Caractérisation spatio-temporelle de la dynamique des trouées et de la réponse de la forêt boréale à l'aide de données lidar multi-temporelles

La forêt boréale est un écosystème hétérogène et dynamique façonné par les perturbations naturelles comme les feux, les épidémies d'insectes, le vent et la régénération. La dynamique des trouées joue un rôle important dans la dynamique forestière parce qu'elle influence le recrutement de nouveaux individus au sein de la canopée et la croissance de la végétation avoisinante par une augmentation des ressources. Bien que l'importance des trouées en forêt boréale fut reconnue, les connaissances nécessaires à la compréhension des relations entre le régime de trouées et la dynamique forestière, en particulier sur la croissance, sont souvent manquantes. Il est difficile d'observer et de mesurer extensivement la dynamique des trouées ou les changements de la canopée simultanément dans le temps et l'espace avec des données terrain ou des images bidimensionnelles (photos aériennes,...) et ce particulièrement dans des systèmes complexes comme les forêts ouvertes ou morcelées. De plus, la plupart des recherches furent menées en s'appuyant sur seulement quelques trouées représentatives bien que les interactions entre les trouées et la structure forestière furent rarement étudiées de manière conjointe. Le lidar est un système qui balaye la surface terrestre avec des faisceaux laser permettant d'obtenir une image dense de points en trois dimensions montrant les aspects structuraux de la végétation et de la topographie sous-jacente d'une grande superficie. Nous avons formulé l'hypothèse que lorsque les retours lidar de tirs quasi-verticaux sont denses et précis, ils permettent une interprétation de la géométrie des trouées et la comparaison de celles-ci dans le temps, ce qui nous informe à propos de leur influence sur la dynamique forestière. De plus, les mesures linéaires prises à différents moments dans le temps permettraient de donner une estimation fiable de la croissance. Ainsi, l'objectif de cette recherche doctorale était de développer des méthodes et d'accroître nos connaissances sur le régime de trouées et sa dynamique, et de déterminer comment la forêt boréale mixte répond à ces perturbations en termes de croissance et de mortalité à l'échelle locale. Un autre objectif était aussi de comprendre le rôle à court terme des ouvertures de la canopée dans un peuplement et la dynamique successionelle. Ces processus écologiques furent étudiés en reconstituant la hauteur de la surface de la canopée de la forêt boréale par l'utilisation de données lidar prises. en 1998, 2003 (et 2007), mais sans spécifications d'études similaires. L'aire d'étude de 6 km² dans la Forêt d'Enseignement et de Recherche du Lac Duparquet, Québec, Canada, était suffisamment grande pour capter la variabilité de la structure de la canopée et de la réponse de la forêt à travers une gamme de peuplements à différents stades de développement. Les recherches menées lors de cette étude ont révélé que les données lidar multi-temporelles peuvent être utilisées a priori dans toute étude de télédétection des changements, dont l'optimisation de la résolution des matrices et le choix de l'interpolation des algorithmes sont essentiels (pour les surfaces végétales et terrestres) afin d'obtenir des limites précises des trouées. Nous avons trouvé qu'une technique basée sur la croissance de régions appliquée à une surface lidar peut être utilisée pour délimiter les trouées avec une géométrie précise et pour éliminer les espaces entre les arbres représentant de fausses trouées. La comparaison de trouées avec leur délimitation Iidar le long de transects linéaires de 980 mètres montre une forte correspondance de 96,5%. Le lidar a été utilisé avec succès pour délimiter des trouées simples (un seul arbre) ou multiples (plus de 5 m²). En utilisant la combinaison de séries temporelles de trouées dérivées du lidar, nous avons développé des méthodes afin de délimiter les divers types d'évènements de dynamique des trouées: l'occurrence aléatoire de trouées, l'expansion de trouées et la fermeture de trouées, tant par la croissance latérale que la régénération. La technique proposée pour identifier les hauteurs variées arbre/gaulis sur une image lidar d'un Modèle de Hauteur de Couvert (MHC) a montré près de 75 % de correspondance avec les localisations photogrammétriques. Les taux de croissance libre suggérés basés sur les donnés lidar brutes après l'élimination des sources possibles d'erreur furent utilisés subséquemment pour des techniques statistiques afin de quantifier les réponses de croissance en hauteur qui ont été trouvées afin de faire varier la localisation spatiale en respect de la bordure de la trouée. À partir de la combinaison de donnés de plusieurs groupes d'espèces (de conifères et décidues) interprétée à partir d'images à haute résolution avec des données structurales lidar nous avons estimé les patrons de croissance en hauteur des différents groupes arbres/gaulis pour plusieurs contextes de voisinage. Les résultats on montré que la forêt boréale mixte autour du lac Duparquet est un système hautement dynamique, où la perturbation de la canopée joue un rôle important même pour une courte période de temps. La nouvelle estimation du taux de formation des trouées était de 0,6 %, ce qui correspond à une rotation de 182 ans pour cette forêt. Les résultats ont montré aussi que les arbres en périphérie des trouées étaient plus vulnérables à la mortalité que ceux à l'intérieur du couvert, résultant en un élargissement de la trouée. Nos résultats confirment que tant la croissance latérale que la croissance en hauteur de la régénération contribuent à la fermeture de la canopée à un taux annuel de 1,2 %. Des évidences ont aussi montré que les trouées de conifères et de feuillus ont des croissances latérales (moyenne de 22 cm/an) et verticales similaires sans tenir compte de leur localisation et leur hauteur initiale. La croissance en hauteur de tous les gaulis était fortement positive selon le type d'évènement et la superficie de la trouée. Les résultats suggèrent que la croissance des gaulis de conifères et de feuillus atteint son taux de croissance maximal à des distances respectives se situant entre 0,5 et 2 m et 1,5 et 4 m à partir de la bordure d'une trouée et pour des ouvertures de moins de 800 m² et 250 m² respectivement. Les effets des trouées sur la croissance en hauteur d'une forêt intacte se faisaient sentir à des distance allant jusqu'à à 30 m et 20 m des trouées, respectivement pour les feuillus et les conifères. Des analyses fines de l'ouverture de la canopée montrent que les peuplements à différents stades de développement sont hautement dynamiques et ne peuvent systématiquement suivre les mêmes patrons successionels. Globalement, la forêt est presqu'à l'équilibre compositionnel avec une faible augmentation de feuillus, principalement dû à la régénération de type infilling plutôt qu'une transition successionelle de conifères tolérants à l'ombre. Les trouées sont importantes pour le maintien des feuillus puisque le remplacement en sous-couvert est vital pour certains résineux. L'étude à démontré également que la dernière épidémie de tordeuse des bourgeons de l'épinette qui s'est terminée il y a 16 ans continue d'affecter de vieux peuplements résineux qui présentent toujours un haut taux de mortalité. Les résultats obtenus démontrent que lidar est un excellent outil pour acquérir des détails rapidement sur les dynamiques spatialement extensives et à court terme des trouées de structures complexes en forêt boréale. Les évidences de cette recherche peuvent servir tant à l'écologie, la sylviculture, l'aménagement forestier et aux spécialistes lidar. Ces idées ajoutent une nouvelle dimension à notre compréhension du rôle des petites perturbations et auront une implication directe pour les aménagistes forestiers en quête d'un aménagement forestier écologique et du maintien des forêts mixtes. ______________________________________________________________________________ MOTS-CLÉS DE L’AUTEUR : Perturbation naturelle, Dynamique forestière, Dynamique des trouées, Croissances latérales, Régénération, Succession, Lidar à retours discrets, Grande superficie, Localisation des arbres individuels, Croissance en hauteur

MANAGEMENT MATTER? EFFECTS OF CHARCOAL PRODUCTION MANAGEMENT ON WOODLAND REGENERATION IN SENEGAL

In Senegal, as in many parts of Africa, nearly 95% of its growing urban population depends on charcoal as their primary cooking energy. Extraction of wood for charcoal production is perceived to drive forest degradation. The Senegalese government and international donor agencies have created different forest management types with the ultimate goal of sustainably managing forests. This research combines local ecological knowledge, ecological surveys and remote sensing analysis to better understand questions related to how extraction for charcoal production and forest management affect Senegalese forests. Information derived from 36 semi-structured interviews suggests that the forests are degrading, but are depended on for income, grazing and energy. Interviewees understand the rules governing forest management types, but felt they had limited power or responsibility to enforce forest regulations. Ecological survey results confirmed that plots harvested for charcoal production are significantly different in forest structure and tree species composition than undisturbed sites. Across harvested and undisturbed and within forest management types the Combretum glutinosum species dominated (53% of all individuals and the primary species used for charcoal production) and demonstrated robust regenerative capacity. Few large, hardwood or fruiting trees were observed and had insufficient regenerative capacity to replace current populations. Species diversity was higher in co-managed areas, but declined after wood was harvested for charcoal production. Proximity to villages, roads and park edges in harvested and undisturbed plots and within forest management types had little impact on forest structure and tree diversity patterns with the harvesting of trees for charcoal spread consistently throughout the landscape. Remote sensing analysis with the MISR derived k(red) parameter demonstrated its ability to accurately classify broad land classes and showed potential when differentiating between pre- and post-harvest conditions over a three year time period, but could not accurately detect subtle changes in forest cover of known harvest time since last harvest in a single MISR scene. This research demonstrated the utility of multidisciplinary research in assessing the effects of charcoal production and forest management types on Senegalese forests; concluding that the effects of charcoal production on forest characteristics and regenerative capacity are consistent throughout all forest management types

Exploratory making: site inspired making as a tool for site analysis and design

Master of Landscape ArchitectureLandscape Architecture/Regional and Community PlanningJon D. HuntDesign tools (the method of making a designer uses to conceptualize or communicate the assembly of an object) are not simply secondary instruments to communicate designs through, but are the primary media through which designers contemplate and process design problems. Designers should utilize tools, whether digital or analog, with an awareness of each tool’s limitations and advantages and the possibilities they provide to each step of the design process. The intent of this report is to study how site inspired making methods can be used to observe and reveal information about a site, and thus contribute to the site analysis phase of design. Site inspired making methods are developed in this report through an exploratory research process. Exploratory research is a qualitative method used to provide flexibility in developing knowledge about a topic. An exploratory process was chosen to allow my focuses to shift as I make and reflect so my findings arise as I conduct the studies, not just from an initial hypothesis. Through an exploratory research process of making and reflecting this report answers the question: How do various methods of making develop and document my understanding of the site? Exploratory methods of drawing and sculpting are used to observe and reveal site information, and develop site-inspired artistic works. The site is a small, wooded lot and cove of Tuttle Creek Lake located northwest of Manhattan, Kansas. The research process is divided into an investigation phase in which I explored initial drawing and sculpting methods and an application phase in which I created a sculpture and series of drawings inspired by the site. I documented site conditions through observational drawing; revealed patterns and textures by drawing with and on site materials; developed parametric studies of balancing sculptures; discovered crystallization patterns by splattering ink on a frozen lake; designed a balancing sculpture inspired by the motion of ice sheets and driftwood on water; and created frost drawings by applying ink to soaked and frozen watercolor paper. Each method revealed different site qualities and informed my understanding of the site

Mapping Prosopis glandulosa (mesquite) invasion in the arid environment of South African using remote sensing techniques

A dissertation submitted to the School of Geography, Archaeology and Environmental Studies, Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of requirements for the degree of Master of Science in Environmental Sciences. Johannesburg, March 2016.Mapping Prosopis glandulosa (mesquite) invasion in the arid environment of South Africa using remote sensing techniques Mureriwa, Nyasha Abstract Decades after the first introduction of the Prosopis spp. (mesquite) to South Africa in the late 1800s for its benefits, the invasive nature of the species became apparent as its spread in regions of South Africa resulting in devastating effects to biodiversity, ecosystems and the socio-economic wellbeing of affected regions. Various control and management practices that include biological, physical, chemical and integrated methods have been tested with minimal success as compared to the rapid spread of the species. From previous studies, it has been noted that one of the reasons for the low success rates in mesquite control and management is a lack of sufficient information on the species invasion dynamic in relation to its very similar co-existing species. In order to bridge this gap in knowledge, vegetation species mapping techniques that use remote sensing methods need to be tested for the monitoring, detection and mapping of the species spread. Unlike traditional field survey methods, remote sensing techniques are better at monitoring vegetation as they can cover very large areas and are time-effective and cost-effective. Thus, the aim of this research was to examine the possibility of mapping and spectrally discriminating Prosopis glandulosa from its native co-existing species in semi-arid parts of South Africa using remote sensing methods. The specific objectives of the study were to investigate the spectral separability between Prosopis glandulosa and its co-existing species using field spectral data as well as to upscale the results to different satellites resolutions. Two machine learning algorithms (Random Forest (RF) and Support Vector Machines (SVM)) were also tested in the mapping processes. The first chapter of the study evaluated the spectral discrimination of Prosopis glandulosa from three other species (Acacia karoo, Acacia mellifera and Ziziphus mucronata) in the study area using in-situ spectroscopy in conjunction with the newly developed guided regularized random forest (GRRF) algorithm in identifying key wavelengths for multiclass classification. The GRRF algorithm was used as a method of reducing the problem of high dimensionality associated with hyperspectral data. Results showed that there was an increase in the accuracy of discrimination between the four species when the full set of 1825 wavelengths was used in classification (79.19%) as compared to the classification used by the 11 key wavelengths identified by GRRF (88.59%). Results obtained from the second chapter showed that it is possible to spatially discriminate mesquite from its co-existing acacia species and other general land-cover types at a 2 m resolution with overall accuracies of 86.59% for RF classification and 85.98% for SVM classification. The last part of the study tested the use of the more cost effective SPOT-6 imagery and the RF and SVM algorithms in mapping Prosopis glandulosa invasion and its co-existing indigenous species. The 6 m resolution analysis obtained accuracies of 78.46% for RF and 77.62% for SVM. Overall it was concluded that spatial and spectral discrimination of Prosopis glandulosa from its native co-existing species in semi-arid South Africa was possible with high accuracies through the use of (i) two high resolution, new generation sensors namely, WorldView-2 and SPOT-6; (ii) two robust classification algorithms specifically, RF and SVM and (iii) the newly developed GRRF algorithm for variable selection and reducing the high dimensionality problem associated with hyperspectral data. Some recommendations for future studies include the replication of this study on a larger scale in different invaded areas across the country as well as testing the robustness of the RF and SVM classifiers by making use of other machine learning algorithms and classification methods in species discrimination. Keywords: Prosopis glandulosa, field spectroscopy, cost effectiveness, Guided Regularised Random Forest, Support Vector Machines, Worldview-2, Spot-

Resource assessment of deciduous forests in Bangladesh

This research makes a new assessment of both the physical and social dimensions of deciduous forest resources located in the central part of Bangladesh. Satellite remote sensing data and techniques are used to detect spatial and temporal forest change, to measure forest biophysical variables and to appraise their potential for developing model predictions based on a field survey conducted in 2003. Post classification assessment and regression analysis were the main methods in remote sensing data analysis. The study focused on a part of deciduous forest (64 sq km) located in Madhupur thana for fine-scale forest assessment. Remote sensing results suggest that only 16 percent forest left in the study area compared to 3826 hectares in 1962. The forest biophysical variables show strong association with spectral information of satellite data. For instance, an R-squared of 0.79 for predicted variable (for tree height) was achieved while regressing with field data, indicating that remote sensing methods can be efficiently used even in the tropical forests where heterogeneity is common. The second part of the thesis focuses on the underlying social factors/drivers that impacted on the forest, ranging from social dynamics such as land tenancy disputes,historical legacies and local corruption to policy failure by employing the theoretical framework of political ecology. Political ecological analysis in this research helped to evaluate the role and inter-relations of power, the ideological dilemmas and methodological disputes (i.e. the way forest problems are perceived) over forest resources in the study area. Field survey and observation was also found useful in gathering information about social variables by interviewing local inhabitants, forest officials, NGO activists, and politicians. The research employs methodologies from both science (i.e. remote sensing) and social science (i.e. political ecology) and the findings suggest that these two strands can work together for the better management (including resource assessment, monitoring and progress evaluation) of resources in Bangladesh

Innovation, Research and Development and Capital Evaluation

The role of innovation is becoming increasingly crucial in modern societies. In particular, investments in Research and Development represent an important tool for promoting innovation and for enhancing the capital invested in the market. By now, innovation is linked with different concepts, from entrepreneurship to sustainability, from economics to management. The analysis of the innovation process involves different skills to overcome the high degree of competitiveness and allow higher levels of profits. In the text, the interactions among innovation, entrepreneurship, and ecosystems are investigated. It is an attempt to prepare the theoretical bases to face in an appropriate way the transformations of modern economic and organizational systems and to suggest adequate support policies

Cultivar Identification and Genetic Relatedness Among 25 Black Walnut (Juglans Nigra) Clones Based on Microsatellite Markers

A set of eight microsatellite markers was used to genotype 25 black walnut (Juglans nigra L.) clones within the Purdue University germplasm repository. The identities of 212 ramets were verified using the same eight microsatellite markers. Some trees were mislabeled and corrected as to clone using analysis of microsatellite markers. A genetic dendrogram was constructed to show the degree of genetic relatedness between clones. Two additional dendrograms, one based on crown architecture traits and the other on tree size and form traits, were also built and compared with the genetic dendrogram. The genetic dendrogram showed that these eight molecular markers had the ability to distinguish genetically related clones from less related ones. Crown architecture traits and tree size and form traits were able to group genetically related clones together, but less accurately than the genetic matrix

Model forest system: even-aged Douglas fir plantation with invasive Rhododendron

This thesis investigated the ecology and dynamics of Douglas fir (Pseudotsuga menziesii var. menziesii) dominated plantations at Coed-y-Brenin, Wales, whose transformation to continuous cover forestry has been delayed due to the presence of non-native invasive rhododendron (Rhododendron ponticum L). The literature review highlighted the complementary evolution of silviculture and modelling concepts to meet societal expectations and advance knowledge and understanding. It highlighted the development of hybrid, individual-based models, facilitated by advances in technology and complex systems theory to address contemporary pressures on forests. Three permanent sample plots of different ages, collectively covering 1.6ha of forest, were resurveyed in 2011, producing a 5-year growth series of mensuration data to parameterise an individual-based spatially-explicit forest growth model, SORTIE-ND. Vegetation, soil and light were surveyed to construct a statistical model of rhododendron seedling establishment and determine Ecological Site Classification. The limiting factors identified by the ecological site classification were a slightly dry Soil Moisture Regime and a poor Soil Nutrient Regime with moderate to high phosphorus and low nitrogen availability. SORTIE-ND was successfully parameterised using a maximum likelihood technique and simulated annealing. Parameterised relationships achieved an excellent level of fit to the data (R2 of 0.785 to 0.971), and the stand simulations produced DBH density plots comparable to observed size distributions. A Bayesian statistical model of rhododendron seedling establishment was produced. The cross-validated model predicted 81.3% of 24 survey stations with rhododendron seedlings, and 75% of 16 stations without seedlings, with an overall accuracy of 77.5%. Seedling establishment probability increased with soil O layer depth and decreased with increasing summed tree height in a 12x12 m neighbourhood. SORTIE-ND was then parameterised, using published literature, for the rhododendron lifecycle, to highlight knowledge gaps and as the novel first step towards full parameterisation from field data and the creation of decision support systems enabling foresters to interrogate the impact of different harvest regime scenarios on rhododendron invasion vulnerability