Floresta Portuguesa Sustentável – Sustainable Forests for Portugal

September 16th, 2012. Post by Quinta do Vale

In the wake of the large increase in the number of forest fires in this area this summer – the latest last night around Barril de Alva – a group of us, both foreign and Portuguese, started up a Facebook page and group to discuss how we might go about encouraging landowners to move away from the highly flammable eucalyptus and Maritime pine plantations and start planting a mixed, biodiverse forest based around indigenous species rather than these hugely destructive and unsustainable cash crops.

Eucalyptus flower on forest floor

Clearly it’s an issue close to many people’s hearts. Just short of 1,000 people joined the group within the first 48 hours of its formation. Facebook isn’t the easiest platform to discuss these issues, but it’s a start. Check out the page for links to many online resources on the subject and the group for discussions about the initiative. A website and forum is forthcoming. I’ll add links to those as they come online.

If this issue touches you at all, please join us and help make a change for the better.

It’s not just a matter of the fire hazard either. Eucalyptus plantations are an environmental disaster. It’s a fast growing tree, which is why it’s a popular choice as a cash crop, but it thrives at enormous expense to Portuguese water and soil resources. According to research from the Kenya-based International Centre for Research in Agroforestry (ICRAF), a single 3-year old eucalyptus consumes 20 litres of water per day. By age 20 the tree will consume 200 litres per day. This means that one 3 year-old tree will consume 7,300 litres of water per year. One hectare of 3 year-old trees planted at typical plantation density (1,100 trees/hectare) will consume 8,030,000 litres of water in a year. If the trees are allowed to grow until they’re 20 years old, that figure rises to 80 million litres of water per annum.

Now let’s put this in context. The average annual rainfall for Central Portugal is around 900-1200mm. For the sake of this example, I’ll take Viseu, which averages 1,170mm per annum and is one of the higher figures for the region. 1mm of rain falling on 1 square metre = 1 litre and there are 10,000 square metres in a hectare, so this rainfall equates to 11,700,000 litres of rainfall per annum. This means then, that over the average 10-year cycle of growth and harvest, a hectare of eucalyptus consumes around 4.5 million litres more water than the amount of rain falling on that land over that period. Taking the whole of the Central and Northern regions of Portugal, only 61% of the plantations’ water needs are met by the amount of rain that falls on them.

In actuality, this figure is even less since around 20% of plantation rainfall is likely to be lost to runoff. So less than 50% of the crop’s needs are being met by rainfall. This is not sustainable.

Approximately 740,000 hectares are currently devoted to eucalyptus cultivation in Portugal, around 8% of the total land area of the country. Taking into account the average rainfall over the whole country, this means that the total area planted to eucalyptus is consuming 14% of Portugal’s entire annual rainfall, rising to 17% if you allow for losses to runoff.

No wonder, then, that groundwater supplies are falling and failing in many areas, or that the climate is becoming drier, since aside from its prodigious consumption of water, this species does not have the rain-creating potential of a broadleaved forest. It’s really no exaggeration to say that if these plantations continue, Portugal is set to become an extension of the Sahara desert.

Further reading:

Área ardida mais do que triplicou (Burned area has more than tripled)
European Environment Agency: Nature protection and biodiversity (Portugal). Why should we care about this issue
What are the opinions of Portuguese foresters regarding fire? Results of a questionnaire
World Rainforest Movement. Kenya: the Forest Service to the rescue of eucalyptus
Quantification of Soil and Water Loss from Teak and Eucalypt Plantations

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