The Climate Change Scenario of Willow

Willow Man sculpture beside the M5 in Somerset. CC © Copyright Anthony Parkes 

If you travel down through Somerset towards Devon and Cornwall on the M5 this Christmas, you will see the huge Willow Man on your right-hand side near Bridgwater. The Willow Man is a giant wicker sculpture made by Serena De La Hey. It is the South West’s equivalent to the Angel of the North. The local bird population has taken quite a liking to the ready supply of nesting material. The sculpture has needed to be spruced up a few times.

Willow Cultivation

The Willow used in the sculpture is made from Salix triandra ‘Black Maul’, a cultivar of the Almond Willow. It is more commonly used for basket-weaving. The cultivation of Willow for basket-making continues to this day on the Somerset Levels, despite the decline in the art elsewhere in the country.

Fast-growing Hybrids

Salix triandra is prized as a fast-growing species that readily lends itself to short rotation coppicing. It is the second most popular species for basket-making after Salix viminalis, the Common Osier or Basket Willow. The two species also readily hybridise with each other. Salix hybrid identification is the bane of a botanist’s life.

Willow Family and Groups

Willows or Sallows, Salix spp., belong to the Salicaceae family.

Milner divides Willows into 4 groups relating to their habitats, whether they grow on floodplains and riverbanks (alluvial), or not (non-alluvial), or are mountain species:

  • Group A: Non-alluvial Willows: Sallows, Eared and Bay Willows
    • Goat Willow or Sallow (Salix caprea); Grey Willow (Salix cinerea); Rusty Sallow (Salix cinerea ssp. oleifolia); Eared Willow (Salix aurita); Dark-leaved Willow (Salix myrsinifolia); Bay Willow (Salix pentandra).
  • Group B: Alluvial Willows: Long-leaved Tree-willows
    • Crack Willow (Salix x fragilis); White Willow (Salix alba – including Cricket Bat Willow, Salix alba var. caerulea).
  • Group C: Alluvial Willows: Osiers and Basket Willows
    • Almond Willow (Salix triandra); Common Osier (Salix viminalis).
  • Group D: Mountain and Dwarf Willows
    • Creeping Willow (Salix repens); Mountain Willow (Salix arbuscula); Downy Willow (Salix lapponum); Woolly Willow (Salix lanata); Dwarf Willow (Salix herbacea); Whortle-leaved Willow (Salix myrsinites); Tea-leaved Willow (Salix phylicifolia); Net-leaved Willow (Salix reticulata).

Awkward Seeds

Our two species fall into Group C as they grow on floodplains, the banks of rivers, streams and mountain torrents. This is a shifting environment in which fast growth is a definite plus. Salix seeds need to fall on bare ground and establish quickly. They have one of the shortest, or shallow, dormancy periods of any tree. This makes them an easy tree species to germinate. Unfortunately, Willow seeds are recalcitrant. They are regarded as awkward to handle and impossible to store. They are highly perishable. They die within days of dispersal or collection. They need high moisture levels to stay alive and will die even when preserved at low temperatures.

Vegetative Propagation

It is small wonder therefore, that vegetative propagation is preferred to seed propagation. Willows readily root in the ground. This carries the disadvantage that any resulting Willow tree will carry the genes of only its parent plant. Care has to be taken to mix populations when taking cuttings and planting.

Associated Fungi

There are over 3,900 Fungi associated with Salix species in the Britain and Ireland. This is the second highest of any native species, other than Birch (Betula). Some Fungi may be benign, but a number are detrimental to Willows. A few of the troublesome fungi are:

  • Black Canker, Physalospora miyabeana – a parasitic fungus
  • Various Leaf Scabs, Venturia spp.
  • Tar-spot or Black Rust, which attacks Willow leaves due to the fungus, Rhytisma salicinum.

Not Good for Cricket

Commercially cultivated species can also be vulnerable to the Watermark bacterial infection. It particularly affects Cricket Bat Willows. This is decidedly not good news for Somerset County Cricket.

Insects

A large number of insects find Willow very tasty. It provides a valuable, early nectar source for bees. Some 839 invertebrates depend on Willows (that is even more the much celebrated Oak for biodiversity). Of these species, 314 have an exclusive taste for Willow. This can be both a blessing and a curse. Insects are vital for a healthy ecosystem, but some can also introduce disease. The climate change scenario heightens the risk for a species without a large gene pool.

Climate Change

Salix could prove one of the most valuable species as we plan and face the climate emergency. Unlike many other tree species, Willow copes well with a waterlogged soil. Even its resilient roots will die if left permanently under water.

Benefits for Smallholders

Willow is particularly appreciated by smallholders as a shelter belt in winter, and shade in summer for livestock. Its fast-growing hedges can divide a field or act as an enclosure. Willow can provide both fodder and biomass. The Salicin in Willow has recognised medicinal benefits as a natural source for Salicylic Acid (Aspirin). Sick animals happily self-medicate, if Willow is available in their field.

We seem destined to appreciate Willow even more in the coming decades.

References and Further Reading

Forest Research (2019): Short rotation coppice. Last accessed 11 December 2019.

Johnson, Hugh (2010): Trees. A lifetime’s journey through forests, woods and gardens. 4th Edition. Mitchell Blazey. Octopus Books reprint. New York. (The Willows pp.190-193).

Johnson, Owen & More, David (2006): Collins Tree Guide. The Most Complete Field Guide to the Trees of Britain and Europe. HarperCollins Publishing. London. (Willow pp. 164-171).

McCartan, Shelagh (2019): Raising trees and shrubs from seed. Practice Guide 16. Forest Research. Salix tiandra. Willow (Almond). Last accessed 11 December 2019.

Milner, Edward (2011): Trees of Britain and Ireland. Natural History Museum (Portraits of Native Trees: Willows and Sallows Salix spp. pp153-161).

Morgan, Sally (2019): All about Willow and its best uses for smallholders. Country Smallholding, 30 May 2019.

Morris, Steven (2018): Weeping for the Willow Man: beloved Somerset sculpture under threat. The Guardian. 17 June 2018. Last accessed 11 December 2019

Rich T. C. G. & Jermy, A. C. (?): Plant Crib. Salix. Last accessed 11 December 2019.

Stace, Clive A. & Preston, Chris D. & Pearman, David A. (2016): Hybrid Flora of the British Isles. Botanical Society of Britain & Ireland. (Salix pp. 106-142).

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