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Contribution of soil moisture to seasonal and annual variations of soil CO 2 efflux in a humid cool‐temperate oak‐birch forest in central Japan
Author(s) -
KishimotoMo Ayaka Wenhong,
Yonemura Seiichiro,
Uchida Masaki,
Kondo Miyuki,
Murayama Shohei,
Koizumi Hiroshi
Publication year - 2015
Publication title -
ecological research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.628
H-Index - 68
eISSN - 1440-1703
pISSN - 0912-3814
DOI - 10.1007/s11284-015-1254-6
Subject(s) - environmental science , water content , temperate forest , ecosystem , moisture , deciduous , snow , soil science , temperate climate , hydrology (agriculture) , chemistry , ecology , biology , geology , geotechnical engineering , organic chemistry , geomorphology
Abstract To quantify the contribution of soil moisture to seasonal and annual variations in soil CO 2 efflux in a cool‐humid deciduous broadleaf forest, we measured soil CO 2 efflux during the snow‐free seasons of 2005–2008 using an automated chamber technique. This worked much better than manual chambers employing the same steady‐state through‐flow method. Soil CO 2 efflux (g C m −2 period −1 ) during the snow‐free season ranged from 979.8 ± 49.0 in 2005 to 1131.2 ± 56.6 in 2008 with a coefficient variation of 6.4 % among the 4 years. We established two‐parameter (soil temperature and moisture) empirical models, finding that while soil temperature and moisture explained 69–86 % and 10–13 % of the temporal variability, respectively. Soil moisture had the effect of modifying the temporal variability of soil CO 2 efflux, particularly during summer and early fall after episodic rainfall events; greater soil moisture enhanced soil CO 2 efflux in the surface soil layers. High soil moisture conditions did not suppress soil CO 2 efflux, leading to a positive correlation between normalized soil CO 2 efflux (ratio of the measured to predicted efflux using a temperature‐dependent Q 10 function) and soil moisture. Therefore, enhanced daily soil CO 2 efflux following heavy rainfall events could significantly reduce net ecosystem exchange (i.e. daily net ecosystem production) by 32 % on some days. Our results highlight the importance of precisely estimating the response of soil CO 2 efflux to changes in soil moisture following rainfall events when modeling seasonal carbon dynamics in response to climate change, even in humid monsoon regions.