This will be done using a field of science known as palaeoecology, which is the study of past ecosystems and environments.

In palaeoecology, scientists use biological and non-biological materials (such as fossils, lake sediments and ice cores) to indicate what the environment might have been like many years ago.  We aim to use this information to set targets for the restoration of biodiversity in Surrey.

In this blog, Ben provides his first report from the field.

In early May, myself and a team of researchers from University College London (UCL) collected two sediment cores from ponds on Chobham Common. The ponds that we chose to take the cores from have existed on the Common for a few hundred years, forming part of a central wet heath area that was visible on old maps dating from the 1800s. In order to take the samples, a long tube of around three inches in diameter is pushed down into the base of the pond, deep into the sediment, until it can’t be pushed down any further. A hydraulic seal is created before the tube is raised up back to the boat, in order to make sure the sample does not fall out the bottom of the tube.  After the core is safely brought to dry land, it is cut into 1cm slices, which are bagged up for analysis back at the labs later on.

Take a look at the video below to see us in action on the Common, and hear a little bit more about how palaeoecology works from UCL’s Professor Helen Bennion.

We plan to examine four indicators of environmental change, dating back over 200 years, in the array of 1cm slices we have collected.

1. A type of microscopic algae called diatoms are commonly used by palaeoecologists to look into the past. They are very sensitive to environmental conditions, so will only live in very narrow ecological niches. This means that if a particular species of diatom is present, you can get a pretty good idea of what a pond was like in the past. Diatoms can be used to look at a variety of chemical and physical variables, such as pH, water temperature, salinity and more.

2. Spheroidal Carbonaceous Particles or SCPs are an artificial type of ash that is only produced by the combustion of fossil fuels, and this can also be found in lake sediments. The presence of SCPs in a sediment core can help provide some rudimentary dating, because the first occurrence of them will coincide with the industrial revolution and the beginning of coal burning in that area. The increase over time can also give some insight into the possible impact of periods such as the 1950s, where there was a dramatic increase in the amount of fossil fuels being burnt.

3. Macrofossils, which are usually the remains of plants and invertebrates, can tell us about the local ecology and species assemblages of the area over time. Unlike pollen, macrofossils are quite large and do not move very far from the organism that produced them. The insights provided by macrofossils can give a good picture of the vegetation in and around the water body.

4. In order to look into the fire history at Chobham Common, we will also be examining the macro-charcoal remains in the sediment core. Charcoal is deposited in the sediment when wild fires occur, and these have been frequent throughout the history of the Common. By counting the macro-charcoal, we can learn more about the frequency and intensity of these fires over the history of the site.

This analysis will soon get under way in the UCL labs, where the samples are being stored in a cold store to prevent degradation. Over the course of the summer, we will produce some preliminary results and begin to reveal some of the history of Chobham Common.

Stay tuned to learn what the waters of Chobham tell us…