卷荚相思人工林营养元素的生物地球化学循环特征

采用标准样地法对广西南宁市8年生卷荚相思Acacia cincinnata人工林的N、P、K、Ca和Mg 5种营养元素的含量、积累量、分布与生物地球化学循环进行了研究.结果表明:(1)卷荚相思不同器官营养元素含量以树叶为最高,干材最低,各器官中营养元素含量以N最高,其次是K和Ca,Mg和P最低.(2)卷荚相思人工林营养元素积累量为823.80 kg/hm2,其中乔木层、灌木层、草本层和凋落物层分别占64.86%、20.59%、5.20%和9.35%;(3)卷荚相思人工林营养元素年吸收量、归还量、存留量分别为151.30、84.48和66.82 kg.hm-2.年-1,年归还量占年吸收量的55.84%;(4)卷荚相思人工林营养元素循环系数为0.56,循环速率依次为Mg>Ca>N>K>P.

Biogeochemical Cycling Characteristics of Nutrients in Acacia cincinnata Plantation

Standard plot method was used to study the contents,accumulation,distribution and biogeochemical cycling of five nutrient elements(N,P,K,Ca and Mg) in an 8-year-old Acacia cincinnata plantation in Nanning City of Guangxi.The results showed that nutrient contents in the leaves were the highest among those in different organs of A.cincinnata,with the lowest in the stems.The nutrient contents of N were the highest,followed by Ca and K,and those of Mg and P were the lowest.Total accumulation of these five elements in the plantation was 823.80 kg·hm-2,of which arbor layer,shrub layer,herb layer and litter layer accounted for 64.86%,20.59%,5.20% and 9.35%,respectively.The amount of uptake,retention and return of the five elements in the plantation was 151.30,88.48,and 66.82 kg·hm-2·year-1,respectively.The amount of retention of nutrients accounted for 55.84% of the uptake.The coefficient of the plantation was 0.56,and the cycling speed was: Mg>Ca>N>K>P.