GenMNT : un outil simple pour la génération de modèles numériques de terrains

For landscape modelling and simulations, the use of a digital elevation model is absolutely necessary. However, the purchase of such a model is not always possible for the expected localization and precision. We developed a very simple software allowing to build digital elevation models from altitude measurements taken on the terrain.The aim of this article is to describe the GenMNT software freely distributed on the Cybergeo web site. The user manual comes with a quick and non-exhaustive presentation of the main methods of interpolation. The running of our program (based on the Delaunay triangulation) is described step by step. Lastly, we insist on the software’s simplicity and its interfacing with the Vistapro software to produce landscape 3D realistic views

Simulations spatialisées des pullulations de campagnols terrestres : Etude de l'influence des structures paysagères

For more than 30 years we have been periodically observing multiannual outbreaks of grassland rodents, Arvicola terrestris Sherman, in Auvergne (France). This phenomenon is more and more frequent and heavy despite chemical treatment. That’s why we study the relationships between water voles and their predators within landscape and farming practices. In order to test different situations of landscape organization, we develop a simulator which will enable us to quantify the evolution of predator and vole populations. This simulator uses a spatial model based on cellular automata. Instead of the classical approach of population dynamics, we have chosen cellular automata. This technique enables us to perform spatial simulations. Simple rules apply on wide number of elements. These local and individual interactions determine complex behaviors of the system at the global level. Nowadays, high computer speeds enable this kind of approach. Maps of land use, maps of vole densities and number of various predators are the input variables of the model. Several parameters enable us to tune constitutive rules of our model (movement and reproduction of voles, hunt territory and predation, evolution of predator density, …). Outputs: for each iteration, the simulator creates maps of vole densities and calculates the number of each species. One iteration represents one year. The first results which are obtained on a real territory (municipalities of Ceyssat and Olby in the department of Puy-de-Dôme) are encouraging. We hope that our simulator (when it will be tuned and validated) will enable us to carry out a wide number of “virtual” experiments that are unfeasible in the “real” world

Modelisation of work organisation of livestock farms to simulate changes

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Simulation de stratégies de gestion du système fourrager prenant en considération la diversité inter parcelle à l'échelle de l'exploitation : cas d'élevages laitiers en Auvergne

International audienceLand diversity is a characteristic of low-input farming systems. Land diversity can refer to between-field diversity of grassland vegetation types that are a result of management practices (fertilisation, grazing, cutting), and environmental factors (altitude, aspect, soil water capacity) that have an influence on herbage production. Land diversity can also concern other characteristics of the field, like its distance to the cowshed or its suitability for mechanization for hay-making that are key characteristics affecting the spatial organization of management practices. The purpose of this study was to evaluate, using a simulation model, the consequences for yield of taking the land diversity at farm level into account in the decision-making process. We made the assumption that it could be an asset rather than a constraint for the management of the forage system, and that it could lead to an improvement in the forage balance in dairy farming systems. The model is able to simulate the decision-making process in managing this diversity during a growing season. The decision process was translated into three management strategies of the forage system representing increasing consideration of the farmland diversity. We then simulated these three strategies for two weather series and two farmland diversity levels. We noticed that the strategy giving the most consideration to the farmland diversity improves the forage self-sufficiency (due to higher yields and quality of forage supplies, and a decrease in the amount of hay fed during the grazing period). We thus concluded that the management of between-field diversity could be an asset for extensive farming systems. In the context of extensification of agriculture and increasing concern about its environmental impact on biodiversity, this approach must be pursued. The oriented-object structure of the model will facilitate improvements

Batchman : outil informatique de représentation graphique des pratiques d'allotement dans les élevages de ruminants. Batchman: a software for graphical representations of batching practices in ruminant farming systems

International audienc

Simulation of forage management strategies considering farm-level land diversity : Example of dairy farms in the Auvergne

International audienceLand diversity is a characteristic of low-input farming systems. Land diversity can refer to between-field diversity of grassland vegetation types that are a result of management practices (fertilisation, grazing, cutting), and environmental factors (altitude, aspect, soil water capacity) that have an influence on herbage production. Land diversity can also concern other characteristics of the field, like its distance to the cowshed or its suitability for mechanization for hay-making that are key characteristics affecting the spatial organization of management practices. The purpose of this study was to evaluate, using a simulation model, the consequences for yield of taking the land diversity at farm level into account in the decision-making process. We made the assumption that it could be an asset rather than a constraint for the management of the forage system, and that it could lead to an improvement in the forage balance in dairy farming systems. The model is able to simulate the decision-making process in managing this diversity during a growing season. The decision process was translated into three management strategies of the forage system representing increasing consideration of the farmland diversity. We then simulated these three strategies for two weather series and two farmland diversity levels. We noticed that the strategy giving the most consideration to the farmland diversity improves the forage self-sufficiency (due to higher yields and quality of forage supplies, and a decrease in the amount of hay fed during the grazing period). We thus concluded that the management of between-field diversity could be an asset for extensive farming systems. In the context of extensification of agriculture and increasing concern about its environmental impact on biodiversity, this approach must be pursued. The oriented-object structure of the model will facilitate improvements

Batchman : outil informatique de représentation graphique des pratiques d’allotement dans les élevages de ruminants

National audienc