London’s October Storm: A Revealing Wind
The storm approaches
The “Great Storm” which hit London in October was a bit of excitement for some and a concern for others. Whatever your own experience of the storm last week, let’s consider how this natural event may have affected London’s wildlife; it divided their opinion too.
The wild animals of the UK are used to a bit of rain and cold, they couldn’t live here if they weren’t. Most have either waterproof feathers, warm insulating coats or strategies to sleep through the worst of the weather. Wind, however, I find a more interesting weather phenomenon. Wind can aid or disrupt bird migrations. It can disperse seeds and small animals such as ballooning spiders. A high wind puts many of our animals on their guard. Imagine being a nocturnal creature such as a badger, whose recognition of the world is based on smell and sound. Coming out in a high wind which whisks away smells and rustles leaves must feel like being in a black hole full of cymbals.
Poplar tree blown over in the storm
Wind can be a destructive force. Several wonderful old trees along the banks of the Thames were brought crashing down by the storm. Our first reaction is to think, what a shame. But storms are a natural part of life and the ancient woodland which once carpeted Britain would have seen many. When a tree falls down in a mature woodland, the space created in the canopy allows seedlings the opportunity to race towards the light and fill the niche. The health of the woodland actually depends on this; if all the established trees just continued to live forever, there would be no age structure or habitat variation, and the forest would stagnate.
Of course the banks of the Thames are a long way from the ancient woodlands we associate with Robin Hood. There is often not such a ready and eager source of saplings striving to take the old giant’s place. But nature is resilient and, if allowed and given time, this will still occur.
When a tree dies fungi and invertebrates eat away at it, and it slowly decays. The fungi and invertebrates living in the dead wood provide food for birds and other animals. Deadwood is an important component of a healthy woodland.
Several of the trees hitting the deck along the Thames caused a closure of the path. The wood will need to be moved. Increasingly, however, London councils are realizing the value of deadwood, and hopefully some of the timber will be moved only as far as the side of the path, and left for nature to take its course.
River path blocked by storm damage
The storm gave me an opportunity to investigate parts of trees usually out of reach, unless you happen to be a squirrel or a wood boring beetle. I wasted no time in peering into the ripped trunk a falling poplar left behind in the ground. I was looking at a cross section of a hidden world; a world normally of darkness and decay, the inner bowels of a wooden giant. The species I could see here would normally be covered over with layers of wood and bark, but have suddenly found themselves exposed. Soon, they will either burrow back into the remaining stump, or become a feast for an opportunistic predator such as a bird.
Ladybird fleeing the exposed wood
There were spiders guarding their now vulnerable egg sacs, beetle larvae chomping their way through the soft wood, woodlice tumbling from the cliff face of the newly severed trunk, ladybirds facing the prospect of searching for a new winter hibernating place and a beautiful golden mushroom, whose colours saw the light of day for the first time today.
Mushroom fruiting inside the trunk of the old tree
It is not only the centre of the trunk normally hidden from our view; the towering heights of the upper branches are another world usually beyond our grasp. Searching through the uppermost leaves, now carpeting the Thames Path, I discovered structures I hadn’t seen before, a variety of gall. Galls are abnormal growths of plant tissue. They are triggered by the presence of invertebrates who utilise the gall for their own purposes; usually living inside it and feasting on the plant tissue free from danger. In the name of science I opened one of the galls and used my field microscope to reveal the tiny squatters; aphids. The survival prospect for these disrupted plant parasites is actually quite high; as winter approaches these aphids develop wings and leave the gall in favour of other host plants. If the fallen tree is allowed to remain intact, they will probably simply make their exit as intended and move on, albeit from a basement flat rather than the penthouse. In this case they are fortunate to be city dwellers. If the tree had fallen in a woodland, the succulent leaves, and their insect tag-alongs, would be eaten by browsing animals such as deer.
An aphid gall on a poplar leaf
An aphid inside the gall, as seen through the microscope
The British are well known for our love of discussing the weather. I hope this article serves to convince you that we aren’t the only ones whose day can be totally upturned (in this case literally!) by the often surprising British weather.