The evolution of crop cultivation and paleoenvironment in the Longji Terraces, southern China: Organic geochemical evidence from paleosols

Chronosequencing methanogenic archaea in ancient Longji rice Terraces in China

“…It is recorded that both standard rice price index in China [1] and the number of wars in South China [53] were highest in Stage B during the past 1000 years. Such social turbulences and climate change are expected to be concomitant with weakening farming activity, which is supported by the evidence of decreased exogenous carbon input, characterized by the decrease in the values of the average chain length of odd-carbon-number n-alkanes, ranging from n-C 25 to n-C 33 (ACL 25-33 ) [12]. Consistently, the SOC content gradually decreased in Stage B (Fig.…”

“…The variations in the methanogenic archaeal communities within the four stages can well reflect the centennial-scale variations in local anthropogenic activity. In Stage B, Jiang et al [12] found a general enhancement of farming activity, compared with Stage A. Correspondingly methanogenic archaeal abundances in Stage B were generally higher than those in Stage A (Fig.…”

“…S1). Due to climate deterioration, the alternation of hydroponic and dry farming activity in Stage B occurred [12]. Furthermore, there are indications that several events have occurred in Longsheng village nearby the Terraces in Stage B, because there are two obvious peaks of soil Mn content, around CE 1865 (Layers 19-23) and in CE 1452-1460 (Layers 29-33) (Fig.…”

“…Thus, with long-term rice cultivation, the plough layer of terraces has gradually turned into plow pan, a densified soil layer with low infiltration, making the cultivated horizon a bottom-up chronological sedimentary sequence and their soil physico-chemical properties reflect historical human-environment interactions (Fig. S1) [11,12]. Using radiocarbon dating, and physical and geochemical analyses, in combination with the analyses of n-alkanes and organic carbon stable isotopes (d 13 C org ), these authors investigated four profiles of Longji terraced paddy soils and consistently find the intimate relations between farming activities and environmental changes over the past few hundred years.…”

GIS-based detection of terraced landscape heritage: comparative tests using regional DEMs and UAV data

“…Beyond recognition as a world heritage, there is a growing scientific interest in analyzing different aspects: the historical anthropological and archeological roots has been recognized (Ferro-Vázquez et al 2017); their intrinsic nature in environmental transformation and its implications on land use and soil properties has been investigated (Jiang et al 2017), and interest is growing in the microclimate and geomorphology of the areas affected by the phenomenon. Consequently, the risks deriving from their abandonment are hydrogeological (Sammartano and Spanò 2014) and in weighing the agronomic and ecological balance of the territories with the necessarily social and economic consequences (Londoño et al 2017).…”