The Tree of Heaven Project - Ailanthus Altissima

THE TREE

Ailanthus altissima /eɪˈlænθəs ælˈtɪsɪmə/, commonly known as tree of heaven, ailanthus or varnish tree is a deciduous tree in the family Simaroubaceae

Unlike other members of the genus Ailanthus, the Altissima is found in temperate climates rather than the tropics, and native to central and north east China as well as Taiwan.  From the 1700s onwards it has been cultivated in North America and Europe.

Its appearance most resembles the European Ash, with its pale, yellow white timber and its fans of pinnately compound leaves.

 PEST

The Ailanthus is not a popular tree, not amongst horticulturists and not among the random people responding to my social media posts and blogging.  It is extremely invasive when it is planted in non-native places it upsets the local ecosystems in numerous ways.  Not only does it propagate much faster than the native species it has crowded next too but also secretes chemicals into the soil to kill off its rivals and any animal species it might consider a threat, potentially leading to extinctions and/or negatively effecting bio-diversity.

In the urban environment, where our tree had been growing for 50 years plus, the tree can cast itself across various gardens and parks, causing the same problems as in rural areas plus it can hit the built environment.  Numerous cases have been recorded of the Ailanthus tree spreading its roots under the foundations of buildings, causing damag to the houses and also sewer systems and pulling up pavements.

Its quite a git.

The Royal Horticultural Society advises “If you already have these species in your garden or on your land, you are not likely to be prosecuted simply for having them. However, you are advised to control them and, for those 36 plants listed by EU, you are required to take all possible steps to remove them, even if you didn’t plant them. It is also your responsibility to ensure that they are not allowed to spread.”

EU Regulation lists the Ailanthus as an Invasive Alien Species. This legislation still applies in the UK. It lists Ailanthus altissima as one of 36 plants that you should not plant or cause to grow in the wild but in addition are banned from sale and gardeners possessing them should undertake measures to control them.  

The Tree of Heaven Project - Milling Day

I was back in Kensington today to help mill the Ailanthus tree that was felled last week. And by help I mean marking up pieces of tree with chalk and watching experts convert it into usable timber. I learnt alot today and I am optimistic that the yield has been maximised.

The mill and the Milling

The milling was hard going, the sapwood is very gummy, especially just beneath the bark and the chainsaws clogged and became blunt after two 2 metre passes. The mill operators were slowed down considerably and needed to return the following week to finish the job.

Shakes or cracks in the timber are the most common challenge when it comes to converting threes into usable timber.  Heart shakes occur along the centre of the tree, where it’s the oldest and most fragile.  The middle boards, and especially the very centre board is susceptible to this and when we placed our central board onto the sticked pile there was a very loud crack as the board parted down the middle.  Although this a challenge to the yield, the central board obviously very wide compared with the outer ones so two lengths of usable timber can be taken either side of the crack.

The other boards fared well with the exception of a few felling shakes at their extremities, and but only 10 to 15cm from the ends. Felling shakes caused by the trauma of the felling process

 

The Timber

As a European furniture maker, I know very little about the Tree of Heaven and in the next few weeks I endeavour to educate myself.  I had read that the timber resembled European Ash and was noxious when milling.  As we started to mill through the body of the trunks, the characteristics of this Ailanthus tree started to reveal itself. Although, the timber was not smelly at all when cut, the timber did indeed resemble the pale, grey-yellow of Ash.  The very heart is a golden brown and the sapwood paler than the main body but similar enough that some will be robust enough for use.

 

Yield

There are numerous blanks ideal for turning, especially those cut from the confluence of the limbs or trunk and limbs, where the timber is more colourful and varied in its figure. Elsewhere, there are potential greenwood working opportunities and at the bottom of the priorities, some rounds and odd shaped but small pieces for outdoor furniture.