Oliver Rackham, ovvero l'ecologia storica - #3
L'intervento di Oliver Rackham, in inglese ed inedito, alla prima edizione di MEDITERRE-Fiera dei Parchi del Mediterraneo che si svolse nell'ultima settimana di marzo 2003 a Bari.
The History of European Mediterranean Nature:
the Impact of Man
Oliver Rackham
Corpus Christi College, Cambridge, England
National Parks and the phantom of ‘wilderness’
National Parks originated in the nineteenth-century United States. Americans were obsessed with the idea of Wilderness: the belief that there existed parts of the world where ecosystems were unaffected by human activity. They thought their early National Parks, like Yellowstone, were examples of wilderness: they failed to understand the part played by American Indians in the development of such places. It was their policy to banish the local inhabitants and to try to forget that they had ever existed.
To some extent this attitude was transferred to Europe. As recently as 1962 the Samariá National Park was instituted in Crete. The inhabitants were expropriated, and visitors were invited to suppose that the Samariá Gorge was wilderness: to forget the illustrious part which it played in Greek history, and its archaeology which goes back to the Neolithic.[1]
Fortunately, in this Congress it seems to be fully understood that wilderness is an illusion. All the Mediterranean, including National Parks, is cultural landscape: the result of thousands of years of interactions between the environment (especially climate and mountain-building), plants, animals, and people. Even Palaeolithic people, who did not cultivate the soil, already had a profound ecological impact by exterminating elephants from the mainland.
The nature of human activities
Effects of people overlap with changes of climate, and it is difficult to separate them. When the first Neolithic farmers began to cultivate land and keep domestic animals the climate was wetter and less seasonal than now, so that the lime-tree, for example, was common in Crete. The Aridization, which gave rise to the present Mediterranean climate, took place gradually during the fifth to third millennium BC (later Neolithic and Bronze Age): it affected Italy less than Spain or Greece. Since then, there have been several fluctuations of climate, such as the phases of the Little Ice Age in historic times.
In most Mediterranean countries settlement and agriculture had advances and recessions through the Iron Age, Classical, and Hellenistic periods. From the Bronze Age onwards people built terraces, although most present terracing appears to be of the last 500 years. Often there was a peak of land-use during the Roman Empire, when rural populations reached roughly their modern level and landscapes were very fully used. People not only cultivated farmland but came to terms with the remaining natural vegetation and developed management by coppicing, pollarding, and periodic burning to produce a sustainable yield of produce.
To summarize human activities is almost impossible because (despite the prevailing theme of this meeting) Mediterranean countries are hugely variable. Even so small an area as the island of Crete is a miniature continent with its deserts and its jungles, its arctic and its tropics — a consequence of its violent tectonic history and towering mountains. Features like the badlands (landscapes composed of gullies) of Basilicata are not, as is often assumed, the ultimate result of ‘desertification’ produced by extreme human mismanagement: they are remarkable natural features resulting from a particular combination of tectonics and geology. (Badlands can occur in forest.)
Human activities are of five main kinds:
- Cultivation — which in theory destroys the previous natural vegetation, but in practice often leaves numerous remnants as hedges, on terrace walls, or on rock outcrops. Cultivation is also one of the factors that promote erosion.
- Replacing wild animals by domestic animals.
- Woodcutting (which should not be confused with deforestation, converting forest permanently into non-forest).
- Altering the natural frequency of fire.
- Introducing exotic plants and animals, which escape into the general landscape — such as Oxalis pes-capræ, probably the commonest wildflower around Bari, which came from South Africa.
Resilience of Mediterranean ecosystems
Mediterranean vegetation is not fragile. Browsing, burning, and woodcutting are all related to natural events, and Mediterranean vegetation is adapted to them. Mediterranean ecosystems are more resilient than some of the vegetation of similar ‘mediterraneoid’ climates in South Africa and Australia.
Browsing animals have their particular likes and dislikes. Goats prefer Quercus coccifera to cypress (Cupressus sempervirens ) , which explains the different behaviour of these two trees in the goat-browsed mountains of Crete.
Most Mediterranean trees sprout after being cut down and give rise to coppice stools: even some conifers, such as cypress, have this property. Mediterranean countries have extensive coppice-woods of evergreen or deciduous oaks, arbutus, hornbeam, chestnut, etc., from which crops of wood have been cut again and again and again over the centuries. Other trees, especially if widely spaced, are treated as pollards: successive crops of wood (or of leaves for feeding livestock) are cut , but at 3 m or more above ground so that browsing animals cannot reach the young shoots. Coppicing and pollarding prolong the life of a tree, and big ancient stools and pollards reveal the history of a site through centuries of woodcutting.
Fire is an adaptation, not a misfortune. Trees and plants mostly burn because they make flammable chemicals: it is their business in life to catch fire from time to time and burn up their less fire-adapted competitors. Fire-adaptation takes various forms. Quercus coccifera and arbutus are killed to the ground but sprout from the base. Some pines resist fire by their thick bark; others (such as Pinus halepensis) are killed but start again from seed. Many Mediterranean ecosystems are dependent on periodic burning, like those in the mediterraneoid climate of south-west Australia.
People and animals thus favour some species and disfavour others. Prickly-oak (Quercus coccifera ) is very resilient: it is palatable and moderately flammable, but sprouts from the base. It can exist in all forms from a shrublet a few cm high to a big oak-tree, and readily changes from one to another in response to different intensities and frequencies of browsing, burning, and woodcutting. Holm-oak (Q. ilex ) is less resistant to browsing, and in severely-browsed areas is confined to inaccessible cliffs.
The most desert-like parts of the Mediterranean today are not those areas with a history of peculiarly intense human exploitation, the environs of Athens or Rome or Florence or Seville. They are places with peculiarly inhospitable environments: extremely low rainfall (south-east Spain, south-east Crete), or hard unfissured limestone, or crumbly rock that breaks down into coarse fragments which do not retain moisture. They often have their own peculiar and beautiful plant life, the result of tens of thousands of years of adaptation to specialized conditions.
Forest, savanna, macchia
In Mediterranean countries trees do not necessarily grow in forests. There are the alternatives of coppice-woods, savanna (big trees widely spaced in grassland or heath), macchia (trees continuous, but reduced to the stature of shrubs), and trees stancing in fields and hedges. Savanna and macchia are partly due to human activities, and partly to natural factors, especially lack of moisture. They existed before the Aridization, and there are analogues of them in mediterraneoid parts of other continents.
The Neolithic introduction of agriculture and domestic animals was a less drastic and less conspicuous change than in northern Europe. It often amounted to converting a landscape of scattered trees and bushes into farmland with scattered trees and bushes.
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| Maestoso fragno (Q. trojana) isolato nel Parco Nazionale dell'Alta Murgia |
At present farming is in decline, especially on steep terrain, and forests are increasing. In many places, such as Liguria or the Balearics, cultivation terraces are now in forest. In Crete all the native trees, such as cypress and oaks but even the very rare Zelkova abelicea and the palm Phœnix theophrasti, are increasing. The island of Gávdhos (Gozzi) to the south of Crete, the southernmost place in Europe, which might be thought especially liable to desertification, has largely turned from cultivated land and pasture to pinewoods in the last 70 years. Even Mount Athos, the monastic territory in the north Ægean, which used to be held up as an example of a ‘virgin’ ecosystem unaffected by grazing animals, is a cultural landscape in decline: some of its most magnificent forests are on old terraces.
This is not necessarily a good thing. Withdrawing human activity does not re-create the ecosystem that existed before the activity began, nor the ecosystem that might now exist if the activity had never occurred.
Forests, especially recent forests, are not a good habitat for Mediterranean plants and animals, which dislike the combination of shade and drought. Of the many endemic plants of the Mediterranean — those limited to one region, mountain, or island — very few are forest species. Recent forests are often of pine, and therefore promote fire: this is part of the biology of pine. (Not content with the natural spread of pine, foresters insist on planting pines, sometimes of exotic species which are even more flammable than native pines.) Much of the recent increase in fires results from an increase in pine.
Savanna is very characteristic of semi-arid Mediterranean landscapes, but seems to be under-represented in National Parks, perhaps because ecologists are brought up to think of it as an artificial ecosystem unworthy of protection. However, savanna is a richer habitat for plants and animals than forest, especially if it contains ancient trees. It is partly determined by natural factors, especially drought: savanna occurs where there is enough moisture for single trees but not enough for forests. The savannas of the Mediterranean are linked to those of other continents — Africa, Australia, America — which often result from a similar combination of natural factors and human activities. All over the world, savannas are threatened by infilling which turns them into forest, to the detriment of their characteristic plants and animals.
Cultural landscapes and conservation
It is wrong to think of Mediterranean landscapes as ‘degraded’, as the sorry remnants of the noble forests and crystal fountains which supposedly existed in the golden age of the Classical or prehistoric past. On the contrary, human activities have been part of such ecosystems since before the Mediterranean climate arose. Even Mount Athos is not a sacred forest removed from the exploitation of the rest of the world. It is a peculiar cultural landscape, but cultural none the less: monks too needed food and wine and fuel and to earn a modest income.
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| Roccia calcarea affiorante - Parco Nazionale dell'Alta Murgia |
Land-use practices are an essential part of the habitat even of rare animals ane plants. Three examples of Cretan endemics illustrate this.
(1) Petromarula pinnata, one of the most beautiful of Cretan plants, which evolved long before Crete had human inhabitants. It is adapted to living on cliffs; but like many (but not all) Cretan cliff plants, it will grow on artificial as well as natural cliffs. It grows on walls, provided they are Venetian walls at least 400 years old.
(2) Verbascum spinosum, confined to a small part of Crete, where it is one of the commonest plants, and grows from sea-level to the tops of the highest mountains. Like many Cretan endemics it has an extraordinary array of defences against browsing animals: it not only has poison and distasteful fluff like other Verbascums, but is uniquely spiny as well. These devices now protect it against sheep and goats, but must go back to a much earlier period when Crete, like other islands, had its own peculiar herbivores including dwarf elephants and terrestrial hippopotami.
(3) Polygonum idæum, another browsing-resistant plant. It is one of a number of Cretan endemics which grow so close to the ground surface that sheep and goats cannot pick them up. It is the commonest plant on the floor of the Nidha Plain, high in the mountains, and occurs nowhere else in the world. Sheep and goats, replacing the lost elephants, now protect it against competition from taller plants.
Mediterranean cultural practices thus inherit and preserve species that originally had a different ecological function. Also, they have existed for so long that they have acquired their own peculiar ecosystems. Ancient trees, which are the specific habitat of many rare insects and lichens, are usually generated by cultural practices (wood-pasture, pollarding, growing olives and chestnuts). Threats to plants and animals arise from declining human activity as much as from expanding or intensifying activity.
Anyone wanting to preserve biodiversity should uphold old-fashioned land-use practices and their infrastructure. Do not marginalize local people: listen to them and learn from them before you start telling them what to do.
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[1] As recently investigated by the Sphakiá Archaeological Survey.
