Misplaced Pages

#522477

37-553: A dehesa ( Spanish pronunciation: [de'esa] ) is a multifunctional, agrosylvopastoral system (a type of agroforestry ) and cultural landscape of southern and central Spain and southern Portugal ; in Portugal, it is known as a montado . Its name comes from the Latin defensa (fenced), referring to land that was fenced and usually destined for pasture. Dehesas may be private or communal property (usually belonging to

74-559: A 70-year period, identifying overgrazing, global changes, and the ecological effects of megafauna extinction as key factors. Their findings shed light on the multifaceted drivers behind changes in savannah ecosystems. Echoing this theme of alternative strategies to combat overgrazing, Kriegisch et al. (2019) demonstrated how drift- kelp availability could reduce the foraging movement of overgrazing sea urchins, suggesting that alternative food sources may significantly influence grazing behaviors and aid in managing marine ecosystem pressures. In

111-470: A pasture can limit the ability to use that land for other purposes in the future. Integrating pasture into existing woodland presents challenges as well: the woodland likely needs to be thinned to increase light infiltration, which is time consuming and may require heavy machinery , as well as a strategy for dealing with felled trees. Thinned woodlands are also likely to experience a flush of growth in weeds and seedling trees that must be dealt with to prevent

148-470: A similar vein, the research by Cai et al. (2020) presents a stark example of the terrestrial impact of overgrazing, showing how the fertile island effect collapses under extreme conditions in shrub-encroached grasslands . This case study emphasizes the critical need for sustainable grazing practices to protect soil health and maintain ecosystem functionality, further illustrating the wide-reaching consequences of overgrazing across diverse habitats. Overgrazing

185-451: A typical dehesa, oaks are managed to persist for about 250 years. If cork oaks are present, the cork is harvested about every 9 to 12 years, depending on the productivity of the site. The understory is usually cleared every 7 to 10 years to prevent the takeover of the woodland by shrubs of the rock rose family ( Cistaceae ), often referred to as " jara ", or by oak seedlings. Oaks are spaced to maximize overall productivity by balancing light for

222-458: Is a massive threat to the native species of flora and fauna, especially the native bushes which are often overlooked by invasive species looking for homes. Mustalids, rabbits, hares and possums often eat the plants that hold soil together. This makes the ground very unstable and crumbly. If soil is unstable, it is prone to collapse in extreme weather events such as floods and heavy rain. This is detrimental to farmers of crops and animals alike. 40% of

259-507: Is considered the main cause of woody plant encroachment at the expenses of grasses on a land area of up to 45 million hectares. In many arid zones in Australia , overgrazing by sheep and cattle during the 19th century, as pastoralism was introduced by European settlers, caused many long-lived species of trees and shrubs to give way to short-lived annual plants and weed species. Introduced feral rabbits , cats and foxes exacerbated

296-459: Is increased farmland utilization - silvopasture can incorporate unused woodlands into production and produce multiple products on the same acreage. This diversifies farm income sources and increases farm viability. Silvopasture has been found to increase wildlife abundance and diversity. Trees in silvopasture systems provide livestock with protection from sun and wind, which can increase animal comfort and improve production. Trees can provide shade in

333-645: Is used as an example in the economic concept now known as the Tragedy of the Commons devised in a 1968 paper by Garrett Hardin . This cited the work of a Victorian economist who used as an example the over-grazing of common land. Hardin's example could only apply to unregulated use of land regarded as a common resource. Normally, rights of use of common land in England and Wales were, and still are, closely regulated, and available only to "commoners". If excessive use

370-467: Is usually cork , a sustainable product that supports this ancient production system and old growth oaks. Dehesas cover nearly 20,000 square kilometers on the Iberian Peninsula , mainly in: [REDACTED] Media related to Dehesas at Wikimedia Commons Agrosylvopastoral Properly managed silvopasture (grazed woodland) can increase overall productivity and long-term income due to

407-591: The American bison of the Great Plains , or migratory wildebeest of the African savannas , or by holistic planned grazing. Overgrazing typically increases soil erosion . With continued overutilization of land for grazing, there is an increase in degradation. This leads to poor soil conditions that only xeric and early successional species can tolerate. A meta-analysis of 148 studies found that

SECTION 10

#1732765700523

444-576: The ancient woodlands of Scotland , such as Rassal Ashwood in Ross-shire , and at Glen Finglas in the Trossachs . The Dalkeith Old Wood, belonging to the Duke of Buccleuch , cattle grazing beneath ancient oak , is designated as a Site of Special Scientific Interest ( SSSI ) (or 'ASSI'). Epping Forest is one of the principal remnants of wood pasture in England. Here, the grazing of cattle

481-524: The 20th century, and are still-widespread in some areas. Wood pasture, one of the oldest land-use practices in human history, is a historical European land management system in which open woodland provided shelter and forage for grazing animals, particularly sheep and cattle , as well as woodland products such as timber for construction and fuel, coppiced stems for wattle and charcoal making and pollarded poles . Since Roman times, pigs have been released into beech and oak woodlands to feed on

518-575: The Mongolian steppes, Liu et al. (2013) found that approximately 60% of vegetation decline could be attributed to climate factors, with the rest significantly influenced by increased goat density due to overgrazing. This points to a complex interplay between climate change and grazing practices in ecosystem degradation. Further expanding our understanding, Stevens et al. (2016) investigated woody encroachment in South African savannahs over

555-536: The acorn and beech mast, and into fruit orchards to eat fallen fruit. Tree species and planting densities are studied over a range of sites at The Silvopastoral National Network Experiment. Natural England 's Environmental Stewardship scheme defines Wood Pasture, in the Farm Environmental Plan booklet, as a structure of open grown or high-forest in a matrix of grazed-grassland, heathland, and/or woodland floras. Their experience shows sheep use

592-405: The biodiversity. Turning to the aquatic environment, Ling et al. (2015) have documented the phenomenon of catastrophic sea urchin overgrazing and its role in marine ecosystem regime shifts. Their study underscores the urgent need for effective management and conservation strategies to mitigate the profound ecological impacts of overgrazing, highlighting the issue's global scope. Similarly, on

629-505: The combination of shade from trees and water uptake from tree roots may reduce drought impacts. Silvopasture is compatible with fruit, nut, and timber production. Grazing can serve as a cost-effective vegetation and weed control method. Silvopasture can also help reduce pests and disease in orchards - when introduced into an orchard after harvest, livestock are able to consume unharvested fruits, preventing pests and diseases from spreading via these unharvested fruits and in some cases consuming

666-616: The genus Quercus ( oak ), such as the holm oak ( Quercus rotundifolia ), although other tree species such as beech and pine trees may also be present. Oaks are protected and pruned to produce acorns , which the famous black Iberian pigs feed on in the autumn during the montanera . Ham produced from Iberian pigs fattened with acorns and air-dried at high elevations is known as Jamón ibérico (" presunto ibérico ", or "pata negra" in Portuguese), and sells for premium prices, especially if only acorns have been used for fattening. In

703-595: The grasses in the understory, water use in the soils, and acorn production for pigs and game. The dehesa is in many ways similar to the California oak woodland , although the former is typically much more intensively managed. The dehesa system has great economic and social importance on the Iberian Peninsula because of both the large amount of land involved and its importance in maintaining rural population levels. The major source of income for dehesa owners

740-494: The most-viable and prominent agroforestry practice in the United States. In the south eastern USA, longleaf pine / wiregrass restoration projects have trialled the effects on both economics and ecology of grazing cattle among the trees. This fire-resistant tree species originally grew at low density so that understory plants were available to browsing animals. The region was used as silvopastures by Spanish settlers from

777-625: The municipality). Used primarily for grazing, they produce a variety of products, including non-timber forest products such as wild game , mushrooms , honey , cork , and firewood . They are also used to raise the Spanish fighting bull and the source of jamón ibérico , the Iberian pig . The main tree component is oaks, usually holm ( Quercus rotundifolia ) and cork ( Quercus suber ). Other oaks, including melojo ( Quercus pyrenaica ) and quejigo ( Quercus faginea ), may be used to form dehesa,

SECTION 20

#1732765700523

814-443: The pasture from being overgrown. Pasture forages may also need to be established beneath the trees, a process which can be difficult if trees have already been felled. According to the wood-pasture hypothesis , open, grazed woodlands of some form or another would have been part of the original European wildwoods even before they were used by humans. Fruit and nut and silvopasture systems covered large portions of central Europe until

851-426: The pests themselves. Silvopasture can be established by planting trees into existing pasture or by establishing pasture in existing woodland . The two methods differ significantly in the challenges they present. Planting trees into existing pasture presents several challenges: young trees must be protected from livestock, trees may take years to become productive (depending on the species), and planting trees in

888-826: The residual longleaf pine forests and land restoration projects, with evidence that the multiple income streams of timber and cattle are economically advantageous, along with wildlife restoration benefits. The legal protection of some species (e.g. red-cockaded woodpecker ) that can be found in this habitat means that landowners may be able to add financial compensation as a further source of income. Overgrazing Overgrazing occurs when plants are exposed to intensive grazing for extended periods of time, or without sufficient recovery periods. It can be caused by either livestock in poorly managed agricultural applications, game reserves , or nature reserves . It can also be caused by immobile, travel restricted populations of native or non-native wild animals . Overgrazing reduces

925-456: The simultaneous production of tree crops, forage, and livestock, and can provide environmental benefits and has been practiced in many parts of the world for centuries. Silvopasture is not the same as unmanaged grazing in woodlands. Open pasture systems are a result of mass deforestation, decreasing water availability, and increasing soil nutrients to a point that is damaging both to the ecosystem and to humans. A primary benefit of silvopasture

962-562: The sixteenth century and this use continued into the early twentieth century, along with felling trees for timber. By the 1920s, most of the longleaf pine which once dominated around 92 million acres (about 37 million hectares) of ground between the states of Texas and Virginia had been cut down by European settlers. Removal of the trees, and loss of their associated ecosystem , led to significant soil erosion as well as replacement with dense commercial tree plantations and open agricultural fields. There has been continuing interest in silvopastures in

999-490: The species utilized depending on geographical location and elevation. Dehesa is an anthropogenic system that provides not only a variety of foods, but also wildlife habitat for endangered species such as the Spanish imperial eagle . The dehesa is derived from the Mediterranean forest ecosystem , consisting of grassland featuring herbaceous species, used for grazing cattle, goats, and sheep, and tree species belonging to

1036-429: The summer and windbreaks in the winter, allowing livestock to moderate their own temperature. Heat stress in livestock has been associated with decreased feed intake, increased water intake, and negative effects on production, reproductive health, milk yields, fitness, and longevity. Certain tree types can also serve as fodder for livestock. Trees may produce fruit or nuts that can be eaten by livestock while still on

1073-872: The surrounding land in Australia. In the Caribbean region, overgrazing is a threat to vegetation areas where there is livestock farming, which is an important source of livelihood and food security for many people. a combination of small scale livestock farming with small ruminants, and mixed farming is practised. However, livestock consume vegetation faster than it can be renewed and this leads to land degradation, loss of vegetative areas, and soil erosion resulting in poor quality feed and reduced livestock yields and income. Also, these grazing lands are critical in controlling carbon dioxide and mitigating risks against severe weather such as floods and droughts. Overgrazing weakens ecological conservation. In New Zealand , overgrazing

1110-611: The threat to both flora and fauna . Many bird species have become extinct or endangered, and many of the medium-sized desert mammals are now completely extinct or only exist on a few islands of Australia . Overgrazing can also occur with native species. In the Australian Capital Territory , the local government in 2013 authorised a cull of 1455 kangaroos due to overgrazing. Maisie Carr (1912-1988), Ecologist and Botanist, undertook significant research and studies in overgrazing and established consequences on

1147-702: The tree or after they have fallen. The leaves of trees may serve as forage as well, and silvopasture managers can utilize trees as forage by felling the tree so that it can be eaten by livestock, or by using coppicing or pollarding to encourage leaf growth where it is accessible to livestock. Well-managed silvopasture systems can produce as much forage as open-pasture systems under favorable circumstances. Silvopasture systems have also been observed to produce forage of higher nutritive quality than non-silvopasture forage under certain conditions. Increased forage availability has been observed in silvopasture systems compared to open-pasture systems under drought conditions, where

Dehesa - Misplaced Pages Continue

1184-402: The trees for shelter from wind. This could provide significant animal-welfare benefits. However, 'sheep time' close to trees results in soil compaction with the greatest-compaction after trees are planted at very-low densities. Some botanists recommend trees be planted at no-less than 400 per hectare to ensure good-establishment. Evidence of old wood-pasture management is detectable in many of

1221-693: The use of common land in England and Wales was a triumph of conserving a scarce resource using agreed custom and practice. There have been overgrazing consequences in the region Sahel region. The violent herder–farmer conflicts in Nigeria , Mali , Sudan and other countries in the Sahel region have been exacerbated by land degradation and overgrazing. See 2010 Sahel famine . Various countries in Sub-Sahara Africa are affected by overgrazing and resulting ecological effects. In Namibia , overgrazing

1258-442: The usefulness, productivity and biodiversity of the land and is one cause of desertification and erosion . Overgrazing is also seen as a cause of the spread of invasive species of non-native plants and of weeds . Degrading land, emissions from animal agriculture and reducing the biomass in a ecosystem contribute directly to climate change between grazing events. Successful planned grazing strategies have been in support of

1295-483: The value of most ecosystem functions declines with increasing grazing intensity and that increasing aridity weakens positive impacts of light grazing. Native plant grass species, both individual bunch grasses and in grasslands , are especially vulnerable. For example, excessive browsing by white-tailed deer can lead to the growth of less preferred species of grasses and ferns or non-native plant species that can potentially displace native, woody plants, decreasing

1332-478: Was combined with the pollarding of trees for fuel, both for domestic consumption and for sale. This system continued in the parish of Loughton until banned in 1879. The town's public hall, built with compensation money for the ending of the custom, is called the Lopping Hall in memory of the practice. Controlled cattle grazing and limited pollarding is still carried out by the conservators. Silvopastures are

1369-433: Was made of common land, for example in overgrazing, a common would be "stinted", that is, a limit would be put on the number of animals each commoner was allowed to graze. These regulations were responsive to demographic and economic pressure; thus rather than let a common become degraded, access was restricted even further. This important part of actual historic practice was absent from the economic model of Hardin. In reality

#522477