Evaluation of the impacts of Hurricane Hugo on the land cover of Francis Marion National Forest, South Carolina using remote sensing

Hurricane Hugo struck the South Carolina coast on the night of September 21, 1989 at Sullivan’s Island, where it was considered a Category 4 on the Saffir-Simpson scale when the hurricane made landfall (Hook et al. 1991). It is probably amongst the most studied and documented hurricanes in the United States (USDA Southern Research Station Publication 1996). There has been a Landsat TM based Hugo damage assessment study conducted by Cablk et al. (1994) in the Hobcaw barony forest. This study attempted to assess for a different and smaller study area near the Wambaw and Coffee creek swamp. The main objective of this study was to compare the results of the traditional post-classification method and the triangular prism fractal method (TPSA hereafter, a spatial method) for change detection using Landsat TM data for the Francis Marion National Forest (FMNF hereafter) before and after Hurricane Hugo’s landfall (in 1987 and 1989). Additional methods considered for comparison were the principal component analysis (PCA hereafter), and tasseled cap transform (TCT hereafter). Classification accuracy was estimated at 81.44% and 85.71% for the hurricane images with 4 classes: water, woody wetland, forest and a combined cultivated row crops/transitional barren class. Post-classification was successful in identifying the Wambaw swamp, Coffee creek swamp, and the Little Wambaw wilderness as having a gain in homogeneity. It was the only method along with the local fractal method, which gave the percentage of changed land cover areas. Visual comparison of the PCA and TCT images show the dominant land cover changes in the study area with the TCT in general better able to identify the features in all their transformed three bands. The post-classification method, PCA, and the TCT brightness and greenness bands did not report increase in heterogeneity, but were successful in reporting gain in homogeneity. The local fractal TPSA method of a 17x17 moving window with five arithmetic steps was found to have the best visual representation of the textural patterns in the study area. The local fractal TPSA method was successful in identifying land cover areas as having the largest heterogeneity increase (a positive change in fractal dimension difference values) and largest homogeneity increase (a negative change in fractal dimension difference values). The woody wetland class was found to have the biggest increase in homogeneity and the forest class as having the biggest increase in heterogeneity, in addition to identifying the three swamp areas as having an overall increased homogeneity

Application de l'identification d'objets sur images à l'étude de canopées de peuplements forestiers tropicaux : cas des plantations d'Eucalyptus et des mangroves

This PhD work aims at providing information on the forest structure through the analysis of canopy properties as described by the spatial distribution and the crown size of dominant trees. Our approach is based on the Marked Point Processes (MPP) theory, which allows modeling tree crowns observed in remote sensing images by discs belonging a two dimensional space. The potential of MPP to detect the trees crowns automatically is evaluated by using very high spatial resolution optical satellite images of both Eucalyptus plantations and mangrove forest. Lidar and simulated reflectance images are also analyzed for the mangrove application. Different adaptations (parameter settings, energy models) of the MPP method are tested and compared through the development of quantitative indices that allow comparison between detection results and tree references derived from the field, photo-interpretation or the forest mockups. In the case of mangroves, the estimated crown sizes from detections are consistent with the outputs from the available allometric models. Other results indicate that tree detection by MPP allows mapping, the local density of trees of young Eucalyptus plantations even if crown size is close to the image spatial resolution (0.5m). However, the quality of detection by MPP decreases with canopy closeness. To improve the results, further work may involve MPP detection using objects with finer shapes and forest data measurements collected at the tree plant scale.La thèse s'inscrit dans l'étude de la structuration des forêts à partir des propriétés de la canopée telles que décrites par la distribution spatiale ou la taille des houppiers des arbres dominants. L'approche suivie est fondée sur la théorie des Processus Ponctuels Marqués (PPM) qui permet de modéliser ces houppiers comme des disques sur images considérées comme un espace 2D. Le travail a consisté à évaluer le potentiel des PPM pour détecter automatiquement les houppiers d'arbres dans des images optiques de très résolution spatiale acquises sur des forêts de mangroves et des plantations d'Eucalyptus. Pour les mangroves, nous avons également travaillé sur des images simulées de réflectance et des données Lidar. Différentes adaptations (paramétrage, modèles d'énergie) de la méthode de PPM ont été testées et comparées grâce à des indices quantitatifs de comparaison entre résultats de la détection et références de positionnement issues du terrain, de photo-interprétation ou de maquettes forestières. Dans le cas des mangroves, les tailles de houppier estimées par détection restent cohérentes avec les sorties des modèles allométriques disponibles. Les résultats thématiques indiquent que la détection par PPM permet de cartographier dans une jeune plantation d'Eucalyptus la densité locale d'arbres dont la taille des houppiers est proche de la résolution spatiale de l'image (0.5m). Cependant, la qualité de la détection diminue quand le couvert se complexifie. Ce travail dresse plusieurs pistes de recherche tant mathématique, comme la prise en compte des objets de forme complexe, que thématiques, comme l'apport des informations forestières à des échelles pertinentes pour la mise au point de méthodes de télédétection

Detecting and mapping forest nutrient deficiencies: eucalyptus variety (Eucalyptus grandis x and Eucalyptus urophylla) trees in KwaZulu-Natal, South Africa.

Doctoral Degree. University of KwaZulu-Natal, Pietermaritzburg.Abstract available in PDF

Use of remote sensing for land use policy formulation

Research projects described include: (1) identifying coniferous forest types in Michigan using LANDSAT imagery; (2) investigating synoptic temperature patterns in Michigan as determined via GOES and HCMM thermal imagery; (3) land surface change detection using satellite data and a geographic data base; (4) determining soil map unit composition by electronic scanning densitometry; and (5) delimiting areas of virus infection in vineyards and blueberry fields in southwestern and western Michigan. Contractual activities involve important farmlands inventory, changes in aquatic vegetation in Saginaw Bay, digitized soil association map of Michigan, and aerial photography for hybrid-poplar research. On-going projects are also being conducted in Jamaica, Honduras, the Dominican Republic and Kenya

LANDSAT information for state planning

The transfer of remote sensing technology for the digital processing of LANDSAT data to state and local agencies in Georgia and other southeastern states is discussed. The project consists of a series of workshops, seminars, and demonstration efforts, and transfer of NASA-developed hardware concepts and computer software to state agencies. Throughout the multi-year effort, digital processing techniques have been emphasized classification algorithms. Software for LANDSAT data rectification and processing have been developed and/or transferred. A hardware system is available at EES (engineering experiment station) to allow user interactive processing of LANDSAT data. Seminars and workshops emphasize the digital approach to LANDSAT data utilization and the system improvements scheduled for LANDSATs C and D. Results of the project indicate a substantially increased awareness of the utility of digital LANDSAT processing techniques among the agencies contracted throughout the southeast. In Georgia, several agencies have jointly funded a program to map the entire state using digitally processed LANDSAT data

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

Etude de l’hybridation inter-spécifique entre espèces du genre Coffea en Nouvelle-Calédonie : distribution des niches favorables et structuration de la diversité

Coffee trees are originated from inter-tropical forests of Africa and Madagascar and their diversification origin areas are highly threatened. Among the 103 species of the Coffea genus, only three are cultivated: C. arabica, C. canephora and C. liberica. C. canephora has the widest natural distribution in tropical African forests, and its genetic diversity is structured in five distinct groups. The study of the genetic diversity structuring has revealed a particular importance of the Dahomey gap floristic breaking as biogeographic barrier, as well as the past climatic variations on the diversity structuring (model to study the “refuge theory”). A core set of both wild and cultivated (represented in majority by inter-group hybrids) accessions was selected to characterize the introduced diversity in New-Caledonia (since 1856). On introduced New-Caledonian sample, high levels of genetic diversity have been revealed for C. canephora and C. liberica while as expected, low level of diversity has been revealed for C. arabica. These three species (C. liberica to a lesser extent) have been introduced in different regions of New Caledonia for their culture. Because of economical reasons, a lot of traditional coffee plantations have been abandoned during the Second World War, leaving the cultivars to evolve in natural conditions. Inter-specific hybridizations are occurring between coffee species (at a level of 3% according to the study of a tri-specific population) thanks to a removal of reproductive barriers facilitated by particular environmental conditions. An environmental expertise based on the comparisons of environmental conditions between Sarramea region and African origin regions of the three species has underlined the favorable environmental combinations to sympatry and inter-specific hybridizations. Equilibrium between draining and humidity, precipitations sequences and the forest cover are important parameters maintaining a favorable microclimate. The canopy forest study by remote sensing tools has reinforced the predicting distribution model of favorable niches to inter-specific hybridization thanks to the information brought on canopy heterogeneity and large tree crowns and to the spatial resolution improving the detection of micro-habitats. Favorable niches are micro-environments distributed throughout the study area. The question is to underline the preservation of such de novo adapted coffee genetic resources.Les caféiers sont des arbres ou arbustes natifs des forêts intertropicales d'Afrique, de Madagascar, des Mascareignes et des Comores et leurs aires d'origine ou de diversification sont en forte régression. Parmi les 103 espèces du genre Coffea seules trois sont cultivées : C. arabica, C. canephora et C. liberica. L‟espèce C. canephora est celle du genre qui a la plus grande distribution dans les forêts tropicales africaines, et sa diversité génétique est structurée en cinq groupes bien distincts. L‟étude fine de la structuration de sa diversité génétique a révélé une importance particulière de la rupture floristique du Dahomey gap en tant que barrière biogéographique, ainsi que des variations climatiques du passé sur la structuration de la diversité (modèle d'étude des refuges forestiers du Quaternaire). Une collection de référence (core-collection) de la diversité sauvage et cultivée (représentée par une majorité d'hybrides inter-groupes) a été mise en place pour caractériser la diversité introduite en Nouvelle-Calédonie (depuis 1856). Cette diversité s'est révélée être élevée pour C. canephora et C. liberica et comme attendu, faible pour C. arabica. C. canephora et C. arabica (C. liberica de manière plus anecdotique) ont été introduites un peu partout en Nouvelle-Calédonie pour leur culture. Pour des raisons économiques, beaucoup de plantations traditionnelles ont été abandonnées au moment de la deuxième guerre mondiale, laissant les arbres de caféiers évoluer de manière naturelle. Des hybridations inter-spécifiques se produisent entre ces trois espèces (à hauteur de 3% dans une population tri-spécifique) grâce à une levée de barrières à la reproduction, permise par une conjoncture environnementale particulière. Une expertise environnementale fine, basée sur la comparaison des conditions environnementales entre la région de Sarraméa et les régions d'origine des trois espèces en Afrique, a permis de mettre en exergue les combinaisons environnementales favorables à la cohabitation des espèces et à leur hybridation inter-spécifique. L'équilibre entre drainage et humidité, un régime pluviométrique particulier et la présence d'un couvert forestier, sont des paramètres environnementaux importants qui maintiennent un microclimat favorable. L'étude du couvert forestier par télédétection a permis de renforcer le modèle de prédiction des niches favorables aux hybridations inter-spécifiques grâce à l‟information apportée quant à l'hétérogénéité et la présence de gros arbres dans la canopée ainsi que à l'amélioration de la résolution spatiale qui permet la détection fine de micro-habitats. Les niches favorables sont des micro-environnements répartis dans la région d'étude. Il s‟agit de mettre l‟accent sur la conservation d‟une telle néo-diversité adaptée et de valoriser ce patrimoine naturel

Impact of climate change on agricultural and natural ecosystems

This book illustrates the main results deriving from fourteen studies, dealing with the impact of climate change on different agricultural and natural ecosystems, carried out within the Impact of Climate change On agricultural and Natural Ecosystems (ICONE) project funded by the ALFA Programme of the European Commission. During this project, a common methodology on several Global Change-related matters was developed and shared among members of scientific communities coming from Latin America and Europe. In order to facilitate this interdisciplinary approach, specific mobility programmes, addressed to post-graduate, Master and PhD students, have been organized. The research, led by the research groups, was focused on the study of the impact of climate change on various environmental features (i.e. runoff in hydrological basins, soil erosion and moisture, forest canopy, sugarcane crop, land use, drought, precipitation, etc). Integrated and shared methodologies of atmospheric physics, remote sensing, eco-physiology and modelling have been applied