桉树不同成熟度叶片营养元素内循环特征

Circulation of nutrient elements in Eucalyptus leaves of different maturity

揭示桉树人工林不同成熟度的叶片器官所需营养元素变化以及土壤肥力对其影响,对于桉树营林和科学施肥具有重要的生产指导意义。选取广西隆安县小林镇和田东县思林镇的桉树2代萌芽林作为研究对象,测定两个人工林嫩叶、成熟叶、黄叶的C、N、P、K、B、Ca、Mg以及土壤C、N、P、K、Ca、Mg元素含量,并进行相关分析。结果表明,植物叶片的N、P、K、Mg营养元素转移规律是黄叶向成熟叶和嫩叶转移,但C、Ca、B营养元素则是随着叶片的生长发育逐渐积累,黄叶中含量最高,说明施肥时应关注Ca、B元素的持续和有效供给。两片人工林都表现出类似的规律,说明土壤肥力的差异不影响桉树人工林叶片营养元素的内循环规律。桉树嫩叶营养元素含量及其生态化学计量比学特征具有与成熟叶和黄叶不同的表征,在营养物质研究中应予以足够重视。

In this study,we determined the nutrient levels required by leaves at different stages of maturity in Eucalyptus plantations and their relationships with soil fertility,which has important production significance for these forests.We evaluated two generations of Eucalyptus sprouting forests in Xiaolin and Silin Towns in Long’an and Tiandong Counties,respectively,in Guangxi Zhuang Autonomous Region.The content of C,N,P,K,B,Ca,and Mg from juvenile,mature,and senescent leaves and the content of C,N,P,K,Ca,and Mg in the soil were measured.A correlation analysis of the results showed that senescent leaves transferred N,P,K,and Mg to juvenile and mature leaves,while C,Ca,and B gradually accumulated with the growth and development of leaves,with the highest content in senescent leaves.More attention should be paid to the continuous and effective supply of Ca and B.For both plantations,differences in soil fertility had no effect on the circulation of basic nutrient elements in Eucalyptus leaves.The nutrient content and ecological stoichiometry in juvenile leaves of Eucalyptus were different from those in mature and senescent leaves.Future studies should pay attention to this age-related nutritional differences.