Fossil pollens

The study of pollens can reconstruct the history of vegetation in the past, and therefore of climate changes in time. For example we can imagine a fossil lake, preserved in different sediments, just like a filing cabinet with many drawers: each layer is a drawer containing the pollens of all the plants that grew at that particular time in the surrounding area. There are plants, in fact, that are considered climatic indicators – in other words they live in a particular region only if the climate is suited to their needs. For example oaks, hazel trees and linden trees which are all broadleaf trees, only live in temperate-warm climates and will never be found in regions with a rigid climate. Fir trees and beech trees instead, live in regions with a fresher, humid climate. In regions with a cold continental climate, only some types of grasses can be found, which form ecosystems such as the tundra or the steppes. If the climate of a particular region changes in time, obviously also the vegetation shall change and shall follow the various climatic oscillations very closely. This is exactly what we can see when we study the evolution of vegetation in a fossil lake or in any other deposit of sediments. Once a suitable area is identified, samples are obtained by drilling and core boring. Once the samples are extracted they are taken to a laboratory and treated with chemical agents in order to eliminate any excess organic and inorganic fraction, and finally the pollens are obtained.
Subsequently,  with the help of a microscope, a detailed analysis will help to recognize the various species of plants that were present in the area and therefore reconstruct the climatic oscillations of the past. The data that are collected, are then summarized in diagrams that visually represent the vicissitudes of the various historical periods. The next steps of the analysis consist in attributing a relative age to each climatic phase, and following the sequence of the events that have taken place over the centuries.

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