【摘要】 报道了马占相思与大叶相思两种豆科植物叶内养分的动态及养分转移特征 ,分析测定两种植物的绿叶与黄叶内氮、磷、钾、钠、钙、镁等 6种元素的含量。结果表明 ,两种植物的成熟叶养分含量季节性变化不明显 ,全年养分水平较为稳定。马占相思体内氮、磷、钾、镁养分水平显著高于大叶相思 ,这 4种元素在绿叶与黄叶内的含量也有显著差别。两种植物对 4种元素大量转移再利用 ,但对钙、钠没有表现出转移 ,大叶相思与马占相思平均养分转移率分别为 :氮 49.8% ,39.8% ,磷 75 .5 % ,66.5 % ,钾 61 .8% ,43.3% ,镁 1 9.4% ,1 5 .6%。作为豆科植物具有的固氮能力 ,使转移率格局与非豆科植物不同 ,表现为氮转移率降低 ,而其它元素转移率显著上升。马占相思氮转移量高达 1 1 2 .43kg/( hm2 · a) ,磷 1 2 .74kg/( hm2 ·a) ,钾 45 .78kg/( hm2 · a) ,但镁只有 1 .64kg/( hm2 · a) ,大叶相思养分转移量为 :氮 90 .1 7kg/( hm2 · a) ,磷 7.2 3kg/( hm2·a) ,钾 34.49kg/( hm2·a) ,镁 1 .5 8kg/( hm2·a) ,通过转移获得的养分与植物从环境中吸收的养分量大致相当 ,这两个养分源共同满足了植物生长过程中的养分需求。更多还原

【Abstract】 Two legume species (Acacia auriculiformis and Acacia mangium) were widely planted as pioneer species in tropical and subtropical regions of China. They were both adaptive to the infertile habitat. This paper examined the nutrient dynamics and nutrient resorption of the two species. The forests studied were at the age of 12. Mature green leaves and abscising leaves were sampled monthly over a year. Samples were oven dried and determined for N, P, K, Na, Ca, Mg. Meanwhile, litter traps were mounted under the forests and the litter collected and weighed monthly. Nutrient resorption rate was estimated with the nutrient difference between green leaves and abscising leaves. The results showed that the nutrient content of mature leaves of the two species had no seasonal pattern. All nutrient remained relatively stable over the year. The nutrient level of N, P, K, Mg in A.mangium was significantly higher than that in A.auriculaiformis. And four elements in green leaves showed markedly higher than those in abscising leaves, which indicated the obvious nutrient resorption in leaves. The mean nutrient resorption rates of A.auriculaiformis and A.mangiumwere: N 49.8%,39.8%,P 75.5%,66.5%, K 61.8%,43.3%,Mg 19.4%,15.6%, with no certain resorption for Ca and Na. The nitrogen fixing ability of legumes made them different from non-legumes in nutrient resorption pattern, i.e. lower N resorption and higher P, K, Mg resorption. The nutrient quantity resorbed in A.mangium was N 112.43 kg/(hm 2·a),P 12.74 kg/(hm 2·a),K 45.78 kg/(hm 2·a),Mg 1.64 kg/(hm 2·a) respecitively. The nutrient quantity resorbed in A.auriculaiformis was N 90.17 kg/(hm 2·a), P 7.23 kg/(hm 2·a), K 34.49 kg/(hm 2·a), Mg 1.58 kg/ (hm 2·a). The nutrient acquired by resorption was equivalent to that absorbed from the environment by roots. Both nutrient sources of resorption and root absorption meet the demand of plant growth.更多还原