中文摘要：

在历史的时期和 C ₃/C₄ 植物的空间、时间的进化期间在象中国黄土高原上的自然植被类型那样的黄土研究有许多争论问题。元素的碳同位素的作文(δ ¹³ C _{在黄土节的 ec} ) 可以为这些问题提供新证据。元素的碳(EC ) 被同位素的作文有的植被，和它的碳的不完全的燃烧生产从正式植被的很小的差别，然后 δ ¹³ C _ec 能被用作一个记录恢复植被的变化。元素的碳被在中央中国黄土高原从 loess-paleosol 顺序使用氧化方法提取，并且它的碳同位素作文被同位素团分光计分析。结果证明在这个区域的植被是 C ₃ 和 C ₄ 植物的一种混合类型，在大部分时间与 C ₃ 植物统治了。后来迟了第四级， C ₃/C₄ 植物不能在中国黄土高原，而是出现变化上跟随一个简单冰川间冰期的周期模式。在 L4 时期逐渐地增加的 C ₃ 植物，和更多的 C ₃ 植物在植物在 L3-L2 时期期间再增加了的 S3 时期，和 C ₄ 期间发生了，在那以后，在 S1-S0 时期期间再统治的 C ₃ 植物。在 paleosol 开发的时期期间， C ₃ 植物充满 S3 和 S1，并且在 S2 和 S0 有更多的 C ₄ 植物。在黄土沉积的时期期间，在 L4 和 L1 有更多的 C ₃ 植物，并且在 L3 和 L2 有更多的 C ₄ 植物。在轨道的时间规模上，植被变化由 δ ¹³ C _ec 记录与花粉数据并且也的结果一致类似于器官的碳获得的结果同位素的作文自从最后冰川的时期。

英文摘要：

There are many controversial issues in loess studies such as natural vegetation types on the Chinese Loess Plateau during the historical periods and the spatial and temporal evolution of C3/C4 plants. Elemental carbon isotopic composition （δ^13Cec） in the loess section may offer new evidence for these problems. Elemental carbon （EC） is produced by incomplete combustion of vegetation, and its carbon isotopic composition has a very small difference from that of the formal vegetation, then δ^13Cec can be used as a record to recover the changes of vegetation. Elemental carbon was extracted by applying the oxidation method from the Ioess-paleosol sequence in the central Chinese Loess Plateau, and its car- bon isotope composition was analyzed by the isotope mass spectrometer. The results showed that the vegetation in this region was a mixed type of C3 and C4 plants, dominated with C3 plants in most of the time. Since late Quaternary, C3/C4 plants may not follow a simple glacial-interglacial cycle mode on the Chinese Loess Plateau, but showing fluctuations. C3 plants increased gradually in L4 period, and more C3 plants occurred during $3 period, and C4 plants increased again during L3-- L2 periods, after that, Cs plants dominated again during S1 --S0 periods. During periods of paleosol development, C3 plants were abundant in S3 and S1, and there were more Ca plants in S2 and SO. During periods of loess sedimen- tation, there were more C3 plants in L4 and L1, and there were more C4 plants in L3 and L2. On the orbital timescale, the vegetation variations revealed by δ^13Cec record are consistent with the results of pollen data and also similar to the results obtained by organic carbon isotopic composition since the last glacial period.