红椎和西南桦营养元素的含量与储量特征

营养元素在植物不同器官及不同营养元素在同一器官中的含量与储量特征,不仅反映植物自身的生物学特性,而且还反映了植物在一定的生境下从土壤中吸收和蓄积矿质养分的能力。为了阐明我国南亚热带不同珍优乡土阔叶造林树种营养元素含量与储量特征,该文通过植物样品采集、实验室测试及统计分析的方法,对位于广西凭祥的中国林业科学研究热带林业实验中心的红椎和西南桦的5种营养元素(N、P、K、Ca和Mg)含量与储量特征进行了研究。结果表明:红椎与西南桦不同器官中营养元素总含量排序均为树叶细根树枝中根粗根干皮根蔸干材,林木各器官营养元素含量均以N和K最高,Ca和Mg其次,P最低;2树种叶片的N、P含量均显著(P0.05)高于其他器官,且叶片N∶P表征2树种均是P制约型植物。除根蔸之外,2树种各器官中营养元素总储量的分配为干材树枝干皮树叶粗根细根中根。红椎的营养元素利用效率略高于西南桦。该研究揭示了红椎和西南桦的营养需求,为调节和改善林木生长环境,以及科学制定林地养分管理策略提供了理论依据。

Characteristics of nutrient contents and storages in Castanopsis hystrix and Betula alnoides

Nutrient elements in different organs of the plant and different contents or storages of nutrient elements in the same organs,not only reflect the plant''s own biological characteristics,but also reflect the plant under certain habitats capacity to absorb and accumulation of mineral from soil. To illustrate the characteristics of nutrient element contents and storages of different valuable local forestation hardwood species in the southern subtropical area of China,we studied the contents and storages of five nutrient elements(N,P,K,Ca and Mg)in Castanopsis hystrix and Betula alnoides from the Experimental Centre of Tropical Forestry of Chinese Academy of Forestry located in Pingxiang,Guangxi. We have got some meaningful results from collecting plant samples,laboratory test and statistical analysis method. The total contents of these five nutrient elements in different organs of Castanopsis hystrix and Betula alnoides were in the order of leaf>fine root>twig>medium root>thick root>bark>root tip>stem. The contents of N and K were the highest among the five elements,followed by Ca and Mg,while P was the lowest in various organs of the two trees. The contents of N and P in leaf were significantly higher than those in other organs for Castanopsis hystrix and Betula alnoides(P<0.05),and the two trees were defined as the P limited plants based on the N:P ratio in the leaf. In addition to root tip,the total storage amounts of nutrient elements in different organs of the two trees in order were stem>twig>bark>leaf>thick root>fine root>medium root. The nutrient utilization efficiency of Castanopsis hystrix was slightly higher than that of Betula alnoides. The study revealed that the nutritional requirements of Castanopsis hystrix and Betula alnoides would provide theoretical basis for adjusting and improving the two trees growing environment,as well as making forest land nutrient management strategies.