Birch

As an addition to what is set out in various places in this work on the forest cover of Madeira, and in particular on the afforestation of the neighbouring island of Porto Santo (III-120), we transcribe some passages from an article by the illustrious botanist Carlos de Meneses, published in the former Diário do Comercio, which is of particular interest on this much-debated and ever-pressing subject.

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In 1910 a number of birch specimens were sent to Porto Santo to be planted there. They had been donated by a foreigner who takes a keen interest in the reafforestation of that island.

In the view of the experts, Porto Santo should be afforested with Madeiran or Mediterranean species, and never with species from central or northern Europe. These have climatic requirements that the island cannot satisfy, both because of its geographical position and because of the low altitude of its hills.

Even among the Madeiran species, it seems to us that choices must be made. It is not credible that the extremely dry and low-lying ground of Porto Santo would suit certain species that here in Madeira thrive only in the valleys and ravines of the interior, or else in the high, damp places on the southern and northern slopes of our island.

Madeira mahogany (vinhático, Persea indica), for example, is a species unsuited to the forest cover of Porto Santo. Although the specimens introduced there look healthy for the time being, thanks to the irrigation they have received, the time will come when they will wither and finally die, because they do not find in the soil and the atmosphere the conditions necessary for their existence.

Lack of rain and intense heat, with winter averages that are not very low, give the neighbouring island its climatic character. On its hills only certain species found in the lower zone of Madeira can be grown with advantage, such as the laurel, the til (Ocotea foetens, Madeiran laurel) and the barbusano (Apollonias barbujana, a laurel-forest tree). The Madeira mahogany (vinhático, Persea indica) is not among them, since it begins to appear with some frequency only above 400 or 500 metres and needs moisture to develop.

Now, if the Madeira mahogany, a Madeiran species, is unsuitable for afforesting Porto Santo, the birch is even more so. As is well known, this tree reaches its southern limit in the Alto Minho, Gerês, Marão and the Serra da Estrela, and forms significant stands only in the northern regions and in central Europe, where the cold is extremely intense in winter and the warm season is short.

Even if the birch were a Mediterranean species suited to cultivation on Porto Santo, we would still exclude it from the island’s forest cover, because trees with deciduous foliage are not very suitable for afforesting countries with hot climates.

What the neighbouring island needs is evergreen trees, as those of Madeira generally are, in order to protect the soil from evaporation as far as possible and so encourage springs to appear. A cover made up of deciduous species would do little to improve the condition of the land, since the influence of such a cover must necessarily be very limited in a country with winter averages that are not very low, such as the one of which we are speaking.’