TROPICAL GEOGRAPHY ›› 2018, Vol. 38 ›› Issue (4): 575-585.doi: 10.13284/j.cnki.rddl.003064

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Climate and Human Disturbance Changes since the Late Tang Dynasty in the Karst Area of Liuzhou,Guangxi

ZHAO Zengyou1,SHI Shengqiang2,YIN Jianjun3,ZHANG Chunsheng1,DAI Wen1,QIN Qu1   

  1. (1.Resource and Environment Science Department,Liupanshui Normal University,Liupanshui,Guizhou 553004,China;2.School of Geography Science,Southwest University,Chongqing 400715,China;3.Institute of Karst Geology,Chinese Academy of Geological Sciences// Karst Dynamics Laboratory,Ministry of Land and Resources,Guilin 541004,China)
  • Online:2018-07-05 Published:2018-07-05

Abstract: Medieval Warm Period and Little Ice Age are important climatic events in the last two millenniums. To clarify the characteristics of dry and wet changes in low latitudes and its influence on the development of ancient agriculture and population growth is of great significance. A 60cm continuous cave-sedimental core from Liuzhou, Guangxi province, Southwest China, based on palynological investigation, has revealed that since the 875a A.D., climate and human activities of the research area has undergone six stages:875a A.D.- 940a A.D., the pollen and C/P index both indicated drought event,meanwhile the rice cultivation gradually dropped. The population of the research region was poorly recorded after Late Tang Dynasty. 940a A.D.-1050a A.D., with the climate gradually transferring to humid,the rice cultivation generally developed, and so did the population. 1050a A.D.-1140a A.D., the C/P index pollen record and the stalagmite δ18O all referred this stage as a relatively dry climate, while the rice cultivation and population was similar with prior stage. 1140a A.D.-1370a A.D., Medieval Warm Period, the C/P and Cyperaceae pollen percentage was high, and the high rice pollen and low arboreal pollen also revealed strengthened human disturbance. The historical record indicated that the population of the research area grew quickly in this period. 1370a A.D.-1900a A.D.,Little Ice Age, the climate was drying and cooling, indicated by pollen analysis, which affected the rice cultivation, and the population reduced continuously. 1900a A.D.-2009a A.D. the climate recovered and the rice cultivation area expanded. The result also shows that the climate extremes have a strong corresponds with rice-cultivating and population:during Medieval Warm Period, climate was warm and humid which contributed to the growth of rice-cultivating and population, while in LIA, cold and dry climate decreased the population and the area of rice cultivation. When the Cyperaceae pollen is not local deposit, Cyperaceae pollen percentage and C/P, which are sensitive to moisture, can be used to indicate dry and wet climate changes.

Key words: pollen, charcoal, human activity, dry-humid fluctuation, Medieval Warm Period, Little Ice Age, Liuzhou Guangxi