Proxy Data from Pollen Cores

4.1.e    Proxy Data from Pollen Cores

Pollen Cores in Ontario Lakes – 9,000+ years of history in sediment!

Pollen grains floating through the air land on the water in and sink to the bottom. Pollen grains are recovered in cores of sediment in the bottom of lakes. Sediment cores are collected by drilling and using hollow tubing in sections.

The cores are removed and kept in labeled sections similar to the ice cores and rock cores taken for scientific or commercial mining explorations. Regular sampling techniques are used to determine which pollen grains are found in each level of the core. The pollen concentrations at each level of the muddy sediment also indicate the dominance of the species of plants- trees or grasses that have airborne pollen in the area around the lake.

Source: J.McAndrews, University of Toronto. 2000

Questions:

1. How many centuries of data are shown? When was the last glacier here?
2. What 2 major influences changed the pollen concentrations shown?
3. What are the 4 biggest changes in species in the last 150 years? Why?

Research:

1. In which ecozone are these species found in Ontario ?
2. Which species was the most dominant as “pioneer” species?
3. What major group of pollen grains may be missing from these studies? Hint check the design of conifer pollen grains