矮嵩草草甸主要植物不同器官对氮素的吸收及分配特征研究

以高寒矮嵩草(Kobresia humilis)草甸7个主要植物种为研究对象,利用15 N同位素标记技术,通过分析不同器官对氮素的吸收及分配特征,揭示主要植物种在群落中的生态适应性、竞争力和地位。结果显示:(1)矮嵩草的叶和茎、垂穗披碱草(Elymus nutans)的叶,以及双柱头藨草(Scirpus distigmaticus)和鹅绒委陵菜(Potentilla anserina)的叶、茎、根均偏好累积硝态氮,早熟禾(Poa annua)的穗和叶以及甘肃马先蒿(Pedicularis kansuensis)和短穗兔耳草(Lagotis brachystachya)的根均偏好积累铵态氮。(2)矮嵩草对吸收的甘氨酸和硝态氮主要分配于叶中,铵态氮分配于茎中;双柱头藨草对吸收的甘氨酸和硝态氮主要分配于茎中,铵态氮分配于叶中;垂穗披碱草和早熟禾对吸收的硝态氮和铵态氮主要分配于叶中;垂穗披碱草对吸收的甘氨酸主要分配于根中,而早熟禾将较多的甘氨酸分配到穗中;甘肃马先蒿对吸收的硝态氮主要分配于叶中,铵态氮分配于根中;鹅绒委陵菜对吸收的甘氨酸、硝态氮和铵态氮主要分配于叶中;短穗兔耳草对吸收的甘氨酸主要分配于叶中,硝态氮和铵态氮主要分配于根中。(3)在牧草生长盛期,矮嵩草草甸土壤的有机氮和无机氮主要贡献于甘肃马先蒿的花、早熟禾的穗、垂穗披碱草的根和鹅绒委陵菜的茎叶。研究表明,高寒矮嵩草草甸主要植物不同器官对氮素的吸收及分配呈现多元化特征,因不同植物种的生物学特性和生态适应习性而异。

Nitrogen Absorption and Distribution Characteristics in Different Organs of the Main Plants in Kobresia humilis Meadow

Using ¹⁵N tracer technique, we quantify the characteristics of nitrogen absorption and distribution by organs of seven plant species in the Kobresia humilis alpine meadow, in order to reveal the ecological adaptability, competitiveness and position in the community of the main plants. The results showed: (1) the leaf and stem of K. humilis, the leaf of Elymus nutans, the leaf and stem and root of Scirpus distigmaticus and Pedicularis kansuensis can effectively accumulate nitrate nitrogen. The ear and leaf of Poa annua, the root of P. kansuensis and Lagotis brachystachya Maxim can effectively accumulate ammonium nitrogen. (2) Glycine and nitrate nitrogen absorbed by K. humilis mainly allocated in leaf and ammonium nitrogen allocated in stem. Glycine and nitrate nitrogen absorbed by S. distigmaticus mainly allocated in stem, ammonium nitrogen allocated in leaf. Inorganic nitrogen absorbed by E. nutans and P. annua allocated mainly in leaf. The glycine absorbed by E. nutans mainly allocated in root and by P. annua allocated in ear. Nitrate nitrogen mainly allocated in leaf and ammonium nitrogen allocated in root absorbed by P. kansuensis. The glycine and inorganic nitrogen absorbed by P. anserina mainly allocated in leaf. Glycine absorbed by L. brachystachya mainly allocated in leaf, while nitrate nitrogen and ammonium nitrogen mainly allocated in root. (3) Organic nitrogen and inorganic nitrogen in soil of K. humilis meadow mainly contributed to the flower of P. kansuensis, the ear of P. annua, the root of E.nutans and shoot of P. anserina at herbage growth stage. Absorption and distribution of nitrogen has diversified characteristics in different organs of the main plants in K. humilis meadow, that differed in the biological characteristics and ecological habits of different plant species.