
On Thursday 20th November, the Year Nine Museum Studies group were invited to attend a lecture by palaeobotanist Jennifer McElwain on "Trees Through Time". The group are very privileged to be working with the Arboretum this year on a project developing new signage, and the talk formed part of a series of visits and workshops which are developing their thinking and understanding of trees, arboreta, and public engagement.
The talk began with an exploration of what makes a tree - Jennifer explained the categories were not completely clear cut, but usually a tree would have a woody, self-supporting stem, be perennial, and have a crown. She also pointed out that a forest is not simply lots of trees together but a dynamic system, in which trees are the dominant part.
She explained how trees have evolved significantly over time, and we looked at the earliest fossils of trees from the Devonian Period, and the earliest known specimen, from Devon in the UK. Trees at this time reproduced with spores, and did not have leaves. As time went by, leaves and seeds appeared.
She looks in her research at "stomata" on leaves and how the numbers of these increases when carbon dioxide levels decrease, and vice versa, so it shows how trees are witnesses to climate change. She also spoke of the limitations of trees - how for example, in modern day Greenland, it is largely too cold for trees, just as in desert climates, it is too arid and hot.
We looked at a recreation of what Greenland was like in terms of forestation in Jurassic times, and how fossils and an artist's work helped to create illustrations of the forests which abounded there at the time.
Finally, she looked at trees now and how well they respond to pollutants. She found that evergreen trees seemed to be more resistant to pollution in the environment than deciduous trees which she dubbed as having a "live fast die young" strategy!
It was a fascinating talk, and we will really look forward to seeing what ideas it has planted in the minds and imaginations of our Year Nine group as we continue work with the Arboretum and Dr Lauren Baker this year!