Assessing nitrogen deposition and chemistry in mountainous regions of Olympic National Park and North Cascades National Park Service Complex, Pacific Northwest, USA.
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引用次数: 0
Abstract
Anthropogenic nitrogen (N) deposition (Ndep) can disrupt ecosystem dynamics, yet its spatial distribution and chemical composition in mountainous regions remains poorly understood. Accurate measurements of Ndep are needed to determine N critical loads and where deposition levels are expected to cause harm to ecosystem function. Epiphytic lichens can provide direct estimates of Ndep and insight into emission sources for remote mountainous areas where instrumented monitoring sites are not feasible and air quality models have a high degree of uncertainty. We used lichens to assess patterns of Ndep amounts and chemistry at North Cascades National Park Service Complex ('North Cascades') and Olympic National Park ('Olympic'). Lichen %N indicate rates of Ndep below N critical loads; our results contrast with air quality models that predict critical load exceedance in many areas. Lichen δ15N indicated a dominance of reduced N in Ndep suggesting significant contributions from NHx emission sources. Lowland areas adjacent to urban corridors exhibited the highest proportions of reduced N in Ndep. Current policies target oxidized N from fossil fuel combustion, but not reduced N, causing an increase in the reduced:oxidized ratio in Ndep. Species-specific responses to these changes could alter biodiversity, community structure, and ecosystem processes over time. Our study underscores the importance of fine-scale assessments of Ndep and deposition chemistry, particularly in ecologically sensitive mountainous regions.
期刊介绍:
Oecologia publishes innovative ecological research of international interest. We seek reviews, advances in methodology, and original contributions, emphasizing the following areas:
Population ecology, Plant-microbe-animal interactions, Ecosystem ecology, Community ecology, Global change ecology, Conservation ecology,
Behavioral ecology and Physiological Ecology.
In general, studies that are purely descriptive, mathematical, documentary, and/or natural history will not be considered.