A known amount of lycopodium spores was added to each sample to calculate the concentration of pollen ( grains / gram ) . pollen was examined at magnifications of 100 + and 400 + and identified using modern pollen collections and published atlases P2 - 1 :该亚带木本花粉的浓度达到了9 . 79粒克,而草本植物花粉的浓度相对于p1带有所下降,气候条件较好,植被为草甸草原。