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Spatial variability of soil N 2 O and CO 2 fluxes in different topographic positions in a tropical montane forest in Kenya
Author(s) -
AriasNavarro C.,
DíazPinés E.,
Klatt S.,
Brandt P.,
Rufino M. C.,
ButterbachBahl K.,
Verchot L. V.
Publication year - 2017
Publication title -
journal of geophysical research: biogeosciences
Language(s) - English
Resource type - Journals
eISSN - 2169-8961
pISSN - 2169-8953
DOI - 10.1002/2016jg003667
Subject(s) - environmental science , spatial variability , biogeochemical cycle , greenhouse gas , soil water , vegetation (pathology) , atmospheric sciences , nitrous oxide , soil carbon , montane ecology , carbon dioxide , ecosystem , tropical forest , soil science , hydrology (agriculture) , ecology , environmental chemistry , chemistry , geology , medicine , statistics , mathematics , pathology , biology , geotechnical engineering
Quantifying and understanding the small‐scale variability of nitrous oxide (N 2 O) and carbon dioxide (CO 2 ) emission are essential for reporting accurate ecosystem greenhouse gas budgets. The objective of this study was to evaluate the spatial pattern of soil CO 2 and N 2 O emissions and their relation to topography in a tropical montane forest. We measured fluxes of N 2 O and CO 2 from 810 sampling locations across valley bottom, midslope, and ridgetop positions under controlled laboratory conditions. We further calculated the minimum number of samples necessary to provide best estimates of soil N 2 O and CO 2 fluxes at the plot level. Topography exhibited a major influence on N 2 O emissions, with soils at midslope position emitting significantly less than at ridgetops and valley bottoms, but no consistent effect of topography on soil CO 2 emissions was found. The high spatial variation of N 2 O and CO 2 fluxes was further increased by changes in vegetation and soil properties resulting from human disturbance associated with charcoal production. Soil N 2 O and CO 2 fluxes showed no spatial pattern at the plot level, with “hot spots” strongly contributing to the total emissions (10% of the soil cores represented 73 and 50% of the total N 2 O and CO 2 emissions, respectively). Thus, a large number of samples are needed to obtain robust estimates of N 2 O and CO 2 fluxes. Our results highlight the complex biogeochemical cycling in tropical montane forests, and the need to carefully address it in research experiments to robustly estimate soil CO 2 and N 2 O fluxes at the ecosystem scale.