崇明东滩湿地芦苇和互花米草N、P利用策略的生态化学计量学分析

Ecological stoichiometrical analysis on the strategies of utilization of nitrogen and phosphorus in Phragmites australis and Spartina alterniflora in Chongming Dongtan wetland

关键词:  芦苇  互花米草  N、P含量  季节变化  土壤  崇明东滩湿地

Key words:  Phragmites australis  Spartina alterniflora  contents of N and P  seasonal dynamic  habitat soil  Chongming Dongtan wetland

摘要:

测定了崇明东滩湿地典型植物群落内芦苇和互花米草各器官及土壤中的N、P含量和N:P,揭示了它们的季节性动态,并对其N、P利用对策进行了生态化学计量学分析。结果表明:两种植物的N、P含量差异显著且芦苇>互花米草; 不同植物以及同一植物不同器官的N、P含量随生长节律发生明显变化; N、P含量的器官分配模式对于芦苇和互花米草均是叶>茎>根; 两种植物地上部分和地下部分N、P含量5月>9月>7月; 芦苇N、P积累量>互花米草; 2种植物地上部分N、P含量差异显著; 互花米草生境土壤各月份N含量均高于芦苇生境土壤; P含量仅在5月份高于芦苇生境土壤,其它月份均低于芦苇生境土壤。芦苇叶片N含量与生境土壤N含量相关不显著,叶片P含量与土壤P含量显著正相关; 互花米草叶片N含量与土壤N含量极显著正相关,叶片P含量与土壤P含量相关不显著。芦苇和互花米草叶片N:P与土壤N、P含量及N:P间相关均不显著。芦苇在生长初期和生长末期的N:P<14,表明其生长受到N限制; 处于生长旺季时,14<N:P<16,表明其受到N、P共同限制。互花米草在各月份的N:P<14,说明其主要受到N限制。总体而言,N素是芦苇和互花米草净初级生产力的主要而经常性的限制因子。

Abstract:

N and P contents and N:P in different organs of Phragmites australis and Spartina alterniflora and habitat soil in the typical plant community in Chongming Dongtan wetland were measured. Based on the seasonal dynamics and the strategy of N and P utilization of the two species were analyzed using the theory of ecological stoichiometry. The results showed that the contents of N and P in the two species differed significantly,and the order was P.australis>S.alterniflora. The contents of N and P in different species and the different organs of the same species differed in course of plant growth. The allocation of N and P in different organs of P.australis and S.alterniflora was in the order of leaf>stem>root. N and P contents of the above-and below-ground parts of the two species,was in the order of May>September>July. Accumulation of N and P in P.australiswas higher than those in S.alterniflora. The contents of N and P in the above-ground parts of the two species differed significantly. N contents in S.alterniflora habitat soil were more than those of P.australis. Only in May,soil P contents in S.alterniflora habitats were more than that in P.australis,but in July and September,soil P contents in P.australismore than those in S.alterniflora habitats. N contents in leaves of P.australis were not significantly correlated with those in its habitat soil,while P contents in leaves of P.australis were significantly positively correlated with P contents in its habitat soil. The N contents in leaves of S.alterniflora were significantly positively correlated with soil N contents in its habitat soil,while P contents in leaves of S.alterniflora were not significantly correlated with P contents in its habitat soil. The N:P ratio in leaves of and S.alterniflora had no significant correlation with N,P contents and N:P in habitat soil. At the early and last growth stage,N:P<14 for P.australis,suggesting the growth of P.australis at these stages were N-limited,but at the fast growth stage,14<N:P<16 for P.australis,suggesting the growth of P.australis at this stage was N-and P-limited. For S.alterniflora,N:P<14 in May,July and September,suggesting that the growth of S.alterniflora was N-limited. Generaly,the primary productivity of P.australis and S.alterniflora was N-limited at most cases.