摘要
Arid and semi-arid regions,which account for more than 30%of the Earth’s land area,increasingly dominate the spatiotemporal trends in global carbon fuxes.The Horqin Sandy Land is a typical semi-arid fragile ecosystem in northern China.Understanding the components of the carbon budget in ecosystems under conditions of extreme soil moisture limitations provides a foundation for comprehending the carbon balance in semi-arid ecosystems.The seasonal and diurnal variations in soil respiration(R_(s))in semi-mobile dune(SD)and meadow wetland(MW)ecosystems of the Horqin Sandy Land were examined,and the sources of CO_(2)emissions from Rs were identifed using stable carbon isotopes.The responses of Rs and ecosystem respiration(R_(eco))to environmental temperature,moisture and leaf area index(LAI)were revealed.The results showed that on a seasonal scale,in SD with soil moisture content(M_(s))below feld capacity(FC),M_(s) had a greater infuence on Rs than soil temperature(T_(s))during the growing season.Changes in the LAI during the middle and late growth period afected R_(s) by altering root carbon supply.In MW,the most favorable M_(s) for R_(s) was near FC.The increase in LAI before mowing could efectively promote root and soil microbial respiration,and the decomposition of litter driven by T_(s) was the main form of R_(s) at this time.After mowing,root respiration and soil microbial respiration were the main processes contributing to CO_(2)emissions.On a daily scale,relative humidity(RH)dominated the R_(s) variation under dry conditions,whereas in other conditions,the R_(s) was adequately explained by temperature in SD and MW.The overall R_(eco)was larger than R_(s),but occasionally R_(s) was greater than R_(eco).The efects of temperature,moisture and LAI on R_(eco)and R_(s) varied with growing season.Adding factors,such as ecosystem type,vegetation growth,water,and heat,to the carbon cycle model can improve predictions of carbon emissions,and aid in further management decisions in arid and semi-arid areas.
基金
supported by the National Natural Science Foundation of China(the Yellow River Water Science Research Joint Fund)(U2243234)
the National Natural Science Foundation of China(51939006)
the National Natural Science Foundation of China(52109022,52169002)
the Inner Mongolia Autonomous Region Science and Technology Leading Talent Team(2022LJRC0007)
the Ministry of Education of China Innovative Research Team(Grant IRT_17R60)
the Chinese Ministry of Science and Technology Innovative Research Team in Priority Areas(Grant 2015RA4013)
the Inner Mongolia Agricultural University Basic Research Project(BR22-12-04,BR221012)
the Inner Mongolia Industrial Innovative Research Team(Grant 2012)
frst-class Academic Subjects Special Research Project of the Education Department of Inner Mongolia Autonomous Region(No.YLXKZX-NND-010).
