Modern Pollen Assemblages of Artificial, Disturbed, and Natural Vegetation in China and Their Significance for Reconstructing the Intensity of Agricultural Activity

Abstract

Knowledge of the modern pollen assemblage characteristics of artificial and disturbed vegetation can help reconstruct changes in the intensity of human activity and land use/land cover (LULC) from Holocene stratigraphic pollen records. We obtained pollen assemblage data from 217 agricultural (cultivated cereals) sites, 79 wasteland sites, and 389 natural vegetation sites in different regions. The results show that the pollen of cereals Poaceae and the associated agricultural weeds in artificial and disturbed vegetation contexts are effective indicators of the intensity of human activity, and that the pollen assemblages of natural vegetation accurately reflect the regional zonal vegetation composition. Although the cereals Poaceae content varied greatly among the agricultural sites in different regions, due to factors like cultivation practices, crop types, and terrain, all of them were significant indicators of agricultural activity; additionally, the pollen assemblages of wasteland sites and sites with natural vegetation in different regions were different, and the indicator taxa had an obvious significance as an indicator of the zonal vegetation. There was no consistent linear relationship between cereals Poaceae content and the area of agricultural land. The cereals Poaceae content did not vary with increasing agricultural area in regions with high or lower levels of agricultural production; only in Northeast and North China did it increase with increasing agricultural area, where the agricultural area was below 60%. These results provide a modern process basis for the use of stratigraphic pollen data to reconstruct past changes in agricultural activity and LULC.

Keywords: Artificial and disturbed vegetation, Pollen assemblages, Indicator pollen taxa, cereals Poaceae, Agricultural area