Discriminating small wooded elements in rural landscape from aerial photography: a hybrid pixel/object-based analysis approach

While small, fragmented wooded elements do not represent a large surface area in agricultural landscape, their role in the sustainability of ecological processes is recognized widely. Unfortunately, landscape ecology studies suffer from the lack of methods for automatic detection of these elements. We propose a hybrid approach using both aerial photographs and ancillary data of coarser resolution to automatically discriminate small wooded elements. First, a spectral and textural analysis is performed to identify all the planted-tree areas in the digital photograph. Secondly, an object-orientated spatial analysis using the two data sources and including a multi-resolution segmentation is applied to distinguish between large and small woods, copses, hedgerows and scattered trees. The results show the usefulness of the hybrid approach and the prospects for future ecological applications

Transmissions de l’exploitation en moyenne montagne pyrénéenne : ruptures et continuités

Que transmet-on quand on transmet une exploitation agricole aujourd’hui? La pérennité des exploitations et la transmission intergénérationnelle sont au centre des enjeux du développement durable, en agriculture notamment (Landais, 1999

Micro-topography associated to forest edges

Forest edges are often defined as the discontinuity between the forest habitat and an adjacent open habitat, thus they are based on a clear difference in the structure of the dominant vegetation. However, beside this very general definition, in the field we can observe a large diversity of edges, with often different kinds of micro-topography features: bank, ditch, stone wall, path, etc. As these elements are rather common in many temperate forest edges, it seems important to start to characterize them more clearly and with consistency. From a set of observations in south-western France, we build a first typology of the micro-topographic elements associated to forest edges. For each of them we describe the process, natural or human induced, at their origin, and according to the literature available, we identify some of their key ecological roles. Banks, generated by the differential erosion between forest and crops along slopes, are especially analyzed since they are the most common micro-topographic element in our region. It offers many micro-habitat conditions in the soil used by a wide range of species, notably by several bee species. More research is required to study in details the importance of such micro-topographic elements

How do farmers' representations influence landscapes? A multi-scale approach combining mental models and forest monitoring in southwestern France

In Europe, rural forests have declined during the last decades, mainly because of the intensification of agriculture and the separation of forest and agricultural systems. But beyond global trends, little is known about small-scale dynamics and factors affecting rural forests. In the Long-Term Social-Ecological Research (LTSER) platform Vallées et Coteaux de Gascogne, we combined GIS monitoring, ethnographic investigations and mental models to understand rural forests dynamics and related anthropogenic factors

Atelier thématique: Conversion de rasters en vecteurs

Nous avons accès à des cartes thématiques diverses au format image, (cartes pédologiques par ex.). Celles-ci sont des sources d’information très intéressantes car elles permettraient si nous pouvions les importer, d’exploiter leurs données comme s’il s’agissait d’une couche vectorielle, et croiser leurs informations avec des mesures. Cependant, ces images sont très hétérogènes : aux formats variés (jpeg, pdf, etc.), souvent issues de scan (résolution, qualité), complexes (nombreuses classes d’objet) et sur des aires géographiques étendues (région, bassin versant, etc.). L’idée est donc de les vectoriser pour les reproduire à l’identique, mais dans un format plus exploitable. Il existe trois méthodes de difficulté et de chronophagie croissante : 1°) la vectorisation automatique ou conversion raster-vecteur ou polygonisation 2°) le dessin vectoriel ou digitalisation 3°) l’analyse d’image orientée-objet ou segmentation orientée obje

The influence of spatial and temporal discontinuities of forest habitats on the current presence of flightless saproxylic beetles

Flightless saproxylic beetles were selected in order to study the impact of temporal and spatial discontinuity of forests. They were chosen because: (1) they are unable to fly, making them dispersal-limited species, (2) they have a saproxylic diet, which means they are closely linked to the forest, and (3), they have rarely been studied. Forest temporal continuity was expected to be the main factor explaining the presence of these species, modulated by the past and present amount of forest in the surrounding landscape. Twenty-seven forests, distributed into three zones, were sampled in southwestern France. Flightless saproxylic beetles were surveyed using a Winkler extractor and a Berlese funnel. Their presence/absence were modelled using generalised linear mixed models, with zone variable as random effect. Two species showed significant zone effect and were only or more present in the zone with the highest present forest amount in a 0.5 km radius. In the model that converged, the only selected variable was the past amount of forest in the landscape. The size of the forest, the presence of dead wood and the forest temporal continuity were not included in this model. The importance of the amount of forest in the landscape supports the hypothesis that dispersal-limited species are affected by landscape characteristics. This study demonstrates an important link between the presence of Dienerella clathrata and the amount of forest in the past, which led to an indicator species analysis being performed

Les réseaux de correction différentielle

Cet article a pour principal objectif de répondre aux questions qui peuvent se poser au moment de la mise en place d’un dispositif de correction différentielle : pourquoi les réseaux de correction différentielle ? Quels sont-ils et où sont-ils ? Quel réseau couvre mon domaine expérimental ? Comment l’utiliser et avec quel matériel adapté ? Les systèmes satellitaires de navigation globaux (GNSS-global navigation satellite system-) présentent des sources d’erreur induisant de l’imprécision sur les calculs de géo-positionnement. Ces erreurs de calcul peuvent être particulièrement problématiques pour des dispositifs expérimentaux reposant sur le géo-positionnement d’un mobile en temps réel (mode RTK-real time kinematic-) appliqué par exemple à l’agriculture de précision. La solution pour améliorer significativement la précision du calcul consiste à utiliser des algorithmes correcteurs diffusés par des stations de mesure fixes ou faisant partie d’un réseau. Pour utiliser ces informations le mobile doit être capable de se connecter à la station (radio, Internet, téléphone, etc.), de charger et recalculer rapidement la géolocalisation pratiquement en temps réel. Parmi les réseaux de stations disponibles, il en existe des publics (RGP-réseau GNSS permanent-) et des privés (Teria, Sat-info, Orphéon) qui seront détaillés et comparés. Un premier tableau récapitulant les sites expérimentaux de l’INRA équipés et les couvertures des réseaux est présenté dans cet article pour partager les informations avec les Unités expérimentales

Assessment of agricultural land-use change for helping sustainable land management and landscape development

Agriculture is nowadays expected to adopt “multifunctional” land use practice as a contribution to sustainable development of rural areas. We started a participatory research study in the Coteaux de Gascogne (France) to prospect local paths for agricultural systems contribution to landuse sustainability. The area considered is a study-site of the Long term Ecosystem Research network.Our first common objective is to understand how family-farm dynamics contribute to land-use change at the landscape level. We started therefore a spatially-explicit and exhaustive study of agricultural land use and its change since the 1950s at a reference area of limited size (4 villages). The method consists in survey at every farmer using land in the area using both a semi-directive questionnaire and farmland maps and the building up of a Geographic Information System (GIS). We present here the first results of our assessment of the variety in family-farms and their land use practice (56 farms). We discuss our perspectives for using these results and helping local land use development

Assessing land cover changes in the French Pyrenees since the 1940s A semi‐automatic GEOBIA approach using aerial photographs

International audienceAgro-pastoral landscapes of the Pyrenees are subject to fast spontaneous reforestation. The objective of this work is to assess the spatial patterns of land cover changes during the last 70 years in three study sites of the Pyrenees, and to compare the local dynamics in order to observe and to explain similarities and disparities

Efecto de diferentes tiempos y temperaturas de congelación y deshidratación en la rehidratación de arroz (Oryza sativa L.) instantáneo para microondas

This work aimed to study the effects of different treatments (time and temperature) for instant rice consumption for the Ecuadorian market. This is because at present consumption and demand for pre-finished products that are quick to prepare and easy to eat have had a great growth. To determine the best process for developing this product was first performed an experimental design to establish the best pre-treatment prior to drying. This was several freezing times (20 and 24 hours) and temperature (-18 and -20 ° C). From this, it was determined that it is best to freeze for 20 hours at -18 ° C. After that, another experimental design was performed to establish the time (2, 3 and 4 hours) and the optimal temperature (65, 75 and 85 ° C) for drying the product and to have a good rehydration quality. The results, performed using a weighting table and evaluating rehydration range, volume expansion and humidity, show that the best temperature and drying time was 3 hours at 65 ° C. Finally a sensory evaluation was performed to assess product acceptance, which had a level of pleasure of 3.97 locating it close to the category "I like it" which means that it had a good level of acceptance.Este trabajo tuvo como objetivo estudiar los efectos de diferentes tiempos y temperaturas de congelación y deshidratación en el rehidratado de un arroz para consumo instantáneo para el mercado ecuatoriano. Esto debido a que en la actualidad el consumo y la demanda de productos pre-elaborados que sean fáciles y rápidos de preparar han tenido un gran crecimiento. Para determinar el mejor proceso de elaboración del producto, se realizó primero un diseño experimental para establecer el mejor tiempo (20 o 24 horas) y temperatura (-18 o -20°C) de congelación previo al secado. De esto se determinó que lo mejor es una congelación por 20 horas a -18°C. Después se realizó otro diseño experimental para establecer el tiempo (2, 3 o 4 horas) y la temperatura (65, 75 o 85°C) óptimos de secado para que el producto tenga una buena rehidratación. Los resultados, interpretados mediante una tabla de ponderación que midieron rango de rehidratación, volumen de expansión y humedad, mostraron que el mejor tiempo y temperatura de secado fue 3 horas a 65°C. Finalmente se realizó una evaluación sensorial para evaluar aceptación del producto, el cual tuvo un nivel de agrado de 3,97 situándolo muy cerca de la categoría “me gusta” lo que significa que tuvo un buen nivel de agrado