Nitrogen as a threat to European terrestrial biodiversity

Abstract

Nature of the problemBiodiversity is the variability among living organisms, from genes to the biosphere. Th e value of biodiversity is multifold, from preserving • the integrity of the biosphere as a whole, to providing food and medicines, to spiritual and aesthetic well-being. One of the major drivers of biodiversity loss in Europe is atmospheric deposition of reactive nitrogen (N • r ). ApproachesTh is chapter focuses on N • r impacts on European plant species diversity; in particular, the number and abundance of diff erent species in a given area, and the presence of characteristic species of sensitive ecosystems. We summarise both the scientifi c and the policy aspects of N • r impacts on diversity and identify, using a range of evidence, the most vulnerable ecosystems and regions in Europe. Key fi ndings / state of knowledgeReactive nitrogen impacts vegetation diversity through direct foliar damage, eutrophication, acidifi cation, and susceptibility to secondary • stress. Species and communities most sensitive to chronically elevated N • r deposition are those that are adapted to low nutrient levels, or are poorly buff ered against acidifi cation. Grassland, heathland, peatland, forest, and arctic/montane ecosystems are recognised as vulnerable habitats in Europe; other habitats may be vulnerable but are still poorly studied. It is not yet clear if diff erent wet-deposited forms of N • r (e.g. nitrate, NO 3 − versus ammonium, NH 4 + ) have diff erent eff ects on biodiversity. However, gaseous ammonia (NH 3 ) can be particularly harmful to vegetation, especially lower plants, through direct foliar damage. Th ere are some clear examples of reductions in faunal diversity that can be linked to N • r deposition, but overall, our knowledge of faunal eff ects is still limited. Changes to above-ground faunal communities probably occur primarily through changes in vegetation diversity, composition or structure. Evidence is strong that ecological communities respond to the accumulated pool of plant-available N in the soil. Th us the • cumulative load of enhanced N r impacting an ecosystem is probably highly important. Because of this response to cumulative inputs, it is likely that biodiversity has been in decline in Europe for many decades due to enhanced • N r deposition. Equally, full recovery in response to reduced N r deposition is likely to be slow, especially in highly impacted ecosystems. In some cases recovery may require management intervention. Exceedence of critical loads for nutrient nitrogen is linked to reduced plant species richness in a broad range of European ecosystems. • Major uncertainties/challengesIt is very likely that N • r deposition acts synergistically with other stressors, in particular climate change, acid deposition, and ground-level ozone; these synergies are poorly understood. Th e nature and rate of recovery of biodiversity from nitrogen pollution is not well understood. Th e optimal strategy to restore a habitat, • and exactly what this 'restored' habitat constitutes, are both hard ...

Assessment of uncertainties in greenhouse gas emission profiles of livestock sectors in Africa, Latin America and Europe

“…Expanding livestock sectors can contribute to greenhouse gas (GHG) emissions, agricultural land expansion and associated deforestation (Steinfeld et al 2006), surface water eutrophication (Seitzinger et al 2005;Boyer et al 2006), decrease in terrestrial biodiversity (Dise et al 2011) and nutrient imbalances (Smaling et al 2008;Menzi et al 2010). The global animal food chain, including land use change, contributes 14.5 % of the global anthropogenic GHG emissions, including carbon dioxide (CO 2 ), methane (CH 4 ) and nitrous oxide (N 2 O), expressed in CO 2 equivalents (CO 2 -eq; Gerber et al 2013).…”

The agrarian metabolism as a tool for assessing agrarian sustainability, and its application to Spanish agriculture (1960-2008)

“…NH 3 volatilized from cropland in 2008 (185 Gg N) was higher than the value for the same year estimated by the official Spanish N balance (MAPAMA 2017), but lower than the value estimated by SanzCobena et al (2014) using a more detailed approach. NH 3 has a short atmospheric lifetime and is usually deposited near its source, https://www.ecologyandsociety.org/vol23/iss1/art2/ contributing to the eutrophication of natural waters (Grizzetti et al 2011), increased N input into natural terrestrial ecosystems, causing biogeochemical imbalances (van Herk et al 2003), and increased susceptibility to stress and changes in soil and plant communities (Dise et al 2011). Nitrate leaching is related to the eutrophication of ground and surface watercourses and estuaries (Fowler et al 2013) and poses a recognized risk to human health.…”

Interactive effects of anthropogenic nitrogen enrichment and climate change on terrestrial and aquatic biodiversity

“…For plants, these are usually categorized into four mechanisms: eutrophication, acidification, direct damage, and through secondary factors Dise et al 2011;Pardo et al 2011a, b). Nitrogen is a commonly limiting resource for autotrophic plants, and excess amounts can lead to eutrophication of ecosystems, thus favoring fastgrowing species in terrestrial and aquatic systems.…”

“…Nitrogen is a commonly limiting resource for autotrophic plants, and excess amounts can lead to eutrophication of ecosystems, thus favoring fastgrowing species in terrestrial and aquatic systems. This increased growth can reduce light penetration at the soil layer (or underwater for submerged macrophytes) and reduce belowground nutrient availability for other species, leading to overall declines in biodiversity and shifts in species composition (Hautier et al 2009;Dise et al 2011). Nitrogen enrichment can also acidify soil and water, lead to losses of base cations from the soil, nutrient imbalances, and increases in toxic compounds in the soil (e.g., aluminum, Al 3? )…”