The ‘botanical melting pot’ of Madeira: Notes on natural history and ecological restoration at species, ecosystem, and landscape scales

By James Aronson and Thibaud Aronson. All photos by Thibaud Aronson.

Perhaps best known for the fortified wines that bear its name, Madeira is in fact a small archipelago in the Atlantic Ocean, some 500 kilometers (310 miles) from the shores of Morocco and about twice that distance from Lisbon. Volcanic in origin, these islands, together with the Canary Islands and the Azores, form a distinct biogeographical region, known as Macaronesia. (The islands of Cape Verde are sometimes also included in that group, but they are much farther to the south, and truly belong to the Afro-tropical realm.) Politically, the Madeira and Azores archipelagos belong to Portugal.

The main island of Madeira is just 740.7 km2 (286 mi2), while the handful of others are rather barren, and mostly uninhabited. That means the entire Madeiran archipelago is about the size of a medium-sized National Park in the US, such as Crater Lake, in Oregon, for a total population of just over 250,000.

For garden and natural history/cultural history-oriented travellers, Madeira and its neighbors – the cooler Azores to the north, and the drier Canary Islands – are spectacular: these are three of the most appealing areas of the Atlantic for human habitation, gardening, farming, and hiking, with floras and faunas related to European, Mediterranean, and African biota, as well as some unifying Macaronesian elements shared among the three archipelagos. Agricultural crops are also quite spectacularly varied, with a strong presence of vineyards of very stunning appearance, and also subtropical bananas (about which, for some history, including the tale of the EU’s “bendy banana law”, see here).

Traditional vineyards with heritage grape varieties on the slopes of Câmara de Lobos, west of the capital. Numerous banana fields share this valley and many others like it in the periurban area around the capital city of Funchal.

Of particular interest on the island – of combined natural and cultural heritage value, are the laurel forests (laurisilva to botanists). Mostly dominated by evergreen trees and tall shrubs of medium stature – no more than 15-20 m high – these kinds of forests typically occur at subtropical latitudes, in areas with mild climate and high humidity. They can be seen – in unconnected fragments for the most part, and with varying botanical composition of course – in places such as the Himalayan foothills, central Chile, or the highlands of Ethiopia. In Europe, true laurel forests used to cover much of the Mediterranean basin during the Tertiary era, from which they receded and disappeared as the region’s climate got progressively drier. Apart from a few fragments left in the remote Anti-Atlas Mountains of Morocco, and one small patch in southern Spain, the only surviving Atlantic laurel forests are found in Macaronesia. The highlands of Madeira hold the largest and best-preserved stands, somewhat protected over the past six centuries by the island’s dramatic topography and, since 2009, thanks to recognition as a UNESCO World Heritage site covering 15,000 hectares.

Madeira’s laurisilva is draped in mist more often than not, and exuberant lichens and ferns cling to every tree branch, giving these forests a very primeval feeling, unlike anything else in Europe. The forest type is dominated by under a dozen evergreen tree species, most notably laurels (5 species in 4 different genera of Lauraceae) and tree heaths (Erica spp.), some of which get to be exceptionally tall for Ericas. But there are several dozen endemic shrubs and herbs in the undergrowth, such as various Geraniums and several giant daisy relatives. It has three endemic bird species as well.

The whistles of the Madeiran Firecrest (Regulus madeirensis) are one of the most common sounds of the laurisilva, as this tiny sprite of a bird flits from branch to branch.
The shy Trocaz Pigeon (Columba trocaz) is endemic to the forests of Madeira. Its two closest relatives are also laurisilva specialists, found in the western Canary Islands.
The Madeiran Chaffinch (Fringilla coelebs maderensis) is most abundant along the levada canals of the Madeiran highlands, where these fearless birds have become accustomed to being fed crumbs by hikers.

The archipelago was uninhabited until Portuguese sailors claimed it for the Portuguese crown in 1417. The island’s appealing climate was not lost on them and they set about settling it. Much of what they did shaped the island that we know today and no doubt led to a massive amount of irreversible clearing, deforestation, and soil erosion, as we will discuss further on.

Madeira’s climate is very unbalanced. The northern slopes can receive nearly 3000 mm of rain in a year, while the southern part of the island is much, much drier. However, the south has gentler slopes, making it much more suitable for building and agriculture. Therefore, the Portuguese set about building levadas, irrigation canals to bring water from the north to the south. This enormous network, spanning thousands of kilometers, much of it dug from sheer cliff faces, with numerous long tunnels as well, was built over four centuries (with slave labor, many of whom lost their lives in the process); without it, large-scale settlement of Madeira would have been near impossible.

A narrow path along the levada of the Caldeirão Verde (Green Cauldron), in the island’s central highlands.
Waterfalls are plentiful along the sheer slopes of the highlands.

The island also achieved tremendous prosperity especially in the 17th, 18th and 19th centuries, thanks to its privileged position for maritime trade in the north Atlantic and, for a while, its role as one of the world’s largest sugar cane exporters. The richer inhabitants, taking advantage of the favorable weather, began a tradition of having extravagant gardens, with plants from all over the world. Indeed, a walk in the streets of any town on the island today will reveal gardens bursting with an incredible melting-pot of plants, with Hydrangeas (from east Asia), growing side by side with Agaves and Yuccas (from Mexico), Agapanthus (from South Africa), Brugmansias and Passionflowers (from the Andes), Bougainvillea from the South Pacific, and more marvels, all under the shade of massive Agathis and Eucalpyts (Australia) and Araucaria trees (Norfolk Island, and Chile)! There is perhaps no better illustration of this potpourri quality of the cultivated plants than the fact that Madeira’s official flower is the Bird of paradise, Strelitzia reginae, a native of… South Africa!

However, to anyone with naturalist’s eyes, a lot of what is seen outside of gardens is quite worrisome when one considers the island’s native flora, fauna, and varied ecosystems outside of the protected areas where the laurisilva occurs. There are massive areas of soil erosion, and as elsewhere throughout the Mediterranean region, abandoned lands and pastures that appear to have been cleared and then repeatedly burned over several centuries to maintain grazing lands for sheep and goats. Most of the extant revegetation has been done with Eucalyptus globulus, Mediterranean pines, and various other non-native conifers and  Australian Acacias. Of these latter fast-growing, colonizing, bird-dispersed trees, at least 6 are invasive on Madeira and the Azores, the worst of the lot being Australian blackwood.

Most slopes on the southern face of the island are completely overtaken by Australian blackwood (Acacia melanoxylon) invasion, as seen here just above Funchal, the capital.

So what now, from a restoration ecology perspective? Madeira is subject to strict Portuguese laws regarding sale or import of known invasive plant species; this makes a lot of sense given that already 15% or more of the flora of Portugal, and probably more than that in the Azores and Madeira consists of non-native invasives. But a lot of work beyond protection against new invasions could be envisioned, starting with control or eradication efforts on such an island whose natural beauty and biodiversity are its greatest asset. Reintroduction and reinforcement of populations of endangered native species are also needed and initial experiments in ecosystem restoration could be undertaken on the main island and perhaps some of the smaller islands as well. Education and job training and greater funding for restoration work are all needed and would probably be of great, and lasting value to local communities and the Autonomous Region as a whole. Coordination with similar efforts in the Azores, and on the mainland territory of Portugal should all be encouraged.

One invader to be carefully monitored on Madeira is Kahili Wild Ginger (Hedychium gardnerianum) a garden-escape that is known to do great ecological damage to native woodlands in Hawai’i, and elsewhere. The IUCN considers it to be one of the world’s 100 worst invasive species. Indeed, its 1.5 to 2 m tall stalks can form extensive stands, with dense mats of rhizomes, that can choke out native understory if left unchecked. Reportedly, control efforts are underway inside the Madeira Natural Park.

But what about all the areas infested with woody weeds outside the parks and UNESCO Heritage sites in the mountains? From our point of view, the extensive and multiplying stands of Acacia melanoxylon and other invasive wattles (Australian acacias), of Gorse (Ulex europaeus) and a few other noxious woody weeds we saw plenty of,  it seems clear that manual and mechanical controls, and perhaps some biocontrol would be worth testing.

And, what about everything that ecological restoration, sensu lato, could bring to Madeira? On one road, in the center of the country, we saw a rather large plantation of tree saplings that looked like Ocotea foetens, one of the five native laurels of the laurisilva. That was encouraging to see, but the trees were planted grid-fashion and in monoculture, so that it was unclear what the intention was. As readers of this blog well know, reintroduction (or reinforcement of populations) of a single species of native plant or animal is not the same thing as ecological restoration: ‘restoration of Ocotea foetens’ is a non sequitur whereas reintroduction of this native tree, or its use in reforestation does make sense.

We also learned that studies are underway regarding the native olive tree, long considered a feral ecotype or, for some systematists, a subspecies of the widespread European olive, Olea europaea, but now generally accepted as an island endemic Olea madeirensis. Pride in such native species should be definitely encouraged, serving as a driver for more attention to what should be planted in the context of future ecological restoration programs in coastal areas and hills, and in environmental education programs, parks, and botanical gardens as well.

Next, let’s consider the spectacular Dracaena draco, or Dragon tree, that prospered on Madeira and also in the Canary Islands, Morocco, and Cape Verde, until Europeans in the 15th and 16th century began aggressive tapping of the sap from this stem succulent tree – the so-called Dragon’s blood – which was widely prized as a durable natural dye. By the end of the 16th century, Dragon tree was rendered nearly extinct in its natural distribution area thanks to a typical boom and bust pattern of exploitation, and today, the only wild populations of any importance occur on Tenerife, in the Canary Islands, with a few individuals in Morocco and Cape Verde.

This iconic tree is seen planted all over Madeira, and indeed in frost-free dryland gardens all over the world. But there probably isn’t a single wild dragon tree left on the island! So, what should attempts to restore an ecosystem with populations of Dragon tree look like, over and beyond reintroductions? What reference should be used and which provenances of what trees should be planted and what else is needed for the project to survive and be meaningful to Madeirans?

Rather spotty plantation of Dracaena draco along with the showy but non-native and potentially invasive Aloe arborescens near the village of Caniçal, on the easternmost peninsula of Madeira.
A centuries-old specimen Dragon tree in one of the surviving stands of native Dracaeno draco on Tenerife, (near El Draguillo), Canary Islands.

And now, for our last snapshot, let’s consider the Foxtail Agave, that is widely planted and clearly spreading on coastal cliffs and hills in Madeira. It is an absolutely stunning plant, and of great natural history interest but it starting to naturalize, following in the pattern of Agave americana and Opuntia stricta, that could already be considered serious weeds. Local people probably don’t consider that a problem, and we can certainly understand that, given the newcomer’s graceful beauty. But like the Kahili ginger, and the widely planted Aloe arborescens, the Foxtail Agave is a serious pest on O’ahu and other Hawai’ian islands, and this should give cause for concern to Madeirans.

Fox-tail Agave, Agave attenuata naturalized near Câmara de Lobos.

But, then, who are we to say what attitude Madeirans and their authorities should adopt towards non-native invasives? Given the fact that tourism is now far and away the leading economic sector on the island, perhaps – like the Galapagos Islands, or Iceland, or Malta – greater sensitivity to the need for and the value of ecological restoration efforts will develop in the future.

One thing we could offer is a reminder that ecological restoration clearly includes restoration (or ecological and economic rehabilitation) of cultural or semi-cultural ecosystems, not to mention social-ecological systems and cultural landscapes. In the case of Madeira, this line of thinking would allow for reflection, and encourage investment in the restoration and rehabilitation of the working landscapes that thrived in lower latitudes on the southern half of the island with irrigation water being provided from the levada networks in the mountains. We can imagine remarkably interesting and inspiring landscape-scale restoration with ample opportunities for agritourism, and an expanded form of nature-based or ecotourism that would include cultural landscapes and heritage crops and traditional livelihoods, developed along corridors and valleys connecting levada canals all the way down to restored ‘working landscapes’ that certainly could have multiple benefits for local communities, for biodiversity, and for an emerging restoration economy linked to tourism. Worth considering, no?

 

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