气温和降水变化对科尔沁沙地小叶锦鸡儿生殖物候的调控机制

Reproductive phenology is sensitive to environmental change and have been proposed as indicators for measuring climate change. It is of vital significance to study the effect of climate change on plant. Horqin Sandy Land is sensitive to climate change where is one of the typical fragile ecosystem areas in China. The reproductive phenological changes of the plant mentioned above are directly related to the survival of vegetation themselves and the maintenance of biodiversity. Therefore, it is particularly important to have the research on the mechanism of desert vegetation reproductive phenology to climate change. This research will be carried out in Horqin Sandy Land of Inner Mongolia for its dominant species Caragana microphylla Lam. Artificial methods of infrared radiator and fixed canopy that supplying in the field are used to simulate climate change in this research. The reproductive phenology changes such as flowering, fruiting and seed dispersal of C. microphylla will be studied under different treatments of climate change. Changing pattern of land surface temperature, soil temperature, moisture, organic matter and nutrients content are inspected to analyze the effect of environmental factors on the reproductive phenology of C. microphylla, meanwhile photosynthetic characteristics, hydraulic metabolic and activities of protective enzyme are studied to analyze physiological response processes and adaptation mechanism of plants in the process of climate change. The final purpose of this research is to provide the useful theory basis for degraded vegetation restoration and the maintenance of biodiversity in semi-arid land under climate changing.

生殖物候作为气候变化的指示因子，能够及时反映陆地生态系统对气候变化的响应，在研究气候变化对植物的影响中具有重要意义。科尔沁沙地是我国典型的生态脆弱区和气候变化敏感区，其生殖物候变化关系到植物的生存繁衍和群落的生物多样性，因此，研究科尔沁沙地植物生殖物候对气候变化的响应机制尤为重要。本研究拟以科尔沁沙地优势灌木小叶锦鸡儿为对象，分别利用红外加热器和固定式遮雨棚模拟增温和减雨，通过对其开花、结实、种子扩散等生殖现象的连续观测，分析增温、减雨及其交互作用下生殖物候的变化规律；通过对气温和降水变化后地表温度、土壤温度、湿度、有机质及养分含量等生境条件的连续监测，探讨气候变化影响其生殖物候的环境调控机制；通过对各物候期光合作用、水分代谢和保护酶活性等对气温和降水变化响应规律的分析，确定其生殖物候适应气候变化的生理调控机制；为应对气候变化、加强半干旱沙地退化植被的恢复和物种多样性的维持提供理论依据。

生殖物候能够及时反映陆地生态系统对气候变化的响应，在研究气候变化对植物的影响中具有重要意义。科尔沁地区是我国北方农牧交错带沙漠化最为严重的地区之一，小叶锦鸡儿为该区分布最广的灌木，能有效的固结土壤，提高土壤肥力，改善土壤环境，在从沙丘到沙化草地的植被演替中具有关键的作用，为了解决温度和降水等环境因子变化如何改变小叶锦鸡儿的物候模式和繁殖方式，我们申请了本项目。项目主要研究了温度和降水等环境因子变化条件下小叶锦鸡儿的物候和生殖特征及其影响因素。研究表明：1）增温使小叶锦鸡儿的始花期和末花期明显提前，对花期持续时间和生殖成功率没有显著影响，但却使花朵密度显著降低，从而导致小叶锦鸡儿种子产量显著降低。2）降雨变化对小叶锦鸡儿物候的影响存在年际差异。2015年，降雨变化对小叶锦鸡儿的始花期、末花期和花期持续时间没有显著影响。2016年，增雨使小叶锦鸡儿始花期明显提前，而对末花期没有显著影响，使花期持续时间延长，而干旱使小叶锦鸡儿始花期明显延迟，末花期提前，导致花期持续时间缩短。降雨变化对小叶锦鸡儿坐果率、单荚种子数和种子单粒重均没有显著影响。3）小叶锦鸡儿为虫媒植物，传粉昆虫是其生殖成功的关键。植被盖度、物种丰富度和季节上连续的开花植物有助于当地传粉昆虫的恢复，对访花昆虫多样性和访花频率存在显著的正效应。访花昆虫的恢复使固定沙丘上小叶锦鸡儿生殖成功率显著增加，但植被盖度和物种丰富度的变化对小叶锦鸡儿开花物候没有显著影响。项目实施以来，共发表带有项目标注的论文8篇（包括接收且网络版已刊出1篇），其中SCI收入6篇，国内核心期刊收录1篇，其他英文文章1篇。培养博士后1名，并获得中国博士后科学基金面上项目、特别资助项目各1项。