不同红树植物叶片元素重吸收特征

为明确不同红树植物养分重吸收状况，以福建漳江口拒盐红树秋茄和木榄、泌盐红树白骨壤和桐花树为对象，测定成熟叶和衰老叶中N、P、K、Ca、Mg、Fe、Mn、Cu、Zn含量。结果表明，4种红树植物成熟叶（Zn除外）、衰老叶（Cu除外）养分含量差异显著（P<0.05），衰老叶N、P、K、Cu、Zn含量均低于成熟叶，为正转移，平均转移率分别为65.88%、38.35%、44.27%、35.78%和66.91%；衰老叶Mg、Fe、Mn（木榄除外）含量高于成熟叶，为负转移，平均转移率分别为-120.56%、-45.93%和-30.25%。泌盐红树（白骨壤和桐花树）N和P重吸收效率显著低于拒盐红树（秋茄和木榄）（P<0.05），而泌盐红树的K重吸收效率显著最高（P<0.05）。不同红树植物养分重吸收效率与其成熟叶养分含量呈正相关关系（Mg除外），与其衰老叶均呈负相关关系。综上可知，不同红树植物对不同养分的重吸收具有特异性，秋茄和木榄通过较高的N、P重吸收效率适应滨海的特殊生境，而白骨壤和桐花树则通过提高凋落物的N、P、Mg、Cu、Zn输入，对土壤养分的有效性作出正反馈。

Leaf Nutrient Resorption Characteristics Among Mangrove Tree Species

Nutrient resorption (NR) is a highly-efficient nutrient utilization strategy which develops during the long-term evolution of plants.To clarify the NR characteristics among different mangrove species,plants of salt excluders (Kandelia candel and Bruguiera gymnorrhiza) and salt secreters (Avicennia marina and Aegiceras corniculatum) occurring in Zhangjiang Estuary,Fujian Province,Eastern China were chosen as study objects.The concentrations of N,P,K,Ca,Mg,Fe,Mn,Cu,and Zn in mature and senescent leaves were measured.The results showed that the nutrients in mature (except for Zn) and in senescent leaves (except for Cu) were significantly different among all mangrove species (P<0.05).The N,P,K,Cu and Zn concentrations of senescent leaves were lower than those of mature leaves,with average positive NR efficiencies of 65.88% (N),38.35% (P),44.27% (K),35.78% (Cu) and 66.91% (Zn),respectively.The Mg,Fe,and Mn (except for B.gymnorrhiza) concentrations of senescent leaves were higher than those of mature leaves,with average negative NR efficiencies of -120.56%,-45.93%,and -30.25%,respectively.The N,P,Mg resorption efficiencies in salt-secreting mangroves (A.marina and A.corniculatum) were significantly lower than those in non-salt-secrete mangroves (K.candel and B.gymnorrhiza) (P<0.05),while K resorption efficiencies were significantly higher in salt-secreting mangroves (P<0.05).NR efficiencies among different mangroves were positively correlated with the corresponding nutrient concentrations in mature leaves (except for Mg),and negatively correlated with the corresponding nutrient concentrations in senescent leaves.In conclusion,different mangrove species have different nutrient resorption behaviors.K.candel and B.gymnorrhiza have higher N and P resorption efficiencies to adapt to the nutrient-limited coastal environment,whereas A.marina and A.corniculatum provide a positive input to soil nutrient availability via improving the litter nutrient input (N,P,Mg,Cu and Zn).