Premium
Fluxes of CH 4 and CO 2 from soil and termite mounds in south Sudanian savanna of Burkina Faso (West Africa)
Author(s) -
Brümmer Christian,
Papen Hans,
Wassmann Reiner,
Brüggemann Nicolas
Publication year - 2009
Publication title -
global biogeochemical cycles
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.512
H-Index - 187
eISSN - 1944-9224
pISSN - 0886-6236
DOI - 10.1029/2008gb003237
Subject(s) - soil respiration , dry season , sorghum , environmental science , soil water , wet season , sink (geography) , tropics , crop , agronomy , seasonality , ecosystem , hydrology (agriculture) , geography , forestry , ecology , biology , soil science , geology , cartography , geotechnical engineering
The contribution of West African savanna ecosystems to global greenhouse gas budgets is highly uncertain. In this study we quantified soil‐atmosphere CH 4 and CO 2 fluxes in the southwest of Burkina Faso from June to September 2005 and from April to September 2006 at four different agricultural fields planted with sorghum ( n = 2), cotton, and peanut and at a natural savanna site with termite ( Cubitermes fungifaber ) mounds. During the rainy season both CH 4 uptake and CH 4 emission were observed in the savanna, which was on average a CH 4 source of 2.79 and 2.28 kg CH 4 ‐C ha −1 a −1 in 2005 and 2006, respectively. The crop sites were an average CH 4 sink of −0.67 and −0.70 kg CH 4 ‐C ha −1 a −1 in the 2 years, without significant seasonal variation. Mean annual soil respiration ranged between 3.86 and 5.82 t CO 2 ‐C ha −1 a −1 in the savanna and between 2.50 and 4.51 t CO 2 ‐C ha −1 a −1 at the crop sites. CH 4 emission from termite mounds was 2 orders of magnitude higher than soil CH 4 emissions, whereas termite CO 2 emissions were of the same order of magnitude as soil CO 2 emissions. Termite CH 4 and CO 2 release in the savanna contributed 8.8% and 0.4% to the total soil CH 4 and CO 2 emissions, respectively. At the crop sites, where termite mounds had been almost completely removed because of land use change, termite fluxes were insignificant. Mound density‐based upscaling of termite CH 4 fluxes resulted in a global termite CH 4 source of 0.9 Tg a −1 , which corresponds to 0.15% of the total global CH 4 budget of 582 Tg a −1 , hence significantly lower than those obtained previously by biomass‐based calculations. This study emphasizes that land use change, which is of high relevance in this region, has particularly affected soil CH 4 fluxes in the past and might still do so in the future.