黑木相思人工林营养元素生物循环特征

对广西南宁市8年生人工林黑木相思9种营养元素(N、P、K、Ca、Mg、Fe、Mn、Zn和Cu)的质量分数、积累量、年净积累量和生物循环进行了研究。结果表明:黑木相思不同器官营养元素质量分数存在明显差异,以树叶为最高,其次是树皮、树枝和树根,树干最低;各器官中大量营养元素质量分数表现为N>Ca和K>Mg>P,微量元素Mn和Fe的质量分数较高,Cu最低。黑木相思人工林养分储存量为987.17 kg/hm2,其中乔木层(749.23 kg/hm2)占75.89%,林下植被层(170.86 kg/hm2)占17.31%,凋落物层(67.06 kg/hm2)占6.79%。黑木相思人工林营养元素年吸收量、归还量、存留量分别为199.05、105.41和93.64 kg/(hm2.a),年归还量占年吸收量的52.96%;循环系数为0.53,不同营养元素的周转期表现为P>K>Fe>N>Ca>Cu>Mg>Zn>Mn。

Biological Cycling of Nutrients in Acaciam elanoxylon Plantation

An experiment was conducted to study the content,accumulation,annual net accumulation and biological cycling of 9 nutrient elements(N,P,K,Ca,Mg,Fe,M,Zn and Cu) in 8-year-old Acaciam elanoxylon in Nanning,Guangxi.Results showed that the contents of the nine nutrient elements in the leaves of A.elanoxylon were highest,followed by bark,branch,root and stem.The N content was highest,contents of K and Ca ranked second,and contents of Mg and P were lowest in macro elements;while contents of Mn and Fe were highest,Zn ranked second,and Cu was lowest in microelements.The total nutrient storage in the plantation was 987.17 kg·hm-2.The nutrient storages were 749.23,170.86,and 67.06 kg·hm-2 for the arbor layer,understory vegetation layer,and litter layer,accounting for 75.89%,17.31%,and 6.79% respectively.The amounts of uptake,retention and return of the nine nutrient elements in the plantation were 199.05,105.41,and 93.64 kg·hm-2·a-1 respectively.The amount of nutrient retention was 52.96% of the amount of uptake.The recurrence coefficient for the plantation was 0.53.The recycling period of P was longest,followed by K,Fe,N,Ca,Cu,Mg,Zn and Mn.