DOI: 10.1002/2015GB005298
Scopus记录号: 2-s2.0-84964195332
论文题名: Nitrogen trace gas fluxes from a semiarid subtropical savanna under woody legume encroachment
作者: Soper F ; M ; , Boutton T ; W ; , Groffman P ; M ; , Sparks J ; P
刊名: Global Biogeochemical Cycles
ISSN: 8866236
出版年: 2016
卷: 30, 期: 5 起始页码: 614
结束页码: 628
语种: 英语
英文关键词: N2O
; NH3
; NOy
; Prosopis
; temperature
; wetting dynamics
Scopus关键词: abiotic factor
; air quality
; emission
; gas exchange
; legume
; nitrous oxide
; rainfall
; savanna
; semiarid region
; shrub
; suboxic conditions
; subtropical region
; temperature
; topography
; trace gas
; wetting
; Texas
; United States
; Prosopis
; Prosopis glandulosa
英文摘要: Savanna ecosystems are a major source of nitrogen (N) trace gases that influence air quality and climate. These systems are experiencing widespread encroachment by woody plants, frequently associated with large increases in soil N, with no consensus on implications for trace gas emissions. We investigated the impact of encroachment by N-fixing tree Prosopis glandulosa on total reactive N gas flux (Nt = NO + N2O + NOy + NH3) from south Texas savanna soils over 2 years. Contrary to expectations, upland Prosopis groves did not have greater Nt fluxes than adjacent unencroached grasslands. However, abiotic conditions (temperature, rainfall, and topography) were strong drivers. Emissions from moist, low-lying Prosopis playas were up to 3 times higher than from Prosopis uplands. Though NO dominated emissions, NH3 and NOy (non-NO oxidized N) comprised 12–16% of the total summer N flux (up to 7.9 µg N m−2 h−1). Flux responses to soil wetting were temperature dependent for NO, NH3, and NOy: a 15 mm rainfall event increased flux 3-fold to 22-fold after 24 h in summer but had no effect in winter. Repeated soil wetting reduced N flux responses, indicating substrate depletion as a likely control. Rapid (<1 min) increases in NO emissions following wetting of dry soils suggested that abiotic chemodenitrification contributes to pulse emissions. We conclude that temperature and wetting dynamics, rather than encroachment, are primary drivers of N flux from these upland savannas, with implications for future emission patterns under altered precipitation regimes. ©2016. American Geophysical Union. All Rights Reserved. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/77859
Appears in Collections: 气候变化事实与影响
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作者单位: Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY, United States; Department of Ecosystem Science and Management, Texas A&M University, College Station, TX, United States; Cary Institute of Ecosystem Studies, Millbrook, NY, United States
Recommended Citation:
Soper F,M,, Boutton T,et al. Nitrogen trace gas fluxes from a semiarid subtropical savanna under woody legume encroachment[J]. Global Biogeochemical Cycles,2016-01-01,30(5)