///Zhongba archaeological site is located in the terrace of oft-com:office:smarttags" />Ganjing River, Zhongxian County, Congqing City. To explore the natural background of the salt production and its effect on the environment, samples from a cultural layer with a depth of 12.5 m in Zhongba archaeological site were collected for pollen analysis. According to AMS14 C dating data, these samples were divided into three groups: Late Neolithic period (4 420～3 700 a B.P.), Shang and Zhou Dynasty(3 550～2 700 a B.P.)and Eastern Zhou Dynasty (2 700～2 300 a B.P.). Pollen analysis shows that the herb pollen and fern spores including Poaceae, Elatostema and Athyrium are dominant taxa in all of the samples. Tree and shrub pollen of Pinus, Betula, Pterocarya, Quercus and some subtropical species including Apocynaceae, Ligustrum, Loropetalum and Liquidambar, have relatively low percentage values. Intensive human activities, mainly deforestation and salt production, have been existing in the Zhongba archaeological site and the vicinity since the Late Neolithic. Shrub, grassland and cropland were, therefore, widely distributed. The climate became warmer and moister during Eastern Zhou Dynasty (2 700～2 300 a B.P.), in the meantime the scale of salt production and farming expanded, which resulted in widespread deforestation and promoted grassland development. oft-com:office:office" />
