Elevated ozone and nitrogen deposition affect nitrogen pools of subalpine grassland

Bassin, Seraina; Käch, David; Valsangiacomo, Alain; Mayer, Jochen; Oberholzer, Hans‐Rudolf; Volk, Matthias; Fuhrer, Jürg

doi:10.1016/j.envpol.2015.02.038

Cited by 14 publications

(15 citation statements)

References 54 publications

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“…There is evidence of negative effects of O 3 on soil nematodes (Bao, Li, Hua, Zhao, & Liang, 2014), collembolans, enchytraeids, and soil mites (Schrader, Bender, & Weigel, 2009), which could further slow decomposition. In the long run, reduced degradability of litter leads to increased immobilization of C and N in recalcitrant soil fractions, as observed in soils of forests (Holmes, Zak, Pregitzer, & King, 2006) and montane grassland (Bassin et al., 2015), which feeds back to plants via altered nutrient availability. However, such effects are subtle and vary across sources of litter and environmental conditions.…”

Section: Changes In Soil Microbiota and Nutrient Cyclingmentioning

confidence: 99%

Current and future ozone risks to global terrestrial biodiversity and ecosystem processes

Fuhrer

Martin

Mills

et al. 2016

Ecology and Evolution

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Risks associated with exposure of individual plant species to ozone (O3) are well documented, but implications for terrestrial biodiversity and ecosystem processes have received insufficient attention. This is an important gap because feedbacks to the atmosphere may change as future O3 levels increase or decrease, depending on air quality and climate policies. Global simulation of O3 using the Community Earth System Model (CESM) revealed that in 2000, about 40% of the Global 200 terrestrial ecoregions (ER) were exposed to O3 above thresholds for ecological risks, with highest exposures in North America and Southern Europe, where there is field evidence of adverse effects of O3, and in central Asia. Experimental studies show that O3 can adversely affect the growth and flowering of plants and alter species composition and richness, although some communities can be resilient. Additional effects include changes in water flux regulation, pollination efficiency, and plant pathogen development. Recent research is unraveling a range of effects belowground, including changes in soil invertebrates, plant litter quantity and quality, decomposition, and nutrient cycling and carbon pools. Changes are likely slow and may take decades to become detectable. CESM simulations for 2050 show that O3 exposure under emission scenario RCP8.5 increases in all major biomes and that policies represented in scenario RCP4.5 do not lead to a general reduction in O3 risks; rather, 50% of ERs still show an increase in exposure. Although a conceptual model is lacking to extrapolate documented effects to ERs with limited or no local information, and there is uncertainty about interactions with nitrogen input and climate change, the analysis suggests that in many ERs, O3 risks will persist for biodiversity at different trophic levels, and for a range of ecosystem processes and feedbacks, which deserves more attention when assessing ecological implications of future atmospheric pollution and climate change.

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Section: Changes In Soil Microbiota and Nutrient Cyclingmentioning

confidence: 99%

Current and future ozone risks to global terrestrial biodiversity and ecosystem processes

Fuhrer

Martin

Mills

et al. 2016

Ecology and Evolution

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“…Other possible explanations for decreased NH 4 concentrations may include increased plant uptake of N, increased microbial biomass (Kanerva et al, 2006;Bassin et al, 2015) or decreased N 2 fixation rate (Pausch et al, 1996;Li et al, 2013). Increased N concentrations of leaves in response to elevated O 3 have been observed in trees and grasslands (Wittig et al, 2009;Bassin et al, 2015), but this has rather been attributed to increased retranslocation of N after early senescence of part of the leaves, reduced plant size (Wittig et al, 2009) and reduced N resorption from senescing leaves (Uddling et al, 2006).…”

Section: Ozone Impacts On N Cyclingmentioning

confidence: 99%

“…Increased N concentrations of leaves in response to elevated O 3 have been observed in trees and grasslands (Wittig et al, 2009;Bassin et al, 2015), but this has rather been attributed to increased retranslocation of N after early senescence of part of the leaves, reduced plant size (Wittig et al, 2009) and reduced N resorption from senescing leaves (Uddling et al, 2006). Moreover, leaf N concentrations of the green sedge leaves in the final summer of our experiment were, lower at NFA+35/10 than at ambient O 3 (S. Toet, unpublished data), and, together, with no significant O 3 effects on sedge green leaf density and root biomass imply that increased plant uptake of N at elevated O 3 is not very likely.…”

Section: Ozone Impacts On N Cyclingmentioning

confidence: 99%

“…This may be through reduced litter quantity or quality, although effects of O 3 on nitrification, denitrification, microbial biomass and plant uptake of N have also been reported (Wittig et al, 2009;Li et al 2010;Bhatia et al, 2011;Pereira et al, 2011;Bassin et al, 2015). In nitrogen (N) poor systems such as peatlands, reduced below-ground allocation of N could cause reduced activity of heterotrophic soil microorganisms, such as methanogens (Kanerva et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

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How does elevated ozone reduce methane emissions from peatlands?

Toet

Oliver

Ineson

et al. 2017

Science of The Total Environment

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“…Belowground root biomass was assessed from soil cores covering a subset of the monoliths (Volk et al, 2014). DM masses were expressed as grams of carbon per square meter (g C m −2 ) based on plant biomass C concentration (C/N elemental analyzer measurements; Bassin et al, 2015). Masses of four plots each were combined and averaged to match the lumping rules developed for soil sampling (compare below).…”

Section: Plant Yield C Contentmentioning

confidence: 99%

Subalpine grassland carbon balance during 7 years of increased atmospheric N deposition

2016

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Abstract. Air pollution agents interact when affecting biological sinks for atmospheric CO 2 , e.g., the soil organic carbon (SOC) content of grassland ecosystems. Factors favoring plant productivity, like atmospheric N deposition, are usually considered to favor SOC storage. In a 7-year experiment in subalpine grassland under N-and O 3 -deposition treatment, we examined C fluxes and pools. Total N deposition was 4, 9, 14, 29 and 54 kg N ha −1 yr −1 (N4, N9, etc.); annual mean phytotoxic O 3 dose was 49, 65 and 89 mmol m −2 projected leaf area. We hypothesized that between years SOC of this mature ecosystem would not change in control treatments and that effects of air pollutants are similar for plant yield, net ecosystem productivity (NEP) and SOC content, leading to SOC content increasing with N deposition. Cumulative plant yield showed a significant N and N × N effect (+38 % in N54) but no O 3 effect. In the control treatment SOC increased significantly by 9 % in 7 years. Cumulative NEP did show a strong, hump-shaped response pattern to N deposition with a +62 % increase in N14 and only +39 % increase in N54 (N effect statistically not significant, N × N interaction not testable). SOC had a similar but not significant response to N, with highest C gains at intermediate N deposition rates, suggesting a unimodal response with a marginal (P = 0.09) N × N interaction. We assume the strong, pollutant-independent soil C sink developed as a consequence of the management change from grazing to cutting. The non-parallel response of SOC and NEP compared to plant yield under N deposition is likely the result of increased respiratory SOC losses, following mitigated microbial N-limitation or priming effects, and a shift in plant C allocation leading to smaller C input from roots.

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Elevated ozone and nitrogen deposition affect nitrogen pools of subalpine grassland

Cited by 14 publications

References 54 publications

Current and future ozone risks to global terrestrial biodiversity and ecosystem processes

Current and future ozone risks to global terrestrial biodiversity and ecosystem processes

How does elevated ozone reduce methane emissions from peatlands?

Subalpine grassland carbon balance during 7 years of increased atmospheric N deposition

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