What can the pollen tell us?

• Vegetation is very sensitive to climate. Knowing what types of plants were present in the past can help us determine what the climate was like at that time. Scientists look at the habitats in which these or related species of plants live today to get an idea of what their habitats were like long ago. 
• Pollen found in the sediment gives a picture of the vegetation from the general region around the site where it was collected. It does not show a picture of vegetation from a single, specific habitat. Some of the pollen probably came from nearby plants, while some was transported from a greater distance after it was released into the air. 
• Since most plants produce pollen, the sediment will contain pollen from a wide variety of plants from the region. 
• Pollen accumulates (builds up) continuously. By studying these layers of pollen and sediment, scientists can reconstruct changes in vegetation over thousands of years and determine when and how quickly those shifts occurred. Some lakes even have an annual layer (laid down each year, similar to the way that trees add annual rings) that makes it possible to reconstruct short-term climate changes over tens or hundreds of years.