Data from: A standardized assessment of forest mammal communities reveals consistent functional composition and vulnerability across the tropics
Rovero, Francesco ; Ahumada, Jorge ; Jansen, Patrick ; Sheil, Douglas ; Alvarez, Patricia ; Boekee, Kelly ; Espinosa, Santiago ; Lima, Marcela Guimarães Moreira ; Martin, Emanuel H. ; O'Brien, Timothy G. ; Salvador, Julia ; Santos, Fernanda ; Rosa, Melissa ; Sutherland, Chris ; Tenan, Simone - \ 2019
University of Florence
community structure - conservation - functional traits - mammals - trophic guild - tropical forest - camera traps
Understanding global diversity patterns has benefitted from a focus on functional traits and how they relate to variation in environmental conditions among assemblages. Distant communities in similar environments often share characteristics, and for tropical forest mammals, this functional trait convergence has been demonstrated at coarse scales (110-200 km resolution), but less is known about how these patterns manifest at fine scales, where local processes (e.g., habitat features and anthropogenic activities) and biotic interactions occur. Here, we used standardized camera trapping data and a novel analytical method that accounts for imperfect detection to assess how the functional composition of terrestrial mammal communities for two traits – trophic guild and body mass – varies across 16 protected areas in tropical forests and three continents, in relation to the extent of protected habitat and anthropogenic pressures. We found that despite their taxonomic differences, communities generally have a consistent trophic guild composition, and respond similarly to these factors. Insectivores were found to be sensitive to the size of protected habitat and surrounding human population density. Body mass distribution varied little among communities both in terms of central tendency and spread, and interestingly, community average body mass declined with proximity to human settlements. Results indicate predicted trait convergence among assemblages at the coarse scale reflects consistent functional composition among communities at the local scale, suggesting that broadly similar habitats and selective pressures shaped communities with similar trophic strategies and responses to drivers of change. These similarities provide a foundation for assessing assemblages under anthropogenic threats and sharing conservation measures.Understanding global diversity patterns has benefitted from a focus on functional traits and how they relate to variation in environmental conditions among assemblages. Distant communities in similar environments often share characteristics, and for tropical forest mammals, this functional trait convergence has been demonstrated at coarse scales (110-200 km resolution), but less is known about how these patterns manifest at fine scales, where local processes (e.g., habitat features and anthropogenic activities) and biotic interactions occur. Here, we used standardized camera trapping data and a novel analytical method that accounts for imperfect detection to assess how the functional composition of terrestrial mammal communities for two traits – trophic guild and body mass – varies across 16 protected areas in tropical forests and three continents, in relation to the extent of protected habitat and anthropogenic pressures. We found that despite their taxonomic differences, communities generally have a consistent trophic guild composition, and respond similarly to these factors. Insectivores were found to be sensitive to the size of protected habitat and surrounding human population density. Body mass distribution varied little among communities both in terms of central tendency and spread, and interestingly, community average body mass declined with proximity to human settlements. Results indicate predicted trait convergence among assemblages at the coarse scale reflects consistent functional composition among communities at the local scale, suggesting that broadly similar habitats and selective pressures shaped communities with similar trophic strategies and responses to drivers of change. These similarities provide a foundation for assessing assemblages under anthropogenic threats and sharing conservation measures.
Evaluating Aquatic invertebrate vulnerability to insecticides based on intrinsic sensitivuty, biological traits, and toxic mode of action
Rico, A. ; Brink, P.J. van den - \ 2015
Environmental Toxicology and Chemistry 34 (2015)8. - ISSN 0730-7268 - p. 1907 - 1917.
ecological risk-assessment - fresh-water arthropods - species sensitivity - community structure - lambda-cyhalothrin - short-term - responses - microcosms - recovery - stream
In the present study, the authors evaluated the vulnerability of aquatic invertebrates to insecticides based on their intrinsic sensitivity and their population-level recovery potential. The relative sensitivity of invertebrates to 5 different classes of insecticides was calculated at the genus, family, and order levels using the acute toxicity data available in the US Environmental Protection Agency ECOTOX database. Biological trait information was linked to the calculated relative sensitivity to evaluate correlations between traits and sensitivity and to calculate a vulnerability index, which combines intrinsic sensitivity and traits describing the recovery potential of populations partially exposed to insecticides (e.g., voltinism, flying strength, occurrence in drift). The analysis shows that the relative sensitivity of arthropods depends on the insecticide mode of action. Traits such as degree of sclerotization, size, and respiration type showed good correlation to sensitivity and can be used to make predictions for invertebrate taxa without a priori sensitivity knowledge. The vulnerability analysis revealed that some of the Ephemeroptera, Plecoptera, and Trichoptera taxa were vulnerable to all insecticide classes and indicated that particular gastropod and bivalve species were potentially vulnerable. Microcrustaceans (e.g., daphnids, copepods) showed low potential vulnerability, particularly in lentic ecosystems. The methods described in the present study can be used for the selection of focal species to be included as part of ecological scenarios and higher tier risk assessments.
Short-term impact of deep sand extraction and ecosystem-based landscaping on macrozoobenthos and sediment characteristics
Jong, M.F. de; Baptist, Martin ; Lindeboom, H.J. ; Hoekstra, P. - \ 2015
Marine Pollution Bulletin 97 (2015)1-2. - ISSN 0025-326X - p. 294 - 308.
potential environmental-impact - marine aggregate extraction - eastern english-channel - north-sea - belgian part - large-scale - community structure - gravel extraction - coastal waters - united-kingdom
We studied short-term changes in macrozoobenthos in a 20 m deep borrow pit. A boxcorer was used to sample macrobenthic infauna and a bottom sledge was used to sample macrobenthic epifauna. Sediment characteristics were determined from the boxcore samples, bed shear stress and near-bed salinity were estimated with a hydrodynamic model. Two years after the cessation of sand extraction, macrozoobenthic biomass increased fivefold in the deepest areas. Species composition changed significantly and white furrow shell (Abra alba) became abundant. Several sediment characteristics also changed significantly in the deepest parts. Macrozoobenthic species composition and biomass significantly correlated with time after cessation of sand extraction, sediment and hydrographical characteristics. Ecosystem-based landscaped sand bars were found to be effective in influencing sediment characteristics and macrozoobenthic assemblage. Significant changes in epifauna occurred in deepest parts in 2012 which coincided with the highest sedimentation rate. We recommend continuing monitoring to investigate medium and long-term impacts.
Structure and composition of the liana assemblage of a mixed rainforest in the Congo Basin
Ewango, C.E.N. ; Bongers, F. ; Makana, J.R. ; Poorter, L. ; Sosef, M.S.M. - \ 2015
Plant Ecology and Evolution 148 (2015)1. - ISSN 2032-3913 - p. 29 - 42.
barro-colorado island - tree alpha-diversity - tropical forest - silvicultural treatments - habitat associations - community structure - species-diversity - secondary forest - lowland forest - growth-rates
Background and aims – The Congo Basin lowland forest represents one of the largest tropical forest blocks in the world, but its liana assemblage has never been characterized. We evaluate liana floristics, diversity, and structure in the Ituri Forest, and determine the effects of forest structure and edaphic variation on liana species composition. Methods – Two permanent 10-ha plots (200 × 500 m), 500 m apart, were established in mixed forest. All liana individuals = 2 cm dbh were identified, measured, mapped, and marked. For 20 × 20 m subplots we distinguished terra firme and swamp, and we estimated canopy openness. Key results – The combined 20-ha area contains 15,008 lianas (dbh = 2 cm) representing 195 species, 83 genera, and 34 families. Per hectare, species number averaged 64, mean basal area was 0.71 m2 and mean Fisher's alpha, Shannon index, and Simpson diversity index values were 17.9, 3.1 and 11.4, respectively. Ten dominant plant families represented 69% of total species richness, 92% of liana abundance and 92% of basal area, while ten dominant species accounted for 63% of abundance and 59% of basal area. A single species, Manniophyton fulvum, dominated the liana community (22% of all individuals). Forty-one species (21%) had one individual only. Twiners, zoochorous, light-demanding, and meso- or microphyllous species dominated. Liana abundance increased with abundance of medium-sized and large trees but was, surprisingly, independent of small-tree abundance. Canopy openness, habitat type, and tree size were the most important factors influencing abundance and distribution of liana individuals. Conclusions – The Ituri liana assemblage stands out by showing an extreme one-species dominance. Species floristic composition is, however, generally similar to that in other tropical African forests.
Effects of large herbivores on grassland arthropod diversity
Klink, R. van; Plas, F. van der; Noordwijk, C.G.E. ; Wallis de Vries, M.F. ; Olff, H. - \ 2015
Biological Reviews 90 (2015)2. - ISSN 1464-7931 - p. 347 - 366.
ungrazed chalk grassland - ground beetle coleoptera - plant-species richness - grazing management - phytophagous insects - seminatural grasslands - community structure - tallgrass prairie - long-term - butterfly communities
Both arthropods and large grazing herbivores are important components and drivers of biodiversity in grassland ecosystems, but a synthesis of how arthropod diversity is affected by large herbivores has been largely missing. To fill this gap, we conducted a literature search, which yielded 141 studies on this topic of which 24 simultaneously investigated plant and arthropod diversity. Using the data from these 24 studies, we compared the responses of plant and arthropod diversity to an increase in grazing intensity. This quantitative assessment showed no overall significant effect of increasing grazing intensity on plant diversity, while arthropod diversity was generally negatively affected. To understand these negative effects, we explored the mechanisms by which large herbivores affect arthropod communities: direct effects, changes in vegetation structure, changes in plant community composition, changes in soil conditions, and cascading effects within the arthropod interaction web. We identify three main factors determining the effects of large herbivores on arthropod diversity: (i) unintentional predation and increased disturbance, (ii) decreases in total resource abundance for arthropods (biomass) and (iii) changes in plant diversity, vegetation structure and abiotic conditions. In general, heterogeneity in vegetation structure and abiotic conditions increases at intermediate grazing intensity, but declines at both low and high grazing intensity. We conclude that large herbivores can only increase arthropod diversity if they cause an increase in (a)biotic heterogeneity, and then only if this increase is large enough to compensate for the loss of total resource abundance and the increased mortality rate. This is expected to occur only at low herbivore densities or with spatio-temporal variation in herbivore densities. As we demonstrate that arthropod diversity is often more negatively affected by grazing than plant diversity, we strongly recommend considering the specific requirements of arthropods when applying grazing management and to include arthropods in monitoring schemes. Conservation strategies aiming at maximizing heterogeneity, including regulation of herbivore densities (through human interventions or top-down control), maintenance of different types of management in close proximity and rotational grazing regimes, are the most promising options to conserve arthropod diversity.
Intensive agriculture reduces soil biodiversity across Europe
Tsiafouli, M.A. ; Thébault, E. ; Sgardelis, S. ; Ruiter, P.C. de; Putten, W.H. van der; Birkhofer, K. ; Hemerik, L. ; Vries, F.T. de; Bardgett, R.D. ; Brady, M. ; Bjornlund, L. ; Bracht Jörgensen, H. ; Christensen, S. ; Herfelt, T. D'; Hotes, S. ; Hol, W.H.G. ; Frouz, J. ; Liiri, M. ; Mortimer, S.R. ; Setälä, H. ; Stary, J. ; Tzanopoulos, J. ; Uteseny, C. ; Wolters, V. ; Hedlund, K. - \ 2015
Global Change Biology 21 (2015)2. - ISSN 1354-1013 - p. 973 - 985.
food-web structure - land-use intensity - taxonomic distinctness - community structure - phylogenetic diversity - arthropod communities - temporal variability - 7-year period - ecosystem - management
Soil biodiversity plays a key role in regulating the processes that underpin the delivery of ecosystem goods and services in terrestrial ecosystems. Agricultural intensification is known to change the diversity of individual groups of soil biota, but less is known about how intensification affects biodiversity of the soil food web as a whole, and whether or not these effects may be generalized across regions. We examined biodiversity in soil food webs from grasslands, extensive, and intensive rotations in four agricultural regions across Europe: in Sweden, the UK, the Czech Republic and Greece. Effects of land-use intensity were quantified based on structure and diversity among functional groups in the soil food web, as well as on community-weighted mean body mass of soil fauna. We also elucidate land-use intensity effects on diversity of taxonomic units within taxonomic groups of soil fauna. We found that between regions soil food web diversity measures were variable, but that increasing land-use intensity caused highly consistent responses. In particular, land-use intensification reduced the complexity in the soil food webs, as well as the community-weighted mean body mass of soil fauna. In all regions across Europe, species richness of earthworms, Collembolans, and oribatid mites was negatively affected by increased land-use intensity. The taxonomic distinctness, which is a measure of taxonomic relatedness of species in a community that is independent of species richness, was also reduced by land-use intensification. We conclude that intensive agriculture reduces soil biodiversity, making soil food webs less diverse and composed of smaller bodied organisms. Land-use intensification results in fewer functional groups of soil biota with fewer and taxonomically more closely related species. We discuss how these changes in soil biodiversity due to land-use intensification may threaten the functioning of soil in agricultural production systems.
Growth of anaerobic methane oxidizing archaea and sulfate reducing bacteria in a high pressure membrane-capsule bioreactor
Timmers, P.H.A. ; Gieteling, J. ; Widjaja-Greefkes, H.C.A. ; Plugge, C.M. ; Stams, A.J.M. ; Lens, P.N.L. ; Meulepas, R.J.W. - \ 2015
Applied and Environmental Microbiology 81 (2015)4. - ISSN 0099-2240 - p. 1286 - 1296.
cold-seep sediments - 16s ribosomal-rna - gradient gel-electrophoresis - guaymas basin - hydrothermal sediments - microbial diversity - marine-sediments - population-dynamics - community structure - gene database
Anaerobic methane oxidizing communities of archaea (ANME) and sulfate reducing bacteria (SRB) grow slowly, which limits physiological studies. High methane partial pressure was previously successfully applied to stimulate growth, but it is not clear how different ANME subtypes and associated sulfate reducing bacteria (SRB) are affected by it. Here, we report growth of ANME/SRB in a membrane-capsule bioreactor inoculated with Eckernförde Bay sediment that combines high pressure incubation (10.1 MPa methane) and thorough mixing (100 rpm) with complete cell retention by a 0.2 µm membrane. Results were compared to previously obtained data from an ambient-pressure (0.101 MPa methane) bioreactor inoculated with the same sediment. Labelled-methane oxidation rates were not higher at 10.1 MPa, likely because measurements were done at ambient pressure. The subtype ANME-2a/b was abundant in both reactors, but subtype ANME-2c was only enriched at 10.1 MPa. SRB at 10.1 MPa mainly belonged to the SEEP-SRB2, Eel-1 group and Desulforomonadales and not to the typically found SEEP-SRB1. Increase of ANME-2a/b occurred in parallel with increase of SEEP-SRB2 which was previously only found associated with ANME-2c. Our results imply that the syntrophic association is flexible and that methane pressure and sulfide concentration influence growth of different ANME-SRB consortia. We also studied the effect of elevated methane pressure on methane production and oxidation by a mixture of methanogenic and sulfate-reducing sludge. Here, methane oxidation rates decreased and were not coupled to sulfide production, indicating trace methane oxidation during net methanogenesis and not anaerobic methane oxidation, even at high methane partial pressure.
Microbial dynamics during and after in situ chemical oxidation of chlorinated solvents
Sutton, N.B. ; Atashgahi, S. ; Wal, van der, J. ; Wijn, G. ; Grotenhuis, J.T.C. ; Smidt, H. ; Rijnaarts, H. - \ 2015
Groundwater 53 (2015)2. - ISSN 0017-467X - p. 261 - 270.
diesel-contaminated soil - 16s ribosomal-rna - real-time pcr - community structure - dnapl source - dechlorination - dehalococcoides - trichloroethene - bioremediation - genes
In situ chemical oxidation (ISCO) followed by a bioremediation step is increasingly being considered as an effective biphasic technology. Information on the impact of chemical oxidants on organohalide respiring bacteria (OHRB), however, is largely lacking. Therefore, we used quantitative PCR (qPCR) to monitor the abundance of OHRB (Dehalococcoides mccartyi, Dehalobacter, Geobacter, and Desulfitobacterium) and reductive dehalogenase genes (rdh; tceA, vcrA, and bvcA) at a field location contaminated with chlorinated solvents prior to and following treatment with sodium persulfate. Natural attenuation of the contaminants tetrachloroethene (PCE) and trichloroethene (TCE) observed prior to ISCO was confirmed by the distribution of OHRB and rdh genes. In wells impacted by persulfate treatment, a 1 to 3 order of magnitude reduction in the abundances of OHRB and complete absence of rdh genes was observed 21 days after ISCO. Groundwater acidification (pH500 mV) due to persulfate treatment were significant and contributed to disruption of the microbial community. In wells only mildly impacted by persulfate, a slight stimulation of the microbial community was observed, with more than 1 order of magnitude increase in the abundance of Geobacter and Desulfitobacterium 36 days after ISCO. After six months, regeneration of the OHRB community occurred, however, neither D. mccartyi nor any rdh genes were observed, indicating extended disruption of biological natural attenuation (NA) capacity following persulfate treatment. For full restoration of biological NA activity, additional time may prove sufficient; otherwise addition electron donor amendment or bioaugmentation may be required.
Advancing projections of phytoplankton responses to climate change through ensemble modelling
Trolle, D. ; Elliott, J.A. ; Mooij, W.M. - \ 2014
Environmental Modelling & Software 61 (2014). - ISSN 1364-8152 - p. 371 - 379.
fresh-water cyanobacteria - shallow lakes - multimodel ensembles - environmental-change - community structure - blooms - restoration - temperature - predictions - challenges
A global trend of increasing health hazards associated with proliferation of toxin-producing cyanobacteria makes the ability to project phytoplankton dynamics of paramount importance. Whilst ensemble (multi-)modelling approaches have been used for a number of years to improve the robustness of weather forecasts this approach has until now never been adopted for ecosystem modelling. We show that the average simulated phytoplankton biomass derived from three different aquatic ecosystem models is generally superior to any of the three individual models in describing observed phytoplankton biomass in a typical temperate lake ecosystem, and we simulate a series of climate change projections. While this is the first multi-model ensemble approach applied for some of the most complex aquatic ecosystem models available, we consider it sets a precedent for what will become commonplace methodology in the future, as it enables increased robustness of model projections, and scenario uncertainty estimation due to differences in model structures.
Food plant and herbivore host species affect the outcome of intrinsic competition among parasitoid larvae
Poelman, E.H. ; Gols, R. ; Gumovsky, A.V. ; Cortesero, A.M. ; Dicke, M. ; Harvey, J.A. - \ 2014
Ecological Entomology 39 (2014)6. - ISSN 0307-6946 - p. 693 - 702.
cotesia-rubecula hymenoptera - endoparasitoid wasps - insect parasitoids - heliothis-virescens - community structure - braconidae - superparasitism - discrimination - solitary - lepidoptera
1. In nature, several parasitoid species often exploit the same stages of a common herbivore host species and are able to coexist despite competitive interactions amongst them. Less is known about the direct effects of resource quality on intrinsic interactions between immature parasitoid stages. The present study is based on the hypothesis that variation in the quality or type of plant resources on which the parasitoids indirectly develop may be complementary and thus facilitate niche segregation favouring different parasitoids in intrinsic competition under different dietary regimes. 2. The present study investigated whether two herbivore species, the cabbage butterflies Pieris brassicae and Pieris rapae (Pieridae), and the quality of two important food plants, Brassica oleracea and Brassica nigra (Brassicaceae), affect the outcome of intrinsic competition between their primary larval endoparasitoids, the gregarious Cotesia glomerata (Braconidae) and the solitary Hyposoter ebeninus (Ichneumonidae). 3. Hyposoter ebeninus is generally an intrinsically superior competitor over C.¿glomerata. However, C.¿glomerata survived more antagonistic encounters with H.¿ebeninus when both developed in P.¿brassicae rather than in P.¿rapae caterpillars, and while its host was feeding on B.¿nigra rather than B.¿oleracea. Moreover, H.¿ebeninus benefitted from competition by its higher survival in multiparasitised hosts. 4. These results show that both plant and herbivore species mediate the battleground on which competitive interactions between parasitoids are played out and may affect the outcomes of these interactions in ways that enable parasitoids to segregate their niches. This in turn may promote coexistence among parasitoid species that are associated with the same herbivore host.
Metaproteomics of our microbiome - Developing insight in function and activity in man and model systems
Kolmeder, C. ; Vos, W.M. de - \ 2014
Journal of Proteomics 97 (2014). - ISSN 1874-3919 - p. 3 - 16.
3-dimensional peptide fractionation - gastrointestinal-tract microbiota - tandem mass-spectrometry - human gut microbiome - in-vitro model - escherichia-coli - environmental proteomics - intestinal microbiota - community structure - effective recovery
We are all colonized by a large microbiome, a complex set of microbes that have intimate associations with us. Culture-based approaches have provided insights in the complexity of the microbial communities living on surfaces inside and outside the body. However, the application of high-throughput sequencing technologies has identified large numbers of community members at both the phylogenetic and the (meta-)genome level. The latter allowed defining a reference set of several millions of mainly bacterial genes and provided the basis for developing approaches to target the activity and function of the human microbiome with proteomic techniques. Moreover, recent improvements in protein and peptide separation efficiencies and highly accurate mass spectrometers have promoted the field of metaproteomics, the study of the collective proteome of microbial communities. We here review the approaches that have been developed to study the human metaproteomes, focusing on intestinal tract and body fluids. Moreover, we complement these by considering metaproteomic studies in mouse and other model systems offering the option to study single species or simple consortia. Finally, we discuss present and future avenues that may be used to advance the application of metaproteomic approaches to further improve our understanding of the microbes inside and around our body. This article is part of a Special Issue entitled: Trends in Microbial Proteomics
Diversity patterns of leaf-associated aquatic hyphomycetes along a broad latitudinal gradient
Jabiol, J. ; Bruder, A. ; Gessner, M.O. ; Makkonen, M. ; McKie, B.G. ; Peeters, E.T.H.M. ; Vos, V.C.A. ; Chauvet, E. - \ 2013
Fungal Ecology 6 (2013)5. - ISSN 1754-5048 - p. 439 - 448.
species-diversity - community structure - fungal communities - stream - litter - biodiversity - temperature - leaves - colonization - decomposition
Information about the global distribution of aquatic hyphomycetes is scarce, despite the primary importance of these fungi in stream ecosystem functioning. In particular, the relationship between their diversity and latitude remains unclear, due to a lack of coordinated surveys across broad latitudinal ranges. This study is a first report on latitudinal patterns of aquatic hyphomycete diversity associated with native leaf-litter species in five streams located along a gradient extending from the subarctic to the tropics. Exposure of leaf litter in mesh bags of three different mesh sizes facilitated assessing the effects of including or excluding different size-classes of litter-consuming invertebrates. Aquatic hyphomycete evenness was notably constant across all sites, whereas species richness and diversity, expressed as the Hill number, reached a maximum at mid-latitudes (Mediterranean and temperate streams). These latitudinal patterns were consistent across litter species, despite a notable influence of litter identity on fungal communities at the local scale. As a result, the bell-shaped distribution of species richness and Hill diversity deviated markedly from the latitudinal patterns of most other groups of organisms. Differences in the body-size distribution of invertebrate communities colonizing the leaves had no effect on aquatic hyphomycete species richness, Hill diversity or evenness, but invertebrates could still influence fungal communities by depleting litter, an effect that was not captured by the design of our experiment. (C) 2013 Elsevier Ltd and The British Mycological Society. All rights reserved.
Comparison of cyanobacterial and green algal growth rates at different temperatures
Lurling, M. ; Faassen, E.J. ; Kosten, S. ; Eshetu, Z. ; Huszar, V.M. - \ 2013
Freshwater Biology 58 (2013)3. - ISSN 0046-5070 - p. 552 - 559.
fresh-water zooplankton - climate-change - shallow lakes - community structure - microcystis-aeruginosa - phytoplankton - blooms - allelopathy - nutrient - daphnia
1.The hypothesis that cyanobacteria have higher optimum growth temperatures and higher growth rates at the optimum as compared to chlorophytes was tested by running a controlled experiment with eight cyanobacteria species and eight chlorophyte species at six different temperatures (20-35°C) and by performing a literature survey. 2.In the experiment, all organisms except the chlorophyte Monoraphidium minutum grew well up to 35°C. The chlorophyte Chlamydomonas reinhardtii was the fastest-growing organism over the entire temperature range (20-35°C). 3.Mean optimum growth temperatures were similar for cyanobacteria (29.2°C) and chlorophytes (29.2°C). These results are concordant with published data, yielding slightly higher mean optimum growth temperatures for cyanobacteria (27.2°C) than for chlorophytes (26.3°C). 4.Mean growth rates of cyanobacteria at 20°C (0.42day-1) were significantly lower than those of chlorophytes at 20°C (0.62day-1). However, at all other temperatures, there were no differences between mean growth rates of cyanobacteria and chlorophytes. 5.Mean growth rates at the optimum temperature were similar for cyanobacteria (0.92day-1) and chlorophytes (0.96day-1). However, analysis of published data revealed that growth rates of cyanobacteria (0.65day-1) were significantly lower than those of chlorophytes (0.93day-1) at their optimum temperatures. 6.Although climate warming will probably lead to an intensification of cyanobacterial blooms, our results indicate that this might not be as a result of higher growth rates of cyanobacteria compared with their chlorophyte competitors. The competitive advantage of cyanobacteria can more likely be attributed to their ability to migrate vertically and prevent sedimentation in warmer and more strongly stratified waters and to their resistance to grazing, especially when warming reduces zooplankton body size. © 2012 Blackwell Publishing Ltd.
Nitrogen Addition and Warming Independently Influence the Belowground Micro-Food Web in a Temperate Steppe
Li, Q. ; Bai, H. ; Liang, W. ; Xia, J. ; Wan, S. ; Putten, W.H. van der - \ 2013
PLoS ONE 8 (2013)3. - ISSN 1932-6203
climate-change manipulations - species composition - community structure - plant-communities - organic-matter - northern china - soil nematodes - global change - elevated co2 - deposition
Climate warming and atmospheric nitrogen (N) deposition are known to influence ecosystem structure and functioning. However, our understanding of the interactive effect of these global changes on ecosystem functioning is relatively limited, especially when it concerns the responses of soils and soil organisms. We conducted a field experiment to study the interactive effects of warming and N addition on soil food web. The experiment was established in 2006 in a temperate steppe in northern China. After three to four years (2009–2010), we found that N addition positively affected microbial biomass and negatively influenced trophic group and ecological indices of soil nematodes. However, the warming effects were less obvious, only fungal PLFA showed a decreasing trend under warming. Interestingly, the influence of N addition did not depend on warming. Structural equation modeling analysis suggested that the direct pathway between N addition and soil food web components were more important than the indirect connections through alterations in soil abiotic characters or plant growth. Nitrogen enrichment also affected the soil nematode community indirectly through changes in soil pH and PLFA. We conclude that experimental warming influenced soil food web components of the temperate steppe less than N addition, and there was little influence of warming on N addition effects under these experimental conditions.
Competition increases sensitivity of wheat (Triticum aestivum) to biotic plant-soil feedback
Hol, W.H.G. ; Boer, W. de; Hooven, F. ten; Putten, W.H. van der - \ 2013
PLoS ONE 8 (2013)6. - ISSN 1932-6203
community structure - grassland - ecology - ecosystems - diversity - pathogens - diseases - fungi
Plant-soil feedback (PSF) and plant competition play an important role in structuring vegetation composition, but their interaction remains unclear. Recent studies suggest that competing plants could dilute pathogenic effects, whereas the standing view is that competition may increase the sensitivity of the focal plant to PSF. In agro-ecosystems each of these two options would yield contrasting outcomes: reduced versus enhanced effects of weeds on crop biomass production. To test the effect of competition on sensitivity to PSF, we grew Triticum aestivum (Common wheat) with and without competition from a weed community composed of Vicia villosa, Chenopodium album and Myosotis arvensis. Plants were grown in sterilized soil, with or without living field inoculum from 4 farms in the UK. In the conditioning phase, field inocula had both positive and negative effects on T. aestivum shoot biomass, depending on farm. In the feedback phase the differences between shoot biomass in T. aestivum monoculture on non-inoculated and inoculated soils had mostly disappeared. However, T. aestivum plants growing in mixtures in the feedback phase were larger on non-inoculated soil than on inoculated soil. Hence, T. aestivum was more sensitive to competition when the field soil biota was present. This was supported by the statistically significant negative correlation between shoot biomass of weeds and T. aestivum, which was absent on sterilized soil. In conclusion, competition in cereal crop-weed systems appears to increase cereal crop sensitivity to soil biota.
Tropical secondary forest management influences frugivorous bat composition, abundance and fruit consumption in Chiapas, Mexico
Vleut, I. ; Levy-Tacher, S.I. ; Boer, W.F. de; Galindo-Gonzalez, J. - \ 2013
PLoS ONE 8 (2013)10. - ISSN 1932-6203
rain-forest - community structure - neotropical forest - foraging habitat - scattered trees - seed dispersal - eating bats - succession - vegetation - diversity
Most studies on frugivorous bat assemblages in secondary forests have concentrated on differences among successional stages, and have disregarded the effect of forest management. Secondary forest management practices alter the vegetation structure and fruit availability, important factors associated with differences in frugivorous bat assemblage structure, and fruit consumption and can therefore modify forest succession. Our objective was to elucidate factors (forest structural variables and fruit availability) determining bat diversity, abundance, composition and species-specific abundance of bats in (i) secondary forests managed by Lacandon farmers dominated by Ochroma pyramidale, in (ii) secondary forests without management, and in (iii) mature rain forests in Chiapas, Southern Mexico. Frugivorous bat species diversity (Shannon H’) was similar between forest types. However, bat abundance was highest in rain forest and O. pyramidale forests. Bat species composition was different among forest types with more Carollia sowelli and Sturnira lilium captures in O. pyramidale forests. Overall, bat fruit consumption was dominated by early-successional shrubs, highest late-successional fruit consumption was found in rain forests and more bats consumed early-successional shrub fruits in O. pyramidale forests. Ochroma pyramidale forests presented a higher canopy openness, tree height, lower tree density and diversity of fruit than secondary forests. Tree density and canopy openness were negatively correlated with bat species diversity and bat abundance, but bat abundance increased with fruit abundance and tree height. Hence, secondary forest management alters forests’ structural characteristics and resource availability, and shapes the frugivorous bat community structure, and thereby the fruit consumption by bats
Top-down and bottom-up control of large herbivore populations: a review of natural and human-induced influences
Gandiwa, E. - \ 2013
Tropical conservation science 6 (2013)4. - ISSN 1940-0829 - p. 493 - 505.
gonarezhou national-park - community structure - african savannas - food-web - wildlife conservation - aboriginal overkill - trophic cascades - southern africa - body-size - ecosystems
The question whether animal populations are top-down and/or bottom-up controlled has motivated a thriving body of research over the past five decades. In this review I address two questions: 1) how do top-down and bottom-up controls influence large herbivore populations? 2) How do human activities and control systems influence the top-down and bottom-up processes that affect large herbivore population dynamics? Previous studies suggest that the relative influence of top-down vs. bottom-up control varies among ecosystems at the global level, with abrupt shifts in control possible in arid and semi-arid regions during years with large differences in rainfall. Humans as super-predators exert top-down control on large wild herbivore abundances through hunting. However, through fires and livestock grazing, humans also exert bottom-up controls on large wild herbivore abundances through altering resource availability, which influences secondary productivity. This review suggests a need for further research, especially on the human-induced top-down and bottom-up control of animal populations in different terrestrial ecosystems.
Coupling bioturbation activity to metal (Fe and Mn) profiles in situ
Teal, L.R. ; Parker, E.R. ; Solan, M. - \ 2013
Biogeosciences 10 (2013). - ISSN 1726-4170 - p. 2365 - 2378.
organism-sediment relations - marine-sediments - trace-metals - hydraulic activities - nereis-diversicolor - luminophore tracers - porewater advection - community structure - arenicola-marina - spatial scales
The relative contributions that species assemblages, abiotic variables, and their interactions with one another make to ecosystem properties are recognised but are seldom considered simultaneously, within context, and at the appropriate spatio-temporal scales. Here, we combine fluorescent time-lapse sediment profile imaging (f-SPI) and diffusion gradient thin gels (DGT) to examine, in situ, the link between an important benthic ecosystem process (bioturbation) and the availability (profiles) of Fe and Mn. Whilst the combination of these methodologies (fg-SPI) was successful in gathering high-resolution in situ data of bioturbation activity and Fe/Mn profiles simultaneously, we show that the mechanistic basis of how the infaunal community mediate Fe and Mn is difficult to reconcile because of the spatio-temporal differences between particle and porewater mixing. This mismatch means that the consideration of these mechanistic processes in isolation is likely to limit our interpretative capacity of how infaunal communities mediate various biogeochemical processes in the natural environment. Moreover, the combination of multiple technologies, process based simulation modelling and generalised additive statistical modelling achieved here, emphasises the importance of simultaneously considering additional factors that influence benthic chemistry, in particular bioirrigation and tidal flushing of the sediment profile. Our findings highlight a pressing need to determine how the relative importance of multiple abiotic and biotic factors act in concert to alter major biogeochemical pathways across a variety of contexts and habitats.
Substratum associations of benthic invertebrates in lowland and mountain streams
Schröder, M. ; Kiesel, J. ; Schattmann, A. ; Jähnig, S.C. ; Lorenz, A.W. ; Kramm, S. ; Keizer-Vlek, H.E. ; Rolauffs, P. ; Graf, W. ; Leitner, P. ; Hering, D. - \ 2013
Ecological Indicators 30 (2013). - ISSN 1470-160X - p. 178 - 189.
macroinvertebrate assemblages - community structure - species assemblages - habitat type - bioassessment - rivers - reach - microdistribution - quality - sites
The preferences of aquatic invertebrate species for specific substrata at the river bottom have been subject of many studies. Several authors classified the substratum preferences of species or higher taxonomic units. Most of these compilations, however, are based on literature analyses and expert knowledge as opposed to the analysis of original data. To enhance our knowledge of invertebrate substratum preferences, we applied a ‘Multi-level pattern’ analysis based on almost 1000 substrate-specific invertebrate samples. The samples were taken in 18 streams in Germany, the Netherlands and Austria, comprising a total of 40 sampling sites and equally covering lowland and mountain streams. The main objectives of our analysis were (I) to derive substratum preferences of taxa in lowland and mountain streams, (II) to compare the preferences with existing data and (III) to compare species substratum associations between lowland and mountain streams. Of the 290 taxa analyzed, 188 were associated significantly to specific substrata. Twenty-five taxa in lowland streams and 51 taxa in mountain streams prefer one or two substratum types (of nine substratum types considered in total). In contrast, 112 species (mountain streams n = 84, lowland streams n = 28) are associated significantly with a broader range of substrata. We compared the classifications derived from our data analysis with those provided in the freshwaterecology.info database (www.freshwaterecology.info). Our results support the existing classifications of substratum preferences in most cases (70%). For 25 species, substratum preferences for both lowland and mountain streams were derived, many of them indicating different substratum associations in the two stream groups. As substratum preferences differed between closely related species, preferences should always be given at the species level as opposed to coarser taxonomic units
Editorial: Global in scope and regionally rich: an IndiSeas workshop helps shape the future of marine ecosystem indicators
Shin, Y.J. ; Bundy, A. ; Piet, G.J. - \ 2012
Reviews in Fish Biology and Fisheries 22 (2012)3. - ISSN 0960-3166 - p. 835 - 845.
size-based indicators - cusum control charts - to-end models - fisheries management - community structure - ecological status - climate-change - fuzzy-logic - food webs - catch
This report summarizes the outcomes of an IndiSeas workshop aimed at using ecosystem indicators to evaluate the status of the world’s exploited marine ecosystems in support of an ecosystem approach to fisheries, and global policy drivers such as the 2020 targets of the Convention on Biological Diversity. Key issues covered relate to the selection and integration of multi-disciplinary indicators, including climate, biodiversity and human dimension indicators, and to the development of data- and model-based methods to test the performance of ecosystem indicators in providing support for fisheries management. To enhance the robustness of our cross-system comparison, unprecedented effort was put in gathering regional experts from developed and developing countries, working together on multi-institutional survey datasets, and using the most up-to-date ecosystem models.