Affiliations: Institute of Geographical Sciences and Natural
Resources Research, Chinese Academy of Sciences, Beijing 100101, China | Department of Geography, Mainz University, 55099
Mainz, Germany | Graduate School of the Chinese Academy of Sciences,
Beijing 100039, China
Abstract: Using the static opaque chamber method, the soil respiration rates
(SR) were measured through the continuous experiments in situ in semiarid Stipa
grandis steppe in Xilin River Basin of Inner Mongolia, China from June 2001 to
June 2003, in parallel, the difference between the SR and the ecosystem
respiration rates (TER) were compared. The results indicated that the seasonal
variations of the SR and TER were obvious with higher emissions in growing
season and a relatively low efflux level in non-growing season, furthermore,
the negative effluxes were found in the observation site in winter; the annual
CO_2 efflux of total ecosystem ranged from 160.5
gC/(m^2·a) to 162.8
gC/(m^2·a) and that of soil ranged from 118.7
gC(m^2·a) to 152.3
gC/(m^2·a). The annual SR accounted for about 74.0%
to 93.5% of the annual TER but the results of Analysis of Variance (ANOVA)
indicated that the difference between the annual average TER and SR did not
reach the significance level of 0.05. The TER was under similar environmental
controls as SR, in growing seasons of drought years, the variations of soil
moisture at 0–10 cm and 10–20 cm depth could account for
79.1%–95.6% of the changes of the SR and TER, but in non-growing season,
more than 75% of the variations of the SR and TER could be explained by the
changes of the ground temperature of soil surface layers.
