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Ammonia Emissions from Subalpine Forest and Mountain Grassland Soils in Rocky Mountain National Park
Author(s) -
Stratton Joshua J.,
Ham Jay,
Borch Thomas
Publication year - 2018
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2018.01.0023
Subject(s) - soil water , grassland , national park , environmental science , deposition (geology) , subalpine forest , alpine climate , ammonium , montane ecology , eutrophication , nitrogen , flux (metallurgy) , hydrology (agriculture) , ecosystem , environmental chemistry , ecology , chemistry , soil science , geology , nutrient , paleontology , geotechnical engineering , sediment , biology , organic chemistry
Atmospheric deposition of NH 3 and NH 4 + contributes to eutrophication within sensitive subalpine ecosystems of Rocky Mountain National Park (RMNP) in the United States. However, little is known about the local contribution of NH 3 from soils within the park. Thus, the goal of this study was to quantify and compare NH 3 emissions from intact soil cores sampled from a subalpine grassland and forest within RMNP. Cores were collected at 2‐wk intervals from 20 June 2011 to 12 Sept. 2011 and transferred to a laboratory chamber system for NH 3 flux measurements. Additionally, N wet deposition was monitored at the sampling location to investigate possible impacts on NH 3 soil emissions. The average quantifiable NH 3 emissions (with SDs) from intact soil cores analyzed in the laboratory (23°C) were 0.42 ± 0.30 mg NH 3 –N m −2 d −1 for grassland soil and 0.21 ± 0.03 mg NH 3 –N m −2 d −1 for forest soil ( p < 0.001). A mechanistic model was developed to estimate the impact of temperature on soil emissions using the chamber data and field‐site air temperatures. Average estimated NH 3 emissions from the field site over the study period were 0.21 and 0.082 mg NH 3 –N m −2 d −1 for grasslands and forests, respectively. Ammonium wet deposition was not correlated to short term reemission of NH 3 based on N isotope analysis. This work provides new information on the magnitude of NH 3 emissions from native subalpine soils, indicating that natural emissions are not likely major sources of NH 3 in the RMNP airshed. Core Ideas We assessed NH 3 emissions from native subalpine soils in the RMNP. NH 3 emissions from grassland and forest soils within RMNP were directly compared. NH 3 emissions from forest soils were significantly lower than grassland soils. Natural NH 3 emission from soils likely plays a minor role in NH 4 + wet deposition in the RMNP.