A GEOBIA methodology for fragmented agricultural landscapes

Very high resolution remotely sensed images are an important tool for monitoring fragmented agricultural landscapes, which allows farmers and policy makers to make better decisions regarding management practices. An object-based methodology is proposed for automatic generation of thematic maps of the available classes in the scene, which combines edge-based and superpixel processing for small agricultural parcels. The methodology employs superpixels instead of pixels as minimal processing units, and provides a link between them and meaningful objects (obtained by the edge-based method) in order to facilitate the analysis of parcels. Performance analysis on a scene dominated by agricultural small parcels indicates that the combination of both superpixel and edge-based methods achieves a classification accuracy slightly better than when those methods are performed separately and comparable to the accuracy of traditional object-based analysis, with automatic approach

Knowledge-Based Classification of Grassland Ecosystem Based on Multi-Temporal WorldView-2 Data and FAO-LCCS Taxonomy

Grassland ecosystems can provide a variety of services for humans, such as carbon storage, food production, crop pollination and pest regulation. However, grasslands are today one of the most endangered ecosystems due to land use change, agricultural intensification, land abandonment as well as climate change. The present study explores the performance of a knowledge-driven GEOgraphic-Object—based Image Analysis (GEOBIA) learning scheme to classify Very High Resolution(VHR)imagesfornaturalgrasslandecosystemmapping. Theclassificationwasappliedto a Natura 2000 protected area in Southern Italy. The Food and Agricultural Organization Land Cover Classification System (FAO-LCCS) hierarchical scheme was instantiated in the learning phase of the algorithm. Four multi-temporal WorldView-2 (WV-2) images were classified by combining plant phenology and agricultural practices rules with prior-image spectral knowledge. Drawing on this knowledge, spectral bands and entropy features from one single date (Post Peak of Biomass) were firstly used for multiple-scale image segmentation into Small Objects (SO) and Large Objects (LO). Thereafter, SO were labelled by considering spectral and context-sensitive features from the whole multi-seasonal data set available together with ancillary data. Lastly, the labelled SO were overlaid to LO segments and, in turn, the latter were labelled by adopting FAO-LCCS criteria about the SOs presence dominance in each LO. Ground reference samples were used only for validating the SO and LO output maps. The knowledge driven GEOBIA classifier for SO classification obtained an OA value of 97.35% with an error of 0.04. For LO classification the value was 75.09% with an error of 0.70. At SO scale, grasslands ecosystem was classified with 92.6%, 99.9% and 96.1% of User’s, Producer’s Accuracy and F1-score, respectively. The findings reported indicate that the knowledge-driven approach not only can be applied for (semi)natural grasslands ecosystem mapping in vast and not accessible areas but can also reduce the costs of ground truth data acquisition. The approach used may provide different level of details (small and large objects in the scene) but also indicates how to design and validate local conservation policies

Introducing GEOBIA to landscape imageability assessment: a multi-temporal case study of the nature reserve “Kózki”, Poland

Geographic object-based image analysis (GEOBIA) is a primary remote sensing tool utilized in land-cover mapping and change detection. Land-cover patches are the primary data source for landscape metrics and ecological indicator calculations; however, their application to visual landscape character (VLC) indicators was little investigated to date. To bridge the knowledge gap between GEOBIA and VLC, this paper puts forward the theoretical concept of using viewpoint as a landscape imageability indicator into the practice of a multi-temporal land-cover case study and explains how to interpret the indicator. The study extends the application of GEOBIA to visual landscape indicator calculations. In doing so, eight different remote sensing imageries are the object of GEOBIA, starting from a historical aerial photograph (1957) and CORONA declassified scene (1965) to contemporary (2018) UAV-delivered imagery. The multi-temporal GEOBIA-delivered land-cover patches are utilized to find the minimal isovist set of viewpoints and to calculate three imageability indicators: the number, density, and spacing of viewpoints. The calculated indicator values, viewpoint rank, and spatial arrangements allow us to describe the scale, direction, rate, and reasons for VLC changes over the analyzed 60 years of landscape evolution. We found that the case study nature reserve (“Kózki”, Poland) landscape imageability transformed from visually impressive openness to imageability due to the impression of several landscape rooms enclosed by forest walls. Our results provide proof that the number, rank, and spatial arrangement of viewpoints constitute landscape imageability measured with the proposed indicators. Discussing the method’s technical limitations, we believe that our findings contribute to a better understanding of land-cover change impact on visual landscape structure dynamics and further VLC indicator development

Analysis of Land Cover Distribution and Spatial Pattern of Landscape Fragmentation and Connectivity in the Taperoá and Upper Paraíba River Basins, Brazil

As bacias do alto curso do rio Paraíba e do Taperoá localizam-se na zona semiárida do Estado da Paraíba. Grande parte da delimitação do semiárido possui bosques de Caatinga, que por suas condições bioclimáticas, diversidade e endemismos, torna-se um bioma singular, estendendo-se por uma superfície de 844.453Km2 IBGE (2010). Diante do exposto, o objetivo deste trabalho foi analisar a distribuição do uso, cobertura do solo, padrão espacial da fragmentação e conectividade da paisagem nas bacias do alto Paraíba e do Taperoá. O mapeamento foi feito a partir de classificação GEOBIA de imagens MSI do satélite Sentinel 2, com o uso do software GUIDOS. Os resultados apontam a maior presença de caatinga e maior conectividade no sul e noroeste na bacia do alto Paraíba e no sudoeste da bacia do TaperoáLa cuenca de alto curso de río Paraíba y del Taperoá ubican-se en la zona semiárida del Estado de Paraíba. La mayor parte del semiárido encuentra se los bosques de Caatinga, que por su condición bioclimática, diversidad y endemismo, es un bioma singular, que extiende-se por una superficie de 844.453Km2 IBGE (2010). El objetivo dela investigación es analizar la distribución del uso, cobertura del suelo, padrón espacial de la fragmentación y conectividad del paisaje en la cuenca del alto curso del rio Paraíba y Taperoá. La especialización fue hecha por una clasificación GEOBIA del imagines MSI del satélite Sentinel 2, y trabajos en el software GUIDOS. Los resultados apuntan la mayor presencia de las áreas de caatinga en cuantidad y conectividad en el sur y noreste del alto Paraíba y en sureste del Taperoá.The Upper Paraíba and Taperoá river basin are located in the semiarid zone of Paraíba State. Much of the delimitation of the semiarid region has Caatinga forests, which, due to its bioclimatic conditions, diversity and endemism, become a singular biome, extending over a surface area of 844,453Km2 IBGE (2010). The objective of this study was to evaluate soil use and cover, spatial pattern of fragmentation and connectivity of the Upper Paraíba and Taperoá basin. The mapping was done from GEOBIA classification of MSI images of Sentinel 2 satellite, and worked on GUIDOS software. The vegetation cover and the water and bioclimatic condition of the surveyed area were used. The results point to a greater presence of caatinga areas in quantity and connectivity in the northwest of Upper Paraíba and in the southwest of Taperoá

An OBIA for fine-scale land cover spatial analysis over broad territories: demonstration through riparian corridor and artificial sprawl studies in France

International audienceSpatial analysis using fine-scale information over broad territories is essential to define efficient restoration strategies from local to national scale. We designed an OBIA dedicated to produce operationally reliable fine-scale information over broad territories. The originality of our OBIA lies particularly in the top-down approach for the construction of the classification tree and the use of „knowledge-based rules‟ classification technique. The implementation of this OBIA over the two study areas – (i) the Normandy region for riparian area land cover mapping (5600 km² riparian area) and (ii) fours departments over the Languedoc-Roussillon region (22644 km²) – demonstrates the operability of our approach (time-efficient, reproducible, transferable, portable). Broad scale spatial analysis conducted from resulting maps demonstrate the interest of using fine-scale information and highlight that OBIA, following our approach, will be at very short run a broadly applicable method to carry out such analysis

UAS photogrammetry and object-based image analysis (GEOBIA): erosion monitoring at the Kazár badland, Hungary

L

The effect of scaling methods on the calculation of environmental indices

Landscape structure quantification is a subject of great interest in the environmental sciences because of the practical advantages it offers, including calculation of the environmental indices useful for land management, ecology and many other fields. A trend of developing new systems of environmental indices can be observed in European Institutions such as EEA and EUROSTAT, but there has been criticism about approaches based on Corine Land Cover (CLC). One of the aims of this article is to review the method of this database preparation for the purpose of calculating environmental indices. This study tests the ability of three methods to scale categorical maps and retaining as much of the original landscape structure information as possible. The vector scaling method is comparable to the preparation of the CLC data. Two other methods use Geo-Object Image Analysis as the main tool for classification. The scaling is performed in this method through building a hierarchy of objects and scaling the raster imagery. The results are compared and evaluated for scale effects and the calculation of environmental indices on the basis of the scaled data. There is no universal method for all the characteristics of the landscape pattern. The GEOBIA-based methods demonstrate greater applicability to fine grained structural and landscape configuration analyses. The vector scaling method is applicable mainly to landscape configuration, its results are also better for visualization of the scaled map.

La dynamique du paysage forestier boréal mixte en réponse aux feux et à l'aménagement forestier sous l'influence des changements climatiques

Le paysage forestier boréal dominé par la forêt mixte est le résultat des interactions complexes des conditions abiotiques, de la succession et des régimes de perturbations, qu’influencent les processus écologiques qui opèrent au niveau du peuplement et à l’échelle du paysage. Les changements climatiques prévus pour les prochains siècles devraient modifier les régimes de perturbations naturelles tels que les incendies de forêt, affectant le flux de bois vers les marchés de produits ligneux. C’est pour cette raison que la gestion des forêts boréales mixtes a suscité une préoccupation généralisée concernant le maintenant de sa biodiversité, sa résilience et sa capacité d’adaptation à conserver les avantages sociaux et économiques qu’elles procurent à la société. Cette préoccupation a conduit à proposer une modification de l'exploitation dite traditionnelle vers une approche d’aménagement forestier écosystémique, qui tente d'imiter les patrons de perturbations naturelles afin de conserver la forêt à l’intérieur des limites historiques de variation. En dépit de tous ces efforts, au cours des dernières décennies dans l'est du Canada, la forêt mixte est passée d'un paysage dominé par la forêt mature vers un paysage fragmenté avec une quantité croissante de peuplements à prédominance de feuillus. Toutefois, notre compréhension des variations spatiotemporelles des paysages forestiers et des caractéristiques des peuplements issus après feu et après récolte demeure insuffisante. L'objectif de cette thèse était de caractériser les changements à moyen terme des mosaïques de forêts mixtes de l'est du Canada et d'améliorer notre connaissance des relations entre ces changements et les variations attendues des feux de forêt sous l’effet des changements climatiques ainsi que du régime de perturbations anthropiques. La première étape pour atteindre cet objectif a été de comprendre la dynamique historique du paysage dans un gradient nord-sud de forêts mixtes de l’est du Canada. Pour cette raison, le chapitre 2 présente une étude historique de l’hétérogénéité du paysage forestier, mesuré en termes de composition et configuration du paysage ainsi que leur interaction avec les feux de forêt historiques dans un paysage aménagé. En utilisant les images Landsat de 1985 à 2013, la cartographie et des mesures spatiales nous avions suivi l’évolution de la composition dans le temps des forêts selon 4 classes : résineux, résineux mixtes à dominance résineuse, mixte à dominance feuillue et feuillus. Cette étude montre que la composition résineuse a dominé la mosaïque en 1985 et représentait un tiers de la superficie de l'étude. De plus, la classe résineuse a enregistré la plus forte diminution avec un taux de 1,7% par an par rapport aux autres couvertures forestières. Les mesures indiquent que les forêts résineuses matures, qui dominaient auparavant le paysage dans l'est du Canada, ont été principalement transformées par les pratiques forestières en un paysage plus hétérogène et fragmenté. Le chapitre 3 détaille le modèle de paysage forestier LANDIS-II utilisé pour évaluer les relations entre les feux de forêt et l’aménagement forestier sous scénarios de réchauffement climatique futur (RCP 2.6,RCP 4.5 et RCP 8.5), via la biomasse forestière (AGB) et la productivité primaire nette (ANPP). Les projections du modèle ont démontré que les régimes de perturbation sont les variables les plus significatives qui déterminent les variations de l'AGB et de l'ANPP. L’aménagement forestier apparait comme le facteur le plus important des variations observées dans les forêts du sud du gradient comparativement au nord, probablement parce que cette région présente des forêts plus âgées et avec une composition d’intérêt commercial pour respecter la possibilité forestière. À l’opposé, les forêts du nord du gradient présentaient un effet mixte du changement climatique et de l’aménagement forestier sur l'AGB et l'ANPP, probablement parce qu'un grand nombre de zones propices à la récolte avaient déjà été brulées, limitant ainsi la quantité du territoire disponible pour la récolte. En général, bien que l'on s'attende à une augmentation des superficies brulées en raison du changement climatique, l'intensification de l’aménagement forestier semble être le principal facteur de l'augmentation des feuillus et des peuplements mixtes et de la diminution des peuplements résineux, ainsi que de la diminution de la AGB et ANPP, principalement dans les forêts du sud. Le chapitre 4 détaille l'utilisation de LANDIS-II pour modéliser les trajectoires de succession de la gestion post-feu et post-aménagement suite aux scénarios de changement climatique. L’évolution de l’AGB post-perturbations nous a permis de constater que, contrairement aux perturbations causées par les feux, l’aménagement forestier a modifié les voies de succession conduisant à des changements de composition allant de forêts à prédominance de feuillus à une forêt mixte favorisant la prévalence d'essences de feuillus, même après 300 ans. Cette tendance est exacerbée par les scénarios de changement climatique, qui donneront un avantage aux forêts dominées par des espèces intolérantes à l'ombre, en particulier dans les écorégions où elles sont peu présentes (forêts mixtes centrales et septentrionales de la zone d’étude). De plus, ces pratiques d’aménagement conduisent à des indices de formes de forêt plus sinueuses au niveau spatial du paysage, indiquant une augmentation de la fragmentation. Les résultats obtenus mettent en évidence l'échec des pratiques d’aménagement actuelles à imiter la succession naturelle après feu et compromettent le maintien des biens et des services de ces écosystèmes. Les changements climatiques prévus pour le prochain siècle devraient modifier les régimes de perturbations naturelles (tels que les feux de forêt). En outre, il existe des activités d’aménagement telles que la récupération du bois à des fins industrielles qui perturbent les forêts pour satisfaire la demande croissante de produits ligneux. Nos résultats suggèrent que l'approvisionnement en bois à long terme serait menacé dans l'est du Canada. Par conséquent, certaines stratégies devraient être mises en oeuvre pour adapter l’aménagement des forêts aux changements climatiques attendus et à maintenir l'avenir des forêts

Assessment of habitat quality and landscape connectivity for forest-dependent cracids in the Sierra Madre del Sur Mesoamerican biological corridor, Mexico

Assessing landscape connectivity allows us to identify critical areas that impede or facilitate the movement of organisms and their genes and to plan their conservation and management. In this article, we assessed landscape connectivity and ecological condition of the habitat patches of a highly biodiverse region in Chiapas, Mexico. We employed data of three cracid species with different characteristics in habitat use and mobility. The habitat map of each species was derived from a spatial intersection of the models of potential distribution and a high-resolution map of current land cover and land use. The ecological condition of vegetation types was evaluated using 75 field plots. Structure of landscape was estimated by fragmentation metrics, while functional connectivity was assessed using spatially explicit graph analysis. The extent of suitable habitat for Oreophasis derbianus, Penelopina nigra, and Penelope purpurascens correspond to 25%, 46%, and 55% of the study area (5,185.6 km2), respectively. Although the pine-oak forests were the most fragmented vegetation type, habitats of the three species were well connected, and only 4% to 9% of the fragments located on the periphery of the corridor had low connectivity. Landscape connectivity depends mainly on land uses with an intermediate and lower ecological condition (secondary forests and coffee agroforestry systems). Therefore, we suggest that in addition to promoting the improvement in connectivity in fragmented forests, conservation efforts should be aimed at preventing the conversion of mature forests into agricultural uses and maintaining agroforestry systems