 |
| Titel |
Impact of cloudiness on net ecosystem exchange of carbon dioxide in different types of forest ecosystems in China |
| VerfasserIn |
M. Zhang, G.-R. Yu, L.-M. Zhang, X.-M. Sun, X.-F. Wen, S.-J. Han, J.-H. Yan |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1726-4170
|
| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 7, no. 2 ; Nr. 7, no. 2 (2010-02-23), S.711-722 |
| Datensatznummer |
250004498
|
| Publikation (Nr.) |
 copernicus.org/bg-7-711-2010.pdf |
|
|
|
|
|
| Zusammenfassung |
| Clouds can significantly affect carbon exchange process between forest
ecosystems and the atmosphere by influencing the quantity and quality of
solar radiation received by ecosystem's surface and other environmental
factors. In this study, we analyzed the effects of cloudiness on net
ecosystem exchange of carbon dioxide (NEE) in a temperate broad-leaved
Korean pine mixed forest at Changbaishan (CBS) and a subtropical evergreen
broad-leaved forest at Dinghushan (DHS), based on the flux data obtained
during June–August from 2003 to 2006. The results showed that the response
of NEE of forest ecosystems to photosynthetically active radiation (PAR)
differed under clear skies and cloudy skies. Compared with clear skies, the
light-saturated maximum photosynthetic rate (Pec,max) at CBS under
cloudy skies during mid-growing season (from June to August) increased by
34%, 25%, 4% and 11% in 2003, 2004, 2005 and 2006, respectively.
In contrast, Pec,max of the forest ecosystem at DHS was higher under
clear skies than under cloudy skies from 2004 to 2006. When the clearness
index (kt) ranged between 0.4 and 0.6, the NEE reached its maximum at
both CBS and DHS. However, the NEE decreased more dramatically at CBS than
at DHS when kt exceeded 0.6. The results indicate that cloudy sky
conditions are beneficial to net carbon uptake in the temperate forest
ecosystem and the subtropical forest ecosystem. Under clear skies, vapor
pressure deficit (VPD) and air temperature increased due to strong light.
These environmental conditions led to greater decrease in gross ecosystem
photosynthesis (GEP) and greater increase in ecosystem respiration
(Re) at CBS than at DHS. As a result, clear sky conditions caused more
reduction of NEE in the temperate forest ecosystem than in the subtropical
forest ecosystem. The response of NEE of different forest ecosystems to the
changes in cloudiness is an important factor that should be included in
evaluating regional carbon budgets under climate change conditions. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|