青藏高原高寒草甸两种优势植物的生长及其CNP化学计量特征对模拟增温的响应

以青藏高原高寒草甸和高寒沼泽中的两种优势物种小嵩草(Kobresia pygmaea)和藏嵩草(Kobresia tibetica)为研究对象,采用开顶式增温室(OTCs)模拟气候变暖,对比分析两种植物叶片形态和解剖结构特征、根活性及地上—地下部分化学计量特征对增温的响应差异。结果表明:增温显著增加了小嵩草叶片的长度和叶片的数量,也显著增加了藏嵩草株高和叶片长度;增温没有明显改变小嵩草和藏嵩草的叶片上表皮厚度、下表皮厚度、下表皮细胞角质层厚度、叶肉细胞长和叶肉细胞宽;增温增加了小嵩草根系活跃吸收面积,对小嵩草和藏嵩草其他根系活性指标没有显著影响;增温降低了小嵩草地上部分N含量,对小嵩草地上部分C、P含量没有影响;增温降低了藏嵩草地上部分C、N含量,对P含量没有影响;增温增加了小嵩草和藏嵩草地上部分C/N比,提高了两种优势植物对氮素的长期利用效率;增温对小嵩草地下部分化学计量学特征没有影响,而降低了藏嵩草地下部分C含量和C/N比。

Effects of experimental warming on the growth and stoichiometrical characteristics of two dominant species (Kobresia pygmaea and Kobresia tibetica) in alpine meadow of the Tibetan Plateau

To investigate effects of warming on leaf morphology, anatomical structure, root activities and above-and below-ground parts of Kobresia pygmaea and Kobresia tibetica in alpine meadow and alpine swamp of the Tibetan Plateau in China, a warming experiment was carried out using open-top chambers to simulate climatic warming. The results showed that the warming significantly increased the leaf length and leaf number of the Kobresia pygmaea, and significantly increased the plant height and leaf length in Kobresia tibetica. But there were no significant effects of warming on the thickness of upper cuticle, low cuticle, the cuticular layer of the low cuticle cell, the length and the width of mesophyll cells in the Kobresia pygmaea and Kobresia tibetica. Warming significantly increased the root active absorption area in Kobresia pygmaea. Moreover, warming decreased the N concentrations of aboveground in Kobresia pygmaea, but no effect of warming on C and P concentration was detected, warming decreased the C and N concentrations of aboveground in Kobresia pygmaea, but have no effect of warming on P concentration. Increasing C/N ratio in aboveground with warming indicated that warmer temperature could increase nitrogen use efficiency in both Kobresia pygmaea and Kobresia tibetica. Warming didn''t affect C, N, and P stoichiometry in the belowground part of Kobresia pygmaea, but decreased the C concentration and C/N ratio in below-ground of Kobresia tibetica.