广西山口不同演替阶段红树植物叶茎根的生态化学计量特征

Leaves,stems and roots stoichiometry characteristics of mangrove plants at different succession stages in the Shankou National Mangrove Nature Reserve,China

红树林是一种典型的湿地生态系统,研究其生态化学计量特征对了解不同演替阶段红树植物养分利用、分配以及环境适应策略具有重要意义。本文以广西山口红树林保护区由海向岸不同演替阶段的三种红树植物(白骨壤、秋茄和木榄)为研究对象,比较不同器官碳(C)、氮(N)、磷(P)以及沉积物中有机碳(sedimental organic carbon,SOC)、全氮(total nitrogen,TN)、全磷(total phosphorus,TP)的化学计量特征,分析三个演替阶段的红树植物不同器官和沉积物养分的生态化学计量特征。结果表明:C、N、P含量在三个演替阶段植物中均表现为叶、茎大于根(P<0.05),白骨壤叶和茎的N、P含量显著高于秋茄和木榄(P<0.05),不同演替阶段植物对于养分的利用策略不同,演替初期为竞争,演替后期为防御。相关性分析显示,秋茄茎与根中的P含量呈显著负相关(P<0.05),木榄叶与茎中的N含量、P含量均呈显著正相关(P<0.05),红树植物叶、茎的N、P含量与土壤SOC、TP以及C:N有显著的负相关性,随着由海向岸的群落演替,红树植物生长从N限制转为N、P两种元素共同限制。

Mangrove is one of the typical coastal wetland ecosystems.Studying its ecological stoichiometry characteristics is important to understand the nutrient utilization,distribution and environmental adaptation strategies of mangrove plants at different successional stages.In the present study,three typical mangrove species,Avicennia marina,Kandelia obovate,and Bruguiera gymnorrhiza were studied.The stoichiometry characteristics of carbon(C),nitrogen(N),and phosphorus(P)in different organs and the sedimental organic carbon(SOC),total nitrogen(TN),and total phosphorus(TP)in the sediments were measured and compared.The ecological stoichiometry characteristics of different organs and sediment nutrients in three intertidal zones of mangrove plants were also analyzed.The results showed that the C,N,and P contents of the three mangrove plants were higher in the leaves and stems than those in the roots(P<0.05).The N and P contents in the leaves and stems of A.marina were significantly higher than those of K.obovate and B.gymnorrhiza(P<0.05).Mangrove plants have unique adaptation strategies to habitats in the different intertidal zones.At the early stage of succession,the plants were distributed in low tide with a competitive strategy.At the advanced stage of succession,the plants were distributed in high tide and the strategy was changed to defense.Correlation analysis showed that the P content in the stems and roots of K.obovate was negatively correlated(P<0.05),while the N and P contents in the leaves and stems were positively correlated(P<0.05).The contents of N and P in the leaves and stems were negatively correlated with SOC,TP and C:N.It was also found that with the succession of mangrove communities from the sea towards the land,the limiting element for the mangrove plants growth has changed from N to both N and P.