CO2 concentrations at different heights in a broadleaved/Korean forest (with a mean height of 26 m) were measured with infrared gas analyzer IRGA (model 2250D, LI-COR Inc. and LI-COR, 820) from Aug. to Oct. of 1999, A...CO2 concentrations at different heights in a broadleaved/Korean forest (with a mean height of 26 m) were measured with infrared gas analyzer IRGA (model 2250D, LI-COR Inc. and LI-COR, 820) from Aug. to Oct. of 1999, Apr. to Jul. of 2000, and from Aug. 2002 to Sept. 2003. Based on the collected dada, the diurnal and seasonal dynamics of profiles and storage of carbon dioxide in the forest were analyzed. The diurnal CO2 profiles showed that the vertical distribution of CO2 concentration were different for daytime and nighttime, and the CO2 concentration was highest close to forest floor, no matter at daytime and nighttime. The seasonal profiles of CO2 showed that stratification in the canopy was evident during growth season. CO2 concentrations at different heights (60 m to 2.5 m) had a little change in March, with a difference of 10 mmolmol-1, but had a significant change in July, with a difference of 60 mmolmol-1. In July, there also existed a greater gradient of CO2 concentrations at canopy (22, 26 and 32 m), with a difference of 8 mmolmol-1. The calculated total storage (ΔC/Δt ) of CO2 in the air column with height of 40 m beneath eddy covariance instrument was negative, and made a little contribution to NEE.展开更多
Water transport at the root/soil interface of 1 year old Pinus sylvestris Linn. var. sylvestriformis (Takenouchi) Cheng et C. D. Chu seedlings under CO 2 doubling was studied by measuring soil electric conductanc...Water transport at the root/soil interface of 1 year old Pinus sylvestris Linn. var. sylvestriformis (Takenouchi) Cheng et C. D. Chu seedlings under CO 2 doubling was studied by measuring soil electric conductance to survey soil water profiles and comparing it with root distribution surveyed by soil coring and root harvesting in Changbai Mountain in 1999. The results were: (1) The profiles of soil water content were adjusted by root activity. The water content of the soil layer with abundant roots was higher. (2) When CO 2 concentration was doubled, water transport was more active at the root/soil interface and the roots were distributed into deeper layer. It was shown in this work that the method of measuring electric conductance is an inexpensive, non_destructive and relatively sensitive way for underground water transport process.展开更多
The gas_well system permanently installed in the soil was adopted for studying the dynamic relationship between CO 2 profiles and seedling root growth of Pinus sylvestris var. sylvestriformis (Takenouchi) Che...The gas_well system permanently installed in the soil was adopted for studying the dynamic relationship between CO 2 profiles and seedling root growth of Pinus sylvestris var. sylvestriformis (Takenouchi) Cheng et C. D. Chu. The study was conducted in the Open Research Station of Changbai Mountain Forest Ecological System, The Chinese Academy of Sciences from 1999 to 2001. Four treatments were arranged in the rectangular open_top chambers (OTCs): ambient CO 2+no_seedling, 700 μmol/mol CO 2+no_seedling, ambient CO 2 +seedlings, 700 μmol/mol CO 2+seedlings. By collecting and analyzing soil gas synchronously, it was found that the dynamics of CO 2 profiles were related to the biological activity of seedlings. There were more roots distributed in the top soil and the boundary layer across soil and sand, which made more contributions to the CO 2 profiles due to respiration root. Compared with the ambient CO 2, elevated CO 2 led to the peak of CO 2 concentration distribution shifted from soil surface layer to the boundary layer as seasonally growing of seedling roots. It is suggested the gas_well system is an inexpensive, non_destructive and relatively sensitive method for study of soil CO 2 concentration profiles.展开更多
基金This study is supported by The Development Plan of State Key Fundamental Research of China (973) (contract No. 2002CB412502),by Knowledge Innovation Project of CAS (KZCX1-SW-01-03) and by Natural Science Foundation of China (30170167).
文摘CO2 concentrations at different heights in a broadleaved/Korean forest (with a mean height of 26 m) were measured with infrared gas analyzer IRGA (model 2250D, LI-COR Inc. and LI-COR, 820) from Aug. to Oct. of 1999, Apr. to Jul. of 2000, and from Aug. 2002 to Sept. 2003. Based on the collected dada, the diurnal and seasonal dynamics of profiles and storage of carbon dioxide in the forest were analyzed. The diurnal CO2 profiles showed that the vertical distribution of CO2 concentration were different for daytime and nighttime, and the CO2 concentration was highest close to forest floor, no matter at daytime and nighttime. The seasonal profiles of CO2 showed that stratification in the canopy was evident during growth season. CO2 concentrations at different heights (60 m to 2.5 m) had a little change in March, with a difference of 10 mmolmol-1, but had a significant change in July, with a difference of 60 mmolmol-1. In July, there also existed a greater gradient of CO2 concentrations at canopy (22, 26 and 32 m), with a difference of 8 mmolmol-1. The calculated total storage (ΔC/Δt ) of CO2 in the air column with height of 40 m beneath eddy covariance instrument was negative, and made a little contribution to NEE.
文摘Water transport at the root/soil interface of 1 year old Pinus sylvestris Linn. var. sylvestriformis (Takenouchi) Cheng et C. D. Chu seedlings under CO 2 doubling was studied by measuring soil electric conductance to survey soil water profiles and comparing it with root distribution surveyed by soil coring and root harvesting in Changbai Mountain in 1999. The results were: (1) The profiles of soil water content were adjusted by root activity. The water content of the soil layer with abundant roots was higher. (2) When CO 2 concentration was doubled, water transport was more active at the root/soil interface and the roots were distributed into deeper layer. It was shown in this work that the method of measuring electric conductance is an inexpensive, non_destructive and relatively sensitive way for underground water transport process.
文摘The gas_well system permanently installed in the soil was adopted for studying the dynamic relationship between CO 2 profiles and seedling root growth of Pinus sylvestris var. sylvestriformis (Takenouchi) Cheng et C. D. Chu. The study was conducted in the Open Research Station of Changbai Mountain Forest Ecological System, The Chinese Academy of Sciences from 1999 to 2001. Four treatments were arranged in the rectangular open_top chambers (OTCs): ambient CO 2+no_seedling, 700 μmol/mol CO 2+no_seedling, ambient CO 2 +seedlings, 700 μmol/mol CO 2+seedlings. By collecting and analyzing soil gas synchronously, it was found that the dynamics of CO 2 profiles were related to the biological activity of seedlings. There were more roots distributed in the top soil and the boundary layer across soil and sand, which made more contributions to the CO 2 profiles due to respiration root. Compared with the ambient CO 2, elevated CO 2 led to the peak of CO 2 concentration distribution shifted from soil surface layer to the boundary layer as seasonally growing of seedling roots. It is suggested the gas_well system is an inexpensive, non_destructive and relatively sensitive method for study of soil CO 2 concentration profiles.
