Human activity and climate change triggered the expansion of rocky desertification in the karst areas of Southwestern China

International audience ; It is conducive to the sustainable development of human beings in karst regions to research the mechanism of karstrocky desertification (KRD) expansion. Whether the large-scale KRD in southwestern China is caused by climate change orhuman activities is still controversial. In this study, the evolution of the KRD in southwestern China over the past 2000 years wasreconstructed through the high-precision δ13C record of stalagmites from Shijiangjun (SJJ) Cave, Guizhou Province, China. Theδ13C of the stalagmites from SJJ Cave exhibited heavy values from the Medieval Warm Period (MWP) to the Little Ice Age(LIA). Furthermore, the δ13C records of other stalagmites and tufa from southwestern China also showed the same significantheavy trend. Because the stalagmite δ13C could record the change of ecological environment, it indicated that the consistentchange of the stalagmites δ13C may record the process of KRD expansion in the karst regions of southwestern China. During theMWP, the stronger Asian summer monsoon and the northward movement of the rain belt led to a dry period in southwesternChina and a wet period in northern China. In contrast, it was wet in southwestern China and dry in northern China during the LIA.In addition, after the Jing-Kang event (JK event, AD1127) occurred at the end of the Northern Song dynasty, the political andeconomic center of China migrated to southern China for the first time, which changed the population distribution pattern oflarger population in the north and smaller population in the south. Therefore, the expansion of KRD in southwestern China wasexacerbated in the MWP due to the change of climate in southwestern China, the migration of a large number of people, wars, thelarge-scale reclamation of arable land, and the cultivation of large areas of crops.