典型草原枯落物分解过程中官能团的动态特征

选择锡林浩特东部国家气候观象台的生态监测研究样地,对大针茅(Stipa grandis)、羊草(Leymus chinensis)、糙隐子草(Cleistogenes squarrosa)、知母(Anemarrhena asphodeloides)枯落物的化学结构特征进行阐释。结果表明:(1)枯落物分解速率呈先增大后减小的变化趋势,且知母枯落物分解速率高于大针茅、羊草和糙隐子草;枯落物总碳(TC)含量为富集-释放模式,在第120d时,知母枯落物TC含量高于其他3种植物。(2)大针茅、羊草、知母、糙隐子草枯落物所含的主要官能团为-OH;=C-H、-CH 2、-CH 3;C=O;C=O、C=C;C-O。(3)不同植物枯落物官能团含量在分解初期迅速减少,在分解后期减少趋势较为缓慢,与分解过程中枯落物的分解速率变化趋势一致;知母的含碳官能团含量在分解结束后最低,而羊草的则最大,且知母和糙隐子草损失量最大,与分解过程中枯落物TC含量的特征一致。(4)大针茅的支链化指数最大,羊草的最小;糙隐子草的芳香性指数最大,知母的最小。不同植物芳香性指数在分解初期迅速减少,在分解后期减少趋势较为缓慢,与分解速率变化趋势一致。

Dynamic Characteristics of Functional Groups of Typical Steppe Plants during Withered Litter Decomposition

The chemical structure characteristics of four plant withered litters(Stipa grandis,Leymus chinensis,Cleistogenes squarrosa and Anemarrhena asphodeloides)were studied at the ecological monitoring research plots of the National Climate Observatory in the eastern part of Xilinhot.The results showed that:(1)The decomposition rate of withered litters of the four plants increased first and then decreased that the decomposition rate of withered litters in A.asphodeloides was higher than that of S.grandis,L.chinensis and C.squarrosa.The total carbon(TC)content of withered litters of the four plants followed the enrichment-release mode that the TC content of withered litters in A.asphodeloides was higher than that of other plant withered litters after 120 days.(2)The main functional groups in withered litters of S.grandis,L.chinensis,A.asphodeloides and C.squarrosa were-OH;=C-H,-CH 2,-CH 3;C=O;C=O、C=C and C-O.(3)The content of functional groups of withered litters in different plants decreased rapidly in the initial stage of decomposition,and the decreasing trend was slower in the later stage of decomposition,which was consistent with the change of the decomposition rate of withered litters.At the end of the decomposition,the content of carbon-containing functional groups was the lowest in A.asphodeloides and highest in L.chinensis,respectively.The loss of the content of carbon-containing functional groups in A.asphodeloides and C.squarrosa was the largest,which was consistent with the characteristics of TC content in withered litters during decomposition.(4)The branched-chain index(CH 3/CH 2)of S.grandis was the largest,and that of L.chinensis was the smallest.The aromaticity index of C.squarrosa was the largest,and that of A.asphodeloides was the smallest.The aromaticity index of different plant withered litters decreased rapidly in the initial stage of decomposition,and the decreasing was relatively slow in the later stage of decomposition,which was consistent with the change of decomposition rate.