新疆北部荒漠典型“风滚”植物角果藜多态繁殖体生产的生态适应意义

Propagule polymorphism is one of the reproductive strategies that has evolved as a long-term adaptation of plants to harsh and variable environments. The species selected as the experimental organism is Ceratocarpus arenarius, one of the predominant species in plant communities of the cold desert region of northern Xinjiang. Ceratocarpus arenarius is a typical “tumbleweed” and an amphi-basicarpic species that produces polymorphic propagules with various degrees of dormancy. The occurrence and development of the polymorphic propagules and their effects on offspring fitness, polymorphic propagules production in heterogeneous habitats and the effects of plant tumbling on dispersal and placement of polymorphic propagules with different degrees of dormancy and the population patterns of this species will be quantified for C. arenarius. Through the above study, we will determine the relationship between different morphologies and sizes of the propagules and the developmental patterns of their flowers and between color and size of embryo and seed germination and seedling establishment. More specifically, the plastic response of polymorphic propagules production of this species to the heterogeneous environmental conditons of its habitat will be ascertained. Moreover, we will forecast the effects of polymorphic propagules and plant tumbling on population patterns of temporal and spatial distribution in the desert region of northern Xinjiang. Thereby, we will explore the ecological adaptive strategies of this tumbling species with polymorphic propagules to its various habitats in the cold desert. The information collected in this study will serve as a basis for the development of a general theoretical basis on maintenence of the desert ecosystem of northern Xinjiang and as an important resource for people working to protect and restore this arid region of northwest China.

繁殖体多态性是植物长期适应严酷环境条件而形成的一种繁殖策略，是植物适应性进化的重要特征之一。本项目将以新疆北部荒漠植物群落中同时兼具“风滚”扩散特性、地上-地表结实以及多态繁殖体等特点的优势藜科植物角果藜为研究材料，通过对该物种多态繁殖体的发生与形态建成及其对子代适合度的影响、生境异质性对多态繁殖体生产及“风滚”扩散特性对不同休眠程度的多态繁殖体扩散和定植及种群格局的影响等研究，分析该物种繁殖体形态差异与其花器官发生及多态繁殖体胚形态与其萌发行为和幼苗建成的关系，揭示该物种多态繁殖体生产对异质生境的可塑性响应特征，预测该物种在新疆北部的种群分布动态，探讨多态繁殖体与其“风滚”扩散特性的耦合对荒漠环境的生态适应对策，以期为全面揭示新疆北部荒漠生态系统的维持和演变提供重要理论依据，并为新疆荒漠区的生态保育与治理提供理论资料。

繁殖体多态性是植物长期适应严酷环境条件而形成的一种繁殖策略，是植物适应性进化的重要特征之一。本项目以新疆北部荒漠植物群落中同时兼具“风滚”扩散特性、地上-地表结实以及多态繁殖体等特点的优势藜科植物角果藜为研究材料，通过对该物种多态繁殖体的形态及其子代适合度、生境异质性对多态繁殖体生产等方面的研究，得出如下主要结果：该物种属于典型的具多态繁殖体的地上-地表结实物种，多态繁殖体在苞片上针状附属物的长度和角度、苞片上毛状附属物的密度、以及胚的形态和颜色上均呈现出明显的变异式样，繁殖体、果实及其胚的质量在不同形态间存在显著差异，且均呈a>c>f的规律。当生长在不同生境类型的土壤条件下，F0代植株扩散单元数量表现为(f > c)> > a。来源于三种扩散单元的F1代植株在大小、生物量及其分配上具有显著差异。与F0代相比，F1代植株表现为：a:(c+f)比值在沙漠土(贫瘠土壤)中呈不变或增加趋势，在草原土(良好土壤)中呈下降趋势；c:(a+f)比值在沙漠土和草原土中均呈增加趋势；f:(a+c)比值在沙漠土和草原土中均呈下降趋势。在盐漠土中，来源于扩散单元a和c的F1代植株与其在沙漠土中的趋势相同，但来源于扩散单元f的F1代植株则与沙漠土和草原土中的趋势相同。当生长在不同土壤水分、养分及密度条件下，地表扩散单元a、植冠的中部(c)和顶部(f)扩散单元形成的植株在总生物量、扩散单元生物量及其分配、不同形态扩散单元的数量及其百分率上均存在显著变化。扩散单元的数量和质量随环境条件胁迫而变化，扩散单元f的变差系数最大，而扩散单元a的最小。因此，土壤理化特性及环境条件的差异可引起角果藜植株大小、生物量及其分配、以及后代产生的各形态繁殖体比例的可塑性变化，这是该物种在不可预测环境条件的一种适应策略。