Lightning-caused forest fires are one of the major natural disturbances in Ontario managed boreal forests. Survival of these forests with fires for centuries shows that such disturbances are integral to the boreal ecosystem and its ecological functioning. Characterizing the fire regimes defined by fire ignition frequency, fire sizes and their spatial distribution patterns etc. thus can help to improve our understanding of the boreal forest dynamics and provide guidance for management practices attempting to maintain biodiversity and achieve sustainability. In this thesis the lightning-caused fire ignitions data for four ecoregions in Ontario managed boreal forests (3E, 3W, 3S and 4S) for 1960–2009 were analyzed using pattern analysis and density estimation to determine the spatial nature of fire ignitions. These fire ignition spatial patterns were further used (as weighted ignition scenario) to simulate forest fire regimes in the study area. Fire regimes were also simulated using spatially unweighted ignitions (unweighted ignition scenario). Non-spatial (total number of fires, total burn area, number of fires by size classes, annual burn fraction) and spatial (spatial burn probability) indicators of the simulated fire regimes under both ignition scenarios were compared to test the null hypothesis that modeled forest fire regime is not affected by the spatial patterns of input fire ignitions. All data analysis were performed for individual ecoregions. Spatial pattern of ignitions were analyzed using the nearest neighbour index and Ripley’s K-function. Ignition densities were estimated using the adaptive kernel density estimation method and the fire regimes were simulated using BFOLDS (Boreal Forests Landscape Dynamics Simulator). Results showed that lightning-caused fire ignitions are clustered in all ecoregions. Fire ignition density also varied spatially within ecoregions. Overall fire ignition density was highest in the northwestern ecoregion (4S) and lowest in the eastern ecoregion (3E), which corresponds to the combined gradient of effective humidity and temperature in Ontario. For each ecoregion, comparison of non-spatial simulated fire regime indicators showed statistically non-significant differences between unweighted and weighted ignitions. The spatial burn probability however captured clear spatial differences between unweighted and weighted ignitions. Spatial differences in spatial burn probability between both ignition scenarios were more prominent in ecoregions of high fire occurrence. Results of the weighted ignition scenario closely followed the spatial patterns of the estimated fire ignition density in the study area. Based on these results this thesis rejects the null hypothesis and emphasizes that ignition patterns must be considered in simulating fire regime in Ontario boreal forests.

I syfte att förbättra kunskapsläget kring människors beteenden vid bränder och utrymningar studerades fyra brandsituationer hämtade från ett flertal verkliga händelser ur ett beslutsfattande- och riskbedömningsperspektiv. Det teoretiska underlaget hämtades ur Kahnemans och Tverskys forskning kring heuristiker (Kahneman och Tversky, 1974; Kahneman, Slovic & Tversky, 1982; Gilovich, Griffin & Kahneman, 2002). För ändamålet användes tre heuristiska regler: tillgänglighet, representativitet och affekt. Dessa tre heuristiker möjliggör ögonblickssnabba riskbedömningar genom att allt utom en särskild variabel bortses från i beslutsprocessen. När människor blir stressade tenderar de att förlita sig mer på heuristiker i sina bedömningar. Analysen visar att det är rimligt att anta att de beteenden som observerats i samband med bränder i de fyra fallen beror på beslut huvudsakligen fattade med hjälp av någon av de tre heuristikerna. Denna kunskap kan öppna upp nya möjligheter för att förebygga dödsfall på grund av felaktiga beteenden i samband med bränder och utrymningar.

Οι δασικές πυρκαγιές αποτελούν αναπόσπαστο κομμάτι των Μεσογειακών οικοσυστημάτων επηρεάζοντας το φυσικό κύκλο διαδοχής της βλάστησης, αλλά και τη δομή και λειτουργία τους. Τα τελευταία χρόνια παρατηρείται αύξηση των δασικών πυρκαγιών αυξάνοντας ιδιαίτερα το επιστημονικό ενδιαφέρον. Η χρησιμοποίηση της δορυφορικής τηλεπισκόπησης στη χαρτογράφηση των καμένων εκτάσεων έχει τριάντα χρόνια ιστορία ως εργαλείο χαρτογράφησης αλλά και παρακολούθησης της εξέλιξης των καμένων εκτάσεων. Η χαρτογράφηση των δασικών πυρκαγιών με τη χρήση δορυφορικών δεδομένων είναι και σήμερα ένα εν ενεργεία αντικείμενο έρευνας της τηλεπισκόπησης. Πολλά χαρακτηριστικά παραδείγματα υπάρχουν στη διεθνή βιβλιογραφία με ερευνητικό αντικείμενο τη χαρτογράφηση των καμένων εκτάσεων με τη χρήση πολλαπλών τύπων δορυφορικών δεδομένων, όμως ο αριθμός αυτών που διαπραγματεύονται για την ίδια πυρκαγιά πολλούς τύπους δεδομένων είναι περιορισμένος. Στην παρούσα διδακτορική διατριβή επιχειρείται για πρώτη φορά η χαρτογράφηση των καμένων εκτάσεων με εκτεταμένη χρήση διαφόρων τύπων δορυφορικών εικόνων πολλαπλής φασματικής και χωρικής διακριτικής ικανότητας που έχουν αποκτηθεί για την ίδια πυρκαγιά (Πάρνηθα, 2007). Πιο συγκεκριμένα, αντικείμενο έρευνας αποτέλεσε η χαρτογράφηση των άκαυτων νησίδων εσωτερικά της περιμέτρου της πυρκαγιάς, καθώς και η διερεύνηση των παραγόντων που διαμορφώνουν την ακρίβεια της χαρτογράφησης, η διερεύνηση της ευαισθησίας των τιμών ανάκλασης σε διαφορετικές αναλογίες καμένου/βλάστησης, καθώς και η εφαρμογή και αξιολόγηση διαφόρων δεικτών βλάστησης. Τα δορυφορικά δεδομένα που αξιολογήθηκαν προέρχονται από τους δορυφορικούς ανιχνευτές IKONOS, LANDSAT, ASTER και MODIS. Παράλληλα με τα αρχικά δεδομένα δημιουργήθηκε ένα σύνολο εικόνων πολλαπλής φασματικής και χωρικής κλίμακας. Αρχικά, εφαρμόστηκαν κλασικοί αλγόριθμοι επεξεργασίας εικόνας για τη γεωμετρική, ραδιομετρική και ατμοσφαιρική διόρθωση των δορυφορικών εικόνων. Στη συνεχεία, επεξεργάστηκε η υψηλής ανάλυσης εικόνα IKONOS, η οποία αποτέλεσε τη βάση για τον υπολογισμό του ποσοστού κάλυψης των καμένων εκτάσεων, της βλάστησης και του γυμνού εδάφους σε επίπεδο εικονοστοιχείου. Λαμβάνοντας υπόψη διαφορετικούς συνδυασμούς φασματικών και χωρικών αναλύσεων πραγματοποιήθηκαν συνολικά 420 ταξινομήσεις. Επιπλέον, οι φασματικοί δίαυλοι καθώς και 57 δείκτες βλάστησης που υπολογίστηκαν, συσχετίστηκαν με περιοχές διαφορετικών αναλογιών καμένης και άκαυτης βλάστησης, με σκοπό τη διερεύνηση της ευαισθησίας τους στην εκτίμηση του ποσοστού των καμένων και μη καμένων περιοχών. Συμπερασματικά, η χωρική διακριτική ικανότητα αποδεικνύεται ως ο σημαντικότερος παράγοντας για την αποτύπωση των άκαυτων νησίδων εσωτερικά της περιμέτρου της πυρκαγιάς, ενώ διαπιστώθηκε ότι συσχετίζεται άμεσα με τον αριθμό των χαρτογραφημένων νησίδων. Επιπλέον, το κοντινό και μέσο υπέρυθρο τμήμα του φάσματος αποδείχτηκαν σημαντικά για την εκτίμηση του ποσοστού του καμένου, ενώ το κόκκινο και κοντινό υπέρυθρο για την εκτίμηση του ποσοστού της βλάστησης. Το τελευταίο φαίνεται ότι διαδραματίζει σημαντικό ρόλο στον υπολογισμό του ποσοστού των καμένων εκτάσεων, ενώ το μέσο υπέρυθρο στον υπολογισμό του ποσοστού της βλάστησης. Οι δείκτες βλάστησης ελαχιστοποιούν τις επιδράσεις εξωτερικών παραγόντων, όπως είναι η επίδραση του εδάφους. Έτσι, οι ενδιάμεσες κατηγορίες κρίθηκαν πιο σύμφωνες φασματικά με τις διαφορετικές αναλογίες καμένου/βλάστησης, σε σχέση με τους αρχικούς φασματικούς δίαυλους, βάσει των οποίων υπολογίζονται οι δείκτες. Οι κλασικοί δείκτες, οι οποίοι ενσωματώνουν το κόκκινο και κοντινό υπέρυθρο μήκος κύματος έδειξαν καλύτερη προσαρμογή στην εκτίμηση του ποσοστού της βλάστησης. Αντίθετα, η τροποποιημένη εκδοχή τους, αντικαθιστώντας το κόκκινο με το μέσο υπέρυθρο τμήμα του φάσματος έδειξαν καλύτερη προσαρμογή στην εκτίμηση του ποσοστού των καμένων περιοχών, ταυτόχρονα με την υψηλή προσαρμογή για την εκτίμηση της βλάστησης. Τέλος, πραγματοποιήθηκε η ανασύσταση της πρόσφατης ιστορίας των πυρκαγιών (1984-2011) για την Αττική, εφαρμόζοντας πρόσφατα ανεπτυγμένες (ημι)αυτόματες τεχνικές χαρτογράφησης σε διαχρονικά LANDSAT δορυφορικά δεδομένα μεσαίας χωρικής διακριτικής ικανότητας. Τα αποτελέσματα αυτής της διαδικασίας οδήγησαν στη χαρτογράφηση των περιμέτρων των πυρκαγιών με σχετικά μεγάλη ακρίβεια, ενώ από τα μοντέλα παλινδρόμησης διαπιστώθηκε ότι οι διαφορές μεταξύ της καμένης έκτασης που υπολογίζεται από τα δορυφορικά δεδομένα και αυτά τα οποία καταγράφονται από τη Δασική Υπηρεσία αποδίδονται στον αριθμό των δορυφορικών εικόνων που χρησιμοποιούνται καθώς και στην ημερομηνία απόκτησης της πρώτης δορυφορικής εικόνας. / Forest fires, an integral part of Mediterranean ecosystems, affect the natural cycle of vegetation succession and the ecosystem’s structure and function. Recently, the increment in frequency of fires has increased the concern of the scientific community. The use of remote sensing in burned land mapping has a 30 year long history as tool in mapping and monitoring of forest fire. Despite this long period, burned land mapping using satellite data is still an active research topic in satellite remote sensing. Many characteristic examples of satellite remote sensing studies of burned land mapping and monitoring can be found in the literature, however studies dealing with a multisource data set for the same fire event are limited. The present thesis attempted to map burned surfaces using a multisource satellite data set of multiple spectral and spatial resolution acquired for the same fire event (Parnitha, 2007). In particular, the aims of the thesis were to delineate the unburned patches within fire scar perimeter and explore the factors influence the classification accuracy, to explore the sensitivity of spectral reflectance values to different burn and vegetation ratios, as well as to examine and evaluate some vegetation indices. The satellite data used were acquired from IKONOS, LANDSAT, ASTER and MODIS. Along with the basic data set, a spatially degraded satellite data over a range of coarser resolutions were created. Firstly, classical image processing algorithms were applied to correct geometrically, radiometrically and atmospherically the satellite images used. The pan-sharpened IKONOS served as the basis to estimate the percent of cover of burned areas, vegetation and bare land, at pixel level. Totally 420 classifications have been implemented considering different combinations of spectral and spatial resolutions. Additionally, the spectral bands and 57 versions of some classical vegetation indices were correlated with different burned and vegetation ratios in order to explore their sensitivity. Conclusively, spatial resolution is the most important factor for the delineation of the unburned patches within the fire scar perimeter, while proved to be strongly correlated with the number of the mapped islands. Moreover, the near and middle infrared channels were the most important ones to estimate the percentage of burned area, while the red and near infrared were the most important channels to estimate the percentage of vegetation. The latter, seemed to play a more significant role in estimating the percent of burned area while the middle infrared seemed to play a more significant role in estimating the percent of vegetation. Vegetation indices are less sensitive to external parameters of the vegetation by minimizing external effects, such as soil impact. Thus, the semi-burned classes were spectrally more consistent to their different fractions of scorched and non-scorched vegetation, than the original spectral channels based on which these indices are estimated. The classical indices, which incorporate the red-near infrared space showed better performance to estimate the percent of the vegetation. In contrast, the modified version of the classical indices, by replacing the red with the middle infrared channel showed the highest performance to estimate the percent of burned areas, apart from the high performance in the estimation of the vegetation. Finally, in the present thesis maps with the reconstruction of the recent fire history of Attica region were created, in a spatially explicit mode using (semi)automated image processing techniques in a series of multi-temporal medium-resolution LANDSAT images. The results showed that the fire-scar perimeters were captured with considerably high accuracy, while regression modeling showed that the differences between the area burned estimated from satellite data and that recorded by the forest service can be explained by the number of satellite images used followed by the acquisition date of the first image.

Il est bien établi que l'exposition à court terme aux particules fines dans l’air ambiant en milieu urbain a des effets sur la santé. Toutefois, peu d'études épidémiologiques ont évalué la relation entre les particules fines (PM2.5) de sources spécifiques comme celles dérivées de feux de forêt et les effets sur la santé. Pour l’instant, les risques de mortalité et de morbidité associés aux PM2.5 résultant de la combustion de végétation semblent similaires à ceux des PM2.5 urbaines. Dans le présent mémoire, nous avons comparé deux méthodes pour quantifier les risques de mortalité et de morbidité associés à l'augmentation des niveaux de PM2.5 à Montréal, dérivées de deux épisodes des feux de forêts majeurs dans le Nord du Québec. La première approche consistait à comparer les décès et les visites aux urgences observées enregistrées au cours des deux épisodes à Montréal à leurs moyennes respectives attendues durant des jours de référence. Nous avons également calculé la surmortalité et la surmorbidité prédites attribuables aux PM2.5 lors des épisodes, en projetant les risques relatifs (RR) rapportés par l’Environmental Protection Agency (EPA) des États-Unis pour les PM2.5 urbaines, ainsi qu’en appliquant des fonctions de risque estimées à partir des données estivales spécifiques à Montréal. Suivant la première approche, nous avons estimé une surmortalité de +10% pendant les deux épisodes. Cependant, aucune tendance claire n'a été observée pour les visites à l'urgence. Et suivant la 2e approche, la surmortalité prédite attribuable aux niveaux des PM2.5 dérivées des feux de forêt étaient moins élevés que ceux observés, soit de 1 à 4 cas seulement. Une faible surmortalité attribuable aux niveaux élevés des PM2.5 issues de feux de la forêt boréale du Québec a été estimée par les fonctions de risque ainsi que par la méthode de comparaison des décès observés aux moyennes attendues, sur l’Île de Montréal, située à des centaines de km des sites de feux. / The association between adverse health effects and short term exposure to urban particulate matter in ambient air is well established. Few epidemiological studies have assessed the relation between fine particles (PM2.5) of specific sources like forest fires, and health effects. According to the published literature to date, risks of mortality and morbidity associated with PM2.5 from combustion sources appear similar to those of urban PM2.5. In the present thesis, we compared two methods to quantify mortality and morbidity risks associated with the increase in PM2.5 levels in Montreal, due to two major forest fire episodes in Northern Quebec. In the first approach we compared mortality and emergency room visits counts recorded during the episodes to their respective averages expected on “usual” days. We also calculated deaths and emergency room visits attributable to PM2.5 levels on episode days, using the range of relative risks (RRs) reported by the United-States Environmental Protection Agency (EPA) for urban PM2.5 levels, as well as specific risk functions developed with Montreal summer data. With the first method, increases of deaths of more than 10% were observed for both episodes. However no clear tendency was observed in emergency room visits. Estimated attributable deaths associated with the increase in PM2.5 levels were smaller than those observed and ranged between 1 to 4 cases. PM2.5 from Quebec boreal forest fires were associated with small increases in mortality estimated either with the risk function method or by contrasting observed deaths on “episode” days to“usual” days, on the Island of Montreal, hundreds of kilometers away from the fire sites.

Disturbances, such as herbivory and fire are commonplace in savanna ecosystems. The effects of herbivory and fire on growth and defences of adult trees is a much studied filed in plant ecology. However, there are comparatively few studies that have investigated the effects of herbivory and fire on seedling growth, defences and establishment. African Acacia trees are common and widespread, and are suggested to be keystone species in savanna ecosystems. They have been shown to significantly positively increase soil characteristics, such as soil moisture and infiltration, while also increasing spatial heterogeneity of savannas. These trees are distinguishable by their array of physical and chemical defences. Physical defences are either in the form of spines (physiologically costly to produce, thus considered inducible) or prickles (physiologically cheap to produce, thus considered constitutive), while condensed tannins are the most common form of chemical defences. Adult Acacia trees have been shown on several occasions to be highly resilient to disturbance events, primarily due to their large size. However, the effects of herbivory and fire on Acacia seedlings have been little studied despite their apparent importance for our understanding of African savanna ecosystem functioning. In two separate experiments, this thesis aimed to investigate the individual and combined effects of simulated herbivory and fire on the regrowth, defences, and total non-structural carbohydrates (TNC) of the seedlings of several Acacia species, while also testing the Resource Availability Hypothesis (RAH) (14 Acacia species) and the Expanded Growth-Differentiation Balance Hypothesis (GDBH) (three Acacia species). The RAH (Coley, Bryant & Chapin 1985) and the GDBH (Loomis 1932) both assume that arid-adapted (resource-poor) species are slow growing, with low tissue turnover rates. Contrastingly, humid-adapted (resource-rich) species have fast growth rates and thus a high tissue turnover rate. Therefore, arid-adapted species are predicted to invest more carbohydrate reserves in defence after a disturbance event, in order to defend new photosynthetic material. Conversely, humid-adapted (resource-rich) species are predicted to invest carbohydrate reserves into increased growth after a disturbance event, in order to compensate for tissue loss. The first greenhouse experiment found that, in accordance with the RAH, humid-adapted species displayed elevated growth rates compared to arid-adapted species. Overall, defences significantly increased after herbivory, but significantly decreased after fire. Herbivory was also shown to significantly reduce TNC stores in roots more than fire. We found that arid-adapted species did indeed invest more carbohydrate stores (TNC) into defence, and displaying an increase in spine and prickle abundance, spine and prickle length, and condensed tannin concentration. Humid-adapted species displayed an increase in growth rather than in defence, with the majority of species only increasing one defensive trait. Humid-adapted species also displayed significant trade-offs (negative correlations) between new stem growth and defence traits, while arid-adapted species overall did not display any significant trade-offs between stem growth and increased defences. The majority of arid-adapted species also displayed an allometric effect for spine abundance and length, with an increase in one trait led to an increase in the other. Prickles were found to be inducible, despite the assumption that due to low physiological cost, they are no inducible. Herbivory and fire were shown to not be substitutable in their effects on Acacia seedlings in a controlled experimental setting. The second greenhouse experiment tested the Expanded Growth-Differentiation Balance Hypothesis (GDBH) in the seedlings of A. erioloba, A. karroo, and A. nilotica using five levels of nutrient availability. Overall, spine abundance and spine length displayed a unimodal trend in all three species, with spine abundance and spine length being greatest at a nutrient availability of 800 mg/ ℓ. Spine abundance, spine length and condensed tannins increased significantly after herbivory, but were shown to significantly decrease after fire. We found that with an increase in nutrient availability, the growth of stems and roots, along with the production of TNC in roots and stems of all species significantly increased. Our data provide mixed support for the assumptions and predictions of the expanded GDBH. The regrowth of stems and physical defences were consistent with the GDBH. Chemical defences (i.e. condensed tannins) were however, inconsistent with the predictions of the GDBH. We have shown that Acacia seedlings are highly resilient to disturbance events, while the growth responses of Acacia seedlings are underpinned by TNC stores in roots. Simulated herbivory and fire are often substituted for one another in controlled experiments. However, we have shown that the effects of herbivory and fire have significantly different effects on regrowth patterns of Acacia seedlings. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2011.

Contemporary and historical studies of the flora of the Hluhluwe Game Reserve (HGR), have emphasised the woody component whilst little work has been performed on the herbaceous vegetation. This is particularly true with regard to the responses of grasses to historical fire and bush clearing. This study attempted to elucidate some of these responses. Of all the variables considered in this study, woody cover, altitude, the number of fire events, geological and soil parent material are the most important affecting the abundance of grasses in this reserve. Most of these variables are not independent in their effects on grass abundance, with varying degrees of correlation between each other. Certain species appear to be restricted to particular geological substrates. Along with successional changes in the composition and cover of the woody community, due to seemingly inevitable bush encroachment, there is a parallel change in grassland communities in this reserve. In the absence of clearing, numerous fires, higher altitudes, igneous geology and soils derived from igneous parent material delays this succession, whilst sedimentary geology at lower altitudes and fire frequencies accelerates the trend to high woody cover and associated grass species. The grass communities in HGR were shown to be significantly affected by bush clearing and fire. Specifically the number of clearings and fire events, physical bush clearing during 1957 - 1963 and chemical bush clearing during 1968 - 1978. From the responses of species in relation to the various key environmental variables, viz. geological substrate, woody cover and burning and clearing, a model of species response to these variables was developed. With increased fire and bush clearing frequency, the grass communities shift from closed woodland, shade tolerant species through to more open fire climax grassland. These are also more productive communities producing palatable grasses. Validation of aspects of the model were successful - the model having a relatively high predictive capability. Further testing of the model over different substrates and under different clearing regimes is necessary. With regular fires and re-clearing in some bush cleared areas, the vegetation of this reserve should be able to be maintained as productive and diverse grasslands. In the absence of this management, the grass communities will shift towards species associated with woodlands. Bush clearing activities would appear to be most effective over sites on igneous substrate, at higher altitudes, where successional rates are slowest. This is in comparison to sites at lower altitudes over sedimentary geology. / Thesis (M.Sc.)-University of Natal, Durban, 1992.

Fire, natural or of anthropologic origin is a recurrent phenomenon in South African mesic grasslands. The species composition of these grasslands is sensitive to fire frequency and there exists a permanent fire-species relationship syndrome. The shift follows a general trend where, in the absence of fire for longer periods, the native grass species, possibly the most economically important grass species, give space to relatively less desirable and invasive species accompanied by significant decline in basal cover. Though much is known as to how the floristic composition of the grassland changes in response to fire, the underlying mechanisms responsible for changes in plant vigour and species composition are not fully understood. There exists limited information on germination requirements of the local flora and how recruitment of the species is influenced by fire, fire-related factors and the interaction of these factors among themselves is virtually unknown. Since the discovery by DE LANGE and BOUCHER (1990), plant-derived smoke is being widely studied as an important germination cue and the theme has been the subject of intense experimental research and theoretical work. Germination studies conducted on South African Fynbos, Californian Chaparral, and Australian species have illustrated the widespread ability of plant-derived smoke in promoting germination of species from both fire and non-fire prone habitats. Studies have also showed that plant-derived smoke plays a significant role in vegetative growth of many plants including horticultural and agricultural crops, though mechanisms of smoke action in enhancing germination and promoting plant growth are still under active research. This study sought to gain insight into the role of fire and fire-related cues and other related factors on germination and seedling growth of key grass species from fire-prone grassland in South Africa. In this study, various investigations were conducted on different aspects related to smoke-induced seed germination. Furthermore, in depth examinations were conducted on the effects of fire-related factors such as smoke, heat, soil and nutrients on seed germination and seedling growth of representative key mesic grassland species from South Africa. Laboratory-based germination and vigour experiments were conducted using smoke solutions. The aim was to examine if the strong fire-species relationship syndrome we encounter in post-fire mesic grassland in South Africa is related to the effect of plant-derived smoke on germination and seedling growth. In addition, the interaction of plant-derived smoke solutions with temperature was examined by incubating seeds at a range of temperatures. Treating seeds with smoke-water and butenolide, the germination rate (GR) and final germination percentage (FGP) were greater in 3 of the 6 species. Themeda triandra Forssk. and Tristachya leucothrix Trin. ex Nees showed the greatest response, with final germination increased from 43% to 67% and 35% to 63% respectively. These smoke solutions have also significantly enhanced germination in Eragrostis tef (Zucc.) Trotter from 62% to 80%. The degree of responsiveness varied from species to species and across different temperatures. Findings from this study suggested that plant-derived smoke and its interaction with temperature significantly influence the germination and seedling growth of the South African mesic grassland species, which can further impact on the grassland composition. To characterise the role of plant-derived smoke on certain economically important seed traits, the effect of smoke-water and a smoke-isolated butenolide on seed germination and seedling growth of Eragrostis tef (grass species which has moderately good tolerance to east African drought) was investigated at a range of temperatures, light conditions and osmotic potentials. Smoke-water (1:500 v/v) and butenolide (10ˉ⁸ M) treatment of the seeds increased percentage germination, seedling vigour and imbibition from high to low osmotic potential. These results suggested that smoke solutions have characteristics with overriding effects toppling stresses exerted from high temperature and low osmotic potential, thereby widening the temperature and moisture zone over which germination can occur. Furthermore, these findings suggested that the mode of smoke action in promoting seed germination is likely to be linked to the role of smoke in facilitating water uptake by seeds (imbibition). A simple and rapid bioassay was implemented to detect the germination activity of extracts from soils in pre/post-burn status. Soil samples taken from burnt, unburnt and adjacent plots at depths of 0-2, 2-4, 4-6 and 6-8 cm before and after burning mesic grassland in South Africa were analysed for germination activity over an eight-week period. Soil samples were extracted using dichloromethane and bioassayed using Grand Rapids lettuce (Lactuca sativa L.) achenes. The Grand Rapids lettuce seeds exhibited several-fold greater germination percentages when treated with extracts from burnt soil compared to the other plots. The magnitude of such an activity declined through time since burn. The Grand Rapids lettuce seeds also showed significantly greater germination percentage when treated with unburnt soil extracts compared to the control (distilled water) which indicates the existence of other factors controlling germination in unburnt soil. Germination percentage was negatively influenced in the adjacent plots which reflected the inhibitory role of smoke on adjacent plots neighbouring the burn. Findings from this study suggested that the germination activity of a burning plant-material (smoke) indeed diffuses into the soil and its persistence declines with time. Furthermore, the findings implied that fire and smoke may significantly influence the germination of the soil seed bank of mesic grassland in South Africa. The effect of smoke solutions of various concentrations and their interaction with soil macronutrients NPK in influencing seedling growth of three selected grass species namely, Eragrostis curvula, Panicum maximum and Themeda triandra was investigated. These grass species were selected on the basis of the contrasting response they previously showed to smoke treatments. Results showed that the interaction between species, treatment and nutrients for seedling vigour index was highly significant (P < 0.001). In the absence of NPK elements, the smoke solutions generally enhanced seedling growth in Themeda triandra, while suppressing seedling vigour indices of Eragrostis curvula and Panicum maximum. It is ecologically significant that not only smoke but also its interaction with soil macronutrients appears to be important in structuring the post-fire regeneration and colonisation processes. To examine the effect of fire-associated cues of smoke and high temperature on germination and seedling emergence from the mesic grassland soil seed bank in South Africa, and disentangle responsible factors, the effect of heat and smoke-water on seedling emergence and the resultant effect on biomass production was examined in a greenhouse tray experiment over 90 days. Soil seed bank samples obtained from 0-5 cm top soil were treated with smoke-water solution (SW 1:500 v/v), heat (H = 100 °C for 15 min) and heat + smoke-water (H = 100 °C for 15 min + SW = 1:500 v/v) combined. Significantly, the highest number of seedlings emerged from soil seed bank samples treated with heat + smoke-water combined followed by smoke-water alone. Heat + smoke-water treatment of soil seed bank samples also significantly enhanced the rate of seedling emergence and total dry biomass production. Heat treatment by itself was not statistically different from the control in many respects. Generally, these results suggest that both heat and smoke are important germination cues and play a curial role on germination and seedling emergence from the mesic grassland soil seed bank. A greater number of fire-loving Themeda triandra seedlings emerged from soils treated with smoke, though this was not statistically significant. Seedling emergence indicators showed that seedling emergence was favoured more by smoke and smoke + heat treatments compared to the control. Seedling growth indicators also showed that soil samples treated with smoke or smoke + heat combined produced significantly higher biomass than untreated samples. In general, findings from this comprehensive study suggest that plant-derived smoke and its interaction with temperature (heat) and soil nutrients significantly influences seed germination and seedling growth of South African mesic grassland species differently, this can further influence the grassland composition. The association of certain fire-climax species with the re-occurrence of fire can partly be explained due to the association of such species with fire-induced changes in the habitat. Post-fire conditions of low nutrient (NPK) availability, presence of high heat and smoke cues in the habitat may favour the competitive ability of native short and smoke-responsive species such as Themeda triandra and Tristachya leucothrix over those characteristic species of fertile habitats such as Eragrostis curvula and other non-smoke-responsive species. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2010.

There are few methods available for the spatial-temporal analysis of polygon data. This research develops a new method for spatial-temporal analysis of moving polygons (STAMP). Using an event-based framework, polygons from neighboring time periods are related by spatial overlap and proximity. The proximity spatial relation is defined by an application specific distance threshold. STAMP is demonstrated in the spatial-temporal analysis of a wildfire burning over small spatial and temporal scales, and in the spatial-temporal analysis of mountain pine beetle (Dendroctonus ponderosae Coleoptera: Hopkins) movement patterns over large spatial and temporal scales. The mountain pine beetle analysis found that short range movement patterns of mountain pine beetles occurred at different beetle population levels. Spot proliferation occurred most when beetle presence was increasing slowly, perhaps moving into new areas for the first time. When beetle presence increased rapidly, local expansion, or spot growth, was a more common movement pattern. In the Pine Pass study area. long range dispersal markedly extended the northeast border of the mountain pine beetle range.

Lightning-caused forest fires are one of the major natural disturbances in Ontario managed boreal forests. Survival of these forests with fires for centuries shows that such disturbances are integral to the boreal ecosystem and its ecological functioning. Characterizing the fire regimes defined by fire ignition frequency, fire sizes and their spatial distribution patterns etc. thus can help to improve our understanding of the boreal forest dynamics and provide guidance for management practices attempting to maintain biodiversity and achieve sustainability. In this thesis the lightning-caused fire ignitions data for four ecoregions in Ontario managed boreal forests (3E, 3W, 3S and 4S) for 1960–2009 were analyzed using pattern analysis and density estimation to determine the spatial nature of fire ignitions. These fire ignition spatial patterns were further used (as weighted ignition scenario) to simulate forest fire regimes in the study area. Fire regimes were also simulated using spatially unweighted ignitions (unweighted ignition scenario). Non-spatial (total number of fires, total burn area, number of fires by size classes, annual burn fraction) and spatial (spatial burn probability) indicators of the simulated fire regimes under both ignition scenarios were compared to test the null hypothesis that modeled forest fire regime is not affected by the spatial patterns of input fire ignitions. All data analysis were performed for individual ecoregions. Spatial pattern of ignitions were analyzed using the nearest neighbour index and Ripley’s K-function. Ignition densities were estimated using the adaptive kernel density estimation method and the fire regimes were simulated using BFOLDS (Boreal Forests Landscape Dynamics Simulator). Results showed that lightning-caused fire ignitions are clustered in all ecoregions. Fire ignition density also varied spatially within ecoregions. Overall fire ignition density was highest in the northwestern ecoregion (4S) and lowest in the eastern ecoregion (3E), which corresponds to the combined gradient of effective humidity and temperature in Ontario. For each ecoregion, comparison of non-spatial simulated fire regime indicators showed statistically non-significant differences between unweighted and weighted ignitions. The spatial burn probability however captured clear spatial differences between unweighted and weighted ignitions. Spatial differences in spatial burn probability between both ignition scenarios were more prominent in ecoregions of high fire occurrence. Results of the weighted ignition scenario closely followed the spatial patterns of the estimated fire ignition density in the study area. Based on these results this thesis rejects the null hypothesis and emphasizes that ignition patterns must be considered in simulating fire regime in Ontario boreal forests.

La xarxa catalana a Madrid en el segle XVIII. Un estudi sobre els homes de negocis catalans i el comerç és una aproximació a la situació mercantil de totes aquelles persones que, procedents del Principat, van partir rumb la capital espanyola després de la Guerra de Successió. Si durant el segle anterior les activitats econòmiques catalanes es caracteritzaven per l'exportació a Europa de vins i aiguardents, el nou marc polític inaugurat arran de la guerra oferia diferents opcions. L'annexió de la Corona catalano-aragonesa amb la integració aranzelària tancava la porta del comerç exterior, però n'obria d'altres: el comerç interior i el comerç americà. Entendre per què els catalans triaven una d'aquestes possibilitats, vendre a la Península o deixar-se seduir per l'aventura colonial, serà l'objectiu de la tesi. / The Catalan network in Madrid the 18th century. An study about businessmen and trade is an approach to the mercantile situation of all those persons from the Principality that split direction the Spanish capital after the War of Succession. If during the former century the export to Europe of wines and eaux de vie characterized the Catalan economic activities, the new political frame opened as a result of the war offered different options. The annexation of the Catalan-Aragonese Crown with the costumes integration closed the door of the foreign trade, but it opened other ones: the inner trade and American trade. Understanding why the Catalans chose one of these possibilities, to sell at the Peninsula or to tend to the colonial adventure, will be the goal of the thesis.