Observing Agri-Forestry in Southern Spain

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OBSERVATIONS ARISING FROM A VISIT TO AN AGROSILVOPASTORAL SYSTEM IN SOUTHERN SPAIN.

This document is intended to disseminate information gained through a course based at from 19th – 26th April 2022. The course was developed by ARCH, funded through the Erasmus+ programme and hosted by Ernestine Lüdeke from Fundación Monte Mediterráneo.

Andy Dowse. May 2022.

Click to play serin song

 

Introduction.

From the 19th until the 26th April 2022 I took part in a visit to a working farm in southern Spain, approximately 70 km north of Seville.

The farm, Dehesa San Francisco, is in the Huelva province of Andalucía, close to the village of Santa Olalla del Cala. The farm is owned by the Fundación Monte Mediterráneo (Mediterranean Mountain Foundation) and has been managed by Ernestine Lüdeke and her husband for approximately 30 years.

As part of an ongoing program of educational courses the Fundación hosts many groups of visitors from around Europe. Course attendees are housed in a re-built farm building (see cover photograph). The course I attended was focussed on the principal aspects of the agrosilvopastoral system, i.e. the ecology of the Dehesa, pig and sheep production and the harvesting of cork. To that end (and ignoring the chronology) we were given a talk on the natural history of the Dehesa environment at the Oficina Parque Natural Sierra de Aracena y Picos de Aroche (The Office of the Aracena and Aroche Hills Natural Park). Later, we visited a ham curing business in Corteconcepción and a wool processing plant and lamb-finishing plant, both in Villanueva de la Serena. In Merida we went to the Instituto del Corcho, la Madera y el Carbón Vegetal (Institute of Cork, Wood and Charcoal) to learn about cork, it’s harvesting, properties and uses. Finally, in Seville, we were shown a community project aiming to improve the lives of people living in a deprived area of the city.

Click to play nightingale song

The Dehesa Environment.

Dehesa, pronounced de’esa, is a Spanish term used to denote a system of agriculture known as agrosilvopasturalism (or sometimes agroforestry). Oak trees provide wood, acorns and cork. Pigs, sheep, goats and cattle are grazed on pasture growing under the protection of the tree canopy, while the whole system maintains a high level of biodiversity, particularly when contrasted with monocultures of arable crops.

The dehesa landscape is dominated by species of oak tree (Quercus), principally holm oak, Quercus rotundifolia (previously classified as Quercus ilex, subspecies ballota) and cork oak, Quercus suber. The dehesa is an anthropogenic landscape produced as a consequence of clearing Mediterranean scrub-forest. This clearing has been occurring for millennia, but the management required to produce the dehesa of today was concentrated in the century 1750 – 1850 and again in the first 30 years of the 20th century (when the term dehesa was first used).

In Portugal this agroforestry system is known as montado. The Iberian Peninsula as a whole has 40,000 km2 given over to dehesa/montado. It generally occurs on shallow, sandy, poor quality soils and in areas that experience long, hot, dry summers. Given the soil and the climactic conditions these areas are not suitable for more intensive agriculture. Indeed, the tree cover – typically 10-100 trees/ha – helps to protect the soils and allows pasture to grow in the created shade. Despite this cover the grazing is much reduced, if not non-existent, by mid-summer, necessitating supplementary feeding or the wholesale moving of livestock. It also places a limit on the stocking density. In order to maintain a required amount of pasture it is necessary to clear the shrub layer every few years, encouraging grasses. While helping to maintain the dehesa system as a whole, this practise does negatively impact the biodiversity.

As well as providing shade and wind protection for the herbaceous vegetation layer (generally grasses), intercepting rainfall and preventing runoff, the oak trees also fulfil two other functions. In areas where Iberian pigs are raised for Iberico ham they are fattened up on the acorns dropped by the various oak species, producing a high-quality product. Secondly, the trees themselves can be harvested for wood, often through regular pruning, which may then be used as firewood, or processed to provide charcoal. The cork oak trees are periodically stripped of a portion of their bark which is used for various cork products, notably for stoppers in wine bottles.

As indicated, livestock for an integral part of the dehesa. Pigs roam and forage under the tree cover, taking acorns during the late autumn and through the winter. Merino sheep graze the pasture, often alongside cattle and goats.

Click to play pigs foraging (and nibbling my knee)

Iberico Pork.

The Iberian pig is the source of Iberico pork. Iberian pigs are a breed of the domestic pig, Sus scrofa domesticus. They are normally black (sometimes red), relatively hairless and are probably closer, genetically, to wild boar, Sus scrofa than are other domestic pig breeds.

After a period of time from the 1960’s onwards when the numbers of Iberian pigs were much reduced, principally a result of African swine fever, the population has been rising. A major reason for this increase in the Iberian pig population is an increase in demand for Iberico pork. There has been a recognition in the consumer market that Iberico pork is a very high-quality product; this recognition has an international reach, and is not restricted to only Spain and Portugal.

One of the places we visited was a curing plant in Corteconcepción, where Iberico pork is processed and made ready for sale. The major product was Iberico ham (see photo on left). Each ham is salted for a period of time relative to it’s weight, i.e. 1 month per kg. It is then washed and subsequently squeezed, to remove as much of the water as possible, before being hung up on wires to dry in large drying rooms and so further cure in the air. Typically this air-curing takes 2.5 years, but the hams can be dried in this way for 5 years. Periodically, the hams are taken down, the mould growth is scraped off with oil, and they are re-hung. Pork loin was also produced in the same plant. This is treated in much the same way, but is not hung for so long. There are grades of quality where Iberico ham is concerned, stemming from the treatment of the live pig. Organically produced animals command a 100% increase in price over non-organic animals, while pigs fattened exclusively on acorns in their final few months have an added value.

 

 

 

 

 

 

Click to play corn bunting song

Merino Sheep.

The merino is a breed of domestic sheep, Ovis aries which originated in Spain, probably in the 15th century, as a result of selective cross-breeding. The principal product of this selective breeding is the very fine wool, characteristic of the various types of merino sheep which exist today. Alongside the production of high-quality wool merino lambs are raised on the Dehesa, sent to a finishing plant to achieve the correct weight and slaughtered for food. Whilst on the Dehesa the sheep are guarded by large Spanish mastiff dogs (see photo below). They move around with the sheep, and were (and are still) used primarily to protect the flocks from wolves and bears during transhumance (the movement of livestock between summer and winter pasture). A defining characteristic of a ‘true’ mastiff is, apparently, the presence of a second dew claw.

To gain some deeper understanding of the process of merino wool production we visited a wool-processing plant in Villanueva de la Serena. Wool production in Spain is organised around a co-operative model. Farms join a co-operative (possibly up to 300 farms) and send all their wool together to the processing plant. The plant we visited deals with six co-operatives. At the plant the wool is graded by colour, cleanliness, weight and fibre-length. After receiving a flat rate initially for the wool, farmers may receive an additional payment for high-quality wool. There is a certain cachet associated with being part of a co-operative and a consequent drive to produce a good product to raise the profile of your co-operative. The corollary of this is that individual farmers can be removed from a co-operative if their wool isn’t up to standard. The final stage of wool processing is washing. Currently in Spain there is no facility for washing wool on this industrial scale. Non-organic wool is sent to Portugal to be washed, whilst, incredibly, organic wool has to go to Uruguay to be washed, and then sent back to the plant to be packed.

As noted, merino lambs are raised for meat, and we went to a lamb-finishing unit, not far from the wool-processing plant, to see the final stages of lamb production. This unit is part of a group that deals with eight lamb-producing co-operatives in Andalucía and Extremadura in a system very much like the wool-production model. Approximately 2000 individual farms are part of these eight co-ops, each farm having between 300 and 2000 head of sheep. The finishing units have a number of aims: first is to produce a product of consistent weight and quality for sale to the market. Typically lambs arrive weighing between 18 and 19 kg and are kept until they reach 28 kg, although they might get up to 35-40 kg for sale into Muslim and Jewish markets. Lamb consumption is low in Spain (1.5 kg per person per year) and most of the lamb produced in Spain is exported to Japan, Israel and the UAE. The aim is to be very precise in how much each individual lamb eats as food is very expensive. To that end they are trying to implement digitally-controlled feeding regimes via individual collars that control access to food. Secondly, they undertake research into genetics to improve the quality of the lambs. Another major focus is trying to use satellite data and digital communications to improve fine-scale land-use practise on individual farms, in an effort to reduce over-grazing in an environment already stressed by lack of water. They can provide data to farmers on when and where to move their sheep and when and how much supplementary feed to provide. It appears, however, that there is some reticence on the part of sheep-farmers to implement the work of the project. The move towards a satellite/digital data-driven system and away from a traditional human-based assessment of needs is a large hurdle to overcome.

Click to play Chaffinch song

Spanish Cattle.

The cattle breeds kept on the Dehesa San Francisco are the berrendo (red and black) and the retinto. Spanish fighting cattle are raised on neighbouring estates. These cattle are the third livestock component in the agrosilvopastural system. At Dehesa San Francisco however the focus is very much on the pig and sheep production and we did not encounter or discuss much concerning the cattle. In general, they are very much left to graze unattended and sold for meat.

Click to play Short-toed Treecreeper song

The Cork Oak.

Essential to the effective functioning of agrosilvopasturalism is the cork oak Quercus suber. Whilst other oak, Quercus, species will provide shade, maintain soils, prevent water loss and produce acorns to feed pigs and so develop the distinctive and valuable pork, the system arguably would not function economically without the sale of cork from the cork oaks.

To learn more about the production and uses of cork we went to the Instituto del Corcho, la Madera y el Carbón Vegetal in Merida, where we were given a talk about the harvesting and uses of cork, and a hands-on demonstration concerning the properties of cork in the research laboratory.

Six species of oak grow in Extremadura and Andalucía, but two species are important in the agrosilvopastoral system (the two evergreen species), cork and holm oak. Only the cork oak develops the thick bark which is harvested to produce cork. It is thought that the cork oak evolved its distinctive bark as a defence against frequent forest fires, protecting the tree long enough for the fire to pass through without doing permanent damage. As such, it has useful thermal insulation properties – one beneficial aspect being investigated at the Cork Institute.

The process of harvesting bark from a cork oak tree which can then can be used as a stopper in bottles is stretched over a long period of time and must be quite precisely controlled. As such the development of the method must necessarily have been rather opaque with many discarded permutations, not dissimilar to the smelting of iron ore to produce iron. It is the hydrophobic and elastic nature of cork that which allow it to be used as a highly effective bottle stopper, properties that have been recognised and exploited for over four thousand years. Cork was also the material studied under a microscope by the scientist Robert Hooke and in which he distinguished and named a fundamental building block of all living organisms – the cell.

The first harvest from a cork oak is called the corcho bornizo, the virgin cork. Cork is harvested during the late spring and summer, when the movement of sap in the tree allows a clean separation of the bark. The tree must be at least 25 years old when this first harvest is taken, and the bark produced has very low value, and no utility at all as a bottle stopper. The return on this first harvest doesn’t cover the costs of harvesting. It is necessary, however, as it encourages the tree to regrow its bark, and this regrowth is denser. When the highly-skilled harvesters cut the bark, they only take it from the main trunk and the lower part of the main branches – normally up to a height of about 2-3 meters. The bark is harvested a second time – about 9 – 11 years later. Again, this harvest cannot be used in bottles, and is often ground-up to be used in tiles, insulation or decoration.

It is the third harvest which produces the first high-quality cork that may be used in bottles. The tree may be harvested every 9-11 years thereafter (by law it must not be less than 9 years), and can continue to produce cork for another 10-12 harvests until the tree is approximately 150 years old and bark regrowth slows and the tree becomes more susceptible to disease and fungal attack.

With momentum slowly beginning to move towards the use of so-called natural (i.e. non-oil-based) materials in insulation there is a tremendous opportunity to develop cork as a worthy alternative. Innovation continues in the way cork is used in bottles, including the use of shredded cork and corks composed of different grades of material. There are undoubtedly other used to be made of this unique material and the Institute aims to continue to investigate and innovate. All of this will help to support the continued use of cork, and therefore the continued growing of cork oak as a harvestable crop and an integral part of the Dehesa ecosystem.

Click to play Dehesa background sound

 

Conclusions.

Dehesa San Francisco is 700 ha in size, with approximately 50,000 trees – a 50/50 mix of cork oak and holm oak. Every year those trees ready for harvesting have their bark removed for cork production. Pigs roam extensively under the trees, rooting for food and devouring the acorns when they drop. Flocks of merino sheep graze, guarded by huge mastiffs, before they are moved across Spain to summer grazing in the North – the journey increasingly returning to the traditional transhumance and very much driven by Ernestine. Indeed, it is apparent that Ernestine is a driving force behind much of the innovation in approach at Dehesa San Francisco. Perhaps the main message after just a week of immersion in the Dehesa environment is the emphasis on producing a high-quality product: organic acorn-fed ham; well-fed, precisely finished lamb; top of the range wool and cork. There is a desire, it seems, to understand all aspects of the environment: the importance of the Dehesa both culturally and ecologically. Slightly peripheral to the farming side of the visit, but nevertheless important, is the ongoing work to encourage the return and protection of both griffon and black vultures, as well as red kites and spanish imperial eagles. It is an approach to land-use that recognises the value of what currently exists and seeks to improve it through complete understanding of all its facets.

Appendix.

Griffon Vulture

A complete list of bird species seen during the trip, including outside the Dehesa:

NAME SCIENTIFIC NAME NOTES
Red-legged Partridge Alectoris rufa
Common Cuckoo Cuculus canorus
Feral Dove Columba livia
Common Wood Pigeon Columba palumbus
Eurasian Collared Dove Streptopelia decaocto
White Stork Ciconia ciconia Roofs in towns and in Seville
Great Cormorant Phalacrocorax carbo Flying over the Dehesa
Grey Heron Ardea cinerea
Little Egret Egretta garzetta A flock of 6 flying over the accommodation
Griffon Vulture Gyps fulvus Various individuals near the vulture station
Cinereous (Black) Vulture Aegypius monachus One seen over the feeding station
Booted Eagle Hieraaetus pennatus
Black Kite Milvus migrans Ubiquitous in villages and towns
Tawny Owl Strix aluco Heard at night from the accommodation
Eurasian Hoopoe Upupa epops Only seen twice but heard every day
European Bee-eater Merops apiaster Birds seemed to return during our stay
Great Spotted Woodpecker Dendrocopos major
Lesser Kestrel Falco naumanni A pair flying over in Seville
Woodchat Shrike Lanius senator Common in the Dehesa
Eurasian Jay Garrulus glandarius Frequent in the Dehesa
Iberian Magpie Cyanopica cooki Frequent in the Dehesa
Northern Raven Corvus corax A few individuals over the hilltop
European Crested Tit Lophophanes cristatus
Eurasian Blue Tit Cyanistes caeruleus
Great Tit Parus major
Thekla’s Lark Galerida theklae Frequent feeding on the ground at hilltop
Barn Swallow Hirundo rustica
Common House Martin Delichon urbicum
Long-tailed Tit Aegithalos caudatus
Eurasian Blackcap Sylvia atricapilla
Garden Warbler Sylvia borin
Sardinian Warbler Curruca melanocephala One male near the accommodation
Western Subalpine Warbler Curruca iberiae One male near the accommodation
Eurasian Wren Troglodytes troglodytes
Eurasian Nuthatch Sitta europaea A few individuals – one in a nestbox
Short-toed Treecreeper Certhia brachydactyla A number around the Dehesa, singing
Spotless Starling Sturnus unicolor Common on the donkey fields
Mistle Thrush Turdus viscivorus
Common Blackbird Turdus merula
Common Nightingale Luscinia megarhynchos Very common all over
European Pied Flycatcher Ficedula hypoleuca
Blue Rock Thrush Monticola solitarius A pair in Aracena
European Stonechat Saxicola rubicola
House Sparrow Passer domesticus
Common Chaffinch Fringilla coelebs
European Goldfinch Carduelis carduelis
European Serin Serinus serinus
Corn Bunting Emberiza calandra Common, singing from treetops
Cirl Bunting Emberiza cirlus One male singing in a rain shower

It appeared that a number of migratory species were beginning to return to the area during our stay, including bee-eaters and many of the warblers. I have no doubt that had we been there 2-3 weeks later in the year we would have seen and heard more species and more individuals of each species.

 

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