互花米草凋落物有机碳在不同发育阶段盐沼中的分解动态

Decomposition dynamics of organic carbon in Spartina alterniflora litter in developing salt marshes

采用分解袋法,在江苏盐城新洋港互花米草(Spartina alterniflora)盐沼,根据盐沼发育阶段,从海向陆设置以下5个样地:建群3年互花米草盐沼(SAF2011)、5年互花米草盐沼(SAF2009)、11年互花米草盐沼(SAF2003)、25年互花米草盐沼(SAF1989)以及互花米草-碱蓬(Suaeda salsa)盐沼(SAF-SS),研究互花米草凋落物分解过程中总有机碳、惰性有机碳及活性有机碳动态变化。结果表明:(1)各样地凋落物经过1年的分解,其总有机碳、惰性有机碳、活性有机碳残留率逐月下降,惰性有机碳残留率高于活性有机碳残留率,有机碳各组分分解残留率随盐沼建群时间增加而增加;(2)各样地凋落物有机碳分解速率有明显季节变化,总有机碳、惰性有机碳和活性有机碳分解速率分别在8、1和6月最高,总有机碳和活性有机碳分解速率在10和2月较低,惰性有机碳分解速率在12和2月较低;活性有机碳分解速率高于惰性有机碳;凋落物总有机碳和活性有机碳分解速率均随着互花米草盐沼建群时间的增加而下降,建群3年盐沼中凋落物惰性有机碳分解速率最高;(3)凋落物分解后,总有机碳中惰性有机碳比重增高,活性有机碳比重降低,总有机碳中活性有机碳的分解比例大于惰性有机碳;(4)各样地凋落物总有机碳年分解量分别为0.3167、0.2632、0.2608、0.2380和0.2583 g·g-1,建群3年的盐沼中凋落物有机碳分解量高于其余样地。盐沼发育程度对凋落物的分解动态有显著影响。

In order to characterize the decomposition patterns of total organic carbon （TOC）, re- calcitrant organic carbon （RC） and labile organic carbon （LC） in Spartina alterniflora litter, we buried litterbags at S. alterniflora salt marshes of 3-year-old （SAF2011）, 5-year-old （ SAF2009）, 11-year-old （ SAF2003）, 25-year-old （SAF1989） and S. alterniflora-Suaeda sal- sa salt marsh （SAF-SS） along the Xinyanggang coastal wetland in Yancheng, the largest S. alter- niflora salt marsh in China. The results showed that ： （ 1 ） During the one-year decomposition, the TOC remaining percentage, RC remaining percentage and LC remaining percentage decreased monthly. The RC remaining percentage was higher than the LC remaining percentage, and the re- maining percentages of TOC, RC and LC increased with the developmental duration of salt marsh. （2） The organic carbon decomposition rates differed seasonally. The higher decomposition rates of TOC, RC and LC occurred in August, January and June respectively, whereas the lower de- composition rates of TOC and LC occurred in October and February respectively, and the lower decomposition rates of RC were observed in December and February. The decomposition rate ofLC was higher than that of RC, while the TOC and LC decomposition rates decreased with the de- velopmental duration of salt marsh. The RC decomposition rates were higher in SAF2011 than in the other salt marshes. （3） After litter decomposition, the ratio of RC to TOC increased, while the ratio of LC to TOC decreased. （4） The annual TOC decomposition rates were 0.3167, 0.2632, 0.2608, 0.2583 and 0.2380 g .g-1for SAF1989, SAF2003, SAF2009, SAF2011 and SAF-SS, respectively. These findings suggest that the development duration of salt marsh can affect decomposition processes of organic carbon in litter.