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Kopáček J, Bače R, Choma M, Hejzlar J, Kaňa J, Oulehle F, Porcal P, Svoboda M, Tahovská K. Carbon and nutrient pools and fluxes in unmanaged mountain Norway spruce forests, and losses after natural tree dieback. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 903:166233. [PMID: 37572919 DOI: 10.1016/j.scitotenv.2023.166233] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2023] [Revised: 08/02/2023] [Accepted: 08/09/2023] [Indexed: 08/14/2023]
Abstract
Forest areas infected by insects are increasing in Europe and North America due to accelerating climate change. A 2000-2020 mass budget study on major elements (C, N, P, Ca, Mg, K) in the atmosphere-plant-soil-water systems of two unmanaged catchments enabled us to evaluate changes in pools and fluxes related to tree dieback and long-term accumulation/losses during the post-glacial period. A bark-beetle outbreak killed >75 % of all trees in a mature mountain spruce forest in one catchment and all dead biomass was left on site. A similar forest in a nearby catchment was only marginally affected. We observed that: (1) the long-term (millennial) C and N accumulation in soils averaged 10-22 and 0.5-1.1 kg ha-1 yr-1, respectively, while losses of Ca, Mg, and K from soils ranged from 0.1 to 2.6 kg ha-1 yr-1. (2) Only <0.8 % and <1.5 % of the respective total C and N fluxes entering the soil annually from vegetation were permanently stored in soils. (3) The post-disturbance decomposition of dead tree biomass reduced vegetation element pools from 27 % (C) to 73 % (P) between 2004 and 2019. (4) Tree dieback decreased net atmospheric element inputs to the impacted catchment, and increased the leaching of all elements and gaseous losses of C (∼2.3 t ha-1 yr-1) and N (∼14 kg ha-1 yr-1). The disturbed catchment became a net C source, but ∼50 % of the N released from dead biomass accumulated in soils. (5) Despite the severe forest disturbance, the dissolved losses of Ca and Mg represented 52-58 % of their leaching from intact stands during the peaking atmospheric acidification from 1970 to 1990. (6) Disturbance-related net leaching of P, Ca, Mg, and K were 4, 69, 16, and 114 kg ha-1, respectively, which represented 7-38 % of the losses potentially related to sanitary logging and subsequent removal of the aboveground tree biomass.
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Affiliation(s)
- Jiří Kopáček
- Biology Centre CAS, Institute of Hydrobiology, České Budějovice, Czech Republic; University of South Bohemia, Faculty of Science, České Budějovice, Czech Republic.
| | - Radek Bače
- Czech University of Life Sciences, Faculty of Forestry and Wood Science, Prague, Czech Republic
| | - Michal Choma
- University of South Bohemia, Faculty of Science, České Budějovice, Czech Republic
| | - Josef Hejzlar
- Biology Centre CAS, Institute of Hydrobiology, České Budějovice, Czech Republic
| | - Jiří Kaňa
- Biology Centre CAS, Institute of Hydrobiology, České Budějovice, Czech Republic; University of South Bohemia, Faculty of Science, České Budějovice, Czech Republic
| | - Filip Oulehle
- Czech Geological Survey, Klárov 3, 11821 Prague 1, Czech Republic
| | - Petr Porcal
- Biology Centre CAS, Institute of Hydrobiology, České Budějovice, Czech Republic; University of South Bohemia, Faculty of Science, České Budějovice, Czech Republic
| | - Miroslav Svoboda
- Czech University of Life Sciences, Faculty of Forestry and Wood Science, Prague, Czech Republic
| | - Karolina Tahovská
- University of South Bohemia, Faculty of Science, České Budějovice, Czech Republic
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Wessel WW, Boxman AW, Cerli C, van Loon EE, Tietema A. Long-term stabilization of 15N-labeled experimental NH 4+ deposition in a temperate forest under high N deposition. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 768:144356. [PMID: 33453534 DOI: 10.1016/j.scitotenv.2020.144356] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Revised: 11/30/2020] [Accepted: 12/01/2020] [Indexed: 06/12/2023]
Abstract
High nitrogen (N) deposition levels, currently present in many industrial and agricultural regions of the world, can strongly affect the functioning of forest ecosystems. In a pine forest with strong N leaching, located in the Netherlands, we studied the long-term fate of a year-long NH4+ deposition cohort labeled with 15N. A high ambient and a low N deposition treatment had been established at the site by means of a roof and sprinklers. Resampling the N pools 19 years after labeling and 11 years after the last sampling, we found similar 15N deltas in needles, twigs and the LF1 organic soil layer of each treatment, indicating intensive N cycling among these pools. In the last 11 years, label recovery decreased in these labile pools, while recovery remained constant in wood and increased in bark. Together these aboveground vegetation pools retained less than 3% of the labeled N. In the organic layers, label recovery after 19 years decreased to 23% in both treatments, while in the mineral soil it increased from 4% to 13% (high N) and from 3% to 29% (low N treatment). Within the mineral soil of the high N treatment the labeled N was mainly found in fine roots, while in the low N treatment most N was incorporated in the two soil density fractions, shifting to the high density fraction with depth. This suggests a low capacity of the mineral soil at high N deposition to incorporate N. After the labeled N had been lost substantially in previous years, especially in the first, its presence remained constant in the last 11 years at 38% (high N) and 54% (low N treatment). Apparently, even in this strongly N leaching ecosystem, N once incorporated, was retained well and did not affect the input-output fluxes of the system.
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Affiliation(s)
- Wim W Wessel
- Institute for Biodiversity and Ecosystem Dynamics (IBED), University of Amsterdam, P.O.Box 90240, 1090 GE Amsterdam, the Netherlands.
| | - Andries W Boxman
- Department of Aquatic Ecology and Environmental Biology, Radboud University Nijmegen, P.O.Box 9010, 6500 GL Nijmegen, the Netherlands.
| | - Chiara Cerli
- Institute for Biodiversity and Ecosystem Dynamics (IBED), University of Amsterdam, P.O.Box 90240, 1090 GE Amsterdam, the Netherlands.
| | - E Emiel van Loon
- Institute for Biodiversity and Ecosystem Dynamics (IBED), University of Amsterdam, P.O.Box 90240, 1090 GE Amsterdam, the Netherlands.
| | - Albert Tietema
- Institute for Biodiversity and Ecosystem Dynamics (IBED), University of Amsterdam, P.O.Box 90240, 1090 GE Amsterdam, the Netherlands.
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Yang P, Wang Y, Wu X, Chang L, Ham B, Song L, Groves C. Nitrate sources and biogeochemical processes in karst underground rivers impacted by different anthropogenic input characteristics. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2020; 265:114835. [PMID: 32540593 DOI: 10.1016/j.envpol.2020.114835] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Revised: 05/08/2020] [Accepted: 05/16/2020] [Indexed: 06/11/2023]
Abstract
Nitrate is one of the most common pollution sources in groundwater, particularly in highly vulnerable karst aquifers. The potential for nitrification and denitrification within karst aquifers varies in different settings depending on the extent of anthropogenic inputs, so that accurate identification of nitrate sources can be difficult. Geochemical data and dual nitrate isotopes were measured in this study, incorporating a Bayesian isotopic mixing model, and used to identify nitrate sources, nitrification and denitrification, and quantitatively determine nitrate sources under different extents of anthropogenic inputs in three karst catchments within Chongqing Municipality, SW China: Laolongdong (an urbanized area), Qingmuguan (a suburban village), and Shuifang Spring (a protected natural area). At the Laolongdong catchment, the groundwater was in a reducing condition and enriched in δ15NNO3 (averaging 18.9 ± 6.9‰) and δ18ONO3 (averaging 8.5 ± 4.6‰). Manure and sewage waste were the main contributing nitrate sources. A slope of 1.8: 1 of the dual isotopes suggested a denitrification process occurring in anaerobic conduit flow. Within the Qingmuguan catchment, groundwater had average δ15NNO3 and δ18ONO3 values of 9.7 ± 3.5‰, and 1.9 ± 3.4‰, respectively. The data showed evidence for nitrification, and the contribution of soil organic nitrogen was 52.1%, followed by a contribution of 44.8% from manure and wastewater. At the Shuifang Spring catchment, the mean δ15NNO3 and δ18ONO3 values in groundwater were 8.8 ± 2.9‰, 2.3 ± 4.6‰, respectively. Nitrification was the dominant process and most of the nitrate was derived from soil organic nitrogen. This study suggests that karst underground rivers overlain by urban land use undergo denitrification, while the suburban and relatively pristine karst aquifers are dominated by nitrification, allowing development of a conceptual model for nitrate sources and transformations in karst aquifers from the categories of land use (i.e., urban, suburban, and pristine areas). MAIN FINDING: Anthropogenic activities can change biogeochemical nitrogen dynamics of vulnerable karst aquifers, such that the groundwater overlain by an urban settlement has undergone denitrification, while suburban and pristine areas have been dominated by nitrification.
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Affiliation(s)
- Pingheng Yang
- State Cultivation Base of Eco-agriculture for Southwest Mountainous Land, Field Scientific Observation & Research Base of Karst Eco-environments at Nanchuan in Chongqing, Ministry of Natural Resources, School of Geographical Sciences, Southwest University, Chongqing, 400715, China; Crawford Hydrology Laboratory, Department of Geography and Geology, Western Kentucky University, Bowling Green, KY, 42101, USA.
| | - Yuyang Wang
- State Cultivation Base of Eco-agriculture for Southwest Mountainous Land, Field Scientific Observation & Research Base of Karst Eco-environments at Nanchuan in Chongqing, Ministry of Natural Resources, School of Geographical Sciences, Southwest University, Chongqing, 400715, China
| | - Xinyu Wu
- Southwest University Library, Chongqing, 400715, China
| | - Longran Chang
- College of Resources and Environment, Southwest University, Chongqing, 400715, China
| | - Brian Ham
- Tennessee Department of Environment and Conservation, Division of Water Resources, Nashville, TN, 37243, USA
| | - Lisheng Song
- State Cultivation Base of Eco-agriculture for Southwest Mountainous Land, Field Scientific Observation & Research Base of Karst Eco-environments at Nanchuan in Chongqing, Ministry of Natural Resources, School of Geographical Sciences, Southwest University, Chongqing, 400715, China
| | - Chris Groves
- Crawford Hydrology Laboratory, Department of Geography and Geology, Western Kentucky University, Bowling Green, KY, 42101, USA; UNESCO Mammoth Cave Area Biosphere Reserve, Mammoth Cave, KY, 42259, USA
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Britton AJ, Gibbs S, Fisher JM, Helliwell RC. Impacts of nitrogen deposition on carbon and nitrogen cycling in alpine Racomitrium heath in the UK and prospects for recovery. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2019; 254:112986. [PMID: 31394340 DOI: 10.1016/j.envpol.2019.112986] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Revised: 07/24/2019] [Accepted: 07/30/2019] [Indexed: 06/10/2023]
Abstract
Deposition of reactive nitrogen (N) is a major threat to terrestrial ecosystems associated with impacts on ecosystem properties and functions including carbon (C) and nutrient stocks, soil water quality and nutrient retention. In the oceanic-alpine Racomitrium heath habitat, N deposition is associated with moss mat degradation and a shift from bryophyte to graminoid dominance. To investigate the effects of moss mat decline on C and N stocks and fluxes, we collected Racomitrium heath vegetation/soil cores from sites along a gradient of N deposition in the UK. Cores were maintained under controlled conditions and exposed to scenarios of current (8-40 kg N ha-1 y-1), reduced (8 kg N ha-1 y-1) and elevated (50 kg N ha-1 y-1) N deposition. Cores from high N deposition sites had smaller aboveground C and N stocks and, under current conditions, leached large amounts of inorganic N and had low soil water pH compared with low N deposition sites. With reduced N deposition there was evidence for rapid recovery of soil water quality in terms of reduced N leaching and small increases in pH. Under high N deposition, cores from low N deposition sites retained much of the applied N while those with a history of high N deposition leached large amounts of inorganic N. Carbon fluxes in soil water and net CO2 fluxes varied according to core source site but were not affected by the N deposition scenarios. We conclude that C and N stocks and cycling in Racomitrium heath are strongly affected by long-term exposure to N deposition but that soil water quality may improve rapidly, if N deposition rates are reduced. The legacy of N deposition impacts on moss mat cover and vegetation composition however, mean that the ecosystem remains sensitive to future pulses in N input.
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Affiliation(s)
- Andrea J Britton
- The James Hutton Institute, Craigiebuckler, Aberdeen, AB15 8QH, UK.
| | - Sheila Gibbs
- The James Hutton Institute, Craigiebuckler, Aberdeen, AB15 8QH, UK
| | - Julia M Fisher
- The James Hutton Institute, Craigiebuckler, Aberdeen, AB15 8QH, UK
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Harrison S, McAree C, Mulville W, Sullivan T. The problem of agricultural 'diffuse' pollution: Getting to the point. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 677:700-717. [PMID: 31071672 DOI: 10.1016/j.scitotenv.2019.04.169] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Revised: 04/10/2019] [Accepted: 04/11/2019] [Indexed: 06/09/2023]
Abstract
Despite introduction of legislation such as the EU Nitrates and Water Framework Directives (Directives 91/676/EEC and 2000/60/EC respectively), agricultural practices are often still regarded as a major factor in poor water quality across many EU member states. Elevated inputs of nutrients, organic matter and agro-chemicals to receiving waters from agricultural lands in particular are now widely recognised as potentially major causes of deteriorating water quality. Such inputs may emanate from diffuse sources such as agricultural fields, and small point- or intermediate-sources, including farmyards and farm trackways. However, while inputs from these latter intermediate sources may be substantial, their overall contribution to catchment-wide water quality at high temporal or spatial resolution is still largely unknown. In this study, we surveyed water chemistry throughout the multiple natural and artificial watercourses within a single drainage network at high spatial resolution in a predominantly dairy farming area in Southern Ireland. We found that most headwaters at the time of study were impacted by organic inputs via drainage ditches emanating from the vicinity of farmyards. These farmyard drains were found to have elevated concentrations of ammonium, phosphorus, potassium, suspended sediment and biochemical oxygen demand above background levels in the study catchment. Concomitant assessment of macro-invertebrate communities at study sites indicated that the ecological quality of headwaters was also impaired by these inputs. The individual and aggregate contributions of farmyard drains to water quality within a single catchment, when mapped at high spatial resolution, indicates that they constitute a major contribution to catchment scale 'diffuse' agricultural inputs. However, our data also suggest that engineering farmyard drains to maximise their retention and attenuation function may prove to be a cost-effective means of mitigating the effects of point source farmyard inputs.
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Affiliation(s)
- Simon Harrison
- School of Biological, Earth and Environmental Sciences, University College Cork, Ireland.
| | - Cassandra McAree
- School of Biological, Earth and Environmental Sciences, University College Cork, Ireland
| | - William Mulville
- School of Biological, Earth and Environmental Sciences, University College Cork, Ireland
| | - Timothy Sullivan
- School of Biological, Earth and Environmental Sciences, University College Cork, Ireland
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Jacquemin C, Bertrand C, Franquet E, Mounier S, Misson B, Oursel B, Cavalli L. Effects of catchment area and nutrient deposition regime on phytoplankton functionality in alpine lakes. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 674:114-127. [PMID: 31004889 DOI: 10.1016/j.scitotenv.2019.04.117] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Revised: 03/11/2019] [Accepted: 04/09/2019] [Indexed: 06/09/2023]
Abstract
High mountain lakes are a network of sentinels, sensitive to any events occurring within their waterbodies, their surrounding catchment and their airshed. In this paper, we investigate how catchments impact the taxonomic and functional composition of phytoplankton communities in high mountain lakes, and how this impact varies according to the atmospheric nutrient deposition regime. For two years, we sampled the post snow-melt and the late summer phytoplankton, with a set of biotic and abiotic parameters, in six French alpine lakes with differing catchments (size and vegetation cover) and contrasting nitrogen (N) and phosphorus (P) deposition regimes. Whatever the nutrient deposition regime, we found that the lakes with the smallest rocky catchments showed the lowest functional richness of phytoplankton communities. The lakes with larger vegetated catchments were characterized by the coexistence of phytoplankton taxa with more diverse strategies in the acquisition and utilization of nutrient resources. The nutrient deposition regime appeared to interact with catchment characteristics in determining which functional groups ultimately developed in lakes. Photoautotroph taxa dominated the phytoplankton assemblages under high NP deposition regime while mixotroph taxa were even more favored in lakes with large vegetated catchments under low NP deposition regime. Phytoplankton functional changes were likely related to the leaching of terrestrial organic matter from catchments evidenced by analyses of carbon (δ13C) and nitrogen (δ15N) stable isotope ratios in seston and zooplankton. Plankton δ15N values indicated greater water-soil interaction in lakes with larger vegetated catchments, while δ13C values indicated the effective mineralization of the organic matter in lakes. The role played by catchments should be considered when seeking to determine the vulnerability of high altitude lakes to future changes, as catchments' own properties will vary under changes related to climate and airborne contaminants.
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Affiliation(s)
- Coralie Jacquemin
- Aix Marseille Univ, Univ Avignon, CNRS, IRD, IMBE, Marseille, France.
| | - Céline Bertrand
- Aix Marseille Univ, Univ Avignon, CNRS, IRD, IMBE, Marseille, France.
| | - Evelyne Franquet
- Aix Marseille Univ, Univ Avignon, CNRS, IRD, IMBE, Marseille, France.
| | - Stéphane Mounier
- Aix Marseille Univ., Université de Toulon, CNRS, IRD, MIO UM 110, 13288, Marseille, France.
| | - Benjamin Misson
- Aix Marseille Univ., Université de Toulon, CNRS, IRD, MIO UM 110, 13288, Marseille, France.
| | - Benjamin Oursel
- Aix Marseille Univ, Univ Avignon, CNRS, IRD, IMBE, Marseille, France.
| | - Laurent Cavalli
- Aix Marseille Univ, Univ Avignon, CNRS, IRD, IMBE, Marseille, France.
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Yu L, Mulder J, Zhu J, Zhang X, Wang Z, Dörsch P. Denitrification as a major regional nitrogen sink in subtropical forest catchments: Evidence from multi-site dual nitrate isotopes. GLOBAL CHANGE BIOLOGY 2019; 25:1765-1778. [PMID: 30776171 DOI: 10.1111/gcb.14596] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Accepted: 01/29/2019] [Indexed: 06/09/2023]
Abstract
Increasing nitrogen (N) deposition in subtropical forests in south China causes N saturation, associated with significant nitrate (NO3- ) leaching. Strong N attenuation may occur in groundwater discharge zones hydrologically connected to well-drained hillslopes, as has been shown for the subtropical headwater catchment "TieShanPing", where dual NO3- isotopes indicated that groundwater discharge zones act as an important N sink and hotspot for denitrification. Here, we present a regional study reporting inorganic N fluxes over two years together with dual NO3- isotope signatures obtained in two summer campaigns from seven forested catchments in China, representing a gradient in climate and atmospheric N input. In all catchments, fluxes of dissolved inorganic N indicated efficient conversion of NH4+ to NO3- on well-drained hillslopes, and subsequent interflow of NO3- over the argic B-horizons to groundwater discharge zones. Depletion of 15 N- and 18 O-NO3- on hillslopes suggested nitrification as the main source of NO3- . In all catchments, except one of the northern sites, which had low N deposition rates, NO3- attenuation by denitrification occurred in groundwater discharge zones, as indicated by simultaneous 15 N and 18 O enrichment in residual NO3- . By contrast to the southern sites, the northern catchments lack continuous and well-developed groundwater discharge zones, explaining less efficient N removal. Using a model based on 15 NO3- signatures, we estimated denitrification fluxes from 2.4 to 21.7 kg N ha-1 year-1 for the southern sites, accounting for more than half of the observed N removal. Across the southern catchments, estimated denitrification scaled proportionally with N deposition. Together, this indicates that N removal by denitrification is an important component of the N budget of southern Chinese forests and that natural NO3- attenuation may increase with increasing N input, thus partly counteracting further aggravation of N contamination of surface waters in the region.
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Affiliation(s)
- Longfei Yu
- Faculty of Environmental Sciences and Natural Resource Management, Norwegian University of Life Sciences, Aas, Norway
| | - Jan Mulder
- Faculty of Environmental Sciences and Natural Resource Management, Norwegian University of Life Sciences, Aas, Norway
| | - Jing Zhu
- Faculty of Environmental Sciences and Natural Resource Management, Norwegian University of Life Sciences, Aas, Norway
- Department of Environment and Resources, Guangxi Normal University, Guilin, China
| | - Xiaoshan Zhang
- Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, China
| | - Zhangwei Wang
- Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, China
| | - Peter Dörsch
- Faculty of Environmental Sciences and Natural Resource Management, Norwegian University of Life Sciences, Aas, Norway
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Sebestyen SD, Ross DS, Shanley JB, Elliott EM, Kendall C, Campbell JL, Dail DB, Fernandez IJ, Goodale CL, Lawrence GB, Lovett GM, McHale PJ, Mitchell MJ, Nelson SJ, Shattuck MD, Wickman TR, Barnes RT, Bostic JT, Buda AR, Burns DA, Eshleman KN, Finlay JC, Nelson DM, Ohte N, Pardo LH, Rose LA, Sabo RD, Schiff SL, Spoelstra J, Williard KWJ. Unprocessed Atmospheric Nitrate in Waters of the Northern Forest Region in the U.S. and Canada. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:3620-3633. [PMID: 30830765 DOI: 10.1021/acs.est.9b01276] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Little is known about the regional extent and variability of nitrate from atmospheric deposition that is transported to streams without biological processing in forests. We measured water chemistry and isotopic tracers (δ18O and δ15N) of nitrate sources across the Northern Forest Region of the U.S. and Canada and reanalyzed data from other studies to determine when, where, and how unprocessed atmospheric nitrate was transported in catchments. These inputs were more widespread and numerous than commonly recognized, but with high spatial and temporal variability. Only 6 of 32 streams had high fractions (>20%) of unprocessed atmospheric nitrate during baseflow. Seventeen had high fractions during stormflow or snowmelt, which corresponded to large fractions in near-surface soil waters or groundwaters, but not deep groundwater. The remaining 10 streams occasionally had some (<20%) unprocessed atmospheric nitrate during stormflow or baseflow. Large, sporadic events may continue to be cryptic due to atmospheric deposition variation among storms and a near complete lack of monitoring for these events. A general lack of observance may bias perceptions of occurrence; sustained monitoring of chronic nitrogen pollution effects on forests with nitrate source apportionments may offer insights needed to advance the science as well as assess regulatory and management schemes.
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Affiliation(s)
- Stephen D Sebestyen
- USDA Forest Service , Northern Research Station , 1831 Highway 169 E , Grand Rapids , Minnesota 55744-3399 , United States
| | - Donald S Ross
- University of Vermont , Dept. of Plant and Soil Science , Burlington , Vermont 05405-1737 , United States
| | - James B Shanley
- U.S. Geological Survey (USGS) , New England Water Science Center , Montpelier , Vermont 05602 , United States
| | - Emily M Elliott
- University of Pittsburgh , Dept. of Geology and Environmental Science , Pittsburgh , Pennsylvania 15260-3332 , United States
| | - Carol Kendall
- USGS , Menlo Park , California 94025 , United States
| | - John L Campbell
- USDA Forest Service , Northern Research Station , Durham , New Hampshire 03824 , United States
| | - D Bryan Dail
- University of Maine , Department of Plant, Soil, and Environmental Science , Orono , Maine 04469 , United States
| | - Ivan J Fernandez
- University of Maine , School of Forest Resources , Orono , Maine 04469 , United States
| | - Christine L Goodale
- Cornell University , Ecology and Evolutionary Biology , Ithaca , New York 14850 , United States
| | | | - Gary M Lovett
- Cary Institute of Ecosystem Studies , Millbrook , New York 12545 , United States
| | - Patrick J McHale
- State University of New York College of Environmental Science and Forestry , Department of Environmental and Forest Biology , Syracuse , New York 13210 , United States
| | - Myron J Mitchell
- State University of New York College of Environmental Science and Forestry , Department of Environmental and Forest Biology , Syracuse , New York 13210 , United States
| | - Sarah J Nelson
- University of Maine , School of Forest Resources , Orono , Maine 04469 , United States
| | - Michelle D Shattuck
- University of New Hampshire , Dept. of Natural Resources and the Environment , Durham , New Hampshire 03824 , United States
| | - Trent R Wickman
- USDA Forest Service , National Forest System - Eastern Region , Duluth , Minnesota 55808 , United States
| | - Rebecca T Barnes
- Colorado College , Environmental Program , Colorado Springs , Colorado 80903 , United States
| | - Joel T Bostic
- University of Maryland Center for Environmental Science , Appalachian Laboratory , Frostburg , Maryland 21532 , United States
| | - Anthony R Buda
- USDA Agricultural Research Service , Pasture Systems and Watershed Management Research Unit , University Park , Pennsylvania 16802-3702 , United States
| | - Douglas A Burns
- USGS , NY Water Science Center , Troy , New York 12180 , United States
| | - Keith N Eshleman
- University of Maryland Center for Environmental Science , Appalachian Laboratory , Frostburg , Maryland 21532 , United States
| | - Jacques C Finlay
- University of Minnesota , Ecology, Evolution, and Behavior , St. Paul , Minnesota 55108 , United States
| | - David M Nelson
- University of Maryland Center for Environmental Science , Appalachian Laboratory , Frostburg , Maryland 21532 , United States
| | - Nobuhito Ohte
- Kyoto University , Department of Social Informatics , Kyoto , Kyoto Prefecture 6068501 , Japan
| | - Linda H Pardo
- USDA Forest Service , Northern Research Station , Burlington , Vermont 05405 , United States
| | - Lucy A Rose
- University of Minnesota , Department of Forest Resources , St. Paul , Minnesota 55108 , United States
| | - Robert D Sabo
- USDA Forest Service , Northern Research Station , Burlington , Vermont 05405 , United States
| | - Sherry L Schiff
- University of Waterloo , Department of Earth and Environmental Sciences , Waterloo , Ontario N2L 3G1 , Canada
| | - John Spoelstra
- Environment and Climate Change Canada , Canada Center for Inland Waters , Burlington , Ontario L7S 1A1 , Canada
| | - Karl W J Williard
- Southern Illinois University , Forestry Center for Ecology , Carbondale , Illinois 62901 , United States
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Fuss CB, Lovett GM, Goodale CL, Ollinger SV, Lang AK, Ouimette AP. Retention of Nitrate-N in Mineral Soil Organic Matter in Different Forest Age Classes. Ecosystems 2019. [DOI: 10.1007/s10021-018-0328-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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10
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Britton AJ, Mitchell RJ, Fisher JM, Riach DJ, Taylor AFS. Nitrogen deposition drives loss of moss cover in alpine moss-sedge heath via lowered C : N ratio and accelerated decomposition. THE NEW PHYTOLOGIST 2018; 218:470-478. [PMID: 29397029 DOI: 10.1111/nph.15006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Accepted: 12/20/2017] [Indexed: 06/07/2023]
Abstract
In alpine ecosystems, nitrogen (N) deposition has been linked to plant community composition change, including loss of bryophytes and increase of graminoids. Since bryophyte growth is stimulated by increased N availability, it has been hypothesized that loss of bryophyte cover is driven by enhanced decomposition. As bryophyte mats are a significant carbon (C) store, their loss may impact C storage in these ecosystems. We used an N deposition gradient across 15 sites in the UK to examine effects of N deposition on bryophyte litter quality, decomposition and C and N stocks in Racomitrium moss-sedge heath. Increasing N deposition reduced C : N in bryophyte litter, which in turn enhanced decomposition. Soil N stocks increased significantly in response to increased N deposition, and soil C : N declined. However, depletion of the bryophyte mat and its replacement by graminoids under high N deposition was not associated with a change in total ecosystem C stocks. We conclude that decomposition processes in Racomitrium heath are very sensitive to N deposition and provide a mechanism by which N deposition drives depletion of the bryophyte mat. Nitrogen deposition did not measurably alter C stocks, but changes in soil N stocks and C : N suggest the ecosystem is becoming N saturated.
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Affiliation(s)
- Andrea J Britton
- The James Hutton Institute, Craigiebuckler, Aberdeen, AB15 8QH, UK
| | - Ruth J Mitchell
- The James Hutton Institute, Craigiebuckler, Aberdeen, AB15 8QH, UK
| | - Julia M Fisher
- The James Hutton Institute, Craigiebuckler, Aberdeen, AB15 8QH, UK
| | - David J Riach
- The James Hutton Institute, Craigiebuckler, Aberdeen, AB15 8QH, UK
| | - Andy F S Taylor
- The James Hutton Institute, Craigiebuckler, Aberdeen, AB15 8QH, UK
- Institute of Biological and Environmental Sciences, University of Aberdeen, Cruickshank Building, Aberdeen, AB24 3UU, UK
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11
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Goodale CL. Multiyear fate of a 15 N tracer in a mixed deciduous forest: retention, redistribution, and differences by mycorrhizal association. GLOBAL CHANGE BIOLOGY 2017; 23:867-880. [PMID: 27564989 DOI: 10.1111/gcb.13483] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Revised: 07/11/2016] [Accepted: 07/25/2016] [Indexed: 05/11/2023]
Abstract
The impact of atmospheric nitrogen deposition on forest ecosystems depends in large part on its fate. Past tracer studies show that litter and soils dominate the short-term fate of added 15 N, yet few have examined its longer term dynamics or differences among forest types. This study examined the fate of a 15 N-NO3- tracer over 5-6 years in a mixed deciduous stand that was evenly composed of trees with ectomycorrhizal and arbuscular mycorrhizal associations. The tracer was expected to slowly mineralize from its main initial fate in litter and surface soil, with some 15 N moving to trees, some to deeper soil, and some net losses. Recovery of added 15 N in trees and litterfall totaled 11.3% both 1 and 5-6 years after the tracer addition, as 15 N redistributed from fine and especially coarse roots into cumulative litterfall and small accumulations in woody tissues. Estimates of potential carbon sequestration from tree 15 N recovery amounted to 12-14 kg C per kg of N deposition. Tree 15 N acquisition occurred within the first year after the tracer addition, with no subsequent additional net transfer of 15 N from detrital to plant pools. In both years, ectomycorrhizal trees gained 50% more of the tracer than did trees with arbuscular mycorrhizae. Much of the 15 N recovered in wood occurred in tree rings formed prior to the 15 N addition, demonstrating the mobility of N in wood. Tracer recovery rapidly decreased over time in surface litter material and accumulated in both shallow and deep soil, perhaps through mixing by earthworms. Overall, results showed redistribution of tracer 15 N through trees and surface soils without any losses, as whole-ecosystem recovery remained constant between 1 and 5-6 years at 70% of the 15 N addition. These results demonstrate the persistent ecosystem retention of N deposition even as it redistributes, without additional plant uptake over this timescale.
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Affiliation(s)
- Christine L Goodale
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY, 14853, USA
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12
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Catchment-Scale Modeling of Nitrogen Dynamics in a Temperate Forested Watershed, Oregon. An Interdisciplinary Communication Strategy. WATER 2015. [DOI: 10.3390/w7105345] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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13
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Wexler SK, Goodale CL, McGuire KJ, Bailey SW, Groffman PM. Isotopic signals of summer denitrification in a northern hardwood forested catchment. Proc Natl Acad Sci U S A 2014; 111:16413-8. [PMID: 25368188 PMCID: PMC4246341 DOI: 10.1073/pnas.1404321111] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Despite decades of measurements, the nitrogen balance of temperate forest catchments remains poorly understood. Atmospheric nitrogen deposition often greatly exceeds streamwater nitrogen losses; the fate of the remaining nitrogen is highly uncertain. Gaseous losses of nitrogen to denitrification are especially poorly documented and are often ignored. Here, we provide isotopic evidence (δ(15)NNO3 and δ(18)ONO3) from shallow groundwater at the Hubbard Brook Experimental Forest indicating extensive denitrification during midsummer, when transient, perched patches of saturation developed in hillslopes, with poor hydrological connectivity to the stream, while streamwater showed no isotopic evidence of denitrification. During small rain events, precipitation directly contributed up to 34% of streamwater nitrate, which was otherwise produced by nitrification. Together, these measurements reveal the importance of denitrification in hydrologically disconnected patches of shallow groundwater during midsummer as largely overlooked control points for nitrogen loss from temperate forest catchments.
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Affiliation(s)
- Sarah K Wexler
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY 14853; School of Environmental Sciences, University of East Anglia, Norwich NR4 7TJ, United Kingdom;
| | - Christine L Goodale
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY 14853;
| | - Kevin J McGuire
- Department of Forest Resources and Environmental Conservation, Virginia Water Resources Research Center, Virginia Tech, Blacksburg, VA 24061
| | - Scott W Bailey
- US Forest Service, Northern Research Station, North Woodstock, NH 03262; and
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14
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Homyak PM, Sickman JO, Miller AE, Melack JM, Meixner T, Schimel JP. Assessing Nitrogen-Saturation in a Seasonally Dry Chaparral Watershed: Limitations of Traditional Indicators of N-Saturation. Ecosystems 2014. [DOI: 10.1007/s10021-014-9792-2] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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15
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Hale RL, Turnbull L, Earl S, Grimm N, Riha K, Michalski G, Lohse KA, Childers D. Sources and transport of nitrogen in arid urban watersheds. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2014; 48:6211-6219. [PMID: 24803360 DOI: 10.1021/es501039t] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Urban watersheds are often sources of nitrogen (N) to downstream systems, contributing to poor water quality. However, it is unknown which components (e.g., land cover and stormwater infrastructure type) of urban watersheds contribute to N export and which may be sites of retention. In this study we investigated which watershed characteristics control N sourcing, biogeochemical processing of nitrate (NO3-) during storms, and the amount of rainfall N that is retained within urban watersheds. We used triple isotopes of NO3- (δ15N, δ18O, and Δ17O) to identify sources and transformations of NO3- during storms from 10 nested arid urban watersheds that varied in stormwater infrastructure type and drainage area. Stormwater infrastructure and land cover--retention basins, pipes, and grass cover--dictated the sourcing of NO3- in runoff. Urban watersheds were strong sinks or sources of N to stormwater depending on runoff, which in turn was inversely related to retention basin density and positively related to imperviousness and precipitation. Our results suggest that watershed characteristics control the sources and transport of inorganic N in urban stormwater but that retention of inorganic N at the time scale of individual runoff events is controlled by hydrologic, rather than biogeochemical, mechanisms.
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Affiliation(s)
- Rebecca L Hale
- School of Life Sciences, §Global Institute of Sustainability, and ◆School of Sustainability, Arizona State University , Tempe, Arizona 85287, United States
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16
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Long-Term Trends in Tree-Ring Width and Isotope Signatures (δ13C, δ15N) of Fagus sylvatica L. on Soils with Contrasting Water Supply. Ecosystems 2013. [DOI: 10.1007/s10021-013-9692-x] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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17
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Long-term forest soil acidification, nutrient leaching and vegetation development: Linking modelling and surveys of a primeval spruce forest in the Ukrainian Transcarpathian Mts. Ecol Modell 2012. [DOI: 10.1016/j.ecolmodel.2012.06.025] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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18
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Templer PH, Mack MC, Chapin FS, Christenson LM, Compton JE, Crook HD, Currie WS, Curtis CJ, Dail DB, D'Antonio CM, Emmett BA, Epstein HE, Goodale CL, Gundersen P, Hobbie SE, Holland K, Hooper DU, Hungate BA, Lamontagne S, Nadelhoffer KJ, Osenberg CW, Perakis SS, Schleppi P, Schimel J, Schmidt IK, Sommerkorn M, Spoelstra J, Tietema A, Wessel WW, Zak DR. Sinks for nitrogen inputs in terrestrial ecosystems: a meta-analysis of 15N tracer field studies. Ecology 2012; 93:1816-29. [PMID: 22928411 DOI: 10.1890/11-1146.1] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Effects of anthropogenic nitrogen (N) deposition and the ability of terrestrial ecosystems to store carbon (C) depend in part on the amount of N retained in the system and its partitioning among plant and soil pools. We conducted a meta-analysis of studies at 48 sites across four continents that used enriched 15N isotope tracers in order to synthesize information about total ecosystem N retention (i.e., total ecosystem 15N recovery in plant and soil pools) across natural systems and N partitioning among ecosystem pools. The greatest recoveries of ecosystem 15N tracer occurred in shrublands (mean, 89.5%) and wetlands (84.8%) followed by forests (74.9%) and grasslands (51.8%). In the short term (< 1 week after 15N tracer application), total ecosystem 15N recovery was negatively correlated with fine-root and soil 15N natural abundance, and organic soil C and N concentration but was positively correlated with mean annual temperature and mineral soil C:N. In the longer term (3-18 months after 15N tracer application), total ecosystem 15N retention was negatively correlated with foliar natural-abundance 15N but was positively correlated with mineral soil C and N concentration and C:N, showing that plant and soil natural-abundance 15N and soil C:N are good indicators of total ecosystem N retention. Foliar N concentration was not significantly related to ecosystem 15N tracer recovery, suggesting that plant N status is not a good predictor of total ecosystem N retention. Because the largest ecosystem sinks for 15N tracer were below ground in forests, shrublands, and grasslands, we conclude that growth enhancement and potential for increased C storage in aboveground biomass from atmospheric N deposition is likely to be modest in these ecosystems. Total ecosystem 15N recovery decreased with N fertilization, with an apparent threshold fertilization rate of 46 kg N x ha(-1) x yr(-1) above which most ecosystems showed net losses of applied 15N tracer in response to N fertilizer addition.
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Affiliation(s)
- P H Templer
- Department of Biology, Boston University, 5 Cummington Street, Boston, Massachusetts 02215, USA.
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19
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Jackson-Blake L, Helliwell RC, Britton AJ, Gibbs S, Coull MC, Dawson L. Controls on soil solution nitrogen along an altitudinal gradient in the Scottish uplands. THE SCIENCE OF THE TOTAL ENVIRONMENT 2012; 431:100-108. [PMID: 22673176 DOI: 10.1016/j.scitotenv.2012.05.019] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2012] [Revised: 05/04/2012] [Accepted: 05/07/2012] [Indexed: 06/01/2023]
Abstract
Nitrogen (N) deposition continues to threaten upland ecosystems, contributing to acidification, eutrophication and biodiversity loss. We present results from a monitoring study aimed at investigating the fate of this deposited N within a pristine catchment in the Cairngorm Mountains (Scotland). Six sites were established along an elevation gradient (486-908 m) spanning the key habitats of temperate maritime uplands. Bulk deposition chemistry, soil carbon content, soil solution chemistry, soil temperature and soil moisture content were monitored over a 5 year period. Results were used to assess spatial variability in soil solution N and to investigate the factors and processes driving this variability. Highest soil solution inorganic N concentrations were found in the alpine soils at the top of the hillslope. Soil carbon stock, soil solution dissolved organic carbon (DOC) and factors representing site hydrology were the best predictors of NO(3)(-) concentration, with highest concentrations at low productivity sites with low DOC and freely-draining soils. These factors act as proxies for changing net biological uptake and soil/water contact time, and therefore support the hypothesis that spatial variations in soil solution NO(3)(-) are controlled by habitat N retention capacity. Soil percent carbon was a better predictor of soil solution inorganic N concentration than mass of soil carbon. NH(4)(+) was less affected by soil hydrology than NO(3)(-) and showed the effects of net mineralization inputs, particularly at Racomitrium heath and peaty sites. Soil solution dissolved organic N concentration was strongly related to both DOC and temperature, with a stronger temperature effect at more productive sites. Due to the spatial heterogeneity in N leaching potential, a fine-scale approach to assessing surface water vulnerability to N leaching is recommended over the broad scale, critical loads approach currently in use, particularly for sensitive areas.
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Affiliation(s)
- L Jackson-Blake
- James Hutton Institute, Craigiebuckler, Aberdeen, AB15 8QH, United Kingdom.
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20
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Oulehle F, Cosby BJ, Wright RF, Hruška J, Kopáček J, Krám P, Evans CD, Moldan F. Modelling soil nitrogen: the MAGIC model with nitrogen retention linked to carbon turnover using decomposer dynamics. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2012; 165:158-166. [PMID: 22459669 DOI: 10.1016/j.envpol.2012.02.021] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2011] [Revised: 02/09/2012] [Accepted: 02/21/2012] [Indexed: 05/31/2023]
Abstract
We present a new formulation of the acidification model MAGIC that uses decomposer dynamics to link nitrogen (N) cycling to carbon (C) turnover in soils. The new model is evaluated by application to 15-30 years of water chemistry data at three coniferous-forested sites in the Czech Republic where deposition of sulphur (S) and N have decreased by >80% and 40%, respectively. Sulphate concentrations in waters have declined commensurately with S deposition, but nitrate concentrations have shown much larger decreases relative to N deposition. This behaviour is inconsistent with most conceptual models of N saturation, and with earlier versions of MAGIC which assume N retention to be a first-order function of N deposition and/or controlled by the soil C/N ratio. In comparison with earlier versions, the new formulation more correctly simulates observed short-term changes in nitrate leaching, as well as long-term retention of N in soils. The model suggests that, despite recent deposition reductions and recovery, progressive N saturation will lead to increased future nitrate leaching, ecosystem eutrophication and re-acidification.
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Affiliation(s)
- F Oulehle
- Centre for Ecology and Hydrology, Deiniol Road, Bangor LL57 2UW, UK.
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21
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Temperton VM, Märtin LLA, Röder D, Lücke A, Kiehl K. Effects of four different restoration treatments on the natural abundance of (15)n stable isotopes in plants. FRONTIERS IN PLANT SCIENCE 2012; 3:70. [PMID: 22645597 PMCID: PMC3355755 DOI: 10.3389/fpls.2012.00070] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/03/2011] [Accepted: 03/26/2012] [Indexed: 06/01/2023]
Abstract
δ(15)N signals in plant and soil material integrate over a number of biogeochemical processes related to nitrogen (N) and therefore provide information on net effects of multiple processes on N dynamics. In general little is known in many grassland restoration projects on soil-plant N dynamics in relation to the restoration treatments. In particular, δ(15)N signals may be a useful tool to assess whether abiotic restoration treatments have produced the desired result. In this study we used the range of abiotic and biotic conditions provided by a restoration experiment to assess to whether the restoration treatments and/or plant functional identity and legume neighborhood affected plant δ(15)N signals. The restoration treatments consisted of hay transfer and topsoil removal, thus representing increasing restoration effort, from no restoration measures, through biotic manipulation to major abiotic manipulation. We measured δ(15)N and %N in six different plant species (two non-legumes and four legumes) across the restoration treatments. We found that restoration treatments were clearly reflected in δ(15)N of the non-legume species, with very depleted δ(15)N associated with low soil N, and our results suggest this may be linked to uptake of ammonium (rather than nitrate). The two non-legume species differed considerably in their δ(15)N signals, which may be related to the two species forming different kinds of mycorrhizal symbioses. Plant δ(15)N signals could clearly separate legumes from non-legumes, but our results did not allow for an assessment of legume neighborhood effects on non-legume δ(15)N signals. We discuss our results in the light of what the δ(15)N signals may be telling us about plant-soil N dynamics and their potential value as an indicator for N dynamics in restoration.
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Affiliation(s)
| | - Lea L. A. Märtin
- IBG-2: Plant Sciences, Forschungszentrum Jülich GmbHJülich, Germany
- Department of Biogeography, University of BayreuthBayreuth, Germany
| | - Daniela Röder
- Vegetation Ecology, Technische Universität MünchenFreising-Weihenstephan, Germany
| | - Andreas Lücke
- IBG-3: Agrosphere, Forschungszentrum Jülich GmbHJülich, Germany
| | - Kathrin Kiehl
- Vegetation Ecology and Botany, University of Applied Sciences OsnabrueckOsnabrück, Germany
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22
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Daniels SM, Evans MG, Agnew CT, Allott TEH. Ammonium release from a blanket peatland into headwater stream systems. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2012; 163:261-272. [PMID: 22285801 DOI: 10.1016/j.envpol.2012.01.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2011] [Revised: 10/04/2011] [Accepted: 01/10/2012] [Indexed: 05/31/2023]
Abstract
Hydrochemical sampling of South Pennine (UK) headwater streams draining eroded upland peatlands demonstrates these systems are nitrogen saturated, with significant leaching of dissolved inorganic nitrogen (DIN), particularly ammonium, during both stormflow and baseflow conditions. DIN leaching at sub-catchment scale is controlled by geomorphological context; in catchments with low gully densities ammonium leaching dominates whereas highly gullied catchments leach ammonium and nitrate since lower water tables and increased aeration encourages nitrification. Stormflow flux calculations indicate that: approximately equivalent amounts of nitrate are deposited and exported; ammonium export significantly exceeds atmospheric inputs. This suggests two ammonium sources: high atmospheric loadings; and mineralisation of organic nitrogen stored in peat. Downstream trends indicate rapid transformation of leached ammonium into nitrate. It is important that low-order headwater streams are adequately considered when assessing impacts of atmospheric loads on the hydrochemistry of stream networks, especially with respect to erosion, climate change and reduced precipitation.
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Affiliation(s)
- S M Daniels
- Upland Environments Research Unit, Geography, School of Environment and Development, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK.
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23
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Rogora M, Arisci S, Marchetto A. The role of nitrogen deposition in the recent nitrate decline in lakes and rivers in Northern Italy. THE SCIENCE OF THE TOTAL ENVIRONMENT 2012; 417-418:214-223. [PMID: 22281043 DOI: 10.1016/j.scitotenv.2011.12.067] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2011] [Revised: 12/27/2011] [Accepted: 12/28/2011] [Indexed: 05/31/2023]
Abstract
Deposition of inorganic nitrogen (N) in north-western Italy is around 20-25 kg N ha(-1)y(-1), and has remained constant during the last 30 years. This flux of N caused saturation of terrestrial catchments and increasing levels of nitrate (NO(3)) in surface waters. Recently, monitoring data for both rivers and lakes have shown a reversal in NO(3) trends. This change was widespread, affecting high-altitude lakes in the Alps and subalpine lakes and rivers, and occurred at almost the same time at all sites. The seasonal pattern of NO(3) concentrations in running waters has shown a change in the last few years, with a tendency towards slightly lower leaching of NO(3) during the growing season. Atmospheric input of N has also shown a recent decrease, mainly due to decreasing emissions and partly to the lower amount of precipitation occurring between 2003 and 2009. Surface waters are probably responding to these changing N inputs, but a further decrease of N deposition, especially reduced N, will be required to achieve full recovery from N saturation.
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Affiliation(s)
- Michela Rogora
- CNR Institute of Ecosystem Study, L.go Tonolli 50, I-28922 Verbania Pallanza, Italy.
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