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| Titel |
Methane fluxes from a wet puna ecosystem in the Peruvian Andes |
| VerfasserIn |
Sam Jones, Torsten Diem, Lidia Priscila Huaraca Quispe, Adan Ccahuana, Julian Quispe, Patrick Meir, Yit Arn Teh |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250086760
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| Publikation (Nr.) |
 EGU/EGU2014-681.pdf |
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| Zusammenfassung |
| Discrepancies exist between top-down and bottom-up estimates of the tropical
South American atmospheric methane budget. This suggests that current source-sink
inventories fail to adequately characterise the landscapes of the region. This may be
particularly true of Andean environments where very few field observations have been
made. The high tropical Andes, between tree and permanent snow-lines, is home to
diverse grass, shrub and giant rosette dominated ecosystems known variously from
Venezuela to northern Chile and Argentina as paramo, jalca and puna. In humid regions
these are characterised by wet, organic-rich mineral soils, peat-forming wetlands
and shallow lakes. Such conditions are likely to promote methane production and
potentially represent a regionally significant source to the atmosphere that should be
considered.
We report on methane fluxes from a bunch-grass dominated puna habitat at 3500 m above
sea level in south-eastern Peru. Mean annual temperature and precipitation are 11 °C and
2500 mm, respectively. Temperature is aseasonal but experiences considerable diurnal
variations with overnight frosting common-place. In contrast, rainfall is intensely episodic
and has a pronounced wet season between September and March. Sampling encompassed a
range of topographic features, such as grassland on freely draining, gently inclined or steep
slopes and depressions containing bogs, over a 3 ha ridge to basin transition. Monthly
sampling was carried out between January 2011 and June 2013 to investigate seasonal
variability in methane fluxes. Intensive sampling campaigns were conducted to investigate
spatial and short-term variations on a daily basis in two nine-day campaigns during wet and
dry season.
The site was a net source of methane to the atmosphere during the period of study.
Methane fluxes were dominated by emissions from bogs, whereas, freely draining grassland
exhibited weak source or marginal sink activity. Temporal variations were most notable at the
seasonal scale with fluxes during the wet season almost an order of magnitude greater than
those of the dry season. Mean emissions from bogs during wet and dry season were 85.0
(15.0) and 10.0 (2.0) mg C-CH4 m-2 d-1, respectively. Similarly, mean fluxes in the
grassland were 0.4 (0.7) and -0.05 (0.6) mg C-CH4 m-2 d-1. These data highlight the
importance of considering such Andean highlands in landscape scale source-sink
inventories. In this respect, understanding the influence of differences in climatic
regime found across the Andes and determining the areal extent of topographic
hotspots driving methane emissions within these environments are key challenges. |
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