Experimental Assessment of the Effects of Nitrogen Addition Under Hay- Cutting and Aftermath Grazing on the Vegetation of Meadows on a Somerset Peat Moor

Mountford, J. O.; Lakhani, K. H.; Kirkham, F. W.

doi:10.2307/2404634

Cited by 137 publications

(96 citation statements)

References 14 publications

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“…The species change points predominately are at the lower end of the N deposition gradient: one-third occur below the lower boundary of the currently established critical load for this habitat, and a similar number is within the critical load range. Independent evidence of sensitivity to N deposition exists for many of these species, such as Hypericum pulchrum (11), Plantago lanceolata (16,17), Hylocomium splendens (11,18,19), Achillea millefolium (20), and Succisa pratensis (21,22). Most of the species that decline in cover are forbs, and this finding agrees with studies showing this functional group to be particularly sensitive to N deposition (12).…”

Section: Resultssupporting

confidence: 72%

Impact of nitrogen deposition at the species level

Payne

Dise

Stevens

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

126

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In Europe and, increasingly, the rest of the world, the key policy tool for the control of air pollution is the critical load, a level of pollution below which there are no known significant harmful effects on the environment. Critical loads are used to map sensitive regions and habitats, permit individual polluting activities, and frame international negotiations on transboundary air pollution. Despite their fundamental importance in environmental science and policy, there has been no systematic attempt to verify a critical load with field survey data. Here, we use a large dataset of European grasslands along a gradient of nitrogen (N) deposition to show statistically significant declines in the abundance of species from the lowest level of N deposition at which it is possible to identify a change. Approximately 60% of species change points occur at or below the range of the currently established critical load. If this result is found more widely, the underlying principle of no harm in pollution policy may need to be modified to one of informed decisions on how much harm is acceptable. Our results highlight the importance of protecting currently unpolluted areas from new pollution sources, because we cannot rule out ecological impacts from even relatively small increases in reactive N deposition.plant ecology | Threshold Indicator Taxon Analysis | gradient survey S ince the 1980s, the key policy tool for the control of pollution in Europe has been the critical load (1). A critical load is defined as a "quantitative estimate of an exposure to one or more pollutants below which significant harmful effects on specified sensitive elements of the environment do not occur according to present knowledge" (1). Empirical critical load values are currently set for pollutants and habitats based primarily on pollution addition experiments and expert judgment, and they were most recently revised in 2010 (2). Critical loads have a central role in pollution management and are used for mapping pollution impacts, controlling and permitting individual pollution sources, and framing international negotiations on transboundary air pollution. They have recently been applied in the United States (3) and Canada (4), and they are under active consideration and development in many parts of the developing world (5).Embedded in the critical load concept is the idea that it is possible to define a level of pollution that does not harm the natural environment. We test this concept for the deposition of reactive nitrogen (N). N deposition is recognized as one of the most serious pollution threats to global ecosystems (6), and it is ranked among the top five drivers of global biodiversity loss (7). Current critical loads for N deposition are primarily based on N addition experiments, which are valuable for identifying cause-effect relationships but have some limitations. Many experiments are located in regions with high ambient N deposition (often above the established critical load) (8) and use elevated N loads with few treatments over rela...

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Section: Resultssupporting

confidence: 72%

Impact of nitrogen deposition at the species level

Payne

Dise

Stevens

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

126

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“…Further to this, species richness of vascular plants has been found to decrease in response to N deposition in a number of experimental studies (e.g. Bobbink et al, 1998;Clark and Tilman, 2008;Mountford et al, 1993).…”

Section: Introductionmentioning

confidence: 95%

“…There is a growing body of evidence from both experiments and surveillance studies that suggest that increases in nitrogen have a negative effect on species richness and composition (e.g. Mountford et al, 1993;Wilson et al, 1995; Published by Copernicus Publications on behalf of the European Geosciences Union. Maskell et al, 2010;Dupré et al, 2010;Smart et al, 2004;Van den Berg et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

Impacts of nitrogen deposition on vascular plants in Britain: an analysis of two national observation networks

et al. 2011

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Abstract. Large areas of Great Britain currently have nitrogen (N) deposition at rates which exceed the thresholds above which there is risk of damage to sensitive components of the ecosystem (critical loads). Previous studies have focussed primarily on the relationship of species richness to nitrogen, whereas here we look at individual species. We used data from two national observation networks over Great Britain to examine the response of individual vascular plant species to N in acid grasslands, calcareous grasslands and heathlands. Presence absence records of individual species, along with mean Ellenberg N scores, within 10 km hectads were modelled against N deposition whilst at the same time controlling for the effects of climate, land use and sulphur deposition using generalised additive models. Ellenberg N showed a significant increase with increasing N deposition in almost all habitats across both surveys indicating increased fertility. Many individual species showed strong relationships with N deposition and clear negative trends in species prevalence to increasing nitrogen were found in all habitats. A number of these species were either habitat dominants or possessed traits known to be influential in controlling ecosystem function. Many community dominants showing significant negative relationships with N deposition highlight a potentially significant loss of function. Some species that Correspondence to: P. A. Henrys (pehn@ceh.ac.uk) showed negative relationships to N showed signs of decline at low levels, far below the current critical load levels. Some species also showed continuous changes as N deposition levels rose above the current critical load values. This work contributes to the growing evidence base suggesting species level impacts at low N deposition values.

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“…The key drivers that influence the floristic composition of such floodplain meadows are well known and researched, and include the hydrological regime, the mesotrophic soil nutrient conditions and nutrient flows associated with river silt delivered by flooding patterns, and the meadow management regime (Mountford et al 1993(Mountford et al , 1996McDonald, 2001;Gowing et al, 2002Gowing et al, , 2005Crichley et al, 2007). The broad lines of traditional meadow management regimes and the impact of particular management operations on the grassland sward and species composition are also wellknown and researched (Benstead, 1997;Crofts and Jefferson, 1999;McDonald, 2001;Gowing et al, 2002).…”

Section: Introductionmentioning

confidence: 99%

The threat of abandonment in socio-ecological landscapes: Farmers’ motivations and perspectives on high nature value grassland conservation

McGinlay

Gowing

Budds

2017

Environmental Science & Policy

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Future sustainability of the conservation management of socio-ecological landscapes is typically reliant on on-going agricultural management. Such management may be threatened by changes in the drivers of management and the fragility of the stakeholder networks that deliver management. This study examined evidence for the risk of abandonment in a series of case study high nature value (HNV) grassland sites. The work found that the motivation of farmers to participate in the conservation management was typically limited and often marginal. Landowners and conservation stakeholders who relied on partner farmers to manage such sites often struggled to recruit and retain their help, leading to intermittent turnover in managing farmers and to some sites being under-managed. A trend towards greater financial incentivisation of farmers was evident, which policy-makers responsible for agri-environment schemes should note, and elsewhere some conservation organisations were seen to be bringing grassland management in-house. Primary reasons for farmer turnover and difficulty of recruitment included a lack of candidate farmers in the local landscape, and the marginal and fluctuating economics of grassland management. Farmers' motivations to participate in conservation management of such systems may continue to weaken and abandonment may therefore become a significant risk to the successful conservation of such systems. Conservation stakeholders need to foster good relations with their farmer-manager partners and not further depress their limited motivations to participate, as well as consider carefully whether farmer stakeholders are being adequately compensated for their efforts. Highlights Abandonment is a key risk to the management of some socio-ecological landscapes  Risks result from the difficulty in recruiting and retaining managing farmers  Farmers' motivations to participate are limited by marginal economic benefits  Trend towards increased financial incentivisation of farmers to improve retention

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Experimental Assessment of the Effects of Nitrogen Addition Under Hay- Cutting and Aftermath Grazing on the Vegetation of Meadows on a Somerset Peat Moor

Cited by 137 publications

References 14 publications

Impact of nitrogen deposition at the species level

Impact of nitrogen deposition at the species level

Impacts of nitrogen deposition on vascular plants in Britain: an analysis of two national observation networks

The threat of abandonment in socio-ecological landscapes: Farmers’ motivations and perspectives on high nature value grassland conservation

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