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van Paassen JG, Britton AJ, Mitchell RJ, Street LE, Johnson D, Coupar A, Woodin SJ. Legacy effects of nitrogen and phosphorus additions on vegetation and carbon stocks of upland heaths. THE NEW PHYTOLOGIST 2020; 228:226-237. [PMID: 32432343 DOI: 10.1111/nph.16671] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Accepted: 05/12/2020] [Indexed: 06/11/2023]
Abstract
Soil carbon (C) pools and plant community composition are regulated by nitrogen (N) and phosphorus (P) availability. Atmospheric N deposition impacts ecosystem C storage, but the direction of response varies between systems. Phosphorus limitation may constrain C storage response to N, hence P application to increase plant productivity and thus C sequestration has been suggested. We revisited a 23-yr-old field experiment where N and P had been applied to upland heath, a widespread habitat supporting large soil C stocks. At 10 yr after the last nutrient application we quantified long-term changes in vegetation composition and in soil and vegetation C and P stocks. Nitrogen addition, particularly when combined with P, strongly influenced vegetation composition, favouring grasses over Calluna vulgaris, and led to a reduction in vegetation C stocks. However, soil C stocks did not respond to nutrient treatments. We found 40% of the added P had accumulated in the soil. This study showed persistent effects of N and N + P on vegetation composition, whereas effects of P alone were small and showed recovery. We found no indication that P application could mitigate the effects of N on vegetation or increase C sequestration in this system.
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Affiliation(s)
- José G van Paassen
- School of Biological Sciences, University of Aberdeen, Aberdeen, AB24 3UU, UK
- The James Hutton Institute, Craigiebuckler, Aberdeen, AB15 8QH, UK
| | - Andrea J Britton
- The James Hutton Institute, Craigiebuckler, Aberdeen, AB15 8QH, UK
| | - Ruth J Mitchell
- The James Hutton Institute, Craigiebuckler, Aberdeen, AB15 8QH, UK
| | - Lorna E Street
- School of Geosciences, University of Edinburgh, Edinburgh, EH9 3FF, UK
| | - David Johnson
- Department of Earth and Environmental Sciences, University of Manchester, Manchester, M13 9PT, UK
| | - Andrew Coupar
- Scottish Natural Heritage, The Links, Golspie, KW10 6UB, UK
| | - Sarah J Woodin
- School of Biological Sciences, University of Aberdeen, Aberdeen, AB24 3UU, UK
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Gutiérrez-Larruga B, Estébanez-Pérez B, Ochoa-Hueso R. Effects of Nitrogen Deposition on the Abundance and Metabolism of Lichens: A Meta-analysis. Ecosystems 2019. [DOI: 10.1007/s10021-019-00431-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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3
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Wang CH, Munzi S, Wang M, Jia YZ, Tao W. Increasing nitrogen depositions can reduce lichen viability and limit winter food for an endangered Chinese monkey. Basic Appl Ecol 2019. [DOI: 10.1016/j.baae.2018.10.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Taboada A, Calvo-Fernández J, Marcos E, Calvo L. Plant and vegetation functional responses to cumulative high nitrogen deposition in rear-edge heathlands. THE SCIENCE OF THE TOTAL ENVIRONMENT 2018; 637-638:980-990. [PMID: 29763879 DOI: 10.1016/j.scitotenv.2018.05.092] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Revised: 05/07/2018] [Accepted: 05/07/2018] [Indexed: 06/08/2023]
Abstract
Elevated atmospheric nitrogen (N) deposition is a major driver of change, altering the structure/functioning of nutrient-poor Calluna vulgaris-heathlands over Europe. These effects amply proven for north-western/central heathlands may, however, vary across the ecosystem's distribution, especially at the range limits, as heathlands are highly vulnerable to land-use changes combined with present climate change. This is an often overlooked and greatly understudied aspect of the ecology of heathlands facing global change. We investigated the effects of five N-fertilisation treatments simulating a range of N deposition rates (0, 10, 20, and 50 kg N ha-1 yr-1 for 1 year; and 56 kg N ha-1 yr-1 for 9 years) on the Calluna-plants, the plant functional groups, species composition and richness of two life-cycle stages (building/young- and mature-phase) of Calluna-heathlands at their rear-edge limit. Our findings revealed a dose-related response of the shoot length and number of flowers of young and mature Calluna-plants to the addition of N, adhering to the findings from other heathland locations. However, cumulative high-N loading reduced the annual growth and flowering of young plants, showing early signs of N saturation. The different plant functional groups showed contrasting responses to the cumulative addition of N: annual/perennial forbs and annual graminoids increased with quite low values; perennial graminoids were rather abundant in young heathlands but only slightly augmented in mature ones; while bryophytes and lichens strongly declined at the two heathland life-cycle stages. Meanwhile there were no significant N-driven changes in plant species composition and richness. Our results demonstrated that Calluna-heathlands at their low-latitude distribution limit are moderately resistant to cumulative high-N loading. As north-western/central European heathlands under high-N inputs broadly experienced the loss of plant diversity and pronounced changes in plant species dominance, rear-edge locations may be of critical importance to unravel the mechanisms of heathland resilience to future global change.
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Affiliation(s)
- Angela Taboada
- Area of Ecology, University of León, E-24071 León, Spain; Institute of Environmental Research (IMA), University of Léon, E-24071 León, Spain.
| | - Javier Calvo-Fernández
- Area of Ecology, University of León, E-24071 León, Spain; Institute of Environmental Research (IMA), University of Léon, E-24071 León, Spain
| | - Elena Marcos
- Area of Ecology, University of León, E-24071 León, Spain; Institute of Environmental Research (IMA), University of Léon, E-24071 León, Spain
| | - Leonor Calvo
- Area of Ecology, University of León, E-24071 León, Spain; Institute of Environmental Research (IMA), University of Léon, E-24071 León, Spain
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Chiwa M, Sheppard LJ, Leith ID, Leeson SR, Tang YS, Neil Cape J. Long-term interactive effects of N addition with P and K availability on N status of Sphagnum. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2018; 237:468-472. [PMID: 29510366 DOI: 10.1016/j.envpol.2018.02.076] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Revised: 02/08/2018] [Accepted: 02/24/2018] [Indexed: 06/08/2023]
Abstract
Little information exists concerning the long-term interactive effect of nitrogen (N) addition with phosphorus (P) and potassium (K) on Sphagnum N status. This study was conducted as part of a long-term N manipulation on Whim bog in south Scotland to evaluate the long-term alleviation effects of phosphorus (P) and potassium (K) on N saturation of Sphagnum (S. capillifolium). On this ombrotrophic peatland, where ambient deposition was 8 kg N ha-1 yr-1, 56 kg N ha-1 yr-1 of either ammonium (NH4+, Nred) or nitrate (NO3-, Nox) with and without P and K, were added over 11 years. Nutrient concentrations of Sphagnum stem and capitulum, and pore water quality of the Sphagnum layer were assessed. The N-saturated Sphagnum caused by long-term (11 years) and high doses (56 kg N ha-1 yr-1) of reduced N was not completely ameliorated by P and K addition; N concentrations in Sphagnum capitula for Nred 56 PK were comparable with those for Nred 56, although N concentrations in Sphagnum stems for Nred 56 PK were lower than those for Nred 56. While dissolved inorganic nitrogen (DIN) concentrations in pore water for Nred 56 PK were not different from Nred 56, they were lower for Nox 56 PK than for Nox 56 whose stage of N saturation had not advanced compared to Nred 56. These results indicate that increasing P and K availability has only a limited amelioration effect on the N assimilation of Sphagnum at an advanced stage of N saturation. This study concluded that over the long-term P and K additions will not offset the N saturation of Sphagnum.
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Affiliation(s)
- Masaaki Chiwa
- Kyushu University Forest, Kyushu University, 394 Tsubakuro, Sasaguri, Fukuoka, 811-2415, Japan.
| | - Lucy J Sheppard
- Centre for Ecology & Hydrology (CEH) Edinburgh, Bush Estate, Penicuik, EH26 0QB, UK
| | - Ian D Leith
- Centre for Ecology & Hydrology (CEH) Edinburgh, Bush Estate, Penicuik, EH26 0QB, UK
| | - Sarah R Leeson
- Centre for Ecology & Hydrology (CEH) Edinburgh, Bush Estate, Penicuik, EH26 0QB, UK
| | - Y Sim Tang
- Centre for Ecology & Hydrology (CEH) Edinburgh, Bush Estate, Penicuik, EH26 0QB, UK
| | - J Neil Cape
- Centre for Ecology & Hydrology (CEH) Edinburgh, Bush Estate, Penicuik, EH26 0QB, UK
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Stiles WAV, Rowe EC, Dennis P. Long-term nitrogen and phosphorus enrichment alters vegetation species composition and reduces carbon storage in upland soil. THE SCIENCE OF THE TOTAL ENVIRONMENT 2017; 593-594:688-694. [PMID: 28366869 DOI: 10.1016/j.scitotenv.2017.03.136] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2017] [Revised: 03/14/2017] [Accepted: 03/15/2017] [Indexed: 06/07/2023]
Abstract
Reactive nitrogen (N) deposition can affect ecosystem processes, particularly in oligotrophic upland habitats. Phosphorus (P) addition has been proposed to reduce the effects of N enrichment on N leaching and acidification, since P limitation can reduce biomass production and consequent sequestration of reactive N. However, biodiversity is often reduced in more productive ecosystems and P limitation may protect against this effect. Responses to P availability in instances of high N deposition are poorly understood. This study investigated the ecosystem response to alleviation of P limitation, using a long-term nutrient addition experiment (1996-2012) three years after ceasing N inputs and 15years after a single P application. Substantial differences were observed in the structure and composition of vegetation species and above-ground vegetation biomass. Vegetation height was greater in the N+P addition treatments (+38% cf. control), with increased cryptogam cover (+47%), whereas N addition increased graminoid species cover (+68%). Vegetation diversity was significantly reduced by the addition of P (-21%), indicating that P limitation is likely to be an important mechanism that limits biodiversity loss in upland habitats exposed to chronic N deposition. Significant differences in soil C and N contents were also observed between treatments. Relative to control, the addition of N increased soil C (+11%) and N (+11%) pool sizes, whereas the addition of N and P reduced soil C (-12%) and N (-13%) pool sizes. This demonstrated the importance of P availability for upland ecosystem processes, and highlights the long-term effects of P addition on vegetation species composition and C storage. Thus, the addition of P cannot be endorsed as a method for reducing impacts of N deposition. Capsule: Phosphorus limitation is a major mechanism governing ecosystem processes in situations of high atmospheric nitrogen deposition.
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Affiliation(s)
- William A V Stiles
- Institute of Biological, Environmental and Rural Sciences, Penglais Campus, Aberystwyth University, Wales SY23 3DD, United Kingdom.
| | - Edwin C Rowe
- Centre for Ecology & Hydrology, Bangor, Environment Centre Wales, Bangor LL57 2UP, United Kingdom
| | - Peter Dennis
- Institute of Biological, Environmental and Rural Sciences, Penglais Campus, Aberystwyth University, Wales SY23 3DD, United Kingdom
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Carter TS, Clark CM, Fenn ME, Jovan S, Perakis SS, Riddell J, Schaberg PG, Greaver TL, Hastings MG. Mechanisms of nitrogen deposition effects on temperate forest lichens and trees. Ecosphere 2017; 8:10.1002/ecs2.1717. [PMID: 34327038 PMCID: PMC8318115 DOI: 10.1002/ecs2.1717] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
We review the mechanisms of deleterious nitrogen (N) deposition impacts on temperate forests, with a particular focus on trees and lichens. Elevated anthropogenic N deposition to forests has varied effects on individual organisms depending on characteristics both of the N inputs (form, timing, amount) and of the organisms (ecology, physiology) involved. Improved mechanistic knowledge of these effects can aid in developing robust predictions of how organisms respond to either increases or decreases in N deposition. Rising N levels affect forests in micro- and macroscopic ways from physiological responses at the cellular, tissue, and organism levels to influencing individual species and entire communities and ecosystems. A synthesis of these processes forms the basis for the overarching themes of this paper, which focuses on N effects at different levels of biological organization in temperate forests. For lichens, the mechanisms of direct effects of N are relatively well known at cellular, organismal, and community levels, though interactions of N with other stressors merit further research. For trees, effects of N deposition are better understood for N as an acidifying agent than as a nutrient; in both cases, the impacts can reflect direct effects on short time scales and indirect effects mediated through long-term soil and belowground changes. There are many gaps on fundamental N use and cycling in ecosystems, and we highlight the most critical gaps for understanding potential deleterious effects of N deposition. For lichens, these gaps include both how N affects specific metabolic pathways and how N is metabolized. For trees, these gaps include understanding the direct effects of N deposition onto forest canopies, the sensitivity of different tree species and mycorrhizal symbionts to N, the influence of soil properties, and the reversibility of N and acidification effects on plants and soils. Continued study of how these N response mechanisms interact with one another, and with other dimensions of global change, remains essential for predicting ongoing changes in lichen and tree populations across North American temperate forests.
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Affiliation(s)
- Therese S. Carter
- US Global Change Research Program, ICF Contractor, 1800 G Street NW, Suite 9100, Washington, D.C. 20006 USA
- Department of Chemistry, Brown University, 324 Brook Street, Providence, Rhode Island 02912 USA
| | - Christopher M. Clark
- US EPA, Office of Research and Development, Global Change Research Group, 1200 Pennsylvania Avenue, N. W., Washington, D.C. 20460 USA
| | - Mark E. Fenn
- USDA Forest Service, Pacific Southwest Research Station, 4955 Canyon Crest Drive, Riverside, California 92507 USA
| | - Sarah Jovan
- USDA Forest Service, Pacific Northwest Research Station, 620 SW Main Street, Portland, Oregon 97205 USA
| | - Steven S. Perakis
- US Geological Survey, Forest and Rangeland Ecosystem Science Center, Corvallis, Oregon 97331 USA
| | - Jennifer Riddell
- Sustainable Technology Program, Mendocino College, 1000 Hensley Creek Road, Ukiah, California 95482 USA
| | - Paul G. Schaberg
- USDA Forest Service, Northern Research Station, 705 Spear Street S, Burlington, Vermont 05405 USA
| | - Tara L. Greaver
- National Center for Environmental Assessment, US Environmental Protection Agency, Research Triangle Park, North Carolina 27711 USA
| | - Meredith G. Hastings
- Department of Earth, Environmental, and Planetary Sciences, Institute at Brown for Environment and Society, Brown University, 324 Brook Street, Providence, Rhode Island 02912 USA
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Street LE, Burns NR, Woodin SJ. Slow recovery of High Arctic heath communities from nitrogen enrichment. THE NEW PHYTOLOGIST 2015; 206:682-695. [PMID: 25599914 DOI: 10.1111/nph.13265] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Accepted: 11/28/2014] [Indexed: 06/04/2023]
Abstract
Arctic ecosystems are strongly nutrient limited and exhibit dramatic responses to nitrogen (N) enrichment, the reversibility of which is unknown. This study uniquely assesses the potential for tundra heath to recover from N deposition and the influence of phosphorus (P) availability on recovery. We revisited an experiment in Svalbard, established in 1991, in which N was applied at rates representing atmospheric N deposition in Europe (10 and 50 kg N ha(-1) yr(-1) ; 'low' and 'high', respectively) for 3-8 yr. We investigated whether significant effects on vegetation composition and ecosystem nutrient status persisted up to 18 yr post-treatment. Although the tundra heath is no longer N saturated, N treatment effects persist and are strongly P-dependent. Vegetation was more resilient to N where no P was added, although shrub cover is still reduced in low-N plots. Where P was also added (5 kg P ha(-1) yr(-1) ), there are still effects of low N on community composition and nutrient dynamics. High N, with and without P, has many lasting impacts. Importantly, N + P has caused dramatically increased moss abundance, which influences nutrient dynamics. Our key finding is that Arctic ecosystems are slow to recover from even small N inputs, particularly where P is not limiting.
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Affiliation(s)
- Lorna E Street
- IBES, University of Aberdeen, St Machar Drive, Aberdeen, AB24 3UU, UK
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Ochoa-Hueso R, Stevens CJ, Ortiz-Llorente MJ, Manrique E. Soil chemistry and fertility alterations in response to N application in a semiarid Mediterranean shrubland. THE SCIENCE OF THE TOTAL ENVIRONMENT 2013; 452-453:78-86. [PMID: 23500401 DOI: 10.1016/j.scitotenv.2013.02.049] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2012] [Revised: 02/15/2013] [Accepted: 02/16/2013] [Indexed: 06/01/2023]
Abstract
N deposition is currently affecting nutrient cycling in terrestrial ecosystems. We studied the effects of four years of N application (0, 10, 20 and 50 kg N ha(-1) year(-1)+background deposition) on soil chemistry and fertility in a semiarid shrubland in central Spain. Soil pH and nutrient availability fluctuated seasonally. The inorganic-N fraction in soil was dominated by nitrate, as expected in calcareous soils. N application increased inorganic N availability in soil. There was a negative correlation between N application and soil K(+) availability and pH, measured as the % change after four years. Soil N and C storage (evaluated as the % change) slightly increased after four years. Our data suggest that, in the short-term, the seasonality of nutrients overwhelm any chemical alteration related to N deposition. However, the potential implication of continuous N addition on soil chemistry in the long-term is not well understood.
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Affiliation(s)
- Raúl Ochoa-Hueso
- Museo Nacional de Ciencias Naturales, Consejo Superior de Investigaciones Científicas (MNCN-CSIC), Madrid, Spain.
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Southon GE, Field C, Caporn SJM, Britton AJ, Power SA. Nitrogen deposition reduces plant diversity and alters ecosystem functioning: field-scale evidence from a nationwide survey of UK heathlands. PLoS One 2013; 8:e59031. [PMID: 23637736 PMCID: PMC3639280 DOI: 10.1371/journal.pone.0059031] [Citation(s) in RCA: 80] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2012] [Accepted: 02/11/2013] [Indexed: 11/18/2022] Open
Abstract
Findings from nitrogen (N) manipulation studies have provided strong evidence of the detrimental impacts of elevated N deposition on the structure and functioning of heathland ecosystems. Few studies, however, have sought to establish whether experimentally observed responses are also apparent under natural, field conditions. This paper presents the findings of a nationwide field-scale evaluation of British heathlands, across broad geographical, climatic and pollution gradients. Fifty two heathlands were selected across an N deposition gradient of 5.9 to 32.4 kg ha(-1) yr(-1). The diversity and abundance of higher and lower plants and a suite of biogeochemical measures were evaluated in relation to climate and N deposition indices. Plant species richness declined with increasing temperature and N deposition, and the abundance of nitrophilous species increased with increasing N. Relationships were broadly similar between upland and lowland sites, with the biggest reductions in species number associated with increasing N inputs at the low end of the deposition range. Both oxidised and reduced forms of N were associated with species declines, although reduced N appears to be a stronger driver of species loss at the functional group level. Plant and soil biochemical indices were related to temperature, rainfall and N deposition. Litter C:N ratios and enzyme (phenol-oxidase and phosphomonoesterase) activities had the strongest relationships with site N inputs and appear to represent reliable field indicators of N deposition. This study provides strong, field-scale evidence of links between N deposition--in both oxidised and reduced forms--and widespread changes in the composition, diversity and functioning of British heathlands. The similarity of relationships between upland and lowland environments, across broad spatial and climatic gradients, highlights the ubiquity of relationships with N, and suggests that N deposition is contributing to biodiversity loss and changes in ecosystem functioning across European heathlands.
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Affiliation(s)
- Georgina E. Southon
- Division of Biology, Imperial College London, Ascot, Berkshire, United Kingdom
| | - Christopher Field
- Division of Biology and Conservation Ecology, Manchester Metropolitan University, Manchester, United Kingdom
| | - Simon J. M. Caporn
- Division of Biology and Conservation Ecology, Manchester Metropolitan University, Manchester, United Kingdom
| | | | - Sally A. Power
- Division of Biology, Imperial College London, Ascot, Berkshire, United Kingdom
- Hawkesbury Institute for the Environment, University of Western Sydney, Penrith New South Wales, Australia
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Edmondson J, Terribile E, Carroll JA, Price EAC, Caporn SJM. The legacy of nitrogen pollution in heather moorlands: ecosystem response to simulated decline in nitrogen deposition over seven years. THE SCIENCE OF THE TOTAL ENVIRONMENT 2013; 444:138-144. [PMID: 23262328 DOI: 10.1016/j.scitotenv.2012.11.074] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2012] [Revised: 11/15/2012] [Accepted: 11/21/2012] [Indexed: 06/01/2023]
Abstract
Eutrophication and acidification of heather moorlands by chronic atmospheric nitrogen (N) pollution, is of major concern within these internationally important ecosystems. However, in the UK and Western Europe generally emissions of NO(y) and NH(x) peaked during the 20th century. Due to the history and scale of atmospheric N pollution, the legacy of these high levels of N deposition, through accumulation in soil, may hinder or prevent ecosystem recovery. Effects of N pollution on heather moorland were investigated throughout the ecosystem including; the dominant plant species, Calluna vulgaris, the bryophyte and lichen community and the soil system using a long-term experiment simulating wet N deposition. We observed an increase in C. vulgaris height, shoot extension and canopy density, litter mineral N, total N concentration, N:P and C:N ratios in response to N addition. Bryophyte species diversity, bryophyte and lichen frequency and the frequency of two individual bryophyte species (Lophozia ventricosa and Campylopus flexuosus) were significantly reduced by N addition. We developed an N recovery experiment, using a split-plot design, on the long-term N treatment plots to investigate ecosystem response to a simulated decline in N deposition. Two years after cessation of N treatment the only ecosystem component that responded to the recovery experiment was C. vulgaris shoot extension, however after seven years of recovery there were significant declines in litter total N concentration and mineral N and an increase in litter C:N ratio. Although bryophytes and lichens form a close relationship with atmospheric N deposition these organisms did not show a significant response to the N recovery experiment, two years after cessation of N treatment. These data indicate that low nutrient ecosystems, such as moorlands, have the capacity to respond to declines in N deposition however the accumulation of pollution may hinder recovery of sensitive organisms, such as bryophytes and lichens.
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Affiliation(s)
- J Edmondson
- School of Science and the Environment, Manchester Metropolitan University, Manchester, Oxford Road, M1 5GD, UK.
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Southon GE, Green ER, Jones AG, Barker CG, Power SA. Long-term nitrogen additions increase likelihood of climate stress and affect recovery from wildfire in a lowland heath. GLOBAL CHANGE BIOLOGY 2012; 18:2824-37. [PMID: 24501060 DOI: 10.1111/j.1365-2486.2012.02732.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2011] [Accepted: 02/14/2012] [Indexed: 05/23/2023]
Abstract
Increases in the emissions and associated atmospheric deposition of nitrogen (N) have the potential to cause significant changes to the structure and function of N-limited ecosystems. Here, we present the results of a long-term (13 year) experiment assessing the impacts of N addition (30 kg ha(-1) yr(-1) ) on a UK lowland heathland under a wide range of environmental conditions, including the occurrence of prolonged natural drought episodes and a severe summer fire. Our findings indicate that elevated N deposition results in large, persistent effects on Calluna growth, phenology and chemistry, severe suppression of understorey lichen flora and changes in soil biogeochemistry. Growing season rainfall was found to be a strong driver of inter-annual variation in Calluna growth and, although interactions between N and rainfall for shoot growth were not significant until the later phase of the experiment, N addition exacerbated the extent of drought injury to Calluna shoots following naturally occurring droughts in 2003 and 2009. Following a severe wildfire at the experimental site in 2006, heathland regeneration dynamics were significantly affected by N, with a greater abundance of pioneering moss species and suppression of the lichen flora in plots receiving N additions. Significant interactions between climate and N were also apparent post fire, with the characteristic stimulation in Calluna growth in +N plots suppressed during dry years. Carbon (C) and N budgets demonstrate large increases in both above- and below-ground stocks of these elements in N-treated plots prior to the fire, despite higher levels of soil microbial activity and organic matter turnover. Although much of the organic material was removed during the fire, pre-existing treatment differences were still evident following the burn. Post fire accumulation of below-ground C and N stocks was increased rapidly in N-treated plots, highlighting the role of N deposition in ecosystem C sequestration.
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Affiliation(s)
- Georgina E Southon
- Division of Biology, Imperial College London, Silwood Park, Ascot, Berkshire, SL5 7PY, UK
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Fritz C, van Dijk G, Smolders AJP, Pancotto VA, Elzenga TJTM, Roelofs JGM, Grootjans AP. Nutrient additions in pristine Patagonian Sphagnum bog vegetation: can phosphorus addition alleviate (the effects of) increased nitrogen loads. PLANT BIOLOGY (STUTTGART, GERMANY) 2012; 14:491-499. [PMID: 22221295 DOI: 10.1111/j.1438-8677.2011.00527.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Sphagnum-bog ecosystems have a limited capability to retain carbon and nutrients when subjected to increased nitrogen (N) deposition. Although it has been proposed that phosphorus (P) can dilute negative effects of nitrogen by increasing biomass production of Sphagnum mosses, it is still unclear whether P-addition can alleviate physiological N-stress in Sphagnum plants. A 3-year fertilisation experiment was conducted in lawns of a pristine Sphagnum magellanicum bog in Patagonia, where competing vascular plants were practically absent. Background wet deposition of nitrogen was low (≈ 0.1-0.2 g · N · m(-2) · year(-1)). Nitrogen (4 g · N · m(-2) · year(-1)) and phosphorus (1 g · P · m(-2) · year(-1)) were applied, separately and in combination, six times during the growing season. P-addition substantially increased biomass production of Sphagnum. Nitrogen and phosphorus changed the morphology of Sphagnum mosses by enhancing height increment, but lowering moss stem density. In contrast to expectations, phosphorus failed to alleviate physiological stress imposed by excess nitrogen (e.g. amino acid accumulation, N-saturation and decline in photosynthetic rates). We conclude that despite improving growth conditions by P-addition, Sphagnum-bog ecosystems remain highly susceptible to nitrogen additions. Increased susceptibility to desiccation by nutrients may even worsen the negative effects of excess nitrogen especially in windy climates like in Patagonia.
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Affiliation(s)
- C Fritz
- Aquatic Ecology, Institute for Water and Wetland Research, Radboud University, Nijmegen, The Netherlands.
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Ochoa-Hueso R, Allen EB, Branquinho C, Cruz C, Dias T, Fenn ME, Manrique E, Pérez-Corona ME, Sheppard LJ, Stock WD. Nitrogen deposition effects on Mediterranean-type ecosystems: an ecological assessment. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2011; 159:2265-79. [PMID: 21277663 DOI: 10.1016/j.envpol.2010.12.019] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2010] [Revised: 12/14/2010] [Accepted: 12/21/2010] [Indexed: 05/22/2023]
Abstract
We review the ecological consequences of N deposition on the five Mediterranean regions of the world. Seasonality of precipitation and fires regulate the N cycle in these water-limited ecosystems, where dry N deposition dominates. Nitrogen accumulation in soils and on plant surfaces results in peaks of availability with the first winter rains. Decoupling between N flushes and plant demand promotes losses via leaching and gas emissions. Differences in P availability may control the response to N inputs and susceptibility to exotic plant invasion. Invasive grasses accumulate as fuel during the dry season, altering fire regimes. California and the Mediterranean Basin are the most threatened by N deposition; however, there is limited evidence for N deposition impacts outside of California. Consequently, more research is needed to determine critical loads for each region and vegetation type based on the most sensitive elements, such as changes in lichen species composition and N cycling.
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Affiliation(s)
- Raúl Ochoa-Hueso
- Department of Plant Physiology and Ecology, Centro de Ciencias Medioambientales, Consejo Superior de Investigaciones Científicas, 28006 Madrid, Spain.
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15
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Johansson O, Olofsson J, Giesler R, Palmqvist K. Lichen responses to nitrogen and phosphorus additions can be explained by the different symbiont responses. THE NEW PHYTOLOGIST 2011; 191:795-805. [PMID: 21534972 DOI: 10.1111/j.1469-8137.2011.03739.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
• Responses to simulated nitrogen (N) deposition with or without added phosphorus (P) were investigated for three contrasting lichen species - the N-sensitive Alectoria sarmentosa, the more N-tolerant Platismatia glauca and the N(2) -fixing Lobaria pulmonaria- in a field experiment. • To examine whether nutrient limitation differed between the photobiont and the mycobiont within the lichen, the biomass responses of the respective bionts were estimated. • The lichenized algal cells were generally N-limited, because N-stimulated algal growth in all three species. The mycobiont was P-limited in one species (A. sarmentosa), but the growth response of the mycobionts was complex, as fungal growth is also dependent on a reliable carbon export from the photobiont, which may have been the reason for the decrease of the mycobiont with N addition in P. glauca. • Our findings showed that P availability was an important factor when studying effects of N deposition, as P supply can both mitigate and intensify the negative effects of N on epiphytic lichens.
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Affiliation(s)
- Otilia Johansson
- Department of Ecology and Environmental Science, Umeå University, SE-901 87 Umeå, Sweden
| | - Johan Olofsson
- Department of Ecology and Environmental Science, Umeå University, SE-901 87 Umeå, Sweden
| | - Reiner Giesler
- Climate Impacts Research Centre, Department of Ecology and Environmental Science, Umeå University, SE-981 07 Abisko, Sweden
| | - Kristin Palmqvist
- Department of Ecology and Environmental Science, Umeå University, SE-901 87 Umeå, Sweden
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Edmondson JL, Carroll JA, Price EAC, Caporn SJM. Bio-indicators of nitrogen pollution in heather moorland. THE SCIENCE OF THE TOTAL ENVIRONMENT 2010; 408:6202-6209. [PMID: 20888029 DOI: 10.1016/j.scitotenv.2010.08.060] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2010] [Revised: 08/26/2010] [Accepted: 08/30/2010] [Indexed: 05/29/2023]
Abstract
Heather moorlands are internationally important ecosystems that are highly sensitive to eutrophication and acidification by reactive atmospheric nitrogen (N) deposition. We used a long-term experiment simulating wet-deposition of N on heather moorland to identify potential bio-indicators of N deposition. These indicators were subsequently employed in a survey covering a N deposition gradient ranging from approximately 7 to 31kg N ha(-1) yr(-1), at selected sites throughout the UK. In this regional survey litter phenol oxidase activity and bryophyte species richness were negatively associated with N deposition. Calluna vulgaris N:P ratios and litter extractable N were positively correlated with N deposition. The use of the suite of four bio-indicators has the potential to provide rapid assessment of the extent of N saturation of heather moorland sites and moorland ecosystem functioning, and has significant advantages over reliance on single measures such as soil N status or an individual bio-indicator species.
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Affiliation(s)
- J L Edmondson
- Department of Environmental and Geographical Sciences, Manchester Metropolitan University, Chester Street, Manchester, M1 5GD, UK.
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Hejcman M, Száková J, Schellberg J, Srek P, Tlustos P, Balík J. The Rengen Grassland experiment: bryophytes biomass and element concentrations after 65 years of fertilizer application. ENVIRONMENTAL MONITORING AND ASSESSMENT 2010; 166:653-662. [PMID: 19543996 DOI: 10.1007/s10661-009-1030-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2008] [Accepted: 06/03/2009] [Indexed: 05/27/2023]
Abstract
The Rengen Grassland Experiment in Germany, established in 1941, consists of the following fertilizer treatments applied under a two cut management: control, Ca, CaN, CaNP, CaNP-KCl, and CaNP-K(2)SO(4). The aim of this study was (1) to identify effects of fertilizer application on biomass and species composition of bryophytes and (2) to investigate the impact of fertilizer application on macro- (N, P, K, Ca, Mg), micro- (Cu, Fe, Mn, Zn), and toxic (As, Cd, Cr, Pb, Ni) element concentrations in bryophyte biomass. In June 2006, Rhytidiadelphus squarrosus was the only bryophyte species recorded in the control. In treatment Ca, R. squarrosus was the dominant bryophyte species whereas Brachythecium rutabulum occurred sporadically only in a single plot of that treatment. The latter was the only bryophyte species collected in CaN, CaNP, CaNP-KCl, and CaNP-K(2)SO(4) treatments. Dry matter accumulation of bryophytes was highest in the control (180 g m(-2)) followed by Ca (46 g m(-2)), CaNP (25 g m(-2)), CaNP-KCl (15 g m(-2)), CaNP-K(2)SO(4) (9 g m(-2)), and CaN (2 g m(-2)) treatments. A negative correlation between biomass production of bryophytes and dry matter production of vascular plants was revealed up to a threshold value of 400 g m(-2). Above this limit, biomass production of bryophytes remained obviously unaffected by further increase in biomass production of vascular plants. A significant effect of treatment on As, Cd, Cr, Fe, Mn, Ni, Pb, P, Ca, Mg, K, and N concentrations was revealed. Concentrations of these elements were a function of amount of elements supplied with fertilizers. Bryophytes seem to be promising bio-indicators not only for airborne deposition of toxic element but also for fertilizer introduced as well.
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Affiliation(s)
- Michal Hejcman
- Department of Ecology, Czech University of Life Sciences, Kamýcká 1176, 165 21, Prague 6-Suchdol, Czech Republic.
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Arróniz-Crespo M, Leake JR, Horton P, Phoenix GK. Bryophyte physiological responses to, and recovery from, long-term nitrogen deposition and phosphorus fertilisation in acidic grassland. THE NEW PHYTOLOGIST 2008; 180:864-74. [PMID: 18801005 DOI: 10.1111/j.1469-8137.2008.02617.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Atmospheric nitrogen deposition can cause major declines in bryophyte abundance yet the physiological basis for such declines is not fully understood. Bryophyte physiological responses may also be sensitive bioindicators of both the impacts of, and recovery from, N deposition. Here, responses of tissue nutrients (nitrogen (N), phosphorus (P) and potassium (K): NPK), N and P metabolism enzymes (nitrate reductase and phosphomonoesterase), photosynthetic pigments, chlorophyll fluorescence, sclerophylly and percentage cover of two common bryophytes (Pseudoscleropodium purum and Rhytidiadelphus squarrosus) to long-term (11 yr) enhanced N deposition (+3.5 and +14 g N m(-2) yr(-1)) are reported in factorial combination with P addition. Recovery of responses 22 months after treatment cessation were also assessed. Enhanced N deposition caused up to 90% loss of bryophyte cover but no recovery was observed. Phosphomonoesterase activity and tissue N:P ratios increased up to threefold in response to N loading and showed clear recovery, particularly in P. purum. Smaller responses and recovery were also seen in all chlorophyll fluorescence measurements and altered photosynthetic pigment composition. The P limitation of growth appears to be a key mechanism driving bryophyte loss along with damage to photosystem II. Physiological measurements are more sensitive than measurements of abundance as bioindicators of N deposition impact and of recovery in particular.
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Affiliation(s)
- María Arróniz-Crespo
- University of Sheffield, Department of Animal and Plant Sciences, Western Bank, Sheffield, S10 2TN, UK.
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