i.e., the most important species are the least tolerant) and phylogenetically patterned (lacking independent backup). We illustrate the assessment with five case studies, involving both plant and animal examples. However, the extent to which the frequency of the four plausible outcomes, or their intermediates, apply more widely in real-world ecological systems is an open question that needs empirical evidence, and suggests a research agenda at the interface of evolutionary biology and ecosystem ecology. PMID:24101986

  11. Richness, biomass, and nutrient content of a wetland macrophyte community affect soil nitrogen cycling in a diversity-ecosystem functioning experiment

    USGS Publications Warehouse

    Korol, Alicia R.; Ahn, Changwoo; Noe, Gregory

    2016-01-01

    The development of soil nitrogen (N) cycling in created wetlands promotes the maturation of multiple biogeochemical cycles necessary for ecosystem functioning. This development proceeds from gradual changes in soil physicochemical properties and influential characteristics of the plant community, such as competitive behavior, phenology, productivity, and nutrient composition. In the context of a 2-year diversity experiment in freshwater mesocosms (0, 1, 2, 3, or 4 richness levels), we assessed the direct and indirect impacts of three plant community characteristics – species richness, total biomass, and tissue N concentration – on three processes in the soil N cycle – soil net ammonification, net nitrification, and denitrification potentials. Species richness had a positive effect on net ammonification potential (NAP) through higher redox potentials and likely faster microbial respiration. All NAP rates were negative, however, due to immobilization and high rates of ammonium removal. Net nitrification was inhibited at higher species richness without mediation from the measured soil properties. Higher species richness also inhibited denitrification potential through increased redox potential and decreased nitrification. Both lower biomass and/or higher tissue ratios of carbon to nitrogen, characteristics indicative of the two annual plants, were shown to have stimulatory effects on all three soil N processes. The two mediating physicochemical links between the young macrophyte community and microbial N processes were soil redox potential and temperature. Our results suggest that early-successional annual plant communities play an important role in the development of ecosystem N multifunctionality in newly created wetland soils.

  12. Nutrient recycling affects autotroph and ecosystem stoichiometry.

    PubMed

    Ballantyne, Ford; Menge, Duncan N L; Ostling, Annette; Hosseini, Parviez

    2008-04-01

    Stoichiometric nutrient ratios are the consequence of myriad interacting processes, both biotic and abiotic. Theoretical explanations for autotroph stoichiometry have focused on species' nutrient requirements but have not addressed the role of nutrient availability in determining autotroph stoichiometry. Remineralization of organic N and P supplies a significant fraction of inorganic N and P to autotrophs, making nutrient recycling a potentially important process influencing autotroph stoichiometry. To quantitatively investigate the relationship between available N and P, autotroph N:P, and nutrient recycling, we analyze a stoichiometrically explicit model of autotroph growth, incorporating Michaelis-Menten-Monod nutrient uptake kinetics, Droop growth, and Liebig's law of the minimum. If autotroph growth is limited by a single nutrient, increased recycling of the limiting nutrient pushes autotrophs toward colimitation and alters both autotroph and environmental stoichiometry. We derive a steady state relationship between input stoichiometry, autotroph N:P, and the stoichiometry of organic losses that allows us to estimate the relative recycling of N to P within an ecosystem. We then estimate relative N and P recycling for a marine, an aquatic, and two terrestrial ecosystems. Preferential P recycling, in conjunction with greater relative P retention at the organismal and ecosystem levels, presents a strong case for the importance of P to biomass production across ecosystems.

  13. Plant ecology. Anthropogenic environmental changes affect ecosystem stability via biodiversity.

    PubMed

    Hautier, Yann; Tilman, David; Isbell, Forest; Seabloom, Eric W; Borer, Elizabeth T; Reich, Peter B

    2015-04-17

    Human-driven environmental changes may simultaneously affect the biodiversity, productivity, and stability of Earth's ecosystems, but there is no consensus on the causal relationships linking these variables. Data from 12 multiyear experiments that manipulate important anthropogenic drivers, including plant diversity, nitrogen, carbon dioxide, fire, herbivory, and water, show that each driver influences ecosystem productivity. However, the stability of ecosystem productivity is only changed by those drivers that alter biodiversity, with a given decrease in plant species numbers leading to a quantitatively similar decrease in ecosystem stability regardless of which driver caused the biodiversity loss. These results suggest that changes in biodiversity caused by drivers of environmental change may be a major factor determining how global environmental changes affect ecosystem stability.

  14. Ecosystem Function: Cyanobacteria Solutions, A Missed Opportunity?

    EPA Science Inventory

    Stream and wetland riparian functions integrate the relationships between species, their habitats and fostering ecosystem resilience, which is critical to resilience – i.e., ensuring long-term sustainability. These relationships are dependent on the drivers of ecological functio...

  15. Linking plant and ecosystem functional biogeography

    PubMed Central

    Reichstein, Markus; Bahn, Michael; Mahecha, Miguel D.; Kattge, Jens; Baldocchi, Dennis D.

    2014-01-01

    Classical biogeographical observations suggest that ecosystems are strongly shaped by climatic constraints in terms of their structure and function. On the other hand, vegetation function feeds back on the climate system via biosphere–atmosphere exchange of matter and energy. Ecosystem-level observations of this exchange reveal very large functional biogeographical variation of climate-relevant ecosystem functional properties related to carbon and water cycles. This variation is explained insufficiently by climate control and a classical plant functional type classification approach. For example, correlations between seasonal carbon-use efficiency and climate or environmental variables remain below 0.6, leaving almost 70% of variance unexplained. We suggest that a substantial part of this unexplained variation of ecosystem functional properties is related to variations in plant and microbial traits. Therefore, to progress with global functional biogeography, we should seek to understand the link between organismic traits and flux-derived ecosystem properties at ecosystem observation sites and the spatial variation of vegetation traits given geoecological covariates. This understanding can be fostered by synergistic use of both data-driven and theory-driven ecological as well as biophysical approaches. PMID:25225392

  16. Extinction order and altered community structure rapidly disrupt ecosystem functioning.

    PubMed

    Larsen, Trond H; Williams, Neal M; Kremen, Claire

    2005-05-01

    By causing extinctions and altering community structure, anthropogenic disturbances can disrupt processes that maintain ecosystem integrity. However, the relationship between community structure and ecosystem functioning in natural systems is poorly understood. Here we show that habitat loss appeared to disrupt ecosystem functioning by affecting extinction order, species richness and abundance. We studied pollination by bees in a mosaic of agricultural and natural habitats in California and dung burial by dung beetles on recently created islands in Venezuela. We found that large-bodied bee and beetle species tended to be both most extinction-prone and most functionally efficient, contributing to rapid functional loss. Simulations confirmed that extinction order led to greater disruption of function than predicted by random species loss. Total abundance declined with richness and also appeared to contribute to loss of function. We demonstrate conceptually and empirically how the non-random response of communities to disturbance can have unexpectedly large functional consequences.

  17. INVASIVE PLANTS HARBOR HUNGRY DETRITIVORES THAT ALTER ECOSYSTEM FUNCTION

    EPA Science Inventory

    Ecosystems are expected to function more efficiently in response to a diverse community of inhabitants. However, biological invasions may change expected relationships between ecosystem function and diversity. We observed increased decomposition, a measure of ecosystem function...

  18. Effects of species evenness and dominant species identity on multiple ecosystem functions in model grassland communities.

    PubMed

    Orwin, Kate H; Ostle, Nick; Wilby, Andrew; Bardgett, Richard D

    2014-03-01

    Ecosystems provide multiple services upon which humans depend. Understanding the drivers of the ecosystem functions that support these services is therefore important. Much research has investigated how species richness influences functioning, but we lack knowledge of how other community attributes affect ecosystem functioning. Species evenness, species spatial arrangement, and the identity of dominant species are three attributes that could affect ecosystem functioning, by altering the relative abundance of functional traits and the probability of synergistic species interactions such as facilitation and complementary resource use. We tested the effect of these three community attributes and their interactions on ecosystem functions over a growing season, using model grassland communities consisting of three plant species from three functional groups: a grass (Anthoxanthum odoratum), a forb (Plantago lanceolata), and a N-fixing forb (Lotus corniculatus). We measured multiple ecosystem functions that support ecosystem services, including ecosystem gas exchange, water retention, C and N loss in leachates, and plant biomass production. Species evenness and dominant species identity strongly influenced the ecosystem functions measured, but spatial arrangement had few effects. By the end of the growing season, evenness consistently enhanced ecosystem functioning and this effect occurred regardless of dominant species identity. The identity of the dominant species under which the highest level of functioning was attained varied across the growing season. Spatial arrangement had the weakest effect on functioning, but interacted with dominant species identity to affect some functions. Our results highlight the importance of understanding the role of multiple community attributes in driving ecosystem functioning. PMID:24213721

  19. Effects of species evenness and dominant species identity on multiple ecosystem functions in model grassland communities.

    PubMed

    Orwin, Kate H; Ostle, Nick; Wilby, Andrew; Bardgett, Richard D

    2014-03-01

    Ecosystems provide multiple services upon which humans depend. Understanding the drivers of the ecosystem functions that support these services is therefore important. Much research has investigated how species richness influences functioning, but we lack knowledge of how other community attributes affect ecosystem functioning. Species evenness, species spatial arrangement, and the identity of dominant species are three attributes that could affect ecosystem functioning, by altering the relative abundance of functional traits and the probability of synergistic species interactions such as facilitation and complementary resource use. We tested the effect of these three community attributes and their interactions on ecosystem functions over a growing season, using model grassland communities consisting of three plant species from three functional groups: a grass (Anthoxanthum odoratum), a forb (Plantago lanceolata), and a N-fixing forb (Lotus corniculatus). We measured multiple ecosystem functions that support ecosystem services, including ecosystem gas exchange, water retention, C and N loss in leachates, and plant biomass production. Species evenness and dominant species identity strongly influenced the ecosystem functions measured, but spatial arrangement had few effects. By the end of the growing season, evenness consistently enhanced ecosystem functioning and this effect occurred regardless of dominant species identity. The identity of the dominant species under which the highest level of functioning was attained varied across the growing season. Spatial arrangement had the weakest effect on functioning, but interacted with dominant species identity to affect some functions. Our results highlight the importance of understanding the role of multiple community attributes in driving ecosystem functioning.

  20. Megafauna and ecosystem function from the Pleistocene to the Anthropocene.

    PubMed

    Malhi, Yadvinder; Doughty, Christopher E; Galetti, Mauro; Smith, Felisa A; Svenning, Jens-Christian; Terborgh, John W

    2016-01-26

    Large herbivores and carnivores (the megafauna) have been in a state of decline and extinction since the Late Pleistocene, both on land and more recently in the oceans. Much has been written on the timing and causes of these declines, but only recently has scientific attention focused on the consequences of these declines for ecosystem function. Here, we review progress in our understanding of how megafauna affect ecosystem physical and trophic structure, species composition, biogeochemistry, and climate, drawing on special features of PNAS and Ecography that have been published as a result of an international workshop on this topic held in Oxford in 2014. Insights emerging from this work have consequences for our understanding of changes in biosphere function since the Late Pleistocene and of the functioning of contemporary ecosystems, as well as offering a rationale and framework for scientifically informed restoration of megafaunal function where possible and appropriate.

  1. Megafauna and ecosystem function from the Pleistocene to the Anthropocene.

    PubMed

    Malhi, Yadvinder; Doughty, Christopher E; Galetti, Mauro; Smith, Felisa A; Svenning, Jens-Christian; Terborgh, John W

    2016-01-26

    Large herbivores and carnivores (the megafauna) have been in a state of decline and extinction since the Late Pleistocene, both on land and more recently in the oceans. Much has been written on the timing and causes of these declines, but only recently has scientific attention focused on the consequences of these declines for ecosystem function. Here, we review progress in our understanding of how megafauna affect ecosystem physical and trophic structure, species composition, biogeochemistry, and climate, drawing on special features of PNAS and Ecography that have been published as a result of an international workshop on this topic held in Oxford in 2014. Insights emerging from this work have consequences for our understanding of changes in biosphere function since the Late Pleistocene and of the functioning of contemporary ecosystems, as well as offering a rationale and framework for scientifically informed restoration of megafaunal function where possible and appropriate. PMID:26811442

  2. Megafauna and ecosystem function from the Pleistocene to the Anthropocene

    PubMed Central

    Malhi, Yadvinder; Doughty, Christopher E.; Galetti, Mauro; Smith, Felisa A.; Svenning, Jens-Christian; Terborgh, John W.

    2016-01-01

    Large herbivores and carnivores (the megafauna) have been in a state of decline and extinction since the Late Pleistocene, both on land and more recently in the oceans. Much has been written on the timing and causes of these declines, but only recently has scientific attention focused on the consequences of these declines for ecosystem function. Here, we review progress in our understanding of how megafauna affect ecosystem physical and trophic structure, species composition, biogeochemistry, and climate, drawing on special features of PNAS and Ecography that have been published as a result of an international workshop on this topic held in Oxford in 2014. Insights emerging from this work have consequences for our understanding of changes in biosphere function since the Late Pleistocene and of the functioning of contemporary ecosystems, as well as offering a rationale and framework for scientifically informed restoration of megafaunal function where possible and appropriate. PMID:26811442

  3. Soil fauna, soil properties and geo-ecosystem functioning

    NASA Astrophysics Data System (ADS)

    Cammeraat, L. H.

    2012-04-01

    The impact of soil fauna on soil processes is of utmost importance, as the activity of soil fauna directly affects soil quality. This is expressed by the direct effects of soil fauna on soil physical and soil chemical properties that not only have great importance to food production and ecosystems services, but also on weathering and hydrological and geomorphological processes. Soil animals can be perceived as ecosystem engineers that directly affect the flow of water, sediments and nutrients through terrestrial ecosystems. The biodiversity of animals living in the soil is huge and shows a huge range in size, functions and effects. Most work has been focused on only a few species such as earthworms and termites, but in general the knowledge on the effect of soil biota on soil ecosystem functioning is limited as it is for their impact on processes in the soil and on the soil surface. In this presentation we would like to review some of the impacts of soil fauna on soil properties that have implications for geo-ecosystem functioning and soil formation processes.

  4. Mechanistic scaling of ecosystem function and dynamics in space and time: Ecosystem Demography model version 2

    NASA Astrophysics Data System (ADS)

    Medvigy, D.; Wofsy, S. C.; Munger, J. W.; Hollinger, D. Y.; Moorcroft, P. R.

    2009-03-01

    Insights into how terrestrial ecosystems affect the Earth's response to changes in climate and rising atmospheric CO2 levels rely heavily on the predictions of terrestrial biosphere models (TBMs). These models contain detailed mechanistic representations of biological processes affecting terrestrial ecosystems; however, their ability to simultaneously predict field-based measurements of terrestrial vegetation dynamics and carbon fluxes has remained largely untested. In this study, we address this issue by developing a constrained implementation of a new structured TBM, the Ecosystem Demography model version 2 (ED2), which explicitly tracks the dynamics of fine-scale ecosystem structure and function. Carbon and water flux measurements from an eddy-flux tower are used in conjunction with forest inventory measurements of tree growth and mortality at Harvard Forest (42.5°N, 72.1°W) to estimate a number of important but weakly constrained model parameters. Evaluation against a decade of tower flux and forest dynamics measurements shows that the constrained ED2 model yields greatly improved predictions of annual net ecosystem productivity, carbon partitioning, and growth and mortality dynamics of both hardwood and conifer trees. The generality of the model formulation is then evaluated by comparing the model's predictions against measurements from two other eddy-flux towers and forest inventories of the northeastern United States and Quebec. Despite the markedly different composition throughout this region, the optimized model realistically predicts observed patterns of carbon fluxes and tree growth. These results demonstrate how TBMs parameterized with field-based measurements can provide quantitative insight into the underlying biological processes governing ecosystem composition, structure, and function at larger scales.

  5. Maximum entropy models of ecosystem functioning

    NASA Astrophysics Data System (ADS)

    Bertram, Jason

    2014-12-01

    Using organism-level traits to deduce community-level relationships is a fundamental problem in theoretical ecology. This problem parallels the physical one of using particle properties to deduce macroscopic thermodynamic laws, which was successfully achieved with the development of statistical physics. Drawing on this parallel, theoretical ecologists from Lotka onwards have attempted to construct statistical mechanistic theories of ecosystem functioning. Jaynes' broader interpretation of statistical mechanics, which hinges on the entropy maximisation algorithm (MaxEnt), is of central importance here because the classical foundations of statistical physics do not have clear ecological analogues (e.g. phase space, dynamical invariants). However, models based on the information theoretic interpretation of MaxEnt are difficult to interpret ecologically. Here I give a broad discussion of statistical mechanical models of ecosystem functioning and the application of MaxEnt in these models. Emphasising the sample frequency interpretation of MaxEnt, I show that MaxEnt can be used to construct models of ecosystem functioning which are statistical mechanical in the traditional sense using a savanna plant ecology model as an example.

  6. Maximum entropy models of ecosystem functioning

    SciTech Connect

    Bertram, Jason

    2014-12-05

    Using organism-level traits to deduce community-level relationships is a fundamental problem in theoretical ecology. This problem parallels the physical one of using particle properties to deduce macroscopic thermodynamic laws, which was successfully achieved with the development of statistical physics. Drawing on this parallel, theoretical ecologists from Lotka onwards have attempted to construct statistical mechanistic theories of ecosystem functioning. Jaynes’ broader interpretation of statistical mechanics, which hinges on the entropy maximisation algorithm (MaxEnt), is of central importance here because the classical foundations of statistical physics do not have clear ecological analogues (e.g. phase space, dynamical invariants). However, models based on the information theoretic interpretation of MaxEnt are difficult to interpret ecologically. Here I give a broad discussion of statistical mechanical models of ecosystem functioning and the application of MaxEnt in these models. Emphasising the sample frequency interpretation of MaxEnt, I show that MaxEnt can be used to construct models of ecosystem functioning which are statistical mechanical in the traditional sense using a savanna plant ecology model as an example.

  7. Biodiversity and ecosystem functioning in dynamic landscapes.

    PubMed

    Brose, Ulrich; Hillebrand, Helmut

    2016-05-19

    The relationship between biodiversity and ecosystem functioning (BEF) and its consequence for ecosystem services has predominantly been studied by controlled, short-term and small-scale experiments under standardized environmental conditions and constant community compositions. However, changes in biodiversity occur in real-world ecosystems with varying environments and a dynamic community composition. In this theme issue, we present novel research on BEF in such dynamic communities. The contributions are organized in three sections on BEF relationships in (i) multi-trophic diversity, (ii) non-equilibrium biodiversity under disturbance and varying environmental conditions, and (iii) large spatial and long temporal scales. The first section shows that multi-trophic BEF relationships often appear idiosyncratic, while accounting for species traits enables a predictive understanding. Future BEF research on complex communities needs to include ecological theory that is based on first principles of species-averaged body masses, stoichiometry and effects of environmental conditions such as temperature. The second section illustrates that disturbance and varying environments have direct as well as indirect (via changes in species richness, community composition and species' traits) effects on BEF relationships. Fluctuations in biodiversity (species richness, community composition and also trait dominance within species) can severely modify BEF relationships. The third section demonstrates that BEF at larger spatial scales is driven by different variables. While species richness per se and community biomass are most important, species identity effects and community composition are less important than at small scales. Across long temporal scales, mass extinctions represent severe changes in biodiversity with mixed effects on ecosystem functions. Together, the contributions of this theme issue identify new research frontiers and answer some open questions on BEF relationships

  8. Biodiversity and ecosystem functioning in dynamic landscapes

    PubMed Central

    Brose, Ulrich; Hillebrand, Helmut

    2016-01-01

    The relationship between biodiversity and ecosystem functioning (BEF) and its consequence for ecosystem services has predominantly been studied by controlled, short-term and small-scale experiments under standardized environmental conditions and constant community compositions. However, changes in biodiversity occur in real-world ecosystems with varying environments and a dynamic community composition. In this theme issue, we present novel research on BEF in such dynamic communities. The contributions are organized in three sections on BEF relationships in (i) multi-trophic diversity, (ii) non-equilibrium biodiversity under disturbance and varying environmental conditions, and (iii) large spatial and long temporal scales. The first section shows that multi-trophic BEF relationships often appear idiosyncratic, while accounting for species traits enables a predictive understanding. Future BEF research on complex communities needs to include ecological theory that is based on first principles of species-averaged body masses, stoichiometry and effects of environmental conditions such as temperature. The second section illustrates that disturbance and varying environments have direct as well as indirect (via changes in species richness, community composition and species' traits) effects on BEF relationships. Fluctuations in biodiversity (species richness, community composition and also trait dominance within species) can severely modify BEF relationships. The third section demonstrates that BEF at larger spatial scales is driven by different variables. While species richness per se and community biomass are most important, species identity effects and community composition are less important than at small scales. Across long temporal scales, mass extinctions represent severe changes in biodiversity with mixed effects on ecosystem functions. Together, the contributions of this theme issue identify new research frontiers and answer some open questions on BEF relationships

  9. Loss of Rare Fish Species from Tropical Floodplain Food Webs Affects Community Structure and Ecosystem Multifunctionality in a Mesocosm Experiment

    PubMed Central

    Pendleton, Richard M.; Hoeinghaus, David J.; Gomes, Luiz C.; Agostinho, Angelo A.

    2014-01-01

    Experiments with realistic scenarios of species loss from multitrophic ecosystems may improve insight into how biodiversity affects ecosystem functioning. Using 1000 L mesocoms, we examined effects of nonrandom species loss on community structure and ecosystem functioning of experimental food webs based on multitrophic tropical floodplain lagoon ecosystems. Realistic biodiversity scenarios were developed based on long-term field surveys, and experimental assemblages replicated sequential loss of rare species which occurred across all trophic levels of these complex food webs. Response variables represented multiple components of ecosystem functioning, including nutrient cycling, primary and secondary production, organic matter accumulation and whole ecosystem metabolism. Species richness significantly affected ecosystem function, even after statistically controlling for potentially confounding factors such as total biomass and direct trophic interactions. Overall, loss of rare species was generally associated with lower nutrient concentrations, phytoplankton and zooplankton densities, and whole ecosystem metabolism when compared with more diverse assemblages. This pattern was also observed for overall ecosystem multifunctionality, a combined metric representing the ability of an ecosystem to simultaneously maintain multiple functions. One key exception was attributed to time-dependent effects of intraguild predation, which initially increased values for most ecosystem response variables, but resulted in decreases over time likely due to reduced nutrient remineralization by surviving predators. At the same time, loss of species did not result in strong trophic cascades, possibly a result of compensation and complexity of these multitrophic ecosystems along with a dominance of bottom-up effects. Our results indicate that although rare species may comprise minor components of communities, their loss can have profound ecosystem consequences across multiple trophic

  10. Loss of rare fish species from tropical floodplain food webs affects community structure and ecosystem multifunctionality in a mesocosm experiment.

    PubMed

    Pendleton, Richard M; Hoeinghaus, David J; Gomes, Luiz C; Agostinho, Angelo A

    2014-01-01

    Experiments with realistic scenarios of species loss from multitrophic ecosystems may improve insight into how biodiversity affects ecosystem functioning. Using 1000 L mesocoms, we examined effects of nonrandom species loss on community structure and ecosystem functioning of experimental food webs based on multitrophic tropical floodplain lagoon ecosystems. Realistic biodiversity scenarios were developed based on long-term field surveys, and experimental assemblages replicated sequential loss of rare species which occurred across all trophic levels of these complex food webs. Response variables represented multiple components of ecosystem functioning, including nutrient cycling, primary and secondary production, organic matter accumulation and whole ecosystem metabolism. Species richness significantly affected ecosystem function, even after statistically controlling for potentially confounding factors such as total biomass and direct trophic interactions. Overall, loss of rare species was generally associated with lower nutrient concentrations, phytoplankton and zooplankton densities, and whole ecosystem metabolism when compared with more diverse assemblages. This pattern was also observed for overall ecosystem multifunctionality, a combined metric representing the ability of an ecosystem to simultaneously maintain multiple functions. One key exception was attributed to time-dependent effects of intraguild predation, which initially increased values for most ecosystem response variables, but resulted in decreases over time likely due to reduced nutrient remineralization by surviving predators. At the same time, loss of species did not result in strong trophic cascades, possibly a result of compensation and complexity of these multitrophic ecosystems along with a dominance of bottom-up effects. Our results indicate that although rare species may comprise minor components of communities, their loss can have profound ecosystem consequences across multiple trophic

  11. Sperm function in affective illness.

    PubMed

    Amsterdam, J; Winokur, A; Levin, R

    1981-04-01

    There is evidence for functional changes in the hypothalamic-pituitary-gonadal axis of patients with affective disorders. Little is known concerning spermatogenesis or sperm function in depressed men. We systematically evaluated the sperm indices in a group of depressed males complaining of diminished libido, and a healthy control group. No differences were noted in sperm parameters between the groups.

  12. The intestinal ecosystem in chronic functional constipation.

    PubMed

    Zoppi, G; Cinquetti, M; Luciano, A; Benini, A; Muner, A; Bertazzoni Minelli, E

    1998-08-01

    Chronic functional constipation is common in infants, and the bacterial composition of stools in this condition is not known. The study aims were to: (i) investigate the composition of the intestinal ecosystem in chronic functional constipation; (ii) establish whether the addition of the water-holding agent calcium polycarbophil to the diet induces an improvement in constipation; and (iii) determine the composition of the intestinal ecosystem after the use of this agent. In total, 42 children (20F, 22M; mean age: 8.6 +/- 2.9 y) were studied. Twenty-eight children with functional chronic constipation without anatomical disorders were treated double-blind in random sequence for 1 month with an oral preparation of calcium polycarbophil (0.62 g/twice daily) or placebo. Intestinal flora composition was evaluated by standard microbiological methods and biochemical assays on faecal samples collected before and after treatment. Fourteen healthy children were studied as controls. The results show that (i) the constipated children presented a significant increase in clostridia and bifidobacteria in faeces compared to healthy subjects--different species of clostridia and enterobacteriaceae were frequently isolated; no generalized overgrowth was observed; Clostridia outnumbered bacteroides and E. coli mean counts by 2-3log, while bacteroides and E. coli counts were similar (5-6 log10/g fresh faeces); these intestinal disturbances could be defined as a dysbiosis, i.e. a quantitative alteration in the relative proportions of certain intestinal bacterial species. (ii) Clinical resolution of constipation was achieved only in 43% of treated children and an improvement in 21% (one bowel movement every 2 d). (iii) Calcium polycarbophil treatment induced no significant changes in the composition of the intestinal ecosystem, nor in blood chemistry parameters.

  13. Consumer diversity across kingdoms supports multiple functions in a coastal ecosystem.

    PubMed

    Hensel, Marc J S; Silliman, Brian R

    2013-12-17

    The global biodiversity crisis impairs the valuable benefits ecosystems provide humans. These nature-generated benefits are defined by a multitude of different ecosystem functions that operate simultaneously. Although several studies have simulated species loss in communities and tracked the response of single functions such as productivity or nutrient cycling, these studies have involved relatively similar taxa, and seldom are strikingly different functions examined. With the exception of highly managed ecosystems such as agricultural fields, rarely are we interested in only one function being performed well. Instead, we rely on ecosystems to deliver several different functions at the same time. Here, we experimentally investigated the extinction impacts of dominant consumers in a salt marsh. These consumers are remarkably phylogenetically diverse, spanning two kingdoms (i.e., Animalia and Fungi). Our field studies reveal that a diverse consumer assemblage significantly enhances simultaneous functioning of disparate ecosystem processes (i.e., productivity, decomposition, and infiltration). Extreme functional and phylogenetic differences among consumers underlie this relationship. Each marsh consumer affected at least one different ecosystem function, and each individual function was affected by no more than two consumers. The implications of these findings are profound: If we want ecosystems to perform many different functions well, it is not just number of species that matter. Rather, the presence of species representing markedly different ecologies and biology is also essential to maximizing multiple functions. Moreover, this work emphasizes the need to incorporate both microcomponents and macrocomponents of food webs to accurately predict biodiversity declines on integrated-ecosystem functioning.

  14. Consumer diversity across kingdoms supports multiple functions in a coastal ecosystem

    PubMed Central

    Hensel, Marc J. S.; Silliman, Brian R.

    2013-01-01

    The global biodiversity crisis impairs the valuable benefits ecosystems provide humans. These nature-generated benefits are defined by a multitude of different ecosystem functions that operate simultaneously. Although several studies have simulated species loss in communities and tracked the response of single functions such as productivity or nutrient cycling, these studies have involved relatively similar taxa, and seldom are strikingly different functions examined. With the exception of highly managed ecosystems such as agricultural fields, rarely are we interested in only one function being performed well. Instead, we rely on ecosystems to deliver several different functions at the same time. Here, we experimentally investigated the extinction impacts of dominant consumers in a salt marsh. These consumers are remarkably phylogenetically diverse, spanning two kingdoms (i.e., Animalia and Fungi). Our field studies reveal that a diverse consumer assemblage significantly enhances simultaneous functioning of disparate ecosystem processes (i.e., productivity, decomposition, and infiltration). Extreme functional and phylogenetic differences among consumers underlie this relationship. Each marsh consumer affected at least one different ecosystem function, and each individual function was affected by no more than two consumers. The implications of these findings are profound: If we want ecosystems to perform many different functions well, it is not just number of species that matter. Rather, the presence of species representing markedly different ecologies and biology is also essential to maximizing multiple functions. Moreover, this work emphasizes the need to incorporate both microcomponents and macrocomponents of food webs to accurately predict biodiversity declines on integrated-ecosystem functioning. PMID:24297926

  15. Marine biodiversity–ecosystem functions under uncertain environmental futures

    PubMed Central

    Bulling, Mark T.; Hicks, Natalie; Murray, Leigh; Paterson, David M.; Raffaelli, Dave; White, Piran C. L.; Solan, Martin

    2010-01-01

    Anthropogenic activity is currently leading to dramatic transformations of ecosystems and losses of biodiversity. The recognition that these ecosystems provide services that are essential for human well-being has led to a major interest in the forms of the biodiversity–ecosystem functioning relationship. However, there is a lack of studies examining the impact of climate change on these relationships and it remains unclear how multiple climatic drivers may affect levels of ecosystem functioning. Here, we examine the roles of two important climate change variables, temperature and concentration of atmospheric carbon dioxide, on the relationship between invertebrate species richness and nutrient release in a model benthic estuarine system. We found a positive relationship between invertebrate species richness and the levels of release of NH4-N into the water column, but no effect of species richness on the release of PO4-P. Higher temperatures and greater concentrations of atmospheric carbon dioxide had a negative impact on nutrient release. Importantly, we found significant interactions between the climate variables, indicating that reliably predicting the effects of future climate change will not be straightforward as multiple drivers are unlikely to have purely additive effects, resulting in increased levels of uncertainty. PMID:20513718

  16. Soil Nematode Diversity: Species Coexistence and Ecosystem Function

    PubMed Central

    Ettema, Christien H.

    1998-01-01

    Soil nematode species diversity is often high, both at ecosystem and single soil-core scales. First, how can so many species coexist? There is evidence of niche partitioning, notably of physical space, but vast interspecific overlaps and trait plasticity seem equally common. It appears that coexistence of species with similar resource needs is made possible by small-scale disturbance and predation, which likely reduce local population sizes and interspecific competition. Regional processes such as dispersal, large-scale disturbance, and aggregation, which govern ecosystem level diversity, may also affect local species interactions and soil-core scale diversity. Second, what is the significance of having so many species, with so few trophic functions, for ecosystem processes? Focusing on bacterivore diversity, it is clear that species contributions to decomposition, likely to differ as a function of individual biologies, are concealed by the trophic group approach. However, considerable functional redundancy probably exists, which may explain why decomposition processes are maintained in highly disturbed soils despite the extinction of many species. Thus, soil nematode diversity is important for the long-term stability of soil functioning, and merits protection and further study. PMID:19274206

  17. Multitrophic functional diversity predicts ecosystem functioning in experimental assemblages of estuarine consumers.

    PubMed

    Lefcheck, Jonathan S; Duffy, J Emmett

    2015-11-01

    The use of functional traits to explain how biodiversity affects ecosystem functioning has attracted intense interest, yet few studies have a priori altered functional diversity, especially in multitrophic communities. Here, we manipulated multivariate functional diversity of estuarine grazers and predators within multiple levels of species richness to test how species richness and functional diversity predicted ecosystem functioning in a multitrophic food web. Community functional diversity was a better predictor than species richness for the majority of ecosystem properties, based on generalized linear mixed-effects models. Combining inferences from eight traits into a single multivariate index increased prediction accuracy of these models relative to any individual trait. Structural equation modeling revealed that functional diversity of both grazers and predators was important in driving final biomass within trophic levels, with stronger effects observed for predators. We also show that different species drove different ecosystem responses, with evidence for both sampling effects and complementarity. Our study extends experimental investigations of functional trait diversity to a multilevel food web, and demonstrates that functional diversity can be more accurate and effective than species richness in predicting community biomass in a food web context. PMID:27070016

  18. Warming alters community size structure and ecosystem functioning.

    PubMed

    Dossena, Matteo; Yvon-Durocher, Gabriel; Grey, Jonathan; Montoya, José M; Perkins, Daniel M; Trimmer, Mark; Woodward, Guy

    2012-08-01

    Global warming can affect all levels of biological complexity, though we currently understand least about its potential impact on communities and ecosystems. At the ecosystem level, warming has the capacity to alter the structure of communities and the rates of key ecosystem processes they mediate. Here we assessed the effects of a 4°C rise in temperature on the size structure and taxonomic composition of benthic communities in aquatic mesocosms, and the rates of detrital decomposition they mediated. Warming had no effect on biodiversity, but altered community size structure in two ways. In spring, warmer systems exhibited steeper size spectra driven by declines in total community biomass and the proportion of large organisms. By contrast, in autumn, warmer systems had shallower size spectra driven by elevated total community biomass and a greater proportion of large organisms. Community-level shifts were mirrored by changes in decomposition rates. Temperature-corrected microbial and macrofaunal decomposition rates reflected the shifts in community structure and were strongly correlated with biomass across mesocosms. Our study demonstrates that the 4°C rise in temperature expected by the end of the century has the potential to alter the structure and functioning of aquatic ecosystems profoundly, as well as the intimate linkages between these levels of ecological organization.

  19. Warming alters community size structure and ecosystem functioning.

    PubMed

    Dossena, Matteo; Yvon-Durocher, Gabriel; Grey, Jonathan; Montoya, José M; Perkins, Daniel M; Trimmer, Mark; Woodward, Guy

    2012-08-01

    Global warming can affect all levels of biological complexity, though we currently understand least about its potential impact on communities and ecosystems. At the ecosystem level, warming has the capacity to alter the structure of communities and the rates of key ecosystem processes they mediate. Here we assessed the effects of a 4°C rise in temperature on the size structure and taxonomic composition of benthic communities in aquatic mesocosms, and the rates of detrital decomposition they mediated. Warming had no effect on biodiversity, but altered community size structure in two ways. In spring, warmer systems exhibited steeper size spectra driven by declines in total community biomass and the proportion of large organisms. By contrast, in autumn, warmer systems had shallower size spectra driven by elevated total community biomass and a greater proportion of large organisms. Community-level shifts were mirrored by changes in decomposition rates. Temperature-corrected microbial and macrofaunal decomposition rates reflected the shifts in community structure and were strongly correlated with biomass across mesocosms. Our study demonstrates that the 4°C rise in temperature expected by the end of the century has the potential to alter the structure and functioning of aquatic ecosystems profoundly, as well as the intimate linkages between these levels of ecological organization. PMID:22496185

  20. Community history affects the predictability of microbial ecosystem development

    PubMed Central

    Pagaling, Eulyn; Strathdee, Fiona; Spears, Bryan M; Cates, Michael E; Allen, Rosalind J; Free, Andrew

    2014-01-01

    Microbial communities mediate crucial biogeochemical, biomedical and biotechnological processes, yet our understanding of their assembly, and our ability to control its outcome, remain poor. Existing evidence presents conflicting views on whether microbial ecosystem assembly is predictable, or inherently unpredictable. We address this issue using a well-controlled laboratory model system, in which source microbial communities colonize a pristine environment to form complex, nutrient-cycling ecosystems. When the source communities colonize a novel environment, final community composition and function (as measured by redox potential) are unpredictable, although a signature of the community's previous history is maintained. However, when the source communities are pre-conditioned to their new habitat, community development is more reproducible. This situation contrasts with some studies of communities of macro-organisms, where strong selection under novel environmental conditions leads to reproducible community structure, whereas communities under weaker selection show more variability. Our results suggest that the microbial rare biosphere may have an important role in the predictability of microbial community development, and that pre-conditioning may help to reduce unpredictability in the design of microbial communities for biotechnological applications. PMID:23985743

  1. Realizing ecosystem services: wetland hydrologic function along a gradient of ecosystem condition.

    PubMed

    McLaughlin, Daniel L; Cohen, Matthew J

    2013-10-01

    Wetlands provide numerous ecosystem services, from habitat provision to pollutant removal, floodwater storage, and microclimate regulation. Delivery of particular services relies on specific ecological functions, and thus to varying degree on wetland ecological condition, commonly quantified as departure from minimally impacted reference sites. Condition assessments are widely adopted as regulatory indicators of ecosystem function, and for some services (e.g., habitat) links between condition and function are often direct. For others, however, links are more tenuous, and using condition alone to enumerate ecosystem value (e.g., for compensatory mitigation) may underestimate important services. Hydrologic function affects many services cited in support of wetland protection both directly (floodwater retention, microclimate regulation) and indirectly (biogeochemical cycling, pollutant removal). We investigated links between condition and hydrologic function to test the hypothesis, embedded in regulatory assessment of wetland value, that condition predicts function. Condition was assessed using rapid and intensive approaches, including Florida's official wetland assessment tool, in 11 isolated forested wetlands in north Florida (USA) spanning a land use intensity gradient. Hydrologic function was assessed using hydrologic regime (mean, variance, and rates of change of water depth), and measurements of groundwater exchange and evapotranspiration (ET). Despite a wide range in condition, no systematic variation in hydrologic regime was observed; indeed reference sites spanned the full range of variation. In contrast, ET was affected by land use, with higher rates in intensive (agriculture and urban) landscapes in response to higher leaf area. ET determines latent heat exchange, which regulates microclimate, a valuable service in urban heat islands. Higher ET also indicates higher productivity and thus carbon cycling. Groundwater exchange regularly reversed flow direction

  2. The Evolutionary Legacy of Diversification Predicts Ecosystem Function.

    PubMed

    Yguel, Benjamin; Jactel, Hervé; Pearse, Ian S; Moen, Daniel; Winter, Marten; Hortal, Joaquin; Helmus, Matthew R; Kühn, Ingolf; Pavoine, Sandrine; Purschke, Oliver; Weiher, Evan; Violle, Cyrille; Ozinga, Wim; Brändle, Martin; Bartish, Igor; Prinzing, Andreas

    2016-10-01

    Theory suggests that the structure of evolutionary history represented in a species community may affect its functioning, but phylogenetic diversity metrics do not allow for the identification of major differences in this structure. Here we propose a new metric, ELDERness (for Evolutionary Legacy of DivERsity) to estimate evolutionary branching patterns within communities by fitting a polynomial function to lineage-through-time (LTT) plots. We illustrate how real and simulated community branching patterns can be more correctly described by ELDERness and can successfully predict ecosystem functioning. In particular, the evolutionary history of branching patterns can be encapsulated by the parameters of third-order polynomial functions and further measured through only two parameters, the "ELDERness surfaces." These parameters captured variation in productivity of a grassland community better than existing phylogenetic diversity or diversification metrics and independent of species richness or presence of nitrogen fixers. Specifically, communities with small ELDERness surfaces (constant accumulation of lineages through time in LTT plots) were more productive, consistent with increased productivity resulting from complementary lineages combined with niche filling within lineages. Overall, while existing phylogenetic diversity metrics remain useful in many contexts, we suggest that our ELDERness approach better enables testing hypotheses that relate complex patterns of macroevolutionary history represented in local communities to ecosystem functioning.

  3. The Evolutionary Legacy of Diversification Predicts Ecosystem Function.

    PubMed

    Yguel, Benjamin; Jactel, Hervé; Pearse, Ian S; Moen, Daniel; Winter, Marten; Hortal, Joaquin; Helmus, Matthew R; Kühn, Ingolf; Pavoine, Sandrine; Purschke, Oliver; Weiher, Evan; Violle, Cyrille; Ozinga, Wim; Brändle, Martin; Bartish, Igor; Prinzing, Andreas

    2016-10-01

    Theory suggests that the structure of evolutionary history represented in a species community may affect its functioning, but phylogenetic diversity metrics do not allow for the identification of major differences in this structure. Here we propose a new metric, ELDERness (for Evolutionary Legacy of DivERsity) to estimate evolutionary branching patterns within communities by fitting a polynomial function to lineage-through-time (LTT) plots. We illustrate how real and simulated community branching patterns can be more correctly described by ELDERness and can successfully predict ecosystem functioning. In particular, the evolutionary history of branching patterns can be encapsulated by the parameters of third-order polynomial functions and further measured through only two parameters, the "ELDERness surfaces." These parameters captured variation in productivity of a grassland community better than existing phylogenetic diversity or diversification metrics and independent of species richness or presence of nitrogen fixers. Specifically, communities with small ELDERness surfaces (constant accumulation of lineages through time in LTT plots) were more productive, consistent with increased productivity resulting from complementary lineages combined with niche filling within lineages. Overall, while existing phylogenetic diversity metrics remain useful in many contexts, we suggest that our ELDERness approach better enables testing hypotheses that relate complex patterns of macroevolutionary history represented in local communities to ecosystem functioning. PMID:27622874

  4. Linking biodiversity to ecosystem function: Implications for conservation ecology

    USGS Publications Warehouse

    Schwartz, M.W.; Brigham, C.A.; Hoeksema, J.D.; Lyons, K.G.; Mills, M.H.; van Mantgem, P.

    2000-01-01

    We evaluate the empirical and theoretical support for the hypothesis that a large proportion of native species richness is required to maximize ecosystem stability and sustain function. This assessment is important for conservation strategies because sustenance of ecosystem functions has been used as an argument for the conservation of species. If ecosystem functions are sustained at relatively low species richness, then arguing for the conservation of ecosystem function, no matter how important in its own right, does not strongly argue for the conservation of species. Additionally, for this to be a strong conservation argument the link between species diversity and ecosystem functions of value to the human community must be clear. We review the empirical literature to quantify the support for two hypotheses: (1) species richness is positively correlated with ecosystem function, and (2) ecosystem functions do not saturate at low species richness relative to the observed or experimental diversity. Few empirical studies demonstrate improved function at high levels of species richness. Second, we analyze recent theoretical models in order to estimate the level of species richness required to maintain ecosystem function. Again we find that, within a single trophic level, most mathematical models predict saturation of ecosystem function at a low proportion of local species richness. We also analyze a theoretical model linking species number to ecosystem stability. This model predicts that species richness beyond the first few species does not typically increase ecosystem stability. One reason that high species richness may not contribute significantly to function or stability is that most communities are characterized by strong dominance such that a few species provide the vast majority of the community biomass. Rapid turnover of species may rescue the concept that diversity leads to maximum function and stability. The role of turnover in ecosystem function and

  5. Linking Ecosystem Services Benefit Transfer Databases and Ecosystem Services Production Function Libraries

    EPA Science Inventory

    The quantification or estimation of the economic and non-economic values of ecosystem services can be done from a number of distinct approaches. For example, practitioners may use ecosystem services production function models (ESPFMs) for a particular location, or alternatively, ...

  6. Plant functional traits predict green roof ecosystem services.

    PubMed

    Lundholm, Jeremy; Tran, Stephanie; Gebert, Luke

    2015-02-17

    Plants make important contributions to the services provided by engineered ecosystems such as green roofs. Ecologists use plant species traits as generic predictors of geographical distribution, interactions with other species, and ecosystem functioning, but this approach has been little used to optimize engineered ecosystems. Four plant species traits (height, individual leaf area, specific leaf area, and leaf dry matter content) were evaluated as predictors of ecosystem properties and services in a modular green roof system planted with 21 species. Six indicators of ecosystem services, incorporating thermal, hydrological, water quality, and carbon sequestration functions, were predicted by the four plant traits directly or indirectly via their effects on aggregate ecosystem properties, including canopy density and albedo. Species average height and specific leaf area were the most useful traits, predicting several services via effects on canopy density or growth rate. This study demonstrates that easily measured plant traits can be used to select species to optimize green roof performance across multiple key services.

  7. Plant functional traits predict green roof ecosystem services.

    PubMed

    Lundholm, Jeremy; Tran, Stephanie; Gebert, Luke

    2015-02-17

    Plants make important contributions to the services provided by engineered ecosystems such as green roofs. Ecologists use plant species traits as generic predictors of geographical distribution, interactions with other species, and ecosystem functioning, but this approach has been little used to optimize engineered ecosystems. Four plant species traits (height, individual leaf area, specific leaf area, and leaf dry matter content) were evaluated as predictors of ecosystem properties and services in a modular green roof system planted with 21 species. Six indicators of ecosystem services, incorporating thermal, hydrological, water quality, and carbon sequestration functions, were predicted by the four plant traits directly or indirectly via their effects on aggregate ecosystem properties, including canopy density and albedo. Species average height and specific leaf area were the most useful traits, predicting several services via effects on canopy density or growth rate. This study demonstrates that easily measured plant traits can be used to select species to optimize green roof performance across multiple key services. PMID:25599106

  8. Emergent global patterns of ecosystem structure and function from a mechanistic general ecosystem model.

    PubMed

    Harfoot, Michael B J; Newbold, Tim; Tittensor, Derek P; Emmott, Stephen; Hutton, Jon; Lyutsarev, Vassily; Smith, Matthew J; Scharlemann, Jörn P W; Purves, Drew W

    2014-04-01

    Anthropogenic activities are causing widespread degradation of ecosystems worldwide, threatening the ecosystem services upon which all human life depends. Improved understanding of this degradation is urgently needed to improve avoidance and mitigation measures. One tool to assist these efforts is predictive models of ecosystem structure and function that are mechanistic: based on fundamental ecological principles. Here we present the first mechanistic General Ecosystem Model (GEM) of ecosystem structure and function that is both global and applies in all terrestrial and marine environments. Functional forms and parameter values were derived from the theoretical and empirical literature where possible. Simulations of the fate of all organisms with body masses between 10 µg and 150,000 kg (a range of 14 orders of magnitude) across the globe led to emergent properties at individual (e.g., growth rate), community (e.g., biomass turnover rates), ecosystem (e.g., trophic pyramids), and macroecological scales (e.g., global patterns of trophic structure) that are in general agreement with current data and theory. These properties emerged from our encoding of the biology of, and interactions among, individual organisms without any direct constraints on the properties themselves. Our results indicate that ecologists have gathered sufficient information to begin to build realistic, global, and mechanistic models of ecosystems, capable of predicting a diverse range of ecosystem properties and their response to human pressures.

  9. Functional traits in agriculture: agrobiodiversity and ecosystem services.

    PubMed

    Wood, Stephen A; Karp, Daniel S; DeClerck, Fabrice; Kremen, Claire; Naeem, Shahid; Palm, Cheryl A

    2015-09-01

    Functional trait research has led to greater understanding of the impacts of biodiversity in ecosystems. Yet, functional trait approaches have not been widely applied to agroecosystems and understanding of the importance of agrobiodiversity remains limited to a few ecosystem processes and services. To improve this understanding, we argue here for a functional trait approach to agroecology that adopts recent advances in trait research for multitrophic and spatially heterogeneous ecosystems. We suggest that trait values should be measured across environmental conditions and agricultural management regimes to predict how ecosystem services vary with farm practices and environment. This knowledge should be used to develop management strategies that can be easily implemented by farmers to manage agriculture to provide multiple ecosystem services.

  10. A meta-analysis of zooplankton functional traits influencing ecosystem function.

    PubMed

    Hébert, Marie-Pier; Beisner, Beatrix E; Maranger, Roxane

    2016-04-01

    The use of functional traits to characterize community composition has been proposed as a more effective way to link community structure to ecosystem functioning. Organismal morphology, body stoichiometry, and physiology can be readily linked to large-scale ecosystem processes through functional traits that inform on interspecific and species-environment interactions; yet such effect traits are still poorly included in trait-based approaches. Given their key trophic position in aquatic ecosystems, individual zooplankton affect energy fluxes and elemental processing. We compiled a large database of zooplankton traits contributing to carbon, nitrogen, and phosphorus cycling and examined the effect of classification and habitat (marine vs. freshwater) on trait relationships. Respiration and nutrient excretion rates followed mass-dependent scaling in both habitats, with exponents ranging from 0.70 to 0.90. Our analyses revealed surprising differences in allometry and respiration between habitats, with freshwater species having lower length-specific mass and three times higher mass-specific respiration rates. These differences in traits point to implications for ecological strategies as well as overall carbon storage and fluxes based on habitat type. Our synthesis quantifies multiple trait relationships and links organisms to ecosystem processes they influence, enabling a more complete integration of aquatic community ecology and biogeochemistry through the promising use of effect traits. PMID:27220222

  11. A meta-analysis of zooplankton functional traits influencing ecosystem function.

    PubMed

    Hébert, Marie-Pier; Beisner, Beatrix E; Maranger, Roxane

    2016-04-01

    The use of functional traits to characterize community composition has been proposed as a more effective way to link community structure to ecosystem functioning. Organismal morphology, body stoichiometry, and physiology can be readily linked to large-scale ecosystem processes through functional traits that inform on interspecific and species-environment interactions; yet such effect traits are still poorly included in trait-based approaches. Given their key trophic position in aquatic ecosystems, individual zooplankton affect energy fluxes and elemental processing. We compiled a large database of zooplankton traits contributing to carbon, nitrogen, and phosphorus cycling and examined the effect of classification and habitat (marine vs. freshwater) on trait relationships. Respiration and nutrient excretion rates followed mass-dependent scaling in both habitats, with exponents ranging from 0.70 to 0.90. Our analyses revealed surprising differences in allometry and respiration between habitats, with freshwater species having lower length-specific mass and three times higher mass-specific respiration rates. These differences in traits point to implications for ecological strategies as well as overall carbon storage and fluxes based on habitat type. Our synthesis quantifies multiple trait relationships and links organisms to ecosystem processes they influence, enabling a more complete integration of aquatic community ecology and biogeochemistry through the promising use of effect traits.

  12. Functional structure of biological communities predicts ecosystem multifunctionality.

    PubMed

    Mouillot, David; Villéger, Sébastien; Scherer-Lorenzen, Michael; Mason, Norman W H

    2011-01-01

    The accelerating rate of change in biodiversity patterns, mediated by ever increasing human pressures and global warming, demands a better understanding of the relationship between the structure of biological communities and ecosystem functioning (BEF). Recent investigations suggest that the functional structure of communities, i.e. the composition and diversity of functional traits, is the main driver of ecological processes. However, the predictive power of BEF research is still low, the integration of all components of functional community structure as predictors is still lacking, and the multifunctionality of ecosystems (i.e. rates of multiple processes) must be considered. Here, using a multiple-processes framework from grassland biodiversity experiments, we show that functional identity of species and functional divergence among species, rather than species diversity per se, together promote the level of ecosystem multifunctionality with a predictive power of 80%. Our results suggest that primary productivity and decomposition rates, two key ecosystem processes upon which the global carbon cycle depends, are primarily sustained by specialist species, i.e. those that hold specialized combinations of traits and perform particular functions. Contrary to studies focusing on single ecosystem functions and considering species richness as the sole measure of biodiversity, we found a linear and non-saturating effect of the functional structure of communities on ecosystem multifunctionality. Thus, sustaining multiple ecological processes would require focusing on trait dominance and on the degree of community specialization, even in species-rich assemblages.

  13. Plant functional group composition modifies the effects of precipitation change on grassland ecosystem function.

    PubMed

    Fry, Ellen L; Manning, Pete; Allen, David G P; Hurst, Alex; Everwand, Georg; Rimmler, Martin; Power, Sally A

    2013-01-01

    Temperate grassland ecosystems face a future of precipitation change, which can alter community composition and ecosystem functions through reduced soil moisture and waterlogging. There is evidence that functionally diverse plant communities contain a wider range of water use and resource capture strategies, resulting in greater resistance of ecosystem function to precipitation change. To investigate this interaction between composition and precipitation change we performed a field experiment for three years in successional grassland in southern England. This consisted of two treatments. The first, precipitation change, simulated end of century predictions, and consisted of a summer drought phase alongside winter rainfall addition. The second, functional group identity, divided the plant community into three groups based on their functional traits- broadly described as perennials, caespitose grasses and annuals- and removed these groups in a factorial design. Ecosystem functions related to C, N and water cycling were measured regularly. Effects of functional groupidentity were apparent, with the dominant trend being that process rates were higher under control conditions where a range of perennial species were present. E.g. litter decomposition rates were significantly higher in plots containing several perennial species, the group with the highest average leaf N content. Process rates were also very strongly affected by the precipitation change treatmentwhen perennial plant species were dominant, but not where the community contained a high abundance of annual species and caespitose grasses. This contrasting response could be attributable to differing rooting patterns (shallower structures under annual plants, and deeper roots under perennials) and faster nutrient uptake in annuals compared to perennials. Our results indicate that precipitation change will have a smaller effect on key process rates in grasslandscontaining a range of perennial and annual species

  14. Delayed responses of an Arctic ecosystem to an extreme summer: impacts on net ecosystem exchange and vegetation functioning

    NASA Astrophysics Data System (ADS)

    Zona, D.; Lipson, D. A.; Richards, J. H.; Phoenix, G. K.; Liljedahl, A. K.; Ueyama, M.; Sturtevant, C. S.; Oechel, W. C.

    2014-10-01

    The importance and consequences of extreme events on the global carbon budget are inadequately understood. This includes the differential impact of extreme events on various ecosystem components, lag effects, recovery times, and compensatory processes. In the summer of 2007 in Barrow, Arctic Alaska, there were unusually high air temperatures (the fifth warmest summer over a 65-year period) and record low precipitation (the lowest over a 65-year period). These abnormal conditions were associated with substantial desiccation of the Sphagnum layer and a reduced net Sphagnum CO2 sink but did not affect net ecosystem exchange (NEE) from this wet-sedge arctic tundra ecosystem. Microbial biomass, NH4+ availability, gross primary production (GPP), and ecosystem respiration (Reco) were generally greater during this extreme summer. The cumulative ecosystem CO2 sink in 2007 was similar to the previous summers, suggesting that vascular plants were able to compensate for Sphagnum CO2 uptake, despite the impact on other functions and structure such as desiccation of the Sphagnum layer. Surprisingly, the lowest ecosystem CO2 sink over a five summer record (2005-2009) was observed during the 2008 summer (~70% lower), directly following the unusually warm and dry summer, rather than during the extreme summer. This sink reduction cannot solely be attributed to the potential damage to mosses, which typically contribute ~40% of the entire ecosystem CO2 sink. Importantly, the return to a substantial cumulative CO2 sink occurred two summers after the extreme event, which suggests a substantial resilience of this tundra ecosystem to at least an isolated extreme event. Overall, these results show a complex response of the CO2 sink and its sub-components to atypically warm and dry conditions. The impact of multiple extreme events requires further investigation.

  15. Asymmetric warming significantly affects net primary production, but not ecosystem carbon balances of forest and grassland ecosystems in northern China.

    PubMed

    Su, Hongxin; Feng, Jinchao; Axmacher, Jan C; Sang, Weiguo

    2015-01-01

    We combine the process-based ecosystem model (Biome-BGC) with climate change-scenarios based on both RegCM3 model outputs and historic observed trends to quantify differential effects of symmetric and asymmetric warming on ecosystem net primary productivity (NPP), heterotrophic respiration (Rh) and net ecosystem productivity (NEP) of six ecosystem types representing different climatic zones of northern China. Analysis of covariance shows that NPP is significant greater at most ecosystems under the various environmental change scenarios once temperature asymmetries are taken into consideration. However, these differences do not lead to significant differences in NEP, which indicates that asymmetry in climate change does not result in significant alterations of the overall carbon balance in the dominating forest or grassland ecosystems. Overall, NPP, Rh and NEP are regulated by highly interrelated effects of increases in temperature and atmospheric CO2 concentrations and precipitation changes, while the magnitude of these effects strongly varies across the six sites. Further studies underpinned by suitable experiments are nonetheless required to further improve the performance of ecosystem models and confirm the validity of these model predictions. This is crucial for a sound understanding of the mechanisms controlling the variability in asymmetric warming effects on ecosystem structure and functioning. PMID:25766381

  16. Asymmetric warming significantly affects net primary production, but not ecosystem carbon balances of forest and grassland ecosystems in northern China.

    PubMed

    Su, Hongxin; Feng, Jinchao; Axmacher, Jan C; Sang, Weiguo

    2015-03-13

    We combine the process-based ecosystem model (Biome-BGC) with climate change-scenarios based on both RegCM3 model outputs and historic observed trends to quantify differential effects of symmetric and asymmetric warming on ecosystem net primary productivity (NPP), heterotrophic respiration (Rh) and net ecosystem productivity (NEP) of six ecosystem types representing different climatic zones of northern China. Analysis of covariance shows that NPP is significant greater at most ecosystems under the various environmental change scenarios once temperature asymmetries are taken into consideration. However, these differences do not lead to significant differences in NEP, which indicates that asymmetry in climate change does not result in significant alterations of the overall carbon balance in the dominating forest or grassland ecosystems. Overall, NPP, Rh and NEP are regulated by highly interrelated effects of increases in temperature and atmospheric CO2 concentrations and precipitation changes, while the magnitude of these effects strongly varies across the six sites. Further studies underpinned by suitable experiments are nonetheless required to further improve the performance of ecosystem models and confirm the validity of these model predictions. This is crucial for a sound understanding of the mechanisms controlling the variability in asymmetric warming effects on ecosystem structure and functioning.

  17. Asymmetric warming significantly affects net primary production, but not ecosystem carbon balances of forest and grassland ecosystems in northern China

    NASA Astrophysics Data System (ADS)

    Su, Hongxin; Feng, Jinchao; Axmacher, Jan C.; Sang, Weiguo

    2015-03-01

    We combine the process-based ecosystem model (Biome-BGC) with climate change-scenarios based on both RegCM3 model outputs and historic observed trends to quantify differential effects of symmetric and asymmetric warming on ecosystem net primary productivity (NPP), heterotrophic respiration (Rh) and net ecosystem productivity (NEP) of six ecosystem types representing different climatic zones of northern China. Analysis of covariance shows that NPP is significant greater at most ecosystems under the various environmental change scenarios once temperature asymmetries are taken into consideration. However, these differences do not lead to significant differences in NEP, which indicates that asymmetry in climate change does not result in significant alterations of the overall carbon balance in the dominating forest or grassland ecosystems. Overall, NPP, Rh and NEP are regulated by highly interrelated effects of increases in temperature and atmospheric CO2 concentrations and precipitation changes, while the magnitude of these effects strongly varies across the six sites. Further studies underpinned by suitable experiments are nonetheless required to further improve the performance of ecosystem models and confirm the validity of these model predictions. This is crucial for a sound understanding of the mechanisms controlling the variability in asymmetric warming effects on ecosystem structure and functioning.

  18. Not all ski slopes are created equal: disturbance intensity affects ecosystem properties.

    PubMed

    Burt, Jennifer W; Rice, Kevin J

    2009-12-01

    In mountain regions around the world, downhill ski areas represent a significant source of anthropogenic disturbance while also providing recreation and revenue. Ski-run creation always results in some level of disturbance, but disturbance intensity varies greatly with construction method. Ski runs may be established either by clearing (cutting and removing tall vegetation) or by clearing and then machine-grading (leveling the soil surface with heavy equipment). To quantify how these different intensities of initial disturbance affect ecosystem properties, we extensively surveyed vegetation, soils, and environmental characteristics on cleared ski runs, graded ski runs, and adjacent reference forests across seven large downhill ski resorts in the northern Sierra Nevada, USA. We found that the greater disturbance intensity associated with grading resulted in greater impacts on all ecosystem properties considered, including plant community composition and diversity, soil characteristics relating to processes of nutrient cycling and retention, and measures of erosion potential. We also found that cleared ski runs retained many ecological similarities to reference forests and might even offer some added benefits by possessing greater plant species and functional diversity than either forests or graded runs. Because grading is more damaging to multiple indicators of ecosystem function, clearing rather than grading should be used to create ski slopes wherever practical.

  19. Species richness and biomass explain spatial turnover in ecosystem functioning across tropical and temperate ecosystems.

    PubMed

    Barnes, Andrew D; Weigelt, Patrick; Jochum, Malte; Ott, David; Hodapp, Dorothee; Haneda, Noor Farikhah; Brose, Ulrich

    2016-05-19

    Predicting ecosystem functioning at large spatial scales rests on our ability to scale up from local plots to landscapes, but this is highly contingent on our understanding of how functioning varies through space. Such an understanding has been hampered by a strong experimental focus of biodiversity-ecosystem functioning research restricted to small spatial scales. To address this limitation, we investigate the drivers of spatial variation in multitrophic energy flux-a measure of ecosystem functioning in complex communities-at the landscape scale. We use a structural equation modelling framework based on distance matrices to test how spatial and environmental distances drive variation in community energy flux via four mechanisms: species composition, species richness, niche complementarity and biomass. We found that in both a tropical and a temperate study region, geographical and environmental distance indirectly influence species richness and biomass, with clear evidence that these are the dominant mechanisms explaining variability in community energy flux over spatial and environmental gradients. Our results reveal that species composition and trait variability may become redundant in predicting ecosystem functioning at the landscape scale. Instead, we demonstrate that species richness and total biomass may best predict rates of ecosystem functioning at larger spatial scales. PMID:27114580

  20. Species richness and biomass explain spatial turnover in ecosystem functioning across tropical and temperate ecosystems.

    PubMed

    Barnes, Andrew D; Weigelt, Patrick; Jochum, Malte; Ott, David; Hodapp, Dorothee; Haneda, Noor Farikhah; Brose, Ulrich

    2016-05-19

    Predicting ecosystem functioning at large spatial scales rests on our ability to scale up from local plots to landscapes, but this is highly contingent on our understanding of how functioning varies through space. Such an understanding has been hampered by a strong experimental focus of biodiversity-ecosystem functioning research restricted to small spatial scales. To address this limitation, we investigate the drivers of spatial variation in multitrophic energy flux-a measure of ecosystem functioning in complex communities-at the landscape scale. We use a structural equation modelling framework based on distance matrices to test how spatial and environmental distances drive variation in community energy flux via four mechanisms: species composition, species richness, niche complementarity and biomass. We found that in both a tropical and a temperate study region, geographical and environmental distance indirectly influence species richness and biomass, with clear evidence that these are the dominant mechanisms explaining variability in community energy flux over spatial and environmental gradients. Our results reveal that species composition and trait variability may become redundant in predicting ecosystem functioning at the landscape scale. Instead, we demonstrate that species richness and total biomass may best predict rates of ecosystem functioning at larger spatial scales.

  1. Rare species support vulnerable functions in high-diversity ecosystems.

    PubMed

    Mouillot, David; Bellwood, David R; Baraloto, Christopher; Chave, Jerome; Galzin, Rene; Harmelin-Vivien, Mireille; Kulbicki, Michel; Lavergne, Sebastien; Lavorel, Sandra; Mouquet, Nicolas; Paine, C E Timothy; Renaud, Julien; Thuiller, Wilfried

    2013-01-01

    Around the world, the human-induced collapses of populations and species have triggered a sixth mass extinction crisis, with rare species often being the first to disappear. Although the role of species diversity in the maintenance of ecosystem processes has been widely investigated, the role of rare species remains controversial. A critical issue is whether common species insure against the loss of functions supported by rare species. This issue is even more critical in species-rich ecosystems where high functional redundancy among species is likely and where it is thus often assumed that ecosystem functioning is buffered against species loss. Here, using extensive datasets of species occurrences and functional traits from three highly diverse ecosystems (846 coral reef fishes, 2,979 alpine plants, and 662 tropical trees), we demonstrate that the most distinct combinations of traits are supported predominantly by rare species both in terms of local abundance and regional occupancy. Moreover, species that have low functional redundancy and are likely to support the most vulnerable functions, with no other species carrying similar combinations of traits, are rarer than expected by chance in all three ecosystems. For instance, 63% and 98% of fish species that are likely to support highly vulnerable functions in coral reef ecosystems are locally and regionally rare, respectively. For alpine plants, 32% and 89% of such species are locally and regionally rare, respectively. Remarkably, 47% of fish species and 55% of tropical tree species that are likely to support highly vulnerable functions have only one individual per sample on average. Our results emphasize the importance of rare species conservation, even in highly diverse ecosystems, which are thought to exhibit high functional redundancy. Rare species offer more than aesthetic, cultural, or taxonomic diversity value; they disproportionately increase the potential breadth of functions provided by ecosystems across

  2. Rare Species Support Vulnerable Functions in High-Diversity Ecosystems

    PubMed Central

    Mouillot, David; Bellwood, David R.; Baraloto, Christopher; Chave, Jerome; Galzin, Rene; Harmelin-Vivien, Mireille; Kulbicki, Michel; Lavergne, Sebastien; Lavorel, Sandra; Mouquet, Nicolas; Paine, C. E. Timothy; Renaud, Julien; Thuiller, Wilfried

    2013-01-01

    Around the world, the human-induced collapses of populations and species have triggered a sixth mass extinction crisis, with rare species often being the first to disappear. Although the role of species diversity in the maintenance of ecosystem processes has been widely investigated, the role of rare species remains controversial. A critical issue is whether common species insure against the loss of functions supported by rare species. This issue is even more critical in species-rich ecosystems where high functional redundancy among species is likely and where it is thus often assumed that ecosystem functioning is buffered against species loss. Here, using extensive datasets of species occurrences and functional traits from three highly diverse ecosystems (846 coral reef fishes, 2,979 alpine plants, and 662 tropical trees), we demonstrate that the most distinct combinations of traits are supported predominantly by rare species both in terms of local abundance and regional occupancy. Moreover, species that have low functional redundancy and are likely to support the most vulnerable functions, with no other species carrying similar combinations of traits, are rarer than expected by chance in all three ecosystems. For instance, 63% and 98% of fish species that are likely to support highly vulnerable functions in coral reef ecosystems are locally and regionally rare, respectively. For alpine plants, 32% and 89% of such species are locally and regionally rare, respectively. Remarkably, 47% of fish species and 55% of tropical tree species that are likely to support highly vulnerable functions have only one individual per sample on average. Our results emphasize the importance of rare species conservation, even in highly diverse ecosystems, which are thought to exhibit high functional redundancy. Rare species offer more than aesthetic, cultural, or taxonomic diversity value; they disproportionately increase the potential breadth of functions provided by ecosystems across

  3. Maintaining ecosystem function and services in logged tropical forests.

    PubMed

    Edwards, David P; Tobias, Joseph A; Sheil, Douglas; Meijaard, Erik; Laurance, William F

    2014-09-01

    Vast expanses of tropical forests worldwide are being impacted by selective logging. We evaluate the environmental impacts of such logging and conclude that natural timber-production forests typically retain most of their biodiversity and associated ecosystem functions, as well as their carbon, climatic, and soil-hydrological ecosystem services. Unfortunately, the value of production forests is often overlooked, leaving them vulnerable to further degradation including post-logging clearing, fires, and hunting. Because logged tropical forests are extensive, functionally diverse, and provide many ecosystem services, efforts to expand their role in conservation strategies are urgently needed. Key priorities include improving harvest practices to reduce negative impacts on ecosystem functions and services, and preventing the rapid conversion and loss of logged forests. PMID:25092495

  4. Linking stoichiometric homoeostasis with ecosystem structure, functioning and stability.

    PubMed

    Yu, Qiang; Chen, Quansheng; Elser, James J; He, Nianpeng; Wu, Honghui; Zhang, Guangming; Wu, Jianguo; Bai, Yongfei; Han, Xingguo

    2010-11-01

    Ecosystem structure, functioning and stability have been a focus of ecological and environmental sciences during the past two decades. The mechanisms underlying their relationship, however, are not well understood. Based on comprehensive studies in Inner Mongolia grassland, here we show that species-level stoichiometric homoeostasis was consistently positively correlated with dominance and stability on both 2-year and 27-year temporal scales and across a 1200-km spatial transect. At the community level, stoichiometric homoeostasis was also positively correlated with ecosystem function and stability in most cases. Thus, homoeostatic species tend to have high and stable biomass; and ecosystems dominated by more homoeostatic species have higher productivity and greater stability. By modulating organism responses to key environmental drivers, stoichiometric homoeostasis appears to be a major mechanism responsible for the structure, functioning and stability of grassland ecosystems.

  5. Maintaining ecosystem function and services in logged tropical forests.

    PubMed

    Edwards, David P; Tobias, Joseph A; Sheil, Douglas; Meijaard, Erik; Laurance, William F

    2014-09-01

    Vast expanses of tropical forests worldwide are being impacted by selective logging. We evaluate the environmental impacts of such logging and conclude that natural timber-production forests typically retain most of their biodiversity and associated ecosystem functions, as well as their carbon, climatic, and soil-hydrological ecosystem services. Unfortunately, the value of production forests is often overlooked, leaving them vulnerable to further degradation including post-logging clearing, fires, and hunting. Because logged tropical forests are extensive, functionally diverse, and provide many ecosystem services, efforts to expand their role in conservation strategies are urgently needed. Key priorities include improving harvest practices to reduce negative impacts on ecosystem functions and services, and preventing the rapid conversion and loss of logged forests.

  6. Ecosystem Functions Connecting Contributions from Ecosystem Services to Human Wellbeing in a Mangrove System in Northern Taiwan.

    PubMed

    Hsieh, Hwey-Lian; Lin, Hsing-Juh; Shih, Shang-Shu; Chen, Chang-Po

    2015-06-09

    The present study examined a mangrove ecosystem in northern Taiwan to determine how the various components of ecosystem function, ecosystem services and human wellbeing are connected. The overall contributions of mangrove services to specific components of human wellbeing were also assessed. A network was developed and evaluated by an expert panel consisting of hydrologists, ecologists, and experts in the field of culture, landscape or architecture. The results showed that supporting habitats was the most important function to human wellbeing, while water quality, habitable climate, air quality, recreational opportunities, and knowledge systems were services that were strongly linked to human welfare. Security of continuous supply of services appeared to be the key to a comfortable life. From a bottom-up and top-down perspective, knowledge systems (a service) were most supported by ecosystem functions, while the security of continuous supply of services (wellbeing) had affected the most services. In addition, the overall benefits of mangrove services to human prosperity concentrated on mental health, security of continuous supply of services, and physical health.

  7. Ecosystem Functions Connecting Contributions from Ecosystem Services to Human Wellbeing in a Mangrove System in Northern Taiwan.

    PubMed

    Hsieh, Hwey-Lian; Lin, Hsing-Juh; Shih, Shang-Shu; Chen, Chang-Po

    2015-06-01

    The present study examined a mangrove ecosystem in northern Taiwan to determine how the various components of ecosystem function, ecosystem services and human wellbeing are connected. The overall contributions of mangrove services to specific components of human wellbeing were also assessed. A network was developed and evaluated by an expert panel consisting of hydrologists, ecologists, and experts in the field of culture, landscape or architecture. The results showed that supporting habitats was the most important function to human wellbeing, while water quality, habitable climate, air quality, recreational opportunities, and knowledge systems were services that were strongly linked to human welfare. Security of continuous supply of services appeared to be the key to a comfortable life. From a bottom-up and top-down perspective, knowledge systems (a service) were most supported by ecosystem functions, while the security of continuous supply of services (wellbeing) had affected the most services. In addition, the overall benefits of mangrove services to human prosperity concentrated on mental health, security of continuous supply of services, and physical health. PMID:26067989

  8. Ecosystem Functions Connecting Contributions from Ecosystem Services to Human Wellbeing in a Mangrove System in Northern Taiwan

    PubMed Central

    Hsieh, Hwey-Lian; Lin, Hsing-Juh; Shih, Shang-Shu; Chen, Chang-Po

    2015-01-01

    The present study examined a mangrove ecosystem in northern Taiwan to determine how the various components of ecosystem function, ecosystem services and human wellbeing are connected. The overall contributions of mangrove services to specific components of human wellbeing were also assessed. A network was developed and evaluated by an expert panel consisting of hydrologists, ecologists, and experts in the field of culture, landscape or architecture. The results showed that supporting habitats was the most important function to human wellbeing, while water quality, habitable climate, air quality, recreational opportunities, and knowledge systems were services that were strongly linked to human welfare. Security of continuous supply of services appeared to be the key to a comfortable life. From a bottom-up and top-down perspective, knowledge systems (a service) were most supported by ecosystem functions, while the security of continuous supply of services (wellbeing) had affected the most services. In addition, the overall benefits of mangrove services to human prosperity concentrated on mental health, security of continuous supply of services, and physical health. PMID:26067989

  9. Irrigation agriculture affects organic matter decomposition in semi-arid terrestrial and aquatic ecosystems.

    PubMed

    Arroita, Maite; Causapé, Jesús; Comín, Francisco A; Díez, Joserra; Jimenez, Juan José; Lacarta, Juan; Lorente, Carmen; Merchán, Daniel; Muñiz, Selene; Navarro, Enrique; Val, Jonatan; Elosegi, Arturo

    2013-12-15

    Many dryland areas are being converted into intensively managed irrigation crops, what can disrupt the hydrological regime, degrade soil and water quality, enhance siltation, erosion and bank instability, and affect biological communities. Still, the impacts of irrigation schemes on the functioning of terrestrial and aquatic ecosystems are poorly understood. Here we assess the effects of irrigation agriculture on breakdown of coarse organic matter in soil and water. We measured breakdown rates of alder and holm oak leaves, and of poplar sticks in terrestrial and aquatic sites following a gradient of increasing irrigation agriculture in a semi-arid Mediterranean basin transformed into irrigation agriculture in 50% of its surface. Spatial patterns of stick breakdown paralleled those of leaf breakdown. In soil, stick breakdown rates were extremely low in non-irrigated sites (0.0001-0.0003 day(-1)), and increased with the intensity of agriculture (0.0018-0.0044 day(-1)). In water, stick breakdown rates ranged from 0.0005 to 0.001 day(-1), and increased with the area of the basin subject to irrigation agriculture. Results showed that irrigation agriculture affects functioning of both terrestrial and aquatic ecosystems, accelerating decomposition of organic matter, especially in soil. These changes can have important consequences for global carbon budgets.

  10. Irrigation agriculture affects organic matter decomposition in semi-arid terrestrial and aquatic ecosystems.

    PubMed

    Arroita, Maite; Causapé, Jesús; Comín, Francisco A; Díez, Joserra; Jimenez, Juan José; Lacarta, Juan; Lorente, Carmen; Merchán, Daniel; Muñiz, Selene; Navarro, Enrique; Val, Jonatan; Elosegi, Arturo

    2013-12-15

    Many dryland areas are being converted into intensively managed irrigation crops, what can disrupt the hydrological regime, degrade soil and water quality, enhance siltation, erosion and bank instability, and affect biological communities. Still, the impacts of irrigation schemes on the functioning of terrestrial and aquatic ecosystems are poorly understood. Here we assess the effects of irrigation agriculture on breakdown of coarse organic matter in soil and water. We measured breakdown rates of alder and holm oak leaves, and of poplar sticks in terrestrial and aquatic sites following a gradient of increasing irrigation agriculture in a semi-arid Mediterranean basin transformed into irrigation agriculture in 50% of its surface. Spatial patterns of stick breakdown paralleled those of leaf breakdown. In soil, stick breakdown rates were extremely low in non-irrigated sites (0.0001-0.0003 day(-1)), and increased with the intensity of agriculture (0.0018-0.0044 day(-1)). In water, stick breakdown rates ranged from 0.0005 to 0.001 day(-1), and increased with the area of the basin subject to irrigation agriculture. Results showed that irrigation agriculture affects functioning of both terrestrial and aquatic ecosystems, accelerating decomposition of organic matter, especially in soil. These changes can have important consequences for global carbon budgets. PMID:23891536

  11. Quantitative criteria for estimation of natural and artificial ecosystems functioning.

    PubMed

    Pechurkin, N S

    2005-01-01

    Using biotic turnover of substances in trophic chains, natural and artificial ecosystems are similar in functioning, but different in structure. It is necessary to have quantitative criteria to evaluate the efficiency of artificial ecosystems (AES). These criteria are dependent on the specific objectives for which the AES are designed. For example, if AES is considered for use in space, important criteria are efficiency in use of mass, power, volume (size) and human labor and reliability. Another task involves the determination of quantitative criteria for the functioning of natural ecosystems. To solve the problem, it is fruitful to use a hierarchical approach suitable for both individual links and the ecosystem as a whole. Energy flux criteria (principles) were developed to estimate the functional activities of biosystems at the population, community and ecosystem levels. A major feature of ecosystems as a whole is their biotic turnover of matter the rate of which is restricted by the lack of limiting substances. Obviously, the most generalized criterion is to take into account the energy flux used by the biosystem and the quantity of limiting substance included in its turnover. The use of energy flux by ecosystem, E(USED)--is determined from the photoassimilation of CO2 by plants (per time unit). It can be approximately estimated as the net primary production of photosynthesis (NPP). So, the ratio of CO2 photoassimilation rate (sometimes, measured as NPP) to the total mass of limiting substrate can serve as a main universal criterion (MUC). This MUC characterizes the specific cycling rate of limiting chemical elements in the system and effectiveness of every ecosystem including the global Biosphere. Comparative analysis and elaboration of quantitative criteria for estimation of natural and artificial ecosystems activities is of high importance both for theoretical considerations and for real applications.

  12. Structural and functional loss in restored wetland ecosystems.

    PubMed

    Moreno-Mateos, David; Power, Mary E; Comín, Francisco A; Yockteng, Roxana

    2012-01-01

    Wetlands are among the most productive and economically valuable ecosystems in the world. However, because of human activities, over half of the wetland ecosystems existing in North America, Europe, Australia, and China in the early 20th century have been lost. Ecological restoration to recover critical ecosystem services has been widely attempted, but the degree of actual recovery of ecosystem functioning and structure from these efforts remains uncertain. Our results from a meta-analysis of 621 wetland sites from throughout the world show that even a century after restoration efforts, biological structure (driven mostly by plant assemblages), and biogeochemical functioning (driven primarily by the storage of carbon in wetland soils), remained on average 26% and 23% lower, respectively, than in reference sites. Either recovery has been very slow, or postdisturbance systems have moved towards alternative states that differ from reference conditions. We also found significant effects of environmental settings on the rate and degree of recovery. Large wetland areas (>100 ha) and wetlands restored in warm (temperate and tropical) climates recovered more rapidly than smaller wetlands and wetlands restored in cold climates. Also, wetlands experiencing more (riverine and tidal) hydrologic exchange recovered more rapidly than depressional wetlands. Restoration performance is limited: current restoration practice fails to recover original levels of wetland ecosystem functions, even after many decades. If restoration as currently practiced is used to justify further degradation, global loss of wetland ecosystem function and structure will spread.

  13. Structural and Functional Loss in Restored Wetland Ecosystems

    PubMed Central

    Moreno-Mateos, David; Power, Mary E.; Comín, Francisco A.; Yockteng, Roxana

    2012-01-01

    Wetlands are among the most productive and economically valuable ecosystems in the world. However, because of human activities, over half of the wetland ecosystems existing in North America, Europe, Australia, and China in the early 20th century have been lost. Ecological restoration to recover critical ecosystem services has been widely attempted, but the degree of actual recovery of ecosystem functioning and structure from these efforts remains uncertain. Our results from a meta-analysis of 621 wetland sites from throughout the world show that even a century after restoration efforts, biological structure (driven mostly by plant assemblages), and biogeochemical functioning (driven primarily by the storage of carbon in wetland soils), remained on average 26% and 23% lower, respectively, than in reference sites. Either recovery has been very slow, or postdisturbance systems have moved towards alternative states that differ from reference conditions. We also found significant effects of environmental settings on the rate and degree of recovery. Large wetland areas (>100 ha) and wetlands restored in warm (temperate and tropical) climates recovered more rapidly than smaller wetlands and wetlands restored in cold climates. Also, wetlands experiencing more (riverine and tidal) hydrologic exchange recovered more rapidly than depressional wetlands. Restoration performance is limited: current restoration practice fails to recover original levels of wetland ecosystem functions, even after many decades. If restoration as currently practiced is used to justify further degradation, global loss of wetland ecosystem function and structure will spread. PMID:22291572

  14. Structural and functional loss in restored wetland ecosystems.

    PubMed

    Moreno-Mateos, David; Power, Mary E; Comín, Francisco A; Yockteng, Roxana

    2012-01-01

    Wetlands are among the most productive and economically valuable ecosystems in the world. However, because of human activities, over half of the wetland ecosystems existing in North America, Europe, Australia, and China in the early 20th century have been lost. Ecological restoration to recover critical ecosystem services has been widely attempted, but the degree of actual recovery of ecosystem functioning and structure from these efforts remains uncertain. Our results from a meta-analysis of 621 wetland sites from throughout the world show that even a century after restoration efforts, biological structure (driven mostly by plant assemblages), and biogeochemical functioning (driven primarily by the storage of carbon in wetland soils), remained on average 26% and 23% lower, respectively, than in reference sites. Either recovery has been very slow, or postdisturbance systems have moved towards alternative states that differ from reference conditions. We also found significant effects of environmental settings on the rate and degree of recovery. Large wetland areas (>100 ha) and wetlands restored in warm (temperate and tropical) climates recovered more rapidly than smaller wetlands and wetlands restored in cold climates. Also, wetlands experiencing more (riverine and tidal) hydrologic exchange recovered more rapidly than depressional wetlands. Restoration performance is limited: current restoration practice fails to recover original levels of wetland ecosystem functions, even after many decades. If restoration as currently practiced is used to justify further degradation, global loss of wetland ecosystem function and structure will spread. PMID:22291572

  15. The effects of food web structure on ecosystem function exceeds those of precipitation.

    PubMed

    Trzcinski, M Kurtis; Srivastava, Diane S; Corbara, Bruno; Dézerald, Olivier; Leroy, Céline; Carrias, Jean-François; Dejean, Alain; Céréghino, Régis

    2016-09-01

    Ecosystems are being stressed by climate change, but few studies have tested food web responses to changes in precipitation patterns and the consequences to ecosystem function. Fewer still have considered whether results from one geographic region can be applied to other regions, given the degree of community change over large biogeographic gradients. We assembled, in one field site, three types of macroinvertebrate communities within water-filled bromeliads. Two represented food webs containing both a fast filter feeder-microbial and slow detritivore energy channels found in Costa Rica and Puerto Rico, and one represented the structurally simpler food webs in French Guiana, which only contained the fast filter feeder-microbial channel. We manipulated the amount and distribution of rain entering bromeliads and examined how food web structure mediated ecosystem responses to changes in the quantity and temporal distribution of precipitation. Food web structure affected the survival of functional groups in general and ecosystem functions such as decomposition and the production of fine particulate organic matter. Ecosystem processes were more affected by decreased precipitation than were the abundance of micro-organisms and metazoans. In our experiments, the sensitivity of the ecosystem to precipitation change was primarily revealed in the food web dominated by the single filter feeder-microbial channel because other top-down and bottom-up processes were weak or absent. Our results show stronger effects of food web structure than precipitation change per se on the functioning of bromeliad ecosystems. Consequently, we predict that ecosystem function in bromeliads throughout the Americas will be more sensitive to changes in the distribution of species, rather than to the direct effects caused by changes in precipitation. PMID:27120013

  16. The effects of food web structure on ecosystem function exceeds those of precipitation.

    PubMed

    Trzcinski, M Kurtis; Srivastava, Diane S; Corbara, Bruno; Dézerald, Olivier; Leroy, Céline; Carrias, Jean-François; Dejean, Alain; Céréghino, Régis

    2016-09-01

    Ecosystems are being stressed by climate change, but few studies have tested food web responses to changes in precipitation patterns and the consequences to ecosystem function. Fewer still have considered whether results from one geographic region can be applied to other regions, given the degree of community change over large biogeographic gradients. We assembled, in one field site, three types of macroinvertebrate communities within water-filled bromeliads. Two represented food webs containing both a fast filter feeder-microbial and slow detritivore energy channels found in Costa Rica and Puerto Rico, and one represented the structurally simpler food webs in French Guiana, which only contained the fast filter feeder-microbial channel. We manipulated the amount and distribution of rain entering bromeliads and examined how food web structure mediated ecosystem responses to changes in the quantity and temporal distribution of precipitation. Food web structure affected the survival of functional groups in general and ecosystem functions such as decomposition and the production of fine particulate organic matter. Ecosystem processes were more affected by decreased precipitation than were the abundance of micro-organisms and metazoans. In our experiments, the sensitivity of the ecosystem to precipitation change was primarily revealed in the food web dominated by the single filter feeder-microbial channel because other top-down and bottom-up processes were weak or absent. Our results show stronger effects of food web structure than precipitation change per se on the functioning of bromeliad ecosystems. Consequently, we predict that ecosystem function in bromeliads throughout the Americas will be more sensitive to changes in the distribution of species, rather than to the direct effects caused by changes in precipitation.

  17. Toxins in transgenic crop byproducts may affect headwater stream ecosystems.

    PubMed

    Rosi-Marshall, E J; Tank, J L; Royer, T V; Whiles, M R; Evans-White, M; Chambers, C; Griffiths, N A; Pokelsek, J; Stephen, M L

    2007-10-01

    Corn (Zea mays L.) that has been genetically engineered to produce the Cry1Ab protein (Bt corn) is resistant to lepidopteran pests. Bt corn is widely planted in the midwestern United States, often adjacent to headwater streams. We show that corn byproducts, such as pollen and detritus, enter headwater streams and are subject to storage, consumption, and transport to downstream water bodies. Laboratory feeding trials showed that consumption of Bt corn byproducts reduced growth and increased mortality of nontarget stream insects. Stream insects are important prey for aquatic and riparian predators, and widespread planting of Bt crops has unexpected ecosystem-scale consequences. PMID:17923672

  18. Declining resilience of ecosystem functions under biodiversity loss.

    PubMed

    Oliver, Tom H; Isaac, Nick J B; August, Tom A; Woodcock, Ben A; Roy, David B; Bullock, James M

    2015-12-08

    The composition of species communities is changing rapidly through drivers such as habitat loss and climate change, with potentially serious consequences for the resilience of ecosystem functions on which humans depend. To assess such changes in resilience, we analyse trends in the frequency of species in Great Britain that provide key ecosystem functions--specifically decomposition, carbon sequestration, pollination, pest control and cultural values. For 4,424 species over four decades, there have been significant net declines among animal species that provide pollination, pest control and cultural values. Groups providing decomposition and carbon sequestration remain relatively stable, as fewer species are in decline and these are offset by large numbers of new arrivals into Great Britain. While there is general concern about degradation of a wide range of ecosystem functions, our results suggest actions should focus on particular functions for which there is evidence of substantial erosion of their resilience.

  19. How stock of origin affects performance of individuals across a meta-ecosystem: an example from sockeye salmon.

    PubMed

    Griffiths, Jennifer R; Schindler, Daniel E; Seeb, Lisa W

    2013-01-01

    Connectivity among diverse habitats can buffer populations from adverse environmental conditions, influence the functioning of meta-ecosystems, and ultimately affect the reliability of ecosystem services. This stabilizing effect on populations is proposed to derive from complementarity in growth and survival conditions experienced by individuals in the different habitats that comprise meta-ecosystems. Here we use the fine scale differentiation of salmon populations between diverse lake habitats to assess how rearing habitat and stock of origin affect the body condition of juvenile sockeye salmon. We use genetic markers (single nucleotide polymorphisms) to assign individuals of unknown origin to stock group and in turn characterize ecologically relevant attributes across habitats and stocks. Our analyses show that the body condition of juvenile salmon is related to the productivity of alternative habitats across the watershed, irrespective of their stock of origin. Emigrants and residents with genetic origins in the high productivity lake were also differentiated by their body condition, poor and high respectively. These emigrants represented a substantial proportion of juvenile sockeye salmon rearing in the lower productivity lake habitat. Despite emigrants originating from the more productive lake, they did not differ in body condition from the individuals spawned in the lower productivity, recipient habitat. Genetic tools allowed us to assess the performance of different stocks groups across the diverse habitats comprising their meta-ecosystem. The ability to characterize the ecological consequences of meta-ecosystem connectivity can help develop strategies to protect and restore ecosystems and the services they provide to humans. PMID:23505539

  20. How Stock of Origin Affects Performance of Individuals across a Meta-Ecosystem: An Example from Sockeye Salmon

    PubMed Central

    Griffiths, Jennifer R.; Schindler, Daniel E.; Seeb, Lisa W.

    2013-01-01

    Connectivity among diverse habitats can buffer populations from adverse environmental conditions, influence the functioning of meta-ecosystems, and ultimately affect the reliability of ecosystem services. This stabilizing effect on populations is proposed to derive from complementarity in growth and survival conditions experienced by individuals in the different habitats that comprise meta-ecosystems. Here we use the fine scale differentiation of salmon populations between diverse lake habitats to assess how rearing habitat and stock of origin affect the body condition of juvenile sockeye salmon. We use genetic markers (single nucleotide polymorphisms) to assign individuals of unknown origin to stock group and in turn characterize ecologically relevant attributes across habitats and stocks. Our analyses show that the body condition of juvenile salmon is related to the productivity of alternative habitats across the watershed, irrespective of their stock of origin. Emigrants and residents with genetic origins in the high productivity lake were also differentiated by their body condition, poor and high respectively. These emigrants represented a substantial proportion of juvenile sockeye salmon rearing in the lower productivity lake habitat. Despite emigrants originating from the more productive lake, they did not differ in body condition from the individuals spawned in the lower productivity, recipient habitat. Genetic tools allowed us to assess the performance of different stocks groups across the diverse habitats comprising their meta-ecosystem. The ability to characterize the ecological consequences of meta-ecosystem connectivity can help develop strategies to protect and restore ecosystems and the services they provide to humans. PMID:23505539

  1. Placebo Sleep Affects Cognitive Functioning

    ERIC Educational Resources Information Center

    Draganich, Christina; Erdal, Kristi

    2014-01-01

    The placebo effect is any outcome that is not attributed to a specific treatment but rather to an individual's mindset (Benson & Friedman, 1996). This phenomenon can extend beyond its typical use in pharmaceutical drugs to involve aspects of everyday life, such as the effect of sleep on cognitive functioning. In 2 studies examining whether…

  2. Detecting Subtle Shifts in Ecosystem Functioning in a Dynamic Estuarine Environment.

    PubMed

    Pratt, Daniel R; Lohrer, Andrew M; Thrush, Simon F; Hewitt, Judi E; Townsend, Michael; Cartner, Katie; Pilditch, Conrad A; Harris, Rachel J; van Colen, Carl; Rodil, Iván F

    2015-01-01

    Identifying the effects of stressors before they impact ecosystem functioning can be challenging in dynamic, heterogeneous 'real-world' ecosystems. In aquatic systems, for example, reductions in water clarity can limit the light available for photosynthesis, with knock-on consequences for secondary consumers, though in naturally turbid wave-swept estuaries, detecting the effects of elevated turbidity can be difficult. The objective of this study was to investigate the effects of shading on ecosystem functions mediated by sandflat primary producers (microphytobenthos) and deep-dwelling surface-feeding macrofauna (Macomona liliana; Bivalvia, Veneroida, Tellinidae). Shade cloths (which reduced incident light intensity by ~80%) were deployed on an exposed, intertidal sandflat to experimentally stress the microphytobenthic community associated with the sediment surface. After 13 weeks, sediment properties, macrofauna and fluxes of oxygen and inorganic nutrients across the sediment-water interface were measured. A multivariate metric of ecosystem function (MF) was generated by combining flux-based response variables, and distance-based linear models were used to determine shifts in the drivers of ecosystem function between non-shaded and shaded plots. No significant differences in MF or in the constituent ecosystem function variables were detected between the shaded and non-shaded plots. However, shading reduced the total explained variation in MF (from 64% in non-shaded plots to 15% in shaded plots) and affected the relative influence of M. liliana and other explanatory variables on MF. This suggests that although shade stress may shift the drivers of ecosystem functioning (consistent with earlier investigations of shading effects on sandflat interaction networks), ecosystem functions appear to have a degree of resilience to those changes.

  3. Detecting Subtle Shifts in Ecosystem Functioning in a Dynamic Estuarine Environment

    PubMed Central

    Pratt, Daniel R.; Lohrer, Andrew M.; Thrush, Simon F.; Hewitt, Judi E.; Townsend, Michael; Cartner, Katie; Pilditch, Conrad A.; Harris, Rachel J.; van Colen, Carl; Rodil, Iván F.

    2015-01-01

    Identifying the effects of stressors before they impact ecosystem functioning can be challenging in dynamic, heterogeneous ‘real-world’ ecosystems. In aquatic systems, for example, reductions in water clarity can limit the light available for photosynthesis, with knock-on consequences for secondary consumers, though in naturally turbid wave-swept estuaries, detecting the effects of elevated turbidity can be difficult. The objective of this study was to investigate the effects of shading on ecosystem functions mediated by sandflat primary producers (microphytobenthos) and deep-dwelling surface-feeding macrofauna (Macomona liliana; Bivalvia, Veneroida, Tellinidae). Shade cloths (which reduced incident light intensity by ~80%) were deployed on an exposed, intertidal sandflat to experimentally stress the microphytobenthic community associated with the sediment surface. After 13 weeks, sediment properties, macrofauna and fluxes of oxygen and inorganic nutrients across the sediment-water interface were measured. A multivariate metric of ecosystem function (MF) was generated by combining flux-based response variables, and distance-based linear models were used to determine shifts in the drivers of ecosystem function between non-shaded and shaded plots. No significant differences in MF or in the constituent ecosystem function variables were detected between the shaded and non-shaded plots. However, shading reduced the total explained variation in MF (from 64% in non-shaded plots to 15% in shaded plots) and affected the relative influence of M. liliana and other explanatory variables on MF. This suggests that although shade stress may shift the drivers of ecosystem functioning (consistent with earlier investigations of shading effects on sandflat interaction networks), ecosystem functions appear to have a degree of resilience to those changes. PMID:26214854

  4. Detecting Subtle Shifts in Ecosystem Functioning in a Dynamic Estuarine Environment.

    PubMed

    Pratt, Daniel R; Lohrer, Andrew M; Thrush, Simon F; Hewitt, Judi E; Townsend, Michael; Cartner, Katie; Pilditch, Conrad A; Harris, Rachel J; van Colen, Carl; Rodil, Iván F

    2015-01-01

    Identifying the effects of stressors before they impact ecosystem functioning can be challenging in dynamic, heterogeneous 'real-world' ecosystems. In aquatic systems, for example, reductions in water clarity can limit the light available for photosynthesis, with knock-on consequences for secondary consumers, though in naturally turbid wave-swept estuaries, detecting the effects of elevated turbidity can be difficult. The objective of this study was to investigate the effects of shading on ecosystem functions mediated by sandflat primary producers (microphytobenthos) and deep-dwelling surface-feeding macrofauna (Macomona liliana; Bivalvia, Veneroida, Tellinidae). Shade cloths (which reduced incident light intensity by ~80%) were deployed on an exposed, intertidal sandflat to experimentally stress the microphytobenthic community associated with the sediment surface. After 13 weeks, sediment properties, macrofauna and fluxes of oxygen and inorganic nutrients across the sediment-water interface were measured. A multivariate metric of ecosystem function (MF) was generated by combining flux-based response variables, and distance-based linear models were used to determine shifts in the drivers of ecosystem function between non-shaded and shaded plots. No significant differences in MF or in the constituent ecosystem function variables were detected between the shaded and non-shaded plots. However, shading reduced the total explained variation in MF (from 64% in non-shaded plots to 15% in shaded plots) and affected the relative influence of M. liliana and other explanatory variables on MF. This suggests that although shade stress may shift the drivers of ecosystem functioning (consistent with earlier investigations of shading effects on sandflat interaction networks), ecosystem functions appear to have a degree of resilience to those changes. PMID:26214854

  5. Contrasting tropical estuarine ecosystem functioning and stability: A comparative study

    NASA Astrophysics Data System (ADS)

    Villanueva, Maria Ching

    2015-03-01

    A comparative study of the Sine-saloum (Senegal) and Gambia (The Gambia) estuaries was performed based on trophic model outputs that describe the system structure and functioning. These trophic models were constructed such as to differentiate main energetic flows in the systems and express how climate change may have impacted ecosystem resilience to change. Estuarine fish assemblages are highly resilient despite exposure to vast hydrodynamic variations and stress. Coupled with strong anthropogenic-driven stresses such as fisheries and climate change, ecosystems may undergo severe regime shifts that may weaken their resilience and stability. Taxonomically related and morphologically similar species do not necessarily play similar ecological roles in these two ecosystems. Biomass and production in the Sine-saloum are concentrated at trophic levels (TLs) 2 and 3, while for the Gambia, both are concentrated at TL3. Higher TL biomasses in Gambia compared to Sine-Saloum may be explained by the latter ecosystem being characterized by inverse hypersalinity. Higher TL of production in Sine-Saloum is due to higher exploitations compared to Gambia where fishing activities are still less developed. High production and consumption rates of some groups in both ecosystems indicate high system productivity. Elevated productivity may be due to higher abundance of juvenile fishes in most groups that utilize the latter as refuge and/or nursery zones. Both ecosystems are phytoplankton-driven. Differences in group trophic and ecological roles are mainly due to adaptive responses of these species to seasonal and long-term climate and anthropogenic stressors. System indicators suggest different levels of ecosystem resilience and stability as a function of biodiversity. Relevance of other observations on ecosystem functioning and indicators in relation to perturbation is discussed.

  6. Consumer diversity interacts with prey defenses to drive ecosystem function

    PubMed Central

    Rasher, Douglas B.; Hoey, Andrew S.; Hay, Mark E.

    2013-01-01

    Prey traits linking consumer diversity to ecosystem function remain poorly understood. On tropical coral reefs, herbivores promote coral dominance by suppressing competing macroalgae, but the roles of herbivore identity and diversity, macroalgal defenses, and their interactions in affecting reef resilience and function are unclear. We studied adjacent pairs of no-take marine reserves and fished areas on reefs in Fiji, and found that protected reefs supported 7–17x greater biomass and 2–3x higher species richness of herbivorous fishes, and 3–11x more live coral cover than did fished reefs. In contrast, macroalgae were 27–61x more abundant and 3–4x more species rich on fished reefs. When we transplanted seven common macroalgae from fished reefs into reserves they were rapidly consumed, suggesting that rates of herbivory (ecosystem functioning) differed inside versus outside reserves. We then video recorded feeding activity on the same seven macroalgae when transplanted into reserves, and assessed the functional redundancy versus complementarity of herbivorous fishes consuming these macroalgae. Of 29 species of larger herbivorous fishes on these reefs, only four species accounted for 97% of macroalgal consumption. Two unicornfish consumed a range of brown macroalgae, a parrotfish consumed multiple red algae, and a rabbitfish consumed a green alga, with almost no diet overlap among these groups. The two most chemically rich, allelopathic algae were each consumed by a single, but different, fish species. This striking complementarity resulted from herbivore species differing in their tolerances to macroalgal chemical and structural defenses. A model of assemblage diet breadth based on our feeding observations predicted that high browser diversity would be required for effective control of macroalgae on Fijian reefs. In support of this model, we observed strong, negative relationships between herbivore diversity and macroalgal abundance and diversity across the

  7. Consumer diversity interacts with prey defenses to drive ecosystem function.

    PubMed

    Rasher, Douglas B; Hoey, Andrew S; Hay, Mark E

    2013-06-01

    Prey traits linking consumer diversity to ecosystem function remain poorly understood. On tropical coral reefs, herbivores promote coral dominance by suppressing competing macroalgae, but the roles of herbivore identity and diversity, macroalgal defenses, and their interactions in affecting reef resilience and function are unclear. We studied adjacent pairs of no-take marine reserves and fished areas on reefs in Fiji and found that protected reefs supported 7-17x greater biomass, 2-3x higher species richness of herbivorous fishes, and 3-11x more live coral cover than did fished reefs. In contrast, macroalgae were 27-61x more abundant and 3-4x more species-rich on fished reefs. When we transplanted seven common macroalgae from fished reefs into reserves they were rapidly consumed, suggesting that rates of herbivory (ecosystem functioning) differed inside vs. outside reserves. We then video-recorded feeding activity on the same seven macroalgae when transplanted into reserves, and assessed the functional redundancy vs. complementarity of herbivorous fishes consuming these macroalgae. Of 29 species of larger herbivorous fishes on these reefs, only four species accounted for 97% of macroalgal consumption. Two unicornfish consumed a range of brown macroalgae, a parrotfish consumed multiple red algae, and a rabbitfish consumed a green alga, with almost no diet overlap among these groups. The two most chemically rich, allelopathic algae were each consumed by a single, but different, fish species. This striking complementarity resulted from herbivore species differing in their tolerances to macroalgal chemical and structural defenses. A model of assemblage diet breadth based on our feeding observations predicted that high browser diversity would be required for effective control of macroalgae on Fijian reefs. In support of this model, we observed strong negative relationships between herbivore diversity and macroalgal abundance and diversity across the six study reefs. Our

  8. Plant hydraulics as a hub integrating plant and ecosystem function

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Water plays a central role in plant biology and the efficiency of water transport throughout the plant (i.e., “plant hydraulics”) affects both photosynthetic rate and growth, an influence that scales up deterministically to the productivity of terrestrial ecosystems. Moreover, hydraulic traits media...

  9. Declining resilience of ecosystem functions under biodiversity loss

    PubMed Central

    Oliver, Tom H.; Isaac, Nick J. B.; August, Tom A.; Woodcock, Ben A.; Roy, David B.; Bullock, James M.

    2015-01-01

    The composition of species communities is changing rapidly through drivers such as habitat loss and climate change, with potentially serious consequences for the resilience of ecosystem functions on which humans depend. To assess such changes in resilience, we analyse trends in the frequency of species in Great Britain that provide key ecosystem functions—specifically decomposition, carbon sequestration, pollination, pest control and cultural values. For 4,424 species over four decades, there have been significant net declines among animal species that provide pollination, pest control and cultural values. Groups providing decomposition and carbon sequestration remain relatively stable, as fewer species are in decline and these are offset by large numbers of new arrivals into Great Britain. While there is general concern about degradation of a wide range of ecosystem functions, our results suggest actions should focus on particular functions for which there is evidence of substantial erosion of their resilience. PMID:26646209

  10. Global biodiversity, stoichiometry and ecosystem function responses to human-induced C-N-P imbalances.

    PubMed

    Carnicer, Jofre; Sardans, Jordi; Stefanescu, Constantí; Ubach, Andreu; Bartrons, Mireia; Asensio, Dolores; Peñuelas, Josep

    2015-01-01

    Global change analyses usually consider biodiversity as a global asset that needs to be preserved. Biodiversity is frequently analysed mainly as a response variable affected by diverse environmental drivers. However, recent studies highlight that gradients of biodiversity are associated with gradual changes in the distribution of key dominant functional groups characterized by distinctive traits and stoichiometry, which in turn often define the rates of ecosystem processes and nutrient cycling. Moreover, pervasive links have been reported between biodiversity, food web structure, ecosystem function and species stoichiometry. Here we review current global stoichiometric gradients and how future distributional shifts in key functional groups may in turn influence basic ecosystem functions (production, nutrient cycling, decomposition) and therefore could exert a feedback effect on stoichiometric gradients. The C-N-P stoichiometry of most primary producers (phytoplankton, algae, plants) has been linked to functional trait continua (i.e. to major axes of phenotypic variation observed in inter-specific analyses of multiple traits). In contrast, the C-N-P stoichiometry of higher-level consumers remains less precisely quantified in many taxonomic groups. We show that significant links are observed between trait continua across trophic levels. In spite of recent advances, the future reciprocal feedbacks between key functional groups, biodiversity and ecosystem functions remain largely uncertain. The reported evidence, however, highlights the key role of stoichiometric traits and suggests the need of a progressive shift towards an ecosystemic and stoichiometric perspective in global biodiversity analyses. PMID:25270104

  11. Global biodiversity, stoichiometry and ecosystem function responses to human-induced C-N-P imbalances.

    PubMed

    Carnicer, Jofre; Sardans, Jordi; Stefanescu, Constantí; Ubach, Andreu; Bartrons, Mireia; Asensio, Dolores; Peñuelas, Josep

    2015-01-01

    Global change analyses usually consider biodiversity as a global asset that needs to be preserved. Biodiversity is frequently analysed mainly as a response variable affected by diverse environmental drivers. However, recent studies highlight that gradients of biodiversity are associated with gradual changes in the distribution of key dominant functional groups characterized by distinctive traits and stoichiometry, which in turn often define the rates of ecosystem processes and nutrient cycling. Moreover, pervasive links have been reported between biodiversity, food web structure, ecosystem function and species stoichiometry. Here we review current global stoichiometric gradients and how future distributional shifts in key functional groups may in turn influence basic ecosystem functions (production, nutrient cycling, decomposition) and therefore could exert a feedback effect on stoichiometric gradients. The C-N-P stoichiometry of most primary producers (phytoplankton, algae, plants) has been linked to functional trait continua (i.e. to major axes of phenotypic variation observed in inter-specific analyses of multiple traits). In contrast, the C-N-P stoichiometry of higher-level consumers remains less precisely quantified in many taxonomic groups. We show that significant links are observed between trait continua across trophic levels. In spite of recent advances, the future reciprocal feedbacks between key functional groups, biodiversity and ecosystem functions remain largely uncertain. The reported evidence, however, highlights the key role of stoichiometric traits and suggests the need of a progressive shift towards an ecosystemic and stoichiometric perspective in global biodiversity analyses.

  12. Ecosystem functioning impacts of the invasive seaweed Sargassum muticum (Fucales, Phaeophyceae).

    PubMed

    Vaz-Pinto, Fátima; Olabarria, Celia; Arenas, Francisco

    2014-02-01

    Ongoing changes in natural diversity due to anthropogenic activities can alter ecosystem functioning. Particular attention has been given to research on biodiversity loss and how those changes can affect the functioning of ecosystems, and, by extension, human welfare. Few studies, however, have addressed how increased diversity due to establishment of nonindigenous species (NIS) may affect ecosystem function in the recipient communities. Marine algae have a highly important role in sustaining nearshore marine ecosystems and are considered a significant component of marine bioinvasions. Here, we examined the patterns of respiration and light-use efficiency across macroalgal assemblages with different levels of species richness and evenness. Additionally, we compared our results between native and invaded macroalgal assemblages, using the invasive brown macroalga Sargassum muticum (Yendo) Fensholt as a model species. Results showed that the presence of the invader increased the rates of respiration and production, most likely as a result of the high biomass of the invader. This effect disappeared when S. muticum lost most of its biomass after senescence. Moreover, predictability-diversity relationships of macroalgal assemblages varied between native and invaded assemblages. Hence, the introduction of high-impact invasive species may trigger major changes in ecosystem functioning. The impact of S. muticum may be related to its greater biomass in the invaded assemblages, although species interactions and seasonality influenced the magnitude of the impact. PMID:26988012

  13. Biodiversity, community structure and function of biofilms in stream ecosystems.

    PubMed

    Besemer, Katharina

    2015-12-01

    Multi-species, surface-attached biofilms often dominate microbial life in streams and rivers, where they contribute substantially to biogeochemical processes. The microbial diversity of natural biofilms is huge, and may have important implications for the functioning of aquatic environments and the ecosystem services they provide. Yet the causes and consequences of biofilm biodiversity remain insufficiently understood. This review aims to give an overview of current knowledge on the distribution of stream biofilm biodiversity, the mechanisms generating biodiversity patterns and the relationship between biofilm biodiversity and ecosystem functioning.

  14. Linking community size structure and ecosystem functioning using metabolic theory

    PubMed Central

    Yvon-Durocher, Gabriel; Allen, Andrew P.

    2012-01-01

    Understanding how biogeochemical cycles relate to the structure of ecological communities is a central research question in ecology. Here we approach this problem by focusing on body size, which is an easily measured species trait that has a pervasive influence on multiple aspects of community structure and ecosystem functioning. We test the predictions of a model derived from metabolic theory using data on ecosystem metabolism and community size structure. These data were collected as part of an aquatic mesocosm experiment that was designed to simulate future environmental warming. Our analyses demonstrate significant linkages between community size structure and ecosystem functioning, and the effects of warming on these links. Specifically, we show that carbon fluxes were significantly influenced by seasonal variation in temperature, and yielded activation energies remarkably similar to those predicted based on the temperature dependencies of individual-level photosynthesis and respiration. We also show that community size structure significantly influenced fluxes of ecosystem respiration and gross primary production, particularly at the annual time-scale. Assessing size structure and the factors that control it, both empirically and theoretically, therefore promises to aid in understanding links between individual organisms and biogeochemical cycles, and in predicting the responses of key ecosystem functions to future environmental change. PMID:23007088

  15. From Elements to Metabolism: Linking Organismal Stoichiometry to Ecosystem Function

    NASA Astrophysics Data System (ADS)

    Cohen, M. J.; Nifong, R. L.

    2014-12-01

    Metabolism is an integrative metric of ecosystem function and energetics, synthesizing the relative contributions of multiple inputs, processes, and interactions. Stoichiometry is a framework based on elemental ratios for understanding how organisms interact within ecosystems. Linking the two has the potential to yield fresh insight about how ecosystems utilize elements and energy. We sought to quantify the link between the stoichiometry of ecosystem metabolism, specifically the C:N:P ratios of integrated autotrophic assimilation, and the stoichiometric tissue ratios observed in the dominant autotrophs. Using high frequency in situ nutrient sensors we estimated the assimilatory fluxes of C, N, and P in multiple spring-fed rivers of varying autotrophic species composition. We measured autotroph cover in each spring river, collected composite vegetation samples, and evaluated tissue stoichiometry; as expected, we observed large differences in C:N and N:P between algal and vascular plant taxa. We observed associations between measured tissue stoichiometry and elemental ratios at the ecosystem scale, suggesting that aggregated assimilatory fluxes may be useful for partitioning primary production and linking organismal nutrient content to the stoichiometry of ecosystem metabolism.

  16. Does microbial biomass affect pelagic ecosystem efficiency? An experimental study.

    PubMed

    Wehr, J D; Le, J; Campbell, L

    1994-01-01

    Bacteria and other microorganisms in the pelagic zone participate in the recycling of organic matter and nutrients within the water column. The microbial loop is thought to enhance ecosystem efficiency through rapid recycling and reduced sinking rates, thus reducing the loss of nutrients contained in organisms remaining within the photic zone. We conducted experiments with lake communities in 5400-liter mesocosms, and measured the flux of materials and nutrients out of the water column. A factorial design manipulated 8 nutrient treatments: 4 phosphorus levels × 2 nitrogen levels. Total sedimentation rates were greatest in high-N mesocosms; within N-surplus communities, [Symbol: see text]1 µM P resulted in 50% increase in total particulate losses. P additions without added N had small effects on nutrient losses from the photic zone; +2 µM P tanks received 334 mg P per tank, yet after 14 days lost only 69 mg more particulate-P than did control communities. Nutrient treatments resulted in marked differences in phytoplankton biomass (twofold N effect, fivefold P effect in +N mesocosms only), bacterioplankton densities (twofold N-effect, twofold P effects in -N and +N mesocosms), and the relative importance of autotrophic picoplankton (maximum in high NY mesocosms). Multiple regression analysis found that of 8 plankton and water chemistry variables, the ratio of autotrophic picoplankton to total phytoplankton (measured as chlorophyll α) explained the largest portion of the total variation in sedimentation loss rates (65% of P-flux, 57% of N-flux, 26% of total flux). In each case, systems with greater relative importance of autotrophic picoplankton had significantly reduced loss rates. In contrast, greater numbers of planktonic bacteria were associated with increased sedimentation rates and lower system efficiency. We suggest that different microbial components may have contrasting effects on the presumed enhanced efficiency provided by the microbial loop.

  17. Does shallow geothermal energy use threaten groundwater ecosystem functions?

    NASA Astrophysics Data System (ADS)

    Brielmann, Heike; Schmidt, Susanne I.; Ferraro, Francesco; Schreglmann, Kathrin; Griebler, Christian; Lueders, Tillmann

    2010-05-01

    Today, the use of geothermal energy is strongly promoted as an alternative and sustainable source of energy. However, regarding the authorization, regulation and monitoring of such facilities with respect to possible environmental impacts, a severe lack of knowledge has been identified. Aquifers are not only abiotic reservoirs of water and sediment, but they are complex ecosystems harbouring an almost untapped diversity of microorganisms and fauna. Intrinsic groundwater organisms are highly adapted to extremely oligotrophic, but stable conditions including temperature. At the same time, groundwater biota are the key drivers of important ecosystem services, especially functions connected to water quality. So what happens if groundwater biota need to cope with sudden temperature dynamics caused by GSHP use? Potential effects of thermal use on pristine aquifers, and on groundwater systems already facing enhanced loads of nutrients or contamination require urgent scientific attention. Within this project, we have assessed - both in the field and in the laboratory - the impacts of temperature discharge and withdrawal on biotic parameters and functional characteristics of exemplary shallow groundwater systems. In the field, aquifer microbes did not show significant impacts under increased temperatures in terms of total cell numbers, selected enzyme activities and carbon production. However, bacterial diversity clearly increased with temperature, accompanied by the appearance of new bacterial lineages and the disappearance of others. On the contrary, faunal diversity decreased with temperature, highlighting the temperature sensitivity of groundwater invertebrates. These results demonstrate that aquifer thermal energy discharge can affect intrinsic aquifer biotic populations, while at the same time being only one of several drivers contributing to total variability connected to seasonal dynamics and spatial heterogeneity. In laboratory column experiments covering a larger

  18. Rapidly restoring biological soil crusts and ecosystem functions in a severely disturbed desert ecosystem.

    PubMed

    Chiquoine, Lindsay P; Abella, Scott R; Bowker, Matthew A

    2016-06-01

    Restoring biological soil crusts (biocrusts) in degraded drylands can contribute to recovery of ecosystem functions that have global implications, including erosion resistance and nutrient cycling. To examine techniques for restoring biocrusts, we conducted a replicated, factorial experiment on recently abandoned road surfaces by applying biocrust inoculation (salvaged and stored dry for two years), salvaged topsoil, an abiotic soil amendment (wood shavings), and planting of a dominant perennial shrub (Ambrosia dumosa). Eighteen months after treatments, we measured biocrust abundance and species composition, soil chlorophyll a content and fertility, and soil resistance to erosion. Biocrust addition significantly accelerated biocrust recovery on disturbed soils, including increasing lichen and moss cover and cyanobacteria colonization. Compared to undisturbed controls, inoculated plots had similar lichen and moss composition, recovered 43% of total cyanobacteria density, had similar soil chlorophyll content, and exhibited recovery of soil fertility and soil stability. Inoculation was the only treatment that generated lichen and moss cover. Topsoil application resulted in partial recovery of the cyanobacteria community and soil properties. Compared to untreated disturbed plots, topsoil application without inoculum increased cyanobacteria density by 186% and moderately improved soil chlorophyll and ammonium content and soil stability. Topsoil application produced 22% and 51% of the cyanobacteria density g⁻¹ soil compared to undisturbed and inoculated plots, respectively. Plots not treated with either topsoil or inoculum had significantly lower cyanobacteria density, soil chlorophyll and ammonium concentrations, and significantly higher soil nitrate concentration. Wood shavings and Ambrosia had no influence on biocrust lichen and moss species recovery but did affect cyanobacteria composition and soil fertility. Inoculation of severely disturbed soil with native

  19. Rapidly restoring biological soil crusts and ecosystem functions in a severely disturbed desert ecosystem.

    PubMed

    Chiquoine, Lindsay P; Abella, Scott R; Bowker, Matthew A

    2016-06-01

    Restoring biological soil crusts (biocrusts) in degraded drylands can contribute to recovery of ecosystem functions that have global implications, including erosion resistance and nutrient cycling. To examine techniques for restoring biocrusts, we conducted a replicated, factorial experiment on recently abandoned road surfaces by applying biocrust inoculation (salvaged and stored dry for two years), salvaged topsoil, an abiotic soil amendment (wood shavings), and planting of a dominant perennial shrub (Ambrosia dumosa). Eighteen months after treatments, we measured biocrust abundance and species composition, soil chlorophyll a content and fertility, and soil resistance to erosion. Biocrust addition significantly accelerated biocrust recovery on disturbed soils, including increasing lichen and moss cover and cyanobacteria colonization. Compared to undisturbed controls, inoculated plots had similar lichen and moss composition, recovered 43% of total cyanobacteria density, had similar soil chlorophyll content, and exhibited recovery of soil fertility and soil stability. Inoculation was the only treatment that generated lichen and moss cover. Topsoil application resulted in partial recovery of the cyanobacteria community and soil properties. Compared to untreated disturbed plots, topsoil application without inoculum increased cyanobacteria density by 186% and moderately improved soil chlorophyll and ammonium content and soil stability. Topsoil application produced 22% and 51% of the cyanobacteria density g⁻¹ soil compared to undisturbed and inoculated plots, respectively. Plots not treated with either topsoil or inoculum had significantly lower cyanobacteria density, soil chlorophyll and ammonium concentrations, and significantly higher soil nitrate concentration. Wood shavings and Ambrosia had no influence on biocrust lichen and moss species recovery but did affect cyanobacteria composition and soil fertility. Inoculation of severely disturbed soil with native

  20. Nitrogen Additions Affect Root Dynamics in a Boreal Forest Ecosystem

    NASA Astrophysics Data System (ADS)

    Turner, K. M.; Treseder, K. K.

    2004-12-01

    As with many ecosystems, North American boreal forests are increasingly subjected to anthropogenic nitrogen deposition. To examine potential effects on plant growth, we created nitrogen fertilization plots in three sites along an Alaskan fire chronosequence composed of forests aged 5, 17, and 80 years. Each site had been exposed to two years of nitrogen fertilization, with four control plots and four nitrogen plots per site. General observations indicate that aboveground net primary productivity appears to be nitrogen limited in each site. We hypothesized that nitrogen fertilization would positively influence root dynamics as well, with nitrogen additions resulting in an increase in standing root biomass and length. To test our hypothesis, we used a minirhizotron camera to collect sequential images of roots in the top 10 cm of soil in both nitrogen fertilized and control plots in each site. Images were collected monthly during the growing season, with a total of five sampling times between May 2003 and May 2004. We then analyzed the images with WinRhizotron root measurement software. Nitrogen fertilization had varying effects on root biomass among the three sites, with a significant site by N interaction (P = 0.039). A decrease in root biomass was observed in the 5 and 80 year old sites, dropping from 207 g/m2 to 79 g/m2 and from 230 g/m2 to 129 g/m2 for the youngest and oldest sites, respectively. In contrast, root biomass increased from 52 g/m2 to 107 g/m2 in the 17 year old site. (Values are for the top 10 cm of soil only, and likely underestimate total root stocks.) Patterns in standing root lengths diverged from those of root biomass, with a 2.5-fold overall increase under nitrogen fertilization across all sites (P = 0.004). There were no significant differences among sites in nitrogen response. Standing root biomass and length differed from one another in their responses to nitrogen fertilization because nitrogen additions decreased specific root weight (as g

  1. Decomposer diversity and identity influence plant diversity effects on ecosystem functioning.

    PubMed

    Eisenhauer, Nico; Reich, Peter B; Isbell, Forest

    2012-10-01

    Plant productivity and other ecosystem functions often increase with plant diversity at a local scale. Alongside various plant-centered explanations for this pattern, there is accumulating evidence that multi-trophic interactions shape this relationship. Here, we investigated for the first time if plant diversity effects on ecosystem functioning are mediated or driven by decomposer animal diversity and identity using a double-diversity microcosm experiment. We show that many ecosystem processes and ecosystem multifunctionality (herbaceous shoot biomass production, litter removal, and N uptake) were affected by both plant and decomposer diversity, with ecosystem process rates often being maximal at intermediate to high plant and decomposer diversity and minimal at both low plant and decomposer diversity. Decomposers relaxed interspecific plant competition by enlarging chemical (increased N uptake and surface-litter decomposition) and spatial (increasing deep-root biomass) habitat space and by promoting plant complementarity. Anecic earthworms and isopods functioned as key decomposers; although decomposer diversity effects did not solely rely on these two decomposer species, positive plant net biodiversity and complementarity effects only occurred in the absence of isopods and the presence of anecic earthworms. Using a structural equation model, we explained 76% of the variance in plant complementarity, identified direct and indirect effect paths, and showed that the presence of key decomposers accounted for approximately three-quarters of the explained variance. We conclude that decomposer animals have been underappreciated as contributing agents of plant diversity-ecosystem functioning relationships. Elevated decomposer performance at high plant diversity found in previous experiments likely positively feeds back to plant performance, thus contributing to the positive relationship between plant diversity and ecosystem functioning.

  2. Mechanisms driving change: altered species interactions and ecosystem function through global warming.

    PubMed

    Traill, Lochran W; Lim, Matthew L M; Sodhi, Navjot S; Bradshaw, Corey J A

    2010-09-01

    1. We review the mechanisms behind ecosystem functions, the processes that facilitate energy transfer along food webs, and the major processes that allow the cycling of carbon, oxygen and nitrogen, and use case studies to show how these have already been, and will continue to be, altered by global warming. 2. Increased temperatures will affect the interactions between heterotrophs and autotrophs (e.g. pollination and seed dispersal), and between heterotrophs (e.g. predators-prey, parasites/pathogens-hosts), with generally negative ramifications for important ecosystem services (functions that provide direct benefit to human society such as pollination) and potential for heightened species co-extinction rates. 3. Mitigation of likely impacts of warming will require, in particular, the maintenance of species diversity as insurance for the provision of basic ecosystem services. Key to this will be long-term monitoring and focused research that seek to maintain ecosystem resilience in the face of global warming. 4. We provide guidelines for pursuing research that quantifies the nexus between ecosystem function and global warming. These include documentation of key functional species groups within systems, and understanding the principal outcomes arising from direct and indirect effects of a rapidly warming environment. Localized and targeted research and monitoring, complemented with laboratory work, will determine outcomes for resilience and guide adaptive conservation responses and long-term planning.

  3. Microbes as Engines of Ecosystem Function: When Does Community Structure Enhance Predictions of Ecosystem Processes?

    PubMed

    Graham, Emily B; Knelman, Joseph E; Schindlbacher, Andreas; Siciliano, Steven; Breulmann, Marc; Yannarell, Anthony; Beman, J M; Abell, Guy; Philippot, Laurent; Prosser, James; Foulquier, Arnaud; Yuste, Jorge C; Glanville, Helen C; Jones, Davey L; Angel, Roey; Salminen, Janne; Newton, Ryan J; Bürgmann, Helmut; Ingram, Lachlan J; Hamer, Ute; Siljanen, Henri M P; Peltoniemi, Krista; Potthast, Karin; Bañeras, Lluís; Hartmann, Martin; Banerjee, Samiran; Yu, Ri-Qing; Nogaro, Geraldine; Richter, Andreas; Koranda, Marianne; Castle, Sarah C; Goberna, Marta; Song, Bongkeun; Chatterjee, Amitava; Nunes, Olga C; Lopes, Ana R; Cao, Yiping; Kaisermann, Aurore; Hallin, Sara; Strickland, Michael S; Garcia-Pausas, Jordi; Barba, Josep; Kang, Hojeong; Isobe, Kazuo; Papaspyrou, Sokratis; Pastorelli, Roberta; Lagomarsino, Alessandra; Lindström, Eva S; Basiliko, Nathan; Nemergut, Diana R

    2016-01-01

    Microorganisms are vital in mediating the earth's biogeochemical cycles; yet, despite our rapidly increasing ability to explore complex environmental microbial communities, the relationship between microbial community structure and ecosystem processes remains poorly understood. Here, we address a fundamental and unanswered question in microbial ecology: 'When do we need to understand microbial community structure to accurately predict function?' We present a statistical analysis investigating the value of environmental data and microbial community structure independently and in combination for explaining rates of carbon and nitrogen cycling processes within 82 global datasets. Environmental variables were the strongest predictors of process rates but left 44% of variation unexplained on average, suggesting the potential for microbial data to increase model accuracy. Although only 29% of our datasets were significantly improved by adding information on microbial community structure, we observed improvement in models of processes mediated by narrow phylogenetic guilds via functional gene data, and conversely, improvement in models of facultative microbial processes via community diversity metrics. Our results also suggest that microbial diversity can strengthen predictions of respiration rates beyond microbial biomass parameters, as 53% of models were improved by incorporating both sets of predictors compared to 35% by microbial biomass alone. Our analysis represents the first comprehensive analysis of research examining links between microbial community structure and ecosystem function. Taken together, our results indicate that a greater understanding of microbial communities informed by ecological principles may enhance our ability to predict ecosystem process rates relative to assessments based on environmental variables and microbial physiology. PMID:26941732

  4. Microbes as Engines of Ecosystem Function: When Does Community Structure Enhance Predictions of Ecosystem Processes?

    PubMed

    Graham, Emily B; Knelman, Joseph E; Schindlbacher, Andreas; Siciliano, Steven; Breulmann, Marc; Yannarell, Anthony; Beman, J M; Abell, Guy; Philippot, Laurent; Prosser, James; Foulquier, Arnaud; Yuste, Jorge C; Glanville, Helen C; Jones, Davey L; Angel, Roey; Salminen, Janne; Newton, Ryan J; Bürgmann, Helmut; Ingram, Lachlan J; Hamer, Ute; Siljanen, Henri M P; Peltoniemi, Krista; Potthast, Karin; Bañeras, Lluís; Hartmann, Martin; Banerjee, Samiran; Yu, Ri-Qing; Nogaro, Geraldine; Richter, Andreas; Koranda, Marianne; Castle, Sarah C; Goberna, Marta; Song, Bongkeun; Chatterjee, Amitava; Nunes, Olga C; Lopes, Ana R; Cao, Yiping; Kaisermann, Aurore; Hallin, Sara; Strickland, Michael S; Garcia-Pausas, Jordi; Barba, Josep; Kang, Hojeong; Isobe, Kazuo; Papaspyrou, Sokratis; Pastorelli, Roberta; Lagomarsino, Alessandra; Lindström, Eva S; Basiliko, Nathan; Nemergut, Diana R

    2016-01-01

    Microorganisms are vital in mediating the earth's biogeochemical cycles; yet, despite our rapidly increasing ability to explore complex environmental microbial communities, the relationship between microbial community structure and ecosystem processes remains poorly understood. Here, we address a fundamental and unanswered question in microbial ecology: 'When do we need to understand microbial community structure to accurately predict function?' We present a statistical analysis investigating the value of environmental data and microbial community structure independently and in combination for explaining rates of carbon and nitrogen cycling processes within 82 global datasets. Environmental variables were the strongest predictors of process rates but left 44% of variation unexplained on average, suggesting the potential for microbial data to increase model accuracy. Although only 29% of our datasets were significantly improved by adding information on microbial community structure, we observed improvement in models of processes mediated by narrow phylogenetic guilds via functional gene data, and conversely, improvement in models of facultative microbial processes via community diversity metrics. Our results also suggest that microbial diversity can strengthen predictions of respiration rates beyond microbial biomass parameters, as 53% of models were improved by incorporating both sets of predictors compared to 35% by microbial biomass alone. Our analysis represents the first comprehensive analysis of research examining links between microbial community structure and ecosystem function. Taken together, our results indicate that a greater understanding of microbial communities informed by ecological principles may enhance our ability to predict ecosystem process rates relative to assessments based on environmental variables and microbial physiology.

  5. Indicators of ecosystem function identify alternate states in the sagebrush steppe.

    PubMed

    Kachergis, Emily; Rocca, Monique E; Fernandez-Gimenez, Maria E

    2011-10-01

    Models of ecosystem change that incorporate nonlinear dynamics and thresholds, such as state-and-transition models (STMs), are increasingly popular tools for land management decision-making. However, few models are based on systematic collection and documentation of ecological data, and of these, most rely solely on structural indicators (species composition) to identify states and transitions. As STMs are adopted as an assessment framework throughout the United States, finding effective and efficient ways to create data-driven models that integrate ecosystem function and structure is vital. This study aims to (1) evaluate the utility of functional indicators (indicators of rangeland health, IRH) as proxies for more difficult ecosystem function measurements and (2) create a data-driven STM for the sagebrush steppe of Colorado, USA, that incorporates both ecosystem structure and function. We sampled soils, plant communities, and IRH at 41 plots with similar clayey soils but different site histories to identify potential states and infer the effects of management practices and disturbances on transitions. We found that many IRH were correlated with quantitative measures of functional indicators, suggesting that the IRH can be used to approximate ecosystem function. In addition to a reference state that functions as expected for this soil type, we identified four biotically and functionally distinct potential states, consistent with the theoretical concept of alternate states. Three potential states were related to management practices (chemical and mechanical shrub treatments and seeding history) while one was related only to ecosystem processes (erosion). IRH and potential states were also related to environmental variation (slope, soil texture), suggesting that there are environmental factors within areas with similar soils that affect ecosystem dynamics and should be noted within STMs. Our approach generated an objective, data-driven model of ecosystem dynamics

  6. Indicators of ecosystem function identify alternate states in the sagebrush steppe.

    PubMed

    Kachergis, Emily; Rocca, Monique E; Fernandez-Gimenez, Maria E

    2011-10-01

    Models of ecosystem change that incorporate nonlinear dynamics and thresholds, such as state-and-transition models (STMs), are increasingly popular tools for land management decision-making. However, few models are based on systematic collection and documentation of ecological data, and of these, most rely solely on structural indicators (species composition) to identify states and transitions. As STMs are adopted as an assessment framework throughout the United States, finding effective and efficient ways to create data-driven models that integrate ecosystem function and structure is vital. This study aims to (1) evaluate the utility of functional indicators (indicators of rangeland health, IRH) as proxies for more difficult ecosystem function measurements and (2) create a data-driven STM for the sagebrush steppe of Colorado, USA, that incorporates both ecosystem structure and function. We sampled soils, plant communities, and IRH at 41 plots with similar clayey soils but different site histories to identify potential states and infer the effects of management practices and disturbances on transitions. We found that many IRH were correlated with quantitative measures of functional indicators, suggesting that the IRH can be used to approximate ecosystem function. In addition to a reference state that functions as expected for this soil type, we identified four biotically and functionally distinct potential states, consistent with the theoretical concept of alternate states. Three potential states were related to management practices (chemical and mechanical shrub treatments and seeding history) while one was related only to ecosystem processes (erosion). IRH and potential states were also related to environmental variation (slope, soil texture), suggesting that there are environmental factors within areas with similar soils that affect ecosystem dynamics and should be noted within STMs. Our approach generated an objective, data-driven model of ecosystem dynamics

  7. Plant species richness and shrub cover attenuate drought effects on ecosystem functioning across Patagonian rangelands.

    PubMed

    Gaitán, Juan J; Bran, Donaldo; Oliva, Gabriel; Maestre, Fernando T; Aguiar, Martín R; Jobbágy, Esteban; Buono, Gustavo; Ferrante, Daniela; Nakamatsu, Viviana; Ciari, Georgina; Salomone, Jorge; Massara, Virginia

    2014-10-01

    Drought is an increasingly common phenomenon in drylands as a consequence of climate change. We used 311 sites across a broad range of environmental conditions in Patagonian rangelands to evaluate how drought severity and temperature (abiotic factors) and vegetation structure (biotic factors) modulate the impact of a drought event on the annual integral of normalized difference vegetation index (NDVI-I), our surrogate of ecosystem functioning. We found that NDVI-I decreases were larger with both increasing drought severity and temperature. Plant species richness (SR) and shrub cover (SC) attenuated the effects of drought on NDVI-I. Grass cover did not affect the impacts of drought on NDVI-I. Our results suggest that warming and species loss, two important imprints of global environmental change, could increase the vulnerability of Patagonian ecosystems to drought. Therefore, maintaining SR through appropriate grazing management can attenuate the adverse effects of climate change on ecosystem functioning.

  8. Plant species richness and shrub cover attenuate drought effects on ecosystem functioning across Patagonian rangelands

    PubMed Central

    Gaitán, Juan J.; Bran, Donaldo; Oliva, Gabriel; Maestre, Fernando T.; Aguiar, Martín R.; Jobbágy, Esteban; Buono, Gustavo; Ferrante, Daniela; Nakamatsu, Viviana; Ciari, Georgina; Salomone, Jorge; Massara, Virginia

    2014-01-01

    Drought is an increasingly common phenomenon in drylands as a consequence of climate change. We used 311 sites across a broad range of environmental conditions in Patagonian rangelands to evaluate how drought severity and temperature (abiotic factors) and vegetation structure (biotic factors) modulate the impact of a drought event on the annual integral of normalized difference vegetation index (NDVI-I), our surrogate of ecosystem functioning. We found that NDVI-I decreases were larger with both increasing drought severity and temperature. Plant species richness (SR) and shrub cover (SC) attenuated the effects of drought on NDVI-I. Grass cover did not affect the impacts of drought on NDVI-I. Our results suggest that warming and species loss, two important imprints of global environmental change, could increase the vulnerability of Patagonian ecosystems to drought. Therefore, maintaining SR through appropriate grazing management can attenuate the adverse effects of climate change on ecosystem functioning. PMID:25339654

  9. Plant species richness and shrub cover attenuate drought effects on ecosystem functioning across Patagonian rangelands.

    PubMed

    Gaitán, Juan J; Bran, Donaldo; Oliva, Gabriel; Maestre, Fernando T; Aguiar, Martín R; Jobbágy, Esteban; Buono, Gustavo; Ferrante, Daniela; Nakamatsu, Viviana; Ciari, Georgina; Salomone, Jorge; Massara, Virginia

    2014-10-01

    Drought is an increasingly common phenomenon in drylands as a consequence of climate change. We used 311 sites across a broad range of environmental conditions in Patagonian rangelands to evaluate how drought severity and temperature (abiotic factors) and vegetation structure (biotic factors) modulate the impact of a drought event on the annual integral of normalized difference vegetation index (NDVI-I), our surrogate of ecosystem functioning. We found that NDVI-I decreases were larger with both increasing drought severity and temperature. Plant species richness (SR) and shrub cover (SC) attenuated the effects of drought on NDVI-I. Grass cover did not affect the impacts of drought on NDVI-I. Our results suggest that warming and species loss, two important imprints of global environmental change, could increase the vulnerability of Patagonian ecosystems to drought. Therefore, maintaining SR through appropriate grazing management can attenuate the adverse effects of climate change on ecosystem functioning. PMID:25339654

  10. Emerging horizons in biodiversity and ecosystem functioning research.

    PubMed

    Reiss, Julia; Bridle, Jon R; Montoya, José M; Woodward, Guy

    2009-09-01

    Two decades of intensive research have provided compelling evidence for a link between biodiversity and ecosystem functioning (B-EF). Whereas early B-EF research concentrated on species richness and single processes, recent studies have investigated different measures of both biodiversity and ecosystem functioning, such as functional diversity and joint metrics of multiple processes. There is also a shift from viewing assemblages in terms of their contribution to particular processes toward placing them within a wider food web context. We review how the responses and predictors in B-EF experiments are quantified and how biodiversity effects are shaped by multitrophic interactions. Further, we discuss how B-EF metrics and food web relations could be addressed simultaneously. We conclude that addressing traits, multiple processes and food web interactions is needed to capture the mechanisms that underlie B-EF relations in natural assemblages.

  11. Biodiversity and ecosystem functioning in evolving food webs.

    PubMed

    Allhoff, K T; Drossel, B

    2016-05-19

    We use computer simulations in order to study the interplay between biodiversity and ecosystem functioning (BEF) during both the formation and the ongoing evolution of large food webs. A species in our model is characterized by its own body mass, its preferred prey body mass and the width of its potential prey body mass spectrum. On an ecological time scale, population dynamics determines which species are viable and which ones go extinct. On an evolutionary time scale, new species emerge as modifications of existing ones. The network structure thus emerges and evolves in a self-organized manner. We analyse the relation between functional diversity and five community level measures of ecosystem functioning. These are the metabolic loss of the predator community, the total biomasses of the basal and the predator community, and the consumption rates on the basal community and within the predator community. Clear BEF relations are observed during the initial build-up of the networks, or when parameters are varied, causing bottom-up or top-down effects. However, ecosystem functioning measures fluctuate only very little during long-term evolution under constant environmental conditions, despite changes in functional diversity. This result supports the hypothesis that trophic cascades are weaker in more complex food webs.

  12. Biodiversity and ecosystem functioning in evolving food webs.

    PubMed

    Allhoff, K T; Drossel, B

    2016-05-19

    We use computer simulations in order to study the interplay between biodiversity and ecosystem functioning (BEF) during both the formation and the ongoing evolution of large food webs. A species in our model is characterized by its own body mass, its preferred prey body mass and the width of its potential prey body mass spectrum. On an ecological time scale, population dynamics determines which species are viable and which ones go extinct. On an evolutionary time scale, new species emerge as modifications of existing ones. The network structure thus emerges and evolves in a self-organized manner. We analyse the relation between functional diversity and five community level measures of ecosystem functioning. These are the metabolic loss of the predator community, the total biomasses of the basal and the predator community, and the consumption rates on the basal community and within the predator community. Clear BEF relations are observed during the initial build-up of the networks, or when parameters are varied, causing bottom-up or top-down effects. However, ecosystem functioning measures fluctuate only very little during long-term evolution under constant environmental conditions, despite changes in functional diversity. This result supports the hypothesis that trophic cascades are weaker in more complex food webs. PMID:27114582

  13. Heterogeneity of hemiboreal forests in relation to ecosystems functioning.

    NASA Astrophysics Data System (ADS)

    Krasnov, Dmitrii; Noe, Steffen M.; Krasnova, Alisa; Niinemets, Ülo

    2015-04-01

    Heterogeneity is one of the key components of sustainable development of every living system. It provides the source for restocking of ecosystem living components, irregular distribution of nutrients and habitats. Main components of forest horizontal heterogeneity are related with horizontal distribution of dominant species, soil properties, topography and as natural as human disturbances. Soil as the main source for nutrients supply plays essential role in functioning terrestrial ecosystems. The understanding of spatial distribution principles of such soil properties as soil acidity, nutrients available for living organisms, soil moisture and temperature, soil density and the role of tree dominant and co-dominant species can give deeper knowledge about ecosystem functioning. Models based on this knowledge can be more precise and give possibilities to predict more exactly the behavior of ecosystem in terms of global climate changing. The aim of the project is to assess spatial distribution and changes in soil properties related to spatial distribution of vegetation, microtopography and landscape position. For this purpose we used 3D modelling of sample plots and soil profiles using photogrammetry. PhotoModelerScanner software from EOS System Inc. was used to create 3D models from photogrammetric images and GIS technology was used for soil mapping. The project was done in the frame of SMEAR Estonia.

  14. Spatial pattern enhances ecosystem functioning in an African savanna.

    PubMed

    Pringle, Robert M; Doak, Daniel F; Brody, Alison K; Jocqué, Rudy; Palmer, Todd M

    2010-05-25

    The finding that regular spatial patterns can emerge in nature from local interactions between organisms has prompted a search for the ecological importance of these patterns. Theoretical models have predicted that patterning may have positive emergent effects on fundamental ecosystem functions, such as productivity. We provide empirical support for this prediction. In dryland ecosystems, termite mounds are often hotspots of plant growth (primary productivity). Using detailed observations and manipulative experiments in an African savanna, we show that these mounds are also local hotspots of animal abundance (secondary and tertiary productivity): insect abundance and biomass decreased with distance from the nearest termite mound, as did the abundance, biomass, and reproductive output of insect-eating predators. Null-model analyses indicated that at the landscape scale, the evenly spaced distribution of termite mounds produced dramatically greater abundance, biomass, and reproductive output of consumers across trophic levels than would be obtained in landscapes with randomly distributed mounds. These emergent properties of spatial pattern arose because the average distance from an arbitrarily chosen point to the nearest feature in a landscape is minimized in landscapes where the features are hyper-dispersed (i.e., uniformly spaced). This suggests that the linkage between patterning and ecosystem functioning will be common to systems spanning the range of human management intensities. The centrality of spatial pattern to system-wide biomass accumulation underscores the need to conserve pattern-generating organisms and mechanisms, and to incorporate landscape patterning in efforts to restore degraded habitats and maximize the delivery of ecosystem services.

  15. Functional richness and ecosystem services: bird predation on arthropods in tropical agroecosystems.

    PubMed

    Philpott, Stacy M; Soong, Oliver; Lowenstein, Jacob H; Pulido, Astrid Luz; Lopez, Diego Tobar; Flynn, Dan F B; DeClerck, Fabrice

    2009-10-01

    In agroecosystems, biodiversity correlates with ecosystem function, yet mechanisms driving these relationships are often unknown. Examining traits and functional classifications of organisms providing ecosystem functions may provide insight into the mechanisms. Birds are important predators of insects, including pests. However, biological simplification of agroforests may decrease provisioning of this pest removal service by reducing bird taxonomic and functional diversity. A recent meta-analysis of bird exclosure studies from a range of agroecosystems in Central America concluded that higher bird richness is associated with significantly greater arthropod removal, yet the mechanism remains unclear. We conducted a meta-analysis of the same data to examine whether birds demonstrate functional complementarity in tropical agroforests. We classified birds according to relevant traits (body mass, foraging strategy, foraging Strata, and diet) and then examined how design of functional classification, including trait selection, classification methods, and the functional diversity metric used affect the suitability of different classifications as predictors of ecosystem services. We determined that vegetation characteristics are not likely drivers of arthropod removal by birds. For some functional classifications, functional richness positively correlated with arthropod removal, indicating that species complementarity may be an important mechanism behind this ecosystem function. The predictive ability of functional classifications increased with the number of traits included in the classification. For the two best classifications examined, functional group richness was a better predictor of arthropod reduction than other metrics of functional diversity (FD and Rao's Q). However, no functional classification predicted arthropod removal better than simple species richness; thus other factors may be important. Our analysis indicates that the sampling effect may also play a

  16. Risks of large-scale use of systemic insecticides to ecosystem functioning and services.

    PubMed

    Chagnon, Madeleine; Kreutzweiser, David; Mitchell, Edward A D; Morrissey, Christy A; Noome, Dominique A; Van der Sluijs, Jeroen P

    2015-01-01

    Large-scale use of the persistent and potent neonicotinoid and fipronil insecticides has raised concerns about risks to ecosystem functions provided by a wide range of species and environments affected by these insecticides. The concept of ecosystem services is widely used in decision making in the context of valuing the service potentials, benefits, and use values that well-functioning ecosystems provide to humans and the biosphere and, as an endpoint (value to be protected), in ecological risk assessment of chemicals. Neonicotinoid insecticides are frequently detected in soil and water and are also found in air, as dust particles during sowing of crops and aerosols during spraying. These environmental media provide essential resources to support biodiversity, but are known to be threatened by long-term or repeated contamination by neonicotinoids and fipronil. We review the state of knowledge regarding the potential impacts of these insecticides on ecosystem functioning and services provided by terrestrial and aquatic ecosystems including soil and freshwater functions, fisheries, biological pest control, and pollination services. Empirical studies examining the specific impacts of neonicotinoids and fipronil to ecosystem services have focused largely on the negative impacts to beneficial insect species (honeybees) and the impact on pollination service of food crops. However, here we document broader evidence of the effects on ecosystem functions regulating soil and water quality, pest control, pollination, ecosystem resilience, and community diversity. In particular, microbes, invertebrates, and fish play critical roles as decomposers, pollinators, consumers, and predators, which collectively maintain healthy communities and ecosystem integrity. Several examples in this review demonstrate evidence of the negative impacts of systemic insecticides on decomposition, nutrient cycling, soil respiration, and invertebrate populations valued by humans. Invertebrates

  17. Risks of large-scale use of systemic insecticides to ecosystem functioning and services.

    PubMed

    Chagnon, Madeleine; Kreutzweiser, David; Mitchell, Edward A D; Morrissey, Christy A; Noome, Dominique A; Van der Sluijs, Jeroen P

    2015-01-01

    Large-scale use of the persistent and potent neonicotinoid and fipronil insecticides has raised concerns about risks to ecosystem functions provided by a wide range of species and environments affected by these insecticides. The concept of ecosystem services is widely used in decision making in the context of valuing the service potentials, benefits, and use values that well-functioning ecosystems provide to humans and the biosphere and, as an endpoint (value to be protected), in ecological risk assessment of chemicals. Neonicotinoid insecticides are frequently detected in soil and water and are also found in air, as dust particles during sowing of crops and aerosols during spraying. These environmental media provide essential resources to support biodiversity, but are known to be threatened by long-term or repeated contamination by neonicotinoids and fipronil. We review the state of knowledge regarding the potential impacts of these insecticides on ecosystem functioning and services provided by terrestrial and aquatic ecosystems including soil and freshwater functions, fisheries, biological pest control, and pollination services. Empirical studies examining the specific impacts of neonicotinoids and fipronil to ecosystem services have focused largely on the negative impacts to beneficial insect species (honeybees) and the impact on pollination service of food crops. However, here we document broader evidence of the effects on ecosystem functions regulating soil and water quality, pest control, pollination, ecosystem resilience, and community diversity. In particular, microbes, invertebrates, and fish play critical roles as decomposers, pollinators, consumers, and predators, which collectively maintain healthy communities and ecosystem integrity. Several examples in this review demonstrate evidence of the negative impacts of systemic insecticides on decomposition, nutrient cycling, soil respiration, and invertebrate populations valued by humans. Invertebrates

  18. European seaweeds under pressure: Consequences for communities and ecosystem functioning

    NASA Astrophysics Data System (ADS)

    Mineur, Frédéric; Arenas, Francisco; Assis, Jorge; Davies, Andrew J.; Engelen, Aschwin H.; Fernandes, Francisco; Malta, Erik-jan; Thibaut, Thierry; Van Nguyen, Tu; Vaz-Pinto, Fátima; Vranken, Sofie; Serrão, Ester A.; De Clerck, Olivier

    2015-04-01

    Seaweed assemblages represent the dominant autotrophic biomass in many coastal environments, playing a central structural and functional role in several ecosystems. In Europe, seaweed assemblages are highly diverse systems. The combined seaweed flora of different European regions hold around 1550 species (belonging to nearly 500 genera), with new species continuously uncovered, thanks to the emergence of molecular tools. In this manuscript we review the effects of global and local stressors on European seaweeds, their communities, and ecosystem functioning. Following a brief review on the present knowledge on European seaweed diversity and distribution, and the role of seaweed communities in biodiversity and ecosystem functioning, we discuss the effects of biotic homogenization (invasive species) and global climate change (shifts in bioclimatic zones and ocean acidification) on the distribution of individual species and their effect on the structure and functioning of seaweed communities. The arrival of new introduced species (that already account for 5-10% of the European seaweeds) and the regional extirpation of native species resulting from oceans' climate change are creating new diversity scenarios with undetermined functional consequences. Anthropogenic local stressors create additional disruption often altering dramatically assemblage's structure. Hence, we discuss ecosystem level effects of such stressors like harvesting, trampling, habitat modification, overgrazing and eutrophication that impact coastal communities at local scales. Last, we conclude by highlighting significant knowledge gaps that need to be addressed to anticipate the combined effects of global and local stressors on seaweed communities. With physical and biological changes occurring at unexpected pace, marine phycologists should now integrate and join their research efforts to be able to contribute efficiently for the conservation and management of coastal systems.

  19. Carbon exchange between ecosystems and atmosphere in the Czech Republic is affected by climate factors.

    PubMed

    Marek, Michal V; Janouš, Dalibor; Taufarová, Klára; Havránková, Kateřina; Pavelka, Marian; Kaplan, Věroslav; Marková, Irena

    2011-05-01

    By comparing five ecosystem types in the Czech Republic over several years, we recorded the highest carbon sequestration potential in an evergreen Norway spruce forest (100%) and an agroecosystem (65%), followed by European beech forest (25%) and a wetland ecosystem (20%). Because of a massive ecosystem respiration, the final carbon gain of the grassland was negative. Climate was shown to be an important factor of carbon uptake by ecosystems: by varying the growing season length (a 22-d longer season in 2005 than in 2007 increased carbon sink by 13%) or by the effect of short- term synoptic situations (e.g. summer hot and dry days reduced net carbon storage by 58% relative to hot and wet days). Carbon uptake is strongly affected by the ontogeny and a production strategy which is demonstrated by the comparison of seasonal course of carbon uptake between coniferous (Norway spruce) and deciduous (European beech) stands.

  20. Can plant phloem properties affect the link between ecosystem assimilation and respiration?

    NASA Astrophysics Data System (ADS)

    Mencuccini, M.; Hölttä, T.; Sevanto, S.; Nikinmaa, E.

    2012-04-01

    Phloem transport of carbohydrates in plants under field conditions is currently not well understood. This is largely the result of the lack of techniques suitable for measuring phloem physiological properties continuously under field conditions. This lack of knowledge is currently hampering our efforts to link ecosystem-level processes of carbon fixation, allocation and use, especially belowground. On theoretical grounds, the properties of the transport pathway from canopy to roots must be important in affecting the link between carbon assimilation and respiration, but it is unclear whether their effect is partially or entirely masked by processes occurring in other parts of the ecosystem. One can also predict the characteristic time scales over which these effects should occur and, as consequence, predict whether the transfer of turgor and osmotic signals from the site of carbon assimilation to the sites of carbon use are likely to control respiration. We will present two sources of evidence suggesting that the properties of the phloem transport system may affect processes that are dependent on the supply of carbon substrate, such as root or soil respiration. Firstly, we will summarize the results of a literature survey on soil and ecosystem respiration where the speed of transfer of photosynthetic sugars from the plant canopy to the soil surface was determined. Estimates of the transfer speed could be grouped according to whether the study employed isotopic or canopy soil flux-based techniques. These two groups provided very different estimates of transfer times likely because transport of sucrose molecules, and pressure-concentration waves, in phloem differed. Secondly, we will argue that simultaneous measurements of bark and xylem diameters provide a novel tool to determine the continuous variations of phloem turgor in vivo in the field. We will present a model that interprets these changes in xylem and live bark diameters and present data testing the model

  1. Cascading effects of long-term land-use changes on plant traits and ecosystem functioning.

    PubMed

    Laliberté, Etienne; Tylianakis, Jason M

    2012-01-01

    There is much concern that the functioning of ecosystems will be affected by human-induced changes in biodiversity, of which land-use change is the most important driver. However, changes in biodiversity may be only one of many pathways through which land use alters ecosystem functioning, and its importance relative to other pathways remains unclear. In particular, although biodiversity-ecosystem function research has focused primarily on grasslands, the increases in agricultural inputs (e.g., fertilization, irrigation) and grazing pressure that drive change in grasslands worldwide have been largely ignored. Here we show that long-term (27-year) manipulations of soil resource availability and sheep grazing intensity caused marked, consistent shifts in grassland plant functional composition and diversity, with cascading (i.e., causal chains of) direct, indirect, and interactive effects on multiple ecosystem functions. Resource availability exerted dominant control over above-ground net primary production (ANPP), both directly and indirectly via shifts in plant functional composition. Importantly, the effects of plant functional diversity and grazing intensity on ANPP shifted from negative to positive as agricultural inputs increased, providing strong evidence that soil resource availability modulates the impacts of plant diversity and herbivory on primary production. These changes in turn altered litter decomposition and, ultimately, soil carbon sequestration, highlighting the relevance of ANPP as a key integrator of ecosystem functioning. Our study reveals how human alterations of bottom-up (resources) and top-down (herbivory) forces together interact to control the functioning of grazing systems, the most extensive land use on Earth.

  2. Real world biodiversity-ecosystem functioning: a seafloor perspective.

    PubMed

    Snelgrove, Paul V R; Thrush, Simon F; Wall, Diana H; Norkko, Alf

    2014-07-01

    The effective application of biodiversity-ecosystem function (BEF) research to societal needs amid the Anthropocene represents the next grand challenge for ecology. Biodiversity knowledge that is most meaningful to society must reconcile insights derived from theory with detailed experiments and broad-scale trends. This perspective requires science that addresses high species richness, redundancy, and natural variability, which simplified 'model systems' cannot mimic. Here, we illustrate solutions of biodiversity knowledge to management and societal problems that combine BEF with scaling experiments, analysis of BEF along environmental gradients, and mapping technologies. We primarily draw examples from biophysical interactions in seafloor environments, which cover 70% of the Earth and add significantly to global ecosystem functions and services.

  3. Real world biodiversity-ecosystem functioning: a seafloor perspective.

    PubMed

    Snelgrove, Paul V R; Thrush, Simon F; Wall, Diana H; Norkko, Alf

    2014-07-01

    The effective application of biodiversity-ecosystem function (BEF) research to societal needs amid the Anthropocene represents the next grand challenge for ecology. Biodiversity knowledge that is most meaningful to society must reconcile insights derived from theory with detailed experiments and broad-scale trends. This perspective requires science that addresses high species richness, redundancy, and natural variability, which simplified 'model systems' cannot mimic. Here, we illustrate solutions of biodiversity knowledge to management and societal problems that combine BEF with scaling experiments, analysis of BEF along environmental gradients, and mapping technologies. We primarily draw examples from biophysical interactions in seafloor environments, which cover 70% of the Earth and add significantly to global ecosystem functions and services. PMID:24932849

  4. The up-scaling of ecosystem functions in a heterogeneous world.

    PubMed

    Lohrer, Andrew M; Thrush, Simon F; Hewitt, Judi E; Kraan, Casper

    2015-05-20

    Earth is in the midst of a biodiversity crisis that is impacting the functioning of ecosystems and the delivery of valued goods and services. However, the implications of large scale species losses are often inferred from small scale ecosystem functioning experiments with little knowledge of how the dominant drivers of functioning shift across scales. Here, by integrating observational and manipulative experimental field data, we reveal scale-dependent influences on primary productivity in shallow marine habitats, thus demonstrating the scalability of complex ecological relationships contributing to coastal marine ecosystem functioning. Positive effects of key consumers (burrowing urchins, Echinocardium cordatum) on seafloor net primary productivity (NPP) elucidated by short-term, single-site experiments persisted across multiple sites and years. Additional experimentation illustrated how these effects amplified over time, resulting in greater primary producer biomass (sediment chlorophyll a content) in the longer term, depending on climatic context and habitat factors affecting the strengths of mutually reinforcing feedbacks [corrected]. The remarkable coherence of results from small and large scales is evidence of real-world ecosystem function scalability and ecological self-organisation. This discovery provides greater insights into the range of responses to broad-scale anthropogenic stressors in naturally heterogeneous environmental settings.

  5. Characterizations of how species mediate ecosystem properties require more comprehensive functional effect descriptors

    NASA Astrophysics Data System (ADS)

    Hale, R.; Mavrogordato, M. N.; Tolhurst, T. J.; Solan, M.

    2014-09-01

    The importance of individual species in mediating ecosystem process and functioning is generally accepted, but categorical descriptors that summarize species-specific contributions to ecosystems tend to reference a limited number of biological traits and underestimate the importance of how organisms interact with their environment. Here, we show how three functionally contrasting sediment-dwelling marine invertebrates affect fluid and particle transport - important processes in mediating nutrient cycling - and use high-resolution reconstructions of burrow geometry to determine the extent and nature of biogenic modification. We find that individual functional effect descriptors fall short of being able to adequately characterize how species mediate the stocks and flows of important ecosystem properties and that, in contrary to common practice and understanding, they are not substitutable with one another because they emphasize different aspects of species activity and behavior. When information derived from these metrics is combined with knowledge of how species behave and modify their environment, however, detailed mechanistic information emerges that increases the likelihood that a species functional standing will be appropriately summarized. Our study provides evidence that more comprehensive functional effect descriptors are required if they are to be of value to those tasked with projecting how altered biodiversity will influence future ecosystems.

  6. The up-scaling of ecosystem functions in a heterogeneous world

    NASA Astrophysics Data System (ADS)

    Lohrer, Andrew M.; Thrush, Simon F.; Hewitt, Judi E.; Kraan, Casper

    2015-05-01

    Earth is in the midst of a biodiversity crisis that is impacting the functioning of ecosystems and the delivery of valued goods and services. However, the implications of large scale species losses are often inferred from small scale ecosystem functioning experiments with little knowledge of how the dominant drivers of functioning shift across scales. Here, by integrating observational and manipulative experimental field data, we reveal scale-dependent influences on primary productivity in shallow marine habitats, thus demonstrating the scalability of complex ecological relationships contributing to coastal marine ecosystem functioning. Positive effects of key consumers (burrowing urchins, Echinocardium cordatum) on seafloor net primary productivity (NPP) elucidated by short-term, single-site experiments persisted across multiple sites and years. Additional experimentation illustrated how these effects amplified over time, resulting in greater primary producer biomass sediment chlorophyll a content (Chla) in the longer term, depending on climatic context and habitat factors affecting the strengths of mutually reinforcing feedbacks. The remarkable coherence of results from small and large scales is evidence of real-world ecosystem function scalability and ecological self-organisation. This discovery provides greater insights into the range of responses to broad-scale anthropogenic stressors in naturally heterogeneous environmental settings.

  7. The up-scaling of ecosystem functions in a heterogeneous world.

    PubMed

    Lohrer, Andrew M; Thrush, Simon F; Hewitt, Judi E; Kraan, Casper

    2015-01-01

    Earth is in the midst of a biodiversity crisis that is impacting the functioning of ecosystems and the delivery of valued goods and services. However, the implications of large scale species losses are often inferred from small scale ecosystem functioning experiments with little knowledge of how the dominant drivers of functioning shift across scales. Here, by integrating observational and manipulative experimental field data, we reveal scale-dependent influences on primary productivity in shallow marine habitats, thus demonstrating the scalability of complex ecological relationships contributing to coastal marine ecosystem functioning. Positive effects of key consumers (burrowing urchins, Echinocardium cordatum) on seafloor net primary productivity (NPP) elucidated by short-term, single-site experiments persisted across multiple sites and years. Additional experimentation illustrated how these effects amplified over time, resulting in greater primary producer biomass (sediment chlorophyll a content) in the longer term, depending on climatic context and habitat factors affecting the strengths of mutually reinforcing feedbacks [corrected]. The remarkable coherence of results from small and large scales is evidence of real-world ecosystem function scalability and ecological self-organisation. This discovery provides greater insights into the range of responses to broad-scale anthropogenic stressors in naturally heterogeneous environmental settings. PMID:25993477

  8. Inconsistent impacts of decomposer diversity on the stability of aboveground and belowground ecosystem functions

    PubMed Central

    Schädler, Martin

    2010-01-01

    The intensive discussion on the importance of biodiversity for the stability of essential processes in ecosystems has prompted a multitude of studies since the middle of the last century. Nevertheless, research has been extremely biased by focusing on the producer level, while studies on the impacts of decomposer diversity on the stability of ecosystem functions are lacking. Here, we investigate the impacts of decomposer diversity on the stability (reliability) of three important aboveground and belowground ecosystem functions: primary productivity (shoot and root biomass), litter decomposition, and herbivore infestation. For this, we analyzed the results of three laboratory experiments manipulating decomposer diversity (1–3 species) in comparison to decomposer-free treatments in terms of variability of the measured variables. Decomposer diversity often significantly but inconsistently affected the stability of all aboveground and belowground ecosystem functions investigated in the present study. While primary productivity was mainly destabilized, litter decomposition and aphid infestation were essentially stabilized by increasing decomposer diversity. However, impacts of decomposer diversity varied between plant community and fertility treatments. There was no general effect of the presence of decomposers on stability and no trend toward weaker effects in fertilized communities and legume communities. This indicates that impacts of decomposers are based on more than effects on nutrient availability. Although inconsistent impacts complicate the estimation of consequences of belowground diversity loss, underpinning mechanisms of the observed patterns are discussed. Impacts of decomposer diversity on the stability of essential ecosystem functions differed between plant communities of varying composition and fertility, implicating that human-induced changes of biodiversity and land-use management might have unpredictable effects on the processes mankind relies on

  9. Contrasting biodiversity-ecosystem functioning relationships in phylogenetic and functional diversity.

    PubMed

    Steudel, Bastian; Hallmann, Christine; Lorenz, Maike; Abrahamczyk, Stefan; Prinz, Kathleen; Herrfurth, Cornelia; Feussner, Ivo; Martini, Johannes W R; Kessler, Michael

    2016-10-01

    It is well known that ecosystem functioning is positively influenced by biodiversity. Most biodiversity-ecosystem functioning experiments have measured biodiversity based on species richness or phylogenetic relationships. However, theoretical and empirical evidence suggests that ecosystem functioning should be more closely related to functional diversity than to species richness. We applied different metrics of biodiversity in an artificial biodiversity-ecosystem functioning experiment using 64 species of green microalgae in combinations of two to 16 species. We found that phylogenetic and functional diversity were positively correlated with biomass overyield, driven by their strong correlation with species richness. At low species richness, no significant correlation between overyield and functional and phylogenetic diversity was found. However, at high species richness (16 species), we found a positive relationship of overyield with functional diversity and a negative relationship with phylogenetic diversity. We show that negative phylogenetic diversity-ecosystem functioning relationships can result from interspecific growth inhibition. The opposing performances of facilitation (functional diversity) and inhibition (phylogenetic diversity) we observed at the 16 species level suggest that phylogenetic diversity is not always a good proxy for functional diversity and that results from experiments with low species numbers may underestimate negative species interactions. PMID:27301904

  10. Contrasting biodiversity-ecosystem functioning relationships in phylogenetic and functional diversity.

    PubMed

    Steudel, Bastian; Hallmann, Christine; Lorenz, Maike; Abrahamczyk, Stefan; Prinz, Kathleen; Herrfurth, Cornelia; Feussner, Ivo; Martini, Johannes W R; Kessler, Michael

    2016-10-01

    It is well known that ecosystem functioning is positively influenced by biodiversity. Most biodiversity-ecosystem functioning experiments have measured biodiversity based on species richness or phylogenetic relationships. However, theoretical and empirical evidence suggests that ecosystem functioning should be more closely related to functional diversity than to species richness. We applied different metrics of biodiversity in an artificial biodiversity-ecosystem functioning experiment using 64 species of green microalgae in combinations of two to 16 species. We found that phylogenetic and functional diversity were positively correlated with biomass overyield, driven by their strong correlation with species richness. At low species richness, no significant correlation between overyield and functional and phylogenetic diversity was found. However, at high species richness (16 species), we found a positive relationship of overyield with functional diversity and a negative relationship with phylogenetic diversity. We show that negative phylogenetic diversity-ecosystem functioning relationships can result from interspecific growth inhibition. The opposing performances of facilitation (functional diversity) and inhibition (phylogenetic diversity) we observed at the 16 species level suggest that phylogenetic diversity is not always a good proxy for functional diversity and that results from experiments with low species numbers may underestimate negative species interactions.

  11. Functional identity and diversity of animals predict ecosystem functioning better than species-based indices.

    PubMed

    Gagic, Vesna; Bartomeus, Ignasi; Jonsson, Tomas; Taylor, Astrid; Winqvist, Camilla; Fischer, Christina; Slade, Eleanor M; Steffan-Dewenter, Ingolf; Emmerson, Mark; Potts, Simon G; Tscharntke, Teja; Weisser, Wolfgang; Bommarco, Riccardo

    2015-02-22

    Drastic biodiversity declines have raised concerns about the deterioration of ecosystem functions and have motivated much recent research on the relationship between species diversity and ecosystem functioning. A functional trait framework has been proposed to improve the mechanistic understanding of this relationship, but this has rarely been tested for organisms other than plants. We analysed eight datasets, including five animal groups, to examine how well a trait-based approach, compared with a more traditional taxonomic approach, predicts seven ecosystem functions below- and above-ground. Trait-based indices consistently provided greater explanatory power than species richness or abundance. The frequency distributions of single or multiple traits in the community were the best predictors of ecosystem functioning. This implies that the ecosystem functions we investigated were underpinned by the combination of trait identities (i.e. single-trait indices) and trait complementarity (i.e. multi-trait indices) in the communities. Our study provides new insights into the general mechanisms that link biodiversity to ecosystem functioning in natural animal communities and suggests that the observed responses were due to the identity and dominance patterns of the trait composition rather than the number or abundance of species per se.

  12. Functional identity and diversity of animals predict ecosystem functioning better than species-based indices

    PubMed Central

    Gagic, Vesna; Bartomeus, Ignasi; Jonsson, Tomas; Taylor, Astrid; Winqvist, Camilla; Fischer, Christina; Slade, Eleanor M.; Steffan-Dewenter, Ingolf; Emmerson, Mark; Potts, Simon G.; Tscharntke, Teja; Weisser, Wolfgang; Bommarco, Riccardo

    2015-01-01

    Drastic biodiversity declines have raised concerns about the deterioration of ecosystem functions and have motivated much recent research on the relationship between species diversity and ecosystem functioning. A functional trait framework has been proposed to improve the mechanistic understanding of this relationship, but this has rarely been tested for organisms other than plants. We analysed eight datasets, including five animal groups, to examine how well a trait-based approach, compared with a more traditional taxonomic approach, predicts seven ecosystem functions below- and above-ground. Trait-based indices consistently provided greater explanatory power than species richness or abundance. The frequency distributions of single or multiple traits in the community were the best predictors of ecosystem functioning. This implies that the ecosystem functions we investigated were underpinned by the combination of trait identities (i.e. single-trait indices) and trait complementarity (i.e. multi-trait indices) in the communities. Our study provides new insights into the general mechanisms that link biodiversity to ecosystem functioning in natural animal communities and suggests that the observed responses were due to the identity and dominance patterns of the trait composition rather than the number or abundance of species per se. PMID:25567651

  13. Microbes as Engines of Ecosystem Function: When Does Community Structure Enhance Predictions of Ecosystem Processes?

    PubMed Central

    Graham, Emily B.; Knelman, Joseph E.; Schindlbacher, Andreas; Siciliano, Steven; Breulmann, Marc; Yannarell, Anthony; Beman, J. M.; Abell, Guy; Philippot, Laurent; Prosser, James; Foulquier, Arnaud; Yuste, Jorge C.; Glanville, Helen C.; Jones, Davey L.; Angel, Roey; Salminen, Janne; Newton, Ryan J.; Bürgmann, Helmut; Ingram, Lachlan J.; Hamer, Ute; Siljanen, Henri M. P.; Peltoniemi, Krista; Potthast, Karin; Bañeras, Lluís; Hartmann, Martin; Banerjee, Samiran; Yu, Ri-Qing; Nogaro, Geraldine; Richter, Andreas; Koranda, Marianne; Castle, Sarah C.; Goberna, Marta; Song, Bongkeun; Chatterjee, Amitava; Nunes, Olga C.; Lopes, Ana R.; Cao, Yiping; Kaisermann, Aurore; Hallin, Sara; Strickland, Michael S.; Garcia-Pausas, Jordi; Barba, Josep; Kang, Hojeong; Isobe, Kazuo; Papaspyrou, Sokratis; Pastorelli, Roberta; Lagomarsino, Alessandra; Lindström, Eva S.; Basiliko, Nathan; Nemergut, Diana R.

    2016-01-01

    Microorganisms are vital in mediating the earth’s biogeochemical cycles; yet, despite our rapidly increasing ability to explore complex environmental microbial communities, the relationship between microbial community structure and ecosystem processes remains poorly understood. Here, we address a fundamental and unanswered question in microbial ecology: ‘When do we need to understand microbial community structure to accurately predict function?’ We present a statistical analysis investigating the value of environmental data and microbial community structure independently and in combination for explaining rates of carbon and nitrogen cycling processes within 82 global datasets. Environmental variables were the strongest predictors of process rates but left 44% of variation unexplained on average, suggesting the potential for microbial data to increase model accuracy. Although only 29% of our datasets were significantly improved by adding information on microbial community structure, we observed improvement in models of processes mediated by narrow phylogenetic guilds via functional gene data, and conversely, improvement in models of facultative microbial processes via community diversity metrics. Our results also suggest that microbial diversity can strengthen predictions of respiration rates beyond microbial biomass parameters, as 53% of models were improved by incorporating both sets of predictors compared to 35% by microbial biomass alone. Our analysis represents the first comprehensive analysis of research examining links between microbial community structure and ecosystem function. Taken together, our results indicate that a greater understanding of microbial communities informed by ecological principles may enhance our ability to predict ecosystem process rates relative to assessments based on environmental variables and microbial physiology. PMID:26941732

  14. Microbes as engines of ecosystem function: When does community structure enhance predictions of ecosystem processes?

    DOE PAGES

    Graham, Emily B.; Knelman, Joseph E.; Schindlbacher, Andreas; Siciliano, Steven; Breulmann, Marc; Yannarell, Anthony; Beman, J. M.; Abell, Guy; Philippot, Laurent; Prosser, James; et al

    2016-02-24

    In this study, microorganisms are vital in mediating the earth’s biogeochemical cycles; yet, despite our rapidly increasing ability to explore complex environmental microbial communities, the relationship between microbial community structure and ecosystem processes remains poorly understood. Here, we address a fundamental and unanswered question in microbial ecology: ‘When do we need to understand microbial community structure to accurately predict function?’ We present a statistical analysis investigating the value of environmental data and microbial community structure independently and in combination for explaining rates of carbon and nitrogen cycling processes within 82 global datasets. Environmental variables were the strongest predictors of processmore » rates but left 44% of variation unexplained on average, suggesting the potential for microbial data to increase model accuracy. Although only 29% of our datasets were significantly improved by adding information on microbial community structure, we observed improvement in models of processes mediated by narrow phylogenetic guilds via functional gene data, and conversely, improvement in models of facultative microbial processes via community diversity metrics. Our results also suggest that microbial diversity can strengthen predictions of respiration rates beyond microbial biomass parameters, as 53% of models were improved by incorporating both sets of predictors compared to 35% by microbial biomass alone. Our analysis represents the first comprehensive analysis of research examining links between microbial community structure and ecosystem function. Taken together, our results indicate that a greater understanding of microbial communities informed by ecological principles may enhance our ability to predict ecosystem process rates relative to assessments based on environmental variables and microbial physiology.« less

  15. Standardising the assessment of Functional Integrity in benthic ecosystems

    NASA Astrophysics Data System (ADS)

    de Juan, Silvia; Hewitt, Judi; Thrush, Simon; Freeman, Debbie

    2015-04-01

    Ecological integrity is an overarching concept that integrates multiple properties of ecosystems, including structure, function and resilience to external change. We explore the links between ecological integrity and structural surrogates for ecosystem functioning to develop a cost-effective assessment of Functional Integrity for marine habitats based on biological traits, abundance and heterogeneity, focused on the visible components of the seafloor, i.e., epibenthic flora and fauna and seabed biogenic habitat features. The assessment was based on diversity and redundancy of functional traits of the identified benthic components, supplemented by estimates of spatial heterogeneity (habitat transitions) and vertical habitat complexity. This approach was developed using video data collected in different years with different sampling strategies in two locations: Kawau Bay in North Island of New Zealand, and Port Pegasus in Stewart Island, off South Island of New Zealand; this last location was a priori expected to be nearly-pristine. Despite variability in sampling techniques and environmental settings, the approach proved effective and evidenced higher measures of Functional Integrity in the Port Pegasus location. This study introduces a first step to measure ecological integrity by successfully converting video data to surrogates of Functional Integrity, in a way expected to be habitat independent.

  16. Soil biota can change after exotic plant invasion: Does this affect ecosystem processes?

    USGS Publications Warehouse

    Belnap, J.; Phillips, S.L.; Sherrod, S.K.; Moldenke, A.

    2005-01-01

    Invasion of the exotic annual grass Bromus tectorum into stands of the native perennial grass Hilaria jamesii significantly reduced the abundance of soil biota, especially microarthropods and nematodes. Effects of invasion on active and total bacterial and fungal biomass were variable, although populations generally increased after 50+ years of invasion. The invasion of Bromus also resulted in a decrease in richness and a species shift in plants, microarthropods, fungi, and nematodes. However, despite the depauperate soil fauna at the invaded sites, no effects were seen on cellulose decomposition rates, nitrogen mineralization rates, or vascular plant growth. When Hilaria was planted into soils from not-invaded, recently invaded, and historically invaded sites (all currently or once dominated by Hilaria), germination and survivorship were not affected. In contrast, aboveground Hilaria biomass was significantly greater in recently invaded soils than in the other two soils. We attributed the Hilaria response to differences in soil nutrients present before the invasion, especially soil nitrogen, phosphorus, and potassium, as these nutrients were elevated in the soils that produced the greatest Hilaria biomass. Our data suggest that it is not soil biotic richness per se that determines soil process rates or plant productivity, but instead that either (1) the presence of a few critical soil food web taxa can keep ecosystem function high, (2) nutrient loss is very slow in this ecosystem, and/or (3) these processes are microbially driven. However, the presence of Bromus may reduce key soil nutrients over time and thus may eventually suppress native plant success. ?? 2005 by the Ecological Society of America.

  17. How does vineyard management intensity affect ecosystem services and disservices - insights from a meta-analysis

    NASA Astrophysics Data System (ADS)

    Winter, Silvia; Zaller, Johann G.; Kratschmer, Sophie; Pachinger, Bärbel; Strauss, Peter; Bauer, Thomas; Paredes, Daniel; Gómez, José A.; Guzmán, Gema; Landa, Blanca; Nicolai, Annegret; Burel, Francoise; Cluzeau, Daniel; Popescu, Daniela; Bunea, Claudiu-Ioan; Potthoff, Martin; Guernion, Muriel; Batáry, Péter

    2016-04-01

    Viticultural agro-ecosystems provide a range of different ecosystem services which are affected by management decisions of winegrowers. At the global scale, vineyards are often high intensity agricultural systems with bare soil or inter-row vegetation consisting of only a few plant species. These systems primarily aim at optimizing wine production by reducing competition for water and nutrients between grapevines and weeds and by preventing the outbreak of pests and diseases. At the same time, this kind of management is often associated with ecosystem disservices such as high rates of soil erosion, degradation of soil structure and fertility, contamination of groundwater and decline of biodiversity. Recently, several initiatives across the world tried to overcome detrimental effects of that management style by creating biodiversity friendly vineyards. The consequences of establishing divers cover crop mixes or tolerating spontaneous vegetation in vineyards for ecosystem services (including yield) overstretching local case studies has not been investigated yet. This meta-analysis will provide an overview of all published studies comparing the effects of different vineyard management practices on a range of different ecosystem services like biodiversity, pest control, pollination, soil conservation and carbon sequestration. The aggregated effect size will point out which management measures can provide the best overall net sum of ecosystem services. This meta-analysis is part of the transdisciplinary BiodivERsA project VineDivers and will ultimately lead into management and policy recommendations for various stakeholder groups engaged in viticulture.

  18. Global Human Footprint on the Linkage between Biodiversity and Ecosystem Functioning in Reef Fishes

    PubMed Central

    Mora, Camilo; Aburto-Oropeza, Octavio; Ayala Bocos, Arturo; Ayotte, Paula M.; Banks, Stuart; Bauman, Andrew G.; Beger, Maria; Bessudo, Sandra; Booth, David J.; Brokovich, Eran; Brooks, Andrew; Chabanet, Pascale; Cinner, Joshua E.; Cortés, Jorge; Cruz-Motta, Juan J.; Cupul Magaña, Amilcar; DeMartini, Edward E.; Edgar, Graham J.; Feary, David A.; Ferse, Sebastian C. A.; Friedlander, Alan M.; Gaston, Kevin J.; Gough, Charlotte; Graham, Nicholas A. J.; Green, Alison; Guzman, Hector; Hardt, Marah; Kulbicki, Michel; Letourneur, Yves; López Pérez, Andres; Loreau, Michel; Loya, Yossi; Martinez, Camilo; Mascareñas-Osorio, Ismael; Morove, Tau; Nadon, Marc-Olivier; Nakamura, Yohei; Paredes, Gustavo; Polunin, Nicholas V. C.; Pratchett, Morgan S.; Reyes Bonilla, Héctor; Rivera, Fernando; Sala, Enric; Sandin, Stuart A.; Soler, German; Stuart-Smith, Rick; Tessier, Emmanuel; Tittensor, Derek P.; Tupper, Mark; Usseglio, Paolo; Vigliola, Laurent; Wantiez, Laurent; Williams, Ivor; Wilson, Shaun K.; Zapata, Fernando A.

    2011-01-01

    Difficulties in scaling up theoretical and experimental results have raised controversy over the consequences of biodiversity loss for the functioning of natural ecosystems. Using a global survey of reef fish assemblages, we show that in contrast to previous theoretical and experimental studies, ecosystem functioning (as measured by standing biomass) scales in a non-saturating manner with biodiversity (as measured by species and functional richness) in this ecosystem. Our field study also shows a significant and negative interaction between human population density and biodiversity on ecosystem functioning (i.e., for the same human density there were larger reductions in standing biomass at more diverse reefs). Human effects were found to be related to fishing, coastal development, and land use stressors, and currently affect over 75% of the world's coral reefs. Our results indicate that the consequences of biodiversity loss in coral reefs have been considerably underestimated based on existing knowledge and that reef fish assemblages, particularly the most diverse, are greatly vulnerable to the expansion and intensity of anthropogenic stressors in coastal areas. PMID:21483714

  19. Phenological response of a key ecosystem function to biological invasion.

    PubMed

    Alp, Maria; Cucherousset, Julien; Buoro, Mathieu; Lecerf, Antoine

    2016-05-01

    Although climate warming has been widely demonstrated to induce shifts in the timing of many biological events, the phenological consequences of other prominent global change drivers remain largely unknown. Here, we investigated the effects of biological invasions on the seasonality of leaf litter decomposition, a crucial freshwater ecosystem function. Decomposition rates were quantified in 18 temperate shallow lakes distributed along a gradient of crayfish invasion and a temperature-based model was constructed to predict yearly patterns of decomposition. We found that, through direct detritus consumption, omnivorous invasive crayfish accelerated decomposition rates up to fivefold in spring, enhancing temperature dependence of the process and shortening the period of major detritus availability in the ecosystem by up to 39 days (95% CI: 15-61). The fact that our estimates are an order of magnitude higher than any previously reported climate-driven phenological shifts indicates that some powerful drivers of phenological change have been largely overlooked. PMID:26931804

  20. Spatial Pattern Enhances Ecosystem Functioning in an African Savanna

    PubMed Central

    Pringle, Robert M.; Doak, Daniel F.; Brody, Alison K.; Jocqué, Rudy; Palmer, Todd M.

    2010-01-01

    The finding that regular spatial patterns can emerge in nature from local interactions between organisms has prompted a search for the ecological importance of these patterns. Theoretical models have predicted that patterning may have positive emergent effects on fundamental ecosystem functions, such as productivity. We provide empirical support for this prediction. In dryland ecosystems, termite mounds are often hotspots of plant growth (primary productivity). Using detailed observations and manipulative experiments in an African savanna, we show that these mounds are also local hotspots of animal abundance (secondary and tertiary productivity): insect abundance and biomass decreased with distance from the nearest termite mound, as did the abundance, biomass, and reproductive output of insect-eating predators. Null-model analyses indicated that at the landscape scale, the evenly spaced distribution of termite mounds produced dramatically greater abundance, biomass, and reproductive output of consumers across trophic levels than would be obtained in landscapes with randomly distributed mounds. These emergent properties of spatial pattern arose because the average distance from an arbitrarily chosen point to the nearest feature in a landscape is minimized in landscapes where the features are hyper-dispersed (i.e., uniformly spaced). This suggests that the linkage between patterning and ecosystem functioning will be common to systems spanning the range of human management intensities. The centrality of spatial pattern to system-wide biomass accumulation underscores the need to conserve pattern-generating organisms and mechanisms, and to incorporate landscape patterning in efforts to restore degraded habitats and maximize the delivery of ecosystem services. PMID:20520846

  1. Parrots as key multilinkers in ecosystem structure and functioning.

    PubMed

    Blanco, Guillermo; Hiraldo, Fernando; Rojas, Abraham; Dénes, Francisco V; Tella, José L

    2015-09-01

    Mutually enhancing organisms can become reciprocal determinants of their distribution, abundance, and demography and thus influence ecosystem structure and dynamics. In addition to the prevailing view of parrots (Psittaciformes) as plant antagonists, we assessed whether they can act as plant mutualists in the dry tropical forest of the Bolivian inter-Andean valleys, an ecosystem particularly poor in vertebrate frugivores other than parrots (nine species). We hypothesised that if interactions between parrots and their food plants evolved as primarily or facultatively mutualistic, selection should have acted to maximize the strength of their interactions by increasing the amount and variety of resources and services involved in particular pairwise and community-wide interaction contexts. Food plants showed different growth habits across a wide phylogenetic spectrum, implying that parrots behave as super-generalists exploiting resources differing in phenology, type, biomass, and rewards from a high diversity of plants (113 species from 38 families). Through their feeding activities, parrots provided multiple services acting as genetic linkers, seed facilitators for secondary dispersers, and plant protectors, and therefore can be considered key mutualists with a pervasive impact on plant assemblages. The number of complementary and redundant mutualistic functions provided by parrots to each plant species was positively related to the number of different kinds of food extracted from them. These mutually enhancing interactions were reflected in species-level properties (e.g., biomass or dominance) of both partners, as a likely consequence of the temporal convergence of eco-(co)evolutionary dynamics shaping the ongoing structure and organization of the ecosystem. A full assessment of the, thus far largely overlooked, parrot-plant mutualisms and other ecological linkages could change the current perception of the role of parrots in the structure, organization, and

  2. Parrots as key multilinkers in ecosystem structure and functioning.

    PubMed

    Blanco, Guillermo; Hiraldo, Fernando; Rojas, Abraham; Dénes, Francisco V; Tella, José L

    2015-09-01

    Mutually enhancing organisms can become reciprocal determinants of their distribution, abundance, and demography and thus influence ecosystem structure and dynamics. In addition to the prevailing view of parrots (Psittaciformes) as plant antagonists, we assessed whether they can act as plant mutualists in the dry tropical forest of the Bolivian inter-Andean valleys, an ecosystem particularly poor in vertebrate frugivores other than parrots (nine species). We hypothesised that if interactions between parrots and their food plants evolved as primarily or facultatively mutualistic, selection should have acted to maximize the strength of their interactions by increasing the amount and variety of resources and services involved in particular pairwise and community-wide interaction contexts. Food plants showed different growth habits across a wide phylogenetic spectrum, implying that parrots behave as super-generalists exploiting resources differing in phenology, type, biomass, and rewards from a high diversity of plants (113 species from 38 families). Through their feeding activities, parrots provided multiple services acting as genetic linkers, seed facilitators for secondary dispersers, and plant protectors, and therefore can be considered key mutualists with a pervasive impact on plant assemblages. The number of complementary and redundant mutualistic functions provided by parrots to each plant species was positively related to the number of different kinds of food extracted from them. These mutually enhancing interactions were reflected in species-level properties (e.g., biomass or dominance) of both partners, as a likely consequence of the temporal convergence of eco-(co)evolutionary dynamics shaping the ongoing structure and organization of the ecosystem. A full assessment of the, thus far largely overlooked, parrot-plant mutualisms and other ecological linkages could change the current perception of the role of parrots in the structure, organization, and

  3. Ontogenetic functional diversity: size structure of a keystone predator drives functioning of a complex ecosystem.

    PubMed

    Rudolf, Volker H W; Rasmussen, Nick L

    2013-05-01

    A central challenge in community ecology is to understand the connection between biodiversity and the functioning of ecosystems. While traditional approaches have largely focused on species-level diversity, increasing evidence indicates that there exists substantial ecological diversity among individuals within species. By far, the largest source of this intraspecific diversity stems from variation among individuals in ontogenetic stage and size. Although such ontogenetic shifts are ubiquitous in natural communities, whether and how they scale up to influence the structure and functioning of complex ecosystems is largely unknown. Here we take an experimental approach to examine the consequences of ontogenetic niche shifts for the structure of communities and ecosystem processes. In particular we experimentally manipulated the stage structure in a keystone predator, larvae of the dragonfly Anax junius, in complex experimental pond communities to test whether changes in the population stage or size structure of a keystone species scale up to alter community structure and ecosystem processes, and how functional differences scale with relative differences in size among stages. We found that the functional role of A. junius was stage-specific. Altering what stages were present in a pond led to concurrent changes in community structure, primary producer biomass (periphyton and phytoplankton), and ultimately altered ecosystem processes (respiration and net primary productivity), indicating a strong, but stage-specific, trophic cascade. Interestingly, the stage-specific effects did not simply scale with size or biomass of the predator, but instead indicated clear ontogenetic niche shifts in ecological interactions. Thus, functional differences among stages within a keystone species scaled up to alter the functioning of entire ecosystems. Therefore, our results indicate that the classical approach of assuming an average functional role of a species can be misleading because

  4. Lead contamination of an old shooting range affecting the local ecosystem--A case study with a holistic approach.

    PubMed

    Rantalainen, Minna-Liisa; Torkkeli, Minna; Strömmer, Rauni; Setälä, Heikki

    2006-10-01

    The aim of this case study was to uncover the consequences of lead pellet-derived heavy lead contamination at a cast-off shooting range in southern Finland, covering aspects from soil chemistry and biology up to ecosystem level. The observed changes in the soil properties of the most contaminated areas suggest that the contamination may be disturbing processes of decomposition and nutrient mineralisation. Also two functionally important groups of soil organisms, microbes (as analysed using the PLFA analysis) and enchytraeid worms, were negatively affected by the contamination. Furthermore, there was an indication of reduced pine litter production at the contaminated areas. On the other hand, lead contamination appears not to have affected pine growth or soil-dwelling nematodes and microarthropods, and the general outlook of the whole ecosystem is that of a healthy forest. Thus, the boreal forest ecosystem studied as a whole appears to bear strong resistance to contamination, despite negative effects of lead on many of its components. This resistance may result from e.g. low bioavailability of lead, avoidance of the most contaminated soil horizons and microsites by the organisms, and functional redundancy and development of lead-tolerant populations amongst the organisms. The relative importance of these factors and the mechanisms behind them will be investigated in forthcoming studies.

  5. Effects on the function of Arctic ecosystems in the short- and long-term perspectives.

    PubMed

    Callaghan, Terry V; Björn, Lars Olof; Chernov, Yuri; Chapin, Terry; Christensen, Torben R; Huntley, Brian; Ims, Rolf A; Johansson, Margareta; Jolly, Dyanna; Jonasson, Sven; Matveyeva, Nadya; Panikov, Nicolai; Oechel, Walter; Shaver, Gus

    2004-11-01

    Historically, the function of Arctic ecosystems in terms of cycles of nutrients and carbon has led to low levels of primary production and exchanges of energy, water and greenhouse gases have led to low local and regional cooling. Sequestration of carbon from atmospheric CO2, in extensive, cold organic soils and the high albedo from low, snow-covered vegetation have had impacts on regional climate. However, many aspects of the functioning of Arctic ecosystems are sensitive to changes in climate and its impacts on biodiversity. The current Arctic climate results in slow rates of organic matter decomposition. Arctic ecosystems therefore tend to accumulate organic matter and elements despite low inputs. As a result, soil-available elements like nitrogen and phosphorus are key limitations to increases in carbon fixation and further biomass and organic matter accumulation. Climate warming is expected to increase carbon and element turnover, particularly in soils, which may lead to initial losses of elements but eventual, slow recovery. Individual species and species diversity have clear impacts on element inputs and retention in Arctic ecosystems. Effects of increased CO2 and UV-B on whole ecosystems, on the other hand, are likely to be small although effects on plant tissue chemisty, decomposition and nitrogen fixation may become important in the long-term. Cycling of carbon in trace gas form is mainly as CO2 and CH4. Most carbon loss is in the form of CO2, produced by both plants and soil biota. Carbon emissions as methane from wet and moist tundra ecosystems are about 5% of emissions as CO2 and are responsive to warming in the absence of any other changes. Winter processes and vegetation type also affect CH4 emissions as well as exchanges of energy between biosphere and atmosphere. Arctic ecosystems exhibit the largest seasonal changes in energy exchange of any terrestrial ecosystem because of the large changes in albedo from late winter, when snow reflects most

  6. The Sphagnum microbiome supports bog ecosystem functioning under extreme conditions.

    PubMed

    Bragina, Anastasia; Oberauner-Wappis, Lisa; Zachow, Christin; Halwachs, Bettina; Thallinger, Gerhard G; Müller, Henry; Berg, Gabriele

    2014-09-01

    Sphagnum-dominated bogs represent a unique yet widely distributed type of terrestrial ecosystem and strongly contribute to global biosphere functioning. Sphagnum is colonized by highly diverse microbial communities, but less is known about their function. We identified a high functional diversity within the Sphagnum microbiome applying an Illumina-based metagenomic approach followed by de novo assembly and MG-RAST annotation. An interenvironmental comparison revealed that the Sphagnum microbiome harbours specific genetic features that distinguish it significantly from microbiomes of higher plants and peat soils. The differential traits especially support ecosystem functioning by a symbiotic lifestyle under poikilohydric and ombrotrophic conditions. To realise a plasticity-stability balance, we found abundant subsystems responsible to cope with oxidative and drought stresses, to exchange (mobile) genetic elements, and genes that encode for resistance to detrimental environmental factors, repair and self-controlling mechanisms. Multiple microbe-microbe and plant-microbe interactions were also found to play a crucial role as indicated by diverse genes necessary for biofilm formation, interaction via quorum sensing and nutrient exchange. A high proportion of genes involved in nitrogen cycle and recycling of organic material supported the role of bacteria for nutrient supply. 16S rDNA analysis indicated a higher structural diversity than that which had been previously detected using PCR-dependent techniques. Altogether, the diverse Sphagnum microbiome has the ability to support the life of the host plant and the entire ecosystem under changing environmental conditions. Beyond this, the moss microbiome presents a promising bio-resource for environmental biotechnology - with respect to novel enzymes or stress-protecting bacteria. PMID:25113243

  7. Plant-microbe interactions as drivers of ecosystem functions relevant for the biodegradation of organic contaminants.

    PubMed

    Fester, Thomas; Giebler, Julia; Wick, Lukas Y; Schlosser, Dietmar; Kästner, Matthias

    2014-06-01

    The plant organism and associated microbial communities can be seen as a sunlight driven hotspot for the turnover of organic chemicals. In such environments the fate of a chemical will not only depend on its intrinsic structural stability toward (bio-)chemical reactions and its bioavailability but also on the functional effectiveness and stability of natural microbial communities as main drivers of natural attenuation of chemicals. Recent research demonstrates that interactions between plants and microorganisms are crucial for the biotransformation of organic chemicals, for various processes affecting the bioavailability of such compounds, and for the stability of the affected ecosystem. Practical bioremediation approaches, therefore, should encompass integrated measures targeting functional vegetation as well as functional microbial communities. Good examples for a successful practical approach are constructed wetlands, where an artificial, simplified ecosystem is used for the detoxification of organic contaminants. While such systems have considerable practical success, they are often treated as a black box and a sound mechanistic understanding of functional resilience and of the 'reactive power' of such plant-microbe ecosystems is poor. This situation has to change, if progress in the application of bioremediation is to be made.

  8. Comparison of the structure and function of Southern Ocean regional ecosystems: The Antarctic Peninsula and South Georgia

    NASA Astrophysics Data System (ADS)

    Murphy, E. J.; Hofmann, E. E.; Watkins, J. L.; Johnston, N. M.; Piñones, A.; Ballerini, T.; Hill, S. L.; Trathan, P. N.; Tarling, G. A.; Cavanagh, R. A.; Young, E. F.; Thorpe, S. E.; Fretwell, P.

    2013-01-01

    The ocean ecosystems around the west Antarctic Peninsula and South Georgia are two of the best described regional ecosystems of the Southern Ocean. They therefore provide a useful basis for developing comparative analyses of ocean ecosystems around the Antarctic. There are clear and expected differences in seasonality and species composition between the two ecosystems, but these mask an underlying similarity in ecosystem structure and function. This similarity results from the two ecosystems being part of a continuum, from more ice covered regions in the south to open water regions in the north. Within this continuum the major factors affecting ecosystem structure and function are the sea ice, the biogeochemical conditions and the connectivity generated by the flow of the Antarctic Circumpolar Current. Antarctic krill are central to the food web in both ecosystems, but the other species of plankton and predators present are different. These different species provide alternative pathways of energy transfer from primary production to the highest trophic levels. The relative dominance of these species can provide indicators of change in ecosystem structure and function. Both ecosystems are changing as a result of physically and biologically driven processes, and the ecological responses being observed are complex and variable across different species and within the two regions. Species in parts of the northern Antarctic Peninsula are being replaced by species that currently dominate farther north in more oceanic areas such as at South Georgia. The similarity of structure and strong connectivity, mean that projections of future change will require generic models of these ecosystems that can encompass changes in structure and function within a connected continuum from ice covered to open water in winter.

  9. Land use intensification alters ecosystem multifunctionality via loss of biodiversity and changes to functional composition.

    PubMed

    Allan, Eric; Manning, Pete; Alt, Fabian; Binkenstein, Julia; Blaser, Stefan; Blüthgen, Nico; Böhm, Stefan; Grassein, Fabrice; Hölzel, Norbert; Klaus, Valentin H; Kleinebecker, Till; Morris, E Kathryn; Oelmann, Yvonne; Prati, Daniel; Renner, Swen C; Rillig, Matthias C; Schaefer, Martin; Schloter, Michael; Schmitt, Barbara; Schöning, Ingo; Schrumpf, Marion; Solly, Emily; Sorkau, Elisabeth; Steckel, Juliane; Steffen-Dewenter, Ingolf; Stempfhuber, Barbara; Tschapka, Marco; Weiner, Christiane N; Weisser, Wolfgang W; Werner, Michael; Westphal, Catrin; Wilcke, Wolfgang; Fischer, Markus

    2015-08-01

    Global change, especially land-use intensification, affects human well-being by impacting the delivery of multiple ecosystem services (multifunctionality). However, whether biodiversity loss is a major component of global change effects on multifunctionality in real-world ecosystems, as in experimental ones, remains unclear. Therefore, we assessed biodiversity, functional composition and 14 ecosystem services on 150 agricultural grasslands differing in land-use intensity. We also introduce five multifunctionality measures in which ecosystem services were weighted according to realistic land-use objectives. We found that indirect land-use effects, i.e. those mediated by biodiversity loss and by changes to functional composition, were as strong as direct effects on average. Their strength varied with land-use objectives and regional context. Biodiversity loss explained indirect effects in a region of intermediate productivity and was most damaging when land-use objectives favoured supporting and cultural services. In contrast, functional composition shifts, towards fast-growing plant species, strongly increased provisioning services in more inherently unproductive grasslands.

  10. Soil restoration with organic amendments: linking cellular functionality and ecosystem processes

    NASA Astrophysics Data System (ADS)

    Bastida, F.; Selevsek, N.; Torres, I. F.; Hernández, T.; García, C.

    2015-10-01

    A hot topic in recent decades, the application of organic amendments to arid-degraded soils has been shown to benefit microbially-mediated processes. However, despite the importance of soils for global sustainability, a gap has not been addressed yet in soil science: is there any connection between ecosystem-community processes, cellular functionality, and microbial lifestyles (i.e. oligotrophy-copiotrophy) in restored soils? Together with classical ecosystem indicators (fatty-acids, extracellular-enzyme activities, basal respiration), state-of-the-art metaproteomics was applied to fill this gap in a model-restoration experiment initiated 10-years ago by the addition of sewage-sludge and compost. Organic amendment strongly impacted ecosystem processes. Furthermore, the type of material used induced differences in the cellular functionalities through variations in the percentages of proteins involved in translation, transcription, energy production and C-fixation. We conclude that the long-term impact of organic restoration goes beyond ecosystem processes and affects cellular functionalities and phyla-lifestyles coupled with differences in microbial-community structures.

  11. Soil restoration with organic amendments: linking cellular functionality and ecosystem processes.

    PubMed

    Bastida, F; Selevsek, N; Torres, I F; Hernández, T; García, C

    2015-10-27

    A hot topic in recent decades, the application of organic amendments to arid-degraded soils has been shown to benefit microbially-mediated processes. However, despite the importance of soils for global sustainability, a gap has not been addressed yet in soil science: is there any connection between ecosystem-community processes, cellular functionality, and microbial lifestyles (i.e. oligotrophy-copiotrophy) in restored soils? Together with classical ecosystem indicators (fatty-acids, extracellular-enzyme activities, basal respiration), state-of-the-art metaproteomics was applied to fill this gap in a model-restoration experiment initiated 10-years ago by the addition of sewage-sludge and compost. Organic amendment strongly impacted ecosystem processes. Furthermore, the type of material used induced differences in the cellular functionalities through variations in the percentages of proteins involved in translation, transcription, energy production and C-fixation. We conclude that the long-term impact of organic restoration goes beyond ecosystem processes and affects cellular functionalities and phyla-lifestyles coupled with differences in microbial-community structures.

  12. Soil restoration with organic amendments: linking cellular functionality and ecosystem processes

    PubMed Central

    Bastida, F.; Selevsek, N.; Torres, I. F.; Hernández, T.; García, C.

    2015-01-01

    A hot topic in recent decades, the application of organic amendments to arid-degraded soils has been shown to benefit microbially-mediated processes. However, despite the importance of soils for global sustainability, a gap has not been addressed yet in soil science: is there any connection between ecosystem-community processes, cellular functionality, and microbial lifestyles (i.e. oligotrophy-copiotrophy) in restored soils? Together with classical ecosystem indicators (fatty-acids, extracellular-enzyme activities, basal respiration), state-of-the-art metaproteomics was applied to fill this gap in a model-restoration experiment initiated 10-years ago by the addition of sewage-sludge and compost. Organic amendment strongly impacted ecosystem processes. Furthermore, the type of material used induced differences in the cellular functionalities through variations in the percentages of proteins involved in translation, transcription, energy production and C-fixation. We conclude that the long-term impact of organic restoration goes beyond ecosystem processes and affects cellular functionalities and phyla-lifestyles coupled with differences in microbial-community structures. PMID:26503516

  13. Soil restoration with organic amendments: linking cellular functionality and ecosystem processes.

    PubMed

    Bastida, F; Selevsek, N; Torres, I F; Hernández, T; García, C

    2015-01-01

    A hot topic in recent decades, the application of organic amendments to arid-degraded soils has been shown to benefit microbially-mediated processes. However, despite the importance of soils for global sustainability, a gap has not been addressed yet in soil science: is there any connection between ecosystem-community processes, cellular functionality, and microbial lifestyles (i.e. oligotrophy-copiotrophy) in restored soils? Together with classical ecosystem indicators (fatty-acids, extracellular-enzyme activities, basal respiration), state-of-the-art metaproteomics was applied to fill this gap in a model-restoration experiment initiated 10-years ago by the addition of sewage-sludge and compost. Organic amendment strongly impacted ecosystem processes. Furthermore, the type of material used induced differences in the cellular functionalities through variations in the percentages of proteins involved in translation, transcription, energy production and C-fixation. We conclude that the long-term impact of organic restoration goes beyond ecosystem processes and affects cellular functionalities and phyla-lifestyles coupled with differences in microbial-community structures. PMID:26503516

  14. Consequences of tropical land use for multitrophic biodiversity and ecosystem functioning.

    PubMed

    Barnes, Andrew D; Jochum, Malte; Mumme, Steffen; Haneda, Noor Farikhah; Farajallah, Achmad; Widarto, Tri Heru; Brose, Ulrich

    2014-01-01

    Our knowledge about land-use impacts on biodiversity and ecosystem functioning is mostly limited to single trophic levels, leaving us uncertain about whole-community biodiversity-ecosystem functioning relationships. We analyse consequences of the globally important land-use transformation from tropical forests to oil palm plantations. Species diversity, density and biomass of invertebrate communities suffer at least 45% decreases from rainforest to oil palm. Combining metabolic and food-web theory, we calculate annual energy fluxes to model impacts of land-use intensification on multitrophic ecosystem functioning. We demonstrate a 51% reduction in energy fluxes from forest to oil palm communities. Species loss clearly explains variation in energy fluxes; however, this relationship depends on land-use systems and functional feeding guilds, whereby predators are the most heavily affected. Biodiversity decline from forest to oil palm is thus accompanied by even stronger reductions in functionality, threatening to severely limit the functional resilience of communities to cope with future global changes. PMID:25350947

  15. Microbial composition affects the functioning of estuarine sediments

    PubMed Central

    Reed, Heather E; Martiny, Jennifer BH

    2013-01-01

    Although microorganisms largely drive many ecosystem processes, the relationship between microbial composition and their functioning remains unclear. To tease apart the effects of composition and the environment directly, microbial composition must be manipulated and maintained, ideally in a natural ecosystem. In this study, we aimed to test whether variability in microbial composition affects functional processes in a field setting, by reciprocally transplanting riverbed sediments between low- and high-salinity locations along the Nonesuch River (Maine, USA). We placed the sediments into microbial ‘cages' to prevent the migration of microorganisms, while allowing the sediments to experience the abiotic conditions of the surroundings. We performed two experiments, short- (1 week) and long-term (7 weeks) reciprocal transplants, after which we assayed a variety of functional processes in the cages. In both experiments, we examined the composition of bacteria generally (targeting the 16S rDNA gene) and sulfate-reducing bacteria (SRB) specifically (targeting the dsrAB gene) using terminal restriction fragment length polymorphism (T-RFLP). In the short-term experiment, sediment processes (CO2 production, CH4 flux, nitrification and enzyme activities) depended on both the sediment's origin (reflecting differences in microbial composition between salt and freshwater sediments) and the surrounding environment. In the long-term experiment, general bacterial composition (but not SRB composition) shifted in response to their new environment, and this composition was significantly correlated with sediment functioning. Further, sediment origin had a diminished effect, relative to the short-term experiment, on sediment processes. Overall, this study provides direct evidence that microbial composition directly affects functional processes in these sediments. PMID:23235294

  16. Ecosystem carbon storage capacity as affected by disturbance regimes: A general theoretical model

    SciTech Connect

    Weng, Ensheng; Luo, Yiqi; Wang, Weile; Wang, Han; Hayes, Daniel J; McGuire, A. David; Hastings, Alan; Schimel, David

    2012-01-01

    Disturbances have been recognized as a key factor shaping terrestrial ecosystem states and dynamics. A general model that quantitatively describes the relationship between carbon storage and disturbance regime is critical for better understanding large scale terrestrial ecosystem carbon dynamics. We developed a model (REGIME) to quantify ecosystem carbon storage capacities (E[x]) under varying disturbance regimes with an analytical solution E[x] = U {center_dot} {tau}{sub E} {center_dot} {lambda}{lambda} + s {tau} 1, where U is ecosystem carbon influx, {tau}{sub E} is ecosystem carbon residence time, and {tau}{sub 1} is the residence time of the carbon pool affected by disturbances (biomass pool in this study). The disturbance regime is characterized by the mean disturbance interval ({lambda}) and the mean disturbance severity (s). It is a Michaelis-Menten-type equation illustrating the saturation of carbon content with mean disturbance interval. This model analytically integrates the deterministic ecosystem carbon processes with stochastic disturbance events to reveal a general pattern of terrestrial carbon dynamics at large scales. The model allows us to get a sense of the sensitivity of ecosystems to future environmental changes just by a few calculations. According to the REGIME model, for example, approximately 1.8 Pg C will be lost in the high-latitude regions of North America (>45{sup o} N) if fire disturbance intensity increases around 5.7 time the current intensity to the end of the twenty-first century, which will require around 12% increases in net primary productivity (NPP) to maintain stable carbon stocks. If the residence time decreased 10% at the same time additional 12.5% increases in NPP are required to keep current C stocks. The REGIME model also lays the foundation for analytically modeling the interactions between deterministic biogeochemical processes and stochastic disturbance events.

  17. Functional consequences of realistic biodiversity changes in a marine ecosystem

    PubMed Central

    Bracken, Matthew E. S.; Friberg, Sara E.; Gonzalez-Dorantes, Cirse A.; Williams, Susan L.

    2008-01-01

    Declines in biodiversity have prompted concern over the consequences of species loss for the goods and services provided by natural ecosystems. However, relatively few studies have evaluated the functional consequences of realistic, nonrandom changes in biodiversity. Instead, most designs have used randomly selected assemblages from a local species pool to construct diversity gradients. It is therefore difficult, based on current evidence, to predict the functional consequences of realistic declines in biodiversity. In this study, we used tide pool microcosms to demonstrate that the effects of real-world changes in biodiversity may be very different from those of random diversity changes. Specifically, we measured the relationship between the diversity of a seaweed assemblage and its ability to use nitrogen, a key limiting nutrient in nearshore marine systems. We quantified nitrogen uptake using both experimental and model seaweed assemblages and found that natural increases in diversity resulted in enhanced rates of nitrogen use, whereas random diversity changes had no effect on nitrogen uptake. Our results suggest that understanding the real-world consequences of declining biodiversity will require addressing changes in species performance along natural diversity gradients and understanding the relationships between species' susceptibility to loss and their contributions to ecosystem functioning. PMID:18195375

  18. Disturbance legacies increase the resilience of forest ecosystem structure, composition, and functioning

    PubMed Central

    Seidl, Rupert; Rammer, Werner; Spies, Thomas A.

    2015-01-01

    Disturbances are key drivers of forest ecosystem dynamics, and forests are well adapted to their natural disturbance regimes. However, as a result of climate change, disturbance frequency is expected to increase in the future in many regions. It is not yet clear how such changes might affect forest ecosystems, and which mechanisms contribute to (current and future) disturbance resilience. We studied a 6364-ha landscape in the western Cascades of Oregon, USA, to investigate how patches of remnant old-growth trees (as one important class of biological legacies) affect the resilience of forest ecosystems to disturbance. Using the spatially explicit, individual-based, forest landscape model iLand, we analyzed the effect of three different levels of remnant patches (0%, 12%, and 24% of the landscape) on 500-year recovery trajectories after a large, high-severity wildfire. In addition, we evaluated how three different levels of fire frequency modulate the effects of initial legacies. We found that remnant live trees enhanced the recovery of total ecosystem carbon (TEC) stocks after disturbance, increased structural complexity of forest canopies, and facilitated the recolonization of late-seral species (LSS). Legacy effects were most persistent for indicators of species composition (still significant 500 years after disturbance), while TEC (i.e., a measure of ecosystem functioning) was least affected, with no significant differences among legacy scenarios after 236 years. Compounding disturbances were found to dampen legacy effects on all indicators, and higher initial legacy levels resulted in elevated fire severity in the second half of the study period. Overall, disturbance frequency had a stronger effect on ecosystem properties than the initial level of remnant old-growth trees. A doubling of the historically observed fire frequency to a mean fire return interval of 131 years reduced TEC by 10.5% and lowered the presence of LSS on the landscape by 18.1% on average

  19. Synergy of extreme drought and shrub invasion reduce ecosystem functioning and resilience in water-limited climates.

    PubMed

    Caldeira, Maria C; Lecomte, Xavier; David, Teresa S; Pinto, Joaquim G; Bugalho, Miguel N; Werner, Christiane

    2015-10-13

    Extreme drought events and plant invasions are major drivers of global change that can critically affect ecosystem functioning and alter ecosystem-atmosphere exchange. Invaders are expanding worldwide and extreme drought events are projected to increase in frequency and intensity. However, very little is known on how these drivers may interact to affect the functioning and resilience of ecosystems to extreme events. Using a manipulative shrub removal experiment and the co-occurrence of an extreme drought event (2011/2012) in a Mediterranean woodland, we show that native shrub invasion and extreme drought synergistically reduced ecosystem transpiration and the resilience of key-stone oak tree species. Ecosystem transpiration was dominated by the water use of the invasive shrub Cistus ladanifer, which further increased after the extreme drought event. Meanwhile, the transpiration of key-stone tree species decreased, indicating a competitive advantage in favour of the invader. Our results suggest that in Mediterranean-type climates the invasion of water spending species and projected recurrent extreme drought events may synergistically cause critical drought tolerance thresholds of key-stone tree species to be surpassed, corroborating observed higher tree mortality in the invaded ecosystems. Ultimately, this may shift seasonally water limited ecosystems into less desirable alternative states dominated by water spending invasive shrubs.

  20. Synergy of extreme drought and shrub invasion reduce ecosystem functioning and resilience in water-limited climates

    PubMed Central

    Caldeira, Maria C.; Lecomte, Xavier; David, Teresa S.; Pinto, Joaquim G.; Bugalho, Miguel N.; Werner, Christiane

    2015-01-01

    Extreme drought events and plant invasions are major drivers of global change that can critically affect ecosystem functioning and alter ecosystem-atmosphere exchange. Invaders are expanding worldwide and extreme drought events are projected to increase in frequency and intensity. However, very little is known on how these drivers may interact to affect the functioning and resilience of ecosystems to extreme events. Using a manipulative shrub removal experiment and the co-occurrence of an extreme drought event (2011/2012) in a Mediterranean woodland, we show that native shrub invasion and extreme drought synergistically reduced ecosystem transpiration and the resilience of key-stone oak tree species. Ecosystem transpiration was dominated by the water use of the invasive shrub Cistus ladanifer, which further increased after the extreme drought event. Meanwhile, the transpiration of key-stone tree species decreased, indicating a competitive advantage in favour of the invader. Our results suggest that in Mediterranean-type climates the invasion of water spending species and projected recurrent extreme drought events may synergistically cause critical drought tolerance thresholds of key-stone tree species to be surpassed, corroborating observed higher tree mortality in the invaded ecosystems. Ultimately, this may shift seasonally water limited ecosystems into less desirable alternative states dominated by water spending invasive shrubs. PMID:26461978

  1. Synergy of extreme drought and shrub invasion reduce ecosystem functioning and resilience in water-limited climates

    NASA Astrophysics Data System (ADS)

    Caldeira, Maria C.; Lecomte, Xavier; David, Teresa S.; Pinto, Joaquim G.; Bugalho, Miguel N.; Werner, Christiane

    2015-10-01

    Extreme drought events and plant invasions are major drivers of global change that can critically affect ecosystem functioning and alter ecosystem-atmosphere exchange. Invaders are expanding worldwide and extreme drought events are projected to increase in frequency and intensity. However, very little is known on how these drivers may interact to affect the functioning and resilience of ecosystems to extreme events. Using a manipulative shrub removal experiment and the co-occurrence of an extreme drought event (2011/2012) in a Mediterranean woodland, we show that native shrub invasion and extreme drought synergistically reduced ecosystem transpiration and the resilience of key-stone oak tree species. Ecosystem transpiration was dominated by the water use of the invasive shrub Cistus ladanifer, which further increased after the extreme drought event. Meanwhile, the transpiration of key-stone tree species decreased, indicating a competitive advantage in favour of the invader. Our results suggest that in Mediterranean-type climates the invasion of water spending species and projected recurrent extreme drought events may synergistically cause critical drought tolerance thresholds of key-stone tree species to be surpassed, corroborating observed higher tree mortality in the invaded ecosystems. Ultimately, this may shift seasonally water limited ecosystems into less desirable alternative states dominated by water spending invasive shrubs.

  2. Synergy of extreme drought and shrub invasion reduce ecosystem functioning and resilience in water-limited climates.

    PubMed

    Caldeira, Maria C; Lecomte, Xavier; David, Teresa S; Pinto, Joaquim G; Bugalho, Miguel N; Werner, Christiane

    2015-01-01

    Extreme drought events and plant invasions are major drivers of global change that can critically affect ecosystem functioning and alter ecosystem-atmosphere exchange. Invaders are expanding worldwide and extreme drought events are projected to increase in frequency and intensity. However, very little is known on how these drivers may interact to affect the functioning and resilience of ecosystems to extreme events. Using a manipulative shrub removal experiment and the co-occurrence of an extreme drought event (2011/2012) in a Mediterranean woodland, we show that native shrub invasion and extreme drought synergistically reduced ecosystem transpiration and the resilience of key-stone oak tree species. Ecosystem transpiration was dominated by the water use of the invasive shrub Cistus ladanifer, which further increased after the extreme drought event. Meanwhile, the transpiration of key-stone tree species decreased, indicating a competitive advantage in favour of the invader. Our results suggest that in Mediterranean-type climates the invasion of water spending species and projected recurrent extreme drought events may synergistically cause critical drought tolerance thresholds of key-stone tree species to be surpassed, corroborating observed higher tree mortality in the invaded ecosystems. Ultimately, this may shift seasonally water limited ecosystems into less desirable alternative states dominated by water spending invasive shrubs. PMID:26461978

  3. Animal diversity and ecosystem functioning in dynamic food webs

    NASA Astrophysics Data System (ADS)

    Schneider, Florian D.; Brose, Ulrich; Rall, Björn C.; Guill, Christian

    2016-10-01

    Species diversity is changing globally and locally, but the complexity of ecological communities hampers a general understanding of the consequences of animal species loss on ecosystem functioning. High animal diversity increases complementarity of herbivores but also increases feeding rates within the consumer guild. Depending on the balance of these counteracting mechanisms, species-rich animal communities may put plants under top-down control or may release them from grazing pressure. Using a dynamic food-web model with body-mass constraints, we simulate ecosystem functions of 20,000 communities of varying animal diversity. We show that diverse animal communities accumulate more biomass and are more exploitative on plants, despite their higher rates of intra-guild predation. However, they do not reduce plant biomass because the communities are composed of larger, and thus energetically more efficient, plant and animal species. This plasticity of community body-size structure reconciles the debate on the consequences of animal species loss for primary productivity.

  4. Animal diversity and ecosystem functioning in dynamic food webs

    PubMed Central

    Schneider, Florian D.; Brose, Ulrich; Rall, Björn C.; Guill, Christian

    2016-01-01

    Species diversity is changing globally and locally, but the complexity of ecological communities hampers a general understanding of the consequences of animal species loss on ecosystem functioning. High animal diversity increases complementarity of herbivores but also increases feeding rates within the consumer guild. Depending on the balance of these counteracting mechanisms, species-rich animal communities may put plants under top-down control or may release them from grazing pressure. Using a dynamic food-web model with body-mass constraints, we simulate ecosystem functions of 20,000 communities of varying animal diversity. We show that diverse animal communities accumulate more biomass and are more exploitative on plants, despite their higher rates of intra-guild predation. However, they do not reduce plant biomass because the communities are composed of larger, and thus energetically more efficient, plant and animal species. This plasticity of community body-size structure reconciles the debate on the consequences of animal species loss for primary productivity. PMID:27703157

  5. Phytoplankton traits predict ecosystem function in a global set of lakes.

    PubMed

    Zwart, Jacob A; Solomon, Christopher T; Jones, Stuart E

    2015-08-01

    Predicting ecosystem function from environmental conditions is a central goal of ecosystem ecology. However, many traditional ecosystem models are tailored for specific regions or ecosystem types, requiring several regional models to predict the same function. Alternatively, trait-based approaches have been effectively used to predict community structure in both terrestrial and aquatic environments and ecosystem function in a limited number of terrestrial examples. Here, we test the efficacy of a trait-based model in predicting gross primary production (GPP) in lake ecosystems. We incorporated data from >1000 United States lakes along with laboratory-generated phytoplankton trait data to build a trait-based model of GPP and then validated the model with GPP observations from a separate set of globally distributed lakes. The trait-based model performed as well as or outperformed two ecosystem models both spatially and temporally, demonstrating the efficacy of trait-based models for predicting ecosystem function over a range of environmental conditions.

  6. Re-connecting Urban Ecohydrology to Improve Ecosystem Functioning: The Role of Local-scale Green Infrastructure

    NASA Astrophysics Data System (ADS)

    Pavao-Zuckerman, M.

    2010-12-01

    As rates of urbanization continue to rise and a greater proportion of the population lives in urban and suburban areas, the provision of ecological services and functions become increasingly important to sustain human and environmental health in urban ecosystems. Soils play a primary role in the healthy functioning of ecosystems that provide supporting, provisioning, regulating, preserving, and cultural ecosystem services, yet developing our understanding of how urban soils function to provide these services within an ecological context is just getting underway. Soils in urban ecosytems are highly heterogeneous, and are affected by both direct and indirect influences and local modifications which alter their functioning relative to non-urbanized local soils. Here I discuss the functioning of rain gardens in and around Tucson, AZ, that have been installed in the urban landscape with the purpose of providing various ecosystem services to local residents and the greater urban ecosystem. This reconnection of ecohydrologic flows in the city has the potential to alter the structure and function of urban ecosystems in positive (through the increase in water availability) and negative (through the import of pollutants to soils) ways. This study compares soil properties, microbial function, and ecosystem functions within the urban ecosystem to determine how urbanization alters soils in semi-arid environments, and to determine if green urban modifications in desert cities can improve soils and ecosystem services. Soils in rain gardens have nearly twice the organic matter contents of native and urban soils, and correspondingly, greater microbial function (as indicated through respiration potential), higher abundance (through substrate induced respiration), and community complexity (indicated by a 3x increase in metabolic diversity) in these green design modifications. Net N-mineralization rates are almost 1.5 times faster in the rain garden basins than urban soils in general

  7. Does consideration of water routing affect simulated water and carbon dynamics in terrestrial ecosystems?

    NASA Astrophysics Data System (ADS)

    Tang, G.; Schneiderman, E. M.; Band, L. E.; Hwang, T.; Pierson, D. C.; Pradhanang, S. M.; Zion, M. S.

    2013-10-01

    The cycling of carbon in terrestrial ecosystems is closely coupled with the cycling of water. An important mechanism connecting ecological and hydrological processes in terrestrial ecosystems is lateral flow of water along landscapes. Few studies, however, have examined explicitly how consideration of water routing affects simulated water and carbon dynamics in terrestrial ecosystems. The objective of this study is to explore how consideration of water routing in a process-based hydroecological model affects simulated water and carbon dynamics. To achieve that end, we rasterized the regional hydroecological simulation systems (RHESSys) and employed the rasterized RHESSys (R-RHESSys) in a forested watershed. We performed and compared two contrasting simulations, one with and another without water routing. We found that R-RHESSys is able to correctly simulate major hydrological and ecological variables regardless of whether water routing is considered. When water routing was neglected, however, soil water table depth and saturation deficit were simulated to be smaller and spatially more homogeneous. As a result, evaporation, forest productivity and soil heterotrophic respiration also were simulated to be spatially more homogeneous compared to simulation with water routing. When averaged for the entire watershed, however, differences in simulated water and carbon fluxes are not significant between the two simulations. Overall, the study demonstrated that consideration of water routing enabled R-RHESSys to better capture our preconception of the spatial patterns of water table depth and saturation deficit across the watershed. Because the spatial pattern of soil moisture is fundamental to water efflux from land to the atmosphere, forest productivity and soil microbial activity, ecosystem and carbon cycle models, therefore, need to explicitly represent water routing in order to accurately quantify the magnitudes and patterns of water and carbon fluxes in terrestrial

  8. Delayed responses of an Arctic ecosystem to an extremely dry summer: impacts on net ecosystem exchange and vegetation functioning

    NASA Astrophysics Data System (ADS)

    Zona, D.; Lipson, D. A.; Richards, J. H.; Phoenix, G. K.; Liljedahl, A. K.; Ueyama, M.; Sturtevant, C. S.; Oechel, W. C.

    2013-12-01

    The importance and mode of action of extreme events on the global carbon budget are inadequately understood. This includes the differential impact of extreme events on various ecosystem components, lag effects, recovery times, and compensatory processes. Summer 2007 in Barrow, Arctic Alaska, experienced unusually high air temperatures (fifth warmest over a 65 yr period) and record low precipitation (lowest over a 65 yr period). These abnormal conditions resulted in strongly reduced net Sphagnum CO2 uptake, but no effect neither on vascular plant development nor on net ecosystem exchange (NEE) from this arctic tundra ecosystem. Gross primary production (GPP) and ecosystem respiration (Reco) were both generally greater during most of this extreme summer. Cumulative ecosystem C uptake in 2007 was similar to the previous summers, showing the capacity of the ecosystem to compensate in its net ecosystem exchange (NEE) despite the impact on other functions and structure such as substantial necrosis of the Sphagnum layer. Surprisingly, the lowest ecosystem C uptake (2005-2009) was observed during the 2008 summer, i.e the year directly following the extremely summer. In 2008, cumulative C uptake was ∼70% lower than prior years. This reduction cannot solely be attributed to mosses, which typically contribute with ∼40% - of the entire ecosystem C uptake. The minimum summer cumulative C uptake in 2008 suggests that the entire ecosystem experienced difficulty readjusting to more typical weather after experiencing exceptionally warm and dry conditions. Importantly, the return to a substantial cumulative C uptake occurred two summers after the extreme event, which suggest a high resilience of this tundra ecosystem. Overall, these results show a highly complex response of the C uptake and its sub-components to atypically dry conditions. The impact of multiple extreme events still awaits further investigation.

  9. Do biotic interactions modulate ecosystem functioning along stress gradients? Insights from semi-arid plant and biological soil crust communities

    PubMed Central

    Maestre, Fernando T.; Bowker, Matthew A.; Escolar, Cristina; Puche, María D.; Soliveres, Santiago; Maltez-Mouro, Sara; García-Palacios, Pablo; Castillo-Monroy, Andrea P.; Martínez, Isabel; Escudero, Adrián

    2010-01-01

    Climate change will exacerbate the degree of abiotic stress experienced by semi-arid ecosystems. While abiotic stress profoundly affects biotic interactions, their potential role as modulators of ecosystem responses to climate change is largely unknown. Using plants and biological soil crusts, we tested the relative importance of facilitative–competitive interactions and other community attributes (cover, species richness and species evenness) as drivers of ecosystem functioning along stress gradients in semi-arid Mediterranean ecosystems. Biotic interactions shifted from facilitation to competition along stress gradients driven by water availability and temperature. These changes were, however, dependent on the spatial scale and the community considered. We found little evidence to suggest that biotic interactions are a major direct influence upon indicators of ecosystem functioning (soil respiration, organic carbon, water-holding capacity, compaction and the activity of enzymes related to the carbon, nitrogen and phosphorus cycles) along stress gradients. However, attributes such as cover and species richness showed a direct effect on ecosystem functioning. Our results do not agree with predictions emphasizing that the importance of plant–plant interactions will be increased under climate change in dry environments, and indicate that reductions in the cover of plant and biological soil crust communities will negatively impact ecosystems under future climatic conditions. PMID:20513714

  10. Bird functional diversity decreases with time since disturbance: Does patchy prescribed fire enhance ecosystem function?.

    PubMed

    Sitters, Holly; Di Stefano, Julian; Christie, Fiona; Swan, Matthew; York, Alan

    2016-01-01

    Animal species diversity is often associated with time since disturbance, but the effects of disturbances such as fire on functional diversity are unknown. Functional diversity measures the range, abundance, and distribution of trait values in a community, and links changes in species composition with the consequences for ecosystem function. Improved understanding of the relationship between time since fire (TSF) and functional diversity is critical given that the frequency of both prescribed fire and wildfire is expected to increase. To address this knowledge gap, we examined responses of avian functional diversity to TSF and two direct measures of environmental heterogeneity, plant diversity, and structural heterogeneity. We surveyed birds across a 70-year chronosequence spanning four vegetation types in southeast Australia. Six bird functional traits were used to derive four functional diversity indices (richness, evenness, divergence, and dispersion) and the effects of TSF, plant diversity and structural heterogeneity on species richness and the functional diversity indices were examined using mixed models. We used a regression tree method to identify traits associated with species more common in young vegetation. Functional richness and dispersion were negatively associated with TSF in all vegetation types, suggesting that recent prescribed fire generates heterogeneous vegetation and provides greater opportunities for resource partitioning. Species richness was not significantly associated with TSF, and is probably an unreliable surrogate for functional diversity in fire-prone systems. A positive, relationship between functional evenness and structural heterogeneity was comnon to all vegetation types, suggesting that fine-scale (tens of meters) structural variation can enhance ecosystem function. Species more common in young vegetation were primarily linked by their specialist diets, indicating that ecosystem services such as seed dispersal and insect control

  11. Bird functional diversity decreases with time since disturbance: Does patchy prescribed fire enhance ecosystem function?.

    PubMed

    Sitters, Holly; Di Stefano, Julian; Christie, Fiona; Swan, Matthew; York, Alan

    2016-01-01

    Animal species diversity is often associated with time since disturbance, but the effects of disturbances such as fire on functional diversity are unknown. Functional diversity measures the range, abundance, and distribution of trait values in a community, and links changes in species composition with the consequences for ecosystem function. Improved understanding of the relationship between time since fire (TSF) and functional diversity is critical given that the frequency of both prescribed fire and wildfire is expected to increase. To address this knowledge gap, we examined responses of avian functional diversity to TSF and two direct measures of environmental heterogeneity, plant diversity, and structural heterogeneity. We surveyed birds across a 70-year chronosequence spanning four vegetation types in southeast Australia. Six bird functional traits were used to derive four functional diversity indices (richness, evenness, divergence, and dispersion) and the effects of TSF, plant diversity and structural heterogeneity on species richness and the functional diversity indices were examined using mixed models. We used a regression tree method to identify traits associated with species more common in young vegetation. Functional richness and dispersion were negatively associated with TSF in all vegetation types, suggesting that recent prescribed fire generates heterogeneous vegetation and provides greater opportunities for resource partitioning. Species richness was not significantly associated with TSF, and is probably an unreliable surrogate for functional diversity in fire-prone systems. A positive, relationship between functional evenness and structural heterogeneity was comnon to all vegetation types, suggesting that fine-scale (tens of meters) structural variation can enhance ecosystem function. Species more common in young vegetation were primarily linked by their specialist diets, indicating that ecosystem services such as seed dispersal and insect control

  12. Balancing Tradeoffs in Ecosystem Functions and Services in Grassland Management

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Managed grasslands are increasingly expected to provide ecosystem services beyond the traditional provision of food, feed, and fiber. Grassland systems can provide ecosystem services such as soil conservation, water quality protection, wildlife conservation, pleasing landscapes, soil carbon storage,...

  13. Revealing turning points in ecosystem functioning over the Northern Eurasian agricultural frontier.

    PubMed

    Horion, Stéphanie; Prishchepov, Alexander V; Verbesselt, Jan; de Beurs, Kirsten; Tagesson, Torbern; Fensholt, Rasmus

    2016-08-01

    The collapse of the Soviet Union in 1991 has been a turning point in the World history that left a unique footprint on the Northern Eurasian ecosystems. Conducting large scale mapping of environmental change and separating between naturogenic and anthropogenic drivers is a difficult endeavor in such highly complex systems. In this research a piece-wise linear regression method was used for breakpoint detection in Rain-Use Efficiency (RUE) time series and a classification of ecosystem response types was produced. Supported by earth observation data, field data, and expert knowledge, this study provides empirical evidence regarding the occurrence of drastic changes in RUE (assessment of the timing, the direction and the significance of these changes) in Northern Eurasian ecosystems between 1982 and 2011. About 36% of the study area (3.4 million km(2) ) showed significant (P < 0.05) trends and/or turning points in RUE during the observation period. A large proportion of detected turning points in RUE occurred around the fall of the Soviet Union in 1991 and in the following years which were attributed to widespread agricultural land abandonment. Our study also showed that recurrent droughts deeply affected vegetation productivity throughout the observation period, with a general worsening of the drought conditions in recent years. Moreover, recent human-induced turning points in ecosystem functioning were detected and attributed to ongoing recultivation and change in irrigation practices in the Volgograd region, and to increased salinization and increased grazing intensity around Lake Balkhash. The ecosystem-state assessment method introduced here proved to be a valuable support that highlighted hotspots of potentially altered ecosystems and allowed for disentangling human from climatic disturbances.

  14. Revealing turning points in ecosystem functioning over the Northern Eurasian agricultural frontier.

    PubMed

    Horion, Stéphanie; Prishchepov, Alexander V; Verbesselt, Jan; de Beurs, Kirsten; Tagesson, Torbern; Fensholt, Rasmus

    2016-08-01

    The collapse of the Soviet Union in 1991 has been a turning point in the World history that left a unique footprint on the Northern Eurasian ecosystems. Conducting large scale mapping of environmental change and separating between naturogenic and anthropogenic drivers is a difficult endeavor in such highly complex systems. In this research a piece-wise linear regression method was used for breakpoint detection in Rain-Use Efficiency (RUE) time series and a classification of ecosystem response types was produced. Supported by earth observation data, field data, and expert knowledge, this study provides empirical evidence regarding the occurrence of drastic changes in RUE (assessment of the timing, the direction and the significance of these changes) in Northern Eurasian ecosystems between 1982 and 2011. About 36% of the study area (3.4 million km(2) ) showed significant (P < 0.05) trends and/or turning points in RUE during the observation period. A large proportion of detected turning points in RUE occurred around the fall of the Soviet Union in 1991 and in the following years which were attributed to widespread agricultural land abandonment. Our study also showed that recurrent droughts deeply affected vegetation productivity throughout the observation period, with a general worsening of the drought conditions in recent years. Moreover, recent human-induced turning points in ecosystem functioning were detected and attributed to ongoing recultivation and change in irrigation practices in the Volgograd region, and to increased salinization and increased grazing intensity around Lake Balkhash. The ecosystem-state assessment method introduced here proved to be a valuable support that highlighted hotspots of potentially altered ecosystems and allowed for disentangling human from climatic disturbances. PMID:26929395

  15. Bioturbators enhance ecosystem function through complex biogeochemical interactions.

    PubMed

    Lohrer, Andrew M; Thrush, Simon F; Gibbs, Max M

    2004-10-28

    Predicting the consequences of species loss is critically important, given present threats to biological diversity such as habitat destruction, overharvesting and climate change. Several empirical studies have reported decreased ecosystem performance (for example, primary productivity) coincident with decreased biodiversity, although the relative influence of biotic effects and confounding abiotic factors has been vigorously debated. Whereas several investigations focused on single trophic levels (for example, grassland plants), studies of whole systems have revealed multiple layers of feedbacks, hidden drivers and emergent properties, making the consequences of species loss more difficult to predict. Here we report functionally important organisms and considerable biocomplexity in a sedimentary seafloor habitat, one of Earth's most widespread ecosystems. Experimental field measurements demonstrate how the abundance of spatangoid urchins--infaunal (in seafloor sediment) grazers/deposit feeders--is positively related to primary production, as their activities change nutrient fluxes and improve conditions for production by microphytobenthos (sedimentatry microbes and unicellular algae). Declines of spatangoid urchins after trawling are well documented, and our research linking these bioturbators to important benthic-pelagic fluxes highlights potential ramifications for productivity in coastal oceans.

  16. Testing the link between functional diversity and ecosystem functioning in a Minnesota grassland experiment.

    PubMed

    Clark, Christopher M; Flynn, Dan F B; Butterfield, Bradley J; Reich, Peter B

    2012-01-01

    The functional diversity of a community can influence ecosystem functioning and reflects assembly processes. The large number of disparate metrics used to quantify functional diversity reflects the range of attributes underlying this concept, generally summarized as functional richness, functional evenness, and functional divergence. However, in practice, we know very little about which attributes drive which ecosystem functions, due to a lack of field-based tests. Here we test the association between eight leading functional diversity metrics (Rao's Q, FD, FDis, FEve, FDiv, convex hull volume, and species and functional group richness) that emphasize different attributes of functional diversity, plus 11 extensions of these existing metrics that incorporate heterogeneous species abundances and trait variation. We assess the relationships among these metrics and compare their performances for predicting three key ecosystem functions (above- and belowground biomass and light capture) within a long-term grassland biodiversity experiment. Many metrics were highly correlated, although unique information was captured in FEve, FDiv, and dendrogram-based measures (FD) that were adjusted by abundance. FD adjusted by abundance outperformed all other metrics in predicting both above- and belowground biomass, although several others also performed well (e.g. Rao's Q, FDis, FDiv). More generally, trait-based richness metrics and hybrid metrics incorporating multiple diversity attributes outperformed evenness metrics and single-attribute metrics, results that were not changed when combinations of metrics were explored. For light capture, species richness alone was the best predictor, suggesting that traits for canopy architecture would be necessary to improve predictions. Our study provides a comprehensive test linking different attributes of functional diversity with ecosystem function for a grassland system.

  17. Size-dependent species removal impairs ecosystem functioning in a large-scale tropical field experiment.

    PubMed

    Dangles, Olivier; Carpio, Carlos; Woodward, Guy

    2012-12-01

    A major challenge of ecological research is to assess the functional consequences of species richness loss over time and space in global biodiversity hotspots, where extinctions are happening at an unprecedented rate. To address this issue, greater realism needs to be incorporated into both conceptual and experimental approaches. Here we propose a conceptual model that incorporates body size as a critical aspect of community responses to environmental change, which we tested in the Western Amazonian rain forest, one of the most speciose ecosystems on the planet. We employed an exclosure removal experiment (replicated under 10 microhabitats and four climatic conditions) in which we manipulated access to two types of resource by the whole community of dung and carrion beetles (> 60 species), depending on their size. Our 400 independent measurements revealed that changes in the number of species and functional groups, and temporal patterns in community composition, all affected resource burial rates, a key ecosystem process. Further, the functional contribution of species diversity in each size class was tightly dependent on beetle abundance, and while the role of large species could be performed by abundant smaller ones, and other naturally occurring decomposers, this was not the case when environmental conditions were harsher. These results demonstrate, for the first time in an animal assemblage in a tropical ecosystem, that although species may appear functionally redundant under one set of environmental conditions, many species would be needed to maintain ecosystem functioning at multiple temporal and spatial scales. This highlights the potential fragility of these systems to the ongoing global "Sixth Great Extinction," whose effects are likely to be especially pronounced in the Tropics.

  18. Effects of repeated salt pulses on ecosystem structure and functions in a stream mesocosm.

    PubMed

    Cañedo-Argüelles, Miguel; Bundschuh, Mirco; Gutiérrez-Cánovas, Cayetano; Kefford, Ben J; Prat, Narcís; Trobajo, Rosa; Schäfer, Ralf B

    2014-04-01

    Rivers and streams affected by mining activities often receive short-term sharp salinity increases due to water-soluble stockpiled materials being washed into receiving water bodies. We conducted a mesocosm study to explore the response of structural (diatom and stream invertebrate communities) and functional descriptors (chlorophyll a concentration, fungal biomass and leaf decomposition) to repeated short salinity pulses (3h of duration, with nominal electrical conductivities of 5, 10 and 15 mS cm(-1)), mimicking the exposure pattern occurring at salt-mine affected rivers. The experiment was conducted in 12 artificial flow-through stream systems over 16 days. The effect of the salt pulses on the ecosystem structure and functioning did not fully match most of our initial hypotheses, with the community response being weaker than predicted. The diatom community was, however, dominated by salt-tolerant species throughout the experiment, showing no consistent response to the treatment. The invertebrate response was associated with statistically significant changes in community structure (i.e. abundance of the different taxa) but no statistically significant changes in taxa richness. The salt pulses affected some functional descriptors of the ecosystem: fungal biomass exhibited a unimodal response to treatment magnitude, algal growth (i.e. chl a biomass) was hampered with increasing conductivity and leaf decomposition was significantly reduced in the high treatment. PMID:24503334

  19. Effects of repeated salt pulses on ecosystem structure and functions in a stream mesocosm.

    PubMed

    Cañedo-Argüelles, Miguel; Bundschuh, Mirco; Gutiérrez-Cánovas, Cayetano; Kefford, Ben J; Prat, Narcís; Trobajo, Rosa; Schäfer, Ralf B

    2014-04-01

    Rivers and streams affected by mining activities often receive short-term sharp salinity increases due to water-soluble stockpiled materials being washed into receiving water bodies. We conducted a mesocosm study to explore the response of structural (diatom and stream invertebrate communities) and functional descriptors (chlorophyll a concentration, fungal biomass and leaf decomposition) to repeated short salinity pulses (3h of duration, with nominal electrical conductivities of 5, 10 and 15 mS cm(-1)), mimicking the exposure pattern occurring at salt-mine affected rivers. The experiment was conducted in 12 artificial flow-through stream systems over 16 days. The effect of the salt pulses on the ecosystem structure and functioning did not fully match most of our initial hypotheses, with the community response being weaker than predicted. The diatom community was, however, dominated by salt-tolerant species throughout the experiment, showing no consistent response to the treatment. The invertebrate response was associated with statistically significant changes in community structure (i.e. abundance of the different taxa) but no statistically significant changes in taxa richness. The salt pulses affected some functional descriptors of the ecosystem: fungal biomass exhibited a unimodal response to treatment magnitude, algal growth (i.e. chl a biomass) was hampered with increasing conductivity and leaf decomposition was significantly reduced in the high treatment.

  20. Spatial Assessment of Forest Ecosystem Functions and Services using Human Relating Factors for SDG

    NASA Astrophysics Data System (ADS)

    Song, C.; Lee, W. K.; Jeon, S. W.; Kim, T.; Lim, C. H.

    2015-12-01

    Application of ecosystem service concept in environmental related decision making could be numerical and objective standard for policy maker between preserving and developing perspective of environment. However, pursuing maximum benefit from natural capital through ecosystem services caused failure by losing ecosystem functions through its trade-offs. Therefore, difference between ecosystem functions and services were demonstrated and would apply human relating perspectives. Assessment results of ecosystem functions and services can be divided 3 parts. Tree growth per year set as the ecosystem function factor and indicated through so called pure function map. After that, relating functions can be driven such as water conservation, air pollutant purification, climate change regulation, and timber production. Overall process and amount are numerically quantified. These functional results can be transferred to ecosystem services by multiplying economic unit value, so function reflecting service maps can be generated. On the other hand, above services, to implement more reliable human demand, human reflecting service maps are also be developed. As the validation, quantified ecosystem functions are compared with former results through pixel based analysis. Three maps are compared, and through comparing difference between ecosystem function and services and inversed trends in function based and human based service are analysed. In this study, we could find differences in PF, FRS, and HRS in relation to based ecosystem conditions. This study suggests that the differences in PF, FRS, and HRS should be understood in the decision making process for sustainable management of ecosystem services. Although the analysis is based on in sort existing process separation, it is important to consider the possibility of different usage of ecosystem function assessment results and ecosystem service assessment results in SDG policy making. Furthermore, process based functional approach

  1. The imprint of plants on ecosystem functioning: A data-driven approach

    NASA Astrophysics Data System (ADS)

    Musavi, Talie; Mahecha, Miguel D.; Migliavacca, Mirco; Reichstein, Markus; van de Weg, Martine Janet; van Bodegom, Peter M.; Bahn, Michael; Wirth, Christian; Reich, Peter B.; Schrodt, Franziska; Kattge, Jens

    2015-12-01

    Terrestrial ecosystems strongly determine the exchange of carbon, water and energy between the biosphere and atmosphere. These exchanges are influenced by environmental conditions (e.g., local meteorology, soils), but generally mediated by organisms. Often, mathematical descriptions of these processes are implemented in terrestrial biosphere models. Model implementations of this kind should be evaluated by empirical analyses of relationships between observed patterns of ecosystem functioning, vegetation structure, plant traits, and environmental conditions. However, the question of how to describe the imprint of plants on ecosystem functioning based on observations has not yet been systematically investigated. One approach might be to identify and quantify functional attributes or responsiveness of ecosystems (often very short-term in nature) that contribute to the long-term (i.e., annual but also seasonal or daily) metrics commonly in use. Here we define these patterns as "ecosystem functional properties", or EFPs. Such as the ecosystem capacity of carbon assimilation or the maximum light use efficiency of an ecosystem. While EFPs should be directly derivable from flux measurements at the ecosystem level, we posit that these inherently include the influence of specific plant traits and their local heterogeneity. We present different options of upscaling in situ measured plant traits to the ecosystem level (ecosystem vegetation properties - EVPs) and provide examples of empirical analyses on plants' imprint on ecosystem functioning by combining in situ measured plant traits and ecosystem flux measurements. Finally, we discuss how recent advances in remote sensing contribute to this framework.

  2. Ecosystem Function in Appalachian Headwater Streams during an Active Invasion by the Hemlock Woolly Adelgid

    PubMed Central

    Northington, Robert M.; Webster, Jackson R.; Benfield, Ernest F.; Cheever, Beth M.; Niederlehner, Barbara R.

    2013-01-01

    Forested ecosystems in the southeastern United States are currently undergoing an invasion by the hemlock woolly adelgid (HWA). Previous studies in this area have shown changes to forest structure, decreases in canopy cover, increases in organic matter, and changes to nutrient cycling on the forest floor and soil. Here, we were interested in how the effects of canopy loss and nutrient leakage from terrestrial areas would translate into functional changes in streams draining affected watersheds. We addressed these questions in HWA-infested watersheds at the Coweeta Hydrologic Laboratory in North Carolina. Specifically, we measured stream metabolism (gross primary production and ecosystem respiration) and nitrogen uptake from 2008 to 2011 in five streams across the Coweeta basin. Over the course of our study, we found no change to in-stream nutrient concentrations. While canopy cover decreased annually in these watersheds, this change in light penetration did not translate to higher rates of in-stream primary production during the summer months of our study. We found a trend towards greater heterotrophy within our watersheds, where in-stream respiration accounted for a much larger component of net ecosystem production than GPP. Additionally, increases in rhododendron cover may counteract changes in light and nutrient availability that occurred with hemlock loss. The variability in our metabolic and uptake parameters suggests an actively-infested ecosystem in transition between steady states. PMID:23613803

  3. Ecosystem function in Appalachian headwater streams during an active invasion by the hemlock woolly adelgid.

    PubMed

    Northington, Robert M; Webster, Jackson R; Benfield, Ernest F; Cheever, Beth M; Niederlehner, Barbara R

    2013-01-01

    Forested ecosystems in the southeastern United States are currently undergoing an invasion by the hemlock woolly adelgid (HWA). Previous studies in this area have shown changes to forest structure, decreases in canopy cover, increases in organic matter, and changes to nutrient cycling on the forest floor and soil. Here, we were interested in how the effects of canopy loss and nutrient leakage from terrestrial areas would translate into functional changes in streams draining affected watersheds. We addressed these questions in HWA-infested watersheds at the Coweeta Hydrologic Laboratory in North Carolina. Specifically, we measured stream metabolism (gross primary production and ecosystem respiration) and nitrogen uptake from 2008 to 2011 in five streams across the Coweeta basin. Over the course of our study, we found no change to in-stream nutrient concentrations. While canopy cover decreased annually in these watersheds, this change in light penetration did not translate to higher rates of in-stream primary production during the summer months of our study. We found a trend towards greater heterotrophy within our watersheds, where in-stream respiration accounted for a much larger component of net ecosystem production than GPP. Additionally, increases in rhododendron cover may counteract changes in light and nutrient availability that occurred with hemlock loss. The variability in our metabolic and uptake parameters suggests an actively-infested ecosystem in transition between steady states.

  4. Functional Diversity of Boreal Bog Plant Species Decreases Seasonal Variation of Ecosystem Carbon Sink Function

    NASA Astrophysics Data System (ADS)

    Korrensalo, A.

    2015-12-01

    Species diversity has been found to decrease the temporal variance of productivity of a plant community, and diversity in species responses to environmental factors seems to make a plant community more stable in changing conditions. Boreal bogs are nutrient poor peatland ecosystems where the number of plant species is low but the species differ greatly in their growth form. In here we aim to assess the role of the variation in photosynthesis between species for the temporal variation in ecosystem carbon sink function. To quantify the photosynthetic properties and their seasonal variation for different bog plant species we measured photosynthetic parameters and stress-inducing chlorophyll fluorescence of vascular plant and Sphagnum moss species in a boreal bog over a growing season. We estimated monthly gross photosynthesis (PG) of the whole study site based on species level light response curves and leaf area development. The estimated PG was further compared with a gross primary production (GPP) estimate measured by eddy covariance (EC) technique. The sum of upscaled PG estimates agreed well with the GPP estimate measured by the EC technique. The contributions of the species and species groups to the ecosystem level PG changed over the growing season. The sharp mid-summer peak in sedge PG was balanced by more stable PG of evergreen shrubs and Sphagna. Species abundance rather than differences in photosynthetic properties between species and growth forms determined the most productive plants on the ecosystem scale. Sphagna had lower photosynthesis and clorophyll fluorescence than vascular plants but were more productive on the ecosystem scale throughout the growing season due to their high areal coverage. These results show that the diversity of growth forms stabilizes the seasonal variation of the ecosystem level PG in an ombrotrophic bog ecosystem. This may increase the resilience of the ecosystem to changing environmental conditions.

  5. Habitat structure, trophic structure and ecosystem function: interactive effects in a bromeliad-insect community.

    PubMed

    Srivastava, Diane S

    2006-09-01

    Although previous studies have shown that ecosystem functions are affected by either trophic structure or habitat structure, there has been little consideration of their combined effects. Such interactions may be particularly important in systems where habitat and trophic structure covary. I use the aquatic insects in bromeliads to examine the combined effects of trophic structure and habitat structure on a key ecosystem function: detrital processing. In Costa Rican bromeliads, trophic structure naturally covaries with both habitat complexity and habitat size, precluding any observational analysis of interactions between factors. I therefore designed mesocosms that allowed each factor to be manipulated separately. Increases in mesocosm complexity reduced predator (damselfly larva) efficiency, resulting in high detritivore abundances, indirectly increasing detrital processing rates. However, increased complexity also directly reduced the per capita foraging efficiency of the detritivores. Over short time periods, these trends effectively cancelled each other out in terms of detrital processing. Over longer time periods, more complex patterns emerged. Increases in mesocosm size also reduced both predator efficiency and detritivore efficiency, leading to no net effect on detrital processing. In many systems, ecosystem functions may be impacted by strong interactions between trophic structure and habitat structure, cautioning against examining either effect in isolation.

  6. Soil ecosystem function under native and exotic plant assemblages as alternative states of successional grasslands

    NASA Astrophysics Data System (ADS)

    Spirito, Florencia; Yahdjian, Laura; Tognetti, Pedro M.; Chaneton, Enrique J.

    2014-01-01

    Old fields often become dominated by exotic plants establishing persistent community states. Ecosystem functioning may differ widely between such novel communities and the native-dominated counterparts. We evaluated soil ecosystem attributes in native and exotic (synthetic) grass assemblages established on a newly abandoned field, and in remnants of native grassland in the Inland Pampa, Argentina. We asked whether exotic species alter soil functioning through the quality of the litter they shed or by changing the decomposition environment. Litter decomposition of the exotic dominant Festuca arundinacea in exotic assemblages was faster than that of the native dominant Paspalum quadrifarium in native assemblages and remnant grasslands. Decomposition of a standard litter (Triticum aestivum) was also faster in exotic assemblages than in native assemblages and remnant grasslands. In a common garden, F. arundinacea showed higher decay rates than P. quadrifarium, which reflected the higher N content and lower C:N of the exotic grass litter. Soil respiration rates were higher in the exotic than in the native assemblages and remnant grasslands. Yet there were no significant differences in soil N availability or net N mineralization between exotic and native assemblages. Our results suggest that exotic grass dominance affected ecosystem function by producing a more decomposable leaf litter and by increasing soil decomposer activity. These changes might contribute to the extended dominance of fast-growing exotic grasses during old-field succession. Further, increased organic matter turnover under novel, exotic communities could reduce the carbon storage capacity of the system in the long term.

  7. Adding ecosystem function to agent-based land use models

    PubMed Central

    Yadav, V.; Del Grosso, S.J.; Parton, W.J.; Malanson, G.P.

    2015-01-01

    The objective of this paper is to examine issues in the inclusion of simulations of ecosystem functions in agent-based models of land use decision-making. The reasons for incorporating these simulations include local interests in land fertility and global interests in carbon sequestration. Biogeochemical models are needed in order to calculate such fluxes. The Century model is described with particular attention to the land use choices that it can encompass. When Century is applied to a land use problem the combinatorial choices lead to a potentially unmanageable number of simulation runs. Century is also parameter-intensive. Three ways of including Century output in agent-based models, ranging from separately calculated look-up tables to agents running Century within the simulation, are presented. The latter may be most efficient, but it moves the computing costs to where they are most problematic. Concern for computing costs should not be a roadblock. PMID:26191077

  8. How plant functional traits cascade to microbial function and ecosystem services in mountain grasslands

    NASA Astrophysics Data System (ADS)

    Lavorel, S.; Grigulis, K.; Krainer, U.; Legay, N.; Turner, C.; Dumont, M.; Kastl, E.; Arnoldi, C.; Bardgett, R.; Poly, F.; Pommier, T.; Schloter, M.; Tappeiner, U.; Bahn, M.; Clément, J.-C.

    2012-04-01

    1. There is growing evidence that plant functional diversity and microbial communities of soil are tightly coupled, and that this coupling influences a range of ecosystem functions. Moreover, it has been hypothesized that changes in the nature of interactions between plant functional diversity and microbial communities along environmental gradients contributes to variation in the delivery of ecosystem services. Although there is empirical support for such relationships using broad plant and microbial functional classifications, or from studies of plant monocultures, such relationships and their consequences for ecosystem services have not been quantified under complex field conditions with diverse plant communities. 2. We aimed to provide an explicit quantification of how plant and microbial functional properties interplay to determine key ecosystem functions underlying ecosystem services provided by grasslands. At three mountain grassland sites in the French Alps, Austrian Tyrol and northern England, we quantified, along gradients of management intensity, (i) plant functional diversity, (ii) soil microbial community composition and parameters associated with nitrogen cycling, and (iii) key ecosystem processes related to the carbon and nitrogen cycles including aboveground biomass production, standing litter, litter decomposition, soil organic matter and nitrate and ammonium leaching . Considering that plants strongly determine microbial communities, we used a hierarchical approach that considered first direct effects of plant traits and then effects of soil microorganisms on processes, to determine the relative effects of plant and microbial functional parameters on key ecosystem properties. 3. We identified a gradient of relative effects of plant and microbial traits from properties controlled mostly by aboveground processes, such as plant biomass production and standing litter, to properties controlled mostly by microbial processes, such as soil leaching of

  9. Grazing-induced losses of biodiversity affect the transpiration of an arid ecosystem.

    PubMed

    Verón, Santiago R; Paruelo, José M; Oesterheld, Martín

    2011-02-01

    Degradation processes often lead to species loss. Such losses would impact on ecosystem functioning depending on the extinction order and the functional and structural aspects of species. For the Patagonian arid steppe, we used a simulation model to study the effects of species loss on the rate and variability (i.e. stability) of transpiration as a key attribute of ecosystem functioning. We addressed (1) the differences between the overgrazing extinction order and other potential orders, and (2) the role of biomass abundance, biomass distribution, and functional diversity on the effect of species loss due to overgrazing. We considered a community composed of ten species which were assigned an order of extinction due to overgrazing based on their preference by livestock. We performed four model simulations to test for overgrazing effects through different combinations of species loss, and reductions of biomass and functional diversity. In general, transpiration rate and variability were positively associated to species richness and remained fairly constant until half the species were lost by overgrazing. The extinction order by overgrazing was the most conservative of all possible orders. The amount of biomass was more important than functional diversity in accounting for the impacts of species richness on transpiration. Our results suggest that, to prevent Patagonian steppes from shifting to stable, low-production systems (by overgrazing), maintaining community biomass is more important than preserving species richness or species functional diversity. PMID:20865282

  10. Calibration of two complex ecosystem models with different likelihood functions

    NASA Astrophysics Data System (ADS)

    Hidy, Dóra; Haszpra, László; Pintér, Krisztina; Nagy, Zoltán; Barcza, Zoltán

    2014-05-01

    The biosphere is a sensitive carbon reservoir. Terrestrial ecosystems were approximately carbon neutral during the past centuries, but they became net carbon sinks due to climate change induced environmental change and associated CO2 fertilization effect of the atmosphere. Model studies and measurements indicate that the biospheric carbon sink can saturate in the future due to ongoing climate change which can act as a positive feedback. Robustness of carbon cycle models is a key issue when trying to choose the appropriate model for decision support. The input parameters of the process-based models are decisive regarding the model output. At the same time there are several input parameters for which accurate values are hard to obtain directly from experiments or no local measurements are available. Due to the uncertainty associated with the unknown model parameters significant bias can be experienced if the model is used to simulate the carbon and nitrogen cycle components of different ecosystems. In order to improve model performance the unknown model parameters has to be estimated. We developed a multi-objective, two-step calibration method based on Bayesian approach in order to estimate the unknown parameters of PaSim and Biome-BGC models. Biome-BGC and PaSim are a widely used biogeochemical models that simulate the storage and flux of water, carbon, and nitrogen between the ecosystem and the atmosphere, and within the components of the terrestrial ecosystems (in this research the developed version of Biome-BGC is used which is referred as BBGC MuSo). Both models were calibrated regardless the simulated processes and type of model parameters. The calibration procedure is based on the comparison of measured data with simulated results via calculating a likelihood function (degree of goodness-of-fit between simulated and measured data). In our research different likelihood function formulations were used in order to examine the effect of the different model

  11. Biophysical interactions in fluvial ecosystems: effects of submerged aquatic macrophytes on hydro-morphological processes and ecosystem functioning

    NASA Astrophysics Data System (ADS)

    Cornacchia, Loreta; Davies, Grieg; Grabowski, Robert; van der Wal, Daphne; van de Koppel, Johan; Wharton, Geraldene; Bouma, Tjeerd

    2016-04-01

    Strong mutual interactions occur at the interface between biota and physical processes in biogeomorphic ecosystems, possibly resulting in self-organized spatial patterns. While these interactions and feedbacks have been increasingly studied in a wide range of landscapes previously, they are still poorly understood in lower energy fluvial systems. Consequently, their impact on the functioning of aquatic ecosystems is largely unknown. In this study we investigate the role of aquatic macrophytes as biological engineers of flow and sediment in lowland streams dominated by water crowfoot (Ranunculus spp.). Using field measurements from two annual growth cycles, we demonstrate that seasonally-changing macrophyte cover maintains relative constant flow rates, both within and between vegetation, despite temporal changes in channel flow discharge. By means of a mathematical model representing the interaction between hydrodynamics and vegetation dynamics, we reveal that scale-dependent feedbacks between plant growth and flow redistribution explain the influence of macrophytes on stabilizing flow rates. Our analysis reveals important implications for ecosystem functions. The creation of fast-flowing channels allows an adequate conveyance of water throughout the annual cycle; yet, patches also have a significant influence on sediment dynamics leading to heterogeneous habitats, thereby facilitating other species. As a last step we investigate the consequences on stream ecosystem functioning, by exploring the relationship between changes in macrophyte cover and the provision of different ecosystem functions (e.g. water conveyance, sediment trapping). Our results highlight that self-organization promotes the combination of multiple ecosystem functions through its effects on hydrological and morphological processes within biogeomorphic ecosystems.

  12. [Anthropogenic EMF effects on the condition and function of natural ecosystems].

    PubMed

    Grigor'ev, O A; Bicheldeĭ, E P; Merkulo v, A V

    2003-01-01

    A review of Russian and foreign studies of EMF effects on living environment was made. Vast range of EMF frequencies and intensities affect on functions and condition of ecosystems. Even non-thermal EMF levels could cause reversible changes in physiological process regulation. Some changes were observed in animal behavior such as motive activity, spatial orientation, reduction of ability to form a conditioned response. Some animal species (some insects, birds, reptiles) use electromagnetic fields for spatial orientation during migration. Biological communities are very sensitive to EMF effects and could become the biological indicators of electromagnetic pollution.

  13. Ecosystem engineering by invasive exotic beavers reduces in-stream diversity and enhances ecosystem function in Cape Horn, Chile.

    PubMed

    Anderson, Christopher B; Rosemond, Amy D

    2007-11-01

    Species invasions are of global significance, but predicting their impacts can be difficult. Introduced ecosystem engineers, however, provide an opportunity to test the underlying mechanisms that may be common to all invasive engineers and link relationships between changes in diversity and ecosystem function, thereby providing explanatory power for observed ecological patterns. Here we test specific predictions for an invasive ecosystem engineer by quantifying the impacts of habitat and resource modifications caused by North American beavers (Castor canadensis) on aquatic macroinvertebrate community structure and stream ecosystem function in the Cape Horn Biosphere Reserve, Chile. We compared responses to beavers in three habitat types: (1) forested (unimpacted) stream reaches, (2) beaver ponds, and (3) sites immediately downstream of beaver dams in four streams. We found that beaver engineering in ponds created taxonomically simplified, but more productive, benthic macroinvertebrate assemblages. Specifically, macroinvertebrate richness, diversity and number of functional feeding groups were reduced by half, while abundance, biomass and secondary production increased three- to fivefold in beaver ponds compared to forested sites. Reaches downstream of beaver ponds were very similar to natural forested sections. Beaver invasion effects on both community and ecosystem parameters occurred predominantly via increased retention of fine particulate organic matter, which was associated with reduced macroinvertebrate richness and diversity (via homogenization of benthic microhabitat) and increased macroinvertebrate biomass and production (via greater food availability). Beaver modifications to macroinvertebrate community structure were largely confined to ponds, but increased benthic production in beaver-modified habitats adds to energy retention and flow for the entire stream ecosystem. Furthermore, the effects of beavers on taxa richness (negative) and measures of

  14. On the Use of Multi-Scale Long-Term Data for Understanding Global Ecosystem Functioning

    NASA Astrophysics Data System (ADS)

    Reichstein, M.; Carvalhais, N.; Jung, M.; Mahecha, M. D.

    2014-12-01

    Recent continuous observations of this exchange of CO2, H2O and sensible heat within the global observation network FLUXNET have enabled us to quantify ecosystem function in response to large eco-climatological spatial gradients and temporal variability of climate. We see that ecosystem function co-varies strongly with climate, but that climate alone does not suffice to explain the variation in total. Instead vegetation biophysical and structural parameters co-determine the exchange of carbon, water and energy between the ecosystem and the atmosphere. By combining ecosystem level observation and information of spatial meteorological and vegetation remote sensing covariates we can infer global patterns of ecosystem atmosphere fluxes and derive key ecosystem functional properties globally. While this approach is powerful and meteorological and vegetation structural predictors explain more than 70% of the spatial variation of monthly fluxes at FLUXNET sites, it ignores the effect of ecophysiological vegetation properties, which is expected from plant physiological leaf or whole-plant studies. Hence, future research has to more strongly link the organismic trait information with ecosystem functional properties. For this we propose a framework that involves 1) the correlation of community aggregated traits with flux-derived ecosystem properties across a range of ecosystems, 2) the up-scaling of vegetation traits using spatially distributed geo-ecological co-variates and the comparison with global ecosystem functional properties and their co-variation with climate, 3) the use of vegetation traits instead of vegetation classes for empirical up-scaling of ecosystem-atmosphere fluxes from ecosystem to globe. We hypothesize that these studies will emphasize the superiority of a trait based approach over classical structural PFT concepts for modeling global ecosystem functioning, but will also highlight the scale-emergent properties at ecosystem level, which cannot be

  15. Climatic Versus Biotic Constraints on Carbon and Water Fluxes in Seasonally Drought-affected Ponderosa Pine Ecosystems. Chapter 2

    NASA Technical Reports Server (NTRS)

    Schwarz, P. A.; Law, B. E.; Williams, M.; Irvine, J.; Kurpius, M.; Moore, D.

    2005-01-01

    We investigated the relative importance of climatic versus biotic controls on gross primary production (GPP) and water vapor fluxes in seasonally drought-affected ponderosa pine forests. The study was conducted in young (YS), mature (MS), and old stands (OS) over 4 years at the AmeriFlux Metolius sites. Model simulations showed that interannual variation of GPP did not follow the same trends as precipitation, and effects of climatic variation were smallest at the OS (50%), and intermediate at the YS (<20%). In the young, developing stand, interannual variation in leaf area has larger effects on fluxes than climate, although leaf area is a function of climate in that climate can interact with age-related shifts in carbon allocation and affect whole-tree hydraulic conductance. Older forests, with well-established root systems, appear to be better buffered from effects of seasonal drought and interannual climatic variation. Interannual variation of net ecosystem exchange (NEE) was also lowest at the OS, where NEE is controlled more by interannual variation of ecosystem respiration, 70% of which is from soil, than by the variation of GPP, whereas variation in GPP is the primary reason for interannual changes in NEE at the YS and MS. Across spatially heterogeneous landscapes with high frequency of younger stands resulting from natural and anthropogenic disturbances, interannual climatic variation and change in leaf area are likely to result in large interannual variation in GPP and NEE.

  16. Direct and indirect effects of invasive plants on soil chemistry and ecosystem function.

    PubMed

    Weidenhamer, Jeffrey D; Callaway, Ragan M

    2010-01-01

    Invasive plants have a multitude of impacts on plant communities through their direct and indirect effects on soil chemistry and ecosystem function. For example, plants modify the soil environment through root exudates that affect soil structure, and mobilize and/or chelate nutrients. The long-term impact of litter and root exudates can modify soil nutrient pools, and there is evidence that invasive plant species may alter nutrient cycles differently from native species. The effects of plants on ecosystem biogeochemistry may be caused by differences in leaf tissue nutrient stoichiometry or secondary metabolites, although evidence for the importance of allelochemicals in driving these processes is lacking. Some invasive species may gain a competitive advantage through the release of compounds or combinations of compounds that are unique to the invaded community—the “novel weapons hypothesis.” Invasive plants also can exert profound impact on plant communities indirectly through the herbicides used to control them. Glyphosate, the most widely used herbicide in the world, often is used to help control invasive weeds, and generally is considered to have minimal environmental impacts. Most studies show little to no effect of glyphosate and other herbicides on soil microbial communities. However, herbicide applications can reduce or promote rhizobium nodulation and mycorrhiza formation. Herbicide drift can affect the growth of non-target plants, and glyphosate and other herbicides can impact significantly the secondary chemistry of plants at sublethal doses. In summary, the literature indicates that invasive species can alter the biogeochemistry of ecosystems, that secondary metabolites released by invasive species may play important roles in soil chemistry as well as plant-plant and plant-microbe interactions, and that the herbicides used to control invasive species can impact plant chemistry and ecosystems in ways that have yet to be fully explored.

  17. Risk assessment of nitrate and oxytetracycline addition on coastal ecosystem functions.

    PubMed

    Feng-Jiao, Liu; Shun-Xing, Li; Feng-Ying, Zheng; Xu-Guang, Huang; Yue-Gang, Zuo; Teng-Xiu, Tu; Xue-Qing, Wu

    2014-01-01

    Diatoms dominate phytoplankton communities in the well-mixed coastal and upwelling regions. Coastal diatoms are often exposed to both aquaculture pollution and eutrophication. But how these exposures influence on coastal ecosystem functions are unknown. To examine these influences, a coastal centric diatom, Conticribra weissflogii was maintained at different concentrations of nitrate (N) and/or oxytetracycline (OTC). Algal density, cell growth cycle, protein, chlorophyll a, superoxide dismutase (SOD) activity, and malonaldehyde (MDA) were determined for the assessment of algal biomass, lifetime, nutritional value, photosynthesis and respiration, antioxidant capacity, and lipid peroxidation, respectively. When N addition was combined with OTC pollution, the cell growth cycles were shortened by 56-73%; algal density, SOD activities, the concentrations of chlorophyll a, protein, and MDA varied between 73 and 121%, 19 and 397%, 52 and 693%, 19 and 875%, and 66 and 2733% of the values observed in N addition experiments, respectively. According to P-value analysis, the influence of OTC on algal density and SOD activity was not significant, but the effect on cell growth cycle, protein, chlorophyll a, and MDA were significant (P<0.05). The influence of N addition with simultaneous OTC pollution on the above six end points was significant. Algal biomass, lifetime, nutrition, antioxidant capacity, lipid peroxidation, photosynthesis, and respiration were all affected by the addition of OTC and N. Coastal ecosystem functions were severely affected by N and OTC additions, and the influence was increased in the order: Necosystem functions.

  18. Climate change drives a shift in peatland ecosystem plant community: implications for ecosystem function and stability.

    PubMed

    Dieleman, Catherine M; Branfireun, Brian A; McLaughlin, James W; Lindo, Zoë

    2015-01-01

    The composition of a peatland plant community has considerable effect on a range of ecosystem functions. Peatland plant community structure is predicted to change under future climate change, making the quantification of the direction and magnitude of this change a research priority. We subjected intact, replicated vegetated poor fen peat monoliths to elevated temperatures, increased atmospheric carbon dioxide (CO2 ), and two water table levels in a factorial design to determine the individual and synergistic effects of climate change factors on the poor fen plant community composition. We identify three indicators of a regime shift occurring in our experimental poor fen system under climate change: nonlinear decline of Sphagnum at temperatures 8 °C above ambient conditions, concomitant increases in Carex spp. at temperatures 4 °C above ambient conditions suggesting a weakening of Sphagnum feedbacks on peat accumulation, and increased variance of the plant community composition and pore water pH through time. A temperature increase of +4 °C appeared to be a threshold for increased vascular plant abundance; however the magnitude of change was species dependent. Elevated temperature combined with elevated CO2 had a synergistic effect on large graminoid species abundance, with a 15 times increase as compared to control conditions. Community analyses suggested that the balance between dominant plant species was tipped from Sphagnum to a graminoid-dominated system by the combination of climate change factors. Our findings indicate that changes in peatland plant community composition are likely under future climate change conditions, with a demonstrated shift toward a dominance of graminoid species in poor fens.

  19. Science and Measurement Requirements for a Plant Physiology and Functional Types Mission: Measuring the Composition, Function and Health of Global Land and Coastal Ocean Ecosystems

    NASA Technical Reports Server (NTRS)

    Green, Robert O.; Rogez, Francois; Green, Rob; Ungar, Steve; Knox, Robert; Asner, Greg; Muller-Karger, Frank; Bissett, Paul; Chekalyuk, Alex; Dierssen, Heidi; Gamon, John; Hook, Simon; Meister, Gerhard; Middleton, Betsy; Ollinger, Scott; Roberts, Dar; Siegel, Dave; Townsend, Phil; Saatchi, Sassan; Unstin, Susan; Turner, Woody; Wickland, Diane; Bontempi, Paula; Emanuel, Bill

    2007-01-01

    This slide presentation reviews the proposed Plant Physiology and Functional Types (PPFT) Mission. The National Academy of Sciences Decadal Survey, placed a critical priority on a Mission to observe distribution and changes in ecosystem functions. The PPFT satellite mission provides the essential measurements needed to assess drivers of change in biodiversity and ecosystem services that affect human welfare. The presentation reviews the science questions that the mission will be designed to answer, the science rationale, the science measurements, the mission concept, the planned instrumentation, the calibration method, and key signal to noise ratios and uniformity requirements.

  20. Impacts of drought and crayfish invasion on stream ecosystem structure and function

    USGS Publications Warehouse

    Magoulick, Daniel D.

    2014-01-01

    Drought and seasonal drying can be important disturbance events in many small streams, leading to intermittent or isolated habitats. Many small streams contain crayfish populations that are often keystone or dominant species in these systems. I conducted an experiment in stream mesocosms to examine the effects of drought and potential ecological redundancy of a native and invasive crayfish species. I examined the effects of drought (drought or control) and crayfish presence (none, native crayfish Orconectes eupunctus or invasive crayfish Orconectes neglectus) on stream mesocosm structure and function (leaf breakdown, community metabolism, periphyton, sediment and chironomid densities) in a fully factorial design. Each mesocosm contained a deep and shallow section, and drought treatments had surface water present (5-cm depth) in deep sections where tiles and leaf packs were placed. Drought and crayfish presence did not interact for any response variable. Drought significantly reduced leaf breakdown, and crayfish presence significantly increased leaf breakdown. However, the native and invasive crayfish species did not differ significantly in their effects on leaf breakdown. Drought significantly reduced primary production and community respiration overall, whereas crayfish presence did not significantly affect primary production and community respiration. Neither drought nor crayfish presence significantly affected periphyton overall. However, drought significantly reduced autotrophic index (AI), and crayfish presence increased AI. Inorganic sediment and chironomid density were not affected by drought, but both were significantly reduced by crayfish presence. O. eupunctus reduced AI and sediment more than O. neglectus did. Neither drought nor crayfish species significantly affected crayfish growth or survival. Drought can have strong effects on ecosystem function, but weaker effects on benthic structure. Crayfish can have strong effects on ecosystem

  1. Arctic ecosystem structure and functioning shaped by climate and herbivore body size

    NASA Astrophysics Data System (ADS)

    Legagneux, P.; Gauthier, G.; Lecomte, N.; Schmidt, N. M.; Reid, D.; Cadieux, M.-C.; Berteaux, D.; Bêty, J.; Krebs, C. J.; Ims, R. A.; Yoccoz, N. G.; Morrison, R. I. G.; Leroux, S. J.; Loreau, M.; Gravel, D.

    2014-05-01

    Significant progress has been made in our understanding of species-level responses to climate change, but upscaling to entire ecosystems remains a challenge. This task is particularly urgent in the Arctic, where global warming is most pronounced. Here we report the results of an international collaboration on the direct and indirect effects of climate on the functioning of Arctic terrestrial ecosystems. Our data from seven terrestrial food webs spread along a wide range of latitudes (~1,500 km) and climates (Δ mean July temperature = 8.5 °C) across the circumpolar world show the effects of climate on tundra primary production, food-web structure and species interaction strength. The intensity of predation on lower trophic levels increased significantly with temperature, at approximately 4.5% per °C. Temperature also affected trophic interactions through an indirect effect on food-web structure (that is, diversity and number of interactions). Herbivore body size was a major determinant of predator-prey interactions, as interaction strength was positively related to the predator-prey size ratio, with large herbivores mostly escaping predation. There is potential for climate warming to cause a switch from bottom-up to top-down regulation of herbivores. These results are critical to resolving the debate on the regulation of tundra and other terrestrial ecosystems exposed to global change.

  2. Ecosystem services: developing sustainable management paradigms based on wetland functions and processes

    USGS Publications Warehouse

    Euliss, Ned H.; Mushet, David M.; Smith, Loren M.; Conner, William H.; Burkett, Virginia R.; Wilcox, Douglas A.; Hester, Mark W.; Zheng, Haochi

    2013-01-01

    findings. In comparison to older and more traditional scientific disciplines, the wetland sciences may be better equipped to tackle today’s complex problems. Since its emergence as a scientific discipline, the study of wetlands has frequently required interdisciplinary and integrated approaches. This interdisciplinary/integrated approach is largely the result of the fact that wetlands cannot be studied in isolation of upland areas that contribute surface and subsurface water, solutes, sediments, and nutrients into wetland basins. However, challenges still remain in thoroughly integrating the wetland sciences with scientific disciplines involved in upland studies, especially those involved with agriculture, development, and other land-conversion activities that influence wetland hydrology, chemistry, and sedimentation. One way to facilitate this integration is to develop an understanding of how human activities affect wetland ecosystem services, especially the trade-offs and synergisms that occur when land-use changes are made. Used in this context, an understanding of the real costs of managing for a particular ecosystem service or groups of services can be determined and quantified in terms of reduced delivery of other services and in overall sustainability of the wetland and the landscapes that support them. In this chapter, we discuss some of the more salient aspects of a few common wetland types to give the reader some background on the diversity of functions that wetlands perform and the specific ecosystem services they provide to society. Wetlands are among the most complex ecosystems on the planet, and it is often difficult to communicate to a diverse public all of the positive services wetlands provide to mankind. Our goal is to help the reader develop an understanding that management options can be approached as societal choices where decisions can be made within a spatial and temporal context to identify trade-offs, synergies, and effects on long

  3. Can human health outcomes be used as bioindicators of ecosystem function?

    PubMed

    Weinstein, Philip

    2010-02-01

    Bioindicators of ecosystem health, such as ant (Hymenoptera: Formicidae) diversity, reflect the ultimate (evolutionary) drivers of ecosystem function. Surveillance data on human population health, such as the frequency of ant stings, also provide a useful bioindicator of ecosystem health in so far as the presence of imported, stinging, pest species reflects the proximate (mechanistic) drivers of ecosystem function. The relationship between human health surveillance data and the ultimate drivers of ecosystem function has however not been studied at a research level. The possible integrated use of such apparently disparate data may offer a new tool to help manage our environment sustainably for the concurrent benefit of both ecosystem health and human health. Productive directions for research in this field are likely to lie in areas where disease outcomes are dependent on environmental intermediaries, such as vector borne or water borne infectious diseases, and the paper provides one worked example using allergy to ant stings as a case study.

  4. Nematomorph parasites indirectly alter the food web and ecosystem function of streams through behavioural manipulation of their cricket hosts.

    USGS Publications Warehouse

    Sato, T.; Egusa, T.; Fukushima, K.; Oda, T.; Ohte, N.; Tokuchi, Naoko; Watanabe, Katsutoshi; Kanaiwa, Minoru; Murakami, Isaya; Lafferty, Kevin D.

    2012-01-01

    Nematomorph parasites manipulate crickets to enter streams where the parasites reproduce. These manipulated crickets become a substantial food subsidy for stream fishes. We used a field experiment to investigate how this subsidy affects the stream community and ecosystem function. When crickets were available, predatory fish ate fewer benthic invertebrates. The resulting release of the benthic invertebrate community from fish predation indirectly decreased the biomass of benthic algae and slightly increased leaf break-down rate. This is the first experimental demonstration that host manipulation by a parasite can reorganise a community and alter ecosystem function. Nematomorphs are common, and many other parasites have dramatic effects on host phenotypes, suggesting that similar effects of parasites on ecosystems might be widespread.

  5. Assessing the transferability of ecosystem service production estimates and functions

    EPA Science Inventory

    Estimates of ecosystem service (ES) production, and their responses to stressors or policy actions, may be obtained by direct measurement, other empirical studies, or modeling. Direct measurement is costly and often impractical, and thus many studies transfer ES production estim...

  6. [Assessment on the changing conditions of ecosystems in key ecological function zones in China].

    PubMed

    Huang, Lin; Cao, Wei; Wu, Dan; Gong, Guo-li; Zhao, Guo-song

    2015-09-01

    In this paper, the dynamics of ecosystem macrostructure, qualities and core services during 2000 and 2010 were analyzed for the key ecological function zones of China, which were classified into four types of water conservation, soil conservation, wind prevention and sand fixation, and biodiversity maintenance. In the water conservation ecological function zones, the areas of forest and grassland ecosystems were decreased whereas water bodies and wetland were increased in the past 11 years, and the water conservation volume of forest, grassland and wetland ecosystems increased by 2.9%. This region needs to reverse the decreasing trends of forest and grassland ecosystems. In the soil conservation ecological function zones, the area of farmland ecosystem was decreased, and the areas of forest, grassland, water bodies and wetland ecosystems were increased. The total amount of the soil erosion was reduced by 28.2%, however, the soil conservation amount of ecosystems increased by 38.1%. In the wind prevention and sand fixation ecological function zones, the areas of grassland, water bodies and wetland ecosystems were decreased, but forest and farmland ecosystems were increased. The unit amount of the soil. wind erosion was reduced and the sand fixation amount of ecosystems increased lightly. In this kind of region that is located in arid and semiarid areas, ecological conservation needs to reduce farmland area and give priority to the protection of the original ecological system. In the biodiversity maintenance ecological function zones, the areas of grassland and desert ecosystems were decreased and other types were increased. The human disturbances showed a weakly upward trend and needs to be reduced. The key ecological function zones should be aimed at the core services and the protecting objects, to assess quantitatively on the effectiveness of ecosystem conservation and improvement.

  7. Functional diversity enhances the resistance of ecosystem multifunctionality to aridity in Mediterranean drylands

    PubMed Central

    Valencia-Gómez, Enrique; Maestre, Fernando T.; Le Bagousse-Pinguet, Yoann; Quero, José Luis; Tamme, Riin; Börger, Luca; García-Gómez, Miguel; Gross, Nicolas

    2015-01-01

    SUMMARY We used a functional trait-based approach to assess the impacts of aridity and shrub encroachment on the functional structure of Mediterranean dryland communities (functional diversity and community-weighted mean trait values [CWM]), and to evaluate how these functional attributes ultimately affect multifunctionality (i.e., the provision of several ecosystem functions simultaneously). Shrub encroachment (the increase in the abundance/cover of shrubs) is a major land cover change that is taking place in grasslands worldwide. Studies conducted on drylands have reported positive or negative impacts of shrub encroachment depending on the functions and the traits of the sprouting or non-sprouting shrub species considered. Functional diversity and CWM were equally important as drivers of multifunctionality responses to both aridity and shrub encroachment. Size traits (e.g., vegetative height or lateral spread) and leaf traits (e.g., specific leaf area and leaf dry matter content) captured the effect of shrub encroachment on multifunctionality with a relative high accuracy (r2=0.63). Functional diversity also improved the resistance of multifunctionality along the aridity gradient studied. Maintaining and enhancing functional diversity in plant communities may help to buffer negative effects of ongoing global environmental change on dryland multifunctionality. PMID:25615801

  8. Fish foraging patterns, vulnerability to fishing, and implications for the management of ecosystem function across scales.

    PubMed

    Nash, Kirsty L; Graham, Nicholas A J; Bellwood, David R

    2013-10-01

    The function of species has been recognized as critical for the maintenance of ecosystems within desired states. However, there are still considerable gaps in our knowledge of interspecific differences in the functional roles of organisms, particularly with regard to the spatial scales over which functional impact is exerted. This has implications for the delivery of function and the maintenance of ecosystem processes. In this study we assessed the allometric relationship between foraging movements and fish body length at three sites, for 20 species of herbivorous reef fishes within four different functional groups: browsers, farmers, grazer/ detritivores, and scraper/excavators. The relationship between vulnerability of species to fishing and their scale of foraging was also examined. We present empirical evidence of the strong, positive, log-linear relationship between the scale of foraging movement and fish body length. This relationship was consistent among sites and between the two different movement metrics used. Phylogeny did not affect these results. Functional groups foraged over contrasting ranges of spatial scales; for example, scraper/excavators performed their role over a wide range of scales, whereas browsers were represented by few species and operated over a narrow range of scales. Overfishing is likely not only to remove species operating at large scales, but also to remove the browser group as a whole. Large fishes typically have a significant role in removing algae on reefs, and browsers are key to controlling macroalgae and reversing shifts to macroalgal-dominated states. This vulnerability to exploitation has serious consequences for the ability of fish assemblages to deliver their functional role in the face of anthropogenic impacts. However, identification of the scales at which herbivorous fish assemblages are susceptible to fishing provides managers with critical knowledge to design management strategies to support coral-dominated reefs by

  9. Fish foraging patterns, vulnerability to fishing, and implications for the management of ecosystem function across scales.

    PubMed

    Nash, Kirsty L; Graham, Nicholas A J; Bellwood, David R

    2013-10-01

    The function of species has been recognized as critical for the maintenance of ecosystems within desired states. However, there are still considerable gaps in our knowledge of interspecific differences in the functional roles of organisms, particularly with regard to the spatial scales over which functional impact is exerted. This has implications for the delivery of function and the maintenance of ecosystem processes. In this study we assessed the allometric relationship between foraging movements and fish body length at three sites, for 20 species of herbivorous reef fishes within four different functional groups: browsers, farmers, grazer/ detritivores, and scraper/excavators. The relationship between vulnerability of species to fishing and their scale of foraging was also examined. We present empirical evidence of the strong, positive, log-linear relationship between the scale of foraging movement and fish body length. This relationship was consistent among sites and between the two different movement metrics used. Phylogeny did not affect these results. Functional groups foraged over contrasting ranges of spatial scales; for example, scraper/excavators performed their role over a wide range of scales, whereas browsers were represented by few species and operated over a narrow range of scales. Overfishing is likely not only to remove species operating at large scales, but also to remove the browser group as a whole. Large fishes typically have a significant role in removing algae on reefs, and browsers are key to controlling macroalgae and reversing shifts to macroalgal-dominated states. This vulnerability to exploitation has serious consequences for the ability of fish assemblages to deliver their functional role in the face of anthropogenic impacts. However, identification of the scales at which herbivorous fish assemblages are susceptible to fishing provides managers with critical knowledge to design management strategies to support coral-dominated reefs by

  10. Global climate change and the evolutionary ecology of ecosystem functioning.

    PubMed

    Schmitz, Oswald J

    2013-09-01

    Environmental warming due to global climate change is an important stressor that stands to alter organismal physiology and, ultimately, carbon cycling in ecosystems. Yet the theoretical framework for predicting warming effects on whole-ecosystem carbon balance by way of changes in organismal physiology remains rudimentary. This is because ecosystem science has yet to embrace principles of evolutionary ecology that offer the means to explain how environmental stress on organisms mediates ecosystem carbon dynamics. Here, using selected case studies and a theoretical model, I sketch out one framework that shows how increases in animal metabolic rates in response to thermal stress lead to phenotypically plastic shifts in animal elemental demand, from nitrogen-rich proteins that support production to carbon-rich soluble carbohydrates that support elevated energy demands. I further show how such a switch in resource selection alters the fate of carbon between atmospheric versus animal, plant, and soil pools. The framework shows that animals, despite having relatively low biomass representation in ecosystems, can nonetheless have disproportionately larger effects on carbon cycling in ecosystems whose effects are exacerbated by environmental stressors like climate warming.

  11. Soil ecosystem functioning under climate change: plant species and community effects

    SciTech Connect

    Kardol, Paul; Cregger, Melissa; Campany, Courtney E; Classen, Aimee T

    2010-01-01

    Feedbacks of terrestrial ecosystems to climate change depend on soil ecosystem dynamics. Soil ecosystems can directly and indirectly respond to climate change. For example, warming directly alters microbial communities by increasing their activity. Climate change may also alter plant community composition, thus indirectly altering the microbial communities that feed on their inputs. To better understand how climate change may directly and indirectly alter soil ecosystem functioning, we investigated old-field plant community and soil ecosystem responses to single and combined effects of elevated [CO2], warming, and water availability. Specifically, we collected soils at the plot level (plant community soils), and beneath dominant plant species (plant-specific soils). We used microbial enzyme activities and soil nematodes as indicators for soil ecosystem functioning. Our study resulted in two main findings: 1) Overall, while there were some interactions, water, relative to increases in [CO2] and warming, had the largest impact on plant community composition, soil enzyme activities, and soil nematodes. Multiple climate change factors can interact to shape ecosystems, but in this case, those interactions were largely driven by changes in water availability. 2) Indirect effects of climate change, via changes in plant communities, had a significant impact on soil ecosystem functioning and this impact was not obvious when looking at plant community soils. Climate change effects on enzyme activities and soil nematode abundance and community structure strongly differed between plant community soils and plant-specific soils, but also within plant-specific soils. In sum, these results indicate that accurate assessments of climate change impacts on soil ecosystem functioning require incorporating the concurrent changes in plant function and plant community composition. Climate change-induced shifts in plant community composition will likely modify or counteract the direct

  12. Soil ecosystem functioning under climate change: plant species and community effects.

    PubMed

    Kardol, Paul; Cregger, Melissa A; Campany, Courtney E; Classen, Aimee T

    2010-03-01

    Feedbacks of terrestrial ecosystems to atmospheric and climate change depend on soil ecosystem dynamics. Soil ecosystems can directly and indirectly respond to climate change. For example, warming directly alters microbial communities by increasing their activity. Climate change may also alter plant community composition, thus indirectly altering the soil communities that depend on their inputs. To better understand how climate change may directly and indirectly alter soil ecosystem functioning, we investigated old-field plant community and soil ecosystem responses to single and combined effects of elevated [CO2], warming, and precipitation in Tennessee (USA). Specifically, we collected soils at the plot level (plant community soils) and beneath dominant plant species (plant-specific soils). We used microbial enzyme activities and soil nematodes as indicators for soil ecosystem functioning. Our study resulted in two main findings: (1) Overall, while there were some interactions, water, relative to increases in [CO2] and warming, had the largest impact on plant community composition, soil enzyme activity, and soil nematodes. Multiple climate-change factors can interact to shape ecosystems, but in our study, those interactions were largely driven by changes in water. (2) Indirect effects of climate change, via changes in plant communities, had a significant impact on soil ecosystem functioning, and this impact was not obvious when looking at plant community soils. Climate-change effects on enzyme activities and soil nematode abundance and community structure strongly differed between plant community soils and plant-specific soils, but also within plant-specific soils. These results indicate that accurate assessments of climate-change impacts on soil ecosystem functioning require incorporating the concurrent changes in plant function and plant community composition. Climate-change-induced shifts in plant community composition will likely modify or counteract the

  13. Functional composition drives ecosystem function through multiple mechanisms in a broadleaved subtropical forest.

    PubMed

    Chiang, Jyh-Min; Spasojevic, Marko J; Muller-Landau, Helene C; Sun, I-Fang; Lin, Yiching; Su, Sheng-Hsin; Chen, Zueng-Sang; Chen, Chien-Teh; Swenson, Nathan G; McEwan, Ryan W

    2016-11-01

    Understanding the role of biodiversity (B) in maintaining ecosystem function (EF) is a foundational scientific goal with applications for resource management and conservation. Two main hypotheses have emerged that address B-EF relationships: niche complementarity (NC) and the mass-ratio (MR) effect. We tested the relative importance of these hypotheses in a subtropical old-growth forest on the island nation of Taiwan for two EFs: aboveground biomass (ABG) and coarse woody productivity (CWP). Functional dispersion (FDis) of eight plant functional traits was used to evaluate complementarity of resource use. Under the NC hypothesis, EF will be positively correlated with FDis. Under the MR hypothesis, EF will be negatively correlated with FDis and will be significantly influenced by community-weighted mean (CWM) trait values. We used path analysis to assess how these two processes (NC and MR) directly influence EF and may contribute indirectly to EF via their influence on canopy packing (stem density). Our results indicate that decreasing functional diversity and a significant influence of CWM traits were linked to increasing AGB for all eight traits in this forest supporting the MR hypothesis. Interestingly, CWP was primarily influenced by NC and MR indirectly via their influence on canopy packing. Maximum height explained more of the variation in both AGB and CWP than any of the other plant functional traits. Together, our results suggest that multiple mechanisms operate simultaneously to influence EF, and understanding their relative importance will help to elucidate the role of biodiversity in maintaining ecosystem function. PMID:27632194

  14. Glyphosate herbicide affects belowground interactions between earthworms and symbiotic mycorrhizal fungi in a model ecosystem

    PubMed Central

    Zaller, Johann G.; Heigl, Florian; Ruess, Liliane; Grabmaier, Andrea

    2014-01-01

    Herbicides containing glyphosate are widely used in agriculture and private gardens, however, surprisingly little is known on potential side effects on non-target soil organisms. In a greenhouse experiment with white clover we investigated, to what extent a globally-used glyphosate herbicide affects interactions between essential soil organisms such as earthworms and arbuscular mycorrhizal fungi (AMF). We found that herbicides significantly decreased root mycorrhization, soil AMF spore biomass, vesicles and propagules. Herbicide application and earthworms increased soil hyphal biomass and tended to reduce soil water infiltration after a simulated heavy rainfall. Herbicide application in interaction with AMF led to slightly heavier but less active earthworms. Leaching of glyphosate after a simulated rainfall was substantial and altered by earthworms and AMF. These sizeable changes provide impetus for more general attention to side-effects of glyphosate-based herbicides on key soil organisms and their associated ecosystem services. PMID:25005713

  15. Glyphosate herbicide affects belowground interactions between earthworms and symbiotic mycorrhizal fungi in a model ecosystem

    NASA Astrophysics Data System (ADS)

    Zaller, Johann G.; Heigl, Florian; Ruess, Liliane; Grabmaier, Andrea

    2014-07-01

    Herbicides containing glyphosate are widely used in agriculture and private gardens, however, surprisingly little is known on potential side effects on non-target soil organisms. In a greenhouse experiment with white clover we investigated, to what extent a globally-used glyphosate herbicide affects interactions between essential soil organisms such as earthworms and arbuscular mycorrhizal fungi (AMF). We found that herbicides significantly decreased root mycorrhization, soil AMF spore biomass, vesicles and propagules. Herbicide application and earthworms increased soil hyphal biomass and tended to reduce soil water infiltration after a simulated heavy rainfall. Herbicide application in interaction with AMF led to slightly heavier but less active earthworms. Leaching of glyphosate after a simulated rainfall was substantial and altered by earthworms and AMF. These sizeable changes provide impetus for more general attention to side-effects of glyphosate-based herbicides on key soil organisms and their associated ecosystem services.

  16. Glyphosate herbicide affects belowground interactions between earthworms and symbiotic mycorrhizal fungi in a model ecosystem.

    PubMed

    Zaller, Johann G; Heigl, Florian; Ruess, Liliane; Grabmaier, Andrea

    2014-07-09

    Herbicides containing glyphosate are widely used in agriculture and private gardens, however, surprisingly little is known on potential side effects on non-target soil organisms. In a greenhouse experiment with white clover we investigated, to what extent a globally-used glyphosate herbicide affects interactions between essential soil organisms such as earthworms and arbuscular mycorrhizal fungi (AMF). We found that herbicides significantly decreased root mycorrhization, soil AMF spore biomass, vesicles and propagules. Herbicide application and earthworms increased soil hyphal biomass and tended to reduce soil water infiltration after a simulated heavy rainfall. Herbicide application in interaction with AMF led to slightly heavier but less active earthworms. Leaching of glyphosate after a simulated rainfall was substantial and altered by earthworms and AMF. These sizeable changes provide impetus for more general attention to side-effects of glyphosate-based herbicides on key soil organisms and their associated ecosystem services.

  17. Occurrence of perchloroethylene in surface water and fish in a river ecosystem affected by groundwater contamination.

    PubMed

    Wittlingerová, Zdena; Macháčková, Jiřina; Petruželková, Anna; Zimová, Magdalena

    2016-03-01

    Long-term monitoring of the content of perchloroethylene (PCE) in a river ecosystem affected by groundwater contamination was performed at a site in the Czech Republic. The quality of surface water was monitored quarterly between 1994 and 2013, and fish were collected from the affected ecosystem to analyse the content of PCE in their tissue in 1998, 2011 and 2012. Concentrations of PCE (9-140 μg/kg) in the tissue of fish collected from the contaminated part of the river were elevated compared to the part of the river unaffected by the contamination (ND to 5 μg/kg PCE). The quality of surface water has improved as a result of groundwater remediation during the evaluated period. Before the remedial action, PCE concentrations ranged from 30 to 95 μg/L (1994-1997). Following commencement of remedial activities in September 1997, a decrease in the content of PCE in the surface water to 7.3 μg/L (1998) and further to 1 μg/L (2011) and 1.1 μg/L (2012) led to a progressive decrease in the average concentration of PCE in the fish muscle tissue from 79 μg/kg (1998) to 24 (2011) and 30 μg/kg (2012), respectively. It was determined that the bioconcentration of PCE does not have a linear dependence because the decrease in contamination in the fish muscle tissue is not directly proportional to the decrease in contamination in the river water. The observed average bioconcentration factors were 24 and 28 for the lower concentrations of PCE and 11 for the higher concentrations of PCE in the river. In terms of age, length and weight of the collected fish, weight had the greatest significance for bioconcentration, followed by the length, with age being evaluated as a less significant factor.

  18. Diversity, functional similarity, and top-down control drive synchronization and the reliability of ecosystem function.

    PubMed

    Bauer, Barbara; Vos, Matthijs; Klauschies, Toni; Gaedke, Ursula

    2014-03-01

    The concept that diversity promotes reliability of ecosystem function depends on the pattern that community-level biomass shows lower temporal variability than species-level biomasses. However, this pattern is not universal, as it relies on compensatory or independent species dynamics. When in contrast within-trophic level synchronization occurs, variability of community biomass will approach population-level variability. Current knowledge fails to integrate how species richness, functional distance between species, and the relative importance of predation and competition combine to drive synchronization at different trophic levels. Here we clarify these mechanisms. Intense competition promotes compensatory dynamics in prey, but predators may at the same time increasingly synchronize, under increasing species richness and functional similarity. In contrast, predators and prey both show perfect synchronization under strong top-down control, which is promoted by a combination of low functional distance and high net growth potential of predators. Under such conditions, community-level biomass variability peaks, with major negative consequences for reliability of ecosystem function. PMID:24561602

  19. The functional value of Caribbean coral reef, seagrass and mangrove habitats to ecosystem processes.

    PubMed

    Harborne, Alastair R; Mumby, Peter J; Micheli, Fiorenza; Perry, Christopher T; Dahlgren, Craig P; Holmes, Katherine E; Brumbaugh, Daniel R

    2006-01-01

    Caribbean coral reef habitats, seagrass beds and mangroves provide important goods and services both individually and through functional linkages. A range of anthropogenic factors are threatening the ecological and economic importance of these habitats and it is vital to understand how ecosystem processes vary across seascapes. A greater understanding of processes will facilitate further insight into the effects of disturbances and assist with assessing management options. Despite the need to study processes across whole seascapes, few spatially explicit ecosystem-scale assessments exist. We review the empirical literature to examine the role of different habitat types for a range of processes. The importance of each of 10 generic habitats to each process is defined as its "functional value" (none, low, medium or high), quantitatively derived from published data wherever possible and summarised in a single figure. This summary represents the first time the importance of habitats across an entire Caribbean seascape has been assessed for a range of processes. Furthermore, we review the susceptibility of each habitat to disturbances to investigate spatial patterns that might affect functional values. Habitat types are considered at the scale discriminated by remotely-sensed imagery and we envisage that functional values can be combined with habitat maps to provide spatially explicit information on processes across ecosystems. We provide examples of mapping the functional values of habitats for populations of three commercially important species. The resulting data layers were then used to generate seascape-scale assessments of "hot spots" of functional value that might be considered priorities for conservation. We also provide an example of how the literature reviewed here can be used to parameterise a habitat-specific model investigating reef resilience under different scenarios of herbivory. Finally, we use multidimensional scaling to provide a basic analysis of the

  20. Ecosystem function decays by fungal outbreaks in Antarctic microbial mats

    PubMed Central

    Velázquez, David; López-Bueno, Alberto; Aguirre de Cárcer, Daniel; de los Ríos, Asunción; Alcamí, Antonio; Quesada, Antonio

    2016-01-01

    Antarctica harbours a remarkably diverse range of freshwater bodies and terrestrial ecosystems, where microbial mats are considered the most important systems in terms of biomass and metabolic capabilities. We describe the presence of lysis plaque-like macroscopic blighted patches within the predominant microbial mats on Livingston Island (Antarctic Peninsula). Those blighting circles are associated with decay in physiological traits as well as nitrogen depletion and changes in the spatial microstructure; these alterations were likely related to disruption of the biogeochemical gradients within the microbial ecosystem caused by an unusually high fungal abundance and consequent physical alterations. This phenomenon has been evidenced at a time of unprecedented rates of local warming in the Antarctic Peninsula area, and decay of these ecosystems is potentially stimulated by warmer temperatures. PMID:26972923

  1. Ecosystem function decays by fungal outbreaks in Antarctic microbial mats.

    PubMed

    Velázquez, David; López-Bueno, Alberto; Aguirre de Cárcer, Daniel; de los Ríos, Asunción; Alcamí, Antonio; Quesada, Antonio

    2016-03-14

    Antarctica harbours a remarkably diverse range of freshwater bodies and terrestrial ecosystems, where microbial mats are considered the most important systems in terms of biomass and metabolic capabilities. We describe the presence of lysis plaque-like macroscopic blighted patches within the predominant microbial mats on Livingston Island (Antarctic Peninsula). Those blighting circles are associated with decay in physiological traits as well as nitrogen depletion and changes in the spatial microstructure; these alterations were likely related to disruption of the biogeochemical gradients within the microbial ecosystem caused by an unusually high fungal abundance and consequent physical alterations. This phenomenon has been evidenced at a time of unprecedented rates of local warming in the Antarctic Peninsula area, and decay of these ecosystems is potentially stimulated by warmer temperatures.

  2. The influence of balanced and imbalanced resource supply on biodiversity-functioning relationship across ecosystems.

    PubMed

    Lewandowska, Aleksandra M; Biermann, Antje; Borer, Elizabeth T; Cebrián-Piqueras, Miguel A; Declerck, Steven A J; De Meester, Luc; Van Donk, Ellen; Gamfeldt, Lars; Gruner, Daniel S; Hagenah, Nicole; Harpole, W Stanley; Kirkman, Kevin P; Klausmeier, Christopher A; Kleyer, Michael; Knops, Johannes M H; Lemmens, Pieter; Lind, Eric M; Litchman, Elena; Mantilla-Contreras, Jasmin; Martens, Koen; Meier, Sandra; Minden, Vanessa; Moore, Joslin L; Venterink, Harry Olde; Seabloom, Eric W; Sommer, Ulrich; Striebel, Maren; Trenkamp, Anastasia; Trinogga, Juliane; Urabe, Jotaro; Vyverman, Wim; Van de Waal, Dedmer B; Widdicombe, Claire E; Hillebrand, Helmut

    2016-05-19

    Numerous studies show that increasing species richness leads to higher ecosystem productivity. This effect is often attributed to more efficient portioning of multiple resources in communities with higher numbers of competing species, indicating the role of resource supply and stoichiometry for biodiversity-ecosystem functioning relationships. Here, we merged theory on ecological stoichiometry with a framework of biodiversity-ecosystem functioning to understand how resource use transfers into primary production. We applied a structural equation model to define patterns of diversity-productivity relationships with respect to available resources. Meta-analysis was used to summarize the findings across ecosystem types ranging from aquatic ecosystems to grasslands and forests. As hypothesized, resource supply increased realized productivity and richness, but we found significant differences between ecosystems and study types. Increased richness was associated with increased productivity, although this effect was not seen in experiments. More even communities had lower productivity, indicating that biomass production is often maintained by a few dominant species, and reduced dominance generally reduced ecosystem productivity. This synthesis, which integrates observational and experimental studies in a variety of ecosystems and geographical regions, exposes common patterns and differences in biodiversity-functioning relationships, and increases the mechanistic understanding of changes in ecosystems productivity.

  3. The influence of balanced and imbalanced resource supply on biodiversity-functioning relationship across ecosystems.

    PubMed

    Lewandowska, Aleksandra M; Biermann, Antje; Borer, Elizabeth T; Cebrián-Piqueras, Miguel A; Declerck, Steven A J; De Meester, Luc; Van Donk, Ellen; Gamfeldt, Lars; Gruner, Daniel S; Hagenah, Nicole; Harpole, W Stanley; Kirkman, Kevin P; Klausmeier, Christopher A; Kleyer, Michael; Knops, Johannes M H; Lemmens, Pieter; Lind, Eric M; Litchman, Elena; Mantilla-Contreras, Jasmin; Martens, Koen; Meier, Sandra; Minden, Vanessa; Moore, Joslin L; Venterink, Harry Olde; Seabloom, Eric W; Sommer, Ulrich; Striebel, Maren; Trenkamp, Anastasia; Trinogga, Juliane; Urabe, Jotaro; Vyverman, Wim; Van de Waal, Dedmer B; Widdicombe, Claire E; Hillebrand, Helmut

    2016-05-19

    Numerous studies show that increasing species richness leads to higher ecosystem productivity. This effect is often attributed to more efficient portioning of multiple resources in communities with higher numbers of competing species, indicating the role of resource supply and stoichiometry for biodiversity-ecosystem functioning relationships. Here, we merged theory on ecological stoichiometry with a framework of biodiversity-ecosystem functioning to understand how resource use transfers into primary production. We applied a structural equation model to define patterns of diversity-productivity relationships with respect to available resources. Meta-analysis was used to summarize the findings across ecosystem types ranging from aquatic ecosystems to grasslands and forests. As hypothesized, resource supply increased realized productivity and richness, but we found significant differences between ecosystems and study types. Increased richness was associated with increased productivity, although this effect was not seen in experiments. More even communities had lower productivity, indicating that biomass production is often maintained by a few dominant species, and reduced dominance generally reduced ecosystem productivity. This synthesis, which integrates observational and experimental studies in a variety of ecosystems and geographical regions, exposes common patterns and differences in biodiversity-functioning relationships, and increases the mechanistic understanding of changes in ecosystems productivity. PMID:27114584

  4. Fighting carbon loss of degraded peatlands by jump-starting ecosystem functioning with ecological restoration.

    PubMed

    Kareksela, Santtu; Haapalehto, Tuomas; Juutinen, Riikka; Matilainen, Rose; Tahvanainen, Teemu; Kotiaho, Janne S

    2015-12-15

    Degradation of ecosystems is a great concern on the maintenance of biodiversity and ecosystem services. Ecological restoration fights degradation aiming at the recovery of ecosystem functions such as carbon (C) sequestration and ecosystem structures like plant communities responsible for the C sequestration function. We selected 38 pristine, drained and restored boreal peatland sites in Finland and asked i) what is the long-term effect of drainage on the peatland surface layer C storage, ii) can restoration recover ecosystem functioning (surface layer growth) and structure (plant community composition) and iii) is the recovery of the original structure needed for the recovery of ecosystem functions? We found that drainage had resulted in a substantial net loss of C from surface layer of drained sites. Restoration was successful in regaining natural growth rate in the peatland surface layer already within 5 years after restoration. However, the regenerated surface layer sequestered C at a mean rate of 116.3 g m(-2) yr(-1) (SE 12.7), when a comparable short-term rate was 178.2 g m(-2) yr(-1) (SE 13.3) at the pristine sites. The plant community compositions of the restored sites were considerably dissimilar to those of pristine sites still 10 years after restoration. We conclude that ecological restoration can be used to jump-start some key peatland ecosystem functions even without the recovery of original ecosystem structure (plant community composition). However, the re-establishment of other functions like C sequestration may require more profound recovery of conditions and ecosystem structure. We discuss the potential economic value of restored peatland ecosystems from the perspective of their C sequestration function.

  5. Ecosystem functional properties - useful links to organism and to global scale?

    NASA Astrophysics Data System (ADS)

    Reichstein, M.

    2015-12-01

    Classical biogeographical observations tell us that ecosystems (vegetation and soils) strongly respond to climate variation in terms of their structure and function. On the other hand the influence of vegetation function on climate via exchange of matter and energy with the atmosphere has become evident in the last decades via observational and modeling studies. Recent continuous observations of this exchange of CO2, H2O and sensible heat within the global observation network FLUXNET have enabled us to quantify ecosystem function in response to large eco-climatological spatio-temporal variability of climate. We see that ecosystem function co-varies strongly with climate, but that climate alone does not suffice to explain the variation in total. Instead vegetation biophysical and structural parameters co-determine the exchange of carbon, water and energy between the ecosystem and the atmosphere. By combining ecosystem level observation and information of spatial meteorological and vegetation remote sensing covariates we can infer global patterns of ecosystem atmosphere fluxes and derive key ecosystem functional properties globally. While this approach is powerful and meteorological and vegetation structural predictors explain more than 70% of the spatial variation of monthly fluxes at FLUXNET sites, it ignores the effect of ecophysiological vegetation properties, which is expected from plant physiological leaf or whole-plant studies. Hence, future research has to more strongly link the organismic trait information with ecosystem functional properties. For this we propose a framework that involves 1) the correlation of community aggregated traits with flux-derived ecosystem properties across a range of ecosystems, 2) the up-scaling of vegetation traits using spatially distributed geo-ecological co-variates and the comparison with global ecosystem functional properties and their co-variation with climate, 3) the use of vegetation traits instead of vegetation classes

  6. The Importance of Context in Development and Application of Ecosystem Services Production Functions

    EPA Science Inventory

    The task of estimating ecosystem service production and delivery deserves special attention. When approached as a function of land cover at any given time, context driven facets of ecosystem service production, delivery, and resulting effects on human well-being can be overlooke...

  7. [Structure and function of Fenshuijiang Reservoir ecosystem based on the analysis with Ecopath model].

    PubMed

    Wu, Zhen; Jia, Pei-Qiao; Hu, Zhong-Jun; Chen, Li-Qiao; Gu, Zhi-Min; Liu, Qi-Gen

    2012-03-01

    Based on the 2008-2009 survey data of fishery resources and eco-environment of Fenshuijiang Reservoir, a mass balance model for the Reservoir ecosystem was constructed by Ecopath with Ecosim software. The model was composed of 14 functional groups, including silver carp, bighead carp, Hemibarbus maculates, Cutler alburnus, Microlepis and other fishes, Oligochaeta, aquatic insect, zooplankton, phytoplankton, and organic detritus, etc. , being able to better simulate Fenshuijiang Reservoir ecosystem. In this ecosystem, there were five trophic levels (TLs), and the nutrient flow mainly occurred in the first three TLs. Grazing and detritus food chains were the main energy flows in the ecosystem, but the food web was simpler and susceptible to be disturbed by outer environment. The transfer efficiency at lower TLs was relatively low, indicating that the ecosystem had a lower capability in energy utilization, and the excessive stock of nutrients in the ecosystem could lead to eutrophication. The lower connectance index, system omnivory index, Finn' s cycled index, and Finn's mean path length demonstrated that the ecosystem was unstable, while the high ecosystem property indices such as Pp/R and Pp/B showed that the ecosystem was immature and highly productive. It was suggested that Fenshuijiang Reservoir was still a developing new reservoir ecosystem, with a very short history and comparatively high primary productivity.

  8. [Structure and function of Fenshuijiang Reservoir ecosystem based on the analysis with Ecopath model].

    PubMed

    Wu, Zhen; Jia, Pei-Qiao; Hu, Zhong-Jun; Chen, Li-Qiao; Gu, Zhi-Min; Liu, Qi-Gen

    2012-03-01

    Based on the 2008-2009 survey data of fishery resources and eco-environment of Fenshuijiang Reservoir, a mass balance model for the Reservoir ecosystem was constructed by Ecopath with Ecosim software. The model was composed of 14 functional groups, including silver carp, bighead carp, Hemibarbus maculates, Cutler alburnus, Microlepis and other fishes, Oligochaeta, aquatic insect, zooplankton, phytoplankton, and organic detritus, etc. , being able to better simulate Fenshuijiang Reservoir ecosystem. In this ecosystem, there were five trophic levels (TLs), and the nutrient flow mainly occurred in the first three TLs. Grazing and detritus food chains were the main energy flows in the ecosystem, but the food web was simpler and susceptible to be disturbed by outer environment. The transfer efficiency at lower TLs was relatively low, indicating that the ecosystem had a lower capability in energy utilization, and the excessive stock of nutrients in the ecosystem could lead to eutrophication. The lower connectance index, system omnivory index, Finn' s cycled index, and Finn's mean path length demonstrated that the ecosystem was unstable, while the high ecosystem property indices such as Pp/R and Pp/B showed that the ecosystem was immature and highly productive. It was suggested that Fenshuijiang Reservoir was still a developing new reservoir ecosystem, with a very short history and comparatively high primary productivity. PMID:22720630

  9. Application of macrobenthos functional groups to estimate the ecosystem health in a semi-enclosed bay.

    PubMed

    Peng, Shitao; Zhou, Ran; Qin, Xuebo; Shi, Honghua; Ding, Dewen

    2013-09-15

    In this study, the functional group concept was first applied to evaluate the ecosystem health of Bohai Bay. Macrobenthos functional groups were defined according to feeding types and divided into five groups: a carnivorous group (CA), omnivorous group (OM), planktivorous group (PL), herbivorous group (HE), and detritivorous group (DE). Groups CA, DE, OM, and PL were identified, but the HE group was absent from Bohai Bay. Group DE was dominant during the study periods. The ecosystem health was assessed using a functional group evenness index. The functional group evenness values of most sampling stations were less than 0.40, indicating that the ecosystem health was deteriorated in Bohai Bay. Such deterioration could be attributed to land reclamation, industrial and sewage effluents, oil pollution, and hypersaline water discharge. This study demonstrates that the functional group concept can be applied to ecosystem health assessment in a semi-enclosed bay.

  10. Size matters: implications of the loss of large individuals for ecosystem function.

    PubMed

    Norkko, Alf; Villnäs, Anna; Norkko, Joanna; Valanko, Sebastian; Pilditch, Conrad

    2013-01-01

    Size is a fundamental organismal trait and an important driver of ecosystem functions. Although large individuals may dominate some functions and provide important habitat structuring effects, intra-specific body size effects are rarely investigated in the context of BEF relationships. We used an in situ density manipulation experiment to explore the contribution of large, deep-burrowing bivalves to oxygen and nutrient fluxes across the sediment-water interface. By manipulating bivalve size structure through the removal of large individuals, we held species identity constant, but altered the trait characteristics of the community. The number of large bivalves was the best predictor of ecosystem functioning. Our results highlight that (a) accounting for body size provides important insights into the mechanisms underpinning biodiversity effects on ecosystem function, and (b) if local disturbances are recurrent, preventing individuals from reaching large sizes, the contribution of large adults may be lost, with largely unknown implications for ecosystem functionality.

  11. Effects of water flow regulation on ecosystem functioning in a Mediterranean river network assessed by wood decomposition.

    PubMed

    Abril, Meritxell; Muñoz, Isabel; Casas-Ruiz, Joan P; Gómez-Gener, Lluís; Barceló, Milagros; Oliva, Francesc; Menéndez, Margarita

    2015-06-01

    Mediterranean rivers are extensively modified by flow regulation practises along their courses. An important part of the river impoundment in this area is related to the presence of small dams constructed mainly for water abstraction purposes. These projects drastically modified the ecosystem morphology, transforming lotic into lentic reaches and increasing their alternation along the river. Hydro-morphologial differences between these reaches indicate that flow regulation can trigger important changes in the ecosystem functioning. Decomposition of organic matter is an integrative process and this complexity makes it a good indicator of changes in the ecosystem. The aim of this study was to assess the effect caused by flow regulation on ecosystem functioning at the river network scale, using wood decomposition as a functional indicator. We studied the mass loss from wood sticks during three months in different lotic and lentic reaches located along a Mediterranean river basin, in both winter and summer. Additionally, we identified the environmental factors affecting decomposition rates along the river orders. The results revealed differences in decomposition rates between sites in both seasons that were principally related to the differences between stream orders. The rates were mainly related to temperature, nutrient concentrations (NO2(-), NO3(2-)) and water residence time. High-order streams with higher temperature and nutrient concentrations exhibited higher decomposition rates compared with low-order streams. The effect of the flow regulation on the decomposition rates only appeared to be significant in high orders, especially in winter, when the hydrological characteristics of lotic and lentic habitats widely varied. Lotic reaches with lower water residence time exhibited greater decomposition rates compared with lentic reaches probably due to more physical abrasion and differences in the microbial assemblages. Overall, our study revealed that in high orders

  12. Ecosystem Function in Amazon Floodplain Wetlands: Climate Variability, Landscape Dynamics and Carbon Biogeochemistry.

    NASA Astrophysics Data System (ADS)

    Silva, T. S. F.; Melack, J. M.; Sousa, R. N. D.; Ferreira-Ferreira, J.; Streher, A. S.; Fragal, E. H.; Furtado, L. F.; Resende, A. F. D.; Luize, B. G.; Rudorff, C.; Queiroz, H. L.; Schongart, J.; Novo, E. M.

    2015-12-01

    Wetlands comprise 14% of the Amazon basin, and are a major component of the hydrological and biogeochemical cycles. Most of these areas correspond to floodplain ecosystems along the Amazon River and its major tributaries, hosting unique vegetation types that are strongly controlled by annual hydrological fluctuations. The combination of strong environmental filtering and active fluvial dynamics results in a highly heterogeneous landscape, and in physiological linkages between climate variability and ecosystem processes. We will show several years of results obtained within the framework of the LBA program, discussing the interplay between hydroclimatic variability, landscape dynamics, ecosystem functioning and carbon biogeochemistry in the Amazon floodplains. Using optical and microwave remote sensing, we assessed the distribution of major vegetation types and flooding regimes at several locations across the floodplain. Strong variability in vegetation distribution can be observed, with high and low várzea forests ranging from 30% and 34%, respectively, at the upper Solimões River, to 6% and 25% at the lower Solimões, while non-forested habitats and lakes increase from a percent cover of 8% and 10% to 28% and 27%, respectively. Strong variability in local flood regimes was also determined for each vegetation type, revealing a gradient of habitats within each floodplain. As tree growth, diversity and phenology are affected by flood duration, we expect local conditions to strongly impact carbon stocks and cycling at the landscape scale. Fluvial processes also disturb forest patches, ensuring a mixture of age distributions in the landscape, with varying species composition, carbon stocks, and carbon uptake rates. Herbaceous vegetation growth responds very rapidly to changes in hydrological conditions, and modeling based on microwave imagery and in situ observations showed expected changes of up to 50% in annual net primary production between regular and extreme

  13. Stable isotope views on ecosystem function: challenging or challenged?

    PubMed Central

    Resco, Víctor; Querejeta, José I.; Ogle, Kiona; Voltas, Jordi; Sebastià, Maria-Teresa; Serrano-Ortiz, Penélope; Linares, Juan C.; Moreno-Gutiérrez, Cristina; Herrero, Asier; Carreira, José A.; Torres-Cañabate, Patricia; Valladares, Fernando

    2010-01-01

    Stable isotopes and their potential for detecting various and complex ecosystem processes are attracting an increasing number of scientists. Progress is challenging, particularly under global change scenarios, but some established views have been challenged. The IX meeting of the Spanish Association of Terrestrial Ecology (AAET, Úbeda, 18–22 October 2009) hosted a symposium on the ecology of stable isotopes where the linear mixing model approach of partitioning sinks and sources of carbon and water fluxes within an ecosystem was challenged, and new applications of stable isotopes for the study of plant interactions were evaluated. Discussion was also centred on the need for networks that monitor ecological processes using stable isotopes and key ideas for fostering future research with isotopes. PMID:20015858

  14. Tracing changes in ecosystem function under elevated carbon dioxide conditions.

    SciTech Connect

    Pataki, D. E.; Ellsworth, D. S.; Evans, R. D.; Gonzalez-Meler, M.; King, J.; Leavitt, S. W.; Lin, G.; Matamala, R.; Pendall, E.; Siegwolf, R.; Van Kessel, C.; Ehleringer, J. F.; Environmental Research; Univ. of Utah; Univ. of Michigan; Washington State Univ.; Univ. of Illinois at Chicago; Michigan Technological Univ.; Univ. of Arizona; Columbia Univ.; Univ. of Wyoming; Paul Scherrer Inst.; Univ. of California, Davis

    2003-09-01

    Responses of ecosystems to elevated levels of atmospheric carbon dioxide (CO{sub 2}) remain a critical uncertainty in global change research. Two key unknown factors are the fate of carbon newly incorporated by photosynthesis into various pools within the ecosystem and the extent to which elevated CO{sub 2} is transferred to and sequestered in pools with long turnover times. The CO{sub 2} used for enrichment in many experiments incorporates a dual isotopic tracer, in the sense that ratios of both the stable carbon-13 ({sup 13}C) and the radioactive carbon-14 ({sup 14}C) isotopes with respect to carbon-12 are different from the corresponding ratios in atmospheric CO{sub 2}. Here we review techniques for using {sup 13}C and {sup 14}C abundances to follow the fate of newly fixed carbon and to further our understanding of the turnover times of ecosystem carbon pools. We also discuss the application of nitrogen, oxygen, and hydrogen isotope analyses for tracing changes in the linkages between carbon, nitrogen, and water cycles under conditions of elevated CO{sub 2}.

  15. Restoring ecosystem functions and services by overcoming soil threats - The case of Mt. Hekla area in Iceland

    NASA Astrophysics Data System (ADS)

    Thorsson, Johann; Petursdottir, Thorunn

    2015-04-01

    Soils are one of the main fundamental bodies of terrestrial ecosystems. Soil functions contribute substantially to the ecosystem services humans and all other living beings depend on. Current soil threats are in most cases related to anthropogenic impacts and derived environmental pressures. For instance, overexploitation has in many cases damaged ecosystem resilience, affected current equilibrium and caused severe soil degradation. The resulting dysfunctional ecosystems are incapable of providing necessary ecosystem services. In such cases ecosystem restoration is necessary to restore ecosystem functions and ecological succession. The Mt. Hekla area in Iceland is an example of land suffering from accelerated erosion amplified by anthropogenic impacts. The area is 900 km2 located in South Iceland in the vicinity of the volcano Mt. Hekla. Today over 40% of the area is classified as eroded but historical documents indicate that vast part of the area were fertile and vegetated at the time of settlement, 1100 years ago; hence was able to withstand the geological disturbances occurring prior to the arrival of man as is obvious from the pristine woody patches still remaining. Severe soil degradation followed the large-scale deforestation and overgrazing that took place within the area. The initial land degradation event is considered to have occurred in the 11th century, but has been ongoing since then in several episodes. The Þjórsá glacial river flows through the area and carries enormous amounts of sediments every year. After the deforestation, the ecosystem resilience was damaged and the land left exposed to the elements. Eventually large scale wind erosion started, followed with water erosion and increased impact of freeze-thaw processes. The Soil Conservation Service of Iceland started working in the area in the early 20th century and land reclamation operations have been ongoing until this day. Considerable successes have been made as is manifested in the fact

  16. Nutrient addition differentially affects ecological processes of Avicennia germinans in nitrogen versus phosphorus limited mangrove ecosystems

    USGS Publications Warehouse

    Feller, Ilka C.; Lovelock, C.E.; McKee, K.L.

    2007-01-01

    Nutrient over-enrichment is a major threat to marine environments, but system-specific attributes of coastal ecosystems may result in differences in their sensitivity and susceptibility to eutrophication. We used fertilization experiments in nitrogen (N)- and phosphorus (P)-limited mangrove forests to test the hypothesis that alleviating different kinds of nutrient limitation may have different effects on ecosystem structure and function in natural systems. We compared a broad range of ecological processes to determine if these systems have different thresholds where shifts might occur in nutrient limitation. Growth responses indicated N limitation in Avicennia germinans (black mangrove) forests in the Indian River Lagoon (IRL), Florida, and P limitation at Twin Cays, Belize. When nutrient deficiency was relieved, A. germinans grew out of its stunted form by increasing wood relative to leaf biomass and shoot length relative to lateral growth. At the P-limited site, P enrichment (+P) increased specific leaf area, N resorption, and P uptake, but had no effect on P resorption. At the N-limited site, +N increased both N and P resorption, but did not alter biomass allocation. Herbivory was greater at the P-limited site and was unaffected by +P, whereas +N led to increased herbivory at the N-limited site. The responses to nutrient enrichment depended on the ecological process and limiting nutrient and suggested that N- versus P-limited mangroves do have different thresholds. +P had a greater effect on more ecological processes at Twin Cays than did +N at the IRL, which indicated that the P-limited site was more sensitive to nutrient loading. Because of this sensitivity, eutrophication is more likely to cause a shift in nutrient limitation at P-limited Twin Cays than N-limited IRL. ?? 2007 Springer Science+Business Media, LLC.

  17. Biogeochemical processes underpin ecosystem services

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Elemental cycling is critical to the function of ecosystems and delivery of key ecosystem services because many of these elements are essential nutrients or detrimental toxicants that directly affect the health of organisms and ecosystems. A team of authors from North Carolina State University and ...

  18. Warming Alters Expressions of Microbial Functional Genes Important to Ecosystem Functioning

    PubMed Central

    Xue, Kai; Xie, Jianping; Zhou, Aifen; Liu, Feifei; Li, Dejun; Wu, Liyou; Deng, Ye; He, Zhili; Van Nostrand, Joy D.; Luo, Yiqi; Zhou, Jizhong

    2016-01-01

    Soil microbial communities play critical roles in ecosystem functioning and are likely altered by climate warming. However, so far, little is known about effects of warming on microbial functional gene expressions. Here, we applied functional gene array (GeoChip 3.0) to analyze cDNA reversely transcribed from total RNA to assess expressed functional genes in active soil microbial communities after nine years of experimental warming in a tallgrass prairie. Our results showed that warming significantly altered the community wide gene expressions. Specifically, expressed genes for degrading more recalcitrant carbon were stimulated by warming, likely linked to the plant community shift toward more C4 species under warming and to decrease the long-term soil carbon stability. In addition, warming changed expressed genes in labile C degradation and N cycling in different directions (increase and decrease), possibly reflecting the dynamics of labile C and available N pools during sampling. However, the average abundances of expressed genes in phosphorus and sulfur cycling were all increased by warming, implying a stable trend of accelerated P and S processes which might be a mechanism to sustain higher plant growth. Furthermore, the expressed gene composition was closely related to both dynamic (e.g., soil moisture) and stable environmental attributes (e.g., C4 leaf C or N content), indicating that RNA analyses could also capture certain stable trends in the long-term treatment. Overall, this study revealed the importance of elucidating functional gene expressions of soil microbial community in enhancing our understanding of ecosystem responses to warming. PMID:27199978

  19. Warming Alters Expressions of Microbial Functional Genes Important to Ecosystem Functioning.

    PubMed

    Xue, Kai; Xie, Jianping; Zhou, Aifen; Liu, Feifei; Li, Dejun; Wu, Liyou; Deng, Ye; He, Zhili; Van Nostrand, Joy D; Luo, Yiqi; Zhou, Jizhong

    2016-01-01

    Soil microbial communities play critical roles in ecosystem functioning and are likely altered by climate warming. However, so far, little is known about effects of warming on microbial functional gene expressions. Here, we applied functional gene array (GeoChip 3.0) to analyze cDNA reversely transcribed from total RNA to assess expressed functional genes in active soil microbial communities after nine years of experimental warming in a tallgrass prairie. Our results showed that warming significantly altered the community wide gene expressions. Specifically, expressed genes for degrading more recalcitrant carbon were stimulated by warming, likely linked to the plant community shift toward more C4 species under warming and to decrease the long-term soil carbon stability. In addition, warming changed expressed genes in labile C degradation and N cycling in different directions (increase and decrease), possibly reflecting the dynamics of labile C and available N pools during sampling. However, the average abundances of expressed genes in phosphorus and sulfur cycling were all increased by warming, implying a stable trend of accelerated P and S processes which might be a mechanism to sustain higher plant growth. Furthermore, the expressed gene composition was closely related to both dynamic (e.g., soil moisture) and stable environmental attributes (e.g., C4 leaf C or N content), indicating that RNA analyses could also capture certain stable trends in the long-term treatment. Overall, this study revealed the importance of elucidating functional gene expressions of soil microbial community in enhancing our understanding of ecosystem responses to warming.

  20. Biodiversity and Ecosystem Multi-Functionality: Observed Relationships in Smallholder Fallows in Western Kenya

    PubMed Central

    Sircely, Jason; Naeem, Shahid

    2012-01-01

    Recent studies indicate that species richness can enhance the ability of plant assemblages to support multiple ecosystem functions. To understand how and when ecosystem services depend on biodiversity, it is valuable to expand beyond experimental grasslands. We examined whether plant diversity improves the capacity of agroecosystems to sustain multiple ecosystem services—production of wood and forage, and two elements of soil formation—in two types of smallholder fallows in western Kenya. In 18 grazed and 21 improved fallows, we estimated biomass and quantified soil organic carbon, soil base cations, sand content, and soil infiltration capacity. For four ecosystem functions (wood biomass, forage biomass, soil base cations, steady infiltration rates) linked to the focal ecosystem services, we quantified ecosystem service multi-functionality as (1) the proportion of functions above half-maximum, and (2) mean percentage excess above mean function values, and assessed whether plant diversity or environmental favorability better predicted multi-functionality. In grazed fallows, positive effects of plant diversity best explained the proportion above half-maximum and mean percentage excess, the former also declining with grazing intensity. In improved fallows, the proportion above half-maximum was not associated with soil carbon or plant diversity, while soil carbon predicted mean percentage excess better than diversity. Grazed fallows yielded stronger evidence for diversity effects on multi-functionality, while environmental conditions appeared more influential in improved fallows. The contrast in diversity-multi-functionality relationships among fallow types appears related to differences in management and associated factors including disturbance and species composition. Complementary effects of species with contrasting functional traits on different functions and multi-functional species may have contributed to diversity effects in grazed fallows. Biodiversity and

  1. Municipal sludge metal contamination of old-field ecosystems: Do liming and tilling affect remediation

    SciTech Connect

    Benninger-Truax, M.; Taylor, D.H. . Dept. of Zoology)

    1993-10-01

    Mechanisms of ecosystem recovery following 11 years of sewage sludge disposal were addressed by examining the effects of tilling and/or liming on soil chemistry and the heavy metal (Cd, Cu, Pb, and Zn) concentrations in soil, earthworms, vegetation, spiders, and crickets. In 1989 and 1990, subplots in each of three former 0.1-ha, long-term treatments (sludge, fertilizer, and control) were either unmanipulated or manipulated via tilling and/or liming. Liming significantly increased the pH of soil from the long-term sludge and fertilizer plots, and the combination of tilling and liming affected the heavy metal concentrations in earthworms, as lower concentrations of Cd, Cu, Pb, and Zn were found in earthworms collected from subplots that had been both tilled and limed. However, most observed significant differences in heavy metal concentrations reflected the long-term treatments, as heavy metal concentrations tended to be greater in the soil and biota collected from sludge-treated plots. Thus, heavy metals remained in the soil in forms available to the biota, regardless of the cessation of sludge application or subplot manipulations (liming and/or tilling) for two years following cessation of sludge application.

  2. Microbial interactions affecting the natural transformation of Bacillus subtilis in a model aquatic ecosystem.

    PubMed

    Matsui, Kazuaki; Ishii, Nobuyoshi; Kawabata, Zen'ichiro

    2003-08-01

    The involvement of microbial interactions in natural transformation of bacteria was evaluated using an aquatic model system. For this purpose, the naturally transformable Bacillus subtilis was used as the model bacterium which was co-cultivated with the protist Tetrahymena thermophila (a consumer) and/or the photosynthetic alga Euglena gracilis (a producer). Co-cultivation with as few as 10(2) individuals ml(-1) of T. thermophila lowered the number of transformants to less than the detectable level (<1x10(0) ml(-1)), while co-cultivation with E. gracilis did not. Metabolites from co-cultures of T. thermophila and B. subtilis also decreased the number of transformants to less than the detectable level, while metabolites from co-culture of T. thermophila and B. subtilis with E. gracilis did not. Thus, the introduction of transformation inhibitory factor(s) by the grazing of T. thermophila and the attenuation of this inhibitory factor(s) by E. gracilis is indicated. These observations suggest that biological components do affect the natural transformation of B. subtilis. The study described is the first to suggest that ecological interactions are responsible not only for the carbon and energy cycles, but also for the processes governing horizontal transfer of genes, in microbial ecosystems.

  3. The meaning of functional trait composition of food webs for ecosystem functioning.

    PubMed

    Gravel, Dominique; Albouy, Camille; Thuiller, Wilfried

    2016-05-19

    There is a growing interest in using trait-based approaches to characterize the functional structure of animal communities. Quantitative methods have been derived mostly for plant ecology, but it is now common to characterize the functional composition of various systems such as soils, coral reefs, pelagic food webs or terrestrial vertebrate communities. With the ever-increasing availability of distribution and trait data, a quantitative method to represent the different roles of animals in a community promise to find generalities that will facilitate cross-system comparisons. There is, however, currently no theory relating the functional composition of food webs to their dynamics and properties. The intuitive interpretation that more functional diversity leads to higher resource exploitation and better ecosystem functioning was brought from plant ecology and does not apply readily to food webs. Here we appraise whether there are interpretable metrics to describe the functional composition of food webs that could foster a better understanding of their structure and functioning. We first distinguish the various roles that traits have on food web topology, resource extraction (bottom-up effects), trophic regulation (top-down effects), and the ability to keep energy and materials within the community. We then discuss positive effects of functional trait diversity on food webs, such as niche construction and bottom-up effects. We follow with a discussion on the negative effects of functional diversity, such as enhanced competition (both exploitation and apparent) and top-down control. Our review reveals that most of our current understanding of the impact of functional trait diversity on food web properties and functioning comes from an over-simplistic representation of network structure with well-defined levels. We, therefore, conclude with propositions for new research avenues for both theoreticians and empiricists. PMID:27114571

  4. The meaning of functional trait composition of food webs for ecosystem functioning.

    PubMed

    Gravel, Dominique; Albouy, Camille; Thuiller, Wilfried

    2016-05-19

    There is a growing interest in using trait-based approaches to characterize the functional structure of animal communities. Quantitative methods have been derived mostly for plant ecology, but it is now common to characterize the functional composition of various systems such as soils, coral reefs, pelagic food webs or terrestrial vertebrate communities. With the ever-increasing availability of distribution and trait data, a quantitative method to represent the different roles of animals in a community promise to find generalities that will facilitate cross-system comparisons. There is, however, currently no theory relating the functional composition of food webs to their dynamics and properties. The intuitive interpretation that more functional diversity leads to higher resource exploitation and better ecosystem functioning was brought from plant ecology and does not apply readily to food webs. Here we appraise whether there are interpretable metrics to describe the functional composition of food webs that could foster a better understanding of their structure and functioning. We first distinguish the various roles that traits have on food web topology, resource extraction (bottom-up effects), trophic regulation (top-down effects), and the ability to keep energy and materials within the community. We then discuss positive effects of functional trait diversity on food webs, such as niche construction and bottom-up effects. We follow with a discussion on the negative effects of functional diversity, such as enhanced competition (both exploitation and apparent) and top-down control. Our review reveals that most of our current understanding of the impact of functional trait diversity on food web properties and functioning comes from an over-simplistic representation of network structure with well-defined levels. We, therefore, conclude with propositions for new research avenues for both theoreticians and empiricists.

  5. Alternative hypotheses to explain why biodiversity-ecosystem functioning relationships are concave-up in some natural ecosystems but concave-down in manipulative experiments

    NASA Astrophysics Data System (ADS)

    Mora, Camilo; Danovaro, Roberto; Loreau, Michel

    2014-06-01

    Recent studies of the relationship between biodiversity and functioning in marine ecosystems have yielded non-saturating patterns that contrast sharply with the results of experimental studies, where ecosystem functioning rapidly saturates with increases in biodiversity. Here we provide a simple theoretical framework of three alternative hypotheses that, individually or combined, are likely to explain this contrast: i) the use of functional richness instead of species richness, ii) an increased production efficiency of species in producing biomass when more ecological interactions are present, and iii) the fact that communities are likely assembled in an ordered succession of species from low to high ecological efficiency. Our results provide theoretical support for concave-up biodiversity-ecosystem functioning relationships in natural ecosystems and confirm that the loss of species can have substantially larger effects on the functioning of natural ecosystems than anticipated from controlled manipulative experiments.

  6. Alternative hypotheses to explain why biodiversity-ecosystem functioning relationships are concave-up in some natural ecosystems but concave-down in manipulative experiments.

    PubMed

    Mora, Camilo; Danovaro, Roberto; Loreau, Michel

    2014-06-25

    Recent studies of the relationship between biodiversity and functioning in marine ecosystems have yielded non-saturating patterns that contrast sharply with the results of experimental studies, where ecosystem functioning rapidly saturates with increases in biodiversity. Here we provide a simple theoretical framework of three alternative hypotheses that, individually or combined, are likely to explain this contrast: i) the use of functional richness instead of species richness, ii) an increased production efficiency of species in producing biomass when more ecological interactions are present, and iii) the fact that communities are likely assembled in an ordered succession of species from low to high ecological efficiency. Our results provide theoretical support for concave-up biodiversity-ecosystem functioning relationships in natural ecosystems and confirm that the loss of species can have substantially larger effects on the functioning of natural ecosystems than anticipated from controlled manipulative experiments.

  7. Quantifying causal mechanisms to determine how protected areas affect poverty through changes in ecosystem services and infrastructure.

    PubMed

    Ferraro, Paul J; Hanauer, Merlin M

    2014-03-18

    To develop effective environmental policies, we must understand the mechanisms through which the policies affect social and environmental outcomes. Unfortunately, empirical evidence about these mechanisms is limited, and little guidance for quantifying them exists. We develop an approach to quantifying the mechanisms through which protected areas affect poverty. We focus on three mechanisms: changes in tourism and recreational services; changes in infrastructure in the form of road networks, health clinics, and schools; and changes in regulating and provisioning ecosystem services and foregone production activities that arise from land-use restrictions. The contributions of ecotourism and other ecosystem services to poverty alleviation in the context of a real environmental program have not yet been empirically estimated. Nearly two-thirds of the poverty reduction associated with the establishment of Costa Rican protected areas is causally attributable to opportunities afforded by tourism. Although protected areas reduced deforestation and increased regrowth, these land cover changes neither reduced nor exacerbated poverty, on average. Protected areas did not, on average, affect our measures of infrastructure and thus did not contribute to poverty reduction through this mechanism. We attribute the remaining poverty reduction to unobserved dimensions of our mechanisms or to other mechanisms. Our study empirically estimates previously unidentified contributions of ecotourism and other ecosystem services to poverty alleviation in the context of a real environmental program. We demonstrate that, with existing data and appropriate empirical methods, conservation scientists and policymakers can begin to elucidate the mechanisms through which ecosystem conservation programs affect human welfare.

  8. Quantifying causal mechanisms to determine how protected areas affect poverty through changes in ecosystem services and infrastructure.

    PubMed

    Ferraro, Paul J; Hanauer, Merlin M

    2014-03-18

    To develop effective environmental policies, we must understand the mechanisms through which the policies affect social and environmental outcomes. Unfortunately, empirical evidence about these mechanisms is limited, and little guidance for quantifying them exists. We develop an approach to quantifying the mechanisms through which protected areas affect poverty. We focus on three mechanisms: changes in tourism and recreational services; changes in infrastructure in the form of road networks, health clinics, and schools; and changes in regulating and provisioning ecosystem services and foregone production activities that arise from land-use restrictions. The contributions of ecotourism and other ecosystem services to poverty alleviation in the context of a real environmental program have not yet been empirically estimated. Nearly two-thirds of the poverty reduction associated with the establishment of Costa Rican protected areas is causally attributable to opportunities afforded by tourism. Although protected areas reduced deforestation and increased regrowth, these land cover changes neither reduced nor exacerbated poverty, on average. Protected areas did not, on average, affect our measures of infrastructure and thus did not contribute to poverty reduction through this mechanism. We attribute the remaining poverty reduction to unobserved dimensions of our mechanisms or to other mechanisms. Our study empirically estimates previously unidentified contributions of ecotourism and other ecosystem services to poverty alleviation in the context of a real environmental program. We demonstrate that, with existing data and appropriate empirical methods, conservation scientists and policymakers can begin to elucidate the mechanisms through which ecosystem conservation programs affect human welfare. PMID:24567397

  9. Effects of Detrital Subsidies on Soft-Sediment Ecosystem Function Are Transient and Source-Dependent

    PubMed Central

    Gladstone-Gallagher, Rebecca V.; Lohrer, Andrew M.; Lundquist, Carolyn J.; Pilditch, Conrad A.

    2016-01-01

    Detrital subsidies from marine macrophytes are prevalent in temperate estuaries, and their role in structuring benthic macrofaunal communities is well documented, but the resulting impact on ecosystem function is not understood. We conducted a field experiment to test the effects of detrital decay on soft-sediment primary production, community metabolism and nutrient regeneration (measures of ecosystem function). Twenty four (2 m2) plots were established on an intertidal sandflat, to which we added 0 or 220 g DW m-2 of detritus from either mangroves (Avicennia marina), seagrass (Zostera muelleri), or kelp (Ecklonia radiata) (n = 6 plots per treatment). Then, after 4, 17 and 46 d we measured ecosystem function, macrofaunal community structure and sediment properties. We hypothesized that (1) detrital decay would stimulate benthic primary production either by supplying nutrients to the benthic macrophytes, or by altering the macrofaunal community; and (2) ecosystem responses would depend on the stage and rate of macrophyte decay (a function of source). Avicennia detritus decayed the slowest with a half-life (t50) of 46 d, while Zostera and Ecklonia had t50 values of 28 and 2.6 d, respectively. However, ecosystem responses were not related to these differences. Instead, we found transient effects (up to 17 d) of Avicennia and Ecklonia detritus on benthic primary production, where initially (4 d) these detrital sources suppressed primary production, but after 17 d, primary production was stimulated in Avicennia plots relative to controls. Other ecosystem function response variables and the macrofaunal community composition were not altered by the addition of detritus, but did vary with time. By sampling ecosystem function temporally, we were able to capture the in situ transient effects of detrital subsidies on important benthic ecosystem functions. PMID:27138563

  10. Effects of Detrital Subsidies on Soft-Sediment Ecosystem Function Are Transient and Source-Dependent.

    PubMed

    Gladstone-Gallagher, Rebecca V; Lohrer, Andrew M; Lundquist, Carolyn J; Pilditch, Conrad A

    2016-01-01

    Detrital subsidies from marine macrophytes are prevalent in temperate estuaries, and their role in structuring benthic macrofaunal communities is well documented, but the resulting impact on ecosystem function is not understood. We conducted a field experiment to test the effects of detrital decay on soft-sediment primary production, community metabolism and nutrient regeneration (measures of ecosystem function). Twenty four (2 m2) plots were established on an intertidal sandflat, to which we added 0 or 220 g DW m-2 of detritus from either mangroves (Avicennia marina), seagrass (Zostera muelleri), or kelp (Ecklonia radiata) (n = 6 plots per treatment). Then, after 4, 17 and 46 d we measured ecosystem function, macrofaunal community structure and sediment properties. We hypothesized that (1) detrital decay would stimulate benthic primary production either by supplying nutrients to the benthic macrophytes, or by altering the macrofaunal community; and (2) ecosystem responses would depend on the stage and rate of macrophyte decay (a function of source). Avicennia detritus decayed the slowest with a half-life (t50) of 46 d, while Zostera and Ecklonia had t50 values of 28 and 2.6 d, respectively. However, ecosystem responses were not related to these differences. Instead, we found transient effects (up to 17 d) of Avicennia and Ecklonia detritus on benthic primary production, where initially (4 d) these detrital sources suppressed primary production, but after 17 d, primary production was stimulated in Avicennia plots relative to controls. Other ecosystem function response variables and the macrofaunal community composition were not altered by the addition of detritus, but did vary with time. By sampling ecosystem function temporally, we were able to capture the in situ transient effects of detrital subsidies on important benthic ecosystem functions. PMID:27138563

  11. Large-Scale Variation in Combined Impacts of Canopy Loss and Disturbance on Community Structure and Ecosystem Functioning

    PubMed Central

    Crowe, Tasman P.; Cusson, Mathieu; Bulleri, Fabio; Davoult, Dominique; Arenas, Francisco; Aspden, Rebecca; Benedetti-Cecchi, Lisandro; Bevilacqua, Stanislao; Davidson, Irvine; Defew, Emma; Fraschetti, Simonetta; Golléty, Claire; Griffin, John N.; Herkül, Kristjan; Kotta, Jonne; Migné, Aline; Molis, Markus; Nicol, Sophie K.; Noël, Laure M-L J.; Pinto, Isabel Sousa; Valdivia, Nelson; Vaselli, Stefano; Jenkins, Stuart R.

    2013-01-01

    Ecosystems are under pressure from multiple human disturbances whose impact may vary depending on environmental context. We experimentally evaluated variation in the separate and combined effects of the loss of a key functional group (canopy algae) and physical disturbance on rocky shore ecosystems at nine locations across Europe. Multivariate community structure was initially affected (during the first three to six months) at six locations but after 18 months, effects were apparent at only three. Loss of canopy caused increases in cover of non-canopy algae in the three locations in southern Europe and decreases in some northern locations. Measures of ecosystem functioning (community respiration, gross primary productivity, net primary productivity) were affected by loss of canopy at five of the six locations for which data were available. Short-term effects on community respiration were widespread, but effects were rare after 18 months. Functional changes corresponded with changes in community structure and/or species richness at most locations and times sampled, but no single aspect of biodiversity was an effective predictor of longer-term functional changes. Most ecosystems studied were able to compensate in functional terms for impacts caused by indiscriminate physical disturbance. The only consistent effect of disturbance was to increase cover of non-canopy species. Loss of canopy algae temporarily reduced community resistance to disturbance at only two locations and at two locations actually increased resistance. Resistance to disturbance-induced changes in gross primary productivity was reduced by loss of canopy algae at four locations. Location-specific variation in the effects of the same stressors argues for flexible frameworks for the management of marine environments. These results also highlight the need to analyse how species loss and other stressors combine and interact in different environmental contexts. PMID:23799082

  12. Nitrogen and carbon cycling in a grassland community ecosystem as affected by elevated atmospheric CO2

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Increasing global atmospheric CO2 concentration has led to concerns regarding its potential effects on terrestrial ecosystem and the long-term storage of C and N in soil. This study examined responses to elevated CO2 in a grass ecosystem invaded with a leguminous shrub Acacia farnesiana (L.) Willd (...

  13. Nutrient Enrichment and Food Web Composition Affect Ecosystem Metabolism in an Experimental Seagrass Habitat

    PubMed Central

    Spivak, Amanda C.; Canuel, Elizabeth A.; Duffy, J. Emmett; Richardson, J. Paul

    2009-01-01

    Background Food web composition and resource levels can influence ecosystem properties such as productivity and elemental cycles. In particular, herbivores occupy a central place in food webs as the species richness and composition of this trophic level may simultaneously influence the transmission of resource and predator effects to higher and lower trophic levels, respectively. Yet, these interactions are poorly understood. Methodology/Principal Findings Using an experimental seagrass mesocosm system, we factorially manipulated water column nutrient concentrations, food chain length, and diversity of crustacean grazers to address two questions: (1) Does food web composition modulate the effects of nutrient enrichment on plant and grazer biomasses and stoichiometry? (2) Do ecosystem fluxes of dissolved oxygen and nutrients more closely reflect above-ground biomass and community structure or sediment processes? Nutrient enrichment and grazer presence generally had strong effects on biomass accumulation, stoichiometry, and ecosystem fluxes, whereas predator effects were weaker or absent. Nutrient enrichment had little effect on producer biomass or net ecosystem production but strongly increased seagrass nutrient content, ecosystem flux rates, and grazer secondary production, suggesting that enhanced production was efficiently transferred from producers to herbivores. Gross ecosystem production (oxygen evolution) correlated positively with above-ground plant biomass, whereas inorganic nutrient fluxes were unrelated to plant or grazer biomasses, suggesting dominance by sediment microbial processes. Finally, grazer richness significantly stabilized ecosystem processes, as predators decreased ecosystem production and respiration only in the zero- and one- species grazer treatments. Conclusions/Significance Overall, our results indicate that consumer presence and species composition strongly influence ecosystem responses to nutrient enrichment, and that increasing

  14. The exergy of a phase shift: Ecosystem functioning loss in seagrass meadows of the Mediterranean Sea

    NASA Astrophysics Data System (ADS)

    Montefalcone, Monica; Vassallo, Paolo; Gatti, Giulia; Parravicini, Valeriano; Paoli, Chiara; Morri, Carla; Bianchi, Carlo Nike

    2015-04-01

    Sustained functioning of ecosystems is predicted to depend upon the maintenance of their biodiversity, structure and integrity. The large consensus achieved in this regard, however, faces to the objective difficulty of finding appropriate metrics to measure ecosystem functioning. Here, we aim at evaluating functional consequence of the phase shift occurring in meadows of the Mediterranean seagrass Posidonia oceanica, a priority habitat that is undergoing regression in many coastal areas due to multiple human pressures. Structural degradation of the P. oceanica ecosystem, consequent to increasing coastal exploitation and climate change, may result in the progressive replacement of this seagrass by opportunistic macrophytes, either native or alien. Reviewing published information and our personal records, we measured changes in biological habitat provisioning, species richness and biomass associated to each of the alternative states characterizing the phase shift. Then, ecosystem functioning was assessed by computing the exergy associated to each state, exergy being a state variable that measures the ecosystem capacity to produce work. Phase shift was consistently shown to imply loss in habitat provision, species richness, and biomass; structural and compositional loss was parallelled by a reduction of exergy content, thus providing for the first time an objective and integrative measure of the loss of ecosystem functioning following the degradation of healthy seagrass meadows.

  15. Plant functional traits and diversity in sand dune ecosystems across different biogeographic regions

    NASA Astrophysics Data System (ADS)

    Mahdavi, P.; Bergmeier, E.

    2016-07-01

    Plant species of a functional group respond similarly to environmental pressures and may be expected to act similarly on ecosystem processes and habitat properties. However, feasibility and applicability of functional groups in ecosystems across very different climatic regions have not yet been studied. In our approach we specified the functional groups in sand dune ecosystems of the Mediterranean, Hyrcanian and Irano-Turanian phytogeographic regions. We examined whether functional groups are more influenced by region or rather by habitat characteristics, and identified trait syndromes associated with common habitat types in sand dunes (mobile dunes, stabilized dunes, salt marshes, semi-wet sands, disturbed habitats). A database of 14 traits, 309 species and 314 relevés was examined and trait-species, trait-plot and species-plot matrices were built. Cluster analysis revealed similar plant functional groups in sand dune ecosystems across regions of very different species composition and climate. Specifically, our study showed that plant traits in sand dune ecosystems are grouped reflecting habitat affiliation rather than region and species pool. Environmental factors and constraints such as sand mobility, soil salinity, water availability, nutrient status and disturbance are more important for the occurrence and distribution of plant functional groups than regional belonging. Each habitat is shown to be equipped with specific functional groups and can be described by specific sets of traits. In restoration ecology the completeness of functional groups and traits in a site may serve as a guideline for maintaining or restoring the habitat.

  16. Ecosystem sensitivity to climate warming: A modeling approach

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Warmer atmospheric temperatures will affect ecosystem functioning directly through changes in metabolic rate and tissue damage of organisms. Indirectly, increased temperatures can also affect ecosystem water balance with increased evapotranspiration (from bare-soil evaporation and transpiration) tha...

  17. Uncertainty of Monetary Valued Ecosystem Services - Value Transfer Functions for Global Mapping.

    PubMed

    Schmidt, Stefan; Manceur, Ameur M; Seppelt, Ralf

    2016-01-01

    Growing demand of resources increases pressure on ecosystem services (ES) and biodiversity. Monetary valuation of ES is frequently seen as a decision-support tool by providing explicit values for unconsidered, non-market goods and services. Here we present global value transfer functions by using a meta-analytic framework for the synthesis of 194 case studies capturing 839 monetary values of ES. For 12 ES the variance of monetary values could be explained with a subset of 93 study- and site-specific variables by utilizing boosted regression trees. This provides the first global quantification of uncertainties and transferability of monetary valuations. Models explain from 18% (water provision) to 44% (food provision) of variance and provide statistically reliable extrapolations for 70% (water provision) to 91% (food provision) of the terrestrial earth surface. Although the application of different valuation methods is a source of uncertainty, we found evidence that assuming homogeneity of ecosystems is a major error in value transfer function models. Food provision is positively correlated with better life domains and variables indicating positive conditions for human well-being. Water provision and recreation service show that weak ownerships affect valuation of other common goods negatively (e.g. non-privately owned forests). Furthermore, we found support for the shifting baseline hypothesis in valuing climate regulation. Ecological conditions and societal vulnerability determine valuation of extreme event prevention. Valuation of habitat services is negatively correlated with indicators characterizing less favorable areas. Our analysis represents a stepping stone to establish a standardized integration of and reporting on uncertainties for reliable and valid benefit transfer as an important component for decision support. PMID:26938447

  18. Uncertainty of Monetary Valued Ecosystem Services – Value Transfer Functions for Global Mapping

    PubMed Central

    Schmidt, Stefan; Manceur, Ameur M.; Seppelt, Ralf

    2016-01-01

    Growing demand of resources increases pressure on ecosystem services (ES) and biodiversity. Monetary valuation of ES is frequently seen as a decision-support tool by providing explicit values for unconsidered, non-market goods and services. Here we present global value transfer functions by using a meta-analytic framework for the synthesis of 194 case studies capturing 839 monetary values of ES. For 12 ES the variance of monetary values could be explained with a subset of 93 study- and site-specific variables by utilizing boosted regression trees. This provides the first global quantification of uncertainties and transferability of monetary valuations. Models explain from 18% (water provision) to 44% (food provision) of variance and provide statistically reliable extrapolations for 70% (water provision) to 91% (food provision) of the terrestrial earth surface. Although the application of different valuation methods is a source of uncertainty, we found evidence that assuming homogeneity of ecosystems is a major error in value transfer function models. Food provision is positively correlated with better life domains and variables indicating positive conditions for human well-being. Water provision and recreation service show that weak ownerships affect valuation of other common goods negatively (e.g. non-privately owned forests). Furthermore, we found support for the shifting baseline hypothesis in valuing climate regulation. Ecological conditions and societal vulnerability determine valuation of extreme event prevention. Valuation of habitat services is negatively correlated with indicators characterizing less favorable areas. Our analysis represents a stepping stone to establish a standardized integration of and reporting on uncertainties for reliable and valid benefit transfer as an important component for decision support. PMID:26938447

  19. Long-term and large-scale perspectives on the relationship between biodiversity and ecosystem functioning

    USGS Publications Warehouse

    Symstad, A.J.; Chapin, F. S.; Wall, D.H.; Gross, K.L.; Huenneke, L.F.; Mittelbach, G.G.; Peters, D.P.C.; Tilman, D.

    2003-01-01

    In a growing body of literature from a variety of ecosystems is strong evidence that various components of biodiversity have significant impacts on ecosystem functioning. However, much of this evidence comes from short-term, small-scale experiments in which communities are synthesized from relatively small species pools and conditions are highly controlled. Extrapolation of the results of such experiments to longer time scales and larger spatial scales - those of whole ecosystems - is difficult because the experiments do not incorporate natural processes such as recruitment limitation and colonization of new species. We show how long-term study of planned and accidental changes in species richness and composition suggests that the effects of biodiversity on ecosystem functioning will vary over time and space. More important, we also highlight areas of uncertainty that need to be addressed through coordinated cross-scale and cross-site research.

  20. Continental-scale effects of nutrient pollution on stream ecosystem functioning.

    PubMed

    Woodward, Guy; Gessner, Mark O; Giller, Paul S; Gulis, Vladislav; Hladyz, Sally; Lecerf, Antoine; Malmqvist, Björn; McKie, Brendan G; Tiegs, Scott D; Cariss, Helen; Dobson, Mike; Elosegi, Arturo; Ferreira, Verónica; Graça, Manuel A S; Fleituch, Tadeusz; Lacoursière, Jean O; Nistorescu, Marius; Pozo, Jesús; Risnoveanu, Geta; Schindler, Markus; Vadineanu, Angheluta; Vought, Lena B-M; Chauvet, Eric

    2012-06-15

    Excessive nutrient loading is a major threat to aquatic ecosystems worldwide that leads to profound changes in aquatic biodiversity and biogeochemical processes. Systematic quantitative assessment of functional ecosystem measures for river networks is, however, lacking, especially at continental scales. Here, we narrow this gap by means of a pan-European field experiment on a fundamental ecosystem process--leaf-litter breakdown--in 100 streams across a greater than 1000-fold nutrient gradient. Dramatically slowed breakdown at both extremes of the gradient indicated strong nutrient limitation in unaffected systems, potential for strong stimulation in moderately altered systems, and inhibition in highly polluted streams. This large-scale response pattern emphasizes the need to complement established structural approaches (such as water chemistry, hydrogeomorphology, and biological diversity metrics) with functional measures (such as litter-breakdown rate, whole-system metabolism, and nutrient spiraling) for assessing ecosystem health.

  1. Impacts of shrub encroachment on ecosystem structure and functioning: towards a global synthesis

    PubMed Central

    Eldridge, David J.; Bowker, Matthew A.; Maestre, Fernando T.; Roger, Erin; Reynolds, James F.; Whitford, Walter G.

    2013-01-01

    Encroachment of woody plants into grasslands has generated considerable interest among ecologists. Syntheses of encroachment effects on ecosystem processes have been limited in extent and confined largely to pastoral land uses or particular geographical regions. We used univariate analyses, meta-analysis and structural equation modeling to test the propositions that 1) shrub encroachment does not necessarily lead to declines in ecosystem functions, and 2) shrub traits influence the functional outcome of encroachment. Analyses of 43 ecosystem attributes from 244 case studies worldwide showed that some attributes consistently increased with encroachment (e.g. soil C, N), and others declined (e.g. grass cover, pH), but most exhibited variable responses. Traits of shrubs were associated with significant, though weak, structural and functional outcomes of encroachment. Our review revealed that encroachment had mixed effects on ecosystem structure and functioning at global scales, and that shrub traits influence the functional outcome of encroachment. Thus, a simple designation of encroachment as a process leading to functionally, structurally or contextually degraded ecosystems is not supported by a critical analysis of existing literature. Our results highlight that the commonly established link between shrub encroachment and degradation is not universal. PMID:21592276

  2. Considerations on a data-driven approach to identify plant's imprint on ecosystem functioning

    NASA Astrophysics Data System (ADS)

    Musavi, Talie; Kattge, Jens; Mahecha, Miguel; Reichstein, Markus; Van de Weg, Martine Janet; Van Bodegom, Peter; Bahn, Michael; Migliavacca, Mirco; Wirth, Christian; Reich, Peter

    2015-04-01

    Terrestrial ecosystems strongly determine the exchange of carbon, water and energy between the biosphere and atmosphere. These exchanges are influenced and partly driven by environmental conditions (e.g. local meteorology, soils), but generally mediated by organisms. In commonly used terrestrial biosphere models, this principle is implemented by process-based descriptions of plant functioning at the organ level. In order to validate these model formulations, we need an independent empirical approach to understand the plant's imprint on ecosystem functioning. We use land-atmosphere exchange of fluxes of CO2, H2O and energy in tandem with environmental controls available in FLUXNET to quantify "ecosystem functional properties" (EFPs). The latter are generally time-invariant ecosystem specific properties, for instance process sensitivities or efficiencies that shape ecosystem scale responses. Our crucial question is if plant traits measured at the organ level (available e.g. in the TRY database) can elucidate the characteristics of EFPs. In this study we follow this new avenue and link the two global databases FLUXNET and TRY to study the role of plants for biogeochemical cycles across a large number of different globally distributed ecosystem types. We aim to address emerging difficulties and possible solutions. For instance, we show that using average values of plant traits from TRY that are not necessarily measured at the fluxnet sites is of use but has clear limitations. However having information on the amount of vegetation at the sites derived from remote sensing is needed for weighting the plant traits. In addition, we have to consider that EFPs are not really time-invariant and subject to alterations after disturbance, meteorological extremes, management etc. Overall, we provide an outlook on perspectives and applications of empirical analyses of plants' imprint on ecosystem functioning by combining remote sensing, in situ measured plant traits and ecosystem

  3. How does wind-throw disturbance affect the carbon budget of an upland spruce forest ecosystem?

    NASA Astrophysics Data System (ADS)

    Lindauer, Matthias; Schmid, Hans Peter; Grote, Rüdiger; Mauder, Matthias; Wolpert, Benjamin; Steinbrecher, Rainer

    2014-05-01

    Forests, especially in mid-latitudes are generally designated as large carbon sinks. However, stand-replacing disturbance events like fires, insect-infestations, or severe wind-storms can shift an ecosystem from carbon sink to carbon source within short time and keep it as this for a long time. In Addition, extreme weather situations which promote the occurrence of ecosystem disturbances are likely to increase in the future due to climate change. The development and competition of different vegetation types (spruce vs. grass) as well as soil organic matter (SOM), and their contribution to the net ecosystem exchange (NEE), in such disturbed forest ecosystems are largely unknown. In a large wind-throw area (ca. 600 m diameter, due to cyclone Kyrill in January 2007) within a mature upland spruce forest, where dead-wood has not been removed, in the Bavarian Forest National Park (Lackenberg, 1308 m a.s.l., Bavaria, Germany), fluxes of CO2, water vapor and energy have been measured with the Eddy Covariance (EC) method since 2009. Model simulations (MoBiLE) were used to estimate the GPP components from trees and grassland as well as to differentiate between soil and plant respiration, and to get an idea about the long term behavior of the ecosystems carbon exchange. For 2009, 2010, 2011, 2012, and 2013 estimates of annual Net Ecosystem Exchange (NEE) showed that the wind-throw was a marked carbon source. However, the few remaining trees and newly emerging vegetation (grass, sparse young spruce, etc.) lead to an already strong Gross Ecosystem Production (GEP). Model simulations conformed well with the measurements. To our knowledge, we present the worldwide first long-term measurements of NEE within a non-cleared wind-throw-disturbed forest ecosystem.

  4. Linking hydrology, ecosystem function, and livelihood sustainability in African papyrus wetlands using a Bayesian Network Model

    NASA Astrophysics Data System (ADS)

    van Dam, A.; Gettel, G. M.; Kipkemboi, J.; Rahman, M. M.

    2011-12-01

    Papyrus wetlands in East Africa provide ecosystem services supporting the livelihoods of millions but are rapidly degrading due to economic development. For ecosystem conservation, an integrated understanding of the natural and social processes driving ecosystem change is needed. This research focuses on integrating the causal relationships between hydrology, ecosystem function, and livelihood sustainability in Nyando wetland, western Kenya. Livelihood sustainability is based on ecosystem services that include plant and animal harvest for building material and food, conversion of wetlands to crop and grazing land, water supply, and water quality regulation. Specific objectives were: to integrate studies of hydrology, ecology, and livelihood activities using a Bayesian Network (BN) model and include stakeholder involvement in model development. The BN model (Netica 4.16) had 35 nodes with seven decision nodes describing demography, economy, papyrus market, and rainfall, and two target nodes describing ecosystem function (defined by groundwater recharge, nutrient and sediment retention, and biodiversity) and livelihood sustainability (drinking water supply, crop production, livestock production, and papyrus yield). The conditional probability tables were populated using results of ecohydrological and socio-economic field work and consultations with stakeholders. The model was evaluated for an average year with decision node probabilities set according to data from research, expert opinion, and stakeholders' views. Then, scenarios for dry and wet seasons and for economic development (low population growth and unemployment) and policy development (more awareness of wetland value) were evaluated. In an average year, the probability for maintaining a "good" level of sediment and nutrient retention functions, groundwater recharge, and biodiversity was about 60%. ("Good" is defined by expert opinion based on ongoing field research.) In the dry season, the probability was

  5. Positive and negative affective processing exhibit dissociable functional hubs during the viewing of affective pictures.

    PubMed

    Zhang, Wenhai; Li, Hong; Pan, Xiaohong

    2015-02-01

    Recent resting-state functional magnetic resonance imaging (fMRI) studies using graph theory metrics have revealed that the functional network of the human brain possesses small-world characteristics and comprises several functional hub regions. However, it is unclear how the affective functional network is organized in the brain during the processing of affective information. In this study, the fMRI data were collected from 25 healthy college students as they viewed a total of 81 positive, neutral, and negative pictures. The results indicated that affective functional networks exhibit weaker small-worldness properties with higher local efficiency, implying that local connections increase during viewing affective pictures. Moreover, positive and negative emotional processing exhibit dissociable functional hubs, emerging mainly in task-positive regions. These functional hubs, which are the centers of information processing, have nodal betweenness centrality values that are at least 1.5 times larger than the average betweenness centrality of the network. Positive affect scores correlated with the betweenness values of the right orbital frontal cortex (OFC) and the right putamen in the positive emotional network; negative affect scores correlated with the betweenness values of the left OFC and the left amygdala in the negative emotional network. The local efficiencies in the left superior and inferior parietal lobe correlated with subsequent arousal ratings of positive and negative pictures, respectively. These observations provide important evidence for the organizational principles of the human brain functional connectome during the processing of affective information.

  6. Trophic interactions, ecosystem structure and function in the southern Yellow Sea

    NASA Astrophysics Data System (ADS)

    Lin, Qun; Jin, Xianshi; Zhang, Bo

    2013-01-01

    The southern Yellow Sea is an important fishing ground, providing abundant fishery resources. However, overfishing and climate change have caused a decline in the resource and damaged the ecosystem. We developed an ecosystem model to analyze the trophic interactions and ecosystem structure and function to guide sustainable development of the ecosystem. A trophic mass-balance model of the southern Yellow Sea during 2000-2001 was constructed using Ecopath with Ecosim software. We defined 22 important functional groups and studied their diet composition. The trophic levels of fish, shrimp, crabs, and cephalopods were between 2.78 and 4.39, and the mean trophic level of the fisheries was 3.24. The trophic flows within the food web occurred primarily in the lower trophic levels. The mean trophic transfer efficiency was 8.1%, of which 7.1% was from primary producers and 9.3% was from detritus within the ecosystem. The transfer efficiency between trophic levels II to III to IV to V to >V was 5.0%, 5.7%, 18.5%, and 19.7%-20.4%, respectively. Of the total flow, phytoplankton contributed 61% and detritus contributed 39%. Fishing is defined as a top predator within the ecosystem, and has a negative impact on most commercial species. Moreover, the ecosystem had a high gross efficiency of the fishery and a high value of primary production required to sustain the fishery. Together, our data suggest there is high fishing pressure in the southern Yellow Sea. Based on analysis of Odum's ecological parameters, this ecosystem was at an immature stage. Our results provide some insights into the structure and development of this ecosystem.

  7. Seafloor heterogeneity influences the biodiversity–ecosystem functioning relationships in the deep sea

    PubMed Central

    Zeppilli, Daniela; Pusceddu, Antonio; Trincardi, Fabio; Danovaro, Roberto

    2016-01-01

    Theoretical ecology predicts that heterogeneous habitats allow more species to co-exist in a given area. In the deep sea, biodiversity is positively linked with ecosystem functioning, suggesting that deep-seabed heterogeneity could influence ecosystem functions and the relationships between biodiversity and ecosystem functioning (BEF). To shed light on the BEF relationships in a heterogeneous deep seabed, we investigated variations in meiofaunal biodiversity, biomass and ecosystem efficiency within and among different seabed morphologies (e.g., furrows, erosional troughs, sediment waves and other depositional structures, landslide scars and deposits) in a narrow geo-morphologically articulated sector of the Adriatic Sea. We show that distinct seafloor morphologies are characterized by highly diverse nematode assemblages, whereas areas sharing similar seabed morphologies host similar nematode assemblages. BEF relationships are consistently positive across the entire region, but different seabed morphologies are characterised by different slope coefficients of the relationship. Our results suggest that seafloor heterogeneity, allowing diversified assemblages across different habitats, increases diversity and influence ecosystem processes at the regional scale, and BEF relationships at smaller spatial scales. We conclude that high-resolution seabed mapping and a detailed analysis of the species distribution at the habitat scale are crucial for improving management of goods and services delivered by deep-sea ecosystems. PMID:27211908

  8. Seafloor heterogeneity influences the biodiversity–ecosystem functioning relationships in the deep sea

    NASA Astrophysics Data System (ADS)

    Zeppilli, Daniela; Pusceddu, Antonio; Trincardi, Fabio; Danovaro, Roberto

    2016-05-01

    Theoretical ecology predicts that heterogeneous habitats allow more species to co-exist in a given area. In the deep sea, biodiversity is positively linked with ecosystem functioning, suggesting that deep-seabed heterogeneity could influence ecosystem functions and the relationships between biodiversity and ecosystem functioning (BEF). To shed light on the BEF relationships in a heterogeneous deep seabed, we investigated variations in meiofaunal biodiversity, biomass and ecosystem efficiency within and among different seabed morphologies (e.g., furrows, erosional troughs, sediment waves and other depositional structures, landslide scars and deposits) in a narrow geo-morphologically articulated sector of the Adriatic Sea. We show that distinct seafloor morphologies are characterized by highly diverse nematode assemblages, whereas areas sharing similar seabed morphologies host similar nematode assemblages. BEF relationships are consistently positive across the entire region, but different seabed morphologies are characterised by different slope coefficients of the relationship. Our results suggest that seafloor heterogeneity, allowing diversified assemblages across different habitats, increases diversity and influence ecosystem processes at the regional scale, and BEF relationships at smaller spatial scales. We conclude that high-resolution seabed mapping and a detailed analysis of the species distribution at the habitat scale are crucial for improving management of goods and services delivered by deep-sea ecosystems.

  9. Seafloor heterogeneity influences the biodiversity-ecosystem functioning relationships in the deep sea.

    PubMed

    Zeppilli, Daniela; Pusceddu, Antonio; Trincardi, Fabio; Danovaro, Roberto

    2016-01-01

    Theoretical ecology predicts that heterogeneous habitats allow more species to co-exist in a given area. In the deep sea, biodiversity is positively linked with ecosystem functioning, suggesting that deep-seabed heterogeneity could influence ecosystem functions and the relationships between biodiversity and ecosystem functioning (BEF). To shed light on the BEF relationships in a heterogeneous deep seabed, we investigated variations in meiofaunal biodiversity, biomass and ecosystem efficiency within and among different seabed morphologies (e.g., furrows, erosional troughs, sediment waves and other depositional structures, landslide scars and deposits) in a narrow geo-morphologically articulated sector of the Adriatic Sea. We show that distinct seafloor morphologies are characterized by highly diverse nematode assemblages, whereas areas sharing similar seabed morphologies host similar nematode assemblages. BEF relationships are consistently positive across the entire region, but different seabed morphologies are characterised by different slope coefficients of the relationship. Our results suggest that seafloor heterogeneity, allowing diversified assemblages across different habitats, increases diversity and influence ecosystem processes at the regional scale, and BEF relationships at smaller spatial scales. We conclude that high-resolution seabed mapping and a detailed analysis of the species distribution at the habitat scale are crucial for improving management of goods and services delivered by deep-sea ecosystems. PMID:27211908

  10. Hydrologic Alteration and Response of Ecosystem Functions to River Restoration

    NASA Astrophysics Data System (ADS)

    Orr, C. H.; Stanley, E. H.

    2005-12-01

    Stream ecology theory suggests that physical and hydrologic setting is often a dominant determinant of ecosystem structure in fluvial systems. Restorationist practitioners may work under the assumption that if the hydrologic parameters that control biological processes are restored, biotic components of interest should be restored as well. This method is sometimes called passive habitat restoration, or an eco-hydromorphic approach. An alternate to this hypothesis is that biological recovery is constrained by a number of other limitations such as distance to a source population, site history, and presence of invasive species. In this scenario, systems will not be restored by hydrologic alterations alone. To address the influence physical setting has on ecological process, we measured three specific ecological responses of streams to hydrologic manipulations separate restoration projects in Central Wisconsin. The projects shared the common trait of being primarily hydrologic alterations. We measured phosphorus retention capacity in a second-order stream before and after a pair of small dam removals, denitrification rates following the reflooding of a leveed floodplain and an approximately 50-year time series of vegetation recolonization on exposed mud flats following dam removal. In each case the measured responses showed unexpectedly large variability and there was not close correlation between physical and ecologic parameters. Such high variability in response to alterations also made it difficult to determine if the restorations met their goals. One conclusion of these studies may be that we need to move beyond hydrologic alterations to address additional manipulations to better meet the goals of specific projects.

  11. Cryptic diversity and ecosystem functioning: a complex tale of differential effects on decomposition.

    PubMed

    De Meester, N; Gingold, R; Rigaux, A; Derycke, S; Moens, T

    2016-10-01

    Marine ecosystems are experiencing accelerating population and species loss. Some ecosystem functions are decreasing and there is growing interest in the link between biodiversity and ecosystem functioning. The role of cryptic (morphologically identical but genetically distinct) species in this biodiversity-ecosystem functioning link is unclear and has not yet been formally tested. We tested if there is a differential effect of four cryptic species of the bacterivorous nematode Litoditis marina on the decomposition process of macroalgae. Bacterivorous nematodes can stimulate or slow down bacterial activity and modify the bacterial assemblage composition. Moreover, we tested if interspecific interactions among the four cryptic species influence the decomposition process. A laboratory experiment with both mono- and multispecific nematode cultures was conducted, and loss of organic matter and the activity of two key extracellular enzymes for the degradation of phytodetritus were assessed. L. marina mainly influenced qualitative aspects of the decomposition process rather than its overall rate: an effect of the nematodes on the enzymatic activities became manifest, although no clear nematode effect on bulk organic matter weight loss was found. We also demonstrated that species-specific effects on the decomposition process existed. Combining the four cryptic species resulted in high competition, with one dominant species, but without complete exclusion of other species. These interspecific interactions translated into different effects on the decomposition process. The species-specific differences indicated that each cryptic species may play an important and distinct role in ecosystem functioning. Functional differences may result in coexistence among very similar species. PMID:27337962

  12. Vegetation ecology meets ecosystem science: Permanent grasslands as a functional biogeography case study.

    PubMed

    Violle, Cyrille; Choler, Philippe; Borgy, Benjamin; Garnier, Eric; Amiaud, Bernard; Debarros, Guilhem; Diquelou, Sylvain; Gachet, Sophie; Jolivet, Claudy; Kattge, Jens; Lavorel, Sandra; Lemauviel-Lavenant, Servane; Loranger, Jessy; Mikolajczak, Alexis; Munoz, François; Olivier, Jean; Viovy, Nicolas

    2015-11-15

    The effect of biodiversity on ecosystem functioning has been widely acknowledged, and the importance of the functional roles of species, as well as their diversity, in the control of ecosystem processes has been emphasised recently. However, bridging biodiversity and ecosystem science to address issues at a biogeographic scale is still in its infancy. Bridging this gap is the primary goal of the emerging field of functional biogeography. While the rise of Big Data has catalysed functional biogeography studies in recent years, comprehensive evidence remains scarce. Here, we present the rationale and the first results of a country-wide initiative focused on the C3 permanent grasslands. We aimed to collate, integrate and process large databases of vegetation relevés, plant traits and environmental layers to provide a country-wide assessment of ecosystem properties and services which can be used to improve regional models of climate and land use changes. We outline the theoretical background, data availability, and ecoinformatics challenges associated with the approach and its feasibility. We provide a case study of upscaling of leaf dry matter content averaged at ecosystem level and country-wide predictions of forage digestibility. Our framework sets milestones for further hypothesis testing in functional biogeography and earth system modelling. PMID:25908020

  13. Cryptic diversity and ecosystem functioning: a complex tale of differential effects on decomposition.

    PubMed

    De Meester, N; Gingold, R; Rigaux, A; Derycke, S; Moens, T

    2016-10-01

    Marine ecosystems are experiencing accelerating population and species loss. Some ecosystem functions are decreasing and there is growing interest in the link between biodiversity and ecosystem functioning. The role of cryptic (morphologically identical but genetically distinct) species in this biodiversity-ecosystem functioning link is unclear and has not yet been formally tested. We tested if there is a differential effect of four cryptic species of the bacterivorous nematode Litoditis marina on the decomposition process of macroalgae. Bacterivorous nematodes can stimulate or slow down bacterial activity and modify the bacterial assemblage composition. Moreover, we tested if interspecific interactions among the four cryptic species influence the decomposition process. A laboratory experiment with both mono- and multispecific nematode cultures was conducted, and loss of organic matter and the activity of two key extracellular enzymes for the degradation of phytodetritus were assessed. L. marina mainly influenced qualitative aspects of the decomposition process rather than its overall rate: an effect of the nematodes on the enzymatic activities became manifest, although no clear nematode effect on bulk organic matter weight loss was found. We also demonstrated that species-specific effects on the decomposition process existed. Combining the four cryptic species resulted in high competition, with one dominant species, but without complete exclusion of other species. These interspecific interactions translated into different effects on the decomposition process. The species-specific differences indicated that each cryptic species may play an important and distinct role in ecosystem functioning. Functional differences may result in coexistence among very similar species.

  14. Vegetation ecology meets ecosystem science: Permanent grasslands as a functional biogeography case study.

    PubMed

    Violle, Cyrille; Choler, Philippe; Borgy, Benjamin; Garnier, Eric; Amiaud, Bernard; Debarros, Guilhem; Diquelou, Sylvain; Gachet, Sophie; Jolivet, Claudy; Kattge, Jens; Lavorel, Sandra; Lemauviel-Lavenant, Servane; Loranger, Jessy; Mikolajczak, Alexis; Munoz, François; Olivier, Jean; Viovy, Nicolas

    2015-11-15

    The effect of biodiversity on ecosystem functioning has been widely acknowledged, and the importance of the functional roles of species, as well as their diversity, in the control of ecosystem processes has been emphasised recently. However, bridging biodiversity and ecosystem science to address issues at a biogeographic scale is still in its infancy. Bridging this gap is the primary goal of the emerging field of functional biogeography. While the rise of Big Data has catalysed functional biogeography studies in recent years, comprehensive evidence remains scarce. Here, we present the rationale and the first results of a country-wide initiative focused on the C3 permanent grasslands. We aimed to collate, integrate and process large databases of vegetation relevés, plant traits and environmental layers to provide a country-wide assessment of ecosystem properties and services which can be used to improve regional models of climate and land use changes. We outline the theoretical background, data availability, and ecoinformatics challenges associated with the approach and its feasibility. We provide a case study of upscaling of leaf dry matter content averaged at ecosystem level and country-wide predictions of forage digestibility. Our framework sets milestones for further hypothesis testing in functional biogeography and earth system modelling.

  15. New Insights on the Variability of Ecosystem Functioning Across Time Scales

    NASA Astrophysics Data System (ADS)

    Pappas, C.; Mahecha, M. D.; Frank, D. C.; Koutsoyiannis, D.

    2015-12-01

    Ecosystem functioning is monitored worldwide over several decades. However, a comparative in-depth characterization of the temporal variability of essential ecosystem processes, such as for example carbon assimilation and respiration is still lacking. The intra-annual (sub-diurnal, diurnal, and seasonal) variability of these processes can be well described by basic mechanisms such as the plant response to light. In contrast, the inter-annual variability and its origins and magnitude, remain highly uncertain. To date, there have only been a few attempts to investigate these issues across sites, ecosystems variables, and time scales, yet a general and comprehensive overview is outstanding. Here, we present a synthesis of a wide range of observations over Europe, namely: (i) eddy covariance measurements of carbon, energy, and water fluxes, (ii) satellite data of leaf area index and photosynthetically active radiation absorbed by plants, (iii) tree-ring widths, and (iv) dendrometer measurements of tree stem radius changes, and we analyze their variability from the half-hourly to the decadal time scale. Our analysis shows that all ecosystems can be characterized by three distinct regimes of variability (sub-daily, daily-seasonal, and seasonal-annual) confined within the ranges of the available resources, i.e., water (precipitation) and energy (radiation and temperature). We find a convergence of the range of variability of hydrometeorological drivers. Surprisingly, such convergence is not reflected in the variability of the ecosystem responses across sites. Although the magnitude of variability of ecosystem functioning varies across sites, the temporal dependences present the same characteristics over time scales spanning five orders of magnitude. We show that this behaviour can be well simulated by combining simple stochastic models with deterministic harmonics (diurnal and annual cycles). This allows us to statistically characterize the short- and long

  16. Effects of drought and irrigation on ecosystem functioning in a mature Scots pine forest

    NASA Astrophysics Data System (ADS)

    Dobbertin, Matthias; Brunner, Ivano; Egli, Simon; Eilmann, Britta; Graf Pannatier, Eisabeth; Schleppi, Patrick; Zingg, Andreas; Rigling, Andreas

    2010-05-01

    . Soil water content was significantly reduced during irrigation periods. Irrigation doubled tree stem growth, increased shoot growth and thus increased volume growth and crown dimensions. Annual tree mortality rates were reduced by 50% in irrigated plots. The growing period for stem growth was extended in pines as a result of irrigation. Altogether, increased growth and reduced mortality significantly increased tree stem basal area at breast height per ha. As irrigation also increased needle length, estimated mean foliage amount per tree and stand leaf area index significantly increased. However, the number of needle generations was not altered or even reduced due to irrigation. Root growth, was less affected by irrigation and only resulted in increased fine root length. Species richness and fruit body numbers of mycorrhizal fungi were several times higher on the irrigated plots. Overall, it can be concluded that water availability was the main ecosystem limiting factor and that any changes in water availability will result in changes in ecosystem functioning. References Brunner I, Graf-Pannatier E, Frey B, Rigling A, Landolt W, Dobbertin M (2009) Morphological and physiological responses of Scots pine fine roots to water supply in a climatic dry area in Switzerland. Tree Physiology 29:541-550. Dobbertin M, Eilmann B, Bleuler P, Giuggiola A, Graf Pannatier E, Landolt W, Schleppi P, Rigling A (2010) Effect of irrigation on needle, shoot and stem growth in natural drought-exposed Pinus sylvestris forests, Tree Physiology, doi:10.1093/treephys/tpp123. Eilmann B, Zweifel R, Buchmann N, Fonti P, Rigling A (2009) Drought induced adaptation of the xylem in Pinus sylvestris and Quercus pubescens. Tree Physiology 29:1011-1020.

  17. Trophic complexity enhances ecosystem functioning in an aquatic detritus-based model system.

    PubMed

    Jabiol, Jérémy; McKie, Brendan G; Bruder, Andreas; Bernadet, Caroline; Gessner, Mark O; Chauvet, Eric

    2013-09-01

    1. Understanding the functional significance of species interactions in ecosystems has become a major challenge as biodiversity declines rapidly worldwide. Ecosystem consequences arising from the loss of diversity either within trophic levels (horizontal diversity) or across trophic levels (vertical diversity) are well documented. However, simultaneous losses of species at different trophic levels may also result in interactive effects, with potentially complex outcomes for ecosystem functioning. 2. Because of logistical constraints, the outcomes of such interactions have been difficult to assess in experiments involving large metazoan species. Here, we take advantage of a detritus-based model system to experimentally assess the consequences of biodiversity change within both horizontal and vertical food-web components on leaf-litter decomposition, a fundamental process in a wide range of ecosystems. 3. Our concurrent manipulation of fungal decomposer diversity (0, 1 or 5 species), detritivore diversity (0, 1 or 3 species), and the presence of predatory fish scent showed that trophic complexity is key to eliciting diversity effects on ecosystem functioning. Specifically, although fungi and detritivores tended to promote decomposition individually, rates were highest in the most complete community where all trophic levels were represented at the highest possible species richness. In part, the effects were trait-mediated, reflected in the contrasting foraging responses of the detritivore species to predator scent. 4. Our results thus highlight the importance of interactive effects of simultaneous species loss within multiple trophic levels on ecosystem functioning. If a common phenomenon, this outcome suggests that functional ecosystem impairment resulting from widespread biodiversity loss could be more severe than inferred from previous experiments confined to varying diversity within single trophic levels.

  18. Effects of roads on adjacent plant community composition and ecosystem function: An example from three calcareous ecosystems.

    PubMed

    Lee, Mark A; Davies, Linda; Power, Sally A

    2012-04-01

    Roads and exhaust emissions can affect plant communities directly, for example via direct foliar uptake of exhaust products, or indirectly via changes to soil biogeochemistry and hydrology. A transect study adjacent to roads of different traffic densities was carried out at three species-rich calcareous grasslands in south eastern England. Measured annual NO(2) concentrations and modelled NH(3) concentrations increased towards the roads and with higher traffic densities, and there was evidence of increased soil moisture, pH and heavy metal concentrations at roadsides. Increases in the abundance of nitrogen (N) tolerant species and grasses at roadsides were associated with N enrichment from vehicle exhausts at two of the sites. In contrast plant species richness, the abundance of forb and moss species declined at roadside locations. As vehicle usage spreads across the world, it is increasingly important to understand the effects of road traffic on adjacent ecosystems to inform traffic and conservation management policies.

  19. When does diversity matter? Species functional diversity and ecosystem functioning across habitats and seasons in a field experiment.

    PubMed

    Frainer, André; McKie, Brendan G; Malmqvist, Björn

    2014-03-01

    Despite ample experimental evidence indicating that biodiversity might be an important driver of ecosystem processes, its role in the functioning of real ecosystems remains unclear. In particular, the understanding of which aspects of biodiversity are most important for ecosystem functioning, their importance relative to other biotic and abiotic drivers, and the circumstances under which biodiversity is most likely to influence functioning in nature, is limited. We conducted a field study that focussed on a guild of insect detritivores in streams, in which we quantified variation in the process of leaf decomposition across two habitats (riffles and pools) and two seasons (autumn and spring). The study was conducted in six streams, and the same locations were sampled in the two seasons. With the aid of structural equations modelling, we assessed spatiotemporal variation in the roles of three key biotic drivers in this process: functional diversity, quantified based on a species trait matrix, consumer density and biomass. Our models also accounted for variability related to different litter resources, and other sources of biotic and abiotic variability among streams. All three of our focal biotic drivers influenced leaf decomposition, but none was important in all habitats and seasons. Functional diversity had contrasting effects on decomposition between habitats and seasons. A positive relationship was observed in pool habitats in spring, associated with high trait dispersion, whereas a negative relationship was observed in riffle habitats during autumn. Our results demonstrate that functional biodiversity can be as significant for functioning in natural ecosystems as other important biotic drivers. In particular, variation in the role of functional diversity between seasons highlights the importance of fluctuations in the relative abundances of traits for ecosystem process rates in real ecosystems.

  20. Ammonium as a Driving Force of Plant Diversity and Ecosystem Functioning: Observations Based on 5 Years' Manipulation of N Dose and Form in a Mediterranean Ecosystem

    PubMed Central

    Dias, Teresa; Clemente, Adelaide; Martins-Loução, Maria Amélia; Sheppard, Lucy; Bobbink, Roland; Cruz, Cristina

    2014-01-01

    Enhanced nitrogen (N) availability is one of the main drivers of biodiversity loss and degradation of ecosystem functions. However, in very nutrient-poor ecosystems, enhanced N input can, in the short-term, promote diversity. Mediterranean Basin ecosystems are nutrient-limited biodiversity hotspots, but no information is available on their medium- or long-term responses to enhanced N input. Since 2007, we have been manipulating the form and dose of available N in a Mediterranean Basin maquis in south-western Europe that has low ambient N deposition (<4 kg N ha−1 yr−1) and low soil N content (0.1%). N availability was modified by the addition of 40 kg N ha−1 yr−1 as a 1∶1 NH4Cl to (NH4)2SO4 mixture, and 40 and 80 kg N ha−1 yr−1 as NH4NO3. Over the following 5 years, the impacts on plant composition and diversity (richness and evenness) and some ecosystem characteristics (soil extractable N and organic matter, aboveground biomass and % of bare soil) were assessed. Plant species richness increased with enhanced N input and was more related to ammonium than to nitrate. Exposure to 40 kg NH4+-N ha−1 yr−1 (alone and with nitrate) enhanced plant richness, but did not increase aboveground biomass; soil extractable N even increased under 80 kg NH4NO3-N ha−1 yr−1 and the % of bare soil increased under 40 kg NH4+-N ha−1 yr−1. The treatment containing less ammonium, 40 kg NH4NO3-N ha−1 yr−1, did not enhance plant diversity but promoted aboveground biomass and reduced the % of bare soil. Data suggest that enhanced NHy availability affects the structure of the maquis, which may promote soil erosion and N leakage, whereas enhanced NOx availability leads to biomass accumulation which may increase the fire risk. These observations are relevant for land use management in biodiverse and fragmented ecosystems such as the maquis, especially in conservation areas. PMID:24695101

  1. Microtopographic controls on ecosystem functioning in the Arctic Coastal Plain

    NASA Astrophysics Data System (ADS)

    Zona, D.; Lipson, D. A.; Zulueta, R. C.; Oberbauer, S. F.; Oechel, W. C.

    2011-12-01

    The investigation of the microtopographic controls on thermal and hydrologic conditions of the soil and consequently the carbon dynamics from Arctic regions is of major importance. Ecosystem respiration (ER) between microsites of the same tundra type could differ more than ER in different tundra types even at different latitudes. In this study we investigated the microtopographic effect on soil temperature, thaw depth, pH, oxidation reduction potential (ORP), electrical conductivity (EC), dissolved CO2, vegetation types, and ER rates from different features forming the low-center polygon structure. Most of these environmental variables significantly differ particularly between areas with higher elevation (polygon rims) and with lower elevation (low-center polygons). Polygon rims presented the lowest water table and showed the lowest thaw depth and the highest ER (a seasonal average of 1 μmol CO2 m-2 s-1), almost double than the ER in the low-center polygons (a seasonal average of 0.6 μmol CO2 m-2 s-1). The microtopographic gradient from polygon rims to low-centers led to a very consistent pattern in pH, EC, ORP and dissolved CO2, with low-centers presenting the highest pH, the highest EC, the highest dissolved CO2, and the lowest ORP. Based on vegetation measurements, we also showed that microtopography controls the lateral flow of organic matter, and that vascular plant material accumulates as litter in the lower elevation areas, possibly contributing to the higher dissolved CO2 in the low-center polygons. Microtopography, and the ramifications discussed here, should be considered when evaluating landscape scale environmental controls on carbon dynamics in the Arctic.

  2. The Relevance of Marine Chemical Ecology to Plankton and Ecosystem Function: An Emerging Field

    PubMed Central

    Ianora, Adrianna; Bentley, Matthew G.; Caldwell, Gary S.; Casotti, Raffaella; Cembella, Allan D.; Engström-Öst, Jonna; Halsband, Claudia; Sonnenschein, Eva; Legrand, Catherine; Llewellyn, Carole A.; Paldavičienë, Aistë; Pilkaityte, Renata; Pohnert, Georg; Razinkovas, Arturas; Romano, Giovanna; Tillmann, Urban; Vaiciute, Diana

    2011-01-01

    Marine chemical ecology comprises the study of the production and interaction of bioactive molecules affecting organism behavior and function. Here we focus on bioactive compounds and interactions associated with phytoplankton, particularly bloom-forming diatoms, prymnesiophytes and dinoflagellates. Planktonic bioactive metabolites are structurally and functionally diverse and some may have multiple simultaneous functions including roles in chemical defense (antipredator, allelopathic and antibacterial compounds), and/or cell-to-cell signaling (e.g., polyunsaturated aldehydes (PUAs) of diatoms). Among inducible chemical defenses in response to grazing, there is high species-specific variability in the effects on grazers, ranging from severe physical incapacitation and/or death to no apparent physiological response, depending on predator susceptibility and detoxification capability. Most bioactive compounds are present in very low concentrations, in both the producing organism and the surrounding aqueous medium. Furthermore, bioactivity may be subject to synergistic interactions with other natural and anthropogenic environmental toxicants. Most, if not all phycotoxins are classic secondary metabolites, but many other bioactive metabolites are simple molecules derived from primary metabolism (e.g., PUAs in diatoms, dimethylsulfoniopropionate (DMSP) in prymnesiophytes). Producing cells do not seem to suffer physiological impact due to their synthesis. Functional genome sequence data and gene expression analysis will provide insights into regulatory and metabolic pathways in producer organisms, as well as identification of mechanisms of action in target organisms. Understanding chemical ecological responses to environmental triggers and chemically-mediated species interactions will help define crucial chemical and molecular processes that help maintain biodiversity and ecosystem functionality. PMID:22131962

  3. Links between plant litter chemistry, species diversity, and below-ground ecosystem function.

    PubMed

    Meier, Courtney L; Bowman, William D

    2008-12-16

    Decomposition is a critical source of plant nutrients, and drives the largest flux of terrestrial C to the atmosphere. Decomposing soil organic matter typically contains litter from multiple plant species, yet we lack a mechanistic understanding of how species diversity influences decomposition processes. Here, we show that soil C and N cycling during decomposition are controlled by the composition and diversity of chemical compounds within plant litter mixtures, rather than by simple metrics of plant species diversity. We amended native soils with litter mixtures containing up to 4 alpine plant species, and we used 9 litter chemical traits to evaluate the chemical composition (i.e., the identity and quantity of compounds) and chemical diversity of the litter mixtures. The chemical composition of the litter mixtures was the strongest predictor of soil respiration, net N mineralization, and microbial biomass N. Soil respiration and net N mineralization rates were also significantly correlated with the chemical diversity of the litter mixtures. In contrast, soil C and N cycling rates were poorly correlated with plant species richness, and there was no relationship between species richness and the chemical diversity of the litter mixtures. These results indicate that the composition and diversity of chemical compounds in litter are potentially important functional traits affecting decomposition, and simple metrics like plant species richness may fail to capture variation in these traits. Litter chemical traits therefore provide a mechanistic link between organisms, species diversity, and key components of below-ground ecosystem function.

  4. Water ecosystem service function assessment based on eco-hydrological process in Luanhe Basin,China

    NASA Astrophysics Data System (ADS)

    Zhang, C.; Hao, C.; Qin, T.; Wang, G.; Weng, B.

    2012-12-01

    At present, ecological water are mainly occupied by a rapid development of social economic and population explosion, which seriously threat the ecological security and water security in watershed and regional scale. Due to the lack of a unified standard of measuring the benefit of water resource, social economic and ecosystem, the water allocation can't take place in social economic and ecosystem. The function which provided by water in terrestrial, aquatic and social economic system can be addressed through water ecosystem service function research, and it can guide the water allocation in water resource management. The function which provided by water in terrestrial, aquatic and social economic system can be addressed through water ecosystem service function research, and it can guide the water allocation in water resource management. Throughout the researches of water ecosystem service, a clear identification of the connection of water ecosystem service function has not been established, and eco-economic approach can't meet the practical requirement of water allocation. Based on "nature-artificiality" dual water cycle theory and eco-hydrological process, this paper proposes a connection and indicator system of water ecosystem service function. In approach, this paper establishes an integrated assessment approach through prototype observation technology, numerical simulation, physical simulation and modern geographic information technology. The core content is to couple an eco-hydrological model, which involves the key processes of distributed hydrological model (WEP), ecological model (CLM-DGVM), in terms of eco-hydrological process. This paper systematically evaluates the eco-hydrological process and evolution of Luanhe Basin in terms of precipitation, ET, runoff, groundwater, ecosystem's scale, form and distribution. According to the results of eco-hydrological process, this paper assesses the direct and derived service function. The result indicates that the

  5. Tropical Marginal Seas: Priority Regions for Managing Marine Biodiversity and Ecosystem Function

    NASA Astrophysics Data System (ADS)

    McKinnon, A. David; Williams, Alan; Young, Jock; Ceccarelli, Daniela; Dunstan, Piers; Brewin, Robert J. W.; Watson, Reg; Brinkman, Richard; Cappo, Mike; Duggan, Samantha; Kelley, Russell; Ridgway, Ken; Lindsay, Dhugal; Gledhill, Daniel; Hutton, Trevor; Richardson, Anthony J.

    2014-01-01

    Tropical marginal seas (TMSs) are natural subregions of tropical oceans containing biodiverse ecosystems with conspicuous, valued, and vulnerable biodiversity assets. They are focal points for global marine conservation because they occur in regions where human populations are rapidly expanding. Our review of 11 TMSs focuses on three key ecosystems - coral reefs and emergent atolls, deep benthic systems, and pelagic biomes - and synthesizes, illustrates, and contrasts knowledge of biodiversity, ecosystem function, interaction between adjacent habitats, and anthropogenic pressures. TMSs vary in the extent that they have been subject to human influence - from the nearly pristine Coral Sea to the heavily exploited South China and Caribbean Seas - but we predict that they will all be similarly complex to manage because most span multiple national jurisdictions. We conclude that developing a structured process to identify ecologically and biologically significant areas that uses a set of globally agreed criteria is a tractable first step toward effective multinational and transboundary ecosystem management of TMSs.

  6. Tropical marginal seas: priority regions for managing marine biodiversity and ecosystem function.

    PubMed

    McKinnon, A David; Williams, Alan; Young, Jock; Ceccarelli, Daniela; Dunstan, Piers; Brewin, Robert J W; Watson, Reg; Brinkman, Richard; Cappo, Mike; Duggan, Samantha; Kelley, Russell; Ridgway, Ken; Lindsay, Dhugal; Gledhill, Daniel; Hutton, Trevor; Richardson, Anthony J

    2014-01-01

    Tropical marginal seas (TMSs) are natural subregions of tropical oceans containing biodiverse ecosystems with conspicuous, valued, and vulnerable biodiversity assets. They are focal points for global marine conservation because they occur in regions where human populations are rapidly expanding. Our review of 11 TMSs focuses on three key ecosystems-coral reefs and emergent atolls, deep benthic systems, and pelagic biomes-and synthesizes, illustrates, and contrasts knowledge of biodiversity, ecosystem function, interaction between adjacent habitats, and anthropogenic pressures. TMSs vary in the extent that they have been subject to human influence-from the nearly pristine Coral Sea to the heavily exploited South China and Caribbean Seas-but we predict that they will all be similarly complex to manage because most span multiple national jurisdictions. We conclude that developing a structured process to identify ecologically and biologically significant areas that uses a set of globally agreed criteria is a tractable first step toward effective multinational and transboundary ecosystem management of TMSs.

  7. Effects of Trophic Skewing of Species Richness on Ecosystem Functioning in a Diverse Marine Community

    PubMed Central

    Reynolds, Pamela L.; Bruno, John F.

    2012-01-01

    Widespread overharvesting of top consumers of the world’s ecosystems has “skewed” food webs, in terms of biomass and species richness, towards a generally greater domination at lower trophic levels. This skewing is exacerbated in locations where exotic species are predominantly low-trophic level consumers such as benthic macrophytes, detritivores, and filter feeders. However, in some systems where numerous exotic predators have been added, sometimes purposefully as in many freshwater systems, food webs are skewed in the opposite direction toward consumer dominance. Little is known about how such modifications to food web topology, e.g., changes in the ratio of predator to prey species richness, affect ecosystem functioning. We experimentally measured the effects of trophic skew on production in an estuarine food web by manipulating ratios of species richness across three trophic levels in experimental mesocosms. After 24 days, increasing macroalgal richness promoted both plant biomass and grazer abundance, although the positive effect on plant biomass disappeared in the presence of grazers. The strongest trophic cascade on the experimentally stocked macroalgae emerged in communities with a greater ratio of prey to predator richness (bottom-rich food webs), while stronger cascades on the accumulation of naturally colonizing algae (primarily microalgae with some early successional macroalgae that recruited and grew in the mesocosms) generally emerged in communities with greater predator to prey richness (the more top-rich food webs). These results suggest that trophic skewing of species richness and overall changes in food web topology can influence marine community structure and food web dynamics in complex ways, emphasizing the need for multitrophic approaches to understand the consequences of marine extinctions and invasions. PMID:22693549

  8. Effects of trophic skewing of species richness on ecosystem functioning in a diverse marine community.

    PubMed

    Reynolds, Pamela L; Bruno, John F

    2012-01-01

    Widespread overharvesting of top consumers of the world's ecosystems has "skewed" food webs, in terms of biomass and species richness, towards a generally greater domination at lower trophic levels. This skewing is exacerbated in locations where exotic species are predominantly low-trophic level consumers such as benthic macrophytes, detritivores, and filter feeders. However, in some systems where numerous exotic predators have been added, sometimes purposefully as in many freshwater systems, food webs are skewed in the opposite direction toward consumer dominance. Little is known about how such modifications to food web topology, e.g., changes in the ratio of predator to prey species richness, affect ecosystem functioning. We experimentally measured the effects of trophic skew on production in an estuarine food web by manipulating ratios of species richness across three trophic levels in experimental mesocosms. After 24 days, increasing macroalgal richness promoted both plant biomass and grazer abundance, although the positive effect on plant biomass disappeared in the presence of grazers. The strongest trophic cascade on the experimentally stocked macroalgae emerged in communities with a greater ratio of prey to predator richness (bottom-rich food webs), while stronger cascades on the accumulation of naturally colonizing algae (primarily microalgae with some early successional macroalgae that recruited and grew in the mesocosms) generally emerged in communities with greater predator to prey richness (the more top-rich food webs). These results suggest that trophic skewing of species richness and overall changes in food web topology can influence marine community structure and food web dynamics in complex ways, emphasizing the need for multitrophic approaches to understand the consequences of marine extinctions and invasions.

  9. Distribution, structure and function of Nordic eelgrass (Zostera marina) ecosystems: implications for coastal management and conservation

    PubMed Central

    Boström, Christoffer; Baden, Susanne; Bockelmann, Anna-Christina; Dromph, Karsten; Fredriksen, Stein; Gustafsson, Camilla; Krause-Jensen, Dorte; Möller, Tiia; Nielsen, Søren Laurentius; Olesen, Birgit; Olsen, Jeanine; Pihl, Leif; Rinde, Eli

    2014-01-01

    This paper focuses on the marine foundation eelgrass species, Zostera marina, along a gradient from the northern Baltic Sea to the north-east Atlantic. This vast region supports a minimum of 1480 km2 eelgrass (maximum >2100 km2), which corresponds to more than four times the previously quantified area of eelgrass in Western Europe.Eelgrass meadows in the low salinity Baltic Sea support the highest diversity (4–6 spp.) of angiosperms overall, but eelgrass productivity is low (<2 g dw m-2 d-1) and meadows are isolated and genetically impoverished. Higher salinity areas support monospecific meadows, with higher productivity (3–10 g dw m-2 d-1) and greater genetic connectivity. The salinity gradient further imposes functional differences in biodiversity and food webs, in particular a decline in number, but increase in biomass of mesograzers in the Baltic.Significant declines in eelgrass depth limits and areal cover are documented, particularly in regions experiencing high human pressure. The failure of eelgrass to re-establish itself in affected areas, despite nutrient reductions and improved water quality, signals complex recovery trajectories and calls for much greater conservation effort to protect existing meadows.The knowledge base for Nordic eelgrass meadows is broad and sufficient to establish monitoring objectives across nine national borders. Nevertheless, ensuring awareness of their vulnerability remains challenging. Given the areal extent of Nordic eelgrass systems and the ecosystem services they provide, it is crucial to further develop incentives for protecting them. © 2014 The Authors. Aquatic Conservation: Marine and Freshwater Ecosystems published by John Wiley & Sons, Ltd. PMID:26167100

  10. Using the CARDAMOM framework to retrieve global terrestrial ecosystem functioning properties

    NASA Astrophysics Data System (ADS)

    Exbrayat, Jean-François; Bloom, A. Anthony; Smallman, T. Luke; van der Velde, Ivar R.; Feng, Liang; Williams, Mathew

    2016-04-01

    Terrestrial ecosystems act as a sink for anthropogenic emissions of fossil-fuel and thereby partially offset the ongoing global warming. However, recent model benchmarking and intercomparison studies have highlighted the non-trivial uncertainties that exist in our understanding of key ecosystem properties like plant carbon allocation and residence times. It leads to worrisome differences in terrestrial carbon stocks simulated by Earth system models, and their evolution in a warming future. In this presentation we attempt to provide global insights on these properties by merging an ecosystem model with remotely-sensed global observations of leaf area and biomass through a data-assimilation system: the CARbon Data MOdel fraMework (CARDAMOM). CARDAMOM relies on a Markov Chain Monte Carlo algorithm to retrieve confidence intervals of model parameters that regulate ecosystem properties independently of any prior land-cover information. The MCMC method thereby enables an explicit representation of the uncertainty in land-atmosphere fluxes and the evolution of terrestrial carbon stocks through time. Global experiments are performed for the first decade of the 21st century using a 1°×1° spatial resolution. Relationships emerge globally between key ecosystem properties. For example, our analyses indicate that leaf lifespan and leaf mass per area are highly correlated. Furthermore, there exists a latitudinal gradient in allocation patterns: high latitude ecosystems allocate more carbon to photosynthetic carbon (leaves) while plants invest more carbon in their structural parts (wood and root) in the wet tropics. Overall, the spatial distribution of these ecosystem properties does not correspond to usual land-cover maps and are also partially correlated with disturbance regimes. For example, fire-prone ecosystems present statistically significant higher values of carbon use efficiency than less disturbed ecosystems experiencing similar climatic conditions. These results

  11. Using a multi-trait approach to manipulate plant functional diversity in a biodiversity-ecosystem function experiment.

    PubMed

    Schittko, Conrad; Hawa, Mahmoud; Wurst, Susanne

    2014-01-01

    A frequent pattern emerging from biodiversity-ecosystem function studies is that functional group richness enhances ecosystem functions such as primary productivity. However, the manipulation of functional group richness goes along with major disadvantages like the transformation of functional trait data into categories or the exclusion of functional differences between organisms in the same group. In a mesocosm study we manipulated plant functional diversity based on the multi-trait Functional Diversity (FD)-approach of Petchey and Gaston by using database data of seven functional traits and information on the origin of the species in terms of being native or exotic. Along a gradient ranging from low to high FD we planted 40 randomly selected eight-species mixtures under controlled conditions. We found a significant positive linear correlation of FD with aboveground productivity and a negative correlation with invasibility of the plant communities. Based on community-weighted mean calculations for each functional trait, we figured out that the traits N-fixation and species origin, i.e. being native or exotic, played the most important role for community productivity. Our results suggest that the identification of the impact of functional trait diversity and the relative contributions of relevant traits is essential for a mechanistic understanding of the role of biodiversity for ecosystem functions such as aboveground biomass production and resistance against invasion.

  12. Using a Multi-Trait Approach to Manipulate Plant Functional Diversity in a Biodiversity-Ecosystem Function Experiment

    PubMed Central

    Schittko, Conrad; Hawa, Mahmoud; Wurst, Susanne

    2014-01-01

    A frequent pattern emerging from biodiversity-ecosystem function studies is that functional group richness enhances ecosystem functions such as primary productivity. However, the manipulation of functional group richness goes along with major disadvantages like the transformation of functional trait data into categories or the exclusion of functional differences between organisms in the same group. In a mesocosm study we manipulated plant functional diversity based on the multi-trait Functional Diversity (FD)-approach of Petchey and Gaston by using database data of seven functional traits and information on the origin of the species in terms of being native or exotic. Along a gradient ranging from low to high FD we planted 40 randomly selected eight-species mixtures under controlled conditions. We found a significant positive linear correlation of FD with aboveground productivity and a negative correlation with invasibility of the plant communities. Based on community-weighted mean calculations for each functional trait, we figured out that the traits N-fixation and species origin, i.e. being native or exotic, played the most important role for community productivity. Our results suggest that the identification of the impact of functional trait diversity and the relative contributions of relevant traits is essential for a mechanistic understanding of the role of biodiversity for ecosystem functions such as aboveground biomass production and resistance against invasion. PMID:24897501

  13. Using a multi-trait approach to manipulate plant functional diversity in a biodiversity-ecosystem function experiment.

    PubMed

    Schittko, Conrad; Hawa, Mahmoud; Wurst, Susanne

    2014-01-01

    A frequent pattern emerging from biodiversity-ecosystem function studies is that functional group richness enhances ecosystem functions such as primary productivity. However, the manipulation of functional group richness goes along with major disadvantages like the transformation of functional trait data into categories or the exclusion of functional differences between organisms in the same group. In a mesocosm study we manipulated plant functional diversity based on the multi-trait Functional Diversity (FD)-approach of Petchey and Gaston by using database data of seven functional traits and information on the origin of the species in terms of being native or exotic. Along a gradient ranging from low to high FD we planted 40 randomly selected eight-species mixtures under controlled conditions. We found a significant positive linear correlation of FD with aboveground productivity and a negative correlation with invasibility of the plant communities. Based on community-weighted mean calculations for each functional trait, we figured out that the traits N-fixation and species origin, i.e. being native or exotic, played the most important role for community productivity. Our results suggest that the identification of the impact of functional trait diversity and the relative contributions of relevant traits is essential for a mechanistic understanding of the role of biodiversity for ecosystem functions such as aboveground biomass production and resistance against invasion. PMID:24897501

  14. Key role in ecosystem functioning of scavengers reliant on a single common species.

    PubMed

    Inger, Richard; Per, Esra; Cox, Daniel T C; Gaston, Kevin J

    2016-07-12

    The importance of species richness in maintaining ecosystem function in the field remains unclear. Recent studies however have suggested that in some systems functionality is maintained by a few abundant species. Here we determine this relationship by quantifying the species responsible for a key ecosystem role, carcass removal by scavengers. We find that, unlike those within largely unaltered environments, the scavenger community within our highly altered system is dominated by a single species, the Carrion crow, despite the presence of a number of other scavenging species. Furthermore, we find no relationship between abundance of crows and carcass removal. However, the overall activity of crows predicts carcass biomass removal rate in an asymptotic manner, suggesting that a relatively low level of abundance and scavenging activity is required to maintain this component of ecosystem function.

  15. Key role in ecosystem functioning of scavengers reliant on a single common species

    PubMed Central

    Inger, Richard; Per, Esra; Cox, Daniel T.C.; Gaston, Kevin J.

    2016-01-01

    The importance of species richness in maintaining ecosystem function in the field remains unclear. Recent studies however have suggested that in some systems functionality is maintained by a few abundant species. Here we determine this relationship by quantifying the species responsible for a key ecosystem role, carcass removal by scavengers. We find that, unlike those within largely unaltered environments, the scavenger community within our highly altered system is dominated by a single species, the Carrion crow, despite the presence of a number of other scavenging species. Furthermore, we find no relationship between abundance of crows and carcass removal. However, the overall activity of crows predicts carcass biomass removal rate in an asymptotic manner, suggesting that a relatively low level of abundance and scavenging activity is required to maintain this component of ecosystem function. PMID:27404915

  16. Predicting climate change effects on wetland ecosystem services using species distribution modeling and plant functional traits.

    PubMed

    Moor, Helen; Hylander, Kristoffer; Norberg, Jon

    2015-01-01

    Wetlands provide multiple ecosystem services, the sustainable use of which requires knowledge of the underlying ecological mechanisms. Functional traits, particularly the community-weighted mean trait (CWMT), provide a strong link between species communities and ecosystem functioning. We here combine species distribution modeling and plant functional traits to estimate the direction of change of ecosystem processes under climate change. We model changes in CWMT values for traits relevant to three key services, focusing on the regional species pool in the Norrström area (central Sweden) and three main wetland types. Our method predicts proportional shifts toward faster growing, more productive and taller species, which tend to increase CWMT values of specific leaf area and canopy height, whereas changes in root depth vary. The predicted changes in CWMT values suggest a potential increase in flood attenuation services, a potential increase in short (but not long)-term nutrient retention, and ambiguous outcomes for carbon sequestration.

  17. Key role in ecosystem functioning of scavengers reliant on a single common species.

    PubMed

    Inger, Richard; Per, Esra; Cox, Daniel T C; Gaston, Kevin J

    2016-01-01

    The importance of species richness in maintaining ecosystem function in the field remains unclear. Recent studies however have suggested that in some systems functionality is maintained by a few abundant species. Here we determine this relationship by quantifying the species responsible for a key ecosystem role, carcass removal by scavengers. We find that, unlike those within largely unaltered environments, the scavenger community within our highly altered system is dominated by a single species, the Carrion crow, despite the presence of a number of other scavenging species. Furthermore, we find no relationship between abundance of crows and carcass removal. However, the overall activity of crows predicts carcass biomass removal rate in an asymptotic manner, suggesting that a relatively low level of abundance and scavenging activity is required to maintain this component of ecosystem function. PMID:27404915

  18. Herbivore species richness and feeding complementarity affect community structure and function on a coral reef

    PubMed Central

    Burkepile, Deron E.; Hay, Mark E.

    2008-01-01

    Consumer effects on prey are well known for cascading through food webs and producing dramatic top-down effects on community structure and ecosystem function. Bottom-up effects of prey (primary producer) biodiversity are also well known. However, the role of consumer diversity in affecting community structure or ecosystem function is not well understood. Here, we show that herbivore species richness can be critical for maintaining the structure and function of coral reefs. In two experiments over 2 years, we constructed large cages enclosing single herbivore species, equal densities of mixed species of herbivores, or excluding herbivores and assessed effects on both seaweeds and corals. When compared with single-herbivore treatments, mixed-herbivore treatments lowered macroalgal abundance by 54–76%, enhanced cover of crustose coralline algae (preferred recruitment sites for corals) by 52–64%, increased coral cover by 22%, and prevented coral mortality. Complementary feeding by herbivorous fishes drove the herbivore richness effects, because macroalgae were unable to effectively deter fishes with different feeding strategies. Maintaining herbivore species richness appears critical for preserving coral reefs, because complementary feeding by diverse herbivores produces positive, but indirect, effects on corals, the foundation species for the ecosystem. PMID:18845686

  19. How a clogged canal affects ecological and human health in a tropical urban wetland ecosystem

    EPA Science Inventory

    The coastal city of San Juan, Puerto Rico is a tropical urban ecosystem woven among a series of interconnected bays, lagoons, drains, canals, and mangroves. As the city has expanded, infilling and urban development by the region’s poorest residents has choked an important c...

  20. Macroecological scale effects of biodiversity on ecosystem functions under environmental change.

    PubMed

    Burley, Hugh M; Mokany, Karel; Ferrier, Simon; Laffan, Shawn W; Williams, Kristen J; Harwood, Tom D

    2016-04-01

    Conserving different spatial and temporal dimensions of biological diversity is considered necessary for maintaining ecosystem functions under predicted global change scenarios. Recent work has shifted the focus from spatially local (α-diversity) to macroecological scales (β- and γ-diversity), emphasizing links between macroecological biodiversity and ecosystem functions (MB-EF relationships). However, before the outcomes of MB-EF analyses can be useful to real-world decisions, empirical modeling needs to be developed for natural ecosystems, incorporating a broader range of data inputs, environmental change scenarios, underlying mechanisms, and predictions. We outline the key conceptual and technical challenges currently faced in developing such models and in testing and calibrating the relationships assumed in these models using data from real ecosystems. These challenges are explored in relation to two potential MB-EF mechanisms: "macroecological complementarity" and "spatiotemporal compensation." Several regions have been sufficiently well studied over space and time to robustly test these mechanisms by combining cutting-edge spatiotemporal methods with remotely sensed data, including plant community data sets in Australia, Europe, and North America. Assessing empirical MB-EF relationships at broad spatiotemporal scales will be crucial in ensuring these macroecological processes can be adequately considered in the management of biodiversity and ecosystem functions under global change. PMID:27066246

  1. Body size as a predictor of species loss effect on ecosystem functioning.

    PubMed

    Séguin, Annie; Harvey, Éric; Archambault, Philippe; Nozais, Christian; Gravel, Dominique

    2014-04-09

    There is an urgent need to develop predictive indicators of the effect of species loss on ecosystem functioning. Body size is often considered as a good indicator because of its relationship to extinction risk and several functional traits. Here, we examined the predictive capacity of species body size in marine and freshwater multitrophic systems. We found a significant, but weak, effect of body size on functioning. The effect was much stronger when considering the effect of body size within trophic position levels. Compared to extinctions ordered by body size, random extinction sequences had lower multiple species loss effects on functioning. Our study is the first to show experimentally, in multitrophic systems, a more negative impact of ordered extinction sequences on ecosystem functioning than random losses. Our results suggest apparent ease in predicting species loss effect on functioning based on easily measured ecological traits that are body size and trophic position.

  2. Body size as a predictor of species loss effect on ecosystem functioning

    PubMed Central

    Séguin, Annie; Harvey, Éric; Archambault, Philippe; Nozais, Christian; Gravel, Dominique

    2014-01-01

    There is an urgent need to develop predictive indicators of the effect of species loss on ecosystem functioning. Body size is often considered as a good indicator because of its relationship to extinction risk and several functional traits. Here, we examined the predictive capacity of species body size in marine and freshwater multitrophic systems. We found a significant, but weak, effect of body size on functioning. The effect was much stronger when considering the effect of body size within trophic position levels. Compared to extinctions ordered by body size, random extinction sequences had lower multiple species loss effects on functioning. Our study is the first to show experimentally, in multitrophic systems, a more negative impact of ordered extinction sequences on ecosystem functioning than random losses. Our results suggest apparent ease in predicting species loss effect on functioning based on easily measured ecological traits that are body size and trophic position. PMID:24714619

  3. Impacts of climate variability on functional diversity and species distribution in dryland ecosystems

    NASA Astrophysics Data System (ADS)

    Caylor, K. K.; Franz, T.

    2008-12-01

    The role rainfall heterogeneity is an important but poorly understood aspect of ecosystem function in dryland communities. While general relationships between annual rainfall and tree cover have been revealed through meta-analysis and inter-site comparisons, the impact of rainfall variability on both functional and species-level biodiversity has received less attention. However, it is likely that shifts in the seasonality, and distribution of rainfall (i.e. changes in daily storm frequency and/or storm intensity) could substantially alter waterbalance of dryland ecosystems. In particular, the distribution of plant water use and plant water stress (proxies for growth and survival, respectively) are highly dependent on the temporal signatures of rainfall events within and between growing seasons. Therefore, ecosystem resilience is likely to be dependent on the functional - and species-level - responses of ecosystems to shifts in rainfall timing and intensity. This presentation will explore the potential and observed impacts of both seasonal and inter-annual variability in rainfall distribution in two classic dryland ecosystems. The first is the Kalahari region of southern Africa, where seasonal variability in rainfall patterns leads to functional organization of trees and grasses across a large climate gradient that optimize water use and minimize water stress. The second example is drawn from an east African savanna in Kenya, where observed shifts in rainfall seasonality are used to infer changes in the spatial distributions in the dominant woody species. Finally, I will address the critical need for new observational frameworks capable of directly measuring plant and ecosystem-scale responses to rainfall heterogeneity and propose a sampling design capable of resolving the functional response of vegetation to rainfall heterogeneity in water-limited landscapes.

  4. Features of the Functioning Bacterial Ecosystems in the Antarctic

    NASA Astrophysics Data System (ADS)

    Yakushev, A. V.; Churilin, N.; Soina, V. S.; Vorobyova, E. A.; Mergelov, N. S.

    2014-10-01

    Studies of bacterial communities in the samples of Antarctic soils by different methods showed that, both in liquid soil suspensions and in situ, microbial complexes are functioning presumably by forming biofilms -- the phenomenon that is more expressed in such habitat than in soils of temperate zones. Functional (trophic) diversity and physiological state of hydrolytic bacteria was studied in the samples at the upper layer (0-2 cm) of gravel pavement with algae, in the underlying peat horizon (2-4 cm) with inclusions of dead biomass and its underlying mineral horizon (4-10 cm) with signs of fungal mycelium. The investigated samples of Antarctic soils revealed different trophic diversity and the maximum specific growth rate on mineral medium with different biopolymers as the sole carbon source (starch, chitin, pectin, xylan, dextran-500, tween-20, casein); this can testify to differences in the physiological state of hydrolytic bacteria in various soil horizons and their readiness for growth. The most remarkable characteristics of the studied Antarctic soil as compared to the soils of temperate zone, was the unusual ability of hydrolytic community to consume chitin in the mineral horizon; this can be explained by the presence of fungal mycelium. Also, an almost complete lack in consumption of tween-20 (a water-soluble analogue of fat) by bacterial community of Arctic soil horizons are not explained and needs further verification. The higher functional diversity was detected in the upper horizon of the gravel pavement, which "protects" microorganisms from exposure to extreme temperatures, UV radiation, and desiccation, but the maximum specific growth rate was higher in the lower mineral horizon; this can be explained by the specificity of bacterial colonizing processes and unique formation of Antarctic soil microprofiles in the Larsemann oasis. The obtained data indicate a specific environmental strategy in the samples of Antarctic soils: development in lower

  5. Ecosystem function and services provided by the deep sea

    NASA Astrophysics Data System (ADS)

    Thurber, A. R.; Sweetman, A. K.; Narayanaswamy, B. E.; Jones, D. O. B.; Ingels, J.; Hansman, R. L.

    2013-11-01

    The deep sea is often viewed as a vast, dark, remote, and inhospitable environment, yet the deep ocean and seafloor are crucial to our lives through the services and provisions that they provide. Our understanding of how the deep sea functions remains limited, but when treated synoptically, a diversity of provisioning, regulating and cultural services become apparent. The biological pump transports carbon from the atmosphere into deep-ocean water masses which are separated over prolonged periods, reducing the impact of anthropogenic carbon release. Microbial oxidation of methane keeps another potent greenhouse gas out of the atmosphere while trapping carbon in authigenic carbonates. Nutrient regeneration by all faunal size classes provides the elements necessary to fuel surface productivity and fisheries, and microbial processes detoxify a diversity of compounds. Each of these processes occur on a very small scale, yet considering the vast area over which they occur they become important for the global functioning of the ocean. The deep sea also provides a diversity of resources, including fish stocks, enormous bioprospecting potential, and elements and energy reserves that are currently being extracted and will be increasingly important in the near future. Society benefits from the intrigue and mystery, the strange life forms, and the great unknown which has acted as a muse for inspiration and imagination since near the beginning of civilization. While many functions occur on the scale of microns to meters and time scales up to years, the derived services that result are only useful after centuries of integrated activity. This vast dark habitat, that covers the majority of the globe, harbors processes that directly impact humans in a diversity of ways, however the same traits that differentiate it from terrestrial or shallow marine systems also result in a greater need for integrated spatial and temporal understanding as it experiences increased use by society.

  6. Ecosystem function and services provided by the deep sea

    NASA Astrophysics Data System (ADS)

    Thurber, A. R.; Sweetman, A. K.; Narayanaswamy, B. E.; Jones, D. O. B.; Ingels, J.; Hansman, R. L.

    2014-07-01

    The deep sea is often viewed as a vast, dark, remote, and inhospitable environment, yet the deep ocean and seafloor are crucial to our lives through the services that they provide. Our understanding of how the deep sea functions remains limited, but when treated synoptically, a diversity of supporting, provisioning, regulating and cultural services becomes apparent. The biological pump transports carbon from the atmosphere into deep-ocean water masses that are separated over prolonged periods, reducing the impact of anthropogenic carbon release. Microbial oxidation of methane keeps another potent greenhouse gas out of the atmosphere while trapping carbon in authigenic carbonates. Nutrient regeneration by all faunal size classes provides the elements necessary for fueling surface productivity and fisheries, and microbial processes detoxify a diversity of compounds. Each of these processes occur on a very small scale, yet considering the vast area over which they occur they become important for the global functioning of the ocean. The deep sea also provides a wealth of resources, including fish stocks, enormous bioprospecting potential, and elements and energy reserves that are currently being extracted and will be increasingly important in the near future. Society benefits from the intrigue and mystery, the strange life forms, and the great unknown that has acted as a muse for inspiration and imagination since near the beginning of civilization. While many functions occur on the scale of microns to meters and timescales up to years, the derived services that result are only useful after centuries of integrated activity. This vast dark habitat, which covers the majority of the globe, harbors processes that directly impact humans in a variety of ways; however, the same traits that differentiate it from terrestrial or shallow marine systems also result in a greater need for integrated spatial and temporal understanding as it experiences increased use by society. In

  7. Abrupt shifts in ecosystem function and intensification of global biogeochemical cycle driven by hydroclimatic extremes

    NASA Astrophysics Data System (ADS)

    Ma, Xuanlong; Huete, Alfredo; Ponce-Campos, Guillermo; Zhang, Yongguang; Xie, Zunyi; Giovannini, Leandro; Cleverly, James; Eamus, Derek

    2016-04-01

    Amplification of the hydrologic cycle as a consequence of global warming is increasing the frequency, intensity, and spatial extent of extreme climate events globally. The potential influences resulting from amplification of the hydro-climatic cycle, coupled with an accelerating warming trend, pose great concerns on the sustainability of terrestrial ecosystems to sequester carbon, maintain biodiversity, provide ecosystem services, food security, and support human livelihood. Despite the great implications, the magnitude, direction, and carry-over effect of these extreme climate events on ecosystem function, remain largely uncertain. To address these pressing issues, we conducted an observational, interdisciplinary study using satellite retrievals of atmospheric CO2 and photosynthesis (chlorophyll fluorescence), and in-situ flux tower measures of ecosystem-atmosphere carbon exchange, to reveal the shifts in ecosystem function across extreme drought and wet periods. We further determine the factors that govern ecosystem sensitivity to hydroclimatic extremes. We focus on Australia but extended our analyses to other global dryland regions due to their significant role in global biogeochemical cycles. Our results revealed dramatic impacts of drought and wet hydroclimatic extremes on ecosystem function, with abrupt changes in vegetation productivity, carbon uptake, and water-use-efficiency between years. Drought resulted in widespread reductions or collapse in the normal patterns of vegetation growth seasonality such that in many cases there was no detectable phenological cycle during extreme drought years. We further identified a significant increasing trend (p < 0.001) in extreme wet year precipitation amounts over Australia and many other global regions, resulting in an increasing trend in magnitude of the episodic carbon sink pulses coupled to each La Niña-induced wet years. This finding is of global biogeochemical significance, with the consequence of amplifying

  8. Affect integration and reflective function: clarification of central conceptual issues.

    PubMed

    Solbakken, Ole André; Hansen, Roger Sandvik; Monsen, Jon Trygve

    2011-07-01

    The importance of affect regulation, modulation or integration for higher-order reflection and adequate functioning is increasingly emphasized across different therapeutic approaches and theories of change. These processes are probably central to any psychotherapeutic endeavor, whether explicitly conceptualized or not, and in recent years a number of therapeutic approaches have been developed that explicitly target them as a primary area of change. However, there still is important lack of clarity in the field regarding the understanding and operationalization of affect integration, particularly when it comes to specifying underlying mechanisms, the significance of different affect states, and the establishment of operational criteria for measurement. The conceptual relationship between affect integration and reflective function thus remains ambiguous. The present article addresses these topics, indicating ways in which a more complex and exhaustive understanding of integration of affect, cognition and behavior can be attained.

  9. Arctic ecosystem functional zones: identification and quantification using an above and below ground monitoring strategy

    NASA Astrophysics Data System (ADS)

    Hubbard, Susan S.; Ajo-Franklin, Jonathan B.; Dafflon, Baptiste; Dou, Shan; Kneafsey, Tim J.; Peterson, John E.; Tas, Neslihan; Torn, Margaret S.; Phuong Tran, Anh; Ulrich, Craig; Wainwright, Haruko; Wu, Yuxin; Wullschleger, Stan

    2015-04-01

    Although accurate prediction of ecosystem feedbacks to climate requires characterization of the properties that influence terrestrial carbon cycling, performing such characterization is challenging due to the disparity of scales involved. This is particularly true in vulnerable Arctic ecosystems, where microbial activities leading to the production of greenhouse gasses are a function of small-scale hydrological, geochemical, and thermal conditions influenced by geomorphology and seasonal dynamics. As part of the DOE Next-Generation Ecosystem Experiment (NGEE-Arctic), we are advancing two approaches to improve the characterization of complex Arctic ecosystems, with an initial application to an ice-wedge polygon dominated tundra site near Barrow, AK, USA. The first advance focuses on developing a new strategy to jointly monitor above- and below- ground properties critical for carbon cycling in the tundra. The strategy includes co-characterization of properties within the three critical ecosystem compartments: land surface (vegetation, water inundation, snow thickness, and geomorphology); active layer (peat thickness, soil moisture, soil texture, hydraulic conductivity, soil temperature, and geochemistry); and permafrost (mineral soil and ice content, nature, and distribution). Using a nested sampling strategy, a wide range of measurements have been collected at the study site over the past three years, including: above-ground imagery (LiDAR, visible, near infrared, NDVI) from various platforms, surface geophysical datasets (electrical, electromagnetic, ground penetrating radar, seismic), and point measurements (such as CO2 and methane fluxes, soil properties, microbial community composition). A subset of the coincident datasets is autonomously collected daily. Laboratory experiments and new inversion approaches are used to improve interpretation of the field geophysical datasets in terms of ecosystem properties. The new strategy has significantly advanced our ability

  10. How Does Maternal Employment Affect Children's Socioemotional Functioning?

    ERIC Educational Resources Information Center

    Lam, Gigi

    2015-01-01

    The maternal employment becomes an irreversible trend across the globe. The effect of maternal employment on children's socioemotional functioning is so pervasive that it warrants special attention to investigate into the issue. A trajectory of analytical framework of how maternal employment affects children's socioemotional functioning originates…

  11. Quantifying the importance of plant functional diversity for ecosystem functioning and resilience under scenarios of climate change (Invited)

    NASA Astrophysics Data System (ADS)

    Pavlick, R.; Drewry, D.; Kleidon, A.

    2013-12-01

    Dynamic Global Vegetation Models (DGVMs) typically employ only a small set of Plant Functional Types (PFTs) to represent the vast diversity of observed vegetation forms and functioning. There is growing evidence, however, that this abstraction may not adequately represent the observed variation in plant functional traits, which is thought to play an important role for many ecosystem functions and for ecosystem resilience to environmental change. The geographic distribution of PFTs in these models is also often based on empirical relationships between present-day climate and vegetation patterns. Projections of future climate change, however, point toward the possibility of novel regional climates, which could lead to no-analog vegetation compositions incompatible with the PFT paradigm. Here, we present results from the Jena Diversity-DGVM (JeDi-DGVM), a novel traits-based vegetation model, which simulates a large number of hypothetical plant growth strategies constrained by functional tradeoffs, thereby allowing for a more flexible temporal and spatial representation of the terrestrial biosphere. We run two sets of model experiments forced with the latest bias-corrected climate change scenarios from several different global climate models. In the first set, we simulate a diverse biosphere using a large number of plant growth strategies, allowing the modelled ecosystems to adapt through emergent changes in ecosystem composition. We then aggregate the surviving growth strategies from the first set of diverse simulations to a small number of biome-averaged growth strategies, recreating something akin to PFTs. We use this smaller set of PFT-like growth strategies to represent a sparse or low-diversity biosphere in the second set of model experiments. We quantify the importance of functional diversity by comparing key metrics of ecosystem functioning across the two sets of simulations. The results reveal the implications of using the common PFT vegetation modelling

  12. Changes of ecosystem functions in a Mediterranean shrubland exposed for eight years to prolonged summer droughts

    NASA Astrophysics Data System (ADS)

    de Dato, Giovanbattista; de Angelis, Paolo; Cesaraccio, Carla; Pellizzaro, Grazia; Duce, Pierpaolo; Sirca, Costantino; Spano, Donatella; Beier, Claus

    2010-05-01

    Where water is a limiting factor, like in arid and semiarid shrubland ecosystems of the Mediterranean basin, soil moisture, strengthen by high temperatures, is the key limiting factor controlling biogeochemical cycles. During the drought season, the unavailable water reduces plant growth, litter decomposition and microbial soil respiration. In order to assess the impacts of precipitation reduction on Mediterranean shrublands, a natural community has been exposed since 2001 to prolonged summer droughts by means of mobile plastic roofs, covering three experimental plots (20 m2) during rain events, in spring and in autumn. Three additional plots were used as control. The vegetation reaches a maximum height of 1.0 m and the main shrub species are Cistus monspeliensis, Helichrysum italicum and Dorycnium pentaphyllum. Bare soil constitutes about 20% of the plot surface. The aim of this paper is to summarize the impact of the treatment on the plant community structure and on ecosystem functions, after 8 years of experimentation. A general increase of vegetation cover was observed in the whole community during the years, as result of a natural process of recolonisation. This positive temporal pattern was mainly observed in the control plots, whereas in the drought treatment it was less evident and practically null in the year 2003. At species-specific level, a clear negative effect of drought treatment was observed for C. monspeliensis. Moreover, anticipated drought reduced C assimilation and induced an earlier change of leaf morphology in Cistus. These effects produced the reduction of LAI and of whole plant productivity. The seasonal pattern of soil CO2 efflux was characterized by higher rates during the wet vegetative season (autumn-spring) and lower rates during the dry non-vegetative season (summer). Significant negative effects were occasionally recorded during the period with the treatment turned on. The relation of soil respiration with temperature and soil water

  13. Direct and indirect effects of copper-contaminated sediments on the functions of model freshwater ecosystems.

    PubMed

    Gardham, Stephanie; Chariton, Anthony A; Hose, Grant C

    2015-01-01

    Copper is acutely toxic to, and directly affects, primary producers and decomposers, which are key players in essential processes such as the nutrient cycle in freshwater ecosystems. Even though the indirect effects of metals (for example effects due to changes in species interactions) may be more common than direct effects, little is known about the indirect effects of copper on primary producers and decomposers. The effects of copper on phytoplankton, macrophytes, periphyton and organic matter decomposition in an outdoor lentic mesocosm facility were assessed, and links between the responses examined. Copper directly decreased macrophyte growth, subsurface organic matter decomposition, and the potential for high phytoplankton Chlorophyll a concentrations. However, periphyton cover and organic matter decomposition on the surface of the sediment were stimulated by the presence of copper. These latter responses were attributed to indirect effects, due to a reduction in grazing pressure from snails, particularly Physa acuta, in the higher copper-contaminated mesocosms. This permitted the growth of periphyton and other heterotrophs, ultimately increasing decomposition at the sediment surface. The present study demonstrates the pronounced influence indirect effects may have on ecological function, findings that may not be observed in traditional laboratory studies (which utilize single species or simplistic communities).

  14. Virus decomposition provides an important contribution to benthic deep-sea ecosystem functioning.

    PubMed

    Dell'Anno, Antonio; Corinaldesi, Cinzia; Danovaro, Roberto

    2015-04-21

    Viruses are key biological agents of prokaryotic mortality in the world oceans, particularly in deep-sea ecosystems where nearly all of the prokaryotic C production is transformed into organic detritus. However, the extent to which the decomposition of viral particles (i.e., organic material of viral origin) influences the functioning of benthic deep-sea ecosystems remains completely unknown. Here, using various independent approaches, we show that in deep-sea sediments an important fraction of viruses, once they are released by cell lysis, undergo fast decomposition. Virus decomposition rates in deep-sea sediments are high even at abyssal depths and are controlled primarily by the extracellular enzymatic activities that hydrolyze the proteins of the viral capsids. We estimate that on a global scale the decomposition of benthic viruses releases ∼37-50 megatons of C per year and thus represents an important source of labile organic compounds in deep-sea ecosystems. Organic material released from decomposed viruses is equivalent to 3 ± 1%, 6 ± 2%, and 12 ± 3% of the input of photosynthetically produced C, N, and P supplied through particles sinking to bathyal/abyssal sediments. Our data indicate that the decomposition of viruses provides an important, previously ignored contribution to deep-sea ecosystem functioning and has an important role in nutrient cycling within the largest ecosystem of the biosphere.

  15. Virus decomposition provides an important contribution to benthic deep-sea ecosystem functioning

    PubMed Central

    Dell’Anno, Antonio; Corinaldesi, Cinzia

    2015-01-01

    Viruses are key biological agents of prokaryotic mortality in the world oceans, particularly in deep-sea ecosystems where nearly all of the prokaryotic C production is transformed into organic detritus. However, the extent to which the decomposition of viral particles (i.e., organic material of viral origin) influences the functioning of benthic deep-sea ecosystems remains completely unknown. Here, using various independent approaches, we show that in deep-sea sediments an important fraction of viruses, once they are released by cell lysis, undergo fast decomposition. Virus decomposition rates in deep-sea sediments are high even at abyssal depths and are controlled primarily by the extracellular enzymatic activities that hydrolyze the proteins of the viral capsids. We estimate that on a global scale the decomposition of benthic viruses releases ∼37–50 megatons of C per year and thus represents an important source of labile organic compounds in deep-sea ecosystems. Organic material released from decomposed viruses is equivalent to 3 ± 1%, 6 ± 2%, and 12 ± 3% of the input of photosynthetically produced C, N, and P supplied through particles sinking to bathyal/abyssal sediments. Our data indicate that the decomposition of viruses provides an important, previously ignored contribution to deep-sea ecosystem functioning and has an important role in nutrient cycling within the largest ecosystem of the biosphere. PMID:25848024

  16. Using experimental manipulation to assess the roles of leaf litter in the functioning of forest ecosystems.

    PubMed

    Sayer, Emma J

    2006-02-01

    The widespread use of forest litter as animal bedding in central Europe for many centuries gave rise to the first litter manipulation studies, and their results demonstrated that litter and its decomposition are a vital part of ecosystem function. Litter plays two major roles in forest ecosystems: firstly, litterfall is an inherent part of nutrient and carbon cycling, and secondly, litter forms a protective layer on the soil surface that also regulates microclimatic conditions. By reviewing 152 years of litter manipulation experiments, I show that the effects of manipulating litter stem from changes in one, or both, of these two functions, and interactions between the variables influenced by the accumulation of litter can result in feedback mechanisms that may intensify treatment effects or mask responses, making the interpretation of results difficult.Long-term litter removal increased soil bulk density, overland flow, erosion, and temperature fluctuations and upset the soil water balance, causing lower soil water content during dry periods. Soil pH increased or decreased in response to manipulation treatments depending on forest type and initial soil pH, but it is unclear why there was no uniform response. Long-term litter harvesting severely depleted the forests of nutrients. Decreases in the concentrations of available P, Ca, Mg, and K in the soil occurred after only three to five years. The decline in soil N occurred over longer periods of time, and the relative loss was greater in soils with high initial nitrogen concentration. Tree growth declined with long-term litter removal, probably due to lower nutrient availability. Litter manipulation also added or removed large amounts of carbon thereby affecting microbial communities and altering soil respiration rates. Litter manipulation experiments have shown that litter cover acts as a physical barrier to the shoot emergence of small-seeded species; further, the microclimate maintained by the litter layer may be

  17. Fine sediment as environmental stressor affecting freshwater mussel behavior and ecosystem services.

    PubMed

    Lummer, Eva-Maria; Auerswald, Karl; Geist, Juergen

    2016-11-15

    Fine sediment pollution is considered a major stressor for aquatic ecosystems and their biodiversity. In particular, fine sediments have been suggested to play a crucial role in the declines of freshwater mussels which are considered keystone fauna of streams and rivers. Whereas the effects of deposited fine sediments on recruitment failure are well known, effects of suspended fine sediments on adult mussel behavior are less studied. Therefore the aim of this study was to investigate the effects of fine sediment exposure on freshwater mussel behavior and on mussel-dependent ecosystem services. Unio pictorum mussels were used to test three behavioral endpoints: Hall activity, transition frequency and relative water clearance rate. Mussels were exposed to fine sediments of different particle size classes (<45μm, 45-63μm, 63-125μm) and different concentration (0-10gL(-1)) of the smallest particle size class. Hall sensor technology and turbidity measurements were used to detect mussel behavior in presence of suspended sediments. Results revealed that mussels improve clearance of suspended particles out of the water column by 35%, independent of particle size class and concentration. Transition frequency was determined an unsuitable behavioral endpoint for non-soluble substances. Contrary to previous studies, we could demonstrate that fine sediments do not interfere with filtration by mussels and that mussels have a great influence on water purification, providing a valuable ecosystem service. PMID:27422724

  18. Biodiversity and Ecosystem Functioning: Exploring Principles of Ecology with Agricultural Plants

    ERIC Educational Resources Information Center

    Ruesink, Jennifer; O'Connor, Eileen; Sparks, Grace

    2006-01-01

    To date, little of the ecological research on biological diversity and ecosystem functioning has been carried out in agricultural systems, despite the fact that agriculture is a major contributor to loss of native habitats and species. However, agricultural research has demonstrated that polycultures of multiple crop species can have higher total…

  19. Extreme drought event and shrub invasion combine to reduce ecosystem functioning and resilience in water-limited climates

    NASA Astrophysics Data System (ADS)

    Caldeira, Maria; Lecomte, Xavier; David, Teresa; Pinto, Joaquim; Bugalho, Miguel; Werner, Christiane

    2016-04-01

    Extreme droughts and plant invasions are major drivers of global change that can critically affect ecosystem functioning. Shrub encroachment is increasing in many regions worldwide and extreme events are projected to increase in frequency and intensity, namely in the Mediterranean region. Nevertheless, little is known about how these drivers may interact and affect ecosystem functioning and resilience to extreme droughts. Using a manipulative shrub removal experiment and the co-occurrence of an extreme drought event (2011/2012) in a Mediterranean woodland, we show that the native shrub invasion and extreme drought combined to reduce ecosystem transpiration and the resilience of the key-stone oak tree species. We established six 25 x 25 m paired plots in a shrub (Cistus ladanifer L.) encroached Mediterranean cork-oak (Quercus suber L.) woodland. We measured sapflow and pre-dawn leaf water potential of trees and shrubs and soil water content in all plots during three years. We determined the resilience of tree transpiration to evaluate to what extent trees recovered from the extreme drought event. From February to November 2011 we conducted baseline measurements for plot comparison. In November 2011 all the shrubs from one of all the paired plots were cut and removed. Ecosystem transpiration was dominated by the water use of the invasive shrub, which further increased after the extreme drought. Simultaneously, tree transpiration in invaded plots declined much stronger (67 ± 13 %) than in plots cleared from shrubs (31 ± 11%) relative to the pre-drought year. Trees in invaded plots were not able to recover in the following wetter year showing lower resilience to the extreme drought event. Our results imply that in Mediterranean-type of climates invasion by water spending species can combine with projected recurrent extreme droughts causing critical drought tolerance thresholds of trees to be overcome increasing the probability of tree mortality (Caldeira et.al. 2015

  20. Implications for Ecosystem Services of Watershed Processes that affect the Transport and Transformations of Mercury in an Adirondack Stream Basin

    NASA Astrophysics Data System (ADS)

    Burns, D. A.; Riva-Murray, K.; Bradley, P. M.

    2012-12-01

    Mercury (Hg) is a potent neurotoxin that can affect the health of humans and wildlife through the ingestion of methyl Hg. Mercury contamination of ecosystems originates from human activities such as mining, coal burning and other industrial emissions, and the use of Hg-containing products. Natural sources such as volcanic and geothermal emissions and the weathering of Hg-bearing minerals also contribute to Hg contamination, but are believed to be minor sources in most ecosystems. Various ecosystem disturbances including fires, forest harvesting, and the submergence of land by impoundment may also contribute to Hg ecosystem contamination by mobilizing stores that have previously originated from the sources described above. Mercury from a mix of regional and global emissions sources is transported in the atmosphere to remote landscapes that are distant from local emissions sources. The Adirondacks of New York State is a forested, mountainous region characterized by abundant lakes and streams, and is distant from local emissions sources. Recreational fishing, wildlife viewing, hiking, and hunting are valued ecosystem services in this region. Here, we report on the relevance to ecosystem services of findings based on five years of Hg data collection of stream water, groundwater, invertebrates, and fish in the upper Hudson River basin in the central part of the Adirondack region. The New York State Dept. of Health has issued fish consumption advisories for the entire Adirondacks based on elevated levels previously measured in lakes and rivers of this region. Our work seeks improved understanding and models of the landscape sources and watershed processes that control the transformation of Hg to its methyl form (MeHg), the transport of MeHg to streams, and bioaccumulation of MeHg in aquatic food webs. Mean annual atmospheric Hg deposition was 6.3 μg/m2/yr during 2007-09, compared to mean annual filtered total Hg stream yields of 1.66 μg/m2/yr and filtered MeHg stream

  1. Biogeochemical significance of pelagic ecosystem function: an end-Cretaceous case study.

    PubMed

    Henehan, Michael J; Hull, Pincelli M; Penman, Donald E; Rae, James W B; Schmidt, Daniela N

    2016-05-19

    Pelagic ecosystem function is integral to global biogeochemical cycling, and plays a major role in modulating atmospheric CO2 concentrations (pCO2). Uncertainty as to the effects of human activities on marine ecosystem function hinders projection of future atmospheric pCO2 To this end, events in the geological past can provide informative case studies in the response of ecosystem function to environmental and ecological changes. Around the Cretaceous-Palaeogene (K-Pg) boundary, two such events occurred: Deccan large igneous province (LIP) eruptions and massive bolide impact at the Yucatan Peninsula. Both perturbed the environment, but only the impact coincided with marine mass extinction. As such, we use these events to directly contrast the response of marine biogeochemical cycling to environmental perturbation with and without changes in global species richness. We measure this biogeochemical response using records of deep-sea carbonate preservation. We find that Late Cretaceous Deccan volcanism prompted transient deep-sea carbonate dissolution of a larger magnitude and timescale than predicted by geochemical models. Even so, the effect of volcanism on carbonate preservation was slight compared with bolide impact. Empirical records and geochemical models support a pronounced increase in carbonate saturation state for more than 500 000 years following the mass extinction of pelagic carbonate producers at the K-Pg boundary. These examples highlight the importance of pelagic ecosystems in moderating climate and ocean chemistry. PMID:27114586

  2. Biogeochemical significance of pelagic ecosystem function: an end-Cretaceous case study.

    PubMed

    Henehan, Michael J; Hull, Pincelli M; Penman, Donald E; Rae, James W B; Schmidt, Daniela N

    2016-05-19

    Pelagic ecosystem function is integral to global biogeochemical cycling, and plays a major role in modulating atmospheric CO2 concentrations (pCO2). Uncertainty as to the effects of human activities on marine ecosystem function hinders projection of future atmospheric pCO2 To this end, events in the geological past can provide informative case studies in the response of ecosystem function to environmental and ecological changes. Around the Cretaceous-Palaeogene (K-Pg) boundary, two such events occurred: Deccan large igneous province (LIP) eruptions and massive bolide impact at the Yucatan Peninsula. Both perturbed the environment, but only the impact coincided with marine mass extinction. As such, we use these events to directly contrast the response of marine biogeochemical cycling to environmental perturbation with and without changes in global species richness. We measure this biogeochemical response using records of deep-sea carbonate preservation. We find that Late Cretaceous Deccan volcanism prompted transient deep-sea carbonate dissolution of a larger magnitude and timescale than predicted by geochemical models. Even so, the effect of volcanism on carbonate preservation was slight compared with bolide impact. Empirical records and geochemical models support a pronounced increase in carbonate saturation state for more than 500 000 years following the mass extinction of pelagic carbonate producers at the K-Pg boundary. These examples highlight the importance of pelagic ecosystems in moderating climate and ocean chemistry.

  3. Tree species and functional traits but not species richness affect interrill erosion processes in young subtropical forests

    NASA Astrophysics Data System (ADS)

    Seitz, S.; Goebes, P.; Song, Z.; Bruelheide, H.; Härdtle, W.; Kühn, P.; Li, Y.; Scholten, T.

    2016-01-01

    Soil erosion is seriously threatening ecosystem functioning in many parts of the world. In this context, it is assumed that tree species richness and functional diversity of tree communities can play a critical role in improving ecosystem services such as erosion control. An experiment with 170 micro-scale run-off plots was conducted to investigate the influence of tree species and tree species richness as well as functional traits on interrill erosion in a young forest ecosystem. An interrill erosion rate of 47.5 Mg ha-1 a-1 was calculated. This study provided evidence that different tree species affect interrill erosion differently, while tree species richness did not affect interrill erosion in young forest stands. Thus, different tree morphologies have to be considered, when assessing soil erosion under forest. High crown cover and leaf area index reduced interrill erosion in initial forest ecosystems, whereas rising tree height increased it. Even if a leaf litter cover was not present, the remaining soil surface cover by stones and biological soil crusts was the most important driver for soil erosion control. Furthermore, soil organic matter had a decreasing influence on interrill erosion. Long-term monitoring of soil erosion under closing tree canopies is necessary, and a wide range of functional tree traits should be considered in future research.

  4. Integrating Organic Matter Structure with Ecosystem Function using Advanced Analytical Chemistry Techniques

    NASA Astrophysics Data System (ADS)

    Boot, C. M.

    2012-12-01

    Microorganisms are the primary transformers of organic matter in terrestrial and aquatic ecosystems. The structure of organic matter controls its bioavailability and researchers have long sought to link the chemical characteristics of the organic matter pool to its lability. To date this effort has been primarily attempted using low resolution descriptive characteristics (e.g. organic matter content, carbon to nitrogen ratio, aromaticity, etc .). However, recent progress in linking these two important ecosystem components has been advanced using advanced high resolution tools (e.g. nuclear magnetic resonance (NMR) spectroscopy, and mass spectroscopy (MS)-based techniques). A series of experiments will be presented that highlight the application of high resolution techniques in a variety of terrestrial and aquatic ecosystems with the focus on how these data explicitly provide the foundation for integrating organic matter structure into our concept of ecosystem function. The talk will highlight results from a series of experiments including: an MS-based metabolomics and fluorescence excitation emission matrix approach evaluating seasonal and vegetation based changes in dissolved organic matter (DOM) composition from arctic soils; Fourier transform ion cyclotron resonance (FTICR) MS and MS metabolomics analysis of DOM from three lakes in an alpine watershed; and the transformation of 13C labeled glucose track with NMR during a rewetting experiment from Colorado grassland soils. These data will be synthesized to illustrate how the application of advanced analytical techniques provides novel insight into our understanding of organic matter processing in a wide range of ecosystems.

  5. Exploring the Red Sea seasonal ecosystem functioning using a three-dimensional biophysical model

    NASA Astrophysics Data System (ADS)

    Triantafyllou, G.; Yao, F.; Petihakis, G.; Tsiaras, K. P.; Raitsos, D. E.; Hoteit, I.

    2014-03-01

    The Red Sea exhibits complex hydrodynamic and biogeochemical dynamics, which vary both in time and space. These dynamics have been explored through the development and application of a 3-D ecosystem model. The simulation system comprises two off-line coupled submodels: the MIT General Circulation Model (MITgcm) and the European Regional Seas Ecosystem Model (ERSEM), both adapted for the Red Sea. The results from an annual simulation under climatological forcing are presented. Simulation results are in good agreement with satellite and in situ data illustrating the role of the physical processes in determining the evolution and variability of the Red Sea ecosystem. The model was able to reproduce the main features of the Red Sea ecosystem functioning, including the exchange with the Gulf of Aden, which is a major driving mechanism for the whole Red Sea ecosystem and the winter overturning taking place in the north. Some model limitations, mainly related to the dynamics of the extended reef system located in the southern part of the Red Sea, which is not currently represented in the model, still need to be addressed.

  6. Functional diversity of marine ecosystems after the Late Permian mass extinction event

    NASA Astrophysics Data System (ADS)

    Foster, William J.; Twitchett, Richard J.

    2014-03-01

    The Late Permian mass extinction event about 252 million years ago was the most severe biotic crisis of the past 500 million years and occurred during an episode of global warming. The loss of around two-thirds of marine genera is thought to have had substantial ecological effects, but the overall impacts on the functioning of marine ecosystems and the pattern of marine recovery are uncertain. Here we analyse the fossil occurrences of all known benthic marine invertebrate genera from the Permian and Triassic periods, and assign each to a functional group based on their inferred lifestyle. We show that despite the selective extinction of 62-74% of these genera, all but one functional group persisted through the crisis, indicating that there was no significant loss of functional diversity at the global scale. In addition, only one new mode of life originated in the extinction aftermath. We suggest that Early Triassic marine ecosystems were not as ecologically depauperate as widely assumed. Functional diversity was, however, reduced in particular regions and habitats, such as tropical reefs; at these smaller scales, recovery varied spatially and temporally, probably driven by migration of surviving groups. We find that marine ecosystems did not return to their pre-extinction state, and by the Middle Triassic greater functional evenness is recorded, resulting from the radiation of previously subordinate groups such as motile, epifaunal grazers.

  7. Scaling up functional traits for ecosystem services with remote sensing: concepts and methods.

    PubMed

    Abelleira Martínez, Oscar J; Fremier, Alexander K; Günter, Sven; Ramos Bendaña, Zayra; Vierling, Lee; Galbraith, Sara M; Bosque-Pérez, Nilsa A; Ordoñez, Jenny C

    2016-07-01

    Ecosystem service-based management requires an accurate understanding of how human modification influences ecosystem processes and these relationships are most accurate when based on functional traits. Although trait variation is typically sampled at local scales, remote sensing methods can facilitate scaling up trait variation to regional scales needed for ecosystem service management. We review concepts and methods for scaling up plant and animal functional traits from local to regional spatial scales with the goal of assessing impacts of human modification on ecosystem processes and services. We focus our objectives on considerations and approaches for (1) conducting local plot-level sampling of trait variation and (2) scaling up trait variation to regional spatial scales using remotely sensed data. We show that sampling methods for scaling up traits need to account for the modification of trait variation due to land cover change and species introductions. Sampling intraspecific variation, stratification by land cover type or landscape context, or inference of traits from published sources may be necessary depending on the traits of interest. Passive and active remote sensing are useful for mapping plant phenological, chemical, and structural traits. Combining these methods can significantly improve their capacity for mapping plant trait variation. These methods can also be used to map landscape and vegetation structure in order to infer animal trait variation. Due to high context dependency, relationships between trait variation and remotely sensed data are not directly transferable across regions. We end our review with a brief synthesis of issues to consider and outlook for the development of these approaches. Research that relates typical functional trait metrics, such as the community-weighted mean, with remote sensing data and that relates variation in traits that cannot be remotely sensed to other proxies is needed. Our review narrows the gap between

  8. Scaling up functional traits for ecosystem services with remote sensing: concepts and methods.

    PubMed

    Abelleira Martínez, Oscar J; Fremier, Alexander K; Günter, Sven; Ramos Bendaña, Zayra; Vierling, Lee; Galbraith, Sara M; Bosque-Pérez, Nilsa A; Ordoñez, Jenny C

    2016-07-01

    Ecosystem service-based management requires an accurate understanding of how human modification influences ecosystem processes and these relationships are most accurate when based on functional traits. Although trait variation is typically sampled at local scales, remote sensing methods can facilitate scaling up trait variation to regional scales needed for ecosystem service management. We review concepts and methods for scaling up plant and animal functional traits from local to regional spatial scales with the goal of assessing impacts of human modification on ecosystem processes and services. We focus our objectives on considerations and approaches for (1) conducting local plot-level sampling of trait variation and (2) scaling up trait variation to regional spatial scales using remotely sensed data. We show that sampling methods for scaling up traits need to account for the modification of trait variation due to land cover change and species introductions. Sampling intraspecific variation, stratification by land cover type or landscape context, or inference of traits from published sources may be necessary depending on the traits of interest. Passive and active remote sensing are useful for mapping plant phenological, chemical, and structural traits. Combining these methods can significantly improve their capacity for mapping plant trait variation. These methods can also be used to map landscape and vegetation structure in order to infer animal trait variation. Due to high context dependency, relationships between trait variation and remotely sensed data are not directly transferable across regions. We end our review with a brief synthesis of issues to consider and outlook for the development of these approaches. Research that relates typical functional trait metrics, such as the community-weighted mean, with remote sensing data and that relates variation in traits that cannot be remotely sensed to other proxies is needed. Our review narrows the gap between

  9. Is the Climate of Bering Sea Warming and Affecting the Ecosystem?

    NASA Astrophysics Data System (ADS)

    Overland, James E.; Stabeno, Phyllis J.

    2004-08-01

    Observations from the Bering Sea are good indicators of decadal shifts in climate, as the Bering is a transition region between the cold, dry Arctic air mass to the north, and the moist, relatively warm maritime air mass to the south. The Bering Sea is also a transition region between Arctic and sub-Arctic ecosystems; this boundary can be loosely identified with the extent of winter sea-ice cover. Like a similar transition zone in the eastern North Atlantic, the Bering Sea is experiencing a northward biogeographical shift in response to changing temperature and atmospheric forcing. If this shift continues over the next decade, it will have major impacts on commercial and subsistence harvests as Arctic species are displaced by sub-Arctic species. The stakes are enormous, as this rich and diverse ecosystem currently provides 47% of the U.S. fishery production by weight, and is home to 80% of the U.S. sea bird population, 95% of northern fur seals, and major populations of Steller sea lions, walrus, and whales.

  10. [Ecological function evaluation and related management strategies of river ecosystem in Taizi River basin, North China].

    PubMed

    Liu, Hong-Yan; Zhang, Yuan; Ma, Shu-Qin; Meng, Wei

    2013-10-01

    By the method of index evaluation at reach scale, this paper evaluated the ecological functions of aquatic biodiversity maintenance, habitat maintenance, water quality sustainment, and hydrological support of the river system in Taizi River basin of North China. The dominant ecological functions and the total ecological function were determined after sorting and summing. All the reaches in the basin were divided into four hierarchies of ecological functions. Overall, the total ecological function showed a spatially degrading trend from the mountainous region to the plain. Based on the evaluation results of the total function and dominant functions, six ecosystem management strategies were proposed. For the reaches with the functions of aquatic biodiversity- and habitat maintenance, the primary ecological management strategies included ecological conservation, ecological maintenance, and ecological restoration; for the reaches with the functions of water quality sustainment and hydrological support, the primary strategies of ecological management included limited development, development optimization, and exploitation.

  11. Anthropogenic impacts on tropical forest biodiversity: a network structure and ecosystem functioning perspective

    PubMed Central

    Morris, Rebecca J.

    2010-01-01

    Huge areas of diverse tropical forest are lost or degraded every year with dramatic consequences for biodiversity. Deforestation and fragmentation, over-exploitation, invasive species and climate change are the main drivers of tropical forest biodiversity loss. Most studies investigating these threats have focused on changes in species richness or species diversity. However, if we are to understand the absolute and long-term effects of anthropogenic impacts on tropical forests, we should also consider the interactions between species, how those species are organized in networks, and the function that those species perform. I discuss our current knowledge of network structure and ecosystem functioning, highlighting empirical examples of their response to anthropogenic impacts. I consider the future prospects for tropical forest biodiversity, focusing on biodiversity and ecosystem functioning in secondary forest. Finally, I propose directions for future research to help us better understand the effects of anthropogenic impacts on tropical forest biodiversity. PMID:20980318

  12. Combined impacts of global warming and pollution: impacts on food web structure and ecosystem function.

    NASA Astrophysics Data System (ADS)

    Thompson, R. M.

    2005-05-01

    Effects of global species loss on ecosystem function have traditionally been extrapolated from studies which investigate the effect of random species loss or addition. Real species loss is highly patterned and clumped according to trophic position, taxonomic relatedness and interconnectedness with the remainder of the food web. Using pond microcosms, I evoked a realistic pattern of species loss using toxins and warming. Species loss was predictably highly patterned. Influences on ecosystem functions ranged from simple and linear in the case of algal productivity, through to complex and step-like in the case of bacterial decomposition. Impacts on algal productivity were mediated by effects on the rate of grazing by invertebrates. There is strong evidence from the bacterial decomposition results of an `insurance effect' whereby the presence of multiple stressors has a strong, non-additive effect on function. These results clearly show that the traditional ecotoxicological practice of studying effects of single toxins on single species may be highly misleading.

  13. Light availability affects stream biofilm bacterial community composition and function, but not diversity.

    PubMed

    Wagner, Karoline; Besemer, Katharina; Burns, Nancy R; Battin, Tom J; Bengtsson, Mia M

    2015-12-01

    Changes in riparian vegetation or water turbidity and browning in streams alter the local light regime with potential implications for stream biofilms and ecosystem functioning. We experimented with biofilms in microcosms grown under a gradient of light intensities (range: 5-152 μmole photons s(-1)  m(-2) ) and combined 454-pyrosequencing and enzymatic activity assays to evaluate the effects of light on biofilm structure and function. We observed a shift in bacterial community composition along the light gradient, whereas there was no apparent change in alpha diversity. Multifunctionality, based on extracellular enzymes, was highest under high light conditions and decoupled from bacterial diversity. Phenol oxidase activity, involved in the degradation of polyphenolic compounds, was twice as high on average under the lowest compared with the highest light condition. This suggests a shift in reliance of microbial heterotrophs on biofilm phototroph-derived organic matter under high light availability to more complex organic matter under low light. Furthermore, extracellular enzyme activities correlated with nutrient cycling and community respiration, supporting the link between biofilm structure-function and biogeochemical fluxes in streams. Our findings demonstrate that changes in light availability are likely to have significant impacts on biofilm structure and function, potentially affecting stream ecosystem processes.

  14. Light availability affects stream biofilm bacterial community composition and function, but not diversity.

    PubMed

    Wagner, Karoline; Besemer, Katharina; Burns, Nancy R; Battin, Tom J; Bengtsson, Mia M

    2015-12-01

    Changes in riparian vegetation or water turbidity and browning in streams alter the local light regime with potential implications for stream biofilms and ecosystem functioning. We experimented with biofilms in microcosms grown under a gradient of light intensities (range: 5-152 μmole photons s(-1)  m(-2) ) and combined 454-pyrosequencing and enzymatic activity assays to evaluate the effects of light on biofilm structure and function. We observed a shift in bacterial community composition along the light gradient, whereas there was no apparent change in alpha diversity. Multifunctionality, based on extracellular enzymes, was highest under high light conditions and decoupled from bacterial diversity. Phenol oxidase activity, involved in the degradation of polyphenolic compounds, was twice as high on average under the lowest compared with the highest light condition. This suggests a shift in reliance of microbial heterotrophs on biofilm phototroph-derived organic matter under high light availability to more complex organic matter under low light. Furthermore, extracellular enzyme activities correlated with nutrient cycling and community respiration, supporting the link between biofilm structure-function and biogeochemical fluxes in streams. Our findings demonstrate that changes in light availability are likely to have significant impacts on biofilm structure and function, potentially affecting stream ecosystem processes. PMID:26013911

  15. Impacts of extreme hydro-meteorological conditions on ecosystem functioning and productivity patterns across Australia

    NASA Astrophysics Data System (ADS)

    Huete, Alfredo; Ma, Xuanlong; Xie, Zunyi; Restrepo-Coupe, Natalia; Ponce-Campos, Guillermo

    2016-04-01

    As Earth's climate continues to change, the frequency and intensity of warm droughts, extreme precipitation patterns, and heat waves will alter in potentially different ways, ecosystem structure and functioning with major impacts on carbon and water balance, and food security. The extreme hydro-meteorological conditions that are presently impacting Australia approach those anticipated with future climate change and thus provide unique opportunities to study ecological sensitivity and functional responses and cross-biome productivity changes using contemporary, in-situ and satellite observational datasets. Here, we combined satellite vegetation index products from MODIS and AVHRR, total water storage (TWS) from the GRACE twin satellites, precipitation data and in-situ tower flux measurements to characterise ecosystem sensitivity, and analyse climate change impacts on ecosystem productivity and resilience. Recent advances in eddy covariance tower flux measurements and spatially contiguous remote sensing data provide innovative and promising capabilities to extend ecosystem functioning and productivity studies from local to regional and continental scales. In general, Australia exhibited ecosystem-level shifts in water demands with water availability across wet and dry years, and over all biomes analysed (arid grasslands to humid forests). In the drier years, higher ecosystem water use efficiencies (WUEe) enabled plants to maintain higher levels of productivity than would otherwise be expected for the lower amounts of rainfall and available water. Further, there were unique, functional class-specific coping strategies to drought and water availability. With prolonged warm drought conditions, biomes became increasingly water-limited and WUEe continued to increase until reaching a 'dry edge' threshold, a cross biome maximum WUEe, that cannot be sustained with further reductions in water availability and could potentially break down ecosystem resilience and induce

  16. Monitoring Ecosystem Quality and Function in Arid Settings of the Mojave Desert

    USGS Publications Warehouse

    Belnap, Jayne; Webb, Robert H.; Miller, Mark E.; Miller, David M.; DeFalco, Lesley A.; Medica, Philip A.; Brooks, Matthew L.; Esque, Todd C.; Bedford, Dave

    2008-01-01

    Monitoring ecosystem quality and function in the Mojave Desert is both a requirement of state and Federal government agencies and a means for determining potential long-term changes induced by climatic fluctuations and land use. Because it is not feasible to measure every attribute and process in the desert ecosystem, the choice of what to measure and where to measure it is the most important starting point of any monitoring program. In the Mojave Desert, ecosystem function is strongly influenced by both abiotic and biotic factors, and an understanding of the temporal and spatial variability induced by climate and landform development is needed to determine where site-specific measurements should be made. We review a wide variety of techniques for sampling, assessing, and measuring climatic variables, desert soils, biological soil crusts, annual and perennial vegetation, reptiles, and small mammals. The complete array of ecosystem attributes and processes that we describe are unlikely to be measured or monitored at any given location, but the array of possibilities allows for the development of specific monitoring protocols, which can be tailored to suit the needs of land-management agencies.

  17. Microbial functional diversity enhances predictive models linking environmental parameters to ecosystem properties.

    PubMed

    Powell, Jeff R; Welsh, Allana; Hallin, Sara

    2015-07-01

    Microorganisms drive biogeochemical processes, but linking these processes to real changes in microbial communities under field conditions is not trivial. Here, we present a model-based approach to estimate independent contributions of microbial community shifts to ecosystem properties. The approach was tested empirically, using denitrification potential as our model process, in a spatial survey of arable land encompassing a range of edaphic conditions and two agricultural production systems. Soil nitrate was the most important single predictor of denitrification potential (the change in Akaike's information criterion, corrected for sample size, ΔAIC(c) = 20.29); however, the inclusion of biotic variables (particularly the evenness and size of denitrifier communities [ΔAIC(c) = 12.02], and the abundance of one denitrifier genotype [ΔAIC(c) = 18.04]) had a substantial effect on model precision, comparable to the inclusion of abiotic variables (biotic R2 = 0.28, abiotic R2 = 0.50, biotic + abiotic R2 = 0.76). This approach provides a valuable tool for explicitly linking microbial communities to ecosystem functioning. By making this link, we have demonstrated that including aspects of microbial community structure and diversity in biogeochemical models can improve predictions of nutrient cycling in ecosystems and enhance our understanding of ecosystem functionality.

  18. Feedbacks Between Microenvironment and Plant Functional Type and Implications for CO2 Flux in Arctic Ecosystems

    NASA Astrophysics Data System (ADS)

    Squires, E.; Rodenheizer, H.; Natali, S.; Mann, P.

    2013-12-01

    Future climate models predict a warmer, drier Arctic, with resultant shifts in vegetative composition and implications for ecosystem carbon budgets. The impact of vegetation change, however, may depend on which plant functional groups are favored in a warming Arctic. Physiological and functional differences between plant groups influence both the local microenvironment and, on a broader scale, whole-ecosystem CO2 flux. We examined the interactions between plants and their microenvironment, and analyzed the effect of these interactions on both soil microbial communities and CO2 flux across different functional groups. Physical and biological aspects of the microenvironment differed between plant functional groups. Lichen patches were characterized by deeper thaw depths, lower soil moisture, greater thermal conductivity, and a thinner organic layer than mosses. To better understand the development of these plant-environment interactions, we conducted a reciprocal transplant experiment, switching multiple lichen and moss patches. Temporal changes in environmental parameters at these sites will demonstrate how different plants modify their environment and will help identify associated implications for soil microbial communities and CO2 flux. We measured CO2 flux and used Biolog assays to examine soil microbial communities in undisturbed patches of mosses, lichens, and shrubs. Patches of birch shrubs had more negative net ecosystem exchange, signifying a carbon sink. Soils from alder shrubs and mosses hosted more active microbial communities than soils under birch shrubs and lichens. These results suggest a strong link between environment, plant functional type, and C cycling. Understanding how this relationship differs among plant functional types is an important part of predicting ecosystem carbon budgets as Arctic vegetation composition shifts in response to climate change.

  19. Plant diversity and functional groups affect Si and Ca pools in aboveground biomass of grassland systems.

    PubMed

    Schaller, Jörg; Roscher, Christiane; Hillebrand, Helmut; Weigelt, Alexandra; Oelmann, Yvonne; Wilcke, Wolfgang; Ebeling, Anne; Weisser, Wolfgang W

    2016-09-01

    Plant diversity is an important driver of nitrogen and phosphorus stocks in aboveground plant biomass of grassland ecosystems, but plant diversity effects on other elements also important for plant growth are less understood. We tested whether plant species richness, functional group richness or the presence/absence of particular plant functional groups influences the Si and Ca concentrations (mmol g(-1)) and stocks (mmol m(-2)) in aboveground plant biomass in a large grassland biodiversity experiment (Jena Experiment). In the experiment including 60 temperate grassland species, plant diversity was manipulated as sown species richness (1, 2, 4, 8, 16) and richness and identity of plant functional groups (1-4; grasses, small herbs, tall herbs, legumes). We found positive species richness effects on Si as well as Ca stocks that were attributable to increased biomass production. The presence of particular functional groups was the most important factor explaining variation in aboveground Si and Ca stocks (mmol m(-2)). Grass presence increased the Si stocks by 140 % and legume presence increased the Ca stock by 230 %. Both the presence of specific plant functional groups and species diversity altered Si and Ca stocks, whereas Si and Ca concentration were affected mostly by the presence of specific plant functional groups. However, we found a negative effect of species diversity on Si and Ca accumulation, by calculating the deviation between mixtures and mixture biomass proportions, but in monoculture concentrations. These changes may in turn affect ecosystem processes such as plant litter decomposition and nutrient cycling in grasslands.

  20. Plant diversity and functional groups affect Si and Ca pools in aboveground biomass of grassland systems.

    PubMed

    Schaller, Jörg; Roscher, Christiane; Hillebrand, Helmut; Weigelt, Alexandra; Oelmann, Yvonne; Wilcke, Wolfgang; Ebeling, Anne; Weisser, Wolfgang W

    2016-09-01

    Plant diversity is an important driver of nitrogen and phosphorus stocks in aboveground plant biomass of grassland ecosystems, but plant diversity effects on other elements also important for plant growth are less understood. We tested whether plant species richness, functional group richness or the presence/absence of particular plant functional groups influences the Si and Ca concentrations (mmol g(-1)) and stocks (mmol m(-2)) in aboveground plant biomass in a large grassland biodiversity experiment (Jena Experiment). In the experiment including 60 temperate grassland species, plant diversity was manipulated as sown species richness (1, 2, 4, 8, 16) and richness and identity of plant functional groups (1-4; grasses, small herbs, tall herbs, legumes). We found positive species richness effects on Si as well as Ca stocks that were attributable to increased biomass production. The presence of particular functional groups was the most important factor explaining variation in aboveground Si and Ca stocks (mmol m(-2)). Grass presence increased the Si stocks by 140 % and legume presence increased the Ca stock by 230 %. Both the presence of specific plant functional groups and species diversity altered Si and Ca stocks, whereas Si and Ca concentration were affected mostly by the presence of specific plant functional groups. However, we found a negative effect of species diversity on Si and Ca accumulation, by calculating the deviation between mixtures and mixture biomass proportions, but in monoculture concentrations. These changes may in turn affect ecosystem processes such as plant litter decomposition and nutrient cycling in grasslands. PMID:27164912

  1. Advancing biodiversity-ecosystem functioning science using high-density tree-based experiments over functional diversity gradients.

    PubMed

    Tobner, Cornelia M; Paquette, Alain; Reich, Peter B; Gravel, Dominique; Messier, Christian

    2014-03-01

    Increasing concern about loss of biodiversity and its effects on ecosystem functioning has triggered a series of manipulative experiments worldwide, which have demonstrated a general trend for ecosystem functioning to increase with diversity. General mechanisms proposed to explain diversity effects include complementary resource use and invoke a key role for species' functional traits. The actual mechanisms by which complementary resource use occurs remain, however, poorly understood, as well as whether they apply to tree-dominated ecosystems. Here we present an experimental approach offering multiple innovative aspects to the field of biodiversity-ecosystem functioning (BEF) research. The International Diversity Experiment Network with Trees (IDENT) allows research to be conducted at several hierarchical levels within individuals, neighborhoods, and communities. The network investigates questions related to intraspecific trait variation, complementarity, and environmental stress. The goal of IDENT is to identify some of the mechanisms through which individuals and species interact to promote coexistence and the complementary use of resources. IDENT includes several implemented and planned sites in North America and Europe, and uses a replicated design of high-density tree plots of fixed species-richness levels varying in functional diversity (FD). The design reduces the space and time needed for trees to interact allowing a thorough set of mixtures varying over different diversity gradients (specific, functional, phylogenetic) and environmental conditions (e.g., water stress) to be tested in the field. The intention of this paper is to share the experience in designing FD-focused BEF experiments with trees, to favor collaborations and expand the network to different conditions. PMID:24241640

  2. Decade time scale plot to landscape scale change in tundra ecosystem structure and function near Barrow, AK

    NASA Astrophysics Data System (ADS)

    Lin, D. H.; Johnson, D. R.; Lara, M. J.; Villarreal, S.; Hollister, R. D.; Webber, P. J.; Tweedie, C. E.

    2012-12-01

    Several models suggest shifts in tundra ecosystem structure and function are likely to affect the future state of the Arctic system and how these shifts may impact the global system. Validation of such predictions remains a challenge, however, due to the lack of sustained environmental observations throughout much of the Arctic. In the absence of sustained monitoring, relocating, rescuing, and retrospectively resampling historic research sites and datasets has proven to be an effective means to establish likely change scenarios and develop hypotheses of future change trajectories. This study, synthesizes several recently published works that have used this retrospective approach to explore plot to landscape change in tundra ecosystem structure and function near Barrow, Alaska over the past half Century. This study is a contribution to the International Polar Year 'Back to the Future' project IPY-BTF, IPY # 512). At the landscape level, analysis of land cover change of time series high spatial resolution aerial and satellite imagery spanning 1948-2008 show an overall increase in the extent of dry and moist land cover and open water, and a decrease in the extent of wet and aquatic, land cover types. The 'drying' trend noted for the coastal landscape of Barrow is similar to that noted for four other Alaskan tundra landscapes but in the same study, the Barrow landscape also showed the most dramatic change in wet and aquatic land cover types. Plot level studies of sites, established in 1972 during the International Biological Program, that have been resampled three times show that species richness and diversity has increased and that wet plant communities have changed more than dry plant communities. An analysis of ecosystem function coupled to this plot level study suggests the greatest functional change has occurred in aquatic and wet plant communities where methane efflux and net ecosystem production (NEP) has increased and albedo and the normalized difference

  3. Quantifying the pedo-ecohydrological structure and function of degraded, grassland ecosystems

    NASA Astrophysics Data System (ADS)

    Brazier, Richard E.

    2015-04-01

    Grassland ecosystems cover significant areas of the terrestrial land mass, across a range of geoclimates, from arctic tundra, through temperate and semi-arid landscapes. In very few locations, such grasslands may be termed 'pristine' in that they remain undamaged by human activities and resilient to changing climates. In far more cases, grasslands are being degraded, often irreversibly so, with significant implications for a number of ecosystem services related to water resources, soil quality, nutrient cycles, and therefore both global food and water security. This paper draws upon empirical research that has been undertaken over the last decade to characterise a range of different grasslands in terms of soil properties, vegetation structure and geomorphology and to understand how these structures or patterns might interact or control how the grassland ecosystems function. Particular emphasis is placed upon quantifying fluxes of water, within and from grasslands, but also fluxes of sediment, via the processes of soil erosion and finally fluxes of the macronutrients Nitrogen, Phosphorus and Carbon from the landscape to surface waters. Data are presented from semi-arid grasslands, which are subject to severe encroachment by woody species, temperate upland grasslands that have been 'improved' via drainage to support grazing, temperate lowland grasslands, that are unimproved (Culm or Rhôs pastures) and finally intensively managed grasslands in temperate regions, that have been significantly modified via land management practices to improve productivity. It is hypothesised that, once degraded, the structure and function of these very diverse grassland ecosystems follows the same negative trajectory, resulting in depleted soil depths, nutrient storage capacities and therefore reduced plant growth and long-term carbon sequestration. Results demonstrate that similar, but highly complex and non-linear responses to perturbation of the ecosystem are observed, regardless of

  4. Protecting marine biodiversity to preserve ecosystem functioning: A tribute to Carlo Heip

    NASA Astrophysics Data System (ADS)

    Herman, Peter; Warwick, Richard; Aller, Robert; Arvanitidis, Christos; Hewitt, Judi; Stal, Lucas; Vincx, Magda

    2015-04-01

    Carlo Heip was the highly respected Editor-In-Chief of the Journal of Sea Research until his untimely death on 15 February 2013. As a tribute, the Journal wished to organize a special volume in his honour, the scope of which would provide an overview of the current state of affairs and the future outlook of marine biodiversity, a field of research to which Carlo made a major contribution. The volume places special emphasis on how marine biodiversity links to ecosystem functioning. Authors were invited to address such issues as: Which ecosystem functions are vulnerable to loss of biodiversity and how is the relation causally structured? How do trophic and non-trophic networks in ecosystems function and how do they depend on biodiversity? What is the role of spatial structuring for biodiversity? What is the role of biodiversity in biogeochemical fluxes at different scales? What are the new frontiers in the study of marine biodiversity and how can functional aspects be integrated in them? In this approach we wanted to cover a broad range of organisms reflecting Carlo's interests, the whole marine area from coastal systems to the deep sea, and spatial scales from single locations to worldwide databases.

  5. Convergence of the effect of root hydraulic functioning and root hydraulic redistribution on ecosystem water and carbon balance across divergent forest ecosystems

    NASA Astrophysics Data System (ADS)

    domec, J.; King, J. S.; Ogée, J.; Noormets, A.; Warren, J.; Meinzer, F. C.; Sun, G.; Jordan-Meille, L.; Martineau, E.; Brooks, R. J.; Laclau, J.; Battie Laclau, P.; McNulty, S.

    2012-12-01

    INVITED ABSTRACT: Deep root water uptake and hydraulic redistribution (HR) play a major role in forest ecosystems during drought, but little is known about the impact of climate change on root-zone processes influencing HR and its consequences on water and carbon fluxes. Using data from two old growth sites in the western USA, two mature sites in the eastern USA, one site in southern Brazil, and simulations with the process-based model MuSICA, our objectives were to show that HR can 1) mitigate the effects of soil drying on root functioning, and 2) have important implications for carbon uptake and net ecosystem exchange (NEE). In a dry, old-growth ponderosa pine (USA) and a eucalyptus stand (Brazil) both characterized by deep sandy soils, HR limited the decline in root hydraulic conductivity and increased dry season tree transpiration (T) by up to 30%, which impacted NEE through major increases in gross primary productivity (GPP). The presence of deep-rooted trees did not necessarily imply high rates of HR unless soil texture allowed large water potential gradients to occur, as was the case in the wet old-growth Douglas-fir/mixed conifer stand. At the Duke mixed hardwood forest characterized by a shallow clay-loam soil, modeled HR was low but not negligible, representing annually up to 10% of T, and maintaining root conductance high. At this site, in the absence of HR, it was predicted that annual GPP would have been diminished by 7-19%. At the coastal loblolly pine plantation, characterized by deep organic soil, HR limited the decline in shallow root conductivity by more than 50% and increased dry season T by up to 40%, which increased net carbon gain by the ecosystem by about 400 gC m-2 yr-1, demonstrating the significance of HR in maintaining the stomatal conductance and assimilation capacity of the whole ecosystem. Under future climate conditions (elevated atmospheric [CO2] and temperature), HR is predicted to be reduced by up to 50%; reducing the resilience of

  6. Bacterial structures and ecosystem functions in glaciated floodplains: contemporary states and potential future shifts.

    PubMed

    Freimann, Remo; Bürgmann, Helmut; Findlay, Stuart E G; Robinson, Christopher T

    2013-12-01

    Glaciated alpine floodplains are responding quickly to climate change through shrinking ice masses. Given the expected future changes in their physicochemical environment, we anticipated variable shifts in structure and ecosystem functioning of hyporheic microbial communities in proglacial alpine streams, depending on present community characteristics and landscape structures. We examined microbial structure and functioning during different hydrologic periods in glacial (kryal) streams and, as contrasting systems, groundwater-fed (krenal) streams. Three catchments were chosen to cover an array of landscape features, including interconnected lakes, differences in local geology and degree of deglaciation. Community structure was assessed by automated ribosomal intergenic spacer analysis and microbial function by potential enzyme activities. We found each catchment to contain a distinct bacterial community structure and different degrees of separation in structure and functioning that were linked to the physicochemical properties of the waters within each catchment. Bacterial communities showed high functional plasticity, although achieved by different strategies in each system. Typical kryal communities showed a strong linkage of structure and function that indicated a major prevalence of specialists, whereas krenal sediments were dominated by generalists. With the rapid retreat of glaciers and therefore altered ecohydrological characteristics, lotic microbial structure and functioning are likely to change substantially in proglacial floodplains in the future. The trajectory of these changes will vary depending on contemporary bacterial community characteristics and landscape structures that ultimately determine the sustainability of ecosystem functioning.

  7. Stress differentially impacts reserve pools and root exudation: implications for ecosystem functioning and carbon balance

    NASA Astrophysics Data System (ADS)

    Landhäusser, Simon; Karst, Justine; Wiley, Erin; Gaster, Jacob

    2016-04-01

    Environmental stress can influence carbon assimilation and the accumulation and distribution of carbon between growth, reserves, and exudation; however, it is unclear how these processes vary by different stress types. Partitioning of carbon to growth and reserves in plants might also vary between different organs. Roots reserves are of particular interest as they link the plant with the soil carbon cycle through exudation. Simple models of diffusion across concentration gradients predict the more C reserves in roots, the more C should be exuded from roots. However, the mechanisms underlying the accumulation and loss of C from roots may differ depending on the stress experienced by the plants. In a controlled study we tested whether different types of stresses (shade, cold soil, and drought) have differential effects on the distribution, abundance, and form (sugar vs. starch) of carbohydrates in seedlings, and whether these changes alone could explain differences in root exudation between stress types. Non-structural carbohydrate (NSC) concentration and pool sizes varied by stress type and between organs. Mass-specific C exudation increased with fine root sugar concentration; however, stress type affected exudation independently of reserve concentration. Seedlings exposed to cold soils exuded the most C on a per root mass basis followed by shade and drought. Through 13C labeling, we also found that depending on the stress type, aspen seedlings may be less able to control the loss of C to the soil compared with unstressed seedlings, resulting in more C leaked to the rhizosphere. The loss of C beyond that predicted by simple concentration gradients might have important implications for ecosystem functioning and carbon balance. If stressed plants lose proportionally more carbon to the soil, existing interactions between plants and soils may decouple under stress, and may include unexpected C fluxes between trees, soils and the atmosphere with a changing climate.

  8. The assessment of a global marine ecosystem model on the basis of emergent properties and ecosystem function: a case study with ERSEM

    NASA Astrophysics Data System (ADS)

    de Mora, L.; Butenschön, M.; Allen, J. I.

    2016-01-01

    Ecosystem models are often assessed using quantitative metrics of absolute ecosystem state, but these model-data comparisons are disproportionately vulnerable to discrepancies in the location of important circulation features. An alternative method is to demonstrate the models capacity to represent ecosystem function; the emergence of a coherent natural relationship in a simulation indicates that the model may have an appropriate representation of the ecosystem functions that lead to the emergent relationship. Furthermore, as emergent properties are large-scale properties of the system, model validation with emergent properties is possible even when there is very little or no appropriate data for the region under study, or when the hydrodynamic component of the model differs significantly from that observed in nature at the same location and time.

    A selection of published meta-analyses are used to establish the validity of a complex marine ecosystem model and to demonstrate the power of validation with emergent properties. These relationships include the phytoplankton community structure, the ratio of carbon to chlorophyll in phytoplankton and particulate organic matter, the ratio of particulate organic carbon to particulate organic nitrogen and the stoichiometric balance of the ecosystem.

    These metrics can also inform aspects of the marine ecosystem model not available from traditional quantitative and qualitative methods. For instance, these emergent properties can be used to validate the design decisions of the model, such as the range of phytoplankton functional types and their behaviour, the stoichiometric flexibility with regards to each nutrient, and the choice of fixed or variable carbon to nitrogen ratios.

  9. Consequences of a simulated rapid ocean acidification event for benthic ecosystem processes and functions.

    PubMed

    Murray, Fiona; Widdicombe, Stephen; McNeill, C Louise; Solan, Martin

    2013-08-30

    Whilst the biological consequences of long-term, gradual changes in acidity associated with the oceanic uptake of atmospheric carbon dioxide (CO2) are increasingly studied, the potential effects of rapid acidification associated with a failure of sub-seabed carbon storage infrastructure have received less attention. This study investigates the effects of severe short-term (8days) exposure to acidified seawater on infaunal mediation of ecosystem processes (bioirrigation and sediment particle redistribution) and functioning (nutrient concentrations). Following acidification, individuals of Amphiura filiformis exhibited emergent behaviour typical of a stress response, which resulted in altered bioturbation, but limited changes in nutrient cycling. Under acidified conditions, A. filiformis moved to shallower depths within the sediment and the variability in occupancy depth reduced considerably. This study indicated that rapid acidification events may not be lethal to benthic invertebrates, but may result in behavioural changes that could have longer-term implications for species survival, ecosystem structure and functioning.

  10. Proliferation of Purple Sulphur Bacteria at the Sediment Surface Affects Intertidal Mat Diversity and Functionality

    PubMed Central

    Hubas, Cédric; Jesus, Bruno; Ruivo, Mickael; Meziane, Tarik; Thiney, Najet; Davoult, Dominique; Spilmont, Nicolas; Paterson, David M.; Jeanthon, Christian

    2013-01-01

    There is a relative absence of studies dealing with mats of purple sulphur bacteria in the intertidal zone. These bacteria display an array of metabolic pathways that allow them to disperse and develop under a wide variety of conditions, making these mats important in terms of ecosystem processes and functions. Mass blooms of purple sulphur bacteria develop during summer on sediments in the intertidal zone especially on macroalgal deposits. The microbial composition of different types of mats differentially affected by the development of purple sulphur bacteria was examined, at low tide, using a set of biochemical markers (fatty acids, pigments) and composition was assessed against their influence on ecosystem functions (sediment cohesiveness, CO2 fixation). We demonstrated that proliferation of purple sulphur bacteria has a major impact on intertidal mats diversity and functions. Indeed, assemblages dominated by purple sulphur bacteria (Chromatiaceae) were efficient exopolymer producers and their biostabilisation potential was significant. In addition, the massive growth of purple sulphur bacteria resulted in a net CO2 degassing whereas diatom dominated biofilms represented a net CO2 sink. PMID:24340018

  11. Environmental Drivers of Benthic Flux Variation and Ecosystem Functioning in Salish Sea and Northeast Pacific Sediments.

    PubMed

    Belley, Rénald; Snelgrove, Paul V R; Archambault, Philippe; Juniper, S Kim

    2016-01-01

    The upwelling of deep waters from the oxygen minimum zone in the Northeast Pacific from the continental slope to the shelf and into the Salish Sea during spring and summer offers a unique opportunity to study ecosystem functioning in the form of benthic fluxes along natural gradients. Using the ROV ROPOS we collected sediment cores from 10 sites in May and July 2011, and September 2013 to perform shipboard incubations and flux measurements. Specifically, we measured benthic fluxes of oxygen and nutrients to evaluate potential environmental drivers of benthic flux variation and ecosystem functioning along natural gradients of temperature and bottom water dissolved oxygen concentrations. The range of temperature and dissolved oxygen encountered across our study sites allowed us to apply a suite of multivariate analyses rarely used in flux studies to identify bottom water temperature as the primary environmental driver of benthic flux variation and organic matter remineralization. Redundancy analysis revealed that bottom water characteristics (temperature and dissolved oxygen), quality of organic matter (chl a:phaeo and C:N ratios) and sediment characteristics (mean grain size and porosity) explained 51.5% of benthic flux variation. Multivariate analyses identified significant spatial and temporal variation in benthic fluxes, demonstrating key differences between the Northeast Pacific and Salish Sea. Moreover, Northeast Pacific slope fluxes were generally lower than shelf fluxes. Spatial and temporal variation in benthic fluxes in the Salish Sea were driven primarily by differences in temperature and quality of organic matter on the seafloor following phytoplankton blooms. These results demonstrate the utility of multivariate approaches in differentiating among potential drivers of seafloor ecosystem functioning, and indicate that current and future predictive models of organic matter remineralization and ecosystem functioning of soft-muddy shelf and slope seafloor

  12. Environmental Drivers of Benthic Flux Variation and Ecosystem Functioning in Salish Sea and Northeast Pacific Sediments

    PubMed Central

    Belley, Rénald; Snelgrove, Paul V. R.; Archambault, Philippe; Juniper, S. Kim

    2016-01-01

    The upwelling of deep waters from the oxygen minimum zone in the Northeast Pacific from the continental slope to the shelf and into the Salish Sea during spring and summer offers a unique opportunity to study ecosystem functioning in the form of benthic fluxes along natural gradients. Using the ROV ROPOS we collected sediment cores from 10 sites in May and July 2011, and September 2013 to perform shipboard incubations and flux measurements. Specifically, we measured benthic fluxes of oxygen and nutrients to evaluate potential environmental drivers of benthic flux variation and ecosystem functioning along natural gradients of temperature and bottom water dissolved oxygen concentrations. The range of temperature and dissolved oxygen encountered across our study sites allowed us to apply a suite of multivariate analyses rarely used in flux studies to identify bottom water temperature as the primary environmental driver of benthic flux variation and organic matter remineralization. Redundancy analysis revealed that bottom water characteristics (temperature and dissolved oxygen), quality of organic matter (chl a:phaeo and C:N ratios) and sediment characteristics (mean grain size and porosity) explained 51.5% of benthic flux variation. Multivariate analyses identified significant spatial and temporal variation in benthic fluxes, demonstrating key differences between the Northeast Pacific and Salish Sea. Moreover, Northeast Pacific slope fluxes were generally lower than shelf fluxes. Spatial and temporal variation in benthic fluxes in the Salish Sea were driven primarily by differences in temperature and quality of organic matter on the seafloor following phytoplankton blooms. These results demonstrate the utility of multivariate approaches in differentiating among potential drivers of seafloor ecosystem functioning, and indicate that current and future predictive models of organic matter remineralization and ecosystem functioning of soft-muddy shelf and slope seafloor

  13. Research needs to better understand Lake Ontario ecosystem function: A workshop summary

    USGS Publications Warehouse

    Stewart, Thomas J.; Rudstam, Lars G.; Watkins, James M.; Johnson, Timothy B.; Weidel, Brian C.; Koops, Marten A.

    2016-01-01

    Lake Ontario investigators discussed and interpreted published and unpublished information during two workshops to assess our current understanding of Lake Ontario ecosystem function and to identify research needs to guide future research and monitoring activities. The purpose of this commentary is to summarize key investigative themes and hypotheses that emerged from the workshops. The outcomes of the workshop discussions are organized under four themes: spatial linkages and interactions, drivers of primary production, trophic transfer, and human interactions.

  14. Ecosystems: development, functions and consequences of disturbances, with special reference to the oral cavity.

    PubMed

    Midtvedt, T

    1990-08-01

    Some general rules for the development and maintenance of microbial ecosystems are outlined. Studies on germ-free animals have given valuable baselines concerning structures and functions in the host per se. The oral cavity represents several consortia of micro-organisms, governed by factors deriving from the host, the diet and/or the micro-organisms. Alterations in these factors, as well as intake of antibiotics, etc., may give disturbances, which can be analyzed according to general guidelines. PMID:2391384

  15. Ecosystem services of Phragmites in North America with emphasis on habitat functions

    PubMed Central

    Kiviat, Erik

    2013-01-01

    Phragmites australis (common reed) is widespread in North America, with native and non-native haplotypes. Many ecologists and wetland managers have considered P. australis a weed with little value to the native biota or human society. I document important ecosystem services of Phragmites including support for many common and rare species of plants and animals. This paper is based on an extensive review of the ecology and natural history literature, discussions with field workers, and observations in 13 US states and one Canadian province during the past 40 years. Phragmites sequesters nutrients, heavy metals and carbon, builds and stabilizes soils, and creates self-maintaining vegetation in urban and industrial areas where many plants do not thrive. These non-habitat ecosystem services are proportional to biomass and productivity. Phragmites was widely used by Native Americans for many purposes; the most important current direct use is for the treatment of wastes. Most of the knowledge of non-habitat ecosystem services is based on studies of P. australis haplotype M (an Old World haplotype). Phragmites also has habitat functions for many organisms. These functions depend on the characteristics of the landscape, habitat, Phragmites stand, species using Phragmites and life history element. The functions that Phragmites provides for many species are optimal at lower levels of Phragmites biomass and extent of stands. Old World Phragmites, contrary to many published statements, as well as North American native Phragmites, provide valuable ecosystem services including products for human use and habitat functions for other organisms. Phragmites stands may need management (e.g. thinning, fragmentation, containment or removal) to create or maintain suitable habitat for desired species of animals and plants.

  16. Quantifying the pedo-ecohydrological structure and function of degraded, grassland ecosystems

    NASA Astrophysics Data System (ADS)

    Brazier, Richard E.

    2015-04-01

    Grassland ecosystems cover significant areas of the terrestrial land mass, across a range of geoclimates, from arctic tundra, through temperate and semi-arid landscapes. In very few locations, such grasslands may be termed 'pristine' in that they remain undamaged by human activities and resilient to changing climates. In far more cases, grasslands are being degraded, often irreversibly so, with significant implications for a number of ecosystem services related to water resources, soil quality, nutrient cycles, and therefore both global food and water security. This paper draws upon empirical research that has been undertaken over the last decade to characterise a range of different grasslands in terms of soil properties, vegetation structure and geomorphology and to understand how these structures or patterns might interact or control how the grassland ecosystems function. Particular emphasis is placed upon quantifying fluxes of water, within and from grasslands, but also fluxes of sediment, via the processes of soil erosion and finally fluxes of the macronutrients Nitrogen, Phosphorus and Carbon from the landscape to surface waters. Data are presented from semi-arid grasslands, which are subject to severe encroachment by woody species, temperate upland grasslands that have been 'improved' via drainage to support grazing, temperate lowland grasslands, that are unimproved (Culm or Rhôs pastures) and finally intensively managed grasslands in temperate regions, that have been significantly modified via land management practices to improve productivity. It is hypothesised that, once degraded, the structure and function of these very diverse grassland ecosystems follows the same negative trajectory, resulting in depleted soil depths, nutrient storage capacities and therefore reduced plant growth and long-term carbon sequestration. Results demonstrate that similar, but highly complex and non-linear responses to perturbation of the ecosystem are observed, regardless of

  17. Tropical marginal seas: priority regions for managing marine biodiversity and ecosystem function.

    PubMed

    McKinnon, A David; Williams, Alan; Young, Jock; Ceccarelli, Daniela; Dunstan, Piers; Brewin, Robert J W; Watson, Reg; Brinkman, Richard; Cappo, Mike; Duggan, Samantha; Kelley, Russell; Ridgway, Ken; Lindsay, Dhugal; Gledhill, Daniel; Hutton, Trevor; Richardson, Anthony J

    2014-01-01

    Tropical marginal seas (TMSs) are natural subregions of tropical oceans containing biodiverse ecosystems with conspicuous, valued, and vulnerable biodiversity assets. They are focal points for global marine conservation because they occur in regions where human populations are rapidly expanding. Our review of 11 TMSs focuses on three key ecosystems-coral reefs and emergent atolls, deep benthic systems, and pelagic biomes-and synthesizes, illustrates, and contrasts knowledge of biodiversity, ecosystem function, interaction between adjacent habitats, and anthropogenic pressures. TMSs vary in the extent that they have been subject to human influence-from the nearly pristine Coral Sea to the heavily exploited South China and Caribbean Seas-but we predict that they will all be similarly complex to manage because most span multiple national jurisdictions. We conclude that developing a structured process to identify ecologically and biologically significant areas that uses a set of globally agreed criteria is a tractable first step toward effective multinational and transboundary ecosystem management of TMSs. PMID:24128091

  18. Food web pathway determines how selenium affects aquatic ecosystems: a San Francisco Bay case study.

    PubMed

    Stewart, A Robin; Luoma, Samuel N; Schlekat, Christian E; Doblin, Martina A; Hieb, Kathryn A

    2004-09-01

    Chemical contaminants disrupt ecosystems, but specific effects may be under-appreciated when poorly known processes such as uptake mechanisms, uptake via diet, food preferences, and food web dynamics are influential. Here we show that a combination of food web structure and the physiology of trace element accumulation explain why some species in San Francisco Bay are threatened by a relatively low level of selenium contamination and some are not. Bivalves and crustacean zooplankton form the base of two dominant food webs in estuaries. The dominant bivalve Potamocorbula amurensis has a 10-fold slower rate constant of loss for selenium than do common crustaceans such as copepods and the mysid Neomysis mercedis (rate constant of loss, ke = 0.025, 0.155, and 0.25 d(-1), respectively). The result is much higher selenium concentrations in the bivalve than in the crustaceans. Stable isotope analyses show that this difference is propagated up the respective food webs in San Francisco Bay. Several predators of bivalves have tissue concentrations of selenium that exceed thresholds thought to be associated with teratogenesis or reproductive failure (liver Se >15 microg g(-1) dry weight). Deformities typical of selenium-induced teratogenesis were observed in one of these species. Concentrations of selenium in tissues of predators of zooplankton are less than the thresholds. Basic physiological and ecological processes can drive wide differences in exposure and effects among species, but such processes are rarely considered in traditional evaluations of contaminant impacts. PMID:15461158

  19. Food web pathway determines how selenium affects aquatic ecosystems: A San francisco Bay case study

    USGS Publications Warehouse

    Stewart, A.R.; Luoma, S.N.; Schlekat, C.E.; Doblin, M.A.; Hieb, K.A.

    2004-01-01

    Chemical contaminants disrupt ecosystems, but specific effects may be under-appreciated when poorly known processes such as uptake mechanisms, uptake via diet, food preferences, and food web dynamics are influential. Here we show that a combination of food web structure and the physiology of trace element accumulation explain why some species in San Francisco Bay are threatened by a relatively low level of selenium contamination and some are not. Bivalves and crustacean Zooplankton form the base of two dominant food webs in estuaries. The dominant bivalve Potamocorbula amurensis has a 10-fold slower rate constant of loss for selenium than do common crustaceans such as copepods and the mysid Neomysis mercedis (rate constant of loss, ke = 0.025, 0.155, and 0.25 d-1, respectively). The result is much higher selenium concentrations in the bivalve than in the crustaceans. Stable isotope analyses show that this difference is propagated up the respective food webs in San Francisco Bay. Several predators of bivalves have tissue concentrations of selenium that exceed thresholds thought to be associated with teratogenesis or reproductive failure (liver Se > 15 ??g g-1 dry weight). Deformities typical of selenium-induced teratogenesis were observed in one of these species. Concentrations of selenium in tissues of predators of Zooplankton are less than the thresholds. Basic physiological and ecological processes can drive wide differences in exposure and effects among species, but such processes are rarely considered in traditional evaluations of contaminant impacts.

  20. Oceanographic and behavioural processes affecting invertebrate larval dispersal and supply in the western Iberia upwelling ecosystem

    NASA Astrophysics Data System (ADS)

    Queiroga, Henrique; Cruz, Teresa; dos Santos, Antonina; Dubert, Jesus; González-Gordillo, Juan Ignácio; Paula, José; Peliz, Álvaro; Santos, A. Miguel P.

    2007-08-01

    The present review addresses recent findings made in the western Iberia ecosystem on the behavioural and physical interactions that regulate dispersal, supply to coastal habitats and settlement of invertebrate larvae. These studies used the barnacle Chthamalus spp. and the crab Carcinus maenas as model organisms. The observations made on the Iberian shelf showed extensive diel vertical migrations along the water column by representatives of both groups that have never been reported before. The interaction of the diel vertical migration with the two-layer flow structure of upwelling/downwelling circulation suggests a mechanism that may help to retain larvae in shelf waters during upwelling conditions. Measurements of daily supply of C. maenas megalopae to estuaries separated by 500 km disclosed a semilunar pattern, with highest supply around highest amplitude tides, indicating that supply of megalopae to estuaries is accomplished by selective tidal stream transport. Relaxation of equatorward winds also played a role in supply, by enhancing translocation of megalopae to the nearshore. Concerning Chthamalus larvae, the observations on daily settlement made at rocky shores also separated by 500 km showed unclear patterns between locations and years. The relationship of settlement with water temperature, tidal range and upwelling indices indicated that supply of barnacle cyprids may be controlled by multiple mechanisms, viz. upwelling/downwelling circulation, internal tidal bores and sea breezes.

  1. Bioaccumulation of mercury in benthic communities of a river ecosystem affected by mercury mining.

    PubMed

    Zizek, Suzana; Horvat, Milena; Gibicar, Darija; Fajon, Vesna; Toman, Mihael J

    2007-05-15

    The presence of mercury in the river Idrijca (Slovenia) is mainly due to 500 years of mercury mining in this region. In order to understand the cycling of mercury in the Idrijca ecosystem it is crucial to investigate the role of biota. This study is part of an ongoing investigation of mercury biogeochemistry in the river Idrijca, focusing on the accumulation and speciation of mercury in the lower levels of the food chain, namely filamentous algae, periphyton and macroinvertebrates. Mercury analysis and speciation in the biota and in water were performed during the spring, summer and autumn seasons at four locations on the river, representing different degrees of mercury contamination. Total (THg) and methyl mercury (MeHg) were measured. The results showed that the highest THg concentrations in biota correlate well with THg levels in sediments and water. The level of MeHg is spatially and seasonally variable, showing higher values at the most contaminated sites during the summer and autumn periods. The percentage of Hg as MeHg increases with the trophic level from water (0.1-0.8%), algae (0.5-1.3%), periphyton (1.6-8.8%) to macroinvertebrates (0.1-100%), which indicates active transformation, accumulation and magnification of mercury in the benthic organism of this heavily contaminated torrential river.

  2. Use of descriptors of ecosystem functioning for monitoring a national park network: a remote sensing approach.

    PubMed

    Alcaraz-Segura, Domingo; Cabello, Javier; Paruelo, José M; Delibes, Miguel

    2009-01-01

    Baseline assessments and monitoring of protected areas are essential for making management decisions, evaluating the effectiveness of management practices, and tracking the effects of global changes. For these purposes, the analysis of functional attributes of ecosystems (i.e., different aspects of the exchange of matter and energy) has advantages over the traditional use of structural attributes, like a quicker response to disturbances and the fact that they are easily monitored through remote sensing. In this study, we described the spatiotemporal patterns of different aspects of the ecosystem functioning of the Spanish national parks and their response to environmental changes between 1982 and 2006. To do so, we used the NOAA/AVHRR-GIMMS dataset of the Normalized Difference Vegetation Index (NDVI), a linear estimator of the fraction of photosynthetic active radiation intercepted by vegetation, which is the main control of carbon gains. Nearly all parks have significantly changed during the last 25 years: The radiation interception has increased, the contrast between the growing and nongrowing seasons has diminished, and the dates of maximum and minimum interception have advanced. Some parks concentrated more changes than others and the degree of change varied depending on their different environmental conditions, management, and conservation histories. Our approach identified reference conditions and temporal changes for different aspects of ecosystem functioning, which can be used for management purposes of protected areas in response to global changes.

  3. Trait-based approaches for understanding microbial biodiversity and ecosystem functioning

    PubMed Central

    Krause, Sascha; Le Roux, Xavier; Niklaus, Pascal A.; Van Bodegom, Peter M.; Lennon, Jay T.; Bertilsson, Stefan; Grossart, Hans-Peter; Philippot, Laurent; Bodelier, Paul L. E.

    2014-01-01

    In ecology, biodiversity-ecosystem functioning (BEF) research has seen a shift in perspective from taxonomy to function in the last two decades, with successful application of trait-based approaches. This shift offers opportunities for a deeper mechanistic understanding of the role of biodiversity in maintaining multiple ecosystem processes and services. In this paper, we highlight studies that have focused on BEF of microbial communities with an emphasis on integrating trait-based approaches to microbial ecology. In doing so, we explore some of the inherent challenges and opportunities of understanding BEF using microbial systems. For example, microbial biologists characterize communities using gene phylogenies that are often unable to resolve functional traits. Additionally, experimental designs of existing microbial BEF studies are often inadequate to unravel BEF relationships. We argue that combining eco-physiological studies with contemporary molecular tools in a trait-based framework can reinforce our ability to link microbial diversity to ecosystem processes. We conclude that such trait-based approaches are a promising framework to increase the understanding of microbial BEF relationships and thus generating systematic principles in microbial ecology and more generally ecology. PMID:24904563

  4. Tree species identity and functional traits but not species richness affect interrill erosion processes in young subtropical forests

    NASA Astrophysics Data System (ADS)

    Seitz, S.; Goebes, P.; Song, Z.; Bruelheide, H.; Härdtle, W.; Kühn, P.; Li, Y.; Scholten, T.

    2015-06-01

    Soil erosion is seriously threatening ecosystem functioning in many parts of the world. In this context, it is assumed that tree species richness and functional diversity of tree communities can play a critical role in improving ecosystem services such as erosion control. An experiment with 170 micro-scale runoff plots was conducted to investigate the influence of tree species richness and identity as well as tree functional traits on interrill erosion in a young forest ecosystem. An interrill erosion rate of 47.5 t ha-1 a-1 was calculated. This study provided evidence that different tree species affect interrill erosion, but higher tree species richness did not mitigate soil losses in young forest stands. Thus, different tree morphologies have to be considered, when assessing erosion under forest. High crown cover and leaf area index reduced soil losses in initial forest ecosystems, whereas rising tree height increased them. Even if a leaf litter cover was not present, remaining soil surface cover by stones and biological soil crusts was the most important driver for soil erosion control. Furthermore, soil organic matter had a decreasing influence on soil loss. Long-term monitoring of soil erosion under closing tree canopies is necessary and a wide range of functional tree traits should be taken into consideration in future research.

  5. Managed island ecosystems

    USGS Publications Warehouse

    McEachern, Kathryn; Atwater, Tanya; Collins, Paul W.; Faulkner, Kate R.; Richards, Daniel V.

    2016-01-01

    This long-anticipated reference and sourcebook for California’s remarkable ecological abundance provides an integrated assessment of each major ecosystem type—its distribution, structure, function, and management. A comprehensive synthesis of our knowledge about this biologically diverse state, Ecosystems of California covers the state from oceans to mountaintops using multiple lenses: past and present, flora and fauna, aquatic and terrestrial, natural and managed. Each chapter evaluates natural processes for a specific ecosystem, describes drivers of change, and discusses how that ecosystem may be altered in the future. This book also explores the drivers of California’s ecological patterns and the history of the state’s various ecosystems, outlining how the challenges of climate change and invasive species and opportunities for regulation and stewardship could potentially affect the state’s ecosystems. The text explicitly incorporates both human impacts and conservation and restoration efforts and shows how ecosystems support human well-being. Edited by two esteemed ecosystem ecologists and with overviews by leading experts on each ecosystem, this definitive work will be indispensable for natural resource management and conservation professionals as well as for undergraduate or graduate students of California’s environment and curious naturalists.

  6. Characterizing Zinc Speciation in Soils from a Smelter-Affected Boreal Forest Ecosystem.

    PubMed

    Hamilton, Jordan G; Farrell, Richard E; Chen, Ning; Feng, Renfei; Reid, Joel; Peak, Derek

    2016-03-01

    HudBay Minerals, Inc., has mined and/or processed Zn and Cu ore in Flin Flon, MB, Canada, since the 1930s. The boreal forest ecosystem and soil surrounding these facilities have been severely impacted by mixed metal contamination and HSO deposition. Zinc is one of the most prevalent smelter-derived contaminants and has been identified as a key factor that may be limiting revegetation. Metal toxicity is related to both total concentrations and speciation; therefore, X-ray absorption spectroscopy and X-ray fluorescence mapping were used to characterize Zn speciation in soils throughout the most heavily contaminated areas of the landscape. Zinc speciation was linked to two distinct soil types. Group I soils consist of exposed soils in weathered positions of bedrock outcrops with Zn present primarily as franklinite, a (ZnFeO) spinel mineral. Group II soils are stabilized by an invasive metal-tolerant grass species, with Zn found as a mixture of octahedral (Fe oxides) and tetrahedral Mn oxides) adsorption complexes with a franklinite component. Soil erosion influences Zn speciation through the redistribution of Zn and soil particulates from Group I landscape positions to Group II soils. Despite Group II soils having the highest concentrations of CaCl-extractable Zn, they support metal-tolerant plant growth. The metal-tolerant plants are probably preferentially colonizing these areas due to better soil and nutrient conditions as a result of soil deposition from upslope Group I areas. Zinc concentration and speciation appears to not influence the colonization by metal-tolerant grasses, but the overall soil properties and erosion effects prevent the revegetation by native boreal forest species. PMID:27065416

  7. Climate change and Southern Ocean ecosystems I: how changes in physical habitats directly affect marine biota.

    PubMed

    Constable, Andrew J; Melbourne-Thomas, Jessica; Corney, Stuart P; Arrigo, Kevin R; Barbraud, Christophe; Barnes, David K A; Bindoff, Nathaniel L; Boyd, Philip W; Brandt, Angelika; Costa, Daniel P; Davidson, Andrew T; Ducklow, Hugh W; Emmerson, Louise; Fukuchi, Mitsuo; Gutt, Julian; Hindell, Mark A; Hofmann, Eileen E; Hosie, Graham W; Iida, Takahiro; Jacob, Sarah; Johnston, Nadine M; Kawaguchi, So; Kokubun, Nobuo; Koubbi, Philippe; Lea, Mary-Anne; Makhado, Azwianewi; Massom, Rob A; Meiners, Klaus; Meredith, Michael P; Murphy, Eugene J; Nicol, Stephen; Reid, Keith; Richerson, Kate; Riddle, Martin J; Rintoul, Stephen R; Smith, Walker O; Southwell, Colin; Stark, Jonathon S; Sumner, Michael; Swadling, Kerrie M; Takahashi, Kunio T; Trathan, Phil N; Welsford, Dirk C; Weimerskirch, Henri; Westwood, Karen J; Wienecke, Barbara C; Wolf-Gladrow, Dieter; Wright, Simon W; Xavier, Jose C; Ziegler, Philippe

    2014-10-01

    Antarctic and Southern Ocean (ASO) marine ecosystems have been changing for at least the last 30 years, including in response to increasing ocean temperatures and changes in the extent and seasonality of sea ice; the magnitude and direction of these changes differ between regions around Antarctica that could see populations of the same species changing differently in different regions. This article reviews current and expected changes in ASO physical habitats in response to climate change. It then reviews how these changes may impact the autecology of marine biota of this polar region: microbes, zooplankton, salps, Antarctic krill, fish, cephalopods, marine mammals, seabirds, and benthos. The general prognosis for ASO marine habitats is for an overall warming and freshening, strengthening of westerly winds, with a potential pole-ward movement of those winds and the frontal systems, and an increase in ocean eddy activity. Many habitat parameters will have regionally specific changes, particularly relating to sea ice characteristics and seasonal dynamics. Lower trophic levels are expected to move south as the ocean conditions in which they are currently found move pole-ward. For Antarctic krill and finfish, the latitudinal breadth of their range will depend on their tolerance of warming oceans and changes to productivity. Ocean acidification is a concern not only for calcifying organisms but also for crustaceans such as Antarctic krill; it is also likely to be the most important change in benthic habitats over the coming century. For marine mammals and birds, the expected changes primarily relate to their flexibility in moving to alternative locations for food and the energetic cost of longer or more complex foraging trips for those that are bound to breeding colonies. Few species are sufficiently well studied to make comprehensive species-specific vulnerability assessments possible. Priorities for future work are discussed.

  8. Tradeoffs between income, biodiversity, and ecosystem functioning during tropical rainforest conversion and agroforestry intensification

    PubMed Central

    Steffan-Dewenter, Ingolf; Kessler, Michael; Barkmann, Jan; Bos, Merijn M.; Buchori, Damayanti; Erasmi, Stefan; Faust, Heiko; Gerold, Gerhard; Glenk, Klaus; Gradstein, S. Robbert; Guhardja, Edi; Harteveld, Marieke; Hertel, Dietrich; Höhn, Patrick; Kappas, Martin; Köhler, Stefan; Leuschner, Christoph; Maertens, Miet; Marggraf, Rainer; Migge-Kleian, Sonja; Mogea, Johanis; Pitopang, Ramadhaniel; Schaefer, Matthias; Schwarze, Stefan; Sporn, Simone G.; Steingrebe, Andrea; Tjitrosoedirdjo, Sri S.; Tjitrosoemito, Soekisman; Twele, André; Weber, Robert; Woltmann, Lars; Zeller, Manfred; Tscharntke, Teja

    2007-01-01

    Losses of biodiversity and ecosystem functioning due to rainforest destruction and agricultural intensification are prime concerns for science and society alike. Potentially, ecosystems show nonlinear responses to land-use intensification that would open management options with limited ecological losses but satisfying economic gains. However, multidisciplinary studies to quantify ecological losses and socioeconomic tradeoffs under different management options are rare. Here, we evaluate opposing land use strategies in cacao agroforestry in Sulawesi, Indonesia, by using data on species richness of nine plant and animal taxa, six related ecosystem functions, and on socioeconomic drivers of agroforestry expansion. Expansion of cacao cultivation by 230% in the last two decades was triggered not only by economic market mechanisms, but also by rarely considered cultural factors. Transformation from near-primary forest to agroforestry had little effect on overall species richness, but reduced plant biomass and carbon storage by ≈75% and species richness of forest-using species by ≈60%. In contrast, increased land use intensity in cacao agroforestry, coupled with a reduction in shade tree cover from 80% to 40%, caused only minor quantitative changes in biodiversity and maintained high levels of ecosystem functioning while doubling farmers' net income. However, unshaded systems further increased income by ≈40%, implying that current economic incentives and cultural preferences for new intensification practices put shaded systems at risk. We conclude that low-shade agroforestry provides the best available compromise between economic forces and ecological needs. Certification schemes for shade-grown crops may provide a market-based mechanism to slow down current intensification trends. PMID:17360392

  9. Tradeoffs between income, biodiversity, and ecosystem functioning during tropical rainforest conversion and agroforestry intensification.

    PubMed

    Steffan-Dewenter, Ingolf; Kessler, Michael; Barkmann, Jan; Bos, Merijn M; Buchori, Damayanti; Erasmi, Stefan; Faust, Heiko; Gerold, Gerhard; Glenk, Klaus; Gradstein, S Robbert; Guhardja, Edi; Harteveld, Marieke; Hertel, Dietrich; Höhn, Patrick; Kappas, Martin; Köhler, Stefan; Leuschner, Christoph; Maertens, Miet; Marggraf, Rainer; Migge-Kleian, Sonja; Mogea, Johanis; Pitopang, Ramadhaniel; Schaefer, Matthias; Schwarze, Stefan; Sporn, Simone G; Steingrebe, Andrea; Tjitrosoedirdjo, Sri S; Tjitrosoemito, Soekisman; Twele, André; Weber, Robert; Woltmann, Lars; Zeller, Manfred; Tscharntke, Teja

    2007-03-20

    Losses of biodiversity and ecosystem functioning due to rainforest destruction and agricultural intensification are prime concerns for science and society alike. Potentially, ecosystems show nonlinear responses to land-use intensification that would open management options with limited ecological losses but satisfying economic gains. However, multidisciplinary studies to quantify ecological losses and socioeconomic tradeoffs under different management options are rare. Here, we evaluate opposing land use strategies in cacao agroforestry in Sulawesi, Indonesia, by using data on species richness of nine plant and animal taxa, six related ecosystem functions, and on socioeconomic drivers of agroforestry expansion. Expansion of cacao cultivation by 230% in the last two decades was triggered not only by economic market mechanisms, but also by rarely considered cultural factors. Transformation from near-primary forest to agroforestry had little effect on overall species richness, but reduced plant biomass and carbon storage by approximately 75% and species richness of forest-using species by approximately 60%. In contrast, increased land use intensity in cacao agroforestry, coupled with a reduction in shade tree cover from 80% to 40%, caused only minor quantitative changes in biodiversity and maintained high levels of ecosystem functioning while doubling farmers' net income. However, unshaded systems further increased income by approximately 40%, implying that current economic incentives and cultural preferences for new intensification practices put shaded systems at risk. We conclude that low-shade agroforestry provides the best available compromise between economic forces and ecological needs. Certification schemes for shade-grown crops may provide a market-based mechanism to slow down current intensification trends.

  10. Functional group biodiversity in Eastern Boundary Upwelling Ecosystems questions the wasp-waist trophic structure

    NASA Astrophysics Data System (ADS)

    Fréon, Pierre; Arístegui, Javier; Bertrand, Arnaud; Crawford, Robert J. M.; Field, John C.; Gibbons, Mark J.; Tam, Jorge; Hutchings, Larry; Masski, Hicham; Mullon, Christian; Ramdani, Mohamed; Seret, Bernard; Simier, Monique

    2009-12-01

    The species diversity of the four major Eastern Boundary Upwelling Ecosystems (EBUEs) is studied and compared with the aim of better understanding their functioning. Functional groups (FGs) of organisms were defined according to their taxonomy, body size and trophic level (TL), and span from plankton to top predators. Four large sub-divisions are defined in each system: two latitudinal sub-divisions (north and south) and two zonal sub-divisions (inshore and offshore), resulting in four sub-ecosystems per EBUE. A semi-quantitative approach is used in which only the dominant species (contributing 90% of overall biomass) are considered. EBUEs are compared in regard to their species composition, dominant species richness and evenness within FGs. The data are interpreted, focusing on latitudinal, zonal and depth gradients of diversity. Trophic flows (inflow and outflow) through the small pelagic fish FG are derived from different Ecopath models. This analysis of the four ecosystems and their sub-divisions does not provide support for the expected wasp-waist food web structure and functioning, with a single or several species of small pelagic fish primarily channelling the energy flow from lower to higher TL. Instead, similar low levels of richness were observed in many FGs of intermediate TL, allowing several energy transfer pathways. The gamma diversity is high due to the geographical distance between EBUEs and the presence or absence of rivers, but not to differences in their latitudinal position. The beta diversity is also high, due to the same factors plus the variation in shelf width and the contrast between inshore and offshore sub-divisions. The differences in richness and evenness among EBUEs are minor and do not explain the higher secondary and tertiary productivity of the Humboldt ecosystem.

  11. Cognitive function in the affective disorders: a prospective study.

    PubMed

    Bulbena, A; Berrios, G E

    1993-01-01

    A prospective, controlled study of 50 subjects confirmed claims that major depression or mania may cause temporary disorders of attention, memory, visuo-spatial function, and choice reaction time, and cause-independently of medication-the appearance of glabellar tap, positive hand-face test, nuchocephalic reflex, and graphesthesia. On follow-up, all these phenomena either disappeared or markedly improved. Age and age of onset, but not pre-morbid intelligence or history of ECT, seemed to modulate the severity of the cognitive impairment. Presence of delusions predicted poor (but reversible) visuo-spatial function. Cognitive impairment accompanied by reversible soft neurological signs was more marked but patients thus affected surprisingly showed lower depressive scores; this was interpreted as representing a secondary, 'organic' form of affective disorder (i.e. a behavioural phenocopy of depression) characterised by a reduced capacity to experience depressive symptoms and by little improvement at follow-up.

  12. Shifts in plant functional types have time-dependent and regionally variable impacts on dryland ecosystem water balance

    USGS Publications Warehouse

    Bradford, John B.; Schlaepfer, Daniel R.; Lauenroth, William K.; Burke, Ingrid C.

    2014-01-01

    5. Synthesis. This study provides a novel, regional-scale assessment of how plant functional type transitions may impact ecosystem water balance in sagebrush-dominated ecosystems of North America. Results illustrate that the ecohydrological consequences of changing vegetation depend strongly on climate and suggest that decreasing woody plant abundance may have only limited impact on evapotranspiration and water yield.

  13. Field observed relationships between biodiversity and ecosystem functioning during secondary succession in a tropical lowland rainforest

    NASA Astrophysics Data System (ADS)

    Bu, Wensheng; Zang, Runguo; Ding, Yi

    2014-02-01

    The relationship between biodiversity and ecosystem functioning (BEF) is one of the most concerned topics in ecology. However, most of the studies have been conducted in controlled experiments in grasslands, few observational field studies have been carried out in forests. In this paper, we report variations of species diversity, functional diversity and aboveground biomass (AGB) for woody plants (trees and shrubs) along a chronosequence of four successional stages (18-year-old fallow, 30-year-old fallow, 60-year-old fallow, and old-growth forest) in a tropical lowland rainforest recovered after shifting cultivation on Hainan Island, China. Fifty randomly selected sample plots of 20 m × 20 m were investigated in each of the four successional stages. Four functional traits (specific leaf area, wood density, maximum species height and leaf dry matter content) were measured for each woody plants species and the relationships between species/functional diversity and AGB during secondary succession were explored. The results showed that both plant diversity and AGB recovered gradually with the secondary succession. AGB was positively correlated with both species and functional diversity in each stage of succession. Consistent with many controlled experimental results in grasslands, our observational field study confirms that ecosystem functioning is closely related to biodiversity during secondary succession in species rich tropical forests.

  14. The resilience and functional role of moss in boreal and arctic ecosystems

    USGS Publications Warehouse

    Turetsky, M.; Bond-Lamberty, B.; Euskirchen, E.S.; Talbot, J. J.; Frolking, S.; McGuire, A.D.; Tuittila, E.S.

    2012-01-01

    Mosses in northern ecosystems are ubiquitous components of plant communities, and strongly influence nutrient, carbon and water cycling. We use literature review, synthesis and model simulations to explore the role of mosses in ecological stability and resilience. Moss community responses to disturbance showed all possible responses (increases, decreases, no change) within most disturbance categories. Simulations from two process-based models suggest that northern ecosystems would need to experience extreme perturbation before mosses were eliminated. But simulations with two other models suggest that loss of moss will reduce soil carbon accumulation primarily by influencing decomposition rates and soil nitrogen availability. It seems clear that mosses need to be incorporated into models as one or more plant functional types, but more empirical work is needed to determine how to best aggregate species. We highlight several issues that have not been adequately explored in moss communities, such as functional redundancy and singularity, relationships between response and effect traits, and parameter vs conceptual uncertainty in models. Mosses play an important role in several ecosystem processes that play out over centuries – permafrost formation and thaw, peat accumulation, development of microtopography – and there is a need for studies that increase our understanding of slow, long-term dynamical processes.

  15. The resilience and functional role of moss in boreal and arctic ecosystems.

    PubMed

    Turetsky, M R; Bond-Lamberty, B; Euskirchen, E; Talbot, J; Frolking, S; McGuire, A D; Tuittila, E-S

    2012-10-01

    Mosses in northern ecosystems are ubiquitous components of plant communities, and strongly influence nutrient, carbon and water cycling. We use literature review, synthesis and model simulations to explore the role of mosses in ecological stability and resilience. Moss community responses to disturbance showed all possible responses (increases, decreases, no change) within most disturbance categories. Simulations from two process-based models suggest that northern ecosystems would need to experience extreme perturbation before mosses were eliminated. But simulations with two other models suggest that loss of moss will reduce soil carbon accumulation primarily by influencing decomposition rates and soil nitrogen availability. It seems clear that mosses need to be incorporated into models as one or more plant functional types, but more empirical work is needed to determine how to best aggregate species. We highlight several issues that have not been adequately explored in moss communities, such as functional redundancy and singularity, relationships between response and effect traits, and parameter vs conceptual uncertainty in models. Mosses play an important role in several ecosystem processes that play out over centuries - permafrost formation and thaw, peat accumulation, development of microtopography - and there is a need for studies that increase our understanding of slow, long-term dynamical processes. PMID:22924403

  16. Impacts of discarded plastic bags on marine assemblages and ecosystem functioning.

    PubMed

    Green, Dannielle Senga; Boots, Bas; Blockley, David James; Rocha, Carlos; Thompson, Richard

    2015-05-01

    The accumulation of plastic debris is a global environmental problem due to its durability, persistence, and abundance. Although effects of plastic debris on individual marine organisms, particularly mammals and birds, have been extensively documented (e.g., entanglement and choking), very little is known about effects on assemblages and consequences for ecosystem functioning. In Europe, around 40% of the plastic items produced are utilized as single-use packaging, which rapidly accumulate in waste management facilities and as litter in the environment. A range of biodegradable plastics have been developed with the aspiration of reducing the persistence of litter; however, their impacts on marine assemblages or ecosystem functioning have never been evaluated. A field experiment was conducted to assess the impact of conventional and biodegradable plastic carrier bags as litter on benthic macro- and meio-faunal assemblages and biogeochemical processes (primary productivity, redox condition, organic matter content, and pore-water nutrients) on an intertidal shore near Dublin, Ireland. After 9 weeks, the presence of either type of bag created anoxic conditions within the sediment along with reduced primary productivity and organic matter and significantly lower abundances of infaunal invertebrates. This indicates that both conventional and biodegradable bags can rapidly alter marine assemblages and the ecosystem services they provide. PMID:25822754

  17. Effects of macrophyte species richness on wetland ecosystem functioning and services.

    PubMed

    Engelhardt, K A; Ritchie, M E

    2001-06-01

    Wetlands provide many important ecosystem services to human society, which may depend on how plant diversity influences biomass production and nutrient retention. Vascular aquatic plant diversity may not necessarily enhance wetland ecosystem functioning, however, because competition among these plant species can be strong, often resulting in the local dominance of a single species. Here we have manipulated the species richness of rooted, submerged aquatic plant (macrophyte) communities in experimental wetland mesocosms. We found higher algal and total plant (algal plus macrophyte) biomass, as well as lower loss of total phosphorus, in mesocosms with a greater richness of macrophyte species. Greater plant biomass resulted from a sampling effect; that is, the increased chance in species mixtures that algal production would be facilitated by the presence of a less competitive species-in this case, crisped pondweed. Lower losses of total phosphorus resulted from the greater chance in species mixtures of a high algal biomass and the presence of sago pondweed, which physically filter particulate phosphorus from the water. These indirect and direct effects of macrophyte species richness on algal production, total plant biomass and phosphorus loss suggest that management practices that maintain macrophyte diversity may enhance the functioning and associated services of wetland ecosystems.

  18. Impacts of discarded plastic bags on marine assemblages and ecosystem functioning.

    PubMed

    Green, Dannielle Senga; Boots, Bas; Blockley, David James; Rocha, Carlos; Thompson, Richard

    2015-05-01

    The accumulation of plastic debris is a global environmental problem due to its durability, persistence, and abundance. Although effects of plastic debris on individual marine organisms, particularly mammals and birds, have been extensively documented (e.g., entanglement and choking), very little is known about effects on assemblages and consequences for ecosystem functioning. In Europe, around 40% of the plastic items produced are utilized as single-use packaging, which rapidly accumulate in waste management facilities and as litter in the environment. A range of biodegradable plastics have been developed with the aspiration of reducing the persistence of litter; however, their impacts on marine assemblages or ecosystem functioning have never been evaluated. A field experiment was conducted to assess the impact of conventional and biodegradable plastic carrier bags as litter on benthic macro- and meio-faunal assemblages and biogeochemical processes (primary productivity, redox condition, organic matter content, and pore-water nutrients) on an intertidal shore near Dublin, Ireland. After 9 weeks, the presence of either type of bag created anoxic conditions within the sediment along with reduced primary productivity and organic matter and significantly lower abundances of infaunal invertebrates. This indicates that both conventional and biodegradable bags can rapidly alter marine assemblages and the ecosystem services they provide.

  19. Testing the field of dreams hypothesis: functional responses to urbanization and restoration in stream ecosystems.

    PubMed

    Sudduth, Elizabeth B; Hassett, Brooke A; Cada, Peter; Bernhardt, Emily S

    2011-09-01

    As catchments become increasingly urban, the streams that drain them become increasingly degraded. Urban streams are typically characterized by high-magnitude storm flows, homogeneous habitats, disconnected riparian zones, and elevated nitrogen concentrations. To reverse the degradation of urban water quality, watershed managers and regulators are increasingly turning to stream restoration approaches. By reshaping the channel and reconnecting the surface waters with their riparian zone, practitioners intend to enhance the natural nutrient retention capacity of the restored stream ecosystem. Despite the exponential growth in stream restoration projects and expenditures, there has been no evaluation to date of the efficacy of urban stream restoration projects in enhancing nitrogen retention or in altering the underlying ecosystem metabolism that controls instream nitrogen consumption. In this study, we compared ecosystem metabolism and nitrate uptake kinetics in four stream restoration projects within urban watersheds to ecosystem functions measured in four unrestored urban stream segments and four streams draining minimally impacted forested watersheds in central North Carolina, U.S.A. All 12 sites were surveyed in June through August of 2006 and again in January through March of 2007. We anticipated that urban streams would have enhanced rates of ecosystem metabolism and nitrate uptake relative to forested streams due to the increases in nutrient loads and temperature associated with urbanization, and we predicted that restored streams would have further enhanced rates for these ecosystem functions by virtue of their increased habitat heterogeneity and water residence times. Contrary to our predictions we found that stream metabolism did not differ between stream types in either season and that nitrate uptake kinetics were not different between stream types in the winter. During the summer, restored stream reaches had substantially higher rates of nitrate uptake

  20. Land use/ land cover and ecosystem functions change in the grassland restoration program areas in China from 2000 to 2010

    NASA Astrophysics Data System (ADS)

    Zhang, H.; Fan, J.

    2015-12-01

    The grassland restoration areas in China, most of which was located in arid and semi-arid areas, are affected by climate change and anthropogenic activities. Using the 3S (RS, GIS, GPS) technologies, quantitative analysis method of landscape patterns and ecological simulation, this study examines the spatiotemporal characteristics of land use/ land cover and ecosystem functions change in the grassland restoration areas in China from 2000 to 2010. We apply two parameters land use transfer matrix and land use dynamic degree to explore the speed and regional differentiation of land use change. We propose vegetation coverage, net primary production (NPP), soil and water conservation capacity to assess the ecosystem functions. This study analyzes the characteristics of landscape patterns at the class and landscape levels and explores the ecological effect of land use pattern and regional ecological processes. The results show that: (1) Grassland and others were the main landscape types in the study area in the past decade. The ecosystem structure was stable. About 0.37% of the total grassland area in 2000 experienced change in land use / land cover types. The area of woodlands, wetlands, farmlands, and built-up areas expanded. The area of others has declined. (2) The dynamic degree of regional land use was less than one percent in the recent ten years. The speed of land use and land cover change was low, and regional differentiation of change between the provinces was small. (3) The matrix of the landscape did not change in the study area. Landscape fragmentation index values decreased progressively; landscape diversity rose continuously; landscape aggregation and continuity decreased slightly; the landscape maintained relative integrity. (4) Ecosystem functions has increased as a whole. The vegetation coverages with significant increase (with a 1.99% yr-1 slope of regression) in the total study area; NPP has a fluctuating and increasing tendency, ranging from 218.23 g

  1. The magnitude of lost ecosystem structure and function in urban streams and the effectiveness of watershed-based management (Invited)

    NASA Astrophysics Data System (ADS)

    Smucker, N. J.; Detenbeck, N. E.; Kuhn, A.

    2013-12-01

    compared to streams with developed watersheds and no management practices in place. However, ecosystem measures at restored sites were still only 53% of those in minimally disturbed reference streams. Some of our ongoing work further examines how watershed development and riparian condition affect stream ecosystem functions by altering the sources and delivery of nutrients and carbon. Our results can help inform management priorities and expectations, and they emphasize the importance of implementing mindful development and protective actions in a watershed context, especially in watersheds near impervious cover thresholds. Continued research on linked terrestrial-aquatic systems, improved BMP tracking, and ongoing monitoring will be essential to conserving and restoring the mechanisms that sustain valued ecological attributes and ecosystem services of streams.

  2. Potential impacts of climate change on biogeochemical functioning of Cerrado ecosystems.

    PubMed

    Bustamante, M M C; Nardoto, G B; Pinto, A S; Resende, J C F; Takahashi, F S C; Vieira, L C G

    2012-08-01

    The Cerrado Domain comprises one of the most diverse savannas in the world and is undergoing a rapid loss of habitats due to changes in fire regimes and intense conversion of native areas to agriculture. We reviewed data on the biogeochemical functioning of Cerrado ecosystems and evaluated the potential impacts of regional climate changes. Variation in temperature extremes and in total amount of rainfall and altitude throughout the Cerrado determines marked differences in the composition of species. Cerrado ecosystems are controlled by interactions between water and nutrient availability. In general, nutrient cycles (N, P and base cations) are very conservative, while litter, microbial and plant biomass are important stocks. In terms of C cycling, root systems and especially the soil organic matter are the most important stocks. Typical cerrado ecosystems function as C sinks on an annual basis, although they work as source of C to the atmosphere close to the end of the dry season. Fire is an important factor altering stocks and fluxes of C and nutrients. Predicted changes in temperature, amount and distribution of precipitation vary according to Cerrado sub-regions with more marked changes in the northeastern part of the domain. Higher temperatures, decreases in rainfall with increase in length of the dry season could shift net ecosystem exchanges from C sink to source of C and might intensify burning, reducing nutrient stocks. Interactions between the heterogeneity in the composition and abundance of biological communities throughout the Cerrado Domain and current and future changes in land use make it difficult to project the impacts of future climate scenarios at different temporal and spatial scales and new modeling approaches are needed.

  3. Recent advances in exploring physiology and biodiversity of ectomycorrhizas highlight the functioning of these symbioses in ecosystems.

    PubMed

    Buscot, F; Munch, J C; Charcosset, J Y; Gardes, M; Nehls, U; Hampp, R

    2000-12-01

    Ectomycorrhizas, the dominating mycorrhizal symbiosis in boreal, temperate and some tropical forests, are formed by 5000-6000 species of the asco- and basidiomycetes. This high diversity of fungal partners allows optimal foraging and mobilisation of various nitrogen and phosphorus forms from organic soil layers. In this review, two approaches to study the functioning of this multitude of symbiotic associations are presented. On selected culture models, physiological and molecular investigations have shown that the supply of hexoses has a key function in controlling the plant-fungus interaction via partner-specific regulation of gene expression. Environmental factors which affect fungal carbon supply, such as increased nitrogen availability, also affect mycorrhiza formation. Based on such laboratory results, the adaptative capability of ectomycorrhizas to changing field conditions is discussed. The second approach consists of analysing the distribution of mycorrhizas in ecosystem compartments and to relate distribution patterns to variations of ecological factors. Recent advances in identification of fungal partners in ectomycorrhizas by analysing the internal transcribed spacer of ribosomal DNA are presented, which can help to resolve sampling problems in field studies. The limits of the laboratory and the field approaches are discussed. Despite some problems, this combined approach is the most promising. Direct investigation of gene expression, which has been introduced for soil bacteria, will be difficult in the case of mycorrhizal fungi which constitute organisms with functionally varying structures. PMID:11077153

  4. Faunal impact on vegetation structure and ecosystem function in mangrove forests: A review

    USGS Publications Warehouse

    Cannicci, Stefano; Burrows, Damien; Fratini, Sara; Smith, Thomas J.; Offenberg, Joachim; Dahdouh-Guebas, Farid

    2008-01-01

    The last 20 years witnessed a real paradigm shift concerning the impact of biotic factors on ecosystem functions as well as on vegetation structure of mangrove forests. Before this small scientific revolution took place, structural aspects of mangrove forests were viewed to be the result of abiotic processes acting from the bottom-up, while, at ecosystem level, the outwelling hypothesis stated that mangroves primary production was removed via tidal action and carried to adjacent nearshore ecosystems where it fuelled detrital based food-webs. The sesarmid crabs were the first macrofaunal taxon to be considered a main actor in mangrove structuring processes, thanks to a number of studies carried out in the Indo-Pacific forests in the late 1970s and early 1980s. Following these classical papers, a number of studies on Sesarmidae feeding and burrowing ecology were carried out, which leave no doubts about the great importance of these herbivorous crabs in structuring and functioning Old world ecosystems. Although Sesarmidae are still considered very important in shaping mangrove structure and functioning, recent literature emphasizes the significance of other invertebrates. The Ocypodidae have now been shown to have the same role as Sesarmidae in terms of retention of forest products and organic matter processing in New world mangroves. In both New and Old world mangroves, crabs process large amounts of algal primary production, contribute consistently to retention of mangrove production and as ecosystem engineers, change particle size distribution and enhance soil aeration. Our understanding of the strong impact of gastropods, by means of high intake rates of mangrove products and differential consumption of propagules, has changed only recently. The role of insects must also be stressed. It is now clear that older techniques used to assess herbivory rates by insects strongly underestimate their impact, both in case of leaf eating and wood boring species and that

  5. Bridging structure and function in semi-arid ecosystems by integrating remote sensing and ground based measurements

    NASA Astrophysics Data System (ADS)

    Krofcheck, Dan J.

    The Southwestern US is projected to continue to experience a significant warming trend, with increased variability in the timing and magnitude of rainfall events. The effects of theses changes in climate are already manifesting in the form of expansive, prolonged 'megadroughts', which have resulted in the widespread mortality of woody vegetation across the region.Therefore the need to monitor and model forest mortality and carbon dynamics at the landscape and regional scale is an essential component of regional and global climate mitigation strategies, and critical if we are to understand how the imminent state transitions taking place in forests globally will affect climate forcing and feedbacks. Remote sensing offers the only solution to multitemporal regional observation, yet many challenges exist with employing modern remote sensing solutions in highly stressed vegetation characteristic of semi-arid biomes, making one of the most expansive biomes on the globe also one of the most difficult to accurately monitor and model. The goal of this research was to investigate how changes in the structure of semi-arid woodlands following forest mortality impacts ecosystem function, and address this question in the context of remote sensing data sets, thereby contributing to the remote sensing community's ability to interact with these challenging ecosystems. We first focused on pinus edulis and juniperous monosperma (pinon-juniper) woodlands, as they comprise a model semi-arid biome. We tested the ability of high resolution remote sensing data to mechanistically describe the patterns in overstory mortality and understory green-up, and were able to observe the heterogeneous response of the understory as a function of cover type. We also investigated the relationship between changes in soil water content and the greenness of the canopy, noting that in these stress ecosystems there is often a decoupling of the canopy as measured remotely (e.g., via vegetation indices, VI

  6. Ecosystem function in waste stabilisation ponds: Improving water quality through a better understanding of biophysical coupling

    NASA Astrophysics Data System (ADS)

    Ghadouani, Anas; Reichwaldt, Elke S.; Coggins, Liah X.; Ivey, Gregory N.; Ghisalberti, Marco; Zhou, Wenxu; Laurion, Isabelle; Chua, Andrew

    2014-05-01

    Wastewater stabilisation ponds (WSPs) are highly productive systems designed to treat wastewater using only natural biological and chemical processes. Phytoplankton, microbial communities and hydraulics play important roles for ecosystem functionality of these pond systems. Although WSPs have been used for many decades, they are still considered as 'black box' systems as very little is known about the fundamental ecological processes which occur within them. However, a better understanding of how these highly productive ecosystems function is particularly important for hydrological processes, as treated wastewater is commonly discharged into streams, rivers, and oceans, and subject to strict water quality guidelines. WSPs are known to operate at different levels of efficiency, and treatment efficiency of WSPs is dependent on physical (flow characteristics and sludge accumulation and distribution) and biological (microbial and phytoplankton communities) characteristics. Thus, it is important to gain a better understanding of the role and influence of pond hydraulics and vital microbial communities on pond performance and WSP functional stability. The main aim of this study is to investigate the processes leading to differences in treatment performance of WSPs. This study uses a novel and innovative approach to understand these factors by combining flow cytometry and metabolomics to investigate various biochemical characteristics, including the metabolite composition and microbial community within WSPs. The results of these analyses will then be combined with results from the characterisation of pond hydrodynamics and hydraulic performance, which will be performed using advanced hydrodynamic modelling and advanced sludge profiling technology. By understanding how hydrodynamic and biological processes influence each other and ecosystem function and stability in WSPs, we will be able to propose ways to improve the quality of the treatment using natural processes, with

  7. Do differences in food web structure between organic and conventional farms affect the ecosystem service of pest control?

    PubMed

    Macfadyen, Sarina; Gibson, Rachel; Polaszek, Andrew; Morris, Rebecca J; Craze, Paul G; Planqué, Robert; Symondson, William O C; Memmott, Jane

    2009-03-01

    While many studies have demonstrated that organic farms support greater levels of biodiversity, it is not known whether this translates into better provision of ecosystem services. Here we use a food-web approach to analyse the community structure and function at the whole-farm scale. Quantitative food webs from 10 replicate pairs of organic and conventional farms showed that organic farms have significantly more species at three trophic levels (plant, herbivore and parasitoid) and significantly different network structure. Herbivores on organic farms were attacked by more parasitoid species on organic farms than on conventional farms. However, differences in network structure did not translate into differences in robustness to simulated species loss and we found no difference in percentage parasitism (natural pest control) across a variety of host species. Furthermore, a manipulative field experiment demonstrated that the higher species richness of parasitoids on the organic farms did not increase mortality of a novel herbivore used to bioassay ecosystem service. The explanation for these differences is likely to include inherent differences in management strategies and landscape structure between the two farming systems.

  8. Critical indirect effects of climate change on sub-Antarctic ecosystem functioning

    PubMed Central

    Louise Allan, E; William Froneman, P; Durgadoo, Jonathan V; McQuaid, Christopher D; Ansorge, Isabelle J; Richoux, Nicole B

    2013-01-01

    Sub-Antarctic islands represent critical breeding habitats for land-based top predators that dominate Southern Ocean food webs. Reproduction and molting incur high energetic demands that are sustained at the sub-Antarctic Prince Edward Islands (PEIs) by both inshore (phytoplankton blooms; “island mass effect”; autochthonous) and offshore (allochthonous) productivity. As the relative contributions of these sustenance pathways are, in turn, affected by oceanographic conditions around the PEIs, we address the consequences of climatically driven changes in the physical environment on this island ecosystem. We show that there has been a measurable long-term shift in the carbon isotope signatures of the benthos inhabiting the shallow shelf region of the PEIs, most likely reflecting a long-term decline in enhanced phytoplankton productivity at the islands in response to a climate-driven shift in the position of the sub-Antarctic Front. Our results indicate that regional climate change has affected the balance between allochthonous and autochthonous productivity at the PEIs. Over the last three decades, inshore-feeding top predators at the islands have shown a marked decrease in their population sizes. Conversely, population sizes of offshore-feeding predators that forage over great distances from the islands have remained stable or increased, with one exception. Population decline of predators that rely heavily on organisms inhabiting the inshore region strongly suggest changes in prey availability, which are likely driven by factors such as fisheries impacts on some prey populations and shifts in competitive interactions among predators. In addition to these local factors, our analysis indicates that changes in prey availability may also result indirectly through regional climate change effects on the islands' marine ecosystem. Most importantly, our results indicate that a fundamental shift in the balance between allochthonous and autochthonous trophic pathways

  9. Species interactions regulate the collapse of biodiversity and ecosystem function in tropical forest fragments.

    PubMed

    Bregman, Tom P; Lees, Alexander C; Seddon, Nathalie; Macgregor, Hannah E A; Darski, Bianca; Aleixo, Alexandre; Bonsall, Michael B; Tobias, Joseph A

    2015-10-01

    Competitive interactions among species with similar ecological niches are known to regulate the assembly of biological communities. However, it is not clear whether such forms of competition can predict the collapse of communities and associated shifts in ecosystem function in the face of environmental change. Here, we use phylogenetic and functional trait data to test whether communities of two ecologically important guilds of tropical birds (frugivores and insectivores) are structured by species interactions in a fragmented Amazonian forest landscape. In both guilds, we found that forest patch size, quality, and degree of isolation influence the phylogenetic and functional trait structure of communities, with small, degraded, or isolated forest patches having an increased signature of competition (i.e., phylogenetic and functional trait overdispersion in relation to null models). These results suggest that local extinctions in the context of fragmentation are nonrandom, with a consistent bias toward more densely occupied regions of niche space. We conclude that the loss of biodiversity in fragmented landscapes is mediated by niche-based competitive interactions among species, with potentially far-reaching implications for key ecosystem processes, including seed dispersal and plant damage by phytophagous insects. PMID:26649390

  10. Species interactions regulate the collapse of biodiversity and ecosystem function in tropical forest fragments.

    PubMed

    Bregman, Tom P; Lees, Alexander C; Seddon, Nathalie; Macgregor, Hannah E A; Darski, Bianca; Aleixo, Alexandre; Bonsall, Michael B; Tobias, Joseph A

    2015-10-01

    Competitive interactions among species with similar ecological niches are known to regulate the assembly of biological communities. However, it is not clear whether such forms of competition can predict the collapse of communities and associated shifts in ecosystem function in the face of environmental change. Here, we use phylogenetic and functional trait data to test whether communities of two ecologically important guilds of tropical birds (frugivores and insectivores) are structured by species interactions in a fragmented Amazonian forest landscape. In both guilds, we found that forest patch size, quality, and degree of isolation influence the phylogenetic and functional trait structure of communities, with small, degraded, or isolated forest patches having an increased signature of competition (i.e., phylogenetic and functional trait overdispersion in relation to null models). These results suggest that local extinctions in the context of fragmentation are nonrandom, with a consistent bias toward more densely occupied regions of niche space. We conclude that the loss of biodiversity in fragmented landscapes is mediated by niche-based competitive interactions among species, with potentially far-reaching implications for key ecosystem processes, including seed dispersal and plant damage by phytophagous insects.

  11. Net ecosystem production in a Little Ice Age moraine: the role of plant functional traits

    NASA Astrophysics Data System (ADS)

    Varolo, E.; Zanotelli, D.; Tagliavini, M.; Zerbe, S.; Montagnani, L.

    2015-07-01

    the carbon cycle. Therefore, to analyze NEE of any glacier forefield ecosystem, different functional traits of the vegetation communities must be taken into consideration. Moreover, to assess the net ecosystem carbon balance it is necessary to consider the lateral fluxes of carbon via animal consumption, winter respiration, and in a broader temporal perspective, the different stages characterizing the primary succession.

  12. Factors affecting sexual function in menopause: A review article.

    PubMed

    Nazarpour, Soheila; Simbar, Masoumeh; Tehrani, Fahimeh Ramezani

    2016-08-01

    This study aimed to systematically review the articles on factors affecting sexual function during menopause. Searching articles indexed in Pubmed, Science Direct, Iranmedex, EMBASE, Scopus, and Scientific Information Database databases, a total number of 42 studies published between 2003 and 2013 were selected. Age, estrogen deficiency, type of menopause, chronic medical problems, partner's sex problems, severity of menopause symptoms, dystocia history, and health status were the physical factors influencing sexual function of menopausal women. There were conflicting results regarding the amount of androgens, hormonal therapy, exercise/physical activity, and obstetric history. In the mental-emotional area, all studies confirmed the impact of depression and anxiety. Social factors, including smoking, alcohol consumption, the quality of relationship with husband, partner's loyalty, sexual knowledge, access to health care, a history of divorce or the death of a husband, living apart from a spouse, and a negative understanding of women's health were found to affect sexual function; however, there were conflicting results regarding the effects of education, occupation, socioeconomic status, marital duration, and frequency of sexual intercourse. PMID:27590367

  13. Impacts of multiple stressors on ecosystem function: Leaf decomposition in constructed urban wetlands.

    PubMed

    Mackintosh, Teresa J; Davis, Jenny A; Thompson, Ross M

    2016-01-01

    The impact of stormwater on stream biota is well documented, but less is known about the impacts on ecosystem processes, such as the breakdown of organic matter. This study sought to establish whether the degree of urbanisation affected rates of leaf-litter breakdown within constructed wetlands. A litter bag method was used to ascertain rate of decomposition along a gradient of urbanisation (total imperviousness, TI), in constructed wetlands in western and south-eastern Melbourne. A significant positive relationship between TI and breakdown rate was found in the south-eastern wetlands. The significant reduction in rate of invertebrate-mediated breakdown with increasing concentration of certain metals was consistent with other studies. However, overall there was an increase in rate of breakdown. Studies have shown that the effects of heavy metals can be negated if nutrient levels are high. Our results suggest that other parameters besides exposure to contaminants are likely to affect leaf litter breakdown.

  14. Impacts of multiple stressors on ecosystem function: Leaf decomposition in constructed urban wetlands.

    PubMed

    Mackintosh, Teresa J; Davis, Jenny A; Thompson, Ross M

    2016-01-01

    The impact of stormwater on stream biota is well documented, but less is known about the impacts on ecosystem processes, such as the breakdown of organic matter. This study sought to establish whether the degree of urbanisation affected rates of leaf-litter breakdown within constructed wetlands. A litter bag method was used to ascertain rate of decomposition along a gradient of urbanisation (total imperviousness, TI), in constructed wetlands in western and south-eastern Melbourne. A significant positive relationship between TI and breakdown rate was found in the south-eastern wetlands. The significant reduction in rate of invertebrate-mediated breakdown with increasing concent