Source and distribution of pollen in the surface sediment of Daihai Lake, inner Mongolia

Daihai Lake lies in the transitional area from semi-humid to semi-arid region, and also in the north margin of the East Asia monsoon. The analysis of 65 pollen samples from the surface sediment of Daihai Lake and alluvium of its inflow rivers revealed the characteristics of pollen distribution and different transport vectors. Most pollen grains in Daihai Lake come from its inflow rivers, although rain-out and wind are also important. Activities of insects, birds and humans may also carry pollen into the lake. The pollen assemblages are consistent with the regional vegetation in general. The variance of pollen assemblages in different parts of the lake reflects changes of local vegetation near the lakeshore. Pollen concentrations in the lake sediment surface are lower than that in fresh alluvium in its inflow rivers, and the highest percentages and concentrations of major pollen types mainly appear in the margin part of the lake. DCA demonstrated that there are more similarities between lake sediments and the inflow rivers than there are differences.