Effect of Increased N deposition on nitrous oxide, methane and carbon dioxide fluxes from unmanaged forest and grassland communities in Michigan

• Published in: Biogeochemistry Vol. 79; no. 3; pp. 315 - 337
• Main Authors: Ambus, P, Robertson, G.P
• Format: Journal Article
• Language: English
• Published: Heidelberg Springer 01.07.2006; Springer Nature B.V
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; atmospheric deposition; Biological and medical sciences; Biological fertilization; Carbon dioxide; Coniferous forests; Deciduous forests; Deposition; Earth sciences; Earth, ocean, space; Efflux; Emissions; Engineering and environment geology. Geothermics; Exact sciences and technology; Fertilization; Fluxes; Forest soils; Forests; Fundamental and applied biological sciences. Psychology; gas emissions; gas exchange; Grasses; Grassland soils; Grasslands; Growing season; Methane; methane production; methanogens; Michigan; Nitrogen; Nitrous oxide; Oxidation; Pollution, environment geology; Soil; Soil air; soil bacteria; soil microorganisms; soil pollution; Soil respiration; Soils; Surficial geology; Synecology; Terrestrial ecosystems; Tillage; Trace gases; Uptake; Vegetation type; Michigan; United States; United States > US; atmosphere; experimental studies; Grassland; atmospheric emission; nitrous oxide; vegetation; respiration; North America; tillage; greenhouse gas; forest soils; grasslands; Trace gas; soils; Successional Community; laboratory studies; N-deposition; carbon dioxide; fertilization; nitrogen; oxidation; soil horizons; concentration; forests; ecosystems; methane; Forest; atmosphere-soil interaction; statistical analysis
• ISSN: 0168-2563; 1573-515X
• DOI: 10.1007/s10533-005-5313-x

Atmospheric nitrogen deposition is anticipated to increase over the next decades with possible implications for future forest-atmosphere interactions. Increased soil N₂O emissions, depressed CH₄ uptake and depressed soil respiration CO₂ loss is considered a likely response to increased N deposition. This study examined fluxes of N₂O, CH₄ and CO₂ over two growing seasons from soils in unmanaged forest and grassland communities on abandoned agricultural areas in Michigan. All sites were subject to simulated increased N-deposition in the range of 1-3 g N m⁻² annually. Nitrous oxide fluxes and soil N concentrations in coniferous and grassland sites were on the whole unaffected by the increased N-inputs. It is noteworthy though that N₂O emissions increased three-fold in the coniferous sites in the first growing season in response to the low N treatment, although the response was barely significant (p < 0.06). In deciduous forests, we observed increased levels of soil mineral N during the second year of N fertilization, however N₂O fluxes did not increase. Rates of methane oxidation were similar in all sites with no affect of field N application. Likewise, we did not observe any changes in soil CO₂ efflux in response to N additions. The combination of tillage history and vegetation type was important for the trace gas fluxes, i.e. soil CO₂ efflux was greater in successional grassland sites compared with the forested sites and CH₄ uptake was reduced in post-tillage coniferous- and successional sites compared with the old-growth deciduous site. Our results indicate that short-term increased N availability influenced individual processes linked to trace gas turnover in the soil independently from the ecosystem N status. However, changes in whole system fluxes were not evident and were very likely mediated by competitive N uptake processes.