You want to know what impact climate change will have on landscapes? Come to the Centro Region of Portugal and take a look.
Having spent some months in the region, I really feel on the front line of climate change. I have blogged before about the devastating fires the area has suffered from (see here and here). These however are just the latest in a series of destructive impacts that go back a long way historically, which make the landscape of this area a particularly alarming example of what can happen over long periods of time, with contemporary climate change contributing a final blow.
One of the odd things that one notices around here is the areas of bare ground, not just solid rock but gritty bare 'soil'. Rainfall is pretty high here (at least September to April), so this apparent 'desertification' is a bit of a mystery. There are places where it seems entire hillsides are bare of vegetation. In other areas, such as around the village where Jo and I are currently living, the fires have revealed more bare soil beneath the blackened trees. Unpacking what has happened has taken some time.
Much of the region is granite, which produces gritty infertile soils. But the climate is mild and rainfall plentiful so human populations have always been high, with some areas having remarkably high densities of villages even in the pre-Roman period. Lots of people meant deforestation plus lots of grazing animals, so tree cover began to be lost from pretty early on, to be replaced by heather, gorse, broom and other low woody plants. Grass, the most thorough protective skin for soil, does not grow particularly well as the soil is simply lacking in sufficient phosphorus and nitrogen. Soil erosion, driven by heavy winter rains, gradually stripped hillsides of anything the grass could grow on anyway, dumping it in the valleys (which at least helped peasant cultivators). The remaining grit, almost entirely stripped of humus or finer soil particles can now only support thorny shrubs (mostly pea family) or annuals. This is the situation on much of the Serra da Estrela, the highest hills in the region: once high pastures, now looking like semi-desert.
Many overpopulated European landscapes were saved by the safety valve of emigration to the New World in the 19th and early 20th centuries. There was relatively little emigration here though, so the pressure of deforestation and grazing built up. By the mid 20th century, the government (the Salazar dictatorship) recognised the problem and began to promote reafforestation, but not with the original oak and chestnut, but quick growing pines, and then eucalyptus. As with so many other hilly places in western Europe, rural depopulation emptied the countryside. Here the climate made the industrial planting of eucalyptus an increasingly attractive investment both for the corporate sector and anyone with a few hectares who wanted a reliable pension fund. Given that the landholding system is such a mess (ownership of something around 20% of the countryside is disputed), 'guerrilla planting' of eucalyptus is rife.
Eucalyptus globulus is a tree which evolution has designed to burn ferociously, scattering red hot embers for kilometres downwind. Whereas strawberry trees (Arbutus unedo) resprout impressively from a burnt stump and cork oak (Quercus suber) from all over the branches, this particular eucalyptus sends out vast numbers of new shoots all the way up the trunk, and surrounds itself with its seedlings. The tree is able to generate a cycle of burning which eliminates pines, its main competitor, and over time would eliminate any remaining oaks or chestnut, which do not burn but grow much more slowly.
It was interesting to go to Tasmania in the spring and see Eucalyptus globulus in the wild. Australia's landscape history saw eucalypts gradually displace other slower-growing tree species as the Aborigines used fire as a landscape management tool; assisting the mass extinction process which tribal hunter-gatherers caused all over the world during the Stone Age. There the process took millennia to complete; in Portugal it is taking just a few decades to go much further and completely degrade the landscape. Wild eucalyptus in Tasmania grows quite sparsely, in multi-age stands; in Portugal, even-aged plantations pack the trees in as densely as possible, so the amount of highly inflammable biomass is concentrated far more than would ever happen naturally.
'Desertification' is not an exaggeration to describe what is happening. The firestorm of last October, the worst landscape fire globally in 2017, was a qualitatively new experience for Europe, an event which was almost certainly climate change induced and which is now far more likely. Although fed by eucalyptus, I could imagine conifers feeding a similar event in the right set of circumstances (high wind velocity after a long drought). What has happened to this region should be a warning for other places.
This is of course the era of conspiracy theories and fake news, and so of course a variety of paranoid fantasies have unfortunately taken hold, which do nothing to help target the blame where it belongs: the corporations who produce chipboard and paper pulp from the eucalyptus and promote its growth and the ineffective government. There is a group called 'Ceus Limpos' (clean skies) which is propagating the daft idea that drones and planes spread the fire deliberately. As if the region does not have enough problems already!
One further impact is a psychological one. We have lived for several months this year in a devastated landscape. It quickly becomes the 'new normal'. Local residents still talk about good walks in beautiful places as if they are still there. After being here a while it is almost a shock to go somewhere undamaged, even to take a walk in an ordinary pine forest with a bit of heather on the ground seems so refreshing.
A way forward? Really only the replanting of native oaks and chestnuts, from the evidence around us, it would seem that decent stretches of these trees would be very effective as fire breaks, and would do more to build up the soil than plantation eucalyptus. There are some organisations working around this. https://criarbosques.wordpress.com/ Paulownia is being touted as an alternative to eucalyptus for smallholder plantations; though an invasive itself in some parts of the world, it is at least deciduous and doesn't burn too badly. Ultimately though this is a political problem, to break the stranglehold of the pulp and chipboard industry over the government, an industry it is worth pointing out, that brings in a declining proportion of national income compared to pretty well every other timber producing country in Europe.
If you read Portuguese the following are useful sources:
Paleo história e história antiga das florestas de Portugal Continental − Até à Idade Média Carlos Aguiar e Bruno Pinto. Available here.
Portugal em Chamas - Como Resgatar as Florestas, João Camargo, Paulo Pimenta de Castro, Pub: Bertrand.
And even if you don't read the language, this is a good and powerful photo-essay, more about the human impact, and at the end a very good map that gives you an idea of the scale of the disaster of last October.