This document discusses the use of pollen analysis to study climate evolution in a specific area by identifying plant species and their corresponding climatic conditions.
Extract
[...] Schemes : Scheme of a birch pollen grain Scheme of a spruce pollen grain 4. We have studied the distribution of pollen grains in a peat bog. The deeper a pollen grain is found, the older the pollen grain is. The following graph was obtained: Figure 1 : Distribution of pollen grains as a function of depth 5. To study the climate evolution in this area as well as possible, we determine which are the three species whose grains are the most numerous in the peat bog. [...]
[...] Reconstructing past climates using pollen 1. Document 1 specifies the plant species found in each biome as well as the necessary climatic conditions for the formation of these biomes. Document 2 presents the characteristics of pollen grains from different plant species. Or, we know that currently in bogs, we can find pollen grains trapped by moss thousands of years ago. By identifying the plant species to which these pollen grains belong, we can get an idea of the biome that was present at the same location in the past, and deduce the climatic conditions of the time. [...]
[...] 7. This sequence of events suggests that during the studied period the planet experienced a rise in temperature and atmospheric humidity. [...]
[...] The pubescent oak grows in temperate climates, it has a slightly higher requirement than other oaks in terms of heat. The oak is found in deciduous forests that have a temperate climate and average humidity. The beech needs humidity to grow and fears spring frosts. It also grows in deciduous forests. This allows us to reconstruct the evolution of the climate in the studied area: - In the past, the cold was so harsh and the humidity so low that only grasses could survive, no trees could grow. [...]
[...] We therefore obtain the revised graph as follows: Figure 2 : Distribution of pollen grains as a function of depth after revising the data 6. The pollen grains of the three species were found at distinct depth ranges. To confirm this, we used the raw values from the data table, applying conditional formatting and determining the depth range for which we have the largest quantity of pollen for each species. The depth ranges for the three identified species are: 0 to 2950 feet for fagus to 5050 feet for quercus to 5800 feet for poaceae. [...]
