沙地米氏冰草对氮沉降及AM真菌的生态调控响应机制

Against the global environmental background of the annual surge in nitrogen deposition, the in-situ and experimental research is going to be conducted in the response mechanism of A.michnoi to the ecological regulation of simulated nitrogen deposition and AM fungi addition. The research subject A.michnoi is the dominant species unique in Hulunbeier sandy land. The research concentrates on ecophysiological characteristics of A.michnoi, the dynamics in its sexual and vegetative reproduction, the comparison between the production and the nutrient allocation of the population, and its response to ecological regulation and management in the vegetation restoration of sandy land. The research will reveal the ecophysiological response of the A.michnoi population in the process of the module production, and its regulation strategies between the sexual and vegetative reproduction, and its mechanism of reproduction and regeneration, and the nutrient distribution of C, N, P as well as the influence regularity of the ratio threshold within every modular on the plant’s nitrogen utilization and nitrogen absorption efficiency. Besides, the research will construct the quantitative model of A.michnoi's growth and production and the macro-mechanism model of rapid vegetation restoration. The research will deepen the population propagation ecology and its applied theories and methodology will provide the vegetation restoration of Hulunbeier sandy land and the grassland management with scientific instruction.

在全球氮沉降逐年激增环境背景下，以呼伦贝尔沙地特有的优势种米氏冰草为研究对象，开展模拟氮沉降及添加AM真菌的条件下，米氏冰草种群的生态调控响应机制的原位和实验研究。其中包括，米氏冰草的生理生态学特征研究；种群有性繁殖与无性繁殖的动态研究；种群生产与物质分配的比较研究；沙地植被恢复种群生态调控模式及管理决策研究。揭示氮素和AM真菌互作影响下米氏冰草种群构件生产过程相应的生理生态响应、种群有性繁殖与无性繁殖调节策略及种群繁殖更新机制、各构件C、N、P物质分配及其比值的阈值对植物氮素利用率和氮吸收效率的影响规律，构建米氏冰草生产和生长的最佳配置的定量模型与沙地植被快速恢复的机制模型，为种群繁殖生态学理论的深入研究提供依据，其理论和方法也将对呼伦贝尔沙地植被恢复及草地管理等生产实践有科学指导作用。

在全球氮沉降逐年激增环境背景下，本文以呼伦贝尔沙地特有的优势种米氏冰草为研究对象，开展了模拟氮沉降及添加AM真菌对米氏冰草种群的生态调控响应机制的原位和实验研究。结果表明，（1）在花盆控制实验研究中， 高N或低N均能显著提高米氏冰草幼苗的叶绿素含量，低N下米氏冰草的POD和NR均显著升高，而根系活力在低N下显著降低，在高N下显著升高。N素与AM真菌互作下还能继续提高植物叶绿素含量、POD和NR，以及低N下的根系活力；低N下米氏冰草幼苗的菌根侵染率高于高N水平；低N与AM真菌互作能继续提高根系侵染率，而高N与AM真菌互作则降低根系侵染率；低N与AM真菌互作能提高米氏冰草茎叶的P含量、N含量和N/P。（2）在沙地原位研究中，随着N沉降的增加，米氏冰草菌根侵染率及根系活力均呈降低趋势；硝酸还原酶酶活性、过氧化物酶活性和叶绿素含量均在低N浓度（5 g·m-2·a-1和10 g·m-2·a-1）下显著升高，然后逐渐降低。米氏冰草的有性繁殖与无性繁殖之间存在权衡关系，低N能提高生殖比。当N浓度增加到20 g·m-2·a-1时，米氏冰草通过无性繁殖扩大种群数量和空间达到最大值，但过高N浓度（25 g·m-2·a-1）下则降低；N沉降的同时施加适量的P肥则更有利于米氏冰草种群的快速生长和繁殖。氮沉降均能显著提高米氏冰草各构件C、N和P积累量，且随着N浓度的增加，米氏冰草通过调节各构件之间C、N和P养分配置，获得最佳生产量；当N浓度20 g·m-2·a-1时，米氏冰草地上和地下生物量最大，当N浓度15 g·m-2·a-1时，米氏冰草的N和P吸收和利用效率最高，而超过此阈值则降低。本研究为种群繁殖生态学理论的深入研究提供依据，其理论和方法也将对呼伦贝尔沙地植被恢复及草地管理等生产实践有科学指导作用。