Charles Darwin's 'Lawn Plot Experiment'

by Irene Palmer, March 2013.

Darwin's tree sketch showing diversification over time.

In 2009 Orpington Field Club members set up a three-year survey on Downe Bank with the aim of repeating the 'lawn plot experiment' that Charles Darwin described in the Origin of Species. The initial group included myself, Jan Hendey, Geoff Bird, Rosemary Ferguson and Beryl Hodge.

Paul Glanfield and Grace Green constructed a square plot 4'0" x 3'0", similar to the plot Darwin had described. The Field Club recorded the different species that grew within the square on several occasions during the next 3 years. We compared our results with Darwin's study and a similar recent study recently carried out by English Heritage on the lawn at Down House.

In view of the interest in our project, the team are surveying a new experimental plot (2012-2014). Unfortunately Geoff Bird has been prevented by ill health from continuing to record.

Charles Darwin, On the Origin of Species, Chapter 3, 'Struggle for Existence'.

1856 — Darwin recorded 20 species (mainly grasses) that belonged to 18 different genera in 8 orders. His main aim was to demonstrate the effects of competition in a simple way. His plot was left unmown and after three years 9 species had perished and coarse grasses dominated.
Darwin later referred to the same experiment in the section 'Divergence of Character.' He drew a sketch of a branching tree to illustrate how plant families, such as grasses, had diversified over time from their early ancestors to occupy different niches in the environment.

English Heritage (2005) began a survey in the orchard at Down House. They found a similar number of plants to those that Darwin found on his lawn.

2005 — Jane McLaughlin recorded 19 species and 16 genera in the orchard. These declined to 15 species over the three year period.

Orpington Field Club (2009-2011) carried out a similar study on Downe Bank.

2009 — recorded 40 species in 39 genera in 18 orders + 2 bryophytes
2010 — recorded 40 species in 38 genera in 17 orders + 2 bryophytes
2011 — recorded 36 species in 33 genera in 14 orders + 2 bryophytes

New species appeared and others disappeared during our study. A total of 46 different phanerogams + 2 bryophytes were recorded over three years, confirming Downe Bank's high biodiversity. The number of grass species remained constant but we saw an anticipated change in the habitat as it began to revert to scrub with plants such as Dogwood colonising and then to a woodland climax community.

A surprise visit from BBC Countryfile that led to a brief appearance by Jan Hendey and Irene in the 25th September 2011 programme. After filming at Down House the film crew arrived at Downe Bank as the light was fading in the early evening. It fell to Irene to explain our reasons for repeating Darwin's experiment on Downe Bank to the presenter James Wong, in brief gaps between aircraft flying overhead.