Soil greenhouse gas emissions and carbon budgeting in a short-hydroperiod floodplain wetland

被引:79
作者
Batson, Jackie [1 ]
Noe, Gregory B. [1 ]
Hupp, Cliff R. [1 ]
Krauss, Ken W. [2 ]
Rybicki, Nancy B. [1 ]
Schenk, Edward R. [1 ]
机构
[1] US Geol Survey, Natl Res Program, Reston, VA 22092 USA
[2] US Geol Survey, Natl Wetlands Res Ctr, Lafayette, LA USA
关键词
carbon; greenhouse gases; floodplain; riparian; geomorphology; hydrologic connectivity; COASTAL-PLAIN RIVERS; METHANE EMISSIONS; PHOSPHORUS MINERALIZATION; SEASONAL PATTERNS; DIOXIDE EXCHANGE; CH4; EMISSIONS; NITROUS-OXIDE; AMAZON RIVER; CO2; FLUXES; RESPIRATION;
D O I
10.1002/2014JG002817
中图分类号
X [环境科学、安全科学];
学科分类号
08 ; 0830 ;
摘要
Understanding the controls on floodplain carbon (C) cycling is important for assessing greenhouse gas emissions and the potential for C sequestration in river-floodplain ecosystems. We hypothesized that greater hydrologic connectivity would increase C inputs to floodplains that would not only stimulate soil C gas emissions but also sequester more C in soils. In an urban Piedmont river (151km(2) watershed) with a floodplain that is dry most of the year, we quantified soil CO2, CH4, and N2O net emissions along gradients of floodplain hydrologic connectivity, identified controls on soil aerobic and anaerobic respiration, and developed a floodplain soil C budget. Sites were chosen along a longitudinal river gradient and across lateral floodplain geomorphic units (levee, backswamp, and toe slope). CO2 emissions decreased downstream in backswamps and toe slopes and were high on the levees. CH4 and N2O fluxes were near zero; however, CH4 emissions were highest in the backswamp. Annual CO2 emissions correlated negatively with soil water-filled pore space and positively with variables related to drier, coarser soil. Conversely, annual CH4 emissions had the opposite pattern of CO2. Spatial variation in aerobic and anaerobic respiration was thus controlled by oxygen availability but was not related to C inputs from sedimentation or vegetation. The annual mean soil CO2 emission rate was 1091gCm(-2)yr(-1), the net sedimentation rate was 111gCm(-2)yr(-1), and the vegetation production rate was 240gCm(-2)yr(-1), with a soil C balance (loss) of -338gCm(-2)yr(-1). This floodplain is losing C likely due to long-term drying from watershed urbanization.
引用
收藏
页码:77 / 95
页数:19
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