望天树人工林营养元素含量、积累与分配特征研究

Concentration, accumulation and distribution characteristics of nutrient elements in Parashorea chinensis plantation

对桂西南地区32年生望天树人工林乔木层的N、P、K、Ca、Mg等5种营养元素含量、积累及分配特征进行了研究。结果表明:望天树不同组分中各营养元素含量大致为树叶>树皮>树枝>树根>树干;树叶中以N含量最高,其他各器官中元素含量均以Ca含量最高,其次是N、P、Mg含量,K含量最小。乔木层5种营养元素累积总量达2 451.65 kg/hm2,各元素积累量表现为Ca>N>Mg>P>K,乔木层不同组分营养元素积累量表现为树干>树皮>树叶>枝枝>树根;5种营养元素年净累积量达76.61 kg/hm2。乔木层每积累1 t干物质需要5种营养元素总量为7.12 kg,其中对Ca的需求量最大,其次是N、Mg,对P、K的需求最小。林下灌木层、草本层及凋落物层N、P、K元素平均含量稍高于乔木层,3种元素总积累量分别为7.69、13.58、64.89 kg/hm2。

The concentration, accumulation and distribution of five nutrient elements, including N, P, K, Ca, Mg, were studied in 32 years old Parashorea chinensis plantation stand in southwest of Guangxi. The results showed that the concentration of these five nutrient elements in different components of P. chinensis was roughly in the order of leaf 〉 bark〉 branch 〉 root 〉 stem. The content of N was the highest in leaf, while the content of Ca was the highest in other components, followed by N, P and Mg, the content of K was the lowest. The total accumulations of five nutrient elements in P. chinensis was 2 451.65 kg/hm2, showed as Ca 〉 N 〉 Mg 〉 P 〉 K. The annual net accumulation of these five nutrient elements was 76.61 kg/hm2. The net production of organic matter per ton needed 7.12 kg of these five elements in tree layer, the Ca elements amount was the biggest, followed by the N, Mg and P, and the K was the smallest. The order of accumulation of nutrient elements in P. chinensis was stem 〉 bark 〉 leaf 〉 branch 〉 root. The average contents of N, P, K elements in shrub layer, herb layer and litter layer were slightly larger than those in tree layer, and the accumulation of three nutrient elements were 7.69, 13.58, 64.89 kg/hm2, respectively.