【摘要】 植物有机体稳定碳同位素组成受植物生长期间气候环境因子的影响,包含了大量的环境信息。要真正理解植物体同位素组成所包含的环境信息首先要研究植物体同位素组成与环境之间的关系。文章通过分析2002年和2003年青藏高原东部青海省门源县境内隶属于19科41属51种植物叶片的δ13C值,研究高寒草甸植物稳定碳同位素组成的年间变化及其与环境因子的关系,分析影响δ13C值变化的关键因子。结果表明,所测植物的δ13C值分布在一个很小的范围-29.2‰～-24.9‰之间,平均值为-26.9‰,说明所测植物的光合作用均通过C3途径实现,这可能与该研究区较低温度有关。研究发现一年生植物δ13C值明显低于多年生植物,而且一年生和多年生植物δ13C值之间的差异在2002年(t=-3.031,P<0.01)和2003年(t=-3.567,P<0.001)均能达到显著性水平,表明多年生植物水分利用效率显著高于一年生植物,能更好的适应该地区寒冷干燥的低温环境。两年间植物δ13C值有明显不同,2003年显著低于2002年(t=6.786,P<0.001)。通过分析两年间环境因子的变化认为植物叶片δ13C值的年间变化主要是由于降水的变化引起的,随降雨量的增加而降低。不同植物种δ13C值年间变化差别很大,反应了植物对环境变化的不同响应。在植被恢复中应选用植物δ13C值随环境变化存在较大差异的物种,因为此类物种能够采取不同的对策适应该地区环境的变化。更多还原

【Abstract】 The stable isotope compositions of plant organic matters contain an integrated record of environmental conditions during growing season. Interpreting that record requires a full understanding of how the isotope ratios of plant organic matters respond to changes in climate. In this study,by measuring stable carbon isotopes in leaves of 51 alpine plant species belonged to 19 families and 41 genera growing in the east of Tibetan Plateau in 2002 and 2003,we studied the variations of δ13C values between two years and its relationship to environmental factors in order to determine the dominant factors affecting annual changes. The measured δ13C values (ranged from -29.2‰ to -24.9‰ with an average of -26.9‰) indicated that all the considered species perform photosynthesis through the C3 pathway,which reflected the adaptation of alpine plants to extremely low air temperature charactering on the Tibetan Plateau. Leaf δ13C values of annual plants were significantly negative compared with perennial plants both in 2002 (t = -3.031,P < 0.01) and 2003 (t = -3.567,P < 0.001),suggesting that perennials have greater water use efficiency than annuals,i.e. perennials may be more advantageous than annuals in water-limited and low temperature environment on the Qinghai-Tibet Plateau. There was significant difference of δ13C values occurred between two years,with a substantially more positive δ13C values in 2002 than in 2003. By ana-lyzing the variations of climatic factors between two years,the changes of δ13C values could be mainly contributed to the difference of precipitation. However,the variations of δ13C values between two years were species-dependent,although the consistency of the decreasing trend of δ13C values from 2002 to 2003,suggesting distinct responses of different species to environmental changes. It is suggested that plant species showing significant positive δ13C values with same environmental changes should be the optimum choice in vegetation recovery on the Tibetan Plateau because these plants would take different strategies to adapt to variability of environment.更多还原