Barren, metal-contaminated soils lack plants and root exudate inputs, exhibit low microbial abundance and functioning, and often require soil revitalization to revegetate. While the effects of ...simulated root exudates (SRE) have been investigated in uncontaminated, vegetated soils, their potential for remediating post-industrial barren, contaminated soils has not been examined or leveraged. We asked whether priming brownfield soils with a laboratory-prepared SRE solution stimulates native soil microbial metabolism and functioning and how long the effects last. Moreover, we compared a cost-effective single SRE addition to repeated SRE additions. We collected soils from a metal-contaminated, abandoned industrial rail yard (barren and vegetated sites) and a vegetated agricultural reference site, established microcosms, and treated the soils with either a single or repeated SRE addition/s. By day 30, SRE-enriched barren, brownfield soils showed significantly higher soil respiration rates than the untreated control soils. Phosphatase activities were significantly higher even 210 days after a single SRE addition. Plants were introduced 282 days after the single SRE addition. The average shoot height (16 ± 0.3cm) and total plant biomass (0.5 ± 0.02g) of plants grown in single addition SRE enriched barren soil were significantly higher than the controls (9 ± 0.9cm and 0.3 ± 0.02g, respectively). The increased soil microbial functioning and productivity indicate that a single SRE application holds promise as a field-ready technology to revitalize barren, poorly functioning brownfield soils. SRE application may also be a pragmatic and innovative approach to enable successful phytoremediation and re-greening of industrial barrens.
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•Barren, contaminated, railyard soil was treated with simulated root exudates (SREs)•By day 30, SRE-enriched soil showed a higher soil respiration rate than the control•Phosphatase activities were higher in SRE-enriched soil, even after 210 days•Plant biomass and shoot height were higher in SRE-enriched soil•Single SRE addition was effective and showed potential for field application
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Alpine grasslands are essential for carbon sequestration and food supply for domestic and wild herbivores inhabiting mountainous areas worldwide. These biomes, however, are alternatively threatened ...by the abandonment of agricultural and livestock practices leading to a fast-growing shrubification process while other mountain grasslands are suffering from the impacts of overgrazing. The functioning of alpine meadow ecosystems is primarily driven by climatic conditions, land-use legacies and grazing. However, although it is critically important, the role of large herbivores on the aboveground biomass and protein content of palatable plants is poorly understood for most alpine meadows. In this work, we explore the effects of grazing on grassland vegetation at two different spatial and temporal scales in the Eastern Pyrenees, Spain. Remote sensing was used to assess the effect of high and moderate grazing (HG and MG respectively) on grass biomass using the leaf area index (LAI) at the meso-scale (patches between 2.3 and 38.7 ha). We also explored the impact of null (NG), overgrazing (MO, mimicked overgrazing) and high (HG) grazing intensities at local scale setting eighteen 1 m2 exclusion boxes in six meadows (three boxes each) commonly used by domestic and wild ungulates. Historical satellite data showed that LAI values are greater in high than in low grazed areas (HG, mean = 0.66, LG, mean = 0.55). Along the same lines, high and moderate grazing pressures improved biomass production at the local-scale (HG, mean = 590.3 g/m2, MO, mean = 389.3 g/m2 and NG, mean = 110.8 g/m2). Crude protein content reached higher values under MO pressure than under HG pressure. Our results confirm that grazing intensity exerts significant changes on the above-ground biomass production and the protein content of plants consumed by domestic (cattle and horses) and wild ungulates (Southern Chamois, Rupicapra pyrenaica). We can conclude that ungulates sustain biomass and nutritive values of grass exerting a negligible effect on biomass and protein content of woody vegetation. Our results will inform management guidelines to support profitable grazing activities and promote conservation of the open landscapes in the alpine ecosystems under the current global change scenario.
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•We quantified the impact of grazing on biomass production and nutritional value of meadows.•Moderate grazing increases biomass production and protein content of grass.•Biomass and protein contents of woody plants was not affected by grazing.•High grazing reduces biomass production but increases protein content of grass.•Grazing management is important to keep the nutritional value of alpine meadows.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Identifying inorganic and organic soil contaminants in urban brownfields can give insights into the adverse effects of industrial activities on soil function, ecological health, and environmental ...quality. Liberty State Park in Jersey City (N.J., USA) once supported a major rail yard that had dock facilities for both cargo and passenger service; a portion remains closed to the public, and a forest developed and spread in this area. The objectives of this study were to: 1) characterize the organic and inorganic compounds in Liberty State Park soils and compare the findings to an uncontaminated reference site (Hutcheson Memorial Forest); and 2) identify differences between the barren low-functioning areas and the forested high-functioning areas of the brownfield. Soil samples were solvent-extracted, fractionated, and analyzed by gas chromatography–mass spectrometry and subjected to loss-on-ignition, pyrolysis-gas chromatography–mass spectrometry, inductively-coupled-plasma mass spectrometry, and optical microscopy analyses. Compared to soil from the reference site, the forested soils in Liberty State Park contained elevated percentages of organic matter (30–45%) and more contaminants, such as fossil-fuel-derived hydrocarbons and coal particles. Microscopy revealed bituminous and anthracite coal, coke, tar/pitch, and ash particles. Barren and low-functioning site 25R had a similar organic contaminant profile but contained a higher metal load than other Liberty State Park sites and also lacked higher plant indicators. These can obscure the signatures of contaminants, and data from adjacent barren and vegetated sites are valuable references for soils studies. A deeper understanding of the chemistry, biochemistry, and ecology of barren soils can be leveraged to prevent land degradation and to restore dysfunctional and phytotoxic soils.
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•We characterized organic and inorganic substances at a major urban brownfield site.•We detected abundant petroleum- and coal-derived biomarkers and PAHs in the soil.•Both barren low-functioning and forested soils contained similar organic compounds.•The barren site featured very high heavy metal loads and dormant microbial life.•Chemical and ecological studies are critical to brownfield restoration efforts.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
1. Allometric theory makes specific predictions about how density, and consequently biomass, scale with organism size within trophic levels, across trophic levels and across food webs. 2. ...Diversity-yield relationships suggest that more diverse food webs can sometimes support more biomass through mechanisms involving niche complementarity or selection effects that are sometimes attributed to organism size. 3. We combine the above two approaches and show that, generally, density and biomass scale with organism size within and between trophic levels as predicted by allometric theory. Further, food webs converged in total biomass despite persistent differences in the composition and size of the organisms among food webs; species richness explained deviations from the constant yield of biomass expected from size-abundance relationships. 4. Our results suggest that organism size plays only a transient role in controlling community biomass because population increases or decreases lead to rapid convergence in biomass. Species richness affects community biomass independently by effectively increasing the mass of organisms that can be supported in a given productivity regime.
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Microbial communities play a pivotal role in soil nutrient cycling, which is affected by nitrogen loading on soil fungi and particularly mycorrhizal fungi. In this experiment, we evaluated the ...effects of allochthonous nitrogen addition on soil bacteria and fungi in two geographically distinct but structurally similar scrub oak forests, one in Florida (FL) and one in New Jersey (NJ). We applied allochthonous nitrogen as aqueous NH
4NO
3 in three concentrations (0
kg
ha
−1
yr
−1 (deionized water control), 35
kg
ha
−1
yr
−1 and 70
kg
ha
−1
yr
−1) via monthly treatments over the course of 1
yr. We applied treatments to replicated 1
m
2 plots, each at the base of a reference scrub oak tree (
Quercus myrtifolia in FL and
Q. ilicifolia in NJ). We measured microbial community response by monitoring: bacterial and fungal biomass using substrate induced respiration, and several indicators of community composition, including colony and ectomycorrhizal morphotyping and molecular profiling using terminal restriction fragment length polymorphism (TRFLP). Bacterial colony type richness responded differently to nitrogen treatment in the different sites, but ectomycorrhizal morphotype richness was not affected by nitrogen or location. Both experimental sites were dominated by fungi, and FL consistently supported more bacterial and fungal biomass than NJ. Bacterial biomass responded to nitrogen addition, but only in FL. Fungal biomass did not respond significantly to nitrogen addition at either experimental site. The composition of the bacterial community differed between nitrogen treatments and experimental sites, while the composition of the fungal community did not. Our results imply that bacterial communities may be more sensitive than fungi to intense pulses of nitrogen in sandy soils.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
•We measured the belowground effects of adelgid infestation on eastern hemlock.•Adelgid infestation decreased ectomycorrhizal colonization of fine roots.•Infestation also decreased bacterial ...colonization of hemlock roots.•Infested trees had lower root C, but did not differ in N and C:N ratios.•Forest restoration may be more difficult if belowground communities are altered.
While the impact of aboveground herbivores on plant biomass and fitness has received considerable attention, there has been far less research on the corresponding belowground impacts. The belowground effects of aboveground feeding may be particularly noticeable for invasive and/or outbreaking herbivore species that reach high densities and can cause major damage and sometimes death. The hemlock woolly adelgid, Adelges tsugae, is an invasive pest on the eastern seaboard of the United States that feeds on a native shade-tolerant conifer, the eastern hemlock Tsuga canadensis. Trees rapidly decline and die following infestation, and the invasion of this insect has devastated hemlock populations from Georgia in the south to Maine in the north. Despite their substantial impact on tree health, we are unaware of any research into the adelgid’s effect on hemlock roots and the surrounding rhizosphere. We report the results of research assessing ectomycorrhizal root colonization, rhizosphere bacterial abundance, and root C:N ratios of infested and uninfested T. canadensis. We found that adelgid infestation decreased the percentage of root material colonized by ectomycorrhizal fungi by more than 67%. Rhizosphere bacterial abundance on fine roots was 25% lower on adelgid-infested versus uninfested trees, and roots of adelgid-infested trees contained significantly less carbon. Our results demonstrate that aboveground adelgid infestation can affect hemlock root composition and alter belowground interactions with ectomycorrhizal fungi and bacteria. This information demonstrates that above-belowground linkages can transmit the impact of herbivory far from the site of localized damage.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
A fixed-film (biofilm) reactor was designed and its performance was determined at various retention times. The goal was to find the optimal retention time for recycling plant nutrients in an advanced ...life support system, to minimize the size, mass, and volume (hold-up) of a production model. The prototype reactor was tested with aqueous leachate from wheat crop residue at 24, 12, 6, and 3 h hydraulic retention times (HRTs). Biochemical oxygen demand (BOD), nitrates and other plant nutrients, carbohydrates, total phenolics, and microbial counts were monitored to characterize reactor performance. BOD removal decreased significantly from 92% at the 24 h HRT to 73% at 3 h. Removal of phenolics was 62% at the 24 h retention time, but 37% at 3 h. Dissolved oxygen concentrations, nitric acid consumption, and calcium and magnesium removals were also affected by HRT. Carbohydrate removals, carbon dioxide (CO2) productions, denitrification, potassium concentrations, and microbial counts were not affected by different retention times. A 6 h HRT will be used in future studies to determine the suitability of the bioreactor effluent for hydroponic plant production.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
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BFBNIB, DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
30.
No Paradox for Invasive Plants Meisner, Annelein; de Boer, Wietse; Hol, W. H. Gera ...
Science (American Association for the Advancement of Science),
08/2009, Volume:
325, Issue:
5942
Journal Article
Peer reviewed
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