Download Park Grass: testing new ideas on an old

Encouraging scientific debate: comics written and reviewed by young learners
comics
BBSRC Public Engagement Awards 2009/10
Topic: Park Grass; testing new ideas on an old experiment
Mentor: Dr. Jonathan Storkey
The Park Grass Experiment.
This is Sir John Bennet Lawes (left). He was a scientist and a
business man who lived between 1814 and 1900. He decided
to set up some field experiments at Rothamsted to study the
effect of fertilisers on the yield of different crops. One of those
experiments is in a hay meadow and is called the Park Grass
Experiment. It is made up of lots of plots with different
combinations of nutrients (including nitrogen, phosphorous
and potassium). An unexpected result was that one of the
fertiliser treatments was making the soil more acid so chalk has
been added to some plots to account for this effect.
Plants on Park Grass
The most striking thing about the Park Grass Experiment today is the contrast in the kinds of
plants growing on plots with different levels of fertiliser and chalk. You can even see these
differences in this photograph of the experiment taken from the air (right). Because the
experiment has been running for so long, only plant species that are adapted to the specific
conditions of each plot now survive there. For example, less buttercups are found on plots that
are either very acid or have lots of fertiliser added.
Evolution in action on Park Grass
Some plant species are able to grow on lots of different plots on Park Grass. One
example is sweet vernal grass (left). This is pretty amazing if you think about it
because it means they have to survive in environments that are very different. How do
they do it?? Well, plants of the same species can look very different on different plots.
This can be because they are responding differently to the local environment.
Imagine two people; one only eats cheeseburgers and the other bananas. They
would end up looking very different! The other way plants can survive on different
plots is to adapt. Natural selection is at work on Park Grass. In a given plot,
individuals of sweet vernal grass that have a genetic make-up that results in
characteristics or 'traits' that do better on that plot will produce more seed which will, in
turn, inherit those favourable traits. This can result in the genetic code of populations
on different plots diverging. If this divergence results in reproductive isolation
(populations on different plots stop crossing with each other), we are witnessing
evolution in action!
Glossary
Adaptation: Modification of an organism or its parts that
makes it more fit for existence under the conditions of its
environment
Natural selection: Natural evolutionary process that results in
the organisms best suited to their environment having the best
chance of survival and passing on their genes to their offspring.
Trait: An inherited characteristic.
ROTHAMSTED
RESEARCH