Seasonal metrics and environmental responses to forestry soil surface CO_(2)emission effluxes among three types of lower subtropical forests were consistently monitored over two years with static chamber-gas chromatog...Seasonal metrics and environmental responses to forestry soil surface CO_(2)emission effluxes among three types of lower subtropical forests were consistently monitored over two years with static chamber-gas chromatograph techniques among three types of lower subtropical forests.Results showed that annual CO_(2)effluxes(S+L)reached 3942.20,3422.36 and 2163.02 CO_(2)g·m-2·a-1,respectively in the monsoon evergreen broadleaf forest,mixed broadleaf-coniferous forest and coniferous forest.All the three types of forests revealed the same characteristics of seasonal changes with the CO_(2)effluxes peaking throughout June to August.During this peaking period,the effluxes were 35.9%,38.1%and 40.2%of the total annual effluxes,respectively.The CO_(2)emission process responding to the environmental factors displayed significantly different patterns in forestry soils of the three types of forests.The coniferous forest(CF)was more sensitive to temperature than the other two types.The Q10 values were higher,along with greater seasonal variations of the CO_(2)efflux,indicating that the structurally unique forestry ecosystem has disadvantage against interferences.All the three types of forestry CO_(2)effluxes showed significant correlation with the soil temperature(Ts),soil water content(Ms)and air pressure(Pa).However,stepwise regression analysis indicated no significant correlation between air pressure and the soil CO_(2)efflux.With an empirical model to measure soil temperature and water content in 5 cm beneath the soil surface,the CO_(2)effluxes accounting for 75.7%,77.8%and 86.5%of the efflux variability respectively in soils of BF,MF and PF were calculated.This model can be better used to evaluate the CO2 emission of soils under water stress and arid or semi-arid conditions.展开更多
基金This work was supported by the Na-tional Natural Science Foundation of China(Grant No.30570350)the Knowledge Innovation Program of Chinese Academy of Sciences(Grant Nos.KZCX1-SW-01 and KSCX2-SW-120)+1 种基金the Ministry of Science and Technol-ogy of China(Grant No.2002CB412501)This research was assisted by Mr.Liu Guangren,Drs.Wang Yinghong and Sun Yang from CERN's Atmosphere Center.Thanks are also due to the following people who participated in the field work:Chu Guowei,Wang Xu,Ouyang Xuejun,Xu Guo-liang,Kuang Yuanwen,Luo Yan,Yin Guangcai,Guan Lili,Liu Yan,Meng Ze and Mo Dingsheng.
文摘Seasonal metrics and environmental responses to forestry soil surface CO_(2)emission effluxes among three types of lower subtropical forests were consistently monitored over two years with static chamber-gas chromatograph techniques among three types of lower subtropical forests.Results showed that annual CO_(2)effluxes(S+L)reached 3942.20,3422.36 and 2163.02 CO_(2)g·m-2·a-1,respectively in the monsoon evergreen broadleaf forest,mixed broadleaf-coniferous forest and coniferous forest.All the three types of forests revealed the same characteristics of seasonal changes with the CO_(2)effluxes peaking throughout June to August.During this peaking period,the effluxes were 35.9%,38.1%and 40.2%of the total annual effluxes,respectively.The CO_(2)emission process responding to the environmental factors displayed significantly different patterns in forestry soils of the three types of forests.The coniferous forest(CF)was more sensitive to temperature than the other two types.The Q10 values were higher,along with greater seasonal variations of the CO_(2)efflux,indicating that the structurally unique forestry ecosystem has disadvantage against interferences.All the three types of forestry CO_(2)effluxes showed significant correlation with the soil temperature(Ts),soil water content(Ms)and air pressure(Pa).However,stepwise regression analysis indicated no significant correlation between air pressure and the soil CO_(2)efflux.With an empirical model to measure soil temperature and water content in 5 cm beneath the soil surface,the CO_(2)effluxes accounting for 75.7%,77.8%and 86.5%of the efflux variability respectively in soils of BF,MF and PF were calculated.This model can be better used to evaluate the CO2 emission of soils under water stress and arid or semi-arid conditions.
