 |
| Titel |
Soil methane and CO2 fluxes in rainforest and rubber plantations |
| VerfasserIn |
Rong Lang, Sergey Blagodatsky, Stefanie Goldberg, Jianchu Xu |
| Konferenz |
EGU General Assembly 2017
|
| Medientyp |
Artikel
|
| Sprache |
en
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250145942
|
| Publikation (Nr.) |
 EGU/EGU2017-9924.pdf |
|
|
|
|
|
| Zusammenfassung |
| Expansion of rubber plantations in South-East Asia has been a land use transformation trend
leading to losses of natural forest cover in the region. Besides impact on ecosystem carbon
stocks, this conversion influences the dynamics of greenhouse gas fluxes from soil driven by
microbial activity, which has been insufficiently studied. Aimed to understand how land
use change affects the soil CO2 and CH4 fluxes, we measured surface gas fluxes,
gas concentration gradient, and 13C signature in CH4 and soil organic matter in
profiles in a transect in Xishuangbanna, including a rainforest site and three rubber
plantation sites with age gradient. Gas fluxes were measured by static chamber
method and open chamber respiration system. Soil gases were sampled from installed
gas samplers at 5, 10, 30, and 75cm depth at representative time in dry and rainy
season.
The soil CO2 flux was comparable in rainforest and old rubber plantations, while
young rubber plantation had the lowest rate. Total carbon content in the surface
soil well explained the difference of soil CO2 flux between sites. All sites were
CH4 sinks in dry season and uptake decreased in the order of rainforest, old rubber
plantations and young rubber plantation. From dry season to rainy season, CH4
consumption decreased with increasing CH4 concentration in the soil profile at all
depths. The enrichment of methane by 13CH4 shifted towards to lowerδ13C, being
the evidence of enhanced CH4 production process while net surface methane flux
reflected the consumption in wet condition. Increment of CH4 concentration in the
profile from dry to rainy season was higher in old rubber plantation compared to
rainforest, while the shifting of δ13CH4 was larger in rainforest than rubber sites.
Turnover rates of soil CO2 and CH4 suggested that the 0-5 cm surface soil was
the most active layer for gaseous carbon exchange. δ13C in soil organic matter
and soil moisture increased from rainforest, young rubber plantation to old rubber
plantations.
Conversion the forest into rubber plantation decreased soil respiration in young plantation
and it recovered during rubber development. However, the CH4consumption by tropical
upland forest soil decreased in converted rubber plantations of all ages, with more decrement
in old plantation. Change forest into rubber plantations weakened the soil function as CH4
sink. |
|
|
|
|
|
|