马占相思中龄林地上部分生物量及养分循环的研究

Above Ground Biomass Production and Nutrient Cycling of Middle age Plantation of Acacia mangium

５年生和６年生马占相思地上部分生物量分别是６５．０和７７．３ｔ／ｈｍ２。５～６年生马占相思地上部分净生产力为１９．９ｔ／ｈｍ２。５年生和６年生时，树木地上部分、林下植物和地表凋落物的Ｎ总积累量分别为５２５．４５ｋｇ／ｈｍ２和５９０．２４ｋｇ／ｈｍ２。Ｐ和Ｋ的积累量在５年生时为２４．５０和２６３．１０ｋｇ／ｈｍ２；在６年生时为２３．８７和３０９．６６ｋｇ／ｈｍ２。在２年３个月的观测期内，年平均凋落物量为４．８７ｔ／ｈｍ２。在５～６年生时，Ｎ、Ｐ、Ｋ、Ｃａ和Ｍｇ的循环速率分别是６０．５％，２３３．０％，４４．６％，６０．７％和４７．５％。研究结果表明Ｐ缺乏是马占相思中龄林生长的主要限制因子。

Above ground biomass production,net primary productivity,nutrient accumulation and distribution in different tree components,litterfall amount and it’s decomposition and nutrient biological cycling of 5 to 6 years old plantation of Acacia mangium are presented in this paper. Biomass of 5 and 6 years old plantations were 65.0 and 77.3 t/hm 2. Net primary productivity of the plantation from 5 to 6 years old was 19.9 t/hm 2. N accumulation by tree component,understorey and litter on forest floor was 525.45 kg/hm 2 at the age of 5 years and 590.24 kg/hm 2 at the age of 6 years. P and K accumulations were 24.50 and 263.10 kg/hm 2 at the age of 5 years,and 23.87 and 309.66 at the age of 6 years. Average litterfall of the plantation in 2 years and 3 months was 4.87 t/hm 2. From 5 to 6 years old,cycling rate of N,P,K,Ca and Mg were 60.5%,233.0%,44.6%,60.7% and 47.5% respectively in the plantation. Results indicate that P deficiency was a main limit for the plantation productivity.