Garden Tool Set

Wild Things 4 of 6 - Snowdonia

This week we’re in Snowdonia looking at lichen, junipers, and rhododendron.

Teeing off with the troublesome rhododendron. It is so invasive that it’s something that volunteers on Brownsea Island has taken decades to remove, with a special ceremony to remove the last one in 2011.
Introduced in the 1800s, it escaped via seeds from a Hampshire garden in around 1922. Its success is the speed of its growth, along with the toxic leaves that cannot be grazed by the local herbivores and that provide a deep canopy that allows through little to no light. If this wasn’t bad enough, the Rhododendron harbours a disease. The cells of the leaves are destroyed by the fungus-like pathogen called Phytophthora ramorum, leaving blackened remains. This disease travels through the air in sporangia, the same as the spores of fungi and some land plants. The disease, looks for weaknesses in the surface of the leaf to get into the plant, with a single individual able to kill a whole tree. We see that the only way to control the ramorum is to cut down the infected tree – and all of those around it.

The major casualty of this is the Japanese larch, starting in the South West in 2009 and moving through Wales, Northern Ireland and the Republic of Ireland by 2010. Therefore a removal of the rhododendron is occurring in Snowdonia and while this is made out to be the only culprit on the programme; the first discovery in the British Isles in 2002 was actually on an infected viburnum. Viburnum, along with rhododendron and camellia used to be the only plants infected prior to this discovery. More information on this disease can be found on the forestry commission website and the video below:

Next we’re with Sally for something altogether more lighthearted. One of the cool things about Wild Things is that its giving air to the wonderful organisms that are lichen. Lichen are thought to be the first organisms that made it out of the sea and on to land 1.3 billion years ago. Sally explains that the wet conditions brought by the westerly winds of the Atlantic create a temperate rainforest. One of the key indicators of rainforest is the lichen Sticta fulginosa, which occurs when there is on average more than 180 days of rain per year. On the map we see that this lichen can be found in Ireland along with westerly areas of England, Wales and Scotland. Oh and by the way, Sally explains that it carries quite a pong! Time is taken in this episode to explain that lichen are made up of fungi and algae. The fungi provides the algae with protection; the algae provides the fungi with food – an excellent symbiotic partnership.

We’re even treated with a display of what’s called lichen substances; the chemical compound made by the fungi to protect the vulnerable algae from UV radiation. Awesomeness right there. I really hope that Wild Things is granted a second series.

Trevor is then on the lookout for Juniper up Mount Snowdon itself. A tree, he explains, that was one of the first back our Isles at the retreat of the last ice age around 10,000 years ago. It occurs all around the northern hemisphere from the tree-line in the arctic to dry regions of the Mediterranean.

Another excellent experience see Trevor show Chris, and us, how Juniper foliage succeeds at -6 degrees centigrade where a dogwood leaf fails. Using a thermal camera, we see the dogwood leaf turn black very quickly as the water turns to ice. The ice then expands and irreparably damages the cells within the dogwood leaf by punching through the cell walls with their sharp points– even though to the naked eye, the leaf still looks fine. The juniper leaf, however, has inbuilt protection in the form of antifreeze. Naturally occurring antifreeze is common for plants and animals in cold regions, such as the arctic and Antarctic. Unfortunately, due to grazing by the sheep that live up the mountain, the juniper is becoming very scarce.

Trevor explains that all of the junipers have been mapped and farmers can now receive grants to remove sheep from these areas. Sadly, although making the issue crystal clear, Trevor searches for a mapped juniper only to find that it is dead. With the sheep eating the seedlings, there are no replacements when the old trees die. As the distance between junipers increases, the chance of reproduction lowers. Chris is very sensible when he comments that it is difficult to find the balance between the plants that grow in an area and the animals that need to graze there .

The situation is so serious, not just at Snowdon but nationwide, that the charity Plantlife has created a publication for the management of uplands for juniper. It’s available here.

Another great episode and it’s dealing with increasingly important issues in the plant world. These topics are so important, but until now haven’t received mainstream airing – or if it has, I haven’t seen it, possibly making the point.