We estimated the inter-annual variation in soil CO2 efflux in a cool-temperate oak-birch forest in central Japan. CO2 effluxes from the soil surface during the snow-free season and from the snow surface during the snow-covered season were measured using an open-flow infrared gas analyzer method from December 1994 to December 1995. Climatic conditions in 1995 were significantly colder than the 22-year mean; this decreased observed values of daily CO2 efflux and resulting in different temperature response of CO2 efflux (estimated on the basis of the annual Q10 function) compared with the Q10 function derived from measured effluxes obtained at the same site and with the same method in normal, warmer years from 1999-2002. This suggests that empirical models such as annual Q 10 function must be parameterized for the target year before they can be used to estimate annual soil CO2 efflux, especially during periods of abnormal climatic conditions. Estimated annual values of soil CO 2 efflux from 1994-2002, based on the Q10 functions derived from annual datasets for 1995 (an abnormally cold year) and 1999-2002 (normal warm years), ranged from 597 to 793 g C m-2 y-1, with a mean ±SD of 713±71 g C m-2 y-1. The annual soil CO2 efflux in 1995, an abnormally cold year, was 16% lower than the mean for the 1994-2002 period, whereas efflux in a warm El Niño year (1998) was 11% higher than the mean. This suggests the presence of a large inter-annual variability in the annual soil CO2 efflux in this forest.
|ジャーナル||Phyton - Annales Rei Botanicae|
|出版ステータス||Published - 2005 10 1|
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