作 者 ：郑淑霞, 上官周平
期 刊 ：植物生态学报 2005年 29卷 2期 页码：289-295
Keywords:Carbon isotope composition, C3 plant, Loess Plateau, Climate changes,
摘 要 ：对黄土高原地区4种典型C3植物狼牙刺(Sophora viciifolia)、辽东栎(Quercus liaotungensis)、虎榛子(Ostryopsis davidiana)和酸枣(Zizyphus jujuba var. spinosa)样品稳定性碳同位素组分（δ13C）进行分析，研究了从20世纪30年代至今近70年中不同年代植物δ13C值的变化。结果表明，在近70年中，4种植物δ13C值变化范围为-25.05‰～-29.75‰，平均值为-27.04‰。4种植物叶片δ13C值均呈下降趋势，表明随气候环境变化，近70年4种植物的水分利用效率（WUE）均呈降低趋势。但不同植物叶片δ13C值下降幅度不同：狼牙刺和辽东栎叶片δ13C值下降非常明显，虎榛子叶片δ13C值下降也较明显，而酸枣叶片δ13C值下降不明显。4种植物δ13C值的降低率分别为14.65%、14.46%、11.99%和2.44%，说明不同植物对气候环境因子的敏感性不同，具有不同的适应环境变化的策略，酸枣是4种植物中耐旱能力较强，WUE较高的物种。
Abstract:Increases in the world population combined with accelerated rates of industrialization has led to increases in green-house gases in the atmosphere, particularly CO2 concentrations, resulting in an increase in global temperatures. Water use efficiency (WUE) is a measure of a plant’s performance growing under different environmental conditions, and is an important index that reflects a plant’s ability to adapt to climate change. Carbon isotopes provide a long-term, integrative measure of WUE with high δ13C indicating high WUE. Stable carbon isotopes have become an important technique in ecophysiology studies in recent years for analyzing the long-term WUE of plants growing in different habits and to study the response of plant to different environmental variables, such as light intensity, precipitation, temperature, CO2, and mineral nutrient availability. The Loess Plateau is a critical ecosystem in China but suffers from serious soil erosion problems. Water is the most important limiting environmental factor in this region and research on plant WUE responses to climate change is of particular relevance. However, only a few studies have examined foliar δ13C value in response to climate change in this ecosystem. Four C3 plants that are typical of the Loess Plateau were chosen as materials: Quercus liaotungensis, a tree, and three species of shrubs, Ostryopsis davidiana, Zizyphus jujuba var. spinosa and Sophora viciifolia. Dry leaves were collected from herbarium specimens collected over a 70 year period from the 1930’s to 2002. A total of 25 samples from about 160 plant specimens were analyzed that were collected from the hilly and gully region of the Plateau ranging from the northern Tongchuan to the southern Yanan. The carbon isotope composition (δ13C) of leaves was analyzed using a MAT-251 mass-spectra photometer. The results showed that the variation in the δ13C values differed among the species tested: :Ostryopsis davidiana (-25.05‰ to -29.75‰) > Quercus liaotungensis (-25.51‰ to -29.20‰) > Sophora viciifolia (-25.12‰ to -28.80‰) > Zizyphus jujuba var. spinosa (-26.69‰ to -28.69‰). The mean δ13C value of four plants was -27.04‰ ranging from -25.05‰ to -29.75‰. Comparing the mean δ13C value among four species in the age of 30, 50, 70, 80 and the year 2002 indicated that the following order of Sophora viciifolia (-26.54‰) > Ostryopsis davidiana (-26.99‰) > Quercus liaotungensis (-27.14‰) > Zizyphus jujuba var. spinosa (-27.49‰) is obtained. A decrease in the foliar δ13C value with time was found in all four species, indicating that the WUE of the four species all declined over time. However, the decrease in foliar δ13C values varied among the four species with significant decreases measured in two species, Sophora viciifolia and Quercus liaotungensis, a strong but not significant decrease in the leaves of Ostryopsis davidiana, and only a slight decrease in Zizyphus jujuba var. spinosa. The decrease in the δ13C values in the four species were: 14.65‰, 14.46‰, 11.99‰ and 2.44‰, respectively. It was shown that different species have different sensitivities to climate change, and Zizyphus jujuba var. spinosa was the most drought-tolerant of the four species with a high WUE.