Protecting Resources on Federal Lands: Implications of Critical Loads for Atmospheric Deposition of Nitrogen and Sulfur

Porter, Ellen; Blett, Tamara; Potter, Deborah Ulinski; Huber, Cindy M.

doi:10.1641/0006-3568(2005)055[0603:profli]2.0.co;2

Cited by 98 publications

(69 citation statements)

References 36 publications

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“…Critical loads, which have been widely used by environmentalists to assess the impacts of pollutants on ecosystems, are generally defined as the minimum input of a pollutant that causes a significant ''harmful effect'' on a sensitive ecological indicator (Bobbink and Roelofs 1995;Bowman et al 2006Bowman et al , 2012Porter et al 2005). The N critical load for changes in vegetation is defined as the N input level below which no biotic change (such as plant cover, biomass, or species composition) would occur (Bowman et al 2006).…”

Section: Introductionmentioning

confidence: 99%

Nitrogen Critical Loads for an Alpine Meadow Ecosystem on the Tibetan Plateau

Zong

Shi

Song

et al. 2015

Environmental Management

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Increasing atmospheric nitrogen (N) deposition has the potential to alter plant diversity and thus the function and stability of terrestrial ecosystems. N-limited alpine ecosystems are expected to be particularly susceptible to increasing N deposition. However, little is known about the critical loads and saturation thresholds of ecosystem responses to increasing N deposition on the Tibetan Plateau, despite its importance to ecosystem management. To evaluate the N critical loads and N saturation thresholds in an alpine ecosystem, in 2010, we treated an alpine meadow with five levels of N addition (0, 10, 20, 40, and 80 kg N ha -1 year -1 ) and characterized plant and soil responses. The results showed that plant species richness and diversity index did not statistically vary with N addition treatments, but they both changed with years. N addition affected plant cover and aboveground productivity, especially for grasses, and soil chemical features. The N critical loads and saturation thresholds, in terms of plant cover and biomass change at the community level, were 8.8-12.7 and 50 kg N ha -1 -year -1 (including the ambient N deposition rate), respectively. However, pronounced changes in soil inorganic N and net N mineralization occurred under the 20 and 40 kg N ha -1 year -1 treatments. Our results indicate that plant community cover and biomass are more sensitive than soil to increasing N inputs. The plant community composition in alpine ecosystems on the Qinghai-Tibetan Plateau may change under increasing N deposition in the future.

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Section: Introductionmentioning

confidence: 99%

Nitrogen Critical Loads for an Alpine Meadow Ecosystem on the Tibetan Plateau

Zong

Shi

Song

et al. 2015

Environmental Management

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“…Although nitrogen is an essential and often limiting element for ecosystems, increases in N r deposition resulting from increased emissions have raised concerns around the world due to its adverse environmental impacts, including decreased biological diversity, increased soil acidification, and lake eutrophication (5)(6)(7)(8)(9). Critical loads (CLs) have been widely used to quantify levels of N r deposition that ecosystems can sustain without significant harmful effects (10,11). Twenty-four of the 45 national parks in the contiguous United States were estimated to receive N r deposition in 2013 exceeding the local CL (12).…”

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confidence: 99%

Increasing importance of deposition of reduced nitrogen in the United States

Schichtel

Walker

et al. 2016

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

354

253

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Rapid development of agriculture and fossil fuel combustion greatly increased US reactive nitrogen emissions to the atmosphere in the second half of the 20th century, resulting in excess nitrogen deposition to natural ecosystems. Recent efforts to lower nitrogen oxides emissions have substantially decreased nitrate wet deposition. Levels of wet ammonium deposition, by contrast, have increased in many regions. Together these changes have altered the balance between oxidized and reduced nitrogen deposition. Across most of the United States, wet deposition has transitioned from being nitrate-dominated in the 1980s to ammonium-dominated in recent years. Ammonia has historically not been routinely measured because there are no specific regulatory requirements for its measurement. Recent expansion in ammonia observations, however, along with ongoing measurements of nitric acid and fine particle ammonium and nitrate, permit new insight into the balance of oxidized and reduced nitrogen in the total (wet + dry) US nitrogen deposition budget. Observations from 37 sites reveal that reduced nitrogen contributes, on average, ∼65% of the total inorganic nitrogen deposition budget. Dry deposition of ammonia plays an especially key role in nitrogen deposition, contributing from 19% to 65% in different regions. Future progress toward reducing US nitrogen deposition will be increasingly difficult without a reduction in ammonia emissions.ammonia | dry deposition | wet deposition | nitrogen oxides | agriculture

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“…Shifts in diatom community composition provide early indications of ecological perturbations, whether by acidification (Charles et al 1990), eutrophication (Hall et al 1997), or climate change (Smol et al 2005). Because of the documented sensitivity of diatoms to environmental change, they have been used to define critical loads of acidity (Battarbee et al 1996) and nitrogen enrichment (Baron 2006) to surface waters, with the critical load defined as the threshold below which observable ecological effects do not occur (Porter et al 2005).…”

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confidence: 99%

Critical Nitrogen Deposition Loads in High-elevation Lakes of the Western US Inferred from Paleolimnological Records

Saros

Clow

Blett

et al. 2010

Water Air Soil Pollut

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Critical loads of nitrogen (N) from atmospheric deposition were determined for alpine lake ecosystems in the western US using fossil diatom assemblages in lake sediment cores. Changes in diatom species over the last century were indicative of N enrichment in two areas, the eastern Sierra Nevada, starting between 1960 and 1965, and the Greater Yellowstone Ecosystem, starting in 1980. In contrast, no changes in diatom community structure were apparent in lakes of Glacier National Park. To determine critical N loads that elicited these community changes, we modeled wet nitrogen deposition rates for the period in which diatom shifts first occurred in each area using deposition data spanning from 1980 to 2007. We determined a critical load of 1.4 kg N ha −1 year −1 wet N deposition to elicit key nutrient enrichment effects on diatom communities in both the eastern Sierra Nevada and the Greater Yellowstone Ecosystem.

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Protecting Resources on Federal Lands: Implications of Critical Loads for Atmospheric Deposition of Nitrogen and Sulfur

Abstract: Critical loads are a potentially important tool for protecting ecosystems from atmospheric deposition

Cited by 98 publications

References 36 publications

Nitrogen Critical Loads for an Alpine Meadow Ecosystem on the Tibetan Plateau

Nitrogen Critical Loads for an Alpine Meadow Ecosystem on the Tibetan Plateau

Increasing importance of deposition of reduced nitrogen in the United States

Critical Nitrogen Deposition Loads in High-elevation Lakes of the Western US Inferred from Paleolimnological Records

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