闽江口芦苇与短叶茳芏空间扩展对湿地土壤磷赋存形态的影响

选择闽江口鳝鱼滩的芦苇湿地、短叶茳芏湿地以及芦苇与短叶茳芏空间扩展形成的交错带湿地为对象,研究了不同湿地土壤磷赋存形态的分布特征及其主要影响因素。结果表明,不同湿地土壤中各形态磷含量整体表现为HCl-Pi > NaOH-Pi > Residual-P > NaHCO₃-Pi > NaOH-Po > Sonic-Pi > Resin-Pi > NaHCO₃-Po。其中,难分解态磷占TP的比例最高（Resin-Pi、NaHCO₃-Pi、NaHCO₃-Po）,为48.3%-51.1%;中等易分解态磷次之（NaOH-Pi、NaOH-Po、Sonic-Pi、Sonic-Po）,为37.4%-38.8%;而易分解态磷最低（HCl-P、Residual-P）,为11.5%-12.9%。交错带湿地土壤中易分解态磷、中等易分解态磷和难分解态磷含量相对于纯群落湿地均发生了明显改变,其值相比芦苇湿地分别提高了10.6%、19.2%和22.6%,相比短叶茳芏湿地分别提高了1.6%、11.5%和16.6%,原因主要与二者空间扩展过程中交错带湿地土壤的理化性质特别是粒度组成、pH以及Fe、Al含量均较纯群落湿地发生明显改变有关。芦苇与短叶茳芏的空间扩展整体改变了湿地土壤的全磷（TP）含量和储量,相对于芦苇湿地和短叶茳芏湿地,交错带湿地土壤的TP含量分别增加了20.0%和7.1%,而磷储量分别增加了12.0%和18.0%。研究发现,芦苇与短叶茳芏的空间扩展不但改变了湿地土壤中磷的赋存状况,而且亦可能改变不同磷形态之间的转化。交错带湿地土壤磷赋存状况有助于缓解芦苇与短叶茳芏空间扩展过程中对磷养分的竞争压力,从而可能在一定程度上维持交错带湿地系统的相对稳定。

Effects of spatial expansion of Phragmites australis and Cyperus malaccensis on distribution and stock of different phosphorus forms in marsh soils of the Min River estuary

To investigate the distributions and stocks of different phosphorus (P) forms in marsh soils in Shanyutan of the Min River estuary, the Phragmites australis marsh (PA), Cyperus malaccensis marsh (CM) and ecotonal marsh (P. australis-C. malaccensis marsh,PA-CM) were studied. The results showed that easily decomposed phosphorus (Resin-Pi, NaHCO₃-Pi and NaHCO₃-Po) in total phosphorus (TP) were 48.3%-51.1%, followed by moderately decomposition phosphorus (NaOH-Pi, NaOH-Po, Sonic-Pi, Sonic-Po) (37.4%-38.8%) and hardly decompose phosphorus (HCl-P and Residual-P) (11.5%-12.9%). The contents of easily decomposed phosphorus, moderately decomposed phosphorus, and hardly decomposed phosphorus forms in soils of PA-CM significantly increased by 10.6%, 19.2% and 22.6% compared with those in soils of PA, while increased by 1.6%, 11.5% and 16.6% compared with those in soils of CM, respectively. The reasons for it should be attributed to the alterations of physical and chemical properties in soils of PA-CM such as grain composition, pH, Fe and Al contents during spatial expansion. The spatial expansion of PA and CM also changed the contents of TP and the stocks of P in soils of PA-CM. Compared with PA and CM, the levels of TP in soils of PA-CM increased by 20.0% and 7.1% and the stocks of P increased by 12.0% and 18.0%, respectively. This paper found that the spatial expansion of PA and CM not only altered the distributions and stocks of phosphorus forms in marsh soil, but also changed the transformation of different phosphorus forms. The distributions and stocks of phosphorus forms in the soils of ecotonal marsh were favorable for alleviating the competitive pressure of phosphorus for P. australis and C. malaccensis during their spatial expansion, which, to some extent, might maintain the stability of the ecotonal marsh ecosystem.