东北岩高兰种群繁殖更新对寒温带亚高山贫瘠生境的响应机制

Empetrum nigrum L.var．japonicum, the evergreen mesophytes and creeping dwarf shrubs, belongs to the second class national key protected endangered plants. It naturally distributes in the northern mountain areas of Daxing’anling and forms single dominant shrub layers. Under the compound effects of the extreme cold climate and sterile soil habitat, the key ecological factors, ecological factor combinations and response processes that affect seed regeneration, seedling growth and clonal propagation of Empetrum nigrum L.var．japonicum may be significantly different. Taking Empetrum nigrum L.var．japonicum as study object, the artificial controlling experiments of temperature and light exposure time, simulated pot experiments with two factors of light intensity and soil nitrogen and the field assisted sample plot investigations will be used to analyze the differences in seed germination process and potted seedling growth of Empetrum nigrum L.var．japonicum. The key factors influencing seed propagation and regeneration of the Empetrum nigrum L.var．japonicum will be revealed. By positioning investigations, the clonal architectures of Empetrum nigrum L.var．japonicum in three different typical habitats (sparse forests, forest margins, stone gap) will be analyzed to clarify the ecological adaptation strategies to different habitats and the basic laws of clonal propagation dispersal. This study will provide theoretical basis and technical measures for reasonable and effective protections and artificial cultivations of Empetrum nigrum L.var．japonicum population, and guide its sustainable management.

东北岩高兰是常绿匍匐状中生矮小灌木，属于国家二级重点保护的濒危植物，自然生长分布于大兴安岭北部山地，形成单优灌木层片。在极端寒冷气候与贫瘠土壤组合生境的复合影响下，影响东北岩高兰的种子更新、幼苗生长与克隆繁殖的关键生态因子或生态因子组合和响应过程可能明显不同。为此，本项目以东北岩高兰为研究对象，采用温度与光照时间人工控制实验、设计模拟光强和土壤氮素双因素幼苗盆栽试验及野外辅助固定样地调查，分析东北岩高兰种子萌发过程和盆栽实生苗生长发育的差异，揭示影响东北岩高兰种子繁殖更新的关键因子，通过定位调查，分析3种典型生境下（疏林下层、林缘和石隙间）东北岩高兰克隆构型等，阐明其对不同生境的生态适应策略及克隆繁殖扩散的基本规律。通过本项研究，预计为东北岩高兰种群的合理有效保护、人工栽培提供理论依据和可借鉴的技术措施，指导东北岩高兰种群的可持续经营。

以大兴安岭北部亚高山贫瘠生境的东北岩高兰为研究对象，以其种群繁殖更新为切入点，旨在揭示影响东北岩高兰种子繁殖更新的关键因子。主要研究内容包括东北岩高兰种子萌发适宜条件及解剖特征，芽和花的结构与特性，分枝及生长特征，生境特点及抗寒的生理机制等。结果表明：①东北岩高兰种皮骨质厚实、种脐相对密闭、种胚较小且萌发后推动力不足，是种子深休眠的主要因素，破坏种皮能够促进种子萌发；用浓硫酸浸种10min、用1000mg/L的GA3浸种12h的种子萌发率最大；正常萌发的幼苗仅维持水分供应可长出多条侧根，并能移栽成活；幼苗喜光，具有较强的耐瘠薄性。②东北岩高兰近枝顶腋枝芽发达；两性花芽的雌性结构多退化开雄花，雌芽未见雄性结构及其退化痕迹；花芽和枝芽均具有早熟性；花芽只着生于当年生枝，晚秋可开花，但大多早春开花芽；枝芽有晚春抽枝现象；抗寒能力极强，能充分利用早春和晚秋有力的自然条件；叶色随气温降低发生变化，增强其抗寒性；东北岩高兰与生存生境协调进化的特性，使其在寒冷贫瘠的生境下，相对高效地合理利用光能、水分、积雪和有限的养分，在寒冷贫瘠的生境下维持种群的延续。③东北岩高兰顶端优势明显，但是具有多变性，形成“一优多强顶端优势”或“多强顶端优势”，以适应多变的极端生境拓展种群生存空间；顶芽萌发对侧枝、特别是非近枝顶侧枝的抽生具有一定的抑制作用；自然条件下匍匐生长的枝逐渐生根，成不同匍匐茎克隆个体，即主要为匍匐茎克隆生长；石隙生境的有性繁殖投入比疏林生境、林缘生境大。该研究初步揭示了东北岩高兰种群适应亚高山贫瘠生境的机理，为保护国家二级濒危植物东北岩高兰提供理论依据。