Suchergebnisse

In the European Union, the majority of afforestation is carried out on former agricultural land. This afforestation causes fundamental changes in ecosystem structure and functioning, with the trees intercepting light and precipitation, producing litterfall and competing for soil nutrients. All of these effects could potentially have a negative impact on understorey biomass and vascular plant biodiversity in a relatively short time span. This study aims to evaluate the effects of afforestation with Pinus radiata D. Don (Monterey pine: pine) and Betula pubescens Ehrh. (Downy birch: birch), established at two different densities (2500 and 833 trees ha21) and sown with two different pasture mixtures (Dactylis glomerata L. + Trifolium repens L. + Trifolium pratense L. and Lolium perenne L. + T. repens L. + T. pratense L.), on understorey biomass, alpha plant biodiversity, life cycle type (annuals vs. perennials) and beta biodiversity over a period of 11 years. Pine showed better development than birch throughout the study, although both species were very sensitive to tree density. While increasing density increased pine height and decreased pine diameter, both aspects of birch development were reduced by higher tree densities. Aboveground biomass increased throughout the study. Alpha plant biodiversity was drastically reduced under pine established at high density, 11 years after afforestation. However, the similarities in species richness, species composition and the low beta growth rates found under pine at low density, and birch at both high and low density suggest that, in these cases, the choice of canopy tree has little consequence for understorey biodiversity at this stage of system development.

In the European Union, the majority of afforestation is carried out on former agricultural land. This afforestation causes fundamental changes in ecosystem structure and functioning, with the trees intercepting light and precipitation, producing litterfall and competing for soil nutrients. All of these effects could potentially have a negative impact on understorey biomass and vascular plant biodiversity in a relatively short time span. This study aims to evaluate the effects of afforestation with Pinus radiata D. Don (Monterey pine: pine) and Betula pubescens Ehrh. (Downy birch: birch), established at two different densities (2500 and 833 trees ha21) and sown with two different pasture mixtures (Dactylis glomerata L. + Trifolium repens L. + Trifolium pratense L. and Lolium perenne L. + T. repens L. + T. pratense L.), on understorey biomass, alpha plant biodiversity, life cycle type (annuals vs. perennials) and beta biodiversity over a period of 11 years. Pine showed better development than birch throughout the study, although both species were very sensitive to tree density. While increasing density increased pine height and decreased pine diameter, both aspects of birch development were reduced by higher tree densities. Aboveground biomass increased throughout the study. Alpha plant biodiversity was drastically reduced under pine established at high density, 11 years after afforestation. However, the similarities in species richness, species composition and the low beta growth rates found under pine at low density, and birch at both high and low density suggest that, in these cases, the choice of canopy tree has little consequence for understorey biodiversity at this stage of system development. ; info:eu-repo/semantics/publishedVersion

The combination of tree and pasture production has been recently promoted by the European Union as an agroforestry system type. Pasture production under trees produces annual farm outputs which promote long term rural population stabilisation compared with exclusively forest systems. At the same time, the presence of a tree increases the long term value of the land. The objective of this study was to evaluate the effect of two different tree densities, seed mixtures and fertilization on annual meadow production after 9 years of a silvopastoral system. The tree species was birch (Betula alba L.) established at two densities (2500 and 833 tree ha–1). Fertilization regimes included no fertilization and mineral inputs. Initial seed mixtures included cocksfoot (Dactylis glomerata) and perennial ryegrass (Lolium perenne) together with white and red clover (Trifolium repens and T. pratense). The results showed a significant effect of fertilization, seed mixture and tree density on meadow production. Meadow production was not reduced over time in spite of tree canopy development, which makes birch more suitable for meadow production when compared with radiate pine (Pinus radiata). Fertilization had a major effect at the start of the experiment in terms of modifying annual meadow production. However, by the end of the experiment its effect was modified by tree density and previous seed mixture.

Silvopastoral systems are sustainable form of land management promoted by European Union. The productivity of the herbaceous and tree components in a silvopastoral system could be limited by soil fertility. The use of adequate doses of organic fertilisers like sewage sludge could enhance the productivity of both pasture and trees and promote biodiversity. The quantification of the best dose of sewage sludge to be applied in a silvopastoral system is important in order to enhance production and biodiversity in a silvopastoral system, while avoiding nitrate contamination of the ground water. This study aims to evaluate the effects of different doses of sewage sludge (100 kg total N ha−1, 200 kg total N ha−1 and 400 kg total N ha−1) on different variables of soil (soil pH, effective exchange capacity and the saturation percentage of Al, K, Ca, Mg and Na), tree growth and pasture (production, species richness and botanical composition) as compared to the fertilisation treatment in a silvopastoral system under Quercus rubra L. Sewage sludge applications initially improved soil nutrient levels (effective exchange capacity and Ca saturation percentage) and subsequently pasture production and tree growth when 200 and 400 kg of total N ha−1 were applied. On the other hand, the establishment of pasture and trees improved soil conditions at a medium term due to the organic matter input into the sandy soil, which increased species diversity specially at a 100 kg of total N ha−1 dose.

Agroforestry (AF) is the practice of deliberately integrating woody vegetation (trees or shrubs) with crop and/or animal systems to benefit from the resulting ecological and economic interactions. The appropriate application of AF practices is a key avenue to help the European Union to achieve more sustainable methods of food production. However, there is a lack of agroforestry knowledge among end-users. The project AFINET (AgroForestry Innovation NETworks) is a thematic network to foster knowledge exchange between scientists and practitioners on agroforestry. During the initial stage of the project, an assessment of positive (benefits) and negative aspects (limitations) on the implementation of AF systems was conducted among AFINET stakeholders in Galicia (north-west Spain). The reduction of fire risk, the enhancement of biodiversity and the improvement of landscape aesthetics values were perceived as the main benefits of implementing agroforestry by the stakeholders. On the other hand, the possibility of obtaining grants to establish AF systems was perceived as less important. When asked about the limitations, a lack of knowledge and professional advice were identified as the main barriers for the implementation of AF systems in the region, along with the risk of incompatibilities with the common agricultural policy (CAP).

Application of sewage sludge to agricultural soil is a common practice in the European Union (EU) because of low costs and recycling of nutrients achieved. The aim of this study was to evaluate the effects of different types (anaerobic, pelleted and composted sewage sludge) and application rates of sewage sludge on annual pasture production, botanical composition and species richness, compared with an unfertilized control treatment, in meadows established in Galicia (Spain). The results showed that annual pasture production was increased by anaerobic and pelleted sewage sludge in the first year of the study. However, no effects of treatments were found on botanical composition and species richness later in the study.

Increased forest area and wood production is a key goal for the European Union, together with avoidance of hazards that damage forests. Galicia is a region of northwest Spain that belongs to the Atlantic biogeographic region with very high wood production, but due to climate fire has a major negative impact on forest productivity (i.e. it represents 16% of the fires of Europe). Silvopastoral systems offer the potential to enhance forest productivity as well as to obtain income from newly afforested areas in the short term. Herbaceous pasture production within such systems can be optimized through species selection and through fertilization. The aim of the present study was to evaluate effect of three types of fertilization on two sward mixtures established under Pinus radiata D. Don cover on abandoned agricultural land over an initial period of 7 years. Tree and pasturegrowth were enhanced with organic fertilization, tree growth rate not being limited by summer drought, and compared with mineral treatment, trees growing up on sludge treatment had around 35 and 30% more height and diameter, espectively. Acidity tendency of Galician soils was reduced with mineral treatment. Soil pH was positively affected by mineral fertilization as it was reduced in less extent in this treatment (pH 6) than in organic (pH 5.3) or no fertilization treatment (pH 5.6), as crop cation extractions were reduced. The proportion of Na and Mg in the effective CEC was higher in fertilization with dairy sludge and no fertilization plots due to better tree canopy development. The interchangeable potassium content in ryegrass sown plots was reduced when no fertilization was applied due to dicot extractions, which can explain lower tree growth than in non-fertilized cocksfoot plots. Correct tree and pasture management, using appropriate sowing mixtures and fertilization types, makes it possible to improve the productivity of both components of the silvopastoral system. Our present results indicate that it is better to use organic fertilizers ...

Increased forest area and wood production is a key goal for the European Union, together with avoidance of hazards that damage forests. Galicia is a region of northwest Spain that belongs to the Atlantic biogeographic region with very high wood production, but due to climate fire has a major negative impact on forest productivity (i.e. it represents 16% of the fires of Europe). Silvopastoral systems offer the potential to enhance forest productivity as well as to obtain income from newly afforested areas in the short term. Herbaceous pasture production within such systems can be optimized through species selection and through fertilization. The aim of the present study was to evaluate effect of three types of fertilization on two sward mixtures established under Pinus radiata D. Don cover on abandoned agricultural land over an initial period of 7 years. Tree and pasture growth were enhanced with organic fertilization, tree growth rate not being limited by summer drought, and compared with mineral treatment, trees growing up on sludge treatment had around 35 and 30% more height and diameter, espectively. Acidity tendency of Galician soils was reduced with mineral treatment. Soil pH was positively affected by mineral fertilization as it was reduced in less extent in this treatment (pH 6) than in organic (pH 5.3) or no fertilization treatment (pH 5.6), as crop cation extractions were reduced. The proportion of Na and Mg in the effective CEC was higher in fertilization with dairy sludge and no fertilization plots due to better tree canopy development. The interchangeable potassium content in ryegrass sown plots was reduced when no fertilization was applied due to dicot extractions, which can explain lower tree growth than in non-fertilized cocksfoot plots. Correct tree and pasture management, using appropriate sowing mixtures and fertilization types, makes it possible to improve the productivity of both components of the silvopastoral system. Our present results indicate that it is better to use organic fertilizers ...

Silvopastoral systems are ancient farming systems in the world, consisting of the combination of a woody component (trees or shrubs) and crops and/or animals within the same land-management unit. In various European Union (EU) countries, the possibility of using sewage sludge as a fertilizer is under consideration as a viable method of disposal, considering the increase in sewage-sludge production in recent years and the restrictions imposed by European policy on the usual methods of disposal. The concern is the concentration of heavy metals, which can reach humans through the food chain. In Spain, R.D. 1310/1990, as well as European Directive 86/278, limit the total in-soil heavy-metal concentration, but not the solubility changes, which directly affect plant absorption and leaching of heavy metals throughout the soil profile. The objective of this experiment was to compare, in a silvopastoral system over a period of 3 years, the effect of applying three doses of sewage sludge combined with and without liming, on total and available soil Zn and Cu and their concentration in plants. Liming did not affectct Zn and Cu availability; however, sewage sludge increased Zn and Cu availability, though total in-soil Zn was increased only in November 2000. In-plant Zn concentration was increased by sewage sludge in the last 2 years of the study. In all cases, the quality of forage obtained and measured with regard to the concentrations of Zn and Cu was adequate for animal consumption. With respect to sewage-sludge application as a fertilizer, the management of heavy-metal availability must be included in the policy, because environmental risk could then be adequately evaluated.

Horse grazing systems may affect productivity and biodiversity of understory developed under Pinus radiata D. Don silvopastoral systems, while acting as a tool to reduce the risk of fire. This study compared continuous and rotational grazing systems effect upon biomass, fractions of stem, sprouts, leaves and woody parts of Ulex europaeus L. and alpha (Species Richness, Shannon-Wiener) and beta (Jaccard and Magurran) biodiversity for a period of four years in a P. radiata silvopastoral system. The experiment consisted of a randomized block design of two treatments (continuous and rotational grazing). Biomass, and species abundances were measured - biodiversity metrics were calculated based on these results for a two years of grazing and two years of post-grazing periods. Both continuous and rotational grazing systems were useful tools for reducing biomass and, therefore, fire risk. The rotational grazing system caused damage to the U. europaeus shrub, limiting its recovery once grazing was stopped. However, the more intensive grazing of U. europaeus plants under rotational had a positive effect on both alpha and beta biodiversity indexes due to the low capacity of food selection in the whole plot rather than continuous grazing systems. Biomass was not affected by the grazing system; however the rotational grazing system is more appropriate to reduce U. europaeus biomass and therefore forest fire risk at a long term and to enhance pasture biodiversity than the continuous grazing system ; This research was funded by the CICYT and by the Rural Development Galician Government (Xunta de Galicia) ; SI