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4th February 2010

Recent wildlife sightings by members of PNHS

 4th February 2010
Jack Snipe
Barn Owl
Long Tail Tit


The Aspen and the Beaver   Joe Greenlees

Joe gave a lively and humorous talk on the work of BULB to regenerate the Aspen tree in the Scottish countryside. He described a tree with a character as exuberant as his own, held in check by the exigencies of the Scottish environment!

The Aspen, a member of the Poplar family, is a beautiful slim tree with leaves,  which shimmer and tremble in the wind. Its Latin name reflects this famous property: Populus Tremula. The leaves produce spectacular autumn colours of yellow, orange, copper and red.

Although it grows abundantly in many cool northern climates, particularly famous in North America, it is not common in Scotland. Joe has set up a community programme to address this, and aims to re-introduce the Aspen in the Lowland belt of central Scotland.  BULB stands for Biodiversity Unlimited Lochwinnoch Branch, where the community group carry out this work.

Joe began by showing a photo of a typical position for an Aspen tree, hanging on a rocky cliff, in the Loch Sloy area.  There are only around 8 trees in Renfrewshire, and BULB’s aim is to collect roots from gullies and crags in neighbouring areas, such as Aird Meadows and Millport in Ayrshire and propagate them to plant locally.  The Aspen will not re-root from twigs, but needs roots of pencil thickness. From these, however, prolific growth can be generated. One root can produce 30 – 40 bulbs which will sprout in 6 weeks, and be ready to plant.

BULB has advertised via the local newspaper looking for possible sites to grow on the trees, but warn that the Aspen can be very invasive: “a bit like Japanese Knotweed”! It is not recommended for planting in gardens, because it tends to produce extensive layering root systems. This is the main way that the Aspen regenerates in the wild, and can send out layering roots for hundreds of metres. Suckers can take nutrient from the parent plant for 25 years. In contrast, the Aspen flowers and produces seeds only rarely, once every 10 years in Scotland. It is estimated that there may be less than 400 genetically different Aspen trees in the UK, the rest being clones, such is the power of its layering. One might say that the Aspen is the oldest growing organism, up to 8 thousand years old for the same genetic plant.

Given the prolific nature of its rooting system, Joe addressed the question of why the Aspen is not more abundant in Scotland. The answer lies in the intensive farming of a small country like ours. The delicate shoots are mown off, or eaten by grazing sheep before they get a chance to mature. Moreover, the Aspen tends to be squeezed out of light by more robust tree species. It also needs around 4.5 hectares of Aspen woodland to support the insect life specific to the tree.

The Lochwinnoch group have made considerable progress in its re-establishment. A revolutionary type of growing pot has helped greatly in producing ample roots for propagating on. Called the Australian airpot, it has a honeycomb design, and is made out of recycled milk bottles, with holes throughout that the roots can grow through. This prevents roots becoming pot bound and allows excess roots to be trimmed off for propagating on. Joe joked that he now has the potential for 48 thousand new Aspen trees.

Groups expressing interest in growing Aspens include the road contractors Amey, who have asked for straight trees that will not produce lots of suckers, and will turn attractive red leaves in autumn. Transport Scotland are interested in experimenting with using the trees to stabilise the land round the Rest and Be Thankful area, and the Aspen may have good potential for greening derelict sites because of its propensity for  sucking up contaminants like mercury. Scottish Native Woods have done a survey on Aspens, that should soon be on their website. It will show both cloned sites and planted sites. The Aspen Brittle Moss has been made a UK BAP species.

Joe’s talk created much interest and queries. Why,  people asked, given that the Aspen is so prolific, is it not more successful? Joe illustrated how it can be very successful in certain environs. For example in North America, following fires, thousands of Aspen shoots are thrown up, and in Yellowstone there was a boost in Aspens after wolves were re-introduced because the Elks moved out! They had been grazing the young shoots previously. In Scotland, however, infrequent flowering and seeding, plus overgrazing and mowing prevent adequate copses of Aspen flourishing.

There was only time for a brief mention of the Beaver, a species which co-exists closely with the Aspen in cool climates like the wilds of North America. Joe believes that there are some sites in Ayrshire that would be suitable for re-introducing the Beaver, alongside his Aspens.

Altogether this was a lively and thought producing talk.

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