Browsing by Author "Herzog, F."
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Item Open Access Development and application of bio-economic modelling to compare silvoarable, arable, and forestry systems in three European countries.(Elsevier Science B.V., Amsterdam., 2007-04-01T00:00:00Z) Graves, Anil R.; Burgess, Paul J.; Palma, João H. N.; Herzog, F.; Moreno, G.; Bertomeu, M.; Dupraz, Christian; Liagre, F.; Keesman, Karel; van der Werf, Wopke; Koeffeman, de Nooy A.; van den Briel, J. P.Silvoarable agroforestry could promote use of trees on farms in Europe, but its likely effect on production, farm profitability, and environmental services is poorly understood. Hence, from 2001 to 2005, the Silvoarable Agroforestry for Europe project developed a systematic process to evaluate the biophysical and economic performance of arable, forestry, and silvoarable systems in Spain, France, and The Netherlands. A biophysical model called “Yield-SAFE” was developed to predict long-term yields for the different systems and local statistics and expert opinion were used to derive their revenue, costs, and pre- and post-2005 grant regimes. These data were then used in an economic model called “Farm-SAFE” to predict plot- and farm-scale profitability. Land equivalent ratios were greater than one, showing Yield-SAFE predicted that growing trees and crops in silvoarable systems was more productive than growing them separately. Pre-2005 grants in Spain and The Netherlands penalised silvoarable systems, but post-2005 grants were more equitable. In France, walnut and poplar silvoarable systems were consistently the most profitable system under both grant regimes. In Spain, holm oak and stone pine silvoarable systems were the least profitable system under pre-2005 grants, but only marginally less profitable than arable systems under post-2005 grants. In The Netherlands, low timber values and the opportunity cost of losing arable land for slurry manure application made silvoarable and forestry systems uncompetitive with arable systems under both grantItem Open Access Farm-SAFE: The process of developing a plot- and farm-scale model of arable, forestry, and silvoarable economics(Springer Science Business Media, 2011-02-01T00:00:00Z) Graves, Anil R.; Burgess, Paul J.; Liagre, F.; Terreaux, J.-P.; Borrel, T.; Dupraz, Christian; Palma, João H. N.; Herzog, F.Financial feasibility and financial return are two key issues that farmers and land owners consider when deciding between alternative land uses such as arable farming, forestry and agroforestry. Moreover regional variations in yields, prices and government grants mean that the relative revenue and cost of such systems can vary substantially within Europe. To aid our understanding of these variations, the European Commission sponsored a research project called “Silvoarable Agroforestry For Europe” (SAFE). This paper describes the process of developing a new economic model within that project. The initial stages included establishing criteria for the model with end-users and reviewing the literature and existing models. This indicated that the economic model needed to allow comparison of arable farming, forestry and agroforestry systems at a plot- and a farm-scale. The form of comparisons included net margins, net present values, infinite net present values, equivalent annual values, and labour requirements. It was decided that the model would operate in a spreadsheet format, and the effect of phased planting patterns would be included at a farm- scale. Following initial development, additional user feedback led to a final choice on a model name, a final method of collating input data, and the inclusion of field-based operations such as varying the cropped area, replacing dead trees, and pruning. In addition options in terms of improved graphical outputs and the ability to undertake sensitivity analysis were developed. Some of the key lessons learnt include the need to establish clear model criteria and the benefits of developing a working prototype at an early stage to gain user- feedbItem Open Access Implementation and calibration of the parameter-sparse Yield-SAFE model to predict production and land equivalent ratio in mixed tree and crop systems under two contrasting production situations in Europe(Elsevier Science B.V., Amsterdam., 2010-07-10T00:00:00Z) Graves, Anil R.; Burgess, Paul J.; Palma, João H. N.; Keesman, K. J.; van der Werf, Wopke; Dupraz, Christian; van Keulen, Herman; Herzog, F.; Mayus, MartinaSilvoarable agroforestry, the integration of trees and arable crops on the same area, has the potential to offer production, ecological, and societal benefits. However, the uptake of such systems in Europe has been limited by a combination of unsupportive policies and uncertainty concerning their productivity, profitability, and environmental impact. Faced with a lack of experimental data, the parameter-sparse Yield-SAFE model offers one method for generating plausible yield data and improving understanding of production in mixed tree–crop systems under European conditions. The applicability of the model was examined by: (i) selecting two contrasting sites in France and the UK with measured agricultural, silvoarable and/or forestry data, (ii) implementing the model in a software package, and (iii) inputting data and parameters on the climate, soils, management regime, and tree and crop types. Following calibration, Yield-SAFE provided credible descriptions of measured arable and tree (Populus spp.) yields in the monoculture and silvoarable systems at the two sites. An examination of the response of the model to changes in model parameters and environmental and management data showed that silvoarable crop yields were most sensitive to variations in tree parameters. Increased soil depths increased timber yields, and increasing stand density increased stand volume whilst decreasing individual tree volume. In all the simulations, the model predicted greater efficiency in use of land, i.e. greater land equivalent ratios, when trees and crops were combined rather than grown as sole crops. These results, supported by the sparse experimental data available, indicate that agroforestry provides a method of increasing food, timber and biomass production from limited land resources in EuropItem Open Access Methodological approach for the assessment of environmental effects of agroforestry at the landscape scale.(Elsevier Science B.V., Amsterdam., 2007-04-01T00:00:00Z) Palma, João H. N.; Graves, Anil R.; Burgess, Paul J.; Keesman, K. J.; van Keulen, Herman; Mayus, Martina; Reisner, Y.; Herzog, F.Silvoarable agroforestry, the deliberate combined use of trees and arable crops on the same area of land, has been proposed in order to improve the environmental performance of agricultural systems in Europe. Based on existing models and algorithms, we developed a method to predict the environmental effects of SAF at a farm and landscape scale. The method is comprised of an assessment of soil erosion, nitrogen leaching, carbon sequestration, and landscape diversity and allowed the comparison of the environmental performance of SAF with arable systems using these four indicators.Item Open Access Modeling environmental benefits of silvoarable agroforestry in Europe.(Elsevier Science B.V., Amsterdam., 2007-03-01T00:00:00Z) Palma, João H. N.; Graves, Anil R.; Bunce, R. G. H.; Burgess, Paul J.; de Filippi, R.; Keesman, K. J.; van Keulen, Herman; Liagre, F.; Mayus, Martina; Moreno, G.; Reisner, Y.; Herzog, F.Increased adoption of silvoarable agroforestry (SAF) systems in Europe, by integrating trees and arable crops on the same land, could offer a range of environmental benefits compared with conventional agricultural systems. Soil erosion, nitrogen leaching, carbon sequestration and landscape biodiversity were chosen as indicators to assess a stratified random sample of 19 landscape test sites in the Mediterranean and Atlantic regions of Europe. At each site, the effect of introducing agroforestry was examined at plot-scale by simulating the growth of one of five tree species (hybrid walnut Juglans spp., wild cherry Prunus avium L., poplar Populus spp., holm oak Quercus ilex L. subsp. ilex and stone pine Pinus pinea L.) at two tree densities (50 and 113 trees ha−1) in combination with up to five crops (wheat Triticum spp., sunflower Helianthus annuus L., oilseed rape Brassica napus L., grain maize and silage maize Zea mays L.). At landscape-scale, the effect of introducing agroforestry on 10 or 50% of the agricultural area, on either the best or worst quality land, was examined. Across the 19 landscape test sites, SAF had a positive impact on the four indicators with the strongest effects when introduced on the best quality land. The computer simulations showed that SAF could significantly reduce erosion by up to 65% when combined with contouring practices at medium (>0.5 and <3 t ha−1 a−1) and high (>3 t ha−1 a−1) erosion sites. Nitrogen leaching could be reduced by up to 28% in areas where leaching is currently estimated high (>100 kg N h−1 a−1), but this was dependent on tree density. With agroforestry, predicted mean carbon sequestration through immobilization in trees, over a 60-year period, ranged from 0.1 to 3.0 t C h−1 a−1 (5–179 t C h−1) depending on tree species and location. Landscape biodiversity was increased by introducing SAF by an average factor of 2.6. The implications of this potential for environmental benefits at EuropeaItem Open Access Silvoarable agroforestry in Europe - systems for meeting food and industry crop requirements with improved resource-use efficiency(2009-05-12T00:00:00Z) Palma, João H. N.; Graves, Anil R.; Burgess, Paul J.; van der Werf, Wopke; Herzog, F.