COMPARISON OF CARBON TRANSFER BETWEEN FOREST SOILS IN KARST AND CLASOLITE AREAS AND THE KARST CARBON SINK EFFECT IN MAOCUN VILLAGE OF GUILIN
Guilin Maocun karst underground river catchment is located in Maocun Village,30km to the southeast of Guilin City,covering an area of 10km2. In order to carry out comparative study of soil carbon transfer in karst area and clasolite area,the soil profiles of brown limestone soil in typical karst area(25°11 ′38″N, 110°31′35″E) and red soil in clasolite area (25 ° 11 ′35″N, 110°32′08′E) were selected. Both sites cover forest communities and the distance between them is about 150Om. The rate of C O2 emission from soil respiration in situ,isotope kinetic variation ,and temporal and spatial distribution of CO2 concentration in different soil layers,were monitored and collected. The soil carbon transfer features in karst dynamic system and carbon sink mechanism were analyzed. The results showed that: (1)The rate of CO2 emission of soil respiration from limestone soil is apparently lower than that in red soil. The soil respiration rate in karst area varied from 23. 12 ～271.26mgC/m2 · h,with an average of 111.57mgC/m2·h. The soil respiration rate in the clasolite area varied from 51.60 ～ 326. 28mgC/m2 · h ,with an average of 148. 99mgC/m2 · h. Taking the averages into account,the CO2 emission from limestone soil respiration was 25.12％ less than that in the red soil; (2)The δ13C value of CO2 emission from soil respiration in karst area and in clasolite area was -29. 35‰ ～ -18.26‰ and -29.21‰ ～ -22. 60‰, respectively, with their respective mean values being -22. 68‰ and -26. 21‰. The δ13C value of CO2 emission from soil respiration in the karst area is heavier with greater variations than that in the clasolite area;(3) The CO2 concentration in limestone soil profile had a bi-directional gradient, which could be more obvious in seasons with good hydro-thermal conditions. By contrast, the CO2 concentration in red soil profile had a uni-directional gradient,that is to say ,the deeper the red soil layer, the higher the CO2 concentration. Taking into account the mean values of CO2 concentration in soil profiles,the CO2 concentration in limestone soil ranged between 0. 05％ ～ 0. 60％,with an annual average of 0. 25％ ,the CO2 concentration in red soil ranged between 0. 05％ ～ 1.09％,with an annual average of 0. 57％ ,which indicated that the soil CO, in the lower part of profile could be consumed and absorbed in the carbonate rock dissolution at the soil/rock interface in karst area. In other words, karst processes in soil was one of the carbon sinks.
karst areaclasolite areasoil respirationδ13C valuesoil CO2 concentration
NETL
NSTL
万方数据
维普
