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This thesis describes the present nature of one facet of some of the flood plain forest stands in Denton County, Texas. The specific purpose was to demonstrate the presence or absence of difference between the Celtis laevigata (commonly known as the hackberry, southern hackberry or sugarberry) populations in stands on Denton Creek and Elm Fork of the Trinity River.

An updated silvics text for British Columbia. The need for an effective learning tool for silvics - one of the basic required courses in forestry - has been recognized by intructors as well as students across the province. The text prepared 18 years ago by Krajina et al. (1982) specifically for western Canada has become outdated. The silvics text by Burns and Honkala (1990) represents an up-to-date compendium but it is not an effective learning tool, particularly lacking in the linkage of silvics to ecological classification. Consequently, we revised and expanded “Distribution and Ecological Characteristics of Trees and Shrubs of British Columbia” (Krajina et al. 1982) using the available information on silvics, with some modification for BC and the results of recent silvics research done in BC. This material has been consolidated into a format that will help students understand the silvical attributes of tree species as well as the relationships between trees and their environments. To enhance learning, we have selected a series of slides illustrating the salient characteristics for each species and present this visual component on a CD-ROM included with the text. Also included is a large biogeoclimatic zone map of BC. The text, together with the CD-ROM, is intended to facilitate learning of silvics emphasizing its application to silviculture.

The sidewinder rattlesnake is found only in the low hot deserts of the southwestern United States and northwestern Mexico. It has adapted to this environment in various ways and thus is able to live under extremely demanding conditions. Previously published information on sidewinders is quite complete in certain respects and totally lacking in others. The present study represents an attempt to integrate the various aspects of sidewinder biology into a more cohesive unit. A large sidewinder population at Kelso Dunes, Mojave Desert, California, was intensively studied for three years. A number of parameters - physical, clmatic, behavioral and population - were investigated. Activity cycles are most closely tied to thermal regimes and considerably less so to rainfall and wind. An abundance of small mammal burrows on most of the study area provide thermal refugia on hot days and hibernacula during the winter. Because of the insulating properties of sand and the general lack of frost at Kelso, sidewinder hibernacula are probably scattered over the entire study area and appear to be rather superficial. Mating occurs generally in the spring and the young are born alive in early autumn. Whether the sidewinder reproductive cycle is annual or biennial was not determined. During warm weather sidewinders become active at dusk and may wander over the sand in any direction for over 1200 meters - mostly by sidewinding. The average distance travelled is much shorter, however. This nocturnal wandering probably serves as a dispersal mechanism, since mark and release studies showed no tendency towards homing or territorality. By midnight, however, even the most active sidewinders have formed resting craters and remain coiled therein until sunrise or later. Among rattlesnakes cratering is a feature unique to sidewinders. During the day the crater serves primarily for thermoregulation and less so for concealment, whereas at night this order of importance is reversed. Sidewinders prey upon any small reptile or mammal they can overpower and may actually do a considerable amount of feeding from ambush during the day. After feeding they become sedentary until digestion is largely completed, shifting position only to warm the food bolus during the day. Bio-telemetry studies indicated that the rate of heating or cooling may be more important in thermoregulatory behavior than the simple attainment of absolute thermal thresholds. On cool evenings sidewinders often bask on asphalt roads or railroad rails, using these surfaces as sources of reradiated heat. The sidewinder population is not uniformly distributed on the Kelso study area. More trackways were recorded in dune areas dotted with large clumps of vegetation with stable sand hummocks beneath them. In rockier areas with low vegetation and little sand, sidewinder trackways were few and mostly those of juveniles. This was attributed to inadequate burrows and the general lack of shade in such areas.

Ammonoids were collected from the Chainman Formation (Mississippian) of southeastern Nevada and southwestern Utah, the Phosphoria Formation (Permian) of southeastern Idaho and westernmost Wyoming, and the Thaynes Formation (Triassic) of northeastern Nevada and southeastern Idaho. The collections are interpreted to represent unwinnowed, untransported death assemblages of ammonoids which were subject to chemical conditions of the nekto-benthic environment. Associated lithologies were sampled and geochemically analyzed for content of phosphate and organic matter. Ammonoid fossil collections, combined with ammonoids ilustrated in the literature, were subjected to the graphical W and D analysis of Raup (1967). The basic parameteres involved in the description of shell-coiling geometry are whorl expansion rate, W, and the distance of the generating curve from the axis of coiling of the shell, D. Values of W determined range from 1.32 to 3.96, which correspond to slight and rapid increases in whorl height during coiling. Values of D determined range from 0.02 to 0.55, which correspond to extremes of involute and evolute coiling· geometries, respectively. Body chamber length corresponds with shell coiling geometry. Values determined in this study range from 10° to 540°. Corresponding W values are 3.96 and 1.50, whereas corresponding D values are 0.02 and 0.40, respectively. Average body chamber length in analyzed ammonoids is observed to decrease from 297° to 209° from Mississippian to Triassic time. Increase in apertural area accompanied this trend, and a possible consequence was that a greater range of prey sizes was afforded ammonoids with shorter body chambers. Life-orientation, described as the angle between the apertural plane and the gravitational vector, is calculated entirely on shell form and other geometrical considerations. Recent observations concerning Nautilus, combined with fossil evidence of epizoan encrustation suggest that ammonoids had an ability to control orientation, which is not observed from preservable morphology. From Mississippian to Triassic time, no trends in reconstructed life-orientation can be substantiated, based solely on Wand D values. Rotational stability during directed locomotion is important for conservation of the energy budget of this nektonic carnivorous organ­ ism. This property is calculated by the distance between the center of buoyancy and the center of gravity of the ammonoid. Values deter­ mined range from .04 (very unstable) to .16 (very stable). Corres­ ponding W values are 1.50 and 4.00 where corresponding D values are 0.20 and 0.02, respectively. A trend toward increasing average rota­tional stability (.07 to .10) is noted for amrnonoids from Mississippian to Triassic time. Efficiency in the utilization of calcium carbonate is the ratio of internal volume of the shell to volume of shell material. Values determined range from 5.80 to 7.25. Corresponding W values are 4.00 and 1.50, corresponding D values are 0.02 and 0.54, respectively. Abundant ammonoids found in black, phosphatic limestones rich in organic matter have an average efficiency value of 6.2. Abundant ammonoids from corresponding light-colored crystalline carbonates have an average efficiency value of 6.02, and indicate no correlation between effi­ciency and abundance. Size-frequency distributions are utilized in recognition of oppor­tunistic species of ammonoids. High numerical abundance, high mortality rate of juveniles, small size and conservation of calcium carbonate typifies the paleo-opportunistic species Cravenoceras, Psuedogastrio­ceras and Ophiceras. Biovolume-relative abundance distributions are useful in discerning the carrying capacity of the habitat both in number of individuals and species diversity. A large area under the biovolume-relative abun­dance profile indicates diversification under optimum environmental conditions; a small area under the profile indicates colonization of a stressful habitat. The Chainman, Phosphoria and Thaynes (Columbites Zone) Formations have ammonoid assemblages which show small areas under the biovolume-relative abundance profile, characteristic of anoxic environmental stress. The Permian stratigraphic units correlative with the Phosphoria Formation have ammonoid assemblages which show large areas under the profile and the associated lithologies, i.e., light­ gray,crystalline carbonates, suggest environments which could support a diversified ammonoid fauna, including large-sized species. Ontogenetic variation produces changes in the body chamber length, life orientation, rotational stability, and utilization of calcium carbonate of the analyzed genera of ammonoids. These ontogenetic variations usually resulted in the development of more involute shell-coiling geometries. Corresponding size-frequency distributions suggest increased mortality rates during ontogeny for some genera (Paracravenoceras, Medlicottia) which show decreasing efficiency in the utilization of calcium carbonate. (182 pages)

This thesis investigated the autecology of the dacine species, Bactrocera cacuminata (Hering) (Diptera: Tephritidae: Dacinae). I specifically focused on the adult phase of the life cycle and resources believed to be significant to this life stage. The prevailing paradigm in dacine ecology predicts that the larval host plant serves as the centre of dacine activity, a state mediated by mutualistic associations with fruit fly-type bacteria. Contrary to predictions, an explicit test of this hypothesis found that the host plant of B. cacuminata, Solanum mauritianum Scopoli, acted almost exclusively as a site for oviposition and larval development. Other key adult behaviours, most notably feeding and mating, were rare at the host plant. Even in disturbed habitats, the paucity of key adult behaviours such as mating was striking. Adult flies of this species were therefore hypothesized to be utilizing other components of their habitat, i.e. resources vital to their life history requirements. Some of the resources that B. cacuminata are known to respond to include sugar, protein, methyl eugenol and the host plant. The latter three resources are believed to be critical in the reproductive success of dacine flies in general. I assessed the physiological status of flies arriving at these resources to determine if flies of different status foraged for resources differently. In dacines, the internal reproductive structures of the male and female flies have been used as predictors of physiological status. I quantified expansion of the male ejaculatory apodeme in B. cacuminata with age of fly and found that there is a threshold apodeme size that is strongly correlated Abstract with sexual maturity. Maturity of female flies could be accurately predicted by ovarian development. Using these methods to assess the physiological and nutritional status of flies arriving at resources (larval host plant, protein and methyl eugenol) in the field, I discovered that only sexually mature and mated females were responding to the host plant, while the males at the host plant were sexually immature. This confirmed the hypothesis that the host plant primarily served as an oviposition site. Additionally, this study revealed that sexually mature males with high nutritional reserves were most commonly collected at methyl eugenol (a plant-derived chemical that elicits a strong response in males of many dacine species) at dusk, the time of peak sexual activity in this species. This indicated that methyl eugenol was perhaps a significant resource in the context of the reproductive behaviour of this species. Methyl eugenol (ME) is one of group of phenyl propanoids to which males of certain species of Dacinae respond. The current hypothesis of the role of these phenyl propanoids is that they function as pheromone precursor chemicals. Response to these chemicals is hypothesized to be a trait under sexual selection. In Bactrocera dorsalis (Hendel), this effect is so strong that a single feeding on ME results in a strong mating advantage up to a month after males feed on the chemical. Bactrocera cacuminata fed on multiple occasions on ME in a laboratory bioassay. After a single 24-hour exposure to ME, investigations of mating competitiveness did not reveal any obvious advantage for ME-fed males over unfed males. However, ME-fed males did enjoy a higher mating success 16 and 32 days after exposure to the chemical, suggesting that some physiological benefits unrelated to the pheromone synthesis was driving this delayed advantage. Investigation of the physiological consequences of feeding on ME revealed no enhancement of nutritional or energetic reserves, suggesting that the delayed mating advantage observed was more likely a chance event. An alternate hypothesis about the proximate function of ME, proposed by Robert Metcalf, is that it serves as a mate rendezvous site. As mating behaviour was notably absent at the host plant, I tested Metcalf’s hypothesis. A field-cage experiment, spatially separating adult resources (host plant, methyl eugenol, sugar and protein) clearly demonstrated that methyl eugenol was functioning as a mate rendezvous stimulus for B. cacuminata. This is the first direct support for Metcalf’s hypothesis. A synthesis of the literature revealed that significantly greater ecological and evolutionary information was required to understand the basis of dacine response to phenyl propanoids. Different dacine species may be utilizing these chemicals differently, even if their evolutionary origin may have been as a plant based kairomone. My studies show that generalizations on the ecology and behaviour of Dacinae, often extrapolated from research on a few pest species, do not hold up in the case of B. cacuminata. This suggests that a more autecological, species-specific approach is required in dacine research, before any predictive generalizations can be made.

Cyrtanthus nutans (RA Dyer) is a KwaZulu-Natal Province near-endemic species, classified as vulnerable in South Africa (IUCN Red Data categories). Literature references suggest that no recent ecological research has been conducted on Cyrtanthus nutans. Last assessed in 2007, the current study determined the demographics and the abiotic and biotic factors that influenced the distribution and range of Cyrtanthus nutans. Key determinants influencing the autecology, distribution and population dynamics of Cyrtanthus nutans were investigated. Anthropological factors influencing the decline of populations were addressed. Two investigations were undertaken for the current study on Cyrtanthus nutans in Dundee in North-western KwaZulu-Natal, South Africa namely a survey to determine the population dynamics and autecology of the species and the effect key determinants have on the recruitment and survival. Sites of occurrence and the ecological and anthropological factors that influence the existence of plants were documented. Experimental plots were conducted to determine the influence of climatological factors, fire and defoliation on the emergence and survival of Cyrtanthus nutans plants. A preference was found for soils with high nitrogen and organic carbon, low phosphorus and acidity levels situated on slopes of < 10% on mid to lower terrain slopes within an altitude range of between 1 100 and 1 300 m (a.m.s.l.) in the Sour Sandveld and Moist Tall Grassveld Bioresource Groups. The influence that climatological factors, fire and defoliation had on the emergence and seed recruitment of Cyrtanthus nutans were determined through a small plot experiment in the Dundee area. Mean relative humidity (%) and mean rainfall two weeks before emergence in conjunction with treatments were highly significant (P<0.001). Burning treatments B (fire inclusion and defoliation inclusion) and BC (fire inclusion and defoliation exclusion) were more highly significant on the emergence of Cyrtanthus nutans plants than any other treatments. ii | P a g e Increasing fragmentation of thriving populations of Cyrtanthus nutans populations is occurring through landuse change, mismanagement of veld and non-compliance of legislation. Continued monitoring and awareness is essential in the survival of this species. / Environmental Sciences / M. Sc. (Environmental Sciences)

Pericopsis elata is an African forestry species commercialized under the vernacular names afrormosia or assamela. It is one of the principal species commonly exploited for timber in the Democratic Republic of Congo (DRC) and in a lesser extent in Cameroon and Congo. In view of its sustainable resource exploitation, the species is in centre of numerous polemics notably in the European Union. It is one of the rare commercialized species that produce wood, since 1992, as listed in the CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora) annex II specifying that “the exploitation of afrormosia necessitate the deliverance and a prior presentation of exploitation permit”. The most important reserves of afrormosia are found in DRC. This doctoral thesis presents the ecology of this particular tree and its behaviour regarding forestry exploitation. It allows to inform the international organisms such as CITES as well as the national policy-makers on the vulnerability of afrormosia and to propose appropriate measures that can avoid future unsustainable/unregulated exploitation activities/Pericopsis elata est une espèce forestière africaine commercialisée sous les noms d’afrormosia ou d’assamela. Elle est une des principales espèces exploitées pour le bois d’œuvre en République Démocratique du Congo (RDC) et dans une moindre mesure au Cameroun et au Congo. Elle est au centre de nombreuses polémiques, notamment dans l’Union européenne, en ce qui concerne la durabilité de son exploitation. C’est une des rares espèces commerciales productrice de bois d’œuvre listée, depuis 1992, dans l’Annexe II de la CITES (Convention sur le commerce international des espèces en danger d’extinction) qui spécifie que « L'exportation d'un spécimen d'une espèce inscrite à l'Annexe II nécessite la délivrance et la présentation préalables d'un permis d'exportation ». Les plus grandes réserves d’afrormosia se trouvent en RDC. Cette thèse de doctorat porte sur l’écologie de cet arbre et sur son comportement vis-à-vis de l’exploitation forestière. Elle permet d’informer les organismes internationaux comme la CITES et les décideurs nationaux sur la vulnérabilité de l’afrormosia et de proposer des mesures à prendre pour que l’espèce ne soit pas menacée par une exploitation mal conduite et non régulée / Doctorat en Sciences / info:eu-repo/semantics/nonPublished

Des changements de croissance ont été documentés pour le XXe siècle dans de nombreuses régions en Europe. Cependant une évaluation exhaustive des changements de productivité, à une large échelle géographique, avec une analyse de leur hétérogénéité spatiale et de la diversité interspécifique de la réponse fait encore défaut. L'objectif de cette thèse est d'évaluer les changements récents de la productivité forestière aux échelles nationale, régionale et locale en France, et de rechercher leurs causes environnementales, à partir d'une approche de modélisation statistique de l'accroissement en surface terrière du peuplement (∆G) et d'indicateurs environnementaux. Nous avons utilisé les données de l'inventaire forestier national français pour 8 espèces dont la niche écologique et la distribution diffèrent (Fagus sylvatica, Quercus robur, Quercus petraea, Quercus pubescens, Picea abies, Abies alba, Pinus sylvestris and Pinus halepensis), observées en peuplements purs et réguliers. Nous présentons les facteurs ayant un effet sur la productivité des différentes espèces à l'échelle nationale, ainsi que des cartes de productivité suggérant que l'aire de distribution des espèces n'est pas toujours limitée par les conditions environnementales. Entre 1980 et 2005, nous observons des tendances positives, modales ou non significatives de la productivité pour toutes les espèces à l'exception des deux espèces méditerranéennes dont la productivité a diminué, soulignant ainsi la variabilité interspécifique de ces changements. Nous observons également de fortes variations spatiales des changements de productivité, autant dans leur intensité que dans leur signe, aux échelles régionale et intra-régionale. Ces résultats remettent en question la pertinence d'une évaluation moyenne à large échelle et soulignent le caractère contextuel des estimations. Nous mettons en évidence le rôle du réchauffement climatique récent dans les tendances observées. Ce travail fournit une évaluation plurispécifique et multi-échelle de la réaction de la productivité des espèces arborées à un environnement changeant. Nous avons souligné le caractère spécifique des changements de productivité et leur caractère contextuel, du fait de différences dans l'autécologie des espèces et de variations spatiales des facteurs limitants. Une étude approfondie de l'effet des facteurs environnementaux et de leurs interactions complexes est nécessaire pour la prédiction de la productivité future des espèces. / Growth trends have been reported in many regions of Europe over the twentieth century. However, an integrated assessment of productivity changes, including focus on a wide geographical scale, analysis of spatial heterogeneity, and the inter-specific diversity of growth responses is still lacking. The aim of this Ph.D work was to assess recent changes in forest productivity on a national, regional and local scale in France, and to investigate their potential environmental causes, based on statistical modeling approaches of stand basal area increment (BAI), and environmental indicators. We used the French NFI data for 8 species of contrasted ecological niches and distributions (Fagus sylvatica, Quercus robur, Quercus petraea, Quercus pubescens, Picea abies, Abies alba, Pinus sylvestris and Pinus halepensis), taken in pure and even-aged stands. We identified the main factors influencing tree species productivity on a national scale, and produced productivity maps suggesting that species distribution ranges are not always limited by environmental conditions. Between 1980 and 2005, the productivity trends reported were positive, modal or non-significant for all species, except the two Mediterranean species for which productivity decreased, highlighting inter-specific differences in these changes. We observed strong variations of productivity changes, both in intensity and sign, on a regional and intra-regional scale. These results question the relevance of wide-scale average assessments and highlight their context-dependence. The role of recent climatic warming in featuring the BAI trends was highlighted. This work provides an enriched scale- and species-dependent assessment of tree species reaction to a changing environment. We emphasized the species- and context dependence of productivity changes, due to differences in species autecology and spatial variations in the limiting factors. Further focus on the effect of environmental factors and their complex interactions is needed for the prediction of species future productivity.