Drivers of atmospheric methane uptake by montane forest soils in the southern Peruvian Andes
The soils of tropical montane forests can act as sources or sinks of atmospheric methane (CH<sub>4</sub>). Understanding this activity is important in regional atmospheric CH<sub>4</sub> budgets given that these ecosystems account for substantial portions of the landscape in...
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2016-07-01
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| Series: | Biogeosciences |
| Online Access: | http://www.biogeosciences.net/13/4151/2016/bg-13-4151-2016.pdf |
| Summary: | The soils of tropical montane forests can act as sources or
sinks of atmospheric methane (CH<sub>4</sub>). Understanding this activity is
important in regional atmospheric CH<sub>4</sub> budgets given that these
ecosystems account for substantial portions of the landscape in mountainous
areas like the Andes. We investigated the drivers of net CH<sub>4</sub> fluxes
from premontane, lower and upper montane forests, experiencing a seasonal
climate, in south-eastern Peru. Between February 2011 and June 2013, these
soils all functioned as net sinks for atmospheric CH<sub>4</sub>. Mean (standard
error) net CH<sub>4</sub> fluxes for the dry and wet season were −1.6 (0.1) and
−1.1 (0.1) mg CH<sub>4</sub>-C m<sup>−2</sup> d<sup>−1</sup> in the upper montane forest,
−1.1 (0.1) and −1.0 (0.1) mg CH<sub>4</sub>-C m<sup>−2</sup> d<sup>−1</sup> in the lower
montane forest, and −0.2 (0.1) and −0.1
(0.1) mg CH<sub>4</sub>-C m<sup>−2</sup> d<sup>−1</sup> in the premontane forest. Seasonality in CH<sub>4</sub> exchange varied
among forest types with increased dry season CH<sub>4</sub> uptake only apparent
in the upper montane forest. Variation across these forests was best
explained by available nitrate and water-filled pore space indicating that
nitrate inhibition of oxidation or diffusional constraints imposed by
changes in water-filled pore space on methanotrophic communities may
represent important controls on soil–atmosphere CH<sub>4</sub> exchange. Net
CH<sub>4</sub> flux was inversely related to elevation; a pattern that differs to
that observed in Ecuador, the only other extant study site of
soil–atmosphere CH<sub>4</sub> exchange in the tropical Andes. This may result
from differences in rainfall patterns between the regions, suggesting that
attention should be paid to the role of rainfall and soil moisture dynamics
in modulating CH<sub>4</sub> uptake by the organic-rich soils typical of high-elevation tropical forests. |
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| ISSN: | 1726-4170 1726-4189 |