高寒灌丛草甸生态系统CO_2释放的初步研究

A Primary Study on CO_2 Emission from Alpine Potentilla fruticosa Scrub Meadow Ecosystem

以金露梅(Potentillafruticosa)灌丛草甸生态系统为对象,应用静态密闭箱-气相色谱法对高寒灌丛(GG)、丛内草甸(GC)和裸地(GL)的CO2释放进行了初步研究。结果表明:GG、GC和GLCO2的释放速率均呈明显的单峰型日变化进程,最大释放速率出现在15∶00～17∶00之间,最小值在7∶00前后出现,白天释放速率大于夜晚;CO2释放速率具有明显的季节性变化特征,生长期CO2释放速率明显高于枯黄期,且均表现为正排放,8月为CO2释放高峰期,释放速率GG>GC>GL(P<0.01);2003年6月30日至2004年2月28日,高寒灌丛植被-土壤系统CO2释放量为3088.458±287.02g/m2,丛内草甸植被-土壤系统CO2释放量为2239.685±183.68g/m2,其中基础土壤呼吸CO2的释放量约为1346.748±176.24g/m2,分别占GG和GC释放量的43.61%和60.13%;CO2释放速率的日变化主要受地表和5cm地温制约,而季节动态与5cm地温呈显著正相关关系(P<0.01)。

Using static chamber-GC method, a primary study on CO_2 emission from alpine Potentilla fruticosa scrub (GG), Kobresia meadow (GC) and bare land (GL), interspersing among the scrub, was conducted in alpine P. fruticosa meadow ecosystem at Haibei research station, CAS. The results indicate that CO_2 emission rate from GG、GC and GL showed evident characteristics of daily variations, peaked at 15∶00～17∶00, minimized at 7∶00～9∶00, with higher CO_2 emission rate at daytime than at night. Furthermore, the CO_2 emission also showed a seasonal variation, and the emission rate higher during the plant growing seasons than at the wilting period, and all the emission values are positive. The fastigium of CO_2 emission appeared in August, and the emission rates varied among GG, GC and GL with an order of GG>GC>GL (P<0.01). During the whole experimental period, from 30th June, 2003 to 28th February, 2004, the CO_2 efflux from plant-soil system at GG and GC sites were 3088.458±287.02 g/m^2 and 2239.685±183.68 g/m^2, respectively, while the soil basal respiration was 1346.748±176.24 g/m^2, accounting for 60.13% and 43.61% of the total CO_2 emission from GG and GC, respectively. In addition, the daily variations of CO_2 emission rate were dominated by soil temperature at 5 cm depth and soil surface temperature, and there also existed a significant correlation between the seasonal changes of soil temperature at 5 cm depth and CO_2 emission rate (P<0.01).