Abstract. An experiment was conducted to investigate the effect of seasonally
asymmetric warming on ecosystem respiration (Re), CH4 uptake, and
N2O emissions in alpine grassland of the Tianshan of central
Asia, from October 2016 to September 2019. The annual means of Re, CH4,
and N2O fluxes in growing season were 42.83 mg C m−2 h−1,
−41.57 µg C m−2 h−1, and 4.98 µg N m−2 h−1,
respectively. Furthermore, warming during the non-growing season increased
Re and CH4 uptake by 7.9 % and 10.6 % in the growing season and 10.5 % and
9.2 % in the non-growing season, respectively. However, the increase in
N2O emission in the growing season was mainly caused by the warming
during the growing season (by 29.7 %). The warming throughout the year and
warming during the non-growing season increased N2O emissions by
101.9 % and 192.3 % in the non-growing season, respectively. The Re, CH4
uptake, and N2O emissions were positively correlated with soil
temperature. Our results suggested that Re, CH4 uptake, and N2O
emissions were regulated by soil temperature, rather than soil moisture, in
the case of seasonally asymmetric warming. In addition, the response rate
was defined by the changes in greenhouse gas fluxes driven by warming. In
our field experiment, we observed the stimulatory effect of warming during
the non-growing season on Re and CH4 uptake. In contrast, the response
rates of Re and N2O emissions were gradually attenuated by long-term
annual warming, and the response rate of Re was also weakened by warming over
the growing season. These findings highlight the importance of warming in
the non-growing season in regulating greenhouse gas fluxes, a finding which
is crucial for improving our understanding of C and N cycles under the
scenarios of global warming.
Different responses of ecosystem CO<sub>2</sub> and N<sub>2</sub>O emissions and CH<sub>4</sub> uptake to seasonally asymmetric warming in an alpine grassland of the Tianshan
