祁连山多年冻土区优势植物生理生化指标对短期增温的响应

Global warming can cause permafrost degradation, thus further lead to changes in structure and function of permafrost ecosystems. Many studies suggested that climate warming and permafrost degradation had effects on plant growth. However, little is known about the effects of climate warming and permafrost degradation on physiological and biochemical characteristics of plants. This project will use open-top chambers as 2-7 years experimental warming treatments on the typical permafrost ecosystems in the Qilian Mountain. The dominant plant species, i.e., Carex atrata L., Kobresia pygmaea (C. B. Clarke), C.moorcroftii Falc. ex Boott，and K. humilis (C．A．Mey．) Serg will be selected. The stoichiometry, crude ash, fiber, protein, amino acid, superoxide dismutase, sugar contents, as well as the antioxidative indices will be analyzed. The principle component analysis, analysis of variance, and multiple regression analysis will be performed to explore the relationship among these physiological and biochemical characterizes and soil temperature and moisture contents, and the response of plant quality to temperature changes will be discussed. The results can improve our understandings of effects of global warming on plant ecology, provide insight into the global change ecology, and also contribute scientific basis for development of husbandry, environmental protection of grassland ecosystems in permafrost regions.

全球变暖会导致多年冻土退化，引起多年冻土生态系统结构和功能的变化。大量研究表明，温度升高和多年冻土退化会改变植物生长，但对植物生理生化特征有何影响还不清楚。本项目以祁连山多年冻土区典型的植被生态系统为研究对象，采用开顶式增温法，对样地进行2到7年的增温，选择对黑穗薹草、高山嵩草、青藏苔草和矮嵩草进行研究，分析其化学计量比，测定粗灰分、纤维素和粗蛋白含量的化学组成成分，研究与抗氧化系统有关的色素含量、氨基酸、超氧化物歧化酶、糖含量等指标，利用主成分分析法、方差分析法和多元回归法，分析这些指标与土壤水分和温度的关系，研究增温过程对不同生态系统类型下优势植物的生理生化特征的影响。研究可明确多年冻土区植物生理指标对增温实验的响应，从而加深全球变化背景下多年冻土区草地生态系统的生理特征变化的理解，促进全球变化生态学的发展，并可为农牧业生产、草地生态系统保护等提供参考。

按照申请书的内容，本项目选择黑河流域的高寒草甸为研究对象，测定不同海拔和生长季植被生理和生化指标。结果表明，叶片中的丙二醛含量随植物的生长发育呈增加趋势，根中的丙二醛含量则在植物发育早期含量较高。叶片和根中的游离脯氨酸含量受物候期的影响。渗透调节物质中可溶性糖、丙二醛和抗氧化系统中的过氧化物酶活性与土壤理化性质多呈正相关关系，与气象因子多呈负相关关系；渗透调节物质中的游离脯氨酸和抗氧化系统中的超氧化物歧化酶、过氧化氢酶活性与气象因子多呈正相关，与土壤理化性质多呈负相关。高山嵩草根部的全磷含量随物候期推移逐渐降低，C:N、N:P、C:P随着物候期的推移均先减小后增大，高山嵩草叶片的C:N和C:P随物候期推移增加，N:P随着物候期的推移先减小后增大。高山嵩草的叶片的有机碳、全氮、全磷含量高于根，大部分优势种的C:N呈现出根高于叶片。项目发表SCI论文2篇（中科院一区论文1篇，二区论文1篇），中文核心12篇，培养硕士生7名。