Fundación General CSIC

Lychnos

Notebooks of the Fundación General CSIC <span>Digital Edition</span>


Go back to Articles

   Print

On Biodiversity...

JORGE CASSINELLO ROLDáN

Instituto de Investigación en Recursos Cinegéticos (IREC, CSIC-UCLM-JCCM)

The Mediterranean’s mosaic landscape and its survival: from pastoralism to the role of exotic species

The Mediterranean’s characteristic plant community is under threat from human activities, which have altered its composition and structure, reducing its wealth of species, and, in short, degrading its nature.

Share |
Ecosystem-wide threats
Whenever threatened species are mentioned, examples from Spain’s fauna such as the Iberian lynx, imperial eagle, or monk seal rapidly come to mind. At the global level we might think of the blue whale, Bengal tiger or giant panda. These species are conservation icons, and often serve as a “flagship HIGHLIGHTSProfile: Jorge Cassinello Roldán
species” to draw attention to the conservation of the ecosystems they inhabit. The positive effect of using these attention-grabbing species is well known. Species that the collective imagination finds attractive, acceptable and lovable can bring public opinion around to supporting nature conservation policies. But these examples are just a tiny part of the tip of a huge iceberg. According to the International Union for Conservation of Nature (IUCN) Red List, in 2011 there were 19,570 threatened species. This estimate is based solely on those taxonomic groups that have been sufficiently assessed, so the real figure could be much higher.

No species lives in isolation. They are always part of an ecosystem in which they find their home or ecological niche. This could be described as the set of abiotic (physical) factors and biotic factors (organisms) that determine the optimal conditions for all stages of their life cycle. Species therefore live in the company of many other animals and plants. Their relationship to some will be close, for ex­ample if they are a food source, potential predator, or simply fellow travellers, perhaps competing for resources. It is clear that the warning that the IUCN admirably sums up in its Red List, caused to a large extent by the direct and indirect human action, is not limited to specific species, except where they are the specific object of interest and are the target of efforts to hunt or capture them directly. Instead, in most instances the threat affects a particular habitat or ecosystem. Consequently, it can be said that some ecosystems are threatened by human action, through the alteration of their composition and structure, reducing the wealth of species comprising them, and in short, degrading their nature. This is currently the case of the plant community characteristic of the Mediterranean region. Let’s look at why.




The Barbary sheep or arui is a grazing species that might be suited to occupying an empty niche in the Mediterranean environment. / Photo courtesy of the author.


The Mediterranean basin: an example of biodiversity
The Mediterranean basin is considered a conservation hot spot on account of the wide diversity of biological forms it is home to. Its 2.3 million square kilometres are home to at least 25,000 plant species, corresponding to 10% of the earth’s total, occupying 1.6% of the planet’s land surface. Moreover, approximately half these species are endemic to the Mediterranean, and 12% are rare or According to the IUCN Red List there were 19,570 threatened species in 2011threatened. And this percentage is on an upward trend. What has given rise to this fantastic biodiversity? There are four factors to be taken into account: its biogeography, geology, ecology and history. After the last glaciation, the so-called Würm glacial stage, which peaked around 20,000 years ago and collapsed dramatically around 10,000 years ago, a period of change began in the Mediterranean basin, in which the new and previously unknown behaviour of the human species played a role: resource collection. This period is the Neolithic, when our species started out as a hunter-gatherer, and gradually began farming and herding. This is was when the domestication of plants and animals began. The availability of animal and vegetable foods, without the need for nomadic movements due to the seasonal changes affecting resource availability led to the creation of stable human settlements. This meant the advent of villages and towns, and trade. A major transformation took place that gave rise to our civilisation and, progressively, a no less drastic transformation in the natural environment we live in. The Mediterranean basin has therefore witnessed these major changes and their consequences.


The changes during the Neolithic
At the start of the Neolithic the geographical environment was characterised by a broad diversity of plant ecosystems which had co-evolved with a wide variety of herbivorous animals.

These included various types of deer, particularly browsers (such as Cervus spp. or Dama spp.), i.e. animals which feed on all types of woody substrate, and large bovids such as the aurochs (Bos primigenius) and European bison (Bison bonasus), which are essentially grazing animals, like the Eurasian wild horse or tarpan (Equus ferus). The fossil record shows these ungulate herbivores to have been abundant as a group throughout the basin, resulting in a high level of grazing pressure on the plant cover. This led to plant species in the Mediterranean developing physical and chemical defences, through a process of co-evolution between plants and herbivores. Moreover, the high degree of diversity among both woody and herbaceous Mediterranean plants was favoured by grazing, as it controlled the proliferation of dominant species in the plant community.




A significant increase in the native population of ungulates is taking place across the European continent. / Photo courtesy of the author.


However, the balance between plants and herbivores began to be altered by human activities in two complementary areas: hunting, and domestication of wild species. Hunting led to an unprecedented, and excessive, pressure on the ungulates, particularly the bison and aurochs. In the case of the bison, once abundant on more northerly prairies and woodlands, hunting for its meat and skin led to a progressive disappearance of the Species from the Mediterranean basin. Thus, the last recorded bison on the Iberian Peninsula lived in Navarre in the 12th century. In the case of the aurochs, The Mediterranean basin is considered a hot-spot in terms of conservationit is believed that the factors leading to their extinction were hunting and degradation of their environment by man, together with the likely competition for resources with domesticated cattle populations. The most recent genetic studies seem to indicate that domestication of the aurochs only took place among populations in the Middle East, but that this domesticated version spread rapidly throughout the mediterranean. The aurochs seems to have become extinct in the Mediterranean basin in the later years of the Roman Empire. In the case of the tarpan, its progressive disappearance in the Neolithic seems to be mainly the result of its being displaced by the growing population of domesticated horses in the region. In short, the gradual process of domestication of wild species by man in the Neolithic is considered to be one of the most important factors in explaining the extinction of grazing herbi­vores such as the aurochs and the tarpan.

By the same token, the changes in the habitat in the wake of the spread of farming must have also had an important role in displacing ungulate populations, particularly those living in valleys and mountainous areas. What is more, the gregarious behaviour of the large grazing herbivores may have worked against them. Bison, aurochs and tarpans showed a high trophic dependence on rich grazing land, which varied with the seasons. This fact probably caused migratory movements of large herds of these animals as they looked for the best pasture, as other species of ungulates do today. This characteristic would undoubtedly have made them easier for Neolithic man to track, hunt and capture.




Various factors are encouraging a shift away from both arable and extensive livestock farming right across the Mediterranean. / Photo courtesy of the author.


The fact is that during this crucial period in the Mediterranean basin, from around 10,000 years ago to approximately 3,000 years ago, man altered the landscape, hunted species to extinction, domesticated plants and animals, and created a new order, which, paradoxically, was characterised by a wealth of flowers, and in which woods, scrubland and pasture alternated. To some extent, the niche occupied by the extinct grazing ungulates came to be occupied by cattle, horses, sheep and goats, which together placed a high degree of grazing pressure on the land, perhaps similar to that of the preceding wild ungulates.


Current changes: environmental consequences of the rural exodus
What is happening today? The socio-economic reality of our society is causing a progressive and at times rapid abandonment of the rural environment. The shortage of economic resources, the better opportunities the cities offer, and in short, the rural population’s perception of a complete lack of a stable future is encouraging people to give up both arable farming and stock rearing across large swathes of the Mediterranean basin. This fact is leading to a marked advance by scrub and even woodland in areas where a mosaic pattern once predominated, alternating with pasture and meadows. The consequences are as yet hard to predict.

The main negative impacts this situation is having include:

  • Homogenisation of the plant ecosystem. Loss of biodiversity.
  • In arid and semiarid climates, increased erosion due to the loss of plant cover.
  • The loss of the heterogeneity of habitats will affect animal species adapted to the ecotone and variable structure habitats.
  • Increased risk of forest fire due to the increase in scrub and biomass fuel.

It is clear that the role played by extensive stock farming, occupying an ecological niche that had once been the domain of large grazing herbivores, has allowed the mosaic landscape typical to the Mediterranean basin to be maintained. This is a landscape in which there is an alternation of pasture, scrub and a wide variety of types of woodland, depending on the altitude, soil composition and other bio-geographical factors.


Wild ungulates
A significant increase in the native population of ungulates is currently taking place across the European contin­ent, and in the Mediterra­nean basin in particular. The reasons are varied, but their interest to hunters, the lack of natural predators, and the abandonment of the rural environment by man are among the principal causes. This increase in herbivore numbers is occurring with a significant bias, such that browsing species basically predominate. The main species in the Spanish Mediterranean scrublands are the red deer (Cervus elaphus), roe deer (Capreolus capreolus) and fallow deer (Dama dama), and in the higher mountains, the Iberian ibex (Capra pyrenaica); the case of the chamois (Rupicapra pyrenaica), a generalist with browsing and grazing habitats, is different, as it is highly localised to mountainous areas of Cantabria and the Pyrenees. There is, therefore, The domestication of wild species by man in the Neolithic was a decisive factor in the extinction of the grazing herbivoresa clear shortage of grazing herbivore ungulates in the autoctonous fauna of the Mediterranean, as the aurochs, bison and tarpans became extinct centuries ago, as we have seen. Moreover, we have also seen the ecological niche left by these extinct species gradually filled by cattle, sheep and horses. Until now, that is.

In this situation, is the mosaic plant ecosystem that has characterised the Mediterranean since the start of the present postglacial period in danger? Perhaps not. It is not entirely true to say that we lack wild ungulates that feed primarily on herbaceous plants. The thing is that these ungulates are not autochthonous, or at least one of them is not. The species in question are the mouflon (Ovis orientalis musimon) and the Barbary sheep or arui (Ammotragus lervia).

The evidence suggests that the mouflon was a wild sheep, originally from Asia, that underwent the first stages of domestication in Europe in the early Neolithic, returning to the wild on various Mediterranean islands. The domestication of wild sheep probably began around 8,000 years ago in Eastern Europe, on the Anatolian peninsula, and the mouflon was an early ex­ample of this process. Its close genetic relationship with today’s domestic sheep suggests it is one of their ancestors. While on mainland Europe and in the Middle East populations of domestic sheep proliferated, on the Mediterranean islands of Corsica, Sardinia and Cyprus, mouflon populations remained intact. This singular animal has a dark brown coat, and the males have conspicuous white saddle markings. Later, in the 18th century, it started to be introduced onto the mainland from the islands as a game animal. Pastoralism has maintained the mosaic landscape typical of the Mediterranean basin unchangedThere is also evidence that it was introduced in Medieval times as an ornamental species in parks and gardens. Its increasing value as a hunting trophy have led to there being significant numbers of the animal in the wild in a number of countries in central and eastern Europe, and also in Spain. It was introduced in Spain in 1953, with the release of a few specimens from France and Luxembourg in the Sierra de Cazorla, Jaén. Since then they have proliferated in the wild and in private hunting reserves. The Spanish population is considered one of the most valuable for hunting purposes; however, there is no data on the degree of inbreeding and the genetic variability and viability of Spain’s populations needs to be studied. Recent compara­tive studies on food selection show that it is basically a grazing species, apparently overlapping little with the other autochthonous ungulate herbivores with which it coexists, such as the red deer. The mouflon is perfectly suited to Mediterranean woodlands and scrub, preferring ecotone areas, or areas of dense scrub woodland in which there are clearings with pasture. It can also be found in rocky craggy areas, generally at altitudes of 1,000 to 1,500 metres. It is a species which adapts readily to a variety of environments, although it prefers scrub and rocky areas. It has also adapted to high mountain environments in the Pyrenees and the Alps.




Spain’s mouflon population is considered one of the most valuable as a hunting resource / Photo courtesy of the author.


The Barbary sheep or arui is a primitive North African goat species that some authors consider to be the origin of the evolutionary chain leading to today’s wild goats and sheep. There is little information about its status and distribution in its countries of origin, but is generally in decline as a result of indiscriminate hunting and changes to its habitat. As a species, however, the arui is not threatened, as there are introduced populations in the United States, northern Mexico and south-east Spain which are reproducing extremely successfully. Like the mouflon –or even more so– the arui is basically a grazing species so might be suited to an empty niche in the Mediterranean environment. It lives in rocky areas where mountain pasture and mixed scrub predominate. However, it does not adapt to all environments, preferring arid or semi-arid areas, where the precipitation is relatively slight. The arui has not managed to adapt to any other European country where attempts have been made to introduce it (e.g. Germany or Italy). Studies in captivity show a surprising ability to withstand high levels of inbreeding. Lastly, the species is a good coloniser, generating a wide distribution with a high reproductive rate.


How can we avoid the Mediterranean’s varied landscape being lost?
Preserving the plant biodiversity of the Mediterranean basin has to be a conservation policy priority. What solutions can we propose?

To date, extensive stock farming has helped maintain the landscape’s ecological heterogeneity, but today’s socio-economic reality is making it difficult to envisage subsidy or support policies that enable this type of pastoralism to remain viable on a significant scale. The gradual abandonment of the rural We need to bring wild grazing species back into our countrysideenvironment looks irreversible, and we are facing a new scenario which will have important environmental impacts in the near term. We need to be ready to respond to this challenge.
We need to bring naturally wild grazing species back into the Spanish landscape, in the form of animals that are able to look after themselves and reproduce in the natural environment. We now have a significant presence of two exotic ungulates in the countryside, and we have to face the ecological, and moral, question of whether, paradoxically, these species might be a useful means of managing our natural environment. We are still short of scientific data with which to understand the ecological impacts of these bovids on their new habitat, but it is possible to put forward some working hypotheses.

As mentioned, the mouflon is probably the ancestor of all the species of domestic European sheep, which are widely kept by shepherds right across the Mediterranean basin. They are less gregarious than flocks of domesticated sheep, and their likely damage to flora is not likely to be greater than that of their modern cousins. We could therefore consider the mouflon to be a native to the Mediterranean basin, in a broad sense, and perhaps a grazing species of interest to preserve mountain meadows and pastures.

The Barbary sheep is a bigger problem given its geographical and taxonomic origins. Detailed studies of its effects on the Mediterranean ecosystem would be needed to determine its environmental impact. Although its trophic ecology, feeding habits, and population dynamics are fairly well understood, if we manage its populations properly it might become an ally in preserving pastures and scrubland in Spain’s semi-arid mountain regions.

In short, as an ecologist I must give priority to scientifically based study, but I cannot rule out alternative hypotheses to the fundamentalist position regarding the “exotic” origins of the species. The quotes are mine.

To round off, please allow me one final liberty. What if we reintroduced the aurochs, the bison or the tarpan? Here we come up against a number of problems, ranging from the exoti­cism of species that have been absent from our ecosystems for centuries (debatable) to the viability of genetically “reconstructed” species (e.g. the aurochs, tarpan). The European bison is nevertheless a true survivor. The recovered population in Poland is a magnificent example of successful conservation, as it was on the verge of extinction in the early 20th century and has been saved by a successful captive breeding programme, although at the expense of a dramatic loss of genetic variability. There is a European programme to reintroduce the bison in several European countries, including Spain. I am not familiar with the details of the scientific basis or the ecological assumptions, but I do not rule out the possibility of progress along this path which could yield solutions helping maintain the landscape, particularly in more northerly areas. We need to be alert to events and advocate rigorous scientific monitoring.

In short, there may be solutions, but it is clear that we are witnessing a change in land use, and giving up the spontaneous sustainability created by Neolithic man. We need to carefully study the options and make big efforts to safeguard our rich natural heritage. Future generations will judge us; and I hope they will have reasons to do so benevolently.

Profile: Jorge Cassinello Roldán

Jorge Cassinello Roldán is a CSIC staff scientist and director of the Instituto de Investigación en Recursos Cinegéticos [Institute of Research into Hunting Resources] (IREC), a joint research institute belonging to the Spanish National Research Council (CSIC), the University of Castile-La Mancha and the Junta de Comunidades [regional government] of Castile-La Mancha. He has an honours degree in Biology from the University of Granada (1988). He completed his doctoral thesis at the Estación Experimental de Zonas Áridas [Arid Zones Experimental Station] (CSIC), Almeria, and was awarded a PhD in Biology from the University of Granada in 1994. For two years he held a contract as a Research Associate at the Sub-Department of Animal Behaviour, Department of Zoology, University of Cambridge, United Kingdom. He has also held postdoctoral contracts at the Museo Nacional de Ciencias Naturales [National Museum of Natural Science] (CSIC), in Madrid (1995-2003). In 2003 he obtained a Ramón y Cajal contract and joined the IREC, where he set up a research group that is currently focused on studying the behavioural ecology and conservation biology of ungulates. His lines of research include the study of parental care, reproduction, ecology and conservation of large herbivores, invasive exotic species, and their effects on the ecosystem, and the harmful effects of consanguinity. He has written some 70 publications, including scientific papers, science popularisation articles, and book chapters. He has supervised three doctoral theses, and has been responsible to date for 15 research grants, including projects, contracts and special actions, managing resources of over €600,000.

Published in No. 09


  • ® Fundación General CSIC.
    All rights reserved.
  • Lychnos. ISSN: 2171-6463 (Spanish print edition),
    2172-0207 (English print edition), 2174-5102 (online edition)
  • Privacy and legal notices
  • Contact

Like what we do? Keep up to date
with our latest
news and activities
on Facebook, Twitter or YouTube

Search options