中国滨海盐沼互花米草和芦苇叶片功能性状的纬度梯度变异

Latitude Gradient Variations of Leaf Functional Traits of Spartinaalternifloraand Phragmites australis along the Coastal Saltmarshes of China

叶片功能性状能够反映植物适应环境的策略,可以将环境、个体与生态系统的结构和功能紧密联系起来.目前在空间尺度上探讨叶片功能性状响应环境变化的研究大多集中于森林和草地生态系统,而在滨海盐沼中相对较少.为阐明中国滨海盐沼典型植物互花米草(Spartina alterniflora)和芦苇(Phragmites australis)叶片功能性状的纬度变异格局,我们研究了6种叶片功能性状(叶面积、比叶面积、干物质含量、叶碳、叶氮和叶磷含量)的纬度变异规律.结果表明,互花米草和芦苇分别有3种(叶面积、比叶面积和叶磷含量)和5种叶片功能性状(叶面积、比叶面积、干物质含量、叶氮和叶磷含量)功能性状呈现显著的纬度变异规律,其中只有叶面积的纬度变异规律相似,均随纬度增加先增加后降低.同时两者叶面积与盐度显著负相关,但互花米草更低的斜率表明其具有更强的耐盐能力;土壤无机氮与互花米草叶面积显著正相关,与比叶面积显著负相关,而与芦苇叶面积不显著相关,可见互花米草具有更强的养分吸收能力.此外,互花米草叶片功能性状间的关联性高于芦苇,这可能有利于资源的获取和有效利用.由此可见,耐盐、更强的养分吸收能力以及功能性状间的高关联性可能是驱动互花米草在中国海岸带成功入侵的重要因素.

Leaf functional traits can reflect plant’s strategies of adapting environment.They can also interrelate the environments,individuals and the structures and functions of ecosystem closely.Nowadays,most researches at large-scales about the responses of leaf functional traits to environmental changes mainly focus on forests and grasslands,but relatively less in coastal saltmarshes.Therefore,for illuminating the geographic variations of leaf functional traits in invasive Spartina alterniflora and native Phragmites australis along the coastal saltmarshes of China,we studied the latitudinal variation patterns of six leaf functional traits(leaf area,specific leaf area,dry matter content and the content of carbon,nitrogen and phosphorus).The results showed that three leaf functional traits(leaf area,specific leaf area and the content of phosphorus)of S.alterniflora and five(leaf area,specific leaf area,dry matter content and the content of nitrogen and phosphorus)of P.australis have significant latitudinal variation patterns.Both two species had similar latitudinal variation patterns of leaf area,which increased firstly and then decreased with the increase of latitude.Meanwhile,we found that leaf functional traits of two plants were significantly negative with salinity,but the lower slope of S.alternifloraindicated that the invasive species had a higher salt tolerance.And the soil inorganic nitrogen was positively correlated with leaf area and negatively correlated with specific leaf area of S.alterniflora,but there were no significant relationships in P.australis.The results indicated that the S.alterniflora had stronger abilities of nutrient uptake.In addition,the relevance between leaf functional traits in S.alterniflora was higher than that in P.australis,which may be beneficial to the resource acquisition and utilization by S.alterniflora.Thus,salt tolerance,stronger ability of nutrient uptake,and higher relevance between functional traits could be the important factors that make S.alterniflora invade successfully.