Keywords

1 Introduction

Silvopastoralism is an ancient and traditional way of land management where trees, animals and pasture were integrated to meet human needs. Nowadays, ­silvopastoralism is promoted as a type of an agroforestry system due to economic, environmental and societal benefits derived from its multifunctionality (Rigueiro et al. 2008). Multifunctionality can be understood at both a temporal and spatial scale. It is feasible to combine the preservation of different aspects of biodiversity and fulfilling economic (higher profitability) and social requirements (rural population stabilisation) at the same time. The Agenda 21 global agreement of the UN Conference on Environment and Development in Rio de Janeiro proposed that agroforestry systems, including silvopastoralism are a form of sustainable land management that should be promoted (UN 1993). Moreover, a COUNCIL REGULATION on support for rural development by the European Agricultural Fund for Rural Development (EAFRD) was released (15 September 2005), which establishes that “measures targeting the sustainable use of forestry land through the first establishment of agroforestry systems on agricultural land” should be taken.

Silvopastoral systems can provide ecosystem services delivering biodiversity conservation and enhancement within an integrated and sustainable framework. This article starts with a review of the history of silvopastoral systems, then focusing on their benefits, particularly concerning biodiversity. Finally, it places ­silvopastoralism within a policy context and considers the potential impact of the management of these systems.

2 Brief History of Silvopastoral Systems

Silvopastoralism is one of the oldest agroforestry practices (Etienne 1996). In historical ecology several authors support the theory that natural western European forests may have been to a large degree grazed by wild large herbivores (Putman 1996; Vera 2000; Bradshaw et al. 2003). Such grazing had an influence on the forest structure and development. Later animal species were replaced by domestic livestock. Considering this hypothesis silvopastoralism can be understood as a natural practice, if well planned beforehand and if it mimics the grazing of wild animals.

As civilisation progressed towards stable patterns of agriculture, woodland grazing and silvopastoral systems were abandoned. However there was a continuous transfer of biomass fertility from forests to cultivated land via manure (Piussi 1994; Eichhorn et al. 2006). Branches of ash, elm, poplar and other species were collected and stored and oak acorns were used to provide fodder for livestock (Meiggs 1982; Ispikoudis et al. 2004; Eichhorn et al. 2006). Another reason for maintaining trees in the landscape was the production of fruit such as chestnuts for human consumption as an essential part of the diet (Herzog 1998).

Until the Middle Ages the maintenance of soil fertility was based upon a strict connectivity between agriculture, animal husbandry and forestry. Later on and especially in the twentieth century with the introduction of chemical fertilisers in most parts of Europe, soil fertility became less dependent upon the transfer of nutrients from woods (Eichhorn et al. 2006).

At that time silvopastoral systems were considered to have low productivity, hence forestry and agriculture developed quite independently. The industrialisation of the 1800s initiated the abandonment of traditional methods of land management favouring a more intense and homogeneous system (EEA 2006). The current ‘biodiversity crisis’ in western Europe results mainly from this drastic change in the long-term interaction between human activities and nature (Bradshaw and Emanuelsson 2004). It was not until the end of twentieth century when silvopastoral systems were again recognized as favourable as they ensured key ecosystem functions, such as soil improvement, nutrient recycling, biodiversity promotion as well as marketable products (SSM 2004; WFC 2004).

In European Mediterranean countries, silvopastoralism is a traditional and widespread land-use activity. For example, half of the so-called ‘forested area’ in Spain is covered by natural grasslands, shrub lands and open forests used traditionally for livestock. If productive forests with extensive livestock use are taken into account, this area increases up to 70%. Only a quarter of the Spanish forest area is exclusively used for timber production, where no livestock is allowed (MMA 2000). Keeping extensive livestock is an integrated and environmental-friendly land use system as it requires minimum infrastructures and buildings that would degrade the landscape and it mostly uses natural resources for the nutrition of the livestock.

3 Benefits Derived from Silvopastoral Systems

The benefits of silvopastoral systems have been widely reported and it is recognized that they coincide with the principles of multifunctionality and sustainability (Sibbald et al. 1994; Etienne 1996; Papanastasis et al. 1999; Mosquera-Losada et al. 2005; Rigueiro-Rodríguez et al. 2008).

Multiple use of forests may be defined in different ways. Two commonly accepted definitions are: (1) management of forests to obtain multiple products and benefits such as production, protection and conservation, (2) multiple use forestry takes an integrated approach towards the different categories of forests and encompasses the scientific, cultural, recreational, historical and amenity values of forest resources (Schuck et al. 2002). Thus, the concept of silvopastoralism falls clearly within the category of multifunctionality as it combines the timber production in an integrated system with livestock and/or pastures.

The derived benefits of silvopastoralism can be grouped according to their impact on the three sustainability pillars (Nair et al. 2008):

  1. 1.

    Economic pillar

    1. (a)

      Diversification of products (meat, wool, mushrooms, timber, cork …) ensures short- and long-term income

    2. (b)

      Enabling faster production of high-quality timber, e.g. Quercus robur L., Juglans regia L., Fraxinus excelsior L., Prunus avium L. etc.

    3. (c)

      Reducing the costs of silvicultural treatments as needs for mechanical ­clearing are reduced and pruning can provide extra fodder for animals

    4. (d)

      Livestock welfare and increased quality of animal products from diverse fodder resources and a spatially heterogeneous living environment

  2. 2.

    Social pillar

    1. (a)

      Helping to keep the population in rural areas and managing natural resources

    2. (b)

      Increasing landscape value for local residents and tourists

  3. 3.

    Environmental pillar

    1. (a)

      Contributing to biodiversity preservation

    2. (b)

      Recycling nutrients within the system, especially reducing nitrate and phosphorous leaching which is an important problem in the European Union

    3. (c)

      Preventing desertification and erosion

    4. (d)

      Reducing greenhouse gas emissions and acting as a carbon sink, when compared to intensively-managed agricultural systems

    5. (e)

      Decreasing risk of forest fires

The relative importance of each of these aspects may vary across different European climatic regions, e.g. Mediterranean regions, Atlantic with dry summers and Atlantic with humid summers (McAdam et al. 2005).

4 Biodiversity and Silvopastoral Systems

4.1 Preserving Biodiversity

Preserving biodiversity is maintaining its intrinsic value and the services that natural systems provide: food, fuel, fibre and medicines, regulation of water, air and climate, soil fertility, cycling of nutrients. Therefore the concern for biodiversity is integral to sustainable development and supports competitiveness, economic growth and employment and improved livelihoods (CEE 2006). According to the Millennium Ecosystem Assessment some two-thirds of ecosystem services worldwide are in decline due to over-use and the loss of species richness (Hassan et al. 2005), which is needed for their stability (EEA 2006).

Silvopastoral systems favour biodiversity from different aspects. In Europe there is variety of different combinations of tree and under-storey species and livestock, e.g. Eucalyptus globulus Labill, Pinus radiata D. Don, P. nigra JF Arnold or P. pinaster Aiton with shrubs of Ulex spp., Cytisus spp., Erica spp., and/or grasses grazed by horses, goats, sheep and cattle in northern Spain (Rigueiro-Rodriguez et al. 1997; McAdam et al. 1999; Casasús et al. 2007), Spanish and Portuguese dehesas of Quercus suber L. or Q. ilex L. with pigs or bulls (San Miguel 1994), pollarded Fraxinus excelsior with cattle in Spain and Sweden (Ispikoudis and Sioliou 2006), Quercus coccifera L. with goats in Greece (Schultz et al. 1987), wooded pastures in England (Rackham 2001), windbreaks in Denmark and Russia (Nair 1993), reindeer husbandry in Picea abies (L.) H. Karst or Pinus sylvestris L. forests in Finland and Siberia (Kumpula 2001; Harrop 2007).

This variety of different combinations can be partly explained by the gradients of stand and site characteristics (e.g. light, moisture, fertility) that create different microclimatic niches and spatial heterogeneity (Mosquera-Losada et al. 2006). However the development of the under storey species and biomass is also driven by factors such as the edaphoclimatic characteristics, predominant tree species, the pressure exerted by different animal species and the management practices carried out by the farmer. Silvopastoral systems can host agricultural and forest species, in this way they act as biological corridors between the different ecosystems, and as such they contribute to species maintenance and biodiversity enhancement (Luoto et al. 2003). This is of special relevance in fragmented landscapes.

Until recently, when conserving biodiversity, the emphasis has been on preserving habitats in natural areas by excluding human communities, rather than on protecting practices that have resulted from relationships between humans and nature (Harrop 2007). This has been the response to the observed exceeding of the carrying capacity of the ecosystem in some cases. Nowadays it has been realized that management should mimic traditional agricultural practices to secure the persistence of species that depend upon the human-induced habitat (Harrop 2005a, 2007). The FAO project Globally Important Agricultural Heritage Systems (GIAHS) emphasises the protection of: (1) human practices which contribute to the creation and maintenance agricultural diversity, (2) landscapes that have resulted from the long lasting relationships between humans and the natural world, and (3) the human cultural heritage, that forms the foundations for the traditional practices. Examples of GIAHS sites include among other, silvopastoral systems like reindeer herding in Siberia or the dehesas in Southern Spain and Portugal (Harrop 2005b).

4.2 Birds and Silvopastoral Systems

Certain areas in Europe, between intensively-managed agricultural land and the abandoned farmland, contain a patchwork of semi-natural and natural habitats and varied farmland, hosting a high diversity of species. Those areas are known as ‘high nature value farmlands (HNV)’ and are considered as key areas for wildlife. Such farmlands occur in association with traditional cropping systems as well as with livestock grazing systems on semi-natural habitats (EEA 2006). Among those are, e.g. the above mentioned dehesas, which are open Iberian forests and are considered to be one of the most important habitats for biodiversity in Europe (Moreno and Pulido 2008). They contain many species listed under the Habitats Directive (EC 1992), especially birds and mammals (Bunce et al. 2004). Holm oak (Quercus ilex) dehesas are one example, being one of the last breeding refuges for endangered bird species like the imperial eagle (Aquila adalberti Brehm) and the black vulture (Aegypius monachus L.) (Díaz et al. 1997), and a favoured wintering site of some species like the common crane (Grus grus L.) (Avilés 2004). If those ­practices are abandoned some of the species (e.g. vultures) might decline in abundance, as has already happened with the bearded vultures (Gypaetus barbatus L.) (EC 2000; EEA 2006).

The diversity of certain bird species is known to be a good indicator of ecosystem biodiversity. While the number of forest-related bird species has barely changed, bird species commonly associated with farming have been continuously decreasing (EEA 2006). Today only 70% of the species found in Europe in 1980 remain. The decline can be largely ascribed to agricultural intensification. It is estimated that 40% of the endangered bird species in Europe are threatened because of agricultural intensification and 20% by abandonment (EEA/UNEP 2004). Farmland birds are widespread across Europe, but there are particularly large numbers associated with extensive systems in Southern Europe. With expected large-scale land abandonment of marginal agricultural land it is likely that these bird species will decline (Casals et al. 2008). While the most favourable conditions for the diversity of farmland species are considered to occur under extensive and/or traditional agricultural management (EEA 2006).

Also many different passerines and raptors are found in these extensive systems. McAdam et al. (1999) observed that pastures with wide spaced trees and grazed by sheep could enhance higher diversity of birds, beetles and spiders than pastures without trees.

Another important factor related to the diversity of birds is the number of beetle species as they represent one of their important food sources. Silvopasture has been shown to encourage greater numbers of beetles than comparable grasslands (McAdam et al. 1999). The invertebrates are important components of the ecosystems, enhancing­ the species variety and population size of farmland and forest birds.

Preserving diversity will contribute to the maintenance and resilience of silvopastoral systems, enabling the production of goods and services (cultural, food, medicines, carbon sequestration, water, etc.) and contributing to the European target of halting the loss of biodiversity by the year 2010.

4.3 Livestock Biodiversity

Both wild and domesticated animal species are suitable for silvopastoralism. Especially with regard to conservation of indigenous domestic breeds silvopastoralism can play an important role. Mosquera-Losada et al. (2005) stated that half of the European indigenous domestic breeds are threatened by extinction. Further, the EEA (2006) reports that, in western Europe, 91% of mountain breeds of sheep are threatened by crossbreeding for improved of meat and milk production qualities, and by abandonment of traditional husbandry systems. The switch to modern breeds has led to the abandonment of remote pastures in many areas and the loss of biodiversity that depends on grazing (EEA 2006). High nature value pastoral grazing systems depend on locally adapted old livestock breeds which are better adapted to harsh natural conditions and extensive practices.

4.4 Grazing Damage Versus Biodiversity Enhancement

The Temperate and Boreal Forest Resources Assessment (UNECE/FAO 2000) reports that close to 2 million hectares, has been damaged by wildlife and grazing, i.e. approximately 0.2% of total forest and other wooded land area. Although it is not specified what share of damage is due to domestic livestock and the species involved, nor is the degree of the damage or the age of damaged trees listed.

There are broad concerns that excessive grazing in forests can cause harmful changes through reduction in structural complexity and species richness (Anderson and Radford 1994; Summers et al. 1997; Milne et al. 1998; Kuiters and Slim 2002; Milner et al. 2002; Mysterud and Østbye 2004). The intensity of the browsing impact determines whether forests are capable of regeneration. Regenerating trees will develop into high canopy trees or they remain as scrub and bushes (Pollock et al. 2005). To avoid a high degree of browsing of trees, the stocking rates have to be related to site characteristics and the forage quality and quantity considered (Pakeman et al. 2003; Mosquera-Losada et al. 2006). Damage depends on the type and number of animals, the fodder available and the seedling species and abundance.

Grazing removes some dominant, strong competitors, leaving space for weak competitors thus the dominance pattern becomes more even (Virkajärvi et al. 1996). The patches of bare ground caused by grazing, trampling and dunging offer a niche for seed germination. As already mentioned overgrazing can cause problems with regeneration and reduce ecosystem quality. But also complete exclusion of grazing can diminish species diversity, as some ground-dwelling species can dominate and shade out the tree seedlings or other ground species. A light grazing regime can help to regulate the competition between species and the shade from shrubs, allowing establishment of grass. For example a stand could be grazed for 1–2 years and then left ungrazed for around 10 years to allow tree saplings to establish (McEvoy et al. 2005).

For stock and vegetation management it must be borne in mid that different animal species have different preferences regarding vegetation. Goats and horses mainly feed on shrubby vegetation and might create more damage to trees, although problems mainly emerge when they are stocked at high density. Cows and sheep in general feed on herbaceous vegetation or young woody vegetation. However sometimes even within the same animal species there are different behavioural traits exhibited by breeds, e.g. there is a cattle breed from Navarra, Spain, that never damages young poplar and a sheep breed from England that does not browse coniferous trees.

Generally, livestock damage trees, so in some countries grazing is not permitted within the forests, e.g. in Slovenia (Official Journal 1993). Damage usually occur during establishment of the forest or the regeneration period though adult trees may also suffer damage to some extent. Damage can be alleviated through appropriate choice of animal and tree species, forest management and adequate stocking rate and grazing pattern (e.g. continuous vs intermittent). Keeping damage levels to a bearable limit may not hinder the sustainability of the system, providing a balance between production and conservation of natural resources. Large herbivores ­coexisted in the forest before human activity, creating branch or stem wounds needed as food and habitat for certain insects and other decomposing organisms and opening gaps needed for regeneration of light-demanding species (Bradshaw et al. 2003). Sometimes the wounds created do not affect timber quality. In some other minor cases, debarking for instance could cause the death of some trees, usually associated with incorrect selection of animal species and overgrazing. Nowadays the role of the standing and/or forest deadwood is increasingly recognized as up to 30% of the European forest species depend on old trees and deadwood for their survival (Dudley and Vallauri 2004). Deadwood provides habitat, shelter and food for birds, bats and other mammals and is particularly important for the less visible majority of forest dwelling species: insects, especially beetles, fungi and lichens. Increasing the amounts of deadwood in managed forests and allowing natural dynamics would contribute to sustaining Europe’s biodiversity (Dudley and Vallauri 2004). Therefore a certain level of damage to the trees by the animals should not always be considered as a problem, particularly if biodiversity is one of the objectives.

Grazing in woodlands or forests has been recognized as beneficial for biodiversity (Mitchell and Kirby 1990; Kirby et al. 1994; Mayle 1999; Bengtsson et al. 2000; Kampf 2000). Studies from Northern Europe show the positive effect of cattle grazing within the forests. In Finland forest pastures were a common practice until the 1960s when intensification of farming took place. Tuupanen et al. (1997) observed that cows grazing in the forest pastures could increase vegetation diversity compared to un-grazed forest when kept at a low stocking rate while also permitting economic levels of cattle production. Tuupanen et al. (1997) also noticed that forest areas encourage a more diverse animal behaviour (foraging, exploration, autogrooming) than in open meadows where the livestock spent more time standing inactive. Hence silvopastoral systems are beneficial for animal welfare, which is considered one of the main objectives within the Common Agricultural Policy of the European Union (CEC 2005). Hokkanen et al. (1998) studied the effect of grazing on Carabidae, which are species very sensitive to environmental changes, in meadows and forest pastures under open birch forest and dense forest with birch, pine and alder. Within forest pastures the number of both individuals and species of Carabidae increased in grazed compared to ungrazed areas. The Shannon diversity index was consistently higher in birch forest that the pine and alder and there was a larger total number of Carabidae species compared to the non-grazed boreal forests. Selective grazing seems then to increase the number and diversity of Carabidae species in the forest, even after a few years. This might be due to an opening of suitable niches, because many species favour open biotopes, while keeping the stocking rate low. McEvoy et al. (2005) have found that regeneration of oak seedlings under pine stands may be facilitated by previous grazing. It is in the first stages of the regeneration period or plantation establishment when most attention must be paid to livestock using individual protectors or temporal exclusion to allow the development of the saplings. In Australia light grazing in buloke (Allocasuarina leuhmannii Baker) forests encouraged the livestock to feed on the weed competing with the trees. These tend to be mainly exotic species and the reduction in herbicide, alternating with ungrazed periods for the regeneration of trees benefits the ­environment (Maron and Lill 2005). Moreover, Mediterranean wood pastures have traditionally maintained their open structure with livestock grazing. Well-planned grazing can have a positive impact on structure and species diversity in forests (Putman 1996; Hadjigeorgiou et al. 2005).

Livestock production has to be considered along with socio-economic and ecological objectives when designing sustainable grazing management. It is first necessary to determine the type of animals and grazing regimes to optimise the use of the available forage resources (Hadjigeorgiou et al. 2005; Casasús et al. 2007).

4.5 Silvopastoralism Preventing Forest Fires

Integrated systems such as these, where pastoralism is an active part of the forest management, help also to preserve biodiversity as they reduce forest fire risk. Forest fire policy has up to now been based on extinction, not on prevention. But due to the current trends of increasingly more damaging forest fires than previously climate change and desertification, a new policy attitude might address a more prevention-oriented management, e.g. clearing the forest either mechanically or, as it occurs already in some forests, using cattle or other livestock species to reduce understorey fuel. Some of the variables that influence occurrence of fires are weather, ignition source and characteristic and amount of fuel material. The latter can be controlled by livestock. Fires can cause loss of human life, biodiversity loss (species, habitats, landscape) and economic losses including ecotourism etc. and contribute to global warming. As consequence of the policy initiatives based on prevention, the amount of land burnt in France each year has been reduced by half between the 1980s and 1990s due to land use management practices with stronger fire prevention measures. It was considered that rural land use should aim at maintaining the traditional land mosaic of Mediterranean areas (forest, pastures and agricultural land), as perhaps the best option to prevent the propagation of large fires (EEA 2003). The option of using livestock instead of (or complementing) mechanical or chemical control to maintain firebreaks cleared of shrubs and trees is potentially important and is already subsidized in some regions, e.g. in eastern and southern Spain (Dopazo and Suárez 2004; Robles et al. 2008).

Some studies have shown that after several years of grazing in rangelands or forest pastures the herbage biomass is lower and had a smaller proportion of dead vegetation and therefore higher quality for grazing over a longer period than in the areas where grazing was excluded. It also prevents scrub encroachment, reducing the fire risk and maintaining the recreational value of forests (Hope et al. 1996; Adezábal, 2001; Bernués et al. 2005; Casasús et al. 2007). Grazing is a cost-­effective instrument to manage abandoned land and prevent the appearance of ­different and often irreversible environmental hazards to which these areas are highly susceptible (Casasús et al. 2007).

5 Silvopastoralism Within a Policy Context

One of the priority objectives of the EU is optimising the use of available measures under the reformed Common Agrarian Policy (CAP), notably to prevent intensification or abandonment of High-Nature-Value farmland, woodland and forest and supporting their restoration (EEA 2006).

It has traditionally been considered that silvopastoralism and agroforestry are more important land-use systems in developing countries where subsistence farming is a priority. In the last decades the value of silvopastoralism and agroforestry are becoming more widely recognized in developed countries due to the benefits of less intensive land uses (Nair et al. 2008). Threats to biodiversity in Europe are a high degree of habitat fragmentation, intensive agriculture, land and biodiversity-friendly traditional practices abandonment, climate change, desertification and fires (EEA 1998, 2006). Silvopastoral systems may contribute to combat these as well as to preserving domestic livestock breeds. There is therefore a slight change towards recognizing the cultural, social, economic and environmental value of traditional systems, e.g. silvopastoralism, as it fulfils most of the policy goals of sustainable land management. At a global level, silvopastoral systems are recognised in the Agenda 21 (UN 1993), in the Orlando Declaration on agroforestry systems (WFC 2004) and in the Lugo Declaration specific on silvopastoralism (SSM 2004). All these documents are landmarks in the recognition of the multiple benefits and future needs of these systems. Neither society, forest owners nor policy-makers should overlook the opportunity silvopastoral activities create, beyond those of traditional forests. They contribute to keeping people in rural areas, combat forest fires from the prevention point of view and they contribute to the “2010 target” of halting the loss of biodiversity which the EU is committed to. The most important policy instrument for the implementation of silvopastoral systems is the Council Regulation on support for rural development by the European Agricultural Fund for Rural Development (EAFRD) (Council Regulation 1698/2005) and the Proposal for a Council Decision on Community Strategic Guidelines for Rural Development (Programming period 2007–2013) (COM(2005)304 final) from the European Union as for the first time there is an opportunity to fund farmers for the establishment of agroforestry systems (art. 41). This policy also allows finance to be directed the conservation local breeds in danger of being lost to farming extinction (art. 37). The decline in traditional livestock breeds has negative implications for the management of semi-natural habitats that have been shaped by agricultural practices. On average 18% of the Natura 2000 area belongs to habitat categories which depend on a continuation of extensive agricultural practices. Such practices can be supported via agri-environment schemes and other agricultural policy instruments (EEA 2006).

The Action Plan on the Protection and Welfare of Animals of European Community aims to promote animal welfare in the future. General minimum standards for the protection of farm animals have already been set in the Directive 98/58/EC. These rules reflect the “five freedoms”: freedom from hunger and thirst, freedom from discomfort, freedom from pain, injury and disease, freedom to express normal behaviour, and freedom from fear and distress. In 2003, CAP reform introduced certain measures to promote the better handling and treatment of animals (EC 2006).

According to a Eurbarometer survey, EU consumers are willing to make an extra effort to buy animal welfare friendly products. Within the EU-27 and Turkey and Croatia, 62% of respondents would change their shopping habits in order to access more animal welfare friendly goods. The survey demonstrates general support for financially rewarding EU farmers who use better animal welfare practices. The well-being of animals during the production of food appears to be strongly associated with the healthiness and quality of products. Half of the people consider that high animal welfare standards produce healthier and better quality food (EC 2007).

Compensation in the form of rewards or payments to farmers who through their conservation efforts provide ecosystem services to wider society may also foster conservation (Jackson et al. 2007; Pascual and Perrings 2007).

6 Conclusion

While grazing in forests is still a controversial practice due to the potential for damage to the tree stock from the livestock, it is feasible under certain conditions to maintain a sustainable forest management where livestock and biodiversity conservation are part of an integrated system, which is multifunctional and which has several advantages over each of the individual components (forest and agriculture). Such multifunctional management will require more complex management input but will help promote sustainable development in rural areas, as a win-win alternative for Europe in the three elements of sustainability: economic, social and environmental. One of the key issues it to match the appropriate stocking rate for each site depending on the vegetation, animal species, productivity, environmental benefits including biodiversity conservation and enhancement and the multifunctionality of a suite of integrated outputs.