若尔盖高原湿地土壤-植物系统有机碳的分布与流动

THE ORGANIC CARBON DISTRIBUTION AND FLOW IN WETLAND SOIL- PLANT SYSTEM IN RUOERGAI PLATEAU

湿地碳素变化对全球气候变化的影响一直是国内外湿地研究的热点。国内对沼泽湿地碳循环的研究主要集中在三江平原,其它地区则鲜见报道。若尔盖高原位于全球气候变化最敏感的区域之———青藏高原的东北部,冷湿的气候条件下沼泽十分发育,泥炭贮量丰富,沼泽面积和泥炭资源贮量均居中国首位。为了评估该区湿地;在全球气候变化中的作用,作者以该区分布最为广泛的 3种沼泽植物群落——木里苔草(Carex muliensis)群落、乌拉苔草(Carex meyeriana)群落和藏嵩草(Kobresia tibetica)群落以及最为典型的3种湿地土壤——泥炭土、泥炭沼泽土和草甸沼泽土为对象,采用田间腐解试验方法,系统研究了高原湿地植物——土壤系统中有机碳的分布与流动,其目的在于:1)探明该区湿地土壤有机碳的数量与分布状况;2)了解植物碳在向土壤流动过程中的消失与残留情况。结果表明,若尔盖高原湿地土壤的有机碳含量一般较高且随土层加深而降低;在植物由活体—立枯—残落物的不同阶段,植物不同化学组分中碳的消失率各异,其中易分解组分碳的消失率最大(3种群落分别为61.37％、69.59％和66.34％),木质素碳的消失率(44.53％～52.98％)略大于纤维素碳的消失率(38.23％～43.86％),3种群落植物碳的总消失率分别为53.8％、60.03％和55.18％;3种群?

The effect of wetland carbon element change on the global climate change has been a focus in the world for a long time. Some works have been done in studying carbon cycles of marsh wetland at Sanjiang Plain in China, but little was reported on the same work in Ruoergai Plateau situated in north-east part of Qinghai-Tibetan Plateau, which is one of the most sensitive areas with respect to global climate change in the world. The cold climate and abundant water in this area, vast marsh area and rich reserves of the peat are all very specific in China and in the world. To evaluate the effect of wetland carbon cycles on global climate change, the author studied organic carbon distribution and flow from three kinds of plant ( Carex muliensis , Carex mey-eriana and Kobresia tibetica) communities to three kinds of soil (peat soil, peat bog soil and meadow bog soil) using a field decomposition approach. The purposes are as follows: 1) .to investigate the amount and distribution of soil organic carbon and 2) to verify the amount of C lost and C retained in the wetlands in Ruoergai Plateau. The results showed that the content of soil organic carbon was high and decreased with the increase of the depth of the soil layer. The disappearing rate of the organic carbon was different in different chemical constituents at different stages of living plants, standing dead and litter. Among several chemical constituents, the disappearing rate of the easy-decomposing C was the highest and reached 61.37% , 69.59% and 66.34% respectively in the three marsh plant communities, while the disappearing rate of the lignin C (44.53% -52.98 % ) was slightly higher than that of the cellulose C (38.23 % - 43.86 % ) . The total disappearing rates of the plant carbon were 53.8 % , 60.03 % and 55.18 % respectively in the three communities. The amount of C retained in soil from litter after 1 and 2 years of decomposition was 30 g·m-2 and 25.5 g·m-2 respectively, while the amount retained in the residual roots was 179 - 223 g·m- and 161-208 g·m-2 respectively. These results indicated that residual plant roots was the main source of soil organic carbon and the amount of organic carbon flow was large because of the higher biomass in wetland ecosystem in Ruoergai Plateau.