Valentines Day has brought weather warnings for approaching Storms Dudley and Eunice later this week. Dudley is likely to cause damage in the Grampian area of Scotland and Storm Eunice is tracking across the centre of the UK. The warnings include damage by fallen trees which is a common hazard both in urban and especially exposed rural locations in Scotland and the north and east of England. Forestry plantations have already suffered badly already this year from winter storms, with an estimated eight million trees blown over and may more damaged. It is too early to say if this is a record storm season but the damage to forestry is substantial and as the UK rushes towards larger land areas under woodlands there may be a reason to stop and think of how climate change and more severe wind storms will impact on the new trees.
Uprooted conifers at Bolam Lake, Country Park, Northumberland following Storm ARWEN.
(The root system is shallow and in the form of a large plate)
A visit to Northumberland last month highlighted the wide extent and severe impact of this storm. The most interesting aspect of this was the way in which conifers were more severely damaged than large deciduous trees. The Bolam estate near Morpeth was landscaped by a benevolent landlord in the early 19th century. John Decies, later Lord Beresford, employed local people in order to boost to the rural economy and help to alleviate poverty. A stream was dammed and mixed tree planting attractively arranged around the newly created lake. The planting is dated to 1820 but it is not clear if the wind blow pictured above is amongst these older trees. What is clear is that the main reason for the widespread damage is that the tree roots have formed a plate which is often the case with exotic conifers, especially if soil conditions are imperfect. Soils which are wet for long periods or have a dense clay as a subsoil, tend to form a plate. With high winds this is levered out of the ground and the tree collapse into the adjacent standing timber, creates a domino effect with the wind cutting a swath through a forest. This effect can be massively increased by the land topography such as a valley with the wind acting as in a funnel. During Storm Arwen winds were regularly in excess of 90 mph. In contract deciduous trees tend to form a root ball which allows the tree to rock and survive rather than topple as happens with a root which is shallow and plate like. Deciduous trees can of course be felled by high winds especially in summer when a leaf canopy adds wind resistance.
Wind blow in a funnel after Storm Arwen in a Scottish coniferous forest
New saplings planted in Bedfordshire February 2022
There are lessons from these storms for foresters, land managers and those who are desperate to plant trees in the landscape for good climate change reasons. However, does this unprecedented run of storm mean a more cautious approach: there is a strong likelihood that these storms will be become more frequent as climate changes.
These events have brought the power industry into the discussion as overhead lines across England and Scotland were damaged leaving 112,000 homes in NE England without power, and 80,000 in Scotland: trees and overhead cables do not mix well. For those wishing to plant new fast growing conifers, the damage from winter winds on exposed sites is yet another factor to think about.
There are varying figures for the survival rates of new planting especially from whips or saplings, with drought the main enemy. The accepted figure is a loss of 30 percent of new saplings in the first year. Lots of variable factors come into play but large scale planting by volunteers is very vulnerable to drought as the watering of individual trees is impossible. A dry spring and summer after winter planting can be deadly.
The aim of every organisation planting new woodland sites is to maximise community involvement. The volunteers who planted the above tree saplings, braved strong winds, occasional rain, and a lengthy walk to the site. There was no lack of enthusiasm but how many will be around next year.
Planting schemes do factor in a substantial loss in the first year and the mix of species is deliberate. Experience has shown that popular, willow and cherry saplings do well: beech, and oak less so. In regard to wind blow the Scottish example would indicate that larch and Norway spruce are vulnerable.
(The title of this Blog comes of course from Shakespeare, As You Like It , Act II, Scene VII}