气候变化下准噶尔荒漠一年生植物种子秋萌趋势及对多样性的影响

Seed germination strongly affects plant survival, population size and species distribution. And the seed germination decides the changes of species diversity in the arid area plant communities which were dominated by annual plants,as well as plays an important role in the analysis of biodiversity formation and maintenance mechanisms. However,there is little joint research on seed germination and changes of plant community diversity. This project is based on the typical Junggar Desert in the world as the research area and annual plants which are important for maintaining the stability and diversity of desert ecosystems as the objects of study. In this study,our aim is to summarize the effects of environmental factors such as biological and non-biological effects on the germination of annual plant seeds,as well as the changes on the seed germination and seedling settlement of dominant species such as Haloxylon ammodendron during study the temperature, moisture dependence and systematic evolution of the seed germination of 80 common annual species and the impacts of maternal effects of 12~16 species,climate change and the interaction between inter-species and intra-species on the seed germination in autumn.Furthermore,through intergrating the environmental factors(e.g., soil moisture),functional characteristics(e.g., seed germination) and the change of species diversity to set a theoretical model,and then to summarize the effects of autumn germination of the annual plants on the community diversity under climate change.This project has a great significance for enriching the studies of community ecology, predicting the dynamics of vegetation and characteristics of community succession under climate change in Junggar desert, and proposing the measures of vegetation protection in time.

种子萌发强烈地影响植物生存，种群大小和物种分布范围，而一年生植物占优势的干旱区植物群落，种子萌发状况决定了植物多样性变化，是剖析生物多样性形成和维持机制重要方面，但目前将种子萌发与植物群落多样性变化联合研究极少。本项目以世界典型的准噶尔荒漠为研究地点，以对荒漠生态系统稳定和多样性维持起到重要作用的一年生植物为研究对象，通过研究80个常见物种种子萌发的温度水分依赖、系统进化关系，以及母体效应、气候变化和种间、种内相互作用对种子秋萌的影响，总结生物和非生物作用对种子秋萌的作用强弱，以及这种秋萌变化对白梭梭等群落优势物种种子萌发和幼苗定居的影响。通过建立降水、温度等环境因子、种子萌发等功能特征与植物多样性三者结合的模型，揭示气候变化下一年生植物秋萌对群落多样性的影响。本项目对丰富群落生态学研究内容，预测气候变化下准噶尔荒漠植被动态和群落演替特征，及时提出植被保护措施具有重要意义。

本项目以世界典型的准噶尔荒漠为研究地点，野外调查、实验与理论结合，研究了一年生植物区系组成、分布及资源特征；秋萌物种的多样性特征；种子秋季萌发的生物学、生态学和系统发育原因；具有种子秋天萌发的植物对群落生态功能和植物多样性的影响；理论研究了水生态位基础的植物多样性模型；借鉴一年生植物种子萌发和表型适应理论，研究了豚草（Ambrosia artemisiifolia）和三裂叶豚草（Ambrosia trifida）入侵机理和防控技术。结果表明，新疆荒漠一年生植物（不含栽培种）隶属于20科、109属，共计236种（含8变种），具有重要生态价值的秋天萌发植物（冬季一年生植物）有64种，主要集中在十字花科、禾本科、菊科和紫草科，苋科和豆科则为不易秋天萌发的物种科，秋天萌发特性受系统发育约束。越冬期（12-来年2月）、秋季（9-10月）、春夏季（3-5月）降水可促进物种的秋季萌发。尖喙牻牛儿苗（Erodium oxyrhynchum）的秋天萌发植株竞争能力大于春天萌发植株，着生植株上部种子更容易秋季萌发，母体效应对子代种子秋天萌发没有显著影响。异时萌发是猪毛菜属一年生植物适应干旱降水波动变化的重要对策，异时萌发主要由降水波动和种子寿命短引起的，与果实多态性没有直接关系。准噶尔荒漠起决定性生态功能的物种只有15个左右，其中具备秋天萌发能力物种7个，其重要值占群落总物种重要值（包括乔灌木、草本）的1/3-1/4。以进化稳定群落的水资源利用效率最大为基础，推导出包含水生态位的植物群落物种相互作用模型、种面积模型和种多度模型，丰富和统一了现有的国际植物多样性理论。入侵豚草和三裂叶豚草对茎的高投入是调节密度依赖的种内竞争重要手段，两个物种的分布差异主要由于二者的耐旱能力和种间竞争能力决定，提出的防控技术起到良好的应用效果，实践证明了基础研究对应用研究的指导意义。