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This thesis is prepared in three parts; the first part is a study of the ant species of the southern Carnarvon Basin, which was undertaken in order to determine the patterns of ant species distribution in this arid zone area. The distribution patterns were looked at in terms of biogeographical regions and they demonstrated the transitional nature of this particular area. Recommendations to alter the border between the South-west Province and the Eremaean Province were supported. The next chapter of this thesis analysed ant species from long unburnt and burnt areas of three main vegetation types (two Triodia species grasslands and Acacia aneura woodlands) in the Gibson Desert Nature Reserve. This study was carried out to observe the recovery of ant populations after fire. The results provided further evidence that invertebrates are measurably impacted by fire in the arid zone. The final chapter is a comparison of these two arid zone studies with six other ant community studies from throughout Western Australia. It demonstrated the uniqueness of some arid zone sites as well as related each study to each other according to their ant communities.

Invasive weeds inflict significant harm on native species, ecosystem processes, and natural disturbance regimes. When managing these weed threats, some of the most useful tools are the outputs of predictive distribution models. As they supplement existing distribution data to assess where in the landscape is most susceptible to weed invasion, they allow for more efficient weed management because the areas most suited to weed species may be targeted for control. This research develops a habitat suitability model for the weed lantana (Lantana camara L. sensu lato) in a portion of the Greater Blue Mountains World Heritage Area at present and under forecast warmer climates. A generalised additive model (GAM) is used, which fits the regression curve used for prediction to the calibration data themselves and allows for an exploration of which environmental conditions favour lantana as well as where in the landscape is most suitable for the weed. Temperature was positively correlated with suitable habitat and explained over 90% of the variation in lantana presence predicted by the model. 15% of the study area was found to be suitable for lantana at present, with this figure reaching 58% after a simulated 3??C rise in temperature. Mapping habitat suitability across the study area allowed for the identification of five distinct pathways for lantana to further invade the Blue Mountains. Responding to calls for the integration of weed management with biodiversity conservation, the research also integrates the habitat suitability model with information regarding the distribution of vegetation communities and endangered species in the Blue Mountains. Thirteen native vegetation communities were found to have more than 20% suitable habitat for lantana at present, and an additional three contained more than 80% suitable habitat after a simulated 3??C rise in temperature. Five of these communities are listed as threatened under relevant legislation and harbour at least 27 endangered species, placing additional urgency on their conservation. This research has successfully used modelling techniques to identify areas for targeted weed management integrated with biodiversity conservation. The methods are easily adaptable to other weeds and regions and could thus be used to illustrate the comprehensive threat weeds pose to Australia???s biodiversity.

Invasive weeds inflict significant harm on native species, ecosystem processes, and natural disturbance regimes. When managing these weed threats, some of the most useful tools are the outputs of predictive distribution models. As they supplement existing distribution data to assess where in the landscape is most susceptible to weed invasion, they allow for more efficient weed management because the areas most suited to weed species may be targeted for control. This research develops a habitat suitability model for the weed lantana (Lantana camara L. sensu lato) in a portion of the Greater Blue Mountains World Heritage Area at present and under forecast warmer climates. A generalised additive model (GAM) is used, which fits the regression curve used for prediction to the calibration data themselves and allows for an exploration of which environmental conditions favour lantana as well as where in the landscape is most suitable for the weed. Temperature was positively correlated with suitable habitat and explained over 90% of the variation in lantana presence predicted by the model. 15% of the study area was found to be suitable for lantana at present, with this figure reaching 58% after a simulated 3??C rise in temperature. Mapping habitat suitability across the study area allowed for the identification of five distinct pathways for lantana to further invade the Blue Mountains. Responding to calls for the integration of weed management with biodiversity conservation, the research also integrates the habitat suitability model with information regarding the distribution of vegetation communities and endangered species in the Blue Mountains. Thirteen native vegetation communities were found to have more than 20% suitable habitat for lantana at present, and an additional three contained more than 80% suitable habitat after a simulated 3??C rise in temperature. Five of these communities are listed as threatened under relevant legislation and harbour at least 27 endangered species, placing additional urgency on their conservation. This research has successfully used modelling techniques to identify areas for targeted weed management integrated with biodiversity conservation. The methods are easily adaptable to other weeds and regions and could thus be used to illustrate the comprehensive threat weeds pose to Australia???s biodiversity.

Invasive weeds inflict significant harm on native species, ecosystem processes, and natural disturbance regimes. When managing these weed threats, some of the most useful tools are the outputs of predictive distribution models. As they supplement existing distribution data to assess where in the landscape is most susceptible to weed invasion, they allow for more efficient weed management because the areas most suited to weed species may be targeted for control. This research develops a habitat suitability model for the weed lantana (Lantana camara L. sensu lato) in a portion of the Greater Blue Mountains World Heritage Area at present and under forecast warmer climates. A generalised additive model (GAM) is used, which fits the regression curve used for prediction to the calibration data themselves and allows for an exploration of which environmental conditions favour lantana as well as where in the landscape is most suitable for the weed. Temperature was positively correlated with suitable habitat and explained over 90% of the variation in lantana presence predicted by the model. 15% of the study area was found to be suitable for lantana at present, with this figure reaching 58% after a simulated 3??C rise in temperature. Mapping habitat suitability across the study area allowed for the identification of five distinct pathways for lantana to further invade the Blue Mountains. Responding to calls for the integration of weed management with biodiversity conservation, the research also integrates the habitat suitability model with information regarding the distribution of vegetation communities and endangered species in the Blue Mountains. Thirteen native vegetation communities were found to have more than 20% suitable habitat for lantana at present, and an additional three contained more than 80% suitable habitat after a simulated 3??C rise in temperature. Five of these communities are listed as threatened under relevant legislation and harbour at least 27 endangered species, placing additional urgency on their conservation. This research has successfully used modelling techniques to identify areas for targeted weed management integrated with biodiversity conservation. The methods are easily adaptable to other weeds and regions and could thus be used to illustrate the comprehensive threat weeds pose to Australia???s biodiversity.

L’intensification des pratiques agricoles de ces dernières décennies a engendré des modifications profondes des écosystèmes agricoles. Les oiseaux prairiaux sont particulièrement concernés par ces changements et ont fortement décliné. La mise en place de Mesures Agro-Environnementales (MAE) n’ont pas permis d’enrayer ce déclin et une évaluation de leur efficacité passe au préalable par une compréhension affinée des réponses écologiques des espèces dans l’écosystème considéré. Nous avons ainsi tenté de mieux comprendre la distribution et la sélection d’habitat des oiseaux prairiaux dans les plaines d’inondation du bassin de la Loire dans l’ouest de la France. Cette étude visait à construire et à tester à l’échelle de la zone d’étude des prédicteurs environnementaux pertinents d’humidité, de climat, de végétation et de paysage. Il a ainsi été possible d’établir la réponse des espèces à ces prédicteurs et de construire des modèles de distribution locaux. Cette étude a permis de confirmer le rôle structurant du gradient d’humidité pour les populations d’oiseaux prairiaux en plaine alluviale. Ce gradient conditionne la qualité de l’habitat pour ces espèces en contrôlant notamment la végétation présente. Il contrôle en outre la phénologie des fauches qui est le facteur-clé dont dépend le succès reproducteur. Enfin, il est largement déterminé par la susceptibilité à l’inondation, qui peut affecter la distribution lorsqu’elle intervient au printemps induisant ainsi un découplage spatial entre les MAE et la distribution des espèces prairiales en milieu alluvial. Nous avons également mis en évidence l’évitement par les oiseaux prairiaux du bocage qui concentre par ailleurs des enjeux importants de conservation de la biodiversité. Enfin, nous avons utilisé les prédicteurs environnementaux pour modéliser la distribution des oiseaux prairiaux lesquels mettent en évidence des différences d’utilisation de l’habitat prairial entre les espèces. Ces résultats mettent en avant la nécessité de redéfinir les priorités de conservation à l’échelle du paysage. Ils pourraient également être pris en considération pour améliorer l’efficacité des MAE. / The intensification of agricultural practices in the last decades profoundly changed agricultural ecosystems. Grassland birds are particularly affected by these changes and have been declining sharply. The implementation of Agro-Environmental Schemes (AES) failed to halt this decline. Assessing their effectiveness requires a better understanding of the ecological responses of species in the ecosystem. We attempted to quantify and analyze the distribution and habitat selection of grassland birds in the floodplains of the Loire basin in Western France. This study aimed at building and testing relevant environmental predictors of moisture, climate, vegetation and landscape. Then, we established species response to these predictors and built local distribution models. This study confirmed the prominent rôle of moisture gradient for grassland bird populations in floodplains. The location on the gradient determines habitat quality for these species especially by affecting vegetation composition. It also controls the phenology of mowing, a key factor for reproductive success. Finally, this gradient is largely determined by flooding susceptibility, which may affect bird distribution when flood occurs in spring. In such years, we observed a spatial mismatch between AES and grassland bird distributions in floodplain. We also highlighted the avoidance of hedgerows by grassland birds, which stresses the incompatibility at fine scale between two objects of biodiversity conservation. Finally, we used the environmental predictors to model the distributions the main grassland birds, which models highlighted differences in habitat use between grassland species. These results emphasize the need to redefine the priorities of conservation at the landscape scale. They could also be considered to improve the efficiency of AES

Invasive species are organisms whose introduction and spread in exotic ranges result in a multitude of ecological impacts. Understanding the factors that constrain the exotic distributions of invasive species is of considerable interest. Biotic associations formed with taxa in the invaded community may be particularly important in shaping invader distributions. These associations emerge from interactions between the traits of the invasive species and some subset of the traits present in the invaded community. Focusing on how organism traits influence the outcomes of biotic interactions may inform predictions of invader distributions. This kind of trait-based approach may be most easily applied to systems where invaders specialize on particular hosts because such associations imply a close correspondence between the traits of the invader and hosts. This dissertation focuses on the South American cactus moth (Cactoblastis cactorum, Lepidoptera: Pyralidae), an invasive consumer in North America whose larvae infest prickly-pear cacti (Opuntia spp.). Chapter One is a brief introduction providing background and context to the presented research. In Chapter Two, I quantify Opuntia morphological and tissue macronutrient traits hypothesized to correlate with patterns of C. cactorum host use. Tissue macronutrient traits appear important in predicting C. cactorum infestation whereas a model containing Opuntia morphological traits had poor predictive ability. Chapter Three describes a method that uses host Opuntia identity and availability to estimate habitat suitability in order to predict the North American distribution of C. cactorum. I then simulate C. cactorum dispersal relative to scenarios of habitat suitability and Opuntia availability. Chapter Four alters the model in Chapter Three so that habitat suitability for C. cactorum is determined by the availability of trait-based groupings of Opuntia hosts. I then simulate C. cactorum dispersal via a different method from that described in Chapter Three. In Chapters Three and Four, I evaluate the degree of similarity among model predictions and the relative contribution of modeling constraints in generating variation in this similarity. Chapters Three and Four predictions were most affected by estimates of abiotic suitability and dispersal constraints, respectively. Chapter Five is a short summary of my results and a discussion of their more general applicability.

The Clinch Dace Chrosomus sp. cf. saylori is a species of minnow known from only two counties in Virginia. Prior surveys established the species' presence in just eight tributaries to the upper Clinch River. A management plan, which should include both population monitoring and habitat restoration, is still lacking for the species. Population monitoring must balance high detection probability with low risk of injury to captured individuals. I sampled 98 sites in 2014 and 2015 within the putative range of Clinch Dace to refine estimates of its distribution. I sampled 70 of the 98 sites with multiple gears and replication in an occupancy modeling framework. Clinch Dace occupied low-gradient headwater streams with relatively low conductivity in forested watersheds. My surveys uncovered two new tributaries occupied by Clinch Dace, and I was unable to find Clinch Dace in two historically occupied streams. Species detection probability was higher with backpack electrofishing than minnow trapping. N-mixture models suggest that Clinch Dace are more abundant in watersheds with high forest cover although forest cover is highly correlated spatially in the nested stream network. Density estimates from mark-recapture sampling suggest that Clinch Dace occur at low densities in approximately 31.5 km of headwater streams. The mean estimate of global population size was 6,706 individuals. Some populations could be affected by low genetic diversity. I conclude by developing a prioritization framework for restoration and protection of 15 candidate conservation areas. Managers should work with private landowners to implement best management practices in high priority watersheds. / Master of Science

This thesis explores some important practical considerations concerning the use of species distribution models in marine conservation planning. Using geo-referenced gorgonian distribution data, together with explanatory environmental variables, predictive models have been used to map the spatial distribution of suitable gorgonian (sea fan) habitat in two study sites; Hatton Bank, in the Northeast Atlantic, and Lyme Bay on the south coast of Devon. Generalized Linear Models (GLMs), Generalized Additive Models (GAMs) and a Maximum Entropy (Maxent) model have been used to support critical investigation into important model considerations that have received inadequate attention in the marine environment. The influence of environmental data resolution on model performance has been explored with specific reference to available datasets in the nearshore and offshore environments. The transferability of deep-sea models has been similarly appraised, with recommendations as to the appropriate use of transferred models. Investigating these practical issues will allow managers to make informed decisions with respect to the best and most appropriate use of existing data. This study has also used novel approaches and investigated their suitability for marine conservation planning, including the use of model classification error in the spatial prioritisation of monitoring sites, and the adaptation of an existing presence-only modelling method to include absence data. Together, these studies contribute both practical recommendations for marine conservation planning and novel applications within the wider species distribution modelling discipline, and consider the implications of these developments for managers, to ensure the ongoing improvement and development of models to support conservation planning.

Florida scrub is a xeromorphic upland shrub community dominated by evergreen oaks that resprout after fire, occurring on moderately to excessively well-drained nutrient-poor sand. Scrub is home to several threatened and endangered animal species (e.g., Florida scrub-jay, gopher tortoise, and indigo snake) and rare and endemic plants. Urban development and agriculture has greatly reduced and fragmented scrub habitat, and because of this Florida scrub is considered one of the most endangered ecosystems in the United States. Climate change is a further threat to Florida scrub. Under a warmer and drier climate, scrub species will be exposed to more frequent and more severe droughts. In order to understand how scrub will respond to a changing climate, we must first have a better understanding of how scrub species respond to climate and water availability. In this dissertation, I use a combination of dendrochronology and plant physiological techniques to examine species responses to climate and water availability. In chapter two, I use dendrochronology to examine the importance of seasonal climate on growth of three co-occurring species in Florida scrub, myrtle oak (Quercus myrtifolia Willd.), Chapman oak (Quercus chapmanii Sarg.), and south Florida slash pine (Pinus elliottii Engelmann var. densa Little & K.W. Dorman). This is the first dendrochronology study on co-occurring scrub species. Therefore, my first goal was to ask whether Chapman oak and myrtle oak put on distinct annual rings with year to year variability that would enable successful crossdating. Because I found that each species does have annual rings that can be crossdated, my second goal was to ask how growth in each species responds to climate and its extremes, drought and extreme precipitation. Growth in both oaks was positively correlated with spring precipitation, while slash pine total and latewood growth was positively correlated with April and September precipitation. Slash pine earlywood growth was positively correlated associated with increased winter precipitation. In all three species, growth was sensitive to both annual and spring droughts. However, only slash pine exhibited increased growth with precipitation associated with tropical weather during July-September. Earlywood growth of slash pine was positively correlated with the Ni[ntilde]o 3.4 index: colder, wetter winters tended to be associated with increased earlywood growth. The between-species differences in response to seasonal climate may be due to differences in growth phenology. For both oaks, the climatic limiting factor was water availability in the spring, which is when the majority of radial growth occurs. By contrast, for slash pine, growth was limited by precipitation in the spring and late summer, its peak growth period. During the period for which we have a dendrochronological record (1920 to present), precipitation in April has become increasingly correlated with growth for all three species; as it has become the driest spring month during this period. In chapter three, I use dendrochronology to determine the climate-growth relationships of the dominant oak in Florida scrub, myrtle oak, for five sites occurring on three different scrub ridges in central Florida. My goals were twofold: 1) to ask whether the climate-growth responses of myrtle oak were robust across sites and 2) to ask how myrtle oak growth was affected by droughts (determined on both seasonal and annual basis). Myrtle oak growth increased with increased spring precipitation; temperature had little effect on myrtle oak growth. The growth response of myrtle oak to moisture availability (measured by the standardized precipitation index (SPI)) in March, April, May, and June, was robust across sites, with the exception of Malabar West. Myrtle oaks at Malabar West grew on poorly drained soils and were less responsive to precipitation and drought than were oaks growing on the other sites. March, April, May, and June SPI explained between 21.5 to 58.3% of the variation in myrtle oak growth for each site. Seasonal droughts explained more of the variation in growth than annual droughts. Spring droughts decreased myrtle oak growth at all sites, and drought during the previous summer decreased growth at Malabar West. Drought impacted growth for a single year; growth was normal or greater than normal during the year after drought. These results suggest that the timing of drought is important for myrtle oak growth, and that seasonal measures of drought are more important than annual measures of drought for determining growth impacts. In chapter four, I examine how the distribution and physiological functioning of scrub species vary along the ridge-swale topography at the Kennedy Space Center. Climatic factors often limit species distributions and plant physiological functions over large elevation gradients. However, on small elevation gradients, hydrologic variation may have strong effects on the distribution of species and the physiological function within a species. I used point-intercept sampling along a ridge-swale gradient at Kennedy Space Center on Merritt Island, Florida, to study how species distribution varied over a 1.2 m elevation gradient. Data from water monitoring wells along the elevation gradient were used to ask whether elevation may serve as a proxy for depth to water table. Elevation served as a good proxy for depth to water table; water table depth increased with elevation. I focused especially on understanding how the distribution and physiological functioning of three co-occurring Florida scrub oak species (Chapman oak, sand live oak (Quercus geminata) and myrtle oak) varied along the elevation gradient. Cover of all three scrub oaks increased with increasing elevation. Only sand live oak exhibited differences in physiological functioning along the elevation gradient; individuals at lower elevations were more sensitive to drought than individuals on the ridge. All three oaks exhibited stomatal regulation of water use efficiency drought. Chapman oak did not exhibit decreased photosynthetic activity during drought. Leaf phenology may play a role in the different responses to drought exhibited.