I have been thinking a lot recently about the toll that storms have been taking on local trees. Adjacent to my house on The Park are ageing larch, Scot's pine and a poorly gaggle of elm, yes elm, more of that in a moment. I have photographs as well as my memories of these trees when we moved here ten years ago. There were many more of them. I reckon something like twenty of the larch and pines have fallen or been felled because their already unnatural angle and bends and splits in their trunks had rendered them somewhat hazardous. They were growing on land just over our fence in what may have been a managed plantation sometime ago but has now become unmanaged scrub. It isn't pretty but is much used by birds, small mammals, bees and butterflies. Despite its lack of obvious beauty when the larch turn green in spring and the grasses and shrubby understorey comes back to life it has value. There are reasons why the trees are coming down. These reasons include very shallow soil so the trees have exceeded their roots' ability to hold them straight and perhaps more importantly their age and height. They are well beyond the age and height (and general condition) at which they had any commercial value, which is undoubtedly what was in the mind of the planter. They have become bent, they stoop like an aged man with arthritis. Recently I managed to get hold of a disc of wood cut from a freshly felled larch and also from an elm brought down by a storm in January. Counting the annual growth rings revealed that the larch, which were inter-planted with the pines are around 90 years old. That interested me and caused me to think about when that planting would have taken place. In the late 1920s, a bit of post WW1 enterprise no doubt. The elm was around 83 years old. That was a surprise. We have so few remaining English elms. When I referred earlier to a poorly gaggle of elms that is what they are. There are a few of substantial height (around 20-25 metres) but all around them there are weakly and dead examples of about 5 metres. These weaklings are no doubt the result of seed and vegetative regeneration of parents that have succumbed over the years due to pest and tempest. My understanding is that elm can grow to about 5 metres before the beetle that spreads Dutch Elm Disease will find the tree as the beetle prefers to fly at about that height. So the presence of a tree, albeit now brought down by a storm, that managed to live through the peak time of infestation in the 1970s is in its way important. Intriguingly there are a few more examples of trees standing at 20-25 metres in the group. How come? Are they resistant to the disease?
I would like to widen my discussion of trees at this point. Wherever I have travelled in the world I cannot help but observe that whatever the geology and climate the presence or even the absence of trees puts the finishing touches and defines the landscape. Among the plants it is only trees that have the size to make a landscape scale mark on the underlying geological canvas.
How many species of tree are there in the world. There is still debate about this but a reasonable working estimate is 60,000 with hundreds of hybrids just to complicate things. Most occur in the tropics. The UK might have a hundred or two species but most of these were brought here from foreign parts. When thinking about the ecology of small spaces one might be very lucky to find a few tens of species even including the imports. It is not very long before the occurrence of tens of species of trees on a piece of land qualifies as an arboretum.
So care is needed in small spaces to maintain good tree diversity, that is examples from different tree families. This becomes more and more important as the number of pests and diseases arriving in the UK seems relentless. Pests and diseases may well attack closely related species so the impact and damage may be greater than just the species where the pest or disease is first found. International trade in trees may increase the number of pests and diseases introduced and climate change may allow those pests and diseases to gain a permanent foothold. Choosing and managing new tree plantings requires a lot of thought and ongoing care.
Given all of these factors working against trees we really don't need a further one. Returning to my on going them explored in these blog pieces, somehow some plants, including trees, have become demonised or at least unloved and undervalued. If push comes to shove when some species are seen as a nuisance or of little value any proposals to clear or in the case of trees fell may arouse very little concern or resistance from local people. A case in point is the sycamore (Acer psuedoplatanus). We have them on The Park in relatively small numbers but those examples that we do have are quite mature. They may grow to a height 35 metres and 400 years old. They are very wind tolerant and so form good wind breaks. I have often heard sycamore referred to as a weed tree. I am not entirely sure why. I suspect it is for two reasosn. Firstly the sycamore was not native to the UK but has been here since the Middle Ages (or maybe Roman Times). Secondly its winged seeds when caught by the wind can helicopter hundreds of metres away from the parent tree. It spreads like a weed. The winged seeds are really fascinating. Each winged package contains two seeds, increasing the chances of new offspring. I know from our own garden which is about 100 metres from sycamore in three different directions that they land and germinate every year. We pull them out because we cannot have them growing all over the garden. They even pop up from time to time in the lawn. When they land and germinate in not such obvious places for example in the bottom of our hawthorn hedges they can be 30-40 cms., tall before they become obvious. Despite all of this the sycamore produces excellent timber (for kitchen ware and furniture), provides habitat for some insects (including aphids and hence ladybirds, two species of moth - not the hundreds of species found in an oak tree). It is an excellent source of pollen and nectar. It is related to the field maple which is deliberately planted in large numbers in gardens, parks and other public spaces. Spare a though for the sycamore and celebrate its visual impact on our landscape and admire its well evolved and successful seed dispersal.