Ecology of the past

So we’re back from a hot and humid Ecuador to the joys of a British winter. Ecuador is an amazing country and the diversity of the flora and fauna surpasses anything that I have experienced before. It’s also very strange to be working at an altitude twice that of Ben Nevis in a t-shirt and shorts (and wellies). My main focus during our fieldwork was recovering lake sediments from a location previously visited by our research group near the town of Cuyuja (pron: Cur-you-ha).

Lake Huila (although this seems a bit of a grand title for a pond that cows use) is located near the village of Cuyuja in the Quijos Canton of the Napo Province in central Ecuador. The lake is situated on cleared farm land that is surrounded by dense cloud forest at an altitude of approximately 2600m. The lake is about 35 metres in diameter with a maximum water depth of about 1 metre, although this is very dependent on the amount of recent rainfall.

In order to recover sediment from the lake we used a Livingstone corer from a floating platform (diagram) to remove 1 metre sections of sediment at a time, reaching a maximum depth just shy of 3 metres before we couldn’t drive the corer any deeper. This process was done twice in order to get more sediment and a full recovery at the join between previous core drives.  When these cores arrive back in Milton Keynes they will then be logged, dated and sampled ready for pollen and charcoal analysis.

We also took several surface core samples of the lake and nearby bog, which we hope to be able to correlate with each other and analyse in order to find out when humans started inhabiting the area, which should be evident with a spike in charcoal (from clearing the forest) and an increase in maize and yuka pollen from farming. We also undertook a detailed cross section of the lake and bog area and a description of the modern flora present.

The coring also turned up several ash or tephra layers (which isn’t surprising as Ecuador appears to be just a series of massive volcanos) which we hope to be able to correlate regionally (possibly the nearby Antisana) and through time.  Although at the moment we have little idea how old the lake sediments are, they could be any age between recent and about 200,000 years old as this is the age of the volcanic basement rock in the area.

Our initial interpretation of the lake is that it is a kettle hole lake formed during a period of retreating glaciers (any glacial geomorphologists out there?). Kettle hole lakes form when a large block of ice falls from the front of a retreating glacier and is then buried in glacial outwash, when the block melts a depression is formed which becomes a lake or bog.

So, Merry Christmas and a Happy New Year to everyone and see you next year for core splitting fun and pollen prep.