 |
| Titel |
Drivers of methane uptake by montane forest soils in the Peruvian Andes |
| VerfasserIn |
Sam Jones, Torsten Diem, Lidia Huaraca Quispe, Adan Cahuana, Patrick Meir, Yit Teh |
| Konferenz |
EGU General Assembly 2016
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250121917
|
| Publikation (Nr.) |
 EGU/EGU2016-814.pdf |
|
|
|
|
|
| Zusammenfassung |
| The exchange of methane between the soils of humid tropical forests and the atmosphere is
relatively poorly documented. This is particularly true of montane settings where variations
between uptake and emission of atmospheric methane have been observed. Whilst most of
these ecosystems appear to function as net sinks for atmospheric methane, some act as
considerable sources. In regions like the Andes, humid montane forests are extensive and a
better understanding of the magnitude and controls on soil-atmosphere methane exchange is
required.
We report methane fluxes from upper montane cloud forest (2811 - 2962 m asl), lower
montane cloud forest (1532 - 1786 m asl), and premontane forest (1070 - 1088 m asl) soils in
south-eastern Peru. Between 1000 and 3000 m asl, mean annual air temperature and total
annual precipitation decrease from 24 ˚ C and 5000 mm to 12 ˚ C and 1700 mm. The study
region experiences a pronounced wet season between October and April. Monthly
measurements of soil-atmosphere gas exchange, soil moisture, soil temperature, soil oxygen
concentration, available ammonium and available nitrate were made from February 2011 in
the upper and lower montane cloud forests and July 2011 in the premontane forest to June
2013.
These soils acted as sinks for atmospheric methane with mean net fluxes for wet and dry
season, respectively, of -2.1 (0.2) and -1.5 (0.1) mg CH4 m−2 d−1 in the upper
montane forest; -1.5 (0.2) and -1.4 (0.1) mg CH4 m−2 d−1in the lower montane forest;
and -0.3 (0.2) and -0.2 (0.2) mg CH4 m−2 d−1 in the premontane forest. Spatial
variations among forest types were related to available nitrate and water-filled pore
space suggesting that nitrate inhibition of oxidation or constraints on the diffusional
supply of methane to methanotrophic communities may be important controls on
methane cycling in these soils. Seasonality in methane exchange, with weaker uptake
related to increased water-filled pore space and soil temperature during the wet
season, was only apparent in the upper montane forest. Differences in patterns
of soil-atmosphere methane exchange and environmental conditions here and in
previous studies of similar ecosystems allow us to speculate that the interaction
between soil structure and rainfall regimes may help explain observed variability. |
|
|
|
|
|
|