This is the view from the top of the track down to the larger building on the quinta. In many ways it encapsulates the nature of the “Green Heart of Portugal” – forested mountain ranges cut deep by meandering river valleys, peppered with tiny white villages perched on mountain ridges, surrounded by land terraced and richly cultivated with olives, vines, fruit trees, vegetables … Idyllic.
But it encapsulates something else about the Green Heart of Portugal too – an ecological disaster-in-the-making presently taking hold in Portugal’s forests. The tree on the left is dying.
Pinewood nematode, pine wilt nematode, pine wilt, pine wilt disease … all names given to the disease affecting rapidly growing numbers of the Maritime pines (Pinus pinaster) which form the vast bulk of Portugal’s forests. It’s caused by the nematode Bursaphelenchus xylophilus, a tiny worm that infests the sap wood of various species of pine, and is vectored through various wood-boring insects, depending on where it’s present. Native to
North America Japan and Asia (see comments below), it has spread to the USA, Australia and Portugal, presumably via imported timber.
Not only does the nematode kill the trees it infects, it also renders the timber unusable. If left standing for more than a few months, the wood of the now-dead tree undergoes a change in structure and turns into a strange spongy substance that, aside from being useless for building, clogs the chainsaw blades that try to fell it and barely even burns, generating almost no heat.
When I first came here just 3 years ago, there was scarcely any evidence of it. People were talking about it appearing around Arganil, 20km away, but there was no obvious evidence of it in this valley. Now, this is the view across the valley.
The photo at the beginning of this post was taken last year, when we removed 3 trees with the disease on the quinta. This year we are going to have to take out more – I’ve counted around 10 and that’s before a thorough exploration of our bit of pine forest. Next year there will probably be more still …
So we’re bringing forward our plans for the woods and stepping things up a gear. The aim is to try and spot the infected trees at the first sign of infection and fell them before the wood becomes useless for firewood, burning them as soon as they’re dry, and stockpiling healthier trees for future years’ firewood, making clearings where we can start to plant more hardwoods. In doing so, we hope to steal a march on the disease. Lowering density and increasing diversity may offer some protection to remaining healthy trees, but even if it doesn’t, by the time the disease decimates the surrounding forest, we will hopefully have a well-established start to a new, more diverse and healthy forest.
My hopes are that it can also turn out to be a successful example of an alternative approach to the disease. Rather than clear-felling and replanting with eucalypts (
now against the law, but flouted with virtual impunity see comments below) which will cause even more environmental damage and increase fire risk, I hope to show that it’s possible to regenerate a largely indigenous but also productive, valuable, non-flammable forest from which high-value timber such as chestnut can be harvested regularly through coppicing and provide a good return in less time than it would have taken to bring pine forest to maturity and harvest. Although we won’t be harvesting our trees in this way, for local people it’s part of their livelihood and how they look on their forest. If they’re to turn away from present practices, then there needs to be a reason and viable incentive to do so.