Ash is about as native a species as one could wish for. Pollen and fossil wood fragments have been found in several periods preceding the current one. It is also a species which appears the most intimately linked with human activity.
During the early Holocene (circa 11500 BP - 5000 BP) Ash appears to have been an uncommon but widespread tree. However, its real expansion came during the later Holocene (5000 - 500 BP); stimulated by human opening of the British Forests. Human settlement and clearances, therefore, created the conditions of scrubland and hedgerow that enabled Ash to flourish.
Cultivation.
Ash grows best on deep, moist, fertile soils, especially where there is a high nitrogen content. Where mature trees exist, there will be an inexhaustible supply of new seed.
Our ex-farmland site is covered in nitrogen-fixing clover and has several mature trees in the surrounding hedgerows. Little wonder, then, that new seedlings appear by the thousand wherever we perform coppicing operations. Fortunately, Ash seems a very organised tree and new seedlings tend to appear neatly aligned within our existing rows.
The main pest of Ash is the Ash Bud Moth, which often causes the leading shoot to abort and results in multiple leading stems. Grey squirrels are rumoured not to like it, but rabbits love the bark. We put plastic guards around our trees: to stop them scraping off the bark. They simply dug down to the roots, however, and chewed them off instead. Thus resulting in the only Ash trees that I have ever known to die. I don't like rabbits.
Ash definitely needs damp conditions: the very dry period in early spring 2007 saw our Ash struggling to come into leaf.
Ash is a very strong light-demanding species. The crown should be continually free from competition to grow quickly and produce quality wood ( 4 - 16 rings/inch). Once constrained and neglected Ash does not respond to further thinnings.
Planting and Aftercare.
Browsing damage
Rabbits will strip the bark from young trees at any time and dig out and eat the roots in severe winter weather. They will also browse on the newly emerged coppice shoots. Newly planted trees will require tree shelters as a minimum. Coppicing operations will require good quality rabbit fencing to ensure acceptable levels of regrowth.
Spacing
Natural regeneration will often result in 50,000 seedlings per acre, so plant as densely as you can afford. Aim to plant at 1.5 metre intervals along each row and between every other row. Plant at 2 metre intervals between the alternate rows to be used for maintenance access. Dense planting will allow for selective felling/coppicing on each cycle: the trees left standing providing both side shade and protection for the new coppice shoots. Ash will regrow in a multitude of bent and twisted stems in an exposed situation; making it very difficult to saw up for firewood logs or to split.
Coppiced Ash regrowth
exposed situation sheltered situation
Formative Pruning.
Ash has very brittle timber, and is prone to losing branches in even fairly light winds. The loss of the main growing tip (or leader) results in a good deal of forking. Trees being grown for timber must have any multiple leaders removed. If not left for too long, side branches can be removed easily with secateurs or loppers. Care should be taken not to damage the Branch Bark Ridge or Collar when pruning (see the Formative Pruning section in the General Planting & Aftercare page). Careful thinning and pruning is essential to produce straight Ash poles with 4 - 16 rings/inch.
Coppicing
I usually make an initial felling cut with a chainsaw and then tidy up the stool with a large pruning saw. I find that this leaves a tidier, cleaner stump. I make the maiden cut at around 10 years, with a subsequent rotation of around 8-10 years. This produces lots of nice, reasonable diameter, logs which fit into our woodburning stove and which season well; with only those 6" or more needing to be split.
Although Ash doesn't usually come into leaf until late April/early May, it will still be producing new wood (Xylem) during late Winter/early Spring (see Timber Properties below). To avoid the excess build-up of resin on the equipment, I tend to cut the Ash early in the winter and then leave logging them up until I have more time in the late winter/early spring.
felling cut tidied stool
Timber Properties.
Ash is one of the last trees to come into leaf in the spring. This is due to the way in which it lays down new wood. Ash has opted to lose all of its water bearing vessels each winter and to produce new ones each year: most of these in spring with only a few in the drier, summer months.
This means that before its leaves can open, it has to grow new wood in the early spring. The benefit of this approach is that Ash is less prone to frost damage in winter and spring and to air pockets (or "embolisms") in summer. Embolisms disrupt the supply of water, and hence nutrients, from the root to the leaves.
The wood laid down in summer is much more dense and fibrous that that of spring. Ash wood is therefore said to be "Ring-porous": rings of porous wood are alternated with rings of drier, more fibrous tissue.
In consequence, Ash grown in good conditions will lay down a good deal of relatively dry (37% moisture at felling), dense, strong wood. In addition, Ash stores food reserves within the wood (Xylem) in the form of Oleic Acid: a fatty acid associated with olive oil. This makes Ash timber particularly flammable and, therefore, well suited for firewood.