A Study Of Modern Pollen/Vegetation/Land-use Relationships In The Taihang Mountains, Hebei Province, North China

Studies of the modern relationship between pollen, vegetation and land use are essentialto infer past human impact from pollen records. Nevertheless, investigations onanthropogenic indicators in pollen records and modern pollen-vegetation/land-userelationships in small catchment areas are relatively few in China. We present here a study ofpollen assemblages from surface sediment samples in small ponds along several transectsfrom the mountain down to the plain area following the Tuoliang and Qipanshan rivercatchments in the Taihang Mountains, northern China. Pollen taxa from natural vegetationtypes, such as Artemisia, Chenopodiaceae, Pinus and Selaginella sinensis dominate the pollenassemblages in the two catchments, while pollen taxa from crops, such as cereals, Cruciferae,Leguminosae, Solanaceae, Umbelliferae and Cucurbitaceae are co-dominant but relativelycommon. These general trends roughly agree with the actual vegetation composition in thetwo river catchments. However, pollen percentages of herbaceous taxa such as Artemisia andChenopodiaceae decrease gradually with altitude, while pollen from Pinus and Selaginellasinensis increase, indicating that Pinus and Selaginella sinensis are transported on longerdistance than Artemisia and Chenopodiaceae, from the mountainous area down to the plain.The latter suggests that differential sorting of pollen is occurring during transport in the riverwater. On the other hand, both farmland cover and crops pollen percentages increase withdecreasing altitude in both river catchments, which indicates that pollen percentage of thesetaxa is a good indicator of the extent of farmland. The total pollen concentrations in the twocatchments are15419grains/g in Qipanshan and20322grains/g in Tuoliang. The maximumpollen concentrations are found in samples from the largest and deepest ponds, whichsuggests that these ponds likely keep water and pollen content longer, resulting in a higheraccumulation of pollen grains in those ponds surface sediments. A correlation analysis of thepollen and land-use data shows that pollen percentages of cereals and other crops arepositively correlated with farmland proportions, while the relationship between arborealpollen and tree-shrub vegetation is poor. This study provides a valuable basis to detect androughly estimate the extent of historical human impact and land-use using pollen records from small basins in northern China.