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ISA NOxSOxPM Ecology (2018)

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The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Estimating base cation weathering rates in the USA: challenges of uncertain soil mineralogy and specific surface area with applications of the profile model

Author: Whitfield, C.J., Phelan, J.N., Buckley, J., CLark, C.M., Guthrie, S., Lynch, J.A. (2018) Water, Air, and Soil Pollution 229:61. HERO ID: 4288664


The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Nitrogen additions affect litter quality and soil biochemical properties in a peatland of Northeast China

Authors: Song, Y; Song, C; Meng, H; Swarzenski, CM; Wang, X; Tan, W (2017) Ecological Engineering 100:175-185. HERO ID: 3847909

[Less] Nitrogen (N) is a limiting nutrient in many peatland ecosystems. Enhanced N deposition, a major component . . . [More] Nitrogen (N) is a limiting nutrient in many peatland ecosystems. Enhanced N deposition, a major component of global climate change, affects ecosystem carbon (C) balance and alters soil C storage by changing plant and soil properties. However, the effects of enhanced N deposition on peatland ecosystems are poorly understood. We conducted a two-year N additions field experiment in a peatland dominated by Eriophorum vaginatum in the Da Xing'an Mountains, Northeast China. Four levels of N treatments were applied: (1) CK (no N added), (2) N1 (6 g N m(-2) yr(-1)), (3) N2 (12 g N m(-2) yr(-1)), and (4) N3 (24 gN m(-2) yr(-1)). Plant and soil material was harvested at the end of the Second growing season. N additions increased litter N and phosphorus (P) content, as well as S-glucosidase, invertase, and acid-phosphatase activity, but decreased litter C:N and C:P ratios. Litter carbon content remained unchanged. N additions increased available NH4+-N and NO3--N as well as total Gram-positive (Gram+), Gram-negative (Gram-), and total bacterial phospholipid fatty acids (PLFA) in shallow soil (0-15 cm depth). An increase in these PLFAs was accompanied by a decrease in soil labile organic C (microbial biomass carbon and dissolved organic carbon), and appeared to accelerate decomposition and reduce the stability of the soil C pool. Invertase and urease activity in shallow soils and acid-phosphatase activity in deep soils (15-30 cm depth) was inhibited by N additions. Together, these findings suggest that an increase in N deposition in peatlands could accelerate litter decomposition and the loss of labile C, as well as alter microbial biomass and function. (C) 2016 Elsevier B.V. All rights reserved.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Modelling impacts of atmospheric deposition and temperature on long-term DOC trends

Authors: Sawicka, K; Rowe, EC; Evans, CD; Monteith, DT; E I Vanguelova, DT; Wade, AJ; J M Clark, AJ (2017) Science of the Total Environment 578:323-336. HERO ID: 3546238

[Less] It is increasingly recognised that widespread and substantial increases in Dissolved organic carbon . . . [More] It is increasingly recognised that widespread and substantial increases in Dissolved organic carbon (DOC) concentrations in remote surface, and soil, waters in recent decades are linked to declining acid deposition. Effects of rising pH and declining ionic strength on DOC solubility have been proposed as potential dominant mechanisms. However, since DOC in these systems is derived mainly from recently-fixed carbon, and since organic matter decomposition rates are considered sensitive to temperature, uncertainty persists over the extent to which other drivers that could influence DOC production. Such potential drivers include fertilisation by nitrogen (N) and global warming. We therefore ran the dynamic soil chemistry model MADOC for a range of UK soils, for which time series data are available, to consider the likely relative importance of decreased deposition of sulphate and chloride, accumulation of reactive N, and higher temperatures, on soil DOC production in different soils. Modelled patterns of DOC change generally agreed favourably with measurements collated over 10-20years, but differed markedly between sites. While the acidifying effect of sulphur deposition appeared to be the predominant control on the observed soil water DOC trends in all the soils considered other than a blanket peat, the model suggested that over the long term, the effects of nitrogen deposition on N-limited soils may have been sufficient to raise the "acid recovery DOC baseline" significantly. In contrast, reductions in non-marine chloride deposition and effects of long term warming appeared to have been relatively unimportant. The suggestion that future DOC concentrations might exceed preindustrial levels as a consequence of nitrogen pollution has important implications for drinking water catchment management and the setting and pursuit of appropriate restoration targets, but findings still require validation from reliable centennial-scale proxy records, such as those being developed using palaeolimnological techniques.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Fungi exposed to chronic nitrogen enrichment are less able to decay leaf litter

Authors: van Diepen, LT; Frey, SD; Landis, EA; Morrison, EW; Pringle, A (2017) HERO ID: 3546917

[Less] Saprotrophic fungi are the primary decomposers of plant litter in temperate forests, and their activity . . . [More] Saprotrophic fungi are the primary decomposers of plant litter in temperate forests, and their activity is critical for carbon (C) and nitrogen (N) cycling. Simulated atmospheric N deposition is associated with reduced fungal biomass, shifts in fungal community structure, slowed litter decay, and soil C accumulation. Although rarely studied, N deposition may also result in novel selective pressures on fungi, affecting evolutionary trajectories. To directly test if long-term N enrichment reshapes fungal responses to N, we isolated decomposer fungi from a long-term (28 yr) N-addition experiment and used a common garden approach to compare growth rates and decay abilities of isolates from control and N-amended plots. Both growth and decay were significantly altered by long-term exposure to N enrichment. Changes in growth rates were idiosyncratic, as different species grew either more quickly or more slowly after exposure to N, but litter decay by N isolates was consistent and generally lower compared to control isolates of the same species, a response not readily reversed when N isolates were grown in control (low N) environments. Changes in fungal responses accompany and perhaps drive previously observed N-induced shifts in fungal diversity, community composition, and litter decay dynamics.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Dry deposition and canopy uptake in Mediterranean holm-oak forests estimated with a canopy budget model: A focus on N estimations

Authors: Aguillaume, L; Izquieta-Rojano, S; Garcia-Gomez, H; Elustondo, D; Santamaria, JM; Alonso, R; Avila, A (2017) Atmospheric Environment 152:191-200. HERO ID: 3844239

[Less] Bulk/wet and throughfall fluxes of major compounds were measured from June 2011 to June 2013 at four . . . [More] Bulk/wet and throughfall fluxes of major compounds were measured from June 2011 to June 2013 at four Mediterranean holm-oak (Quercus ilex) forests in the Iberian Peninsula. Regression analysis between net throughfall fluxes and precipitation indicated that the best defined canopy process was leaching for K+ and uptake for NH4+ at all sites. A more variable response between sites was found for Na+, Ca2+, SO42- and Cl-, which suggests that the interplay of dry deposition, leaching and uptake at the canopy was different depending on site climate and air quality characteristics.

A canopy budget model (CBM) was used to try to discriminate between the canopy processes and enable to estimate dry deposition and uptake fluxes at three of the sites that complied with the model specifications. To derive N uptake, an efficiency factor of NH4+ vs. NO3- uptake (xNH(4)) corresponding to moles of NH4+ taken up for each NO3- mol, has to be determined. Up to now, a value of 6 has been proposed for temperate forests, but we lack information for Mediterranean forests. Experimental determination of N absorption on Quercus ilex seedlings in Spain suggests efficiency factors from 1 to 6. Based on these values, a sensitivity analysis for xNH4 was performed and the NH4-N and NO3-N modeled dry deposition was compared with dry deposition estimated with independent methods (inferential modeling and washing of branches). At two sites in NE Spain under a milder Mediterranean climate, the best match was obtained for xNH(4) = 6, corroborating results from European temperate forests. Based on this value, total DIN deposition was 12-13 kg N ha(-1) y(-1) at these sites. However, for a site in central Spain under drier conditions, variation of the NH4+ efficiency factor had little effect on DD estimates (which ranged from 2 to 2.6 kg N ha(-1) y(-1) with varying xNH(4)); when added to wet deposition, this produced a total N deposition in the range 2.6-3.4 kg N ha(-1) y(-1). Dry deposition was the predominant pathway for N, accounting for 60-80% of total deposition, while for base cations wet deposition dominated (55-65%). Nitrogen deposition values at the northwestern sites were close to the empirical critical load proposed for evergreen sclerophyllous Mediterranean forests (15 -17 kg N ha(-1) y(-1)). When organic N deposition at these forests is added (3 kg N ha(-1) y(-1)), the total N input to the sites in NE Spain are close to the critical loads for Mediterranean evergreen oak forests. (C) 2016 Elsevier Ltd. All rights reserved.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Cross-biome assessment of gross soil nitrogen cycling in California ecosystems

Authors: Yang, WH; Ryals, RA; Cusack, DF; Silver, WL (2017) Soil Biology and Biochemistry 107:144-155. HERO ID: 3851222

[Less] Microbial transformations of nitrogen (N) largely determine whether N is retained in ecosystems via . . . [More] Microbial transformations of nitrogen (N) largely determine whether N is retained in ecosystems via net primary productivity or lost via gaseous emissions and leaching. The controls on soil N cycling are often studied at single locales, making it difficult to predict N cycling at regional to global scales. We hy-pothesized that contemporary soil properties exhibit consistent relationships with instantaneous gross N cycling rates across diverse biomes that create a continuum in these properties. We measured ex situ gross N cycling rates and soil properties at 33 study sites representing five biome classifications in California including deserts, grasslands, shrublands, forest, and wetlands. Desert soils had significantly lower total N, organic carbon (C), microbial biomass N, and soil moisture as well as higher pH than all other biomes, whereas forests and wetlands had significantly lower soil nitrate (NO3 (-)) concentrations (P < 0.001 for all). Gross mineralization rates were best predicted by the combination of soil moisture and soil C:N ratios (R-2 = 0.46), which exerted positive and negative controls, respectively. Grasslands exhibited marginally higher gross mineralization than all other biomes, whereas deserts had the lowest rates due to low soil moisture (P = 0.09). Gross nitrification rates were positively correlated to soil NO3 concentrations (R-2 = 0.34) and negatively correlated to soil C:N ratios (R2 = 0.31). The negative relationship between gross nitrification and soil C:N ratios was driven by forest soils, which had significantly higher C:N ratios and lower gross nitrification than all other biomes (P < 0.05). Dissimilatory NOy reduction to NH4- (DNRA) occurred in soils from all biomes. The strong positive correlation between DNRA rates and soil NO3- (R-2 = 0.41) suggests NO3- limitation of DNRA. Predictable patterns in gross N cycling across biomes in California suggest that contemporary soil properties are important drivers of instantaneous soil N cycling rates that integrate over differences in vegetation type, atmospheric N deposition rates, and local climate. (C) 2017 Elsevier Ltd. All rights reserved.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Addition of nitrogen enhances stability of soil organic matter in a temperate forest

Authors: Chen, ZJ; Geng, SC; Zhang, JH; Setälä, H; Gu, Y; Wang, F; Zhang, X; Wang, XX; Han, SJ (2017) European Journal of Soil Science 68:189-199. HERO ID: 3869726

[Less] Physicochemical protection of soil carbon provided by soil aggregates is critical to carbon (C) sequestration . . . [More] Physicochemical protection of soil carbon provided by soil aggregates is critical to carbon (C) sequestration in terrestrial ecosystems. However, the stability of soil organic matter (SOM) in terrestrial ecosystems in response to atmospheric nitrogen (N) deposition is unclear. In this study, N was added to a forest soil dominated by deciduous trees on Changbai Mountain, China, at three different rates (0, 25 and 50kgNha(-1)year(-1)) from 2007 to 2012. Its effect on C content and stabilization was evaluated by soil fractionation and stable isotope (C-13) analyses. The results showed that large macroaggregates (2-8mm) decreased and small macroaggregates (0.25-2mm) increased with increasing rates of N addition, whereas soil C content remained unchanged. Irrespective of the N treatments, the C content of soil organic matter (SOM) fractions differed significantly between large and small macroaggregates, which suggests that the size of aggregate classes regulates C content in the SOM fractions. A slight increase in the C content of microaggregates within macroaggregates (Mm) and that of silt and clay fractions was recorded with the addition of N at 50kgNha(-1)year(-1). This increase also occurred in the silt and clay fraction within microaggregates (Intra-SC). Unprotected C (comprising the free light fraction (Free-LF) and coarse particulate organic matter (CPOM)) accounted for 18.9% only of the total C and decreased in response to the addition of N. The C-13 signature and C/N ratios obtained for SOM fractions showed that newly formed C was transferred from POM to Intra-SC. Overall, our results suggested that long-term addition of N might promote stabilization of C by increasing small macro- and micro-aggregation within macroaggregates in temperate forest soil.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Simple additive simulation overestimates real influence: altered nitrogen and rainfall modulate the effect of warming on soil carbon fluxes

Authors: Ni, X; Yang, W; Qi, Z; Liao, S; Xu, Z; Tan, B; Wang, B; Wu, Q; Fu, C; You, C; Wu, F (2017) HERO ID: 3941213

[Less] Experiments and models have led to a consensus that there is positive feedback between carbon (C) fluxes . . . [More] Experiments and models have led to a consensus that there is positive feedback between carbon (C) fluxes and climate warming. However, the effect of warming may be altered by regional and global changes in nitrogen (N) and rainfall levels, but the current understanding is limited. Through synthesizing global data on soil C pool, input and loss from experiments simulating N deposition, drought and increased precipitation, we quantified the responses of soil C fluxes and equilibrium to the three single factors and their interactions with warming. We found that warming slightly increased the soil C input and loss by 5% and 9%, respectively, but had no significant effect on the soil C pool. Nitrogen deposition alone increased the soil C input (+20%), but the interaction of warming and N deposition greatly increased the soil C input by 49%. Drought alone decreased the soil C input by 17%, while the interaction of warming and drought decreased the soil C input to a greater extent (-22%). Increased precipitation stimulated the soil C input by 15%, but the interaction of warming and increased precipitation had no significant effect on the soil C input. However, the soil C loss was not significantly affected by any of the interactions, although it was constrained by drought (-18%). These results implied that the positive C fluxes-climate warming feedback was modulated by the changing N and rainfall regimes. Further, we found that the additive effects of [warming × N deposition] and [warming × drought] on the soil C input and of [warming × increased precipitation] on the soil C loss were greater than their interactions, suggesting that simple additive simulation using single-factor manipulations may overestimate the effects on soil C fluxes in the real world. Therefore, we propose that more multifactorial experiments should be considered in studying Earth systems.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Decomposition nitrogen is better retained than simulated deposition from mineral amendments in a temperate forest

Authors: Nair, RK; Perks, MP; Mencuccini, M (2017) HERO ID: 3941255

[Less] Nitrogen (N) deposition (NDEP ) drives forest carbon (C) sequestration but the size of this effect is . . . [More] Nitrogen (N) deposition (NDEP ) drives forest carbon (C) sequestration but the size of this effect is still uncertain. In the field, an estimate of these effects can be obtained by applying mineral N fertilizers over the soil or forest canopy. A (15) N label in the fertilizer can be then used to trace the movement of the added N into ecosystem pools and deduce a C effect. However, N recycling via litter decomposition provides most of the nutrition for trees, even under heavy NDEP inputs. If this recycled litter nitrogen is retained in ecosystem pools differently to added mineral N, then estimates of the effects of NDEP on the relative change in C (∆C/∆N) based on short-term isotope-labelled mineral fertilizer additions should be questioned. We used (15) N labelled litter to track decomposed N in the soil system (litter, soils, microbes, and roots) over 18 months in a Sitka spruce plantation and directly compared the fate of this (15) N to an equivalent amount in simulated NDEP treatments. By the end of the experiment, three times as much (15) N was retained in the O and A soil layers when N was derived from litter decomposition than from mineral N additions (60% and 20%, respectively), primarily because of increased recovery in the O layer. Roots expressed slightly more (15) N tracer from litter decomposition than from simulated mineral NDEP (7.5% and 4.5%) and compared to soil recovery, expressed proportionally more (15) N in the A layer than the O layer, potentially indicating uptake of organic N from decomposition. These results suggest effects of NDEP on forest ∆C/∆N may not be apparent from mineral (15) N tracer experiments alone. Given the importance of N recycling, an important but underestimated effect of NDEP is its influence on the rate of N release from litter.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Anthropogenic N deposition increases soil organic matter accumulation without altering its biochemical composition

Authors: Zak, DR; Freedman, ZB; Upchurch, RA; Steffens, M; Kögel-Knabner, I (2017) Global Change Biology 23:933-944. HERO ID: 3606034

[Less] Accumulating evidence indicates that future rates of atmospheric N deposition have the potential to . . . [More] Accumulating evidence indicates that future rates of atmospheric N deposition have the potential to increase soil C storage by reducing the decay of plant litter and soil organic matter (SOM). Although the microbial mechanism underlying this response is not well understood, a decline in decay could alter the amount, as well as biochemical composition of SOM. Here, we used size-density fractionation and solid-state (13) C-NMR spectroscopy to explore the extent to which declines in microbial decay in a long-term (ca. 20 yrs.) N deposition experiment have altered the biochemical composition of forest floor, bulk mineral soil, as well as free and occluded particulate organic matter. Significant amounts of organic matter have accumulated in occluded particulate organic matter (~20%; oPOM); however, experimental N deposition had not altered the abundance of carboxyl, aryl, alkyl, or O/N-alkyl C in forest floor, bulk mineral soil, or any soil fraction. These observations suggest that biochemically equivalent organic matter has accumulated in oPOM at a greater rate under experimental N deposition, relative to the ambient treatment. Although we do not understand the process by which experimental N deposition has fostered the occlusion of organic matter by mineral soil particles, our results highlight the importance of interactions among the products of microbial decay and the chemical and physical properties of silt and clay particles that occlude organic matter from microbial attack. Because oPOM can reside in soils for decades to centuries, organic matter accumulating under future rates of anthropogenic N deposition could remain in soil for long periods of time. If temperate forest soils in the Northern Hemisphere respond like those in our experiment, then unabated deposition of anthropogenic N from the atmosphere has the potential to foster greater soil C storage, especially in fine-texture forest soils.