Characteristics

Characteristics of grazing land: general

2012-06-12T11:35:12+00:00

Authors: Conceptión Alados, Erea Paz, Frederico Filliat, Maite Gartzia

{xtypo_alert}Editor's note: Text extracted from D211-2.1{/xtypo_alert}

According to Food and Agriculture Organisation of the United Nations FAO (1996) about one-quarter of the world's total land area is used for grazing livestock and one fifth of the world's arable land is used for growing cereals for livestock feed. Together this makes livestock production one of the largest land uses in the world. Grazing ecosystems provide both market services, such as livestock production and genetic resources, and non-market services, such as landscape, recreation and culture. The importance of these non-market services is often higher than the grazing services, as for example reported by Fleischer and Sternberg (2006) in Israel, where urban populations value the green landscape of rangelands in the Mediterranean climate region and are willing to pay for conserving it in light of the expected increasing aridity conditions in this region.

Rangeland ecosystems are complex systems composed of different subsystems that interact with each other, resulting in patterns and processes that cannot be understood by analysis of their individual parts alone. Rangeland systems involve interactions between ecological, economic and social forces in a non-linear way. Fundamental processes of land degradation and desertification in grazing land are driven by positive feedbacks (causing regime shifts). The effect of domestic grazing has variable effects on ecosystem structure and processes, which may depend on the long evolutionary histories of grazing (Milchunas et al. 1988; Perevolotsky and Seligman 1998; Adler et al. 2004; Adler et al. 2005). In ecosystems with a long evolutionary history of grazing, vegetation is adapted to large herbivores and consequently, livestock grazing may even be necessary to maintain ecosystem biodiversity (McNaughton 1979; Naveh and Wittaker 1979; Collins 1987). Only under permanent overgrazing were traditional herd management practices believed to be environmentally destructive (Hary et al. 1996). There is evidence of irreversible land degradation in systems that evolved under high grazing pressure, such as African deserts and savannas (Milton et al. 1994; Illius and O'Connor 1999; Tobler et al. 2003) or Argentinean rangelands (Cingolani et al. 2005; Cingolani et al. 2008). Rangeland livestock systems are also considered to degrade when they are affected by climatic variability, especially in arid and semi-arid areas. Climatic variability is the largest cause of poverty in pastoral societies (Ellis et al. 1993; Aidoud et al. 1998; Koukoura et al. 1998; Ward et al. 1998).

Livestock do not use the landscape homogeneously, but have preferred areas, which results in uneven distribution of animal impact. Landscape heterogeneity increases as grazing intensity increases, resulting in heavier impacts on preferred areas. In traditionally managed grazing systems, mobile pastoralism provides a way to respond to variations in intra- and inter-annual climatic fluctuations (Fryxell and Sinclair 1988) and prevent desertification by overgrazing (Homann et al. 2008). In areas where traditional grazing is not the case, as in USA rangeland ecosystems for example, rotational grazing has been proposed as a remedy for deterioration due to patch grazing (Kirkman and Moore 1995; Teague and Dowhower 2003). This practice is also used in Australian arid rangelands (Westoby et al. 1989). It is argued that pastoralist coping strategies to deal with climate variability, land tenure and access issues are more important than stocking rates in preventing land degradation (Derry and Boone 2010). These findings indicate that application of the carrying capacity concept is not capable of preventing desertification in extensive pasture, even under equilibrium conditions. The spatial dynamics of the interaction between animal behaviour and vegetation are non-linear and the distribution of grazing pressure is more important than total grazing pressure, which has only a limited influence on degradation (Okayasu et al. 2010). Therefore, explicit management of the spatial distribution of animals is essential to prevent land degradation and desertification in extensively grazed rangelands. Recently, researchers have shown in different parts of the world that livestock have little impact on forage resources (Fernandez-Gimenez and Allen-Diaz 1999; Sullivan and Rohde 2002; Lind et al. 2003) and so are not considered the main cause of degradation of rangeland and consequently desertification (Dean et al. 1995; Sefe et al. 1996; Okayasu et al. 2010). This is explained because high levels of climatic variability with peak droughts cause crashes in the animal populations, causing higher mortality rates in livestock and as a result overgrazing is halted before the desertification process is triggered (Derry and Boone 2010). This is only the case when animals are not provided with supplementary food during periods of food shortage. In addition, herbivores and herds tend to respond opportunistically to climate changes in rangelands (Ellis et al. 1993). They exploit the vegetation during production peaks and move to other areas when drought arrives, when there is opportunity for doing so.

Characteristics of grazing land: Crete and Asterousia

2012-06-12T12:09:23+00:00

Author: Constantinos Kosmas

{xtypo_alert}Editor's note 12Jun2012: Text source D211-2.2{/xtypo_alert}

One of the study sites investigating LEDD in grazing land is the Asteroussia Mountains, located in the island of Crete. Crete is the largest island in Greece (Figure 1) and is highly affected by land degradation and desertification. Domestic livestock production has been carried out since Neolithic times; about 10,000 years BP in Greece. Livestock became part of the environment affecting plant communities, ecosystems and landscapes. Grazing land in Greece covers an area of 5,300,000 hectares or 44 percent of the Greek territory (Zervas 1998; Sarlis 1998). Even though grazing land is affected by serious degradation problems and plant productivity is in decline, grazing contributes significantly to the economy of the country. Grazing land is found at a wide range of altitudes from lowlands to alpine in the following zones: (a) the lowland zone with altitude 0-600 m, (b) the middle zone with altitude 600-800 m, and (c) upper zone with altitude >800m (Polyzos 1991; Sarlis 1998). The upper zone covers 50 percent of the total area of pastures, producing 53 percent of the total palatable biomass. The middle and low zones cover 32 percent and 18 percent of the total grazing land respectively, producing 33 percent and 18 percent of the total biomass (Zervas 1998).

Figure 1. Location of Crete within Greece. Source: (Author C. Kosmas)

The ‘grazing areas’ of Greece (Figure 2) are covered on average by grass (32 percent); shrubs (15 percent); shrubs and forest with grass under storey (27 percent); and forest with grass under storey (26 percent) (Zervas 1998). According to this classification, 58 percent of this area is suitable for sheep and cattle grazing, while the remaining 42 percent is better suited to goat species. Grasslands in Greece are composed mainly of annual species (Zervas 1998). Pastures comprise a diversity of plant species, which is sustained by high grazing pressure for relatively short periods. Species counts are high, although there is considerable variation depending on soil fertility and grazing pressure. Swards may include species such as Avena sativa, Festuca arundinacaea, Trifolium spp., Hordeum spp., Medicago hispida, Vicia spp., and less commonly species such as Bromus catharicus, Dactylon cynodon, Dactylis glomerata, Haynaldia villosa and Securigera securodata. Wooded pastures dominated by shrubs and trees may include species such as OIea sp., Pistacia lentiscus, Arbutus undero, Quercus spp., Phillyra spp.,and Medicago arborea.

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Figure 2. Grazing land distribution in Greece (including forests which are mainly grazed). Source: (CORINE 2000 data)

Concerning land tenure, 83 percent of grazing land is state-owned or communal, and only 7.5 percent is under private ownership (Natsis 1985). Furthermore, 80 percent of forests are grazed annually, while the rest of the land (20 percent) is under protection from grazing. Dense high forests are not considered as grazing land although they may also be used for grazing (Papanastasis and Kontsiotou 1994). Of the total agricultural production of Greece, 70.3 percent derives from crop production and the remaining 29.7 percent from livestock production (Kaldis and Galanopoulos 2002).

Grazing land is found in all climatic zones in Greece, despite conditions being characterized as unfavorable for high grass production. The long duration of drought in the summer and low winter temperatures restrict plant growth. Therefore, natural pastures can be used for grazing for a short period during winter, spring or autumn but never throughout the whole year. Pastures are found in the following areas and climatic zones of Greece:

The mountainous, alpine climate zone. This includes the Pindos mountain chain which, running in a NNW-SSE direction, separates the country into two parts with different climatic characteristics, especially regarding rainfall.
The continental zone of north Greece including the mainland of Epirus, Macedonia, Thrace, and a large part of Thessaly, which has a climate changing gradually from characteristic Mediterranean to the colder climate of central Europe.
The marine Mediterranean Ionian zone including the coastal regions of western Greece and the Ionian islands.
The Mediterranean mainland zone including the southeastern part of Greece (Aegean) up to Thessaly and the Aegean islands. The climate of this region is similar to the marine Mediterranean but with lower winter temperatures and longer summer droughts.

The amount of rainfall ranges (from 780 to 1,280 mm per year) in the western part of Greece, this amount being reduced by about half in the eastern part, ranging from 380 to 640 mm per year. As far as temperature is concerned, grazing land is found between the isotherms of 14.5°C and 19.5°C. During the cold period, temperatures increase with decreasing latitude, whereas in the warm period, and especially between May and August, temperature increases from the coast to the mainland and particularly on the plains.

Grazing land in Greece is found on a wide variety of soils, usually too poor to support adequate biomass production. Soils on the lowlands are usually deep (depth >150 cm), well drained, medium to fine-textured, free of or rich in carbonates, with low organic matter content (usually lower than 2.8 percent in the surface horizon), formed mainly on alluvial deposits, and classified as Fluvisols, Cambisols and Luvisols. Soils in sloping areas are usually shallow (depth 10-50 cm), well drained, medium to fine-textured, low or rich in carbonates (depending on parent material), low in organic matter content (lower than 1.8 percent), formed mainly on marl, shale, conglomerates, limestone, flysch, and classified as Cambisols, Regosols, and Luvisols. Limestone is one of the main parent materials on which pastures exist with a high degree of soil degradation. Flysch is another important parent material on which soils have higher productivity than soils formed on limestone. Concerning topography, grazing lands are found in a variety of physiographic conditions. In most cases they are located on moderately sloping (6-12 percent), strongly sloping (12-18 percent), steep (18-35 percent) and on very steeply sloping (>35 percent) areas. Slopes are usually greater in the upper zone (altitude >800 m).

The ruminant production system, dominated by sheep and goats, may be intensive or extensive. The intensive system is the most common for cattle with more than 80 percent of the total raised in barns or sheds, the rest left out to graze. In the case of sheep and goats, three main pastoral systems exist (Papanastasis 1990):

Domestic or house system where a few animals per family are kept in barns to produce milk and meat. Feeding is with hay and concentrates the whole year round.
Village or flock system in which animals are put out to graze on rangelands during the day and brought in overnight.
Transhumance or nomadic system, with migration between lowlands in winter and highlands in summer.

Village and transhumance systems are the most common in Greece and are classified as extensive. Transhumance grazing systems operate at a variety of spatial and temporal scales and degrees of complexity. Animals may be moved daily from hills to valleys, or seasonally to the mountains for summer grazing. The high stocking rates, pastoral techniques and frequent fires have led to a significant decline of pasture quality and productivity, and an increase in the proportion of unpalatable plant species.

Grazing land in the lower zone is mainly used during the winter period or throughout the year. As a result of relatively favorable air temperatures, grass production is mainly dependent on rainfall. Grass production is greater in spring than in autumn but, due to lack of water, plants dry quickly and animals move to upper elevations. Pastures in the middle zone (600-800 m) are grazed mainly by goats throughout the whole year. Grass production in the middle zone is especially high during spring, while grazing can be limited for some periods during winter due to the presence of snow. Grazing land in the upper altitude zone receives large numbers of animals during the summer period, but is usually under-grazed due to a lack of infrastructure (roads and drinking water for the animals).

Grazing land is widespread throughout the island of Crete, covering 166,404 ha or 20.1 percent of the total area (CORINE 2000) (Figure 3). Grazing land in Crete is mainly found in hilly and mountainous areas under a variety of climatic and soil conditions. The long duration of drought in summer and the low temperatures prevailing during winter restricts plant growth. Therefore, natural pastures can be used for grazing for short periods during winter, spring or autumn but are not suitable for year-round grazing. Soils are usually shallow, formed mainly on limetone, marl, shale and flysch parent material, and are highly degraded due to soil erosion.

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Figure 3. Geographical distribution of natural pastures in Crete study site. Source: (CORINE 2000 data)

The number of sheep and goats on the island has almost doubled in the last three decades (Figures 4 and 5), while the number of cows has decreased (Greek Agricultural Statistical Service 2001). Livestock husbandry is a traditional activity which has shaped the mountains of Crete since the Neolithic period (Lyrintzis and Papanastasis 1995). However, in the last few decades the number of grazing animals has increased dramatically, mainly due to EU subsidies since 1981, when Greece became a member of the European Union. Based on national statistics (Greek Agricultural Statistical Service 2001), the numbers of sheep have increased five-fold and the number of goats doubled between 1961 and 1991. These high numbers have resulted in average stocking rates of 4.6 sheep-equivalents/ha/year (Menjli 1994), which is at least four times higher than the grazing capacity of rangelands (Papanastasis et al. 1990).

{tip }{/tip}	Figure 4. Change in animal populations in Greece during the last decades. Source: (Greek Agricultural Statistical Service 2001)
	Figure 5. Change in animal population in Crete during the last decades. Source: (Greek Agricultural Statistical Service 2001)

Shepherds periodically damage the natural vegetation deliberately by setting fires to eradicate the woody vegetation and encourage the growth of palatable grass, which is then overgrazed. The occurrence of a fire may temporarily increase the productivity of the land. After fire some species regenerate rapidly, creating favorable conditions for grazing. Studies conducted in eastern Crete have shown that the number of plant species, herbs and grasses, almost doubled after fire, while the number of shrubs and trees decreased. The first year after fire was very crucial for erosion, as the soil was relatively bare (Grove and Rackham 1996).

Characteristics of grazing land: Spain and Central Pyrenees

2012-06-12T12:53:02+00:00

Authors: Conceptión Alados, Erea Paz, Frederico Filliat, Maite Gartzia

{xtypo_alert}Editor's note 12Jun2012: Text source D211-2.4{/xtypo_alert}

Grasslands (land covered with herbaceous plants with less than 10 percent of tree and shrub cover, according to UNESCO) (Suttie et al. 2005), occupy around 13 percent of the land surface of Spain (Fillat et al. 2008). Livestock production has been an important activity in Spain since the Middle Ages. In particular, the production of quality wool played a key role in the development of Spanish socio-cultural heritage (Pinilla 1995). The grazing system was based on extensive exploitation of land, mainly through transhumance activity, which allowed the optimum use of pastures (Rebollo and Gomez-Sal 1998).

Pyrenean mountain ecosystems consist of diverse resources, and optimum production varies temporally along the altitudinal gradient (Garcia-Ruiz 1996) (Figure 1). The upper part of the mountains were used for grazing activities, leaving the lower part for agriculture. For example in the Borau valley, 73 percent of land use above 1700m was dedicated to extensive grazing, meanwhile 73 percent of land between 800m and 1300m was dedicated to agriculture (Vicente-Serrano 2001). During summer (July to October) abundant fodder is available, but in winter, fodder production is very limited. This is the basis for Pyrenean transhumance (Puigdefábregas and Balcells 1966), where livestock is moved to the Ebro depression during fodder shortages in winter time.

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Figure 1. Location of the Central Pyrenees study site. Source: (Figure produced by the author, C. Alados)

At lower altitudes, farming activities were mainly focused on the production of wheat, which reached its maximum extent at the end of the 19th century, with almost 28 percent of the land below 1,600m being cultivated (García-Ruiz et al. 1996). This was also the period with the highest population density in the Pyrenees. Almost all land was occupied, even land with very difficult topographic conditions. The better land, close to settlements, was improved with fertilizers, and stone walls were built on slopes to form flat terraces. Society was characterised by dense human population, living in big families with strong social cohesion. The traditional activity in the area consisted of grazing, frequent wildfires and rain-fed farming. Those activities resulted in important soil erosion in hill-slopes (García-Ruiz et al. 1996).

At the beginning of the 20th century, between 1905 and 1920, new roads were built to connect mountain communities to the valley floors (Pujadas and Comas 1975). The new roads irrevocably changed what had been self-sustaining communities, which had, up to that point, been able to provide most of the resources needed. As a result of the new transport links, food was imported into these valleys from elsewhere, resulting in the loss of competitiveness of mountain products and the subsequent abandonment of this traditional way of rural life (Puigdefábregas and Balcells 1970).

In the Pyrenees, grasslands are subalpine pastures that have replaced native forests, and have been grazed continuously for at least the last 500 years (Montserrat and Fillat 1990). One third of the Pyrenees flora is associated with grasslands. Reconstruction of past climate and vegetation since the Last Glacial Maximum (LGM) in the Pyrenees has revealed a widespread deforestation processes caused by forest fires around 3300 BP, probably related to the expansion of domestic livestock farming (García-Ruiz et al. 2001). With the exception of a few annuals that predominate in the gaps created by natural erosion or animal disturbances, most of the plants in the pastures are perennial grasses and forbs that reproduce clonally. In Spain, as in Western Europe, grassland communities are maintained by repeated physical disturbances of shrubs and trees and management activities such as fire and grazing for maintaining pastures and preventing plant succession in subalpine ecosystems (Ellenberg 1988b; García-Ruiz and Valero-Garcés 1998). These landscape structures created by human intervention have been maintained by herbivores and lead to plant-animal interactions in which each species has a particular role. These vegetation communities were adapted to the traditional methods of agricultural production which have now died out.

Characteristics of grazing land: Timahdit

2012-06-12T12:33:19+00:00

Author: Ahmed El Aich

{xtypo_alert}Editor's note 12Jun2012: Text source D211-2.3{/xtypo_alert}

The central northern part of the Middle Atlas is the home of the Beni Mguild Berbers. Fifty years, ago, they used a pattern of transhumance grazing. In the summer the sheep used to be pastured on the highlands, in the winter on the lowlands. Their main activity is sheep herding. Because of these seasonal movements they lived in tents. In addition to tents they also had houses, made of stones, loam and wood in which agricultural equipment and grain were stored. The Beni Mguild is composed of three tribes (Irkaoulen, Ait Arfa du Guigou et Ait Abdi). The increase of the population coincided with an increase in land used for agriculture. Allocation of lowlands to agriculture reduced areas for grazing and resulted in breakdown of transhumance. Grazing pressure on the remaining pastures increased with the break down in the vertical migration. In the early eighties grazing pressure averaged three sheep per hectare pastureland while, according to calculations, only one sheep and a lamb should be allowed in every hectare. This fact increased grazing pressure on what was left of land for grazing. The breakdown in the vertical transhumance pattern stopped pastoralists from moving their herd between summer and winter pastures. As a consequence, they settled in the high summer grazing lands.