Super- and coinfection: filling the range

Journal ArticleHow many different strains of a disease can coexist in a single population of hosts? What effect do different mechanisms of coexistence have on the properties of diseases? The principle of competitive exclusion (Armstrong and McGehee 1980; Levin 1970) states that no more species can coexist in a system than the number of resources or limiting factors allow, which can be thought of, somewhat imprecisely, as stating that a single trade-off can support only a single species - the one that deals best with that trade-off

Agronomic Characterisation of Sewage Sludge: Residual Effects

The progressive implementation of the EU Urban Waste Water Treatment Directive 91/271/EEC is increasing the quantities of sewage sludge requiring disposal. Agronomic use of sewage sludge should be based on crop fertiliser requirements and heavy metals content. Sewage sludge fertiliser potential depends on the stabilisation treatments of sewage sludge: composting, anaerobic digestion, aerobic digestion or pelleting (EPA, 1994). The objective of this experiment was to evaluate the fertiliser effectiveness and residual effects of three types of sewage sludge treated in three different ways

Seasonal Variation of Crude Protein Content of Different Herbaceous, Shrub and Tree Species

Silvopastoralism is a sustainable way of land management that reduces fire risk due to the reduction of fuel under trees when plants are used as animal food. This is particularly important in areas like Galicia that have 16% of the fired area of Europe. Silvopastoral systems can contribute to environment conservation and provide feed for autochthonous breeds more adapted to mountain conditions, enhancing biodiversity conservation. In formation on seasonal changes in crude protein content of spontaneous species will indicate better management of pasture resources in mountain areas

Effect of Tree Species and Density on Pasture Production in Galicia, Spain

Galicia produces 50% of the forest products of Spain. Livestock production earns 62% of the income of the agrarian sector in Galicia. Afforestation has been very important in the last decade to such an extent that the area of forest and woodlands now covers 62% of Galicia. It is necessary to increase the rate of return on investments in planted forests in order to avoid rural depopulation through improvement of rural development and welfare. This paper reports on the effect of combining pastures with trees

Shading Effect on Production and Protein Concentration of \u3cem\u3eDactylis Glomerata\u3c/em\u3e and \u3cem\u3eAgrostis Tenuis\u3c/em\u3e

Silvopastoral systems make compatible livestock and timber production and provide important advantages from economic and ecological points of view (Sibbald, 1996). Around one million ha of new afforested areas promoted by the EU Common Agricultural Policy have been established in the last decade, that can be used as potential silvopastoral system areas. Pasture production is usually reduced in dense stands as trees grow up due to the light interception by the tree crown, but the radiation reaching the soil will depend on the tree type and this will affect herbaceous species composition and development. The aim of this work was to evaluate the shading effect (0 and 50 % of light interception) on pasture production and composition of monocultures of cocksfoot (Dactylis glomerata L. var. Artabro) and bent grass (Agrostis tenuis Sibth. cv Highland) in simulated conditions

Pasture Production After Sewage Sludge and Liming Application on Highlands in North West Spain

In recent years, a sewage sludge surplus has been created in the EU countries, due to the Urban Waste Water Treatment Directive 91/271/CEE. Therefore, it is necessary to find adequate disposal for these residues in accordance with EU policy. Organic matter and nutrient sewage sludge contain principally N, indicating that it could be used as fertiliser. The main risk of this residue is its heavy metal content, whose solubility is usually increased as soil pH declines. The objective of this experiment was to determine the effect of liming and sewage sludge application on pasture production in a silvopastoral system located on acid soi

Silvopastoral Systems: Analyses of an Alternative to Open Swards

Silvopasture is a sustainable land use management practiced in most continents in the world including parts of southern Europe, but is not broadly used in northern and western Europe. The importance of this practice has been recognised and the last draft of the EU regulation by the European Agricultural Fund for Rural Development (http://europa.eu.int/comm/agriculture/capreform/rurdevprop_en.pdf) includes specifically funding for establishment of agroforestry practices in Europe. This paper discusses the advantages of managing semi intensive grassland within a silvopastoral system from an ecological, productive and social point of view in the south, south-central and western countries of Europe

Modeling Pinus radiata D. Don growth and pasture production under different land uses and climate scenarios

Yield-SAFE is a biophysical model to predict long-term production according to light and water availability in agricultural, forest, and agroforestry systems. The Yield-SAFE model should be calibrated and validated for the highest number of tree species and crops to be used as a management tool that takes into account climate change. This study aimed to calibrate and validate the Yield-SAFE model for Pinus radiata D. Don and sown pasture (Dactylis glomerata L.) to estimate the production in (1) forest systems, (2) agricultural systems, and (3) silvopastoral systems established in Galicia (NW Spain) under different conditions of climate: (i) reference “current” climate from 1961 to 1990, (ii) climate from 2021 to 2050, and (iii) climate from 2051 to 2080. The Yield-SAFE model can now be used to assess the long-term productivity of P. radiata D. Don and D. glomerata L. under different land uses and climate conditions. The Yield-SAFE model simulated similar tree and pasture growth in all scenarios of climate because the inter-annual variation of climate was small. However, tree growth estimated with the Yield-SAFE model was higher in the silvopastoral systems than in the forest systems, indicating that land use had more impact on land productivity than climate. Therefore, in regions such as Galicia, the Yield-SAFE model could be used as a tool to support the land use change in an agroforestry context, whilst also including climate scenarios which is considered a valuable solution to mitigate the effect of climate change

Analysis of a silvopastoral system with animals of the autochtonous swine breed Porco Celta in Galicia (NW Spain)

PosterPig traditional production systems in Galicia (NW Spain) are based on seasonal resources us like chestnut and pastures. The Breeders' Association of the autochthonous Celtic breed of pigs (ASOPORCEL) has developed a novel system within the traditional Galicia grazed forest areas in order to preserve landscape quality and biologic diversity, minimizing therefore the environmental impact of pig production. One of the main concerns of silvopastoral system implementation is the need of fencing. Fencing costs could be reduced if animals are rearing with infrastructures based on Pavlov animal condition reflex management in an extensive system. Therefore, cost reduction is obtained thanks to the clear reduction of personnel needs to feed animals, fencing costs and understorey clearance to reduce forest fires. In 2013 an experiment was carried out in Nebra (NW of Spain) in a young Pinus pinaster plantation. Pig stocking rate was around 3.85 pigs per ha (25 males and 25 females) in a total surface of 13 ha. Forest grazing program was initiated when animals were three months old in March 2013 and finished in December 2013. They were allowed access the whole plot. Concentrate was provided twice every day after sounding an alarm to attract pigs. All the animals adapted rapidly to the system. Two types o understory vegetation (Ulex and Pteridium) was sampled following a transect from close to far away feeding areas (three distances). Fern control was intense, being gorse less consumed. After nine months, average animal daily gain (ADG) obtained was 290 ± 4 gr. We can conclude that the used method is perfectly adaptable to the systems of exploitation suggested for the Celtic pig breed. This will be highly relevant to preserve this autochthonous breed and increase the number of extensive farms in the area while contributing to fix population dedicated to use silvopastoral systems