Dissertations / Theses on the topic 'Terrestrial ecology'

According to the exploitation ecosystem hypothesis (EEH), terrestrial ecosystems are characterized by well defined trophic levels and strong trophic interactions with community level tropic cascades. In unproductive terrestrial habitats as tundra heaths, the energy shunt from litter and apparent competition between herbivores and detritivores are expected to be important for the structure and dynamics of the invertebrate community. The aim of this study was to test this hypothesis by investigating if plant litter accumulation was affecting the invertebrate community on a nutrient-poor tundra heath. The study was performed during one summer on the highland part of Joatka research area, in the north of Norway.

The experimental area included 16 plots (100 m² each), of which 12 had been littermanipulated. On four plots the amount of litter was increased by 100 %, on four by 200 % and on four by 400 %. Four plots were untreated and used as control plots. Invertebrates were collected by emergence traps (which cover an area of 1 m²), one trap on each plot and one pitfall trap inside each emergence trap. During the study period, traps were emptied and moved twice, resulting in three sampling periods. The invertebrates collected were counted and their length was measured, than all invertebrates were sorted into taxa and trophic guilds. During the study period, herbivore grazing damage was investigated on all 16 experimental plots, signs of herbivores on leaves of vascular plants in an area covering 3 m2 per plot were noted, for every leaf with signs of herbivory the percentage of leaf area removed was estimated.

Plant biomass and plant species composition were estimated in all experimental plots by harvesting above-ground plant parts. In each plot, two squares were randomly chosen and all biomass in this square was collected. Plant biomass was sorted in to following groups: dwarf birch, billberry, Salix herbacea, Salix spp, graminoids, herbs, lichens, mosses and dwarf shrub. Before weighing the plant material, it was stored in paper bags at room temperature and then dried for 48 h at 40°C. In order to detect fertilisation effects, all bilberry shoots that had been produced during the actual summer were separately weighted when analyzing the plant biomass.

The result showed that the invertebrate community in this area is dominated by carnivores while detritivores, parasitoids and herbivores are quite rare, this was in accordance with previous studies made in the area. Litter manipulation did not create any significant variation in the community structure, but there was a slight tendency that carnivore biomass increased and biomass of herbivores decreased when litter was added to the system. In contrary to this,

gracing activity especially on dwarf willow (Salix herbacea) increased in plots were 100 % and 200 % more litter was added. There is a positive correlation between biomass of herbivores and detritivores but the reason for this seems unclear. No fertilisation effect was detected in litter manipulated plots. The structure and dynamics of the actual community could not be described by the food web theory EEH and energy shunt from litter and apparent competition between herbivores and detritivores. It seems to be several complicating factors to take into consideration when describing this community.

As climate-driven changes in phenology are becoming more apparent, the need to quantify these changes is increasing. An important challenge in detecting phenological changes is that between-year variation in phenology is large. Between-year variation determines the statistical power of comparisons between contemporary and historical observations. For 44 plant species with different distributions across Sweden, geographicand inter-specific differences in between-year variation in different phenophases (budburst, flowering, ripe fruits, and leaf fall) was studied. I also modeled and evaluated theresponse of bud burst, and flowering, to temperature using three different temperature sum models over a latitudinal gradient. The data used was a sub-sample from a dataset collected by a Swedish nation-wide phenology network between 1873-1917. In agreement with previous studies, I show that early spring phases have a higher variability than phases occurring later in the season. However, the relation between onset and variation was not monotonically decreasing. In the geographical analyses, a unimodal relation between between-year variation and latitude was found, that is, the between-year variation decreased along the latitudinal gradient for early- and late season events, while it increased over latitude for summer events. These patterns are, to a great extent, reflections of patterns in air temperatures which is discussed using meteorological data from adjacent climate stations. Models were evaluated using Akaike's Information Criterion, and in 60% of all fits, the Spring warming CF2 model (SWCF2; the model with the least number of parameters) was selected as the best model to describe the data. For Sorbus aucuparia bud burst, in the two parameter model SWCF2, both parameters (threshold temperature andtemperature sum) correlated with latitude. However, future analysis using more locations and a wider span of species will be needed to understand the generality in these findings. In conclusion, future efforts to detect and quantify phenological changes need to consider differences in between-year phenological variability along geographical gradients and among species with different phenology.

Habitat loss is the primary driver of global amphibian declines and thus preserving habitat is our best hope for preserving species at risk. The habitat needs of amphibians are complex due to terrestrial and aquatic requirements throughout their life history. Many pond breeding amphibians spend the majority of their life cycle within terrestrial environments and thus terrestrial habitats are critical to their persistence. Cryptic and fossorial behavior makes observations of amphibians in terrestrial habitats difficult. Our knowledge of the terrestrial ecology of amphibians is therefore incredibly limited. I review the literature on habitat loss, amphibian declines and terrestrial habitat use by amphibians with specific attention to refuge seeking behavior (CHAPTER ONE). I used radio-tracking to investigate the behavior of Fowler's toads (Bufo fowleri) in the beach dune ecosystem of Long Point, Ontario. Refuge seeking behavior by these animals is associated with specific components of the dunes and is predictable based on elevation, slope and distance from the lakeshore. Refuge sites placement is not random, but instead represent a trade-off between risk and reward (CHAPTER TWO). Philopatry in Fowler's Toads is driven by fidelity to refugia. These locations are used repeatedly on consecutive days, and even when they are not new sites within 10 meters of the previous day's refuge are most often chosen. Occasionally, however toads relocate their refuge sites as much as 700 m overnight (CHAPTER THREE). This contributes to the wide variation in the home range sizes of Fowler's Toads, as does method of calculation and search effort, while there is little apparent influence of intrinsic biological factors. The effect of search effort on range size is reduced in robust location data sets with more than thirty locations for each animal. A minimum home range estimate of 3517m2 is suggested under the caveat that range sizes may have no hard upper limit (CHAPTER FOUR).
La perte d'habitat est le principal facteur responsable du déclin des amphibiens à l'échelle mondiale. La préservation de leur habitat représente donc le meilleur espoir pour la conservation de ces espèces en péril. Les amphibiens ont des besoins en complexes en matière d'habitat, car leur cycle de vie comprend des exigences terrestres ainsi qu'aquatiques. Plusieurs amphibiens qui se reproduisent dans des étangs passent la majorité de leur vie dans des environnements terrestres, ces derniers sont donc essentiels à leur résilience. Leurs comportements fouisseur et cryptique rendent les amphibiens difficiles à observer dans leurs habitats terrestres. En conséquence, notre connaissance de l'écologie terrestre des amphibiens est très limitée. Je passe en revue la littérature scientifique sur la perte d'habitat, le déclin des amphibiens et l'utilisation d'habitats terrestres par les amphibiens avec une attention particulière à la recherche de refuges (CHAPITRE UN). J'ai utilisé le pistage radioélectrique pour étudier le comportement des crapauds de Fowler (Bufo fowleri) dans l'écosystème de dunes de la plage de Long Point, en Ontario. La recherche de refuge par ces animaux est associée à des composants spécifiques des dunes et est prévisible selon l'élévation, la pente et la distance du bord du lac. L'emplacement du refuge n'est pas aléatoire, mais représente plutôt un compromis entre risque et récompense (CHAPITRE DEUX). La philopatrie chez les crapauds de Fowler est due à la fidélité aux refuges. Ces endroits sont utilisés de façon répétée sur plusieurs jours consécutifs ; même lorsqu'ils sont abandonnés, les crapauds choisissent le plus souvent un nouveau site à moins de 10 mètres du refuge de la journée précédente. A l'occasion, cependant, les crapauds peuvent délocaliser leurs sites de refuge jusqu'à 700 m d'une nuit à l'autre (CHAPITRE TROIS). Cela contribue à la grande variation dans le calcul de la taille du territoire des crapauds de Fowler. Les méthodes d'évaluation et l'effort de recherche contribuent aussi à cette variation, alors qu'il y a peu d'influence apparente des facteurs biologiques intrinsèques. De plus, l'effet de l'effort de recherche sur la taille du territoire est réduit lorsque les données de localisation sont robustes et comprennent plus de trente sites par animal. Une estimation de taille minimale du territoire des crapauds de Fowler de 3517 m2 est suggérée ici, sous la réserve que l'aire totale de répartition peut ne pas avoir de limite supérieure (CHAPITRE QUATRE).

Isoprene (2-methyl 1, 3-butadiene) is the most abundant non-methane BVOC (biogenic volatile organic compound) released into the atmosphere. Terrestrial plants are the primary producers of isoprene and release 500-750 million tonnes of isoprene per year, to protect themselves from abiotic environmental stresses such as heat and reactive oxygen species. Many studies have explored isoprene production but very little is known about consumption of isoprene by microbes. Cleveland and Yavitt in 1998 (Cleveland and Yavitt 1998), and more recently Khawand et al. 2016 (Khawand et al. 2016), demonstrated that microbes isolated from terrestrial environments are capable of using isoprene as sole carbon and energy source. By applying cultivation-dependent and cultivation-independent techniques, such as DNA Stable Isotope Probing (Dumont and Murrell 2005), my objective was to determine the distribution, diversity and activity of isoprene-degrading bacteria in the terrestrial environment. Isoprene-degrading microbes were enriched by adding 13 to 50 ppm isoprene to microcosms using topsoil from a willow tree and topsoil/leaves from an oil palm tree. DNA stable isotope probing, using 13C-labelled isoprene, assisted in revealing the diversity of active isoprene degraders by labelling organisms that incorporated the isoprene, directly or indirectly. PCR retrieval of partial 16S rRNA genes from this DNA revealed labelled members of the genera Ramlibacter, Variovorax, Rhodococcus and Methylibium, for willow soil, and Rhodococcus, Gordonia, Aquabacterium, Aquincola, Methylobacterium and members from the Sphingomonadaceae family, for the oil palm tree. Using cultivation-dependent methods I isolated seven phylogenetically different isoprene-utilizing bacteria of the genera Rhodococcus, Nocardioides and Variovorax from willow soil environment; another four phylogenetically different bacteria belonging to the genera Gordonia, Sphingopyxis and Sphingobacterium from the oil palm tree. Results suggest Rhodococcus is a cosmopolitan isoprene-degrader, present in a variety of environments, and different isoprene-degrading bacteria were found associated to willow and oil palm trees.

Freshwater and terrestrial ecosystems are tightly linked by food web interactions. Naturally occurring carbon and nitrogen stable isotopes provide a tool to quantify nutrient flows across ecological boundaries, however their application to freshwater-terrestrial systems has been limited. This thesis evaluated whether stable isotope analysis can be effective in differentiating freshwater and terrestrial vascular plants at the base of subarctic food webs and found freshwater plants to be consistently enriched in their isotopic signatures relative to terrestrial plants. Stable isotope approaches were then used to investigate spatial and temporal variability in the diet of a population of subarctic beavers (Castor canadensis). Freshwater macrophytes contributed more to the diets of beavers than previously reported. During the winter, beavers from pond habitats consumed more aquatic vegetation than beavers from stream habitats which relied more heavily on food hoards of terrestrial vegetation. Aquatic foraging may enable beavers to persist at the northern periphery of their range by reducing foraging pressure on the subarctic terrestrial ecosystem where their preferred tree species are scarce.
Les écosystèmes d'eau douce et terrestres sont liés par les interactions trophiques. Les isotopes stables naturels de carbone et d'azote offrent une méthode pour quantifier les transferts de nutriments entre les frontières écologiques, mais leurs applications aux systèmes d'eau douce-terrestres sont encore limitées. Cette thèse évalue l'efficacité des isotopes stables pour distinguer les plantes vasculaires d'eau douces et terrestres qui forment la base des chaînes alimentaires subarctiques. Nous avons trouvé qu'en général les plantes aquatiques avaient des signatures isotopiques enrichies par rapport aux plantes terrestres. Nous avons ensuite employé les techniques d'isotopes stables pour évaluer la variabilité spatiale et temporale dans le régime alimentaire d'une population de castors (Castor canadensis) subarctiques. Les macrophytes aquatiques semblent avoir une place plus importante dans le régime alimentaire des castors en comparaison avec la littérature disponible. Durant l'hiver, les castors qui habitaient les lacs ont consommé plus de végétation aquatique par rapport aux castors qui habitaient dans les rivières, ceux-ci comptant plutôt sur les provisions de végétation terrestre. L'accumulation de provisions constituées de plantes aquatiques peut permettre aux castors de persister à la limite de leurs aires de distribution où les arbres préférés des castors sont rares. Ainsi, ce phénomène pourrait réduire la pression des herbivores sur ces écosystèmes terrestres à faible productivité.

The present study examines the cycling of elements in the biosphere. The first chapter proposes a theoretical framework for this cycling based on both metal/ligand theory and mass balance studies. Empirical modelling serves as an alternative and complement to mass balance studies in predicting the export of elements from watersheds. Watershed output (export per unit area per unit of time) is predicted using atmospheric deposition rates, an element bonding strength index, the watershed area and a forest classification (deciduous vs coniferous). Finally the last chapter examines, in a speculative fashion, the partitioning of elements between the atmosphere and hydrosphere as a function of element behaviour and discusses the ecological consequences of human activity on this partitioning.

Tetrodotoxin (TTX) is a potent neurotoxin that acts by blocking the pore region of voltage-gated sodium channels in nerve and muscle tissue. This causes paralysis, and often death due to asphyxiation. Interestingly, TTX is found in an array of organisms ranging from bacterial species to vertebrates. Further, TTX is found in both aquatic and terrestrial environments. This range of taxa and environments has led to three common lines of study for ecological research on this toxin: production, predation, and identification of novel TTX bearing taxa. I began my research by also refining a Competitive Inhibition Enzymatic Immunoassay technique for fast, easy, and inexpensive quantification of TTX. I then focused on the three previously mentioned areas of research. Female newts (Taricha granulosa) are known to endow their eggs with TTX in order to protect them from predation. I looked at whether females allocated TTX to their eggs evenly over three years in captivity and compared those levels to TTX levels in eggs directly after capture. I found that eggs had lower levels of TTX following initial capture, but those levels did not change over the next three years. This provides evidence that TTX is endogenously produced in this species. Because of the high levels of TTX in newts, there are few known predators. I observed river otters feeding on newts in a high elevation lake in Oregon. I found that these newts have very low levels of TTX, and that in general high elevation populations in Oregon have low levels of TTX relative to low elevation populations. Finally, I documented TTX in two species of terrestrial flatworm (Bipalium adventitium and Bipalium kewense). Tetrodotoxin has never before been identified in a terrestrial invertebrate species. Further, I found evidence that suggests that TTX is used for both defense and prey capture in these worms. These studies add to our understanding of the evolution of TTX and how it influences interactions between organisms and their biotic and abiotic environments.

Todo en la tierra es química. Esta afirmación tiene profundas implicaciones para las interacciones ecológicas. Los organismos vivos promueven y controlan flujos de materia y energía entre la atmosfera, hidrosfera y litosfera; modificando la composición química de la tierra de muchas maneras diferentes. La estequiometría ecológica estudia el balance y el papel de múltiples elementos químicos en las interacciones ecológicas y nos ayuda a entender patrones y procesos en la naturaleza. Representa el enlace entre la biogeoquímica y el funcionamiento de los ecosistemas, permitiéndonos describir procesos a todos los niveles de organización biológica, desde estructuras sub-celulares a ecosistemas. En esta Tesis he usado la estequiometría ecológica para describir procesos a nivel de organismo y ecosistema en tres condiciones ambientales terrestres diferentes. La estequiometría de los autótrofos se establece cuando estos usan luz para fijar carbono (C) y simultáneamente asimilan nutrientes. Las plantas son capaces de almacenar nutrientes en la vacuola intracelular y en diferentes órganos, lo que hace que su estequiometría sea muy flexible (baja homeostasis) y se adapten a diferentes ambientes, incluyendo condiciones del suelo limitantes para el desarrollo de las plantas. También, la interacción planta suelo se puede explorar a través de la estequiometría foliar, ya que se ha demostrado en todos los ecosistemas terrestres que el N:P foliar esta correlacionado positivamente con el N:P del suelo, sugiriendo que es un buen indicador de la disponibilidad de nutrientes. Las adaptaciones de las plantas a condiciones limitantes de nutrientes en el suelo son comunes en todos los ecosistemas terrestres, como es la fijación de nitrógeno, la asociación con micorrizas, producción de fosfatasas o la reabsorción de nutrientes desde las hojas senescentes para el reciclado interno de nutrientes. La composición elemental de las especies es afectada por esas interacciones abióticas y bióticas, y el intercambio de elementos químicos entre las especies y el espacio abiótico determinaran la composición elemental de las diferentes partes del ecosistema. En el Capítulo 2 exploramos el efecto biótico de la composición de las comunidades sobre la composición química foliar de distintas especies vegetales, a través del nicho biogeoquímico de cada especie. Encontramos que cada especie presenta su propio nicho biogeoquímico y fueron capaces de reajustar su composición química foliar en respuesta a las diferentes condiciones bióticas. Concluimos que las plantas pueden reajustar su composición elemental foliar cuando crecen en comunidades con diferente composición de plantas, a través del desplazamiento del nicho biogeoquímico, sugiriendo un uso diferencial de los recursos cuando los patrones de coexistencia cambian. En el Capítulo 3 hemos explorado el cambio en la composición química del sistema planta-suelo debido a la expansión de arbustos en los pastizales subalpinos del Pirineo. Esta expansión representa la transición desde pastizales puros a matorrales. Los pastizales son un ecosistema dominado por especies de ciclo de vida corto, rápido intercambio de nutrientes entre los compartimientos planta-suelo, altas concentraciones de nitrógeno (N), fósforo (P) y potasio (K) en el sistema planta-suelo, con alta productividad pero capacidad limitada de acumulación de biomasa. En cambio, los matorrales se caracterizan por ser un ecosistema dominado por especies de ciclo de vida largo, con estrategias más conservativas, con un intercambio de nutrientes más lento (relación de C:nutrientes altos en la biomasa aérea y baja concentración de N y P en el sistema planta-suelo) y mayor almacenamiento de nutrientes en la biomasa aérea de las plantas. La matorralización incrementa la dependencia de la adquisición de nutrientes como el N a través de micorrizas desde los pastizales puros a matorrales. Todos los cambios en el almacenamiento y composición elemental del sistema planta-suelo a lo largo de la sucesión desde pastizales a matorrales sugiere una desaceleración del ciclo biogeoquímico en las áreas montañosas donde la expansión de arbustos está presente. En el Capítulo 4, describimos la distribución de C y los nutrientes más importantes para el desarrollo de las plantas (N, P, K) en el sistema planta-suelo de bosques tropicales maduros en suelos pobres de la Guyana Francesa. También estudiamos el proceso de reabsorción de nutrientes desde las hojas senescentes, un mecanismo de nutrición de las plantas para evitar la perdida de nutrientes poco estudiado en este ecosistema. Nuestros resultados muestran que el P es el elemento más escaso presente en hojas, hojarasca y suelo. Las eficiencias de reabsorción de K y P fueron más altas que la de N y la estacionalidad solo afecto la reabsorción de K. La reabsorción de P fue la única que mostró una correlación, aunque débil, con el P en el suelo (total y disponible). Las relaciones entre la reabsorción de nutrientes y los rasgos funcionales de las especies (tasa de crecimiento, densidad de madera, diámetro a la altura del pecho y el área foliar específica) fueron débiles y variaron dependiendo del nutriente, en tanto que la relación filogenética no explica la variabilidad en las eficiencias de reabsorción de nutrientes de las especies. Nuestros resultados sugieren que la alta reabsorción de K y P desde las hojas senescentes es una estrategia adaptativa de las especies que les permite lidiar con la escasez de estos nutrientes en el suelo. Asimismo, el nivel de inmovilización de los nutrientes en los compuestos foliares (N > P > K) parece determinar significativamente el proceso de reabsorción. Concluimos que la reabsorción de nutrientes desde las hojas senescentes es un proceso clave de las plantas para la conservación de nutrientes en los bosques tropicales de la Guyana Francesa, especialmente para K y P, elementos que presentan una disponibilidad baja en el suelo, y esta depende principalmente del material parental y del proceso de lixiviación. En resumen, en esta Tesis hemos demostrado como la composición elemental del sistema planta-suelo refleja procesos e interacciones ecológicas, como son las interacciones intra e inter específica entre plantas (Capítulo 2), procesos fisiológicos poco estudiados en las plantas como la reabsorción de nutrientes (Capítulo 4) y la importancia de los estudios de estequiometría para describir cambios a nivel de ecosistema y predecir escenarios futuros (Capítulo 3). Estos estudios aportan nuevos conocimientos en el campo de la estequiometría ecológica y resaltan la importancia de este enfoque en los estudios ecológicos.
Everything on Earth is based on chemistry. This statement has profound implications for ecological interactions. Living organisms generate and control fluxes of energy and matter among the atmosphere, lithosphere and the hydrosphere, shaping the chemistry of the Earth in many different ways. Ecological stoichiometry aims to explore the balance and role of multiple chemical elements in ecological interactions and help us to understand patterns and processes in nature. It represents the link between the biogeochemistry and the ecosystems’ function and allows to describe processes across different levels of biological organization, from cellular structures to ecosystems. In this Thesis I use ecological stoichiometry to describe processes at organism and ecosystem levels in three contrasting terrestrial environment conditions. Autotrophs’ stoichiometry is established when these organism use light to fix carbon (C) and simultaneously assimilate nutrients. Plants are able to store nutrients in the cells’ vacuole and in different organs, which make them highly flexible (less homeostatic) in terms of their elemental composition. This feature explains the high adaptability of plants to different environments, including soil nutrient limitation conditions. Furthermore, plant-soil interaction could be explored through the foliar stoichiometry, because it has been shown that the foliar N:P is positive correlated with the N:P of soil in all terrestrial ecosystem, suggesting that foliar stoichiometry is a good indicator of the resource availability. Plant adaptations to soil nutrient limiting conditions are quite common in all terrestrial ecosystems, such as nitrogen fixation, mycorrhiza association, production of phosphatases and nutrient resorption before leave abscission. The species’ chemical composition is affected by all these abiotic and biotic interactions, and these exchange of chemical elements between the species and the abiotic part of the system determine the elemental composition of different components of the ecosystems. In Chapter 2, we explore the biotic effect of the community composition on the species foliar stoichiometry, taken as a proxy of the species’ biogeochemical niche. We found that each species has its own biogeochemical niche and is able to readjust its chemical composition in response to different biotic conditions. We conclude that plants can readjust their foliar element composition when they grow in communities with contrasting plant composition through the biogeochemical niche displacement, suggesting a differential use of the resources when the patterns of species coexistence change. In Chapter 3 we explore the plant-soil stoichiometry changes due the shrub expansion into the subalpine grassland in the Pyrenees. Shrub expansion had a clear impact on the plant-soil stoichiometry spectrum. This expansion represents the transition from pure grassland to shrubland. The grassland is an ecosystem dominated by short-lived species, fast nutrient turnover between the plant-soil compartments, high nitrogen (N), phosphorus (P) and potassium (K) concentrations in the plant-soil system, high productivity but low biomass stocks. The shrubland is an ecosystem characterized by long-lived species with more conservative strategy, slow nutrient turnover (low N and P concentrations in the plant-soil compartments, high C:nutrient ratios in the aboveground biomass) and high stocks of C and nutrients in the plant aboveground biomass. Shrub encroachment increase the acquisition of N through mycorrhizal associations. The changes in storage and elemental composition of the plant soil system along the succession from grassland to shrubland suggests that there is a slowdown of the biogeochemical cycle in the subalpine mountain areas where shrub encroachment occurred. In the Chapter 4, we describe the distribution of C and the most important nutrients for the plant development (N, P, K) in the plant and soil compartments in old-growth tropical forests growing in nutrient-poor soil in French Guiana. We also studied the nutrient resorption from senescent leaves, a poorly explored mechanism that plants use to avoid losing nutrients in this ecosystem. Our results showed that P was the scarcest nutrient in the leaf, leaf-litter and soil. Resorption efficiencies were higher for K and P than for N, and only K resorption efficiency was affected by seasonality. P resorption showed a negative and weak correlation with P in soil (total and available). Relationships between nutrient resorption and species functional characteristics (growth rate, wood density, diameter at breast height and specific leaf area) were weak and varied among the nutrients, and phylogenetic relatedness did not account for the variability in resorption efficiencies. Our results suggest that high K and P resorption from senescent leaves is an adaptive strategy allowing species to cope with soil nutrient scarcity. Furthermore, the level of nutrient immobilization in foliar compounds (N > P > K) seem to significantly determine the resorption process. We conclude that nutrient resorption from senescent leaves is a key process for plants to conserve nutrients in tropical forests of French Guiana, especially for K and P, where soil availabilities are low and depend mainly on soil parent material and leaching process. To sum up, in this Thesis we have demostrated how the elemental composition of the plant-soil system reflects ecological interactions and processes, such as intra and inter specific plant interactions (Chapter 2), poorly explored physiological processes such as nutrient resorption (Chapter 4) and the importance of stoichiometry studies for describing changes at ecosystem level and predicting future scenarios (Chapter 3). These studies add new knowledge to the ecological stoichiometry field and highlights the importance of this approach in the ecological studies.

Culvert flooding jeopardizes their use as safe crossing locations for animals, especially in locations with significative precipitation. The installation of elevated dry ledges inside culverts has been studied as a solution, although it is still not certain how effective they are. In order to tackle this problem, we tried to understand the under-road crossing patterns of mammals in culverts with and without ledges. We got enough data for six species, which showed carnivores had distinct preferences regarding culvert design and that culvert use was also dependent on environmental features surrounding it. Structure openness, distance to the nearest passage, water inside the culvert and season were the variables that most influenced crossing probabilities. Responses to these variables varied among species, highlighting the need for different type of structures that can fulfil each species’ necessities; RESUMO: “Padrões espaciotemporais de uso de passagens hidráulicas por mamíferos mediterrânicos terrestres” A inundação das passagens hidráulicas põe em risco o seu uso como locais de atravessamento seguro para os animais, especialmente em locais onde a precipitação é significativa. A instalação de passadiços elevados tem sido usada como solução, no entanto ainda não é conhecida com rigor a sua eficiência. Para tentar resolver este problema, estudámos os padrões de atravessamento por mamíferos em passagens com e sem passadiços. Apesar de só terem sido reunidos dados suficientes para seis espécies, determinámos que estes carnívoros têm preferências distintas quanto à estrutura da passagem e que o ambiente circundante também é um factor relevante no seu uso. A abertura das passagens, a distância entre elas, a quantidade de água e a estação foram as variáveis que mais influenciaram o uso. As respostas variaram entre espécies, mostrando a urgência de estruturas polivalentes que colmatem as necessidades de cada uma.

In the early life-stages, both epiphytic and terrestrial orchid seeds obtain carbon and nitrogen from mycorrhizal fungi for germination and seedling development. Epiphytic orchids are exposed to comparatively high light levels from an early stage of development and often produce green seeds therefore their responses to light and requirements for mycorrhiza-supplied C is likely to be different from terrestrial orchids. The effect of exogenous C, light and fungal partner on germination and establishment were studied in vitro for three terrestrial orchid and one epiphyte orchid. I found that terrestrial orchids require their fungal partner for development and that light inhibits this process. In epiphytic species, light only inhibited germination and early development in the absence of the mycorrhizal symbiont. The findings in this study shows for the first time the potential ecological importance of mycorrhizal fungi in overcoming light inhibition of seed germination and growth in both terrestrial and epiphytic orchid. I also investigate the impact of light, C and N budgets of terrestrial and epiphytes (using 13C and 15N tracers) and the amount of C and N the plant obtains from fungus to the adult orchid plants. The biomass and transfer of C and N from fungus to plant was increased upon exposure to light but only after germination had been already begun. The most cost benefit of mycorrhizal symbioses was examined as other studies have ignored C flow from plant to fungus. All three species gave C back to the fungus but in different quantities. Encyclia phoenicea provided significantly more C to its mycorrhizal fungi; twice the amount of G. repens and 2.4 times greater than D. fuchsii by mass. This confirms the mutualistic nature of G. repens-mycorrhiza interactions and reveals that this same trophic strategy operates in two additional orchid species for the first time.

Abstract Hydrologic Alteration and Sedimentation in the Upper Henry’s Fork Watershed Amelie Jeanne Charnaux The Henry’s Fork of the Snake River is venerated by the global recreational community as one of the finest trout fishing streams on the planet. Furthermore, this remarkable waterway flows within the bounds of one of the most important ecological corridors in the equally world-renowned Greater Yellowstone Ecosystem. While the recreational and biological features of this corner of Idaho may capture the interest of the broader public, the waterway is equally significant to the livelihoods of local interests, such as the ranching and farming communities. With the stakes running high for all interest groups, a case study of the Henry’s Fork watershed provides a valuable baseline narrative for understanding decision-making related to water resources not only in Idaho, but also in other Western states. Environmental impacts of the Henry’s Lake Dam and management of the stream below the structure were evaluated by literature review and GIS mapping, with research emphasis placed on the ecological integrity and fisheries of the Upper Henry’s Fork Subbasin. The literature review focused on natural processes in stream ecosystems and anthropogenic impacts, with the goal of providing information for the development of management policies that minimize the negative impacts of current flow management and land use. Literature sources overwhelmingly agree that the alteration of natural hydrologic regimes is the most serious and continuing threat to the sustainability of river ecosystems. In recent decades, downstream recreational fishing declined on the upper Henry’s Fork due to increased sedimentation, inciting investigation as to the source. Three major anthropogenic factors targeting one section of the river, the Henry’s Lake Outlet, set the stage for excess sedimentation. First, the Henry’s Lake Dam was constructed in 1923, impacting the Outlet’s hydrology through changes in the timing, magnitude, and frequency of low and high flows. Second, an artificial stream channel was constructed in the 1920s to bypass the meandering Outlet in order to increase conveyance capacity of irrigation water from Henry’s Lake to downstream water users. Third, long-term livestock grazing along this section of river dramatically reduced riparian and upland vegetation, triggering the loss of stream-bank stability and increasing erosion and sedimentation. These management practices have resulted in significant loss of biodiversity in the stream ecosystem and an increased rate of erosion in the Outlet. The Henry’s Lake Outlet restoration project, led by the Henry’s Fork Foundation, provides the opportunity to predict potential effects of large-scale restoration in the Henry’s Fork watershed. The project seeks to reduce sediment delivery downstream from the Outlet by rerouting flow from the straightened channel into the historic channel. The project tests the hypothesis that, by restoring the meandering stream channel, and thereby adding a half-mile to the Outlet, bank erosion and channel instability will decrease, the interaction between stream and riparian habitats will improve, and overall ecosystem health will benefit. In spite of the proactive intentions of the project, it will not change the current management of stream flow. In order to restore the Henry’s Lake Outlet to a state of dynamic equilibrium in terms of erosion and sediment load, the flows from Henry’s Lake Dam must more closely reflect the natural hydrologic regime. However, the ability to implement full restoration of the Outlet is complicated by the conflict between the requirements for ecosystem health and economic and socio-political pressures, a story common to many water systems throughout the West. Ultimately, it is hoped that this research may be integrated into policy and conservation strategy to mitigate streambank erosion and sedimentation in the Henry’s Fork Subbasin.

The chemical composition of snow, terricolous lichens and top-soil along with abundance and diversity of lichen communities were assessed in the Pechora and Usa basins, North-Eastern European Russia. Transects were established through the principal industrial towns of Vorkuta, Inta and Usinsk to assess the spatial extent of acid or alkaline and metal deposition. A further eight sites were selected to assess local impacts of oil and gas operations. In the Usa basin decreases of nitrogen concentration in the lichen Cladonia stellaris and winter deposition of non-sea salt sulphate moving northward were attributed to long range transport of oxides of nitrogen and sulphur from lower latitudes. Increased ionic content and pH of snow, along with elevated nitrogen concentrations and modified cation ratios in lichens (Cladonia arbuscula and Flavocetraria cucullata) within 25-40 km of Vorkuta and Inta were attributed to local deposition of alkaline coal ash. Nitrate concentration in snow did not vary with proximity to perceived pollution sources. Trace metal composition of winter snowpack, snow-melt filter residues and top-soils indicated elevated concentrations of elements associated with alkaline combustion ash around coal mining operations in Vorkuta and Inta, adding significantly to the soil metal loading as a result of ash fallout. Around the petrochemical industry near Usinsk there was little evidence of trace metal deposition. Acid deposition was associated with pristine areas, whereas alkaline combustion ash near to emission sources more than compensated for the acidity due to S02 and NOx. There were limited perturbations in the chemical signals in lichens, top-soils and lichen diversity close to an oil and gas industrial complex on the Kolva river. Here, there were elevations of lead and nitrogen concentrations in lichen apices and in the apical : basal nitrogen ratio in Flavocetraria cucullata, with lower lichen diversity of epigeal and epiphytic lichens. Elevated concentrations of Ba and Ca were found in soil-ash, probably as a result of local emissions from construction activity and gas flaring, rather than from long-range transport. Virtually all other sites remained unmodified and reflected background concentrations.The ecological impacts of the measured pollution loads are discussed.

This thesis examines the accumulation of persistent organochlorine compounds in Canadian mountain environments through the sampling of air and coniferous vegetation along a 1430-meter elevation gradient in the Canadian Rocky Mountains. Results showed that lower temperatures encountered in high altitudes favor the accumulation of chemicals with higher volatility in vegetation. Air concentrations further suggest that the reason for this accumulation in elevated areas is increased atmospheric deposition from distant sources and not from temperature-induced revolatilization from local terrestrial surfaces. Seasonal decreases in plant concentrations indicate evaporative processes, and volatilization from vegetation was confirmed by calculated fugacity gradients. However, volatilization contributes very little to air concentrations and the subsequent fractionation upslope, which appears to be dominated by long-range transport. Multivariate analysis revealed that, in addition to cooler temperatures, other environmental conditions common to mountain ecosystems, such as elevated precipitation and lower pressure, promote chemical deposition onto vegetation.

När storskaliga och kväveintensiva jordbruk bredde ut sig växte många betesmarker ochängar igen. Detta medförde att hävdberoende växtarter minskade eller helt försvann. Föratt kunna växa och återkolonisera marker behöver många arter olika störningar. En sådanstörning kan vara bränning. Vid bränning ökar ljusinsläppet och även kvävemängden imarken minskar, vilket gynnar de hävdberoende växterna.Detta arbete har undersökt om bränning kan vara ett komplement eller alternativ till beteoch slåtter vid bevarande av den biologiska mångfalden hos växter. I studien inventeradesbrända och orörda kontrollytor på 11 st olika gräsmarker i Östergötland. Dessagräsmarker inkluderar vägrenar, ängar, åkerslänter och naturbetesmarker.Tre olika diversitetsindex användes för att svara på om diversiteten var högre på brändamarkerna. Resultatet visade att diversiteten var högre och artfördelningen var jämnare påde brända ytorna än på kontrollytorna. De arter som är beroende av hävd hade en markantstörre utbredning på de brända markerna än på kontrollytorna. Detta bekräftar hypotesenom att bränning är positivt för hävdberoende växter och att bränning kan vara ettkomplement eller alternativ till bete och slåtter vid bevarande av den biologiskamångfalden av växter i gräsmarker. Den framtida skötseln skulle kunna vara olikakombinationer av bränningar, bete och slåtter.För naturvården kan detta konstaterande få betydelse genom att offentliga och privatamarkägare kan börja bränna fler områden med vetskapen att detta gynnar hävdberoendearter som är hotade. Att bränna marker istället för att slåttra eller beta kan leda till attstörre arealer kan få den skötsel de kräver utan förändringar i den finansiella budgetenhos markägaren.

When the large-scale and nitrogen-intensive agriculture gained land many naturalpastures and meadows started to overgrow. This led to that many species dependent onopen land decreased or totally disappeared. To grow or re-colonize land many speciesneed some form of disturbance. Burning can be one of such disturbances. Burningincrease the light inlet and decrease the amount of nitrogen in the soil. Both of thesechanges will favor the open-land species.The aim of this study was to explore if burning could be a complement or alternative tograzing and mowing for preserving the biological diversity among plants in grasslands.The different kinds of grasslands that were inventoried include hard shoulders, meadows,field slopes and natural pastures. Both burned and control areas were inventoried at 11places. All of them were located in different habitats in Östergötland, Sweden.Three different diversity-indexes have been used to answer the question if diversity washigher on the burned areas than on the control surface. The result showed that both thediversity was higher and the distribution in species spread more evenly on the burnedareas. Species dependent on open land had a notably larger spreading on the burned areasthan on the control areas. This confirms the hypothesis that burning has a positive effecton open-land species and can be a complement or replacement for grazing or mowing inpreserving the biological diversity of plants in grasslands. The future care could bedifferent combinations of burning, grazing and mowing.To the conservation, this knowledge can have a great impact for both state and privatelandowners. Knowing that this method will favor the open-land species, more areas canbe burned. To burn, instead of mowing or grazing, can lead to that larger areas can havethe proper maintenance it requires, without changes in the financial budget of thelandowner.

Genom sin aktivitet med dammbygge och trädfällning skapar bävern produktiva våtmarker med hög diversitet. Man har funnit att vid bäverns dammkonstruktion var artantalet närmare dubbelt så stort jämfört med i dammen och i det rinnande vattnet i bäcken. Ibland väljer bävern att inte dämma upp vattendragen, utan bygger en hydda längs med strandkanten, något som också kan gynna många arter (Törnblom & Henrikson 2011). Syftet med detta arbete är att undersöka hur själva bäverhyddan, byggd intill strandkanten, påverkar förekomsten av vattenlevande evertebrater. Provtagning på vattenlevande evertebrater har gjorts intill bäverhyddor byggda intill strandkanten, samt uppströms och nedströms varje bäverhydda. Statistiska uträkningar har sedan gjort på insamlad data för att se om det råder någon skillnad i antal individer, antal organismgrupper och diversitetsindex mellan bäverhyddan, uppströms och nedströms. Resultatet visar att det fanns en skillnad i antalet individer mellan hyddan, uppströms och nedströms. Det rådde ingen skillnad i antalet olika organismgrupper eller i diversitetsindex. Vattentemperaturens roll och skyddet som ansamlingen av grenar bidrar med är två aspekter som diskuteras som bidragande faktorer till det förhöjda individantalet vid bäverhyddan. Skillnaden i artsammansättning och artantal mellan bäverdammar och bäverhyddor byggda intill strandkanten är något annat som också diskuteras.
The activity of beavers creates productive wetlands with high biodiversity. A previous study found that dam constructions of beavers contribute to a higher number of aquatic invertebrate species compared to upstream and downstream sites. In some cases beavers build their hut along the shore without damming up the water flow (Törnblom & Henrikson 2011). This report is intended to determine how the beaver hut affects the abundance of water living invertebrates.Sampling at the beaver hut, upstream and downstream, of water living invertebrates was performed. To determine differences in individual number, species number and diversity index between the sites statistical calculation was performed. The results show a difference in individual numbers between beaver huts and downstream and upstream sites and the individual number was higher at the beaver hut than the two other sites. No difference in number of species or diversity index was found. The higher temperature of the water and more nutrition is two aspects that are discussed as contributing factor to the higher number of individuals near the hut. The difference in species and species number between a beaver dam and a beaver hut build long side the shore is also discussed.

Northern fringe populations generally have low amounts of genetic variation and inhabit habitats where specific adaptations are needed. On the Swedish west coast, the natterjack toad (Bufo calamita) inhabits skerry islands. I have examined: I) adaptation to two environmental stressors in this habitat; II) the genetic population structure within the skerry habitat; III) the effects of neutral genetic variation, selection and genetic drift on trait divergence within the skerry habitat; and IV) the effects of genetic variation on fitness under three thermal conditions of varying stressfulness. V) I have also studied the impact of putative local adaptations on the Scandinavian green toad (Bufo viridis) conservation programme. The results suggest that the skerry natterjack toads are locally adapted to the desiccation risk in their habitat. However, despite inhabiting a more saline habitat, they had a lower salinity tolerance when compared to their conspecifics in the more general habitat. The lowered salinity tolerance is most likely explained by the presence of negative genetic correlations between salinity tolerance and desiccation avoidance and suggests that the occurrence of multiple environmental stressors may constrain adaptation. Within the skerry habitat, the toads exhibited a strong population structure with populations differing in their levels of genetic variation. Moreover, within the skerry habitat, the results suggest uniform selection pressures. However, correlations between trait values and neutral genetic variation suggest that inbreeding depression may affect trait values and thus potentially constrain adaptation. In the natterjack toad, fitness costs associated with lack of genetic variation were only present under benign conditions and not under more natural conditions. This suggests that environmental stress masks inbreeding depression in these traits under natural conditions. In the study regarding the Scandinavian green toads, I found that one population inhabiting a saline habitat had a higher salinity tolerance than other populations in less saline habitats. This suggests the presence of local adaptation, which should be acknowledged in the green toad conservation programme. Several of the northern fringe populations of toads fulfill the criteria of being Evolutionary Significant Units and their conservation thus should be prioritized.

Cross-boundary movements of energy and material are ubiquitous. Freshwater ecosystems receive nutrients, dissolved, and particulate organic matter from adjacent terrestrial ecosystems, whereas terrestrial ecosystems mainly receive prey organisms and detritus deposited by physical processes such as floods from freshwater ecosystems. Within lakes, fish are considered as integrators between habitats due to their high mobility, although they often occupy either near-shore littoral or open-water pelagic habitats and develop habitat-specific morphologies. Such intra-population divergence in morphological traits might limit the use of multiple habitats. In this thesis, I first focused on quantity and quality of reciprocal fluxes of particulate organic matter between freshwater and terrestrial ecosystems and responses of recipient consumers. Freshwater ecosystems generally received higher amounts of externally-produced resources than terrestrial ecosystems. Despite this discrepancy, aquatic and terrestrial consumer responses were similar, likely due to the differences in resource quality. Second, I investigated the potential of particulate organic carbon (POC) supporting benthic food webs in lakes; a pathway that has largely been neglected in previous studies. I found that POC can substantially subsidize the benthic food web and that the effects on the benthic food web were transferred to the pelagic habitat, thus emphasizing the importance of benthic pathways for pelagic production. Third, I examined how water transparency can affect intra-population divergence in perch (Perca fluviatilis). I observed that increased water transparency can considerably increase morphological divergence between littoral and pelagic populations likely due to its effects on foraging. Finally, I investigated the effects of such intra-population divergence on littoral-pelagic food web coupling. I found that low morphological divergence corresponded with high overlap in resource use, whereas strong morphological divergence resulted in low overlap in resource use. Here littoral populations mainly utilized littoral resources and pelagic populations primarily utilized pelagic resources, indicating that habitat coupling might be strongly limited when intra-population divergence is high. In conclusion, although different ecosystems seem separated by distinct physical boundaries, these boundaries are often crossed. However, the development of habitat-specific adaptive traits might limit movement between apparently contiguous habitats.

Mammals in freshwater aquatic systems play important roles as ecosystem engineers, trophic transfer agents, and apex predators, thus acting as indicators of freshwater ecosystem function. Watersheds inhabited by semi-aquatic mammals have increased links between adjacent terrestrial and aquatic ecosystems compared to watersheds where they are not present. Semi-aquatic mammals not only exert top-down influences on streams, but are affected by bottom-up forces from the riparian system itself. The goal of this study was to identify variables that correlate with the presence of beaver (Castor canadensis), muskrat (Ondatra zibethicus), mink (Neovison vison), and river otter (Lontra canadensis), including their interactions, resulting in a better understanding of the areas where these semi-aquatic mammals occur and their effects on the riparian system. The objectives of this study were (1) to identify variables related to the probability of detection, initial occupancy, colonization, and extinction of the 4 semi-aquatic mammals in southern Illinois; and (2) to test if the reintroduction of river otter has changed stream food webs. To address my first objective, I sampled 120 bridge sites in 2 periods (winter: Jan-Feb; and spring: Mar-Apr) during 2012–2014 in 11 major watersheds in the southern third of Illinois (44,526 km2) to estimate multi-season occupancy. Each survey unit was a 400-m stream segment visited twice by 2 observers for a total of 4 observations per site per period. Observers recorded all mammal signs found, including sign species and type. Sites were Intensive Basin Survey Sites sampled by Illinois Department of Natural Resources (IDNR) and Illinois Environmental Protection Agency (IEPA), allowing data collected by the state to be available for explanatory variables for mammal occupancy. Data collected by the Illinois Natural History Survey (INHS) also were available for a subset of sites. I collected local- and landscape-scale habitat and weather variables for each site. I developed hypotheses regarding occupancy of sites based on land-cover, human disturbance, and stream attributes for each species. I developed additional hypotheses regarding prey availability and water quality for river otter and mink. Sites used in each analysis were dependent on data available to address the hypotheses of interest. Beaver and muskrat were present at ≥100 of 103 sites for ≥1 observation. Naïve occupancy was high (≥82%) every year for both species. Detection probabilities for beaver and muskrat were best predicted by survey period. Beaver detection remained fairly constant across survey periods except for a decrease in winter 2014, whereas muskrat detection was generally lower during winter and higher during spring. Beaver were more likely to occupy larger streams than smaller streams during the initial survey period. Sites that lacked a dominant land-cover had a lower probability of beaver colonization than sites dominated by agriculture or woody vegetation at the landscape scale. In addition, the probability that a site would be colonized by beaver during the study increased with availability of water within 1 km of the surveyed segment, increased stream density, sites at larger streams, and river otter presence during the previous period. The probability of site extinction decreased as stream size, stream density within 1 km, and water availability within 500 m of the survey segment increased. Occupancy of muskrat during the initial survey period was negatively predicted by % forest in the 1-km riparian area, channel incision, and amount mercury in the sediment. Colonization by muskrats was lower during the long spring to winter intervals than the short winter to spring intervals, and was positively related to the amount of organic carbon in the sediment. The probability of site extinction by muskrat increased with increasing % forest within the riparian area around the stream segment, decreasing 1-km stream density, and when land-cover within 1 km of sites was dominated by agriculture or woody vegetation. Multi-season occupancy of river otter and mink were assessed in 2 separate analyses that used either land-cover and management variables or prey availability and riparian community composition, respectively. In the first analysis, river otter and mink were present at ≥84 of 103 sites. Naïve occupancy was higher every year for mink (≥88.3%) than for river otter (≥55.3%). Detection of river otter and mink in the first analysis increased as substrate availability increased. Occupancy of river otter during the initial survey period was predicted by large stream size, low % developed area within 250 m of the surveyed segment, and proximity to nearest river otter reintroduction point. Probability of colonization by river otter varied by survey period and was higher at sites with larger streams, higher stream density, lower % developed area, and within a known river otter population area. Site extinction by river otter in the first analysis varied by survey period and was linked to increased organic carbon in the sediment, and decreased road density within 1 km of the surveyed segment. River otter harvest was not found to affect site colonization or extinction. Mink occupancy during the initial period was negatively associated with water availability within 100 m of the survey segment. Site colonization by mink varied by month and increased with increasing developed area within 100 m of the surveyed segment, increasing channel incision, and decreasing rainfall. Probability of site extinction for mink increased as stream size and developed area within 500 m of the surveyed segment increased, and when woody vegetation was the dominant land-cover type within 1 km of the surveyed segment. The second analysis of multi-season occupancy of river otter and mink used 77 sites, 81.8% of which had ≥1 river otter detection in the study and 98.7% of which had ≥1 mink detection. Naïve occupancy differed between years but gradually increased for river otter and remained high (≥93.5%) for mink. Increasing substrate availability increased the probability of river otter detection, whereas mink detection varied by survey period. Occupancy during the initial survey period was higher in sites closer to the reintroduction points for river otter. Probability of colonization of river otter was positively associated with macroinvertebrate IBI and fish species richness, sites with high fish species richness of fish families preferred by river otter also had reduced otter extinction probability. No tested variables predicted initial occupancy for mink, but mink were more likely to colonize sites with increased fish richness and when muskrat were present during the previous period. Mink had decreased probability of extinction in sites with increasing mussel community index. My results indicate that semi-aquatic mammals in Illinois were affected by a riparian habitat, water availability, and stream community variables at both the landscape and local scale. I found high occupancy of mink, beaver, and muskrat across the entire landscape of southern Illinois, and my results suggest that the geographic range of river otter continues to expand. Relationships of occupancy of these semi-aquatic mammals to measurements of urban areas and human disturbance were not consistent across all species. Mink and river otter occupancy were both predicted by aspects of prey availability, indicating the importance of predator-prey relationships in occupancy dynamics of riparian predators. Hypotheses regarding predator pressure and changes in environmental variables were used to test the effects of river otter reintroduction on stream communities. For this objective, I used structural equation models. I compared fish and macroinvertebrate communities from before (1982-1995) and after (2005-2013) reintroduction of river otter, which occurred in 1994–1996. Fish and macroinvertebrate community data for 35 sites located throughout 6 major watersheds in southern Illinois (25,550 km2) were obtained from state agencies. Changes in stream communities were evaluated using 4 metrics (species richness, species dominance, skewness in size distribution of prey, and proportion of individuals in the size class preferred by river otter). Neither the inclusion of river otter site use nor change in stream quality, measured by change in % forest, improved models over the simple model which only included fish and macroinvertebrate communities. Overall, I found no evidence that river otter presence or change in forest cover affected stream fish and macroinvertebrate communities.

Prey species defend themselves behaviorally and morphologically, and often utilize varied antipredator strategies against dissimilar predator types (i.e. terrestrial vs. aerial). Striped skunks (Mephitis mephitis) spray noxious secretions at predators and advertise this danger with deterrent behaviors and black-and-white aposematic coloration. Evidence suggests skunks are effective at deterring terrestrial mammalian predators but are vulnerable to aerial predators; how skunks assess the risk posed by different predator types, however, has not been examined empirically. I recorded the behavioral responses of skunks to audio playbacks of coyotes and great horned owls (the primary terrestrial and aerial predators of skunks, respectively), and peregrine falcons and white noise as controls, as well as to a visual remote controlled model. Skunks engaged in vigilance and running away more often in response to owl vocalizations, suggesting skunks perceive owls as more threatening relative to coyotes. Skunks were more likely to foot stomp and run away in response to the remote controlled model compared with coyote vocalizations, implying visual cues were perceived as more risky than audio cues. This study elucidates how a well-defended mammal can determine which perceived threat is most risky and alter its behavior when its main defense strategy is not successful against all predator types.

An organism that is transferred from one place to another, causing major problems to the native species is termed invasive. Its natural dispersal across barriers may have been prevented but as man has turned able to rapidly travel all over the world organisms are brought to sites where they were never before observed. Adding the increasing global warming organisms may find it necessary to move around even further. This might cause major disturbance to the biological diversity, and hybridization and homogenization is one of many scenarios that could disturb the native diversity. In Sweden more that 2/3 of all alien plant species have been introduced to disturbed areas and the major introduction mechanism is gardening. The object of study in this presentation, Pimpinella major (Apiaceae) was introduced in Sweden alongside garden grasses during the 19th century but has so far spread only marginally from the areas of introduction. The aim of the study was to quantify the appearance of Pimpinella major in different types of vegetation apart from road verges, where it has been noted systematically for over a decade. The investigation area covers most of the Tullgarn nature reserve. The result shows an astonishing tendency of P. major to remain growing only along the roads in the area. The very few findings besides next to roads are from deciduous and coniferous forests and fields. It seems that Pimpinella major almost without exception prefers heavily disturbed areas and access to large amounts of nitrogen fertilizer from exhaust fumes

Modern methods for managing pine (Pinus sylvestris) create homogenized forests. This decreases nature’s potential for biodiversity and might threaten species in need of different types of milieu. The main purpose of this study was to investigate how important older pine trees are for biodiversity. In the Hall-Hangvar Reserve in the north-west part of Gotland, insects collected from traps showed that more species were found in old or dead trees compared to younger pine trees. A statistically significant difference was found for Coleoptera (beetles). The taxons of greatest interest for this study were Coleoptera and Hymenoptera (wasps). Certain families of Hymenoptera use ducts made by larvae from some families of Coleoptera.These larvae also serve as prey. Relevance concerning enviromental importance to species and diffrenences in inhabiting the three stages of pine trees was of importance.

Common species of freshwater mussels may, like the freshwater pearl mussel (Margaritifera margaritifera) have a drastic decline in number and there is several reasons, like sedimentation, a decline of host fishes, introduction of alien species, nutrition leakages from agriculture and pollutants of medic drugs and poison. Ann Gustavsson made in the year of 2007 a study over rejuventation of freshwater great mussels in nine watersystems and considered that the rejuventation within the populations were all along the line poor. This study orients from her work and points to determine if there is a connection between the poor juventation and pollution of nitrogen and phosphorous from industries and private sanitations. The study was performed with the software program ArcGIS9.2 to take out drainage areas for the concerned habitats and contact was made with the concerned authoritys. When it comes to supervision of private sanitations is it the countys and for industries is it the county administrative board. Most of the countys had a very difficult way to reach their data of the private sanitations and those who had data had great holes in their knowledge in them. The greatest emission of nitrogen was without doubt the industries, but a more even allocation could be seen in the pollution of phosphourus, where the industries and the private sanitations stood for about fifty- fifty of the pollution. The greatest emission of nitrogen and phosphourus happened in Viskan, in the drainage area for Lekvad,there it was a lack of mussels. The species of Anodonta anatina showed a strong positive correlation between emission of nitrogen and phosphourus with the way of juvenile mussels in the population. More studies is need to do in these areas, both when it comes to continuing mapping of rejuventation within the freshwater great mussels in several waters and template value for pollution of nitrogen and phosphourus, that is very doubtful today. Even studies concerning other factors, like predation, host fishes and the influence of poison and medic drugs is needing to do, as it is few studies concerning this today.

The transfer of threatened animals from one location to another in order to benefit the species is a technique frequently used by animal conservation managers. However, very few of these relocations have experimentally assessed the relative merits and disadvantages of commonly used release techniques. Two species of hare-wallaby, mala (Lagorchestes hirsutus) and merrnine (Lagostrophus fasciatus), were reintroduced in August 2001 onto Peron Peninsula in Western Australia. These threatened species were reintroduced using two release strategies (soft versus hard release), and their subsequent movements and body condition were monitored using radio-telemetry and trapping.

For the most part, there is no doubt that human impact on biodiversity has been negative: habitat loss and degradation, pollution, overexploitation, and introduction of invasive species had played significant roles in biodiversity decline. However, human impact on Earth is not always so detrimental and its effects are not the same for all taxa. The aim of this thesis was to assess the anthropogenic impact on one of the most endangered and often unnoticed groups - terrestrial molluscs - firstly focusing on natural and then urban context. In Chapter I, effects of forest age as a surrogate for forest continuity on land snail richness and composition in Tuscan evergreen and deciduous woods were assessed. Chapter II explored the role of dispersal and local environment in urban land snail assemblages comparing different human-made habitat types in three cities in central Italy (Grosseto, Siena and Arezzo). Finally the link between man and urban environment has been further elaborated in Chapter III, where a fully synanthropic land snail species (Papillifera papillaris) has been used to assess athmosferic pollution from human activities, especially vehicular traffic, in the urban area of Siena. Concerning results obtained, Chapter I revealed that successional age as surrogate for forest continuity parameter seemed not to be a key factor in controlling land snail species richness and abundances but habitat structure more than forest age was the factor mostly involved in affecting communities; furthermore, no difference was found between evergreen and deciduous oak litter in terms of land snail richness, abundance and diversity. Focusing on urban environment, Chapter II demonstrated that cities can show relatively high land snail richness with values comparable to natural areas. After having accounted and later removed spatial structures influence, urban gradient effect turned out to be the principal component structuring urban land snail assemblages. This finding proved a likely human-mediated transport, which enhances dispersal abilities of organisms normally considered scarcely mobile. However, no establishment there would be in the absence of suitable microhabitat conditions. In particular, “vegetation cover” and “distance from the city centre” were the environmental variables that explained most of the variation in species composition. In Chapter III, results elected Papillifera papillaris a promising species to monitor the metal distribution and bioavailability in urban environments and to evaluate the possible transfer of pollutants to higher levels in food chains. Mollusc soft tissues showed very low concentrations of lithophile elements, and much higher concentrations of anthropogenic metals such as Cd, Cu, Pb, and Zn while excreta and traditional biomonitors such as mosses were the matrices most involved in lithophile contamination. Surprisingly, Papillifera papillaris tissues showed extreme Mn values. These concentations, for their magnitude, have no comparison with those reported in literature for other species of terrestrial gastropods. Excreta showed a high concentration of Pb, demonstrating the scarce bioavailability and absorption of this element and probably its limited impact on urban food chains.

Most studies of wetlands tend to focus on the biotic and abiotic interactions within the aquatic habitat. Though wetlands and associated biota may appear to be somewhat isolated from the influence of the wider landscape, wetland habitats are critically linked with adjacent terrestrial habitats and other wetlands through the two-way flows of energy and nutrients and provision of structure. While an understanding of these inter-habitat linkages is breaking down the perceived boundaries between "aquatic" and "terrestrial" ecosystems, there is more limited knowledge on the ecology of wetland animals that must meet critical needs in both aquatic and terrestrial habitats at some time during their life or seasonal cycles. Here, I examine the terrestrial ecology of a freshwater turtle, the eastern long-necked turtle (Chelodina longicollis) in the temporally dynamic and heterogeneous landscape of Booderee national park in south-east Australia by 1) providing a description of terrestrial behaviours, 2) identifying the factors driving terrestrial behaviour and its functional significance, 3) examining factors that may limit or constrain terrestrial behaviour and 4) demonstrating how various terrestrial behaviours can factor prominently in the overall biology of a nominally aquatic animal. Chelodina longicollis used terrestrial habitats for reasons other than nesting, including aestivation and movements between wetlands. Radio-telemetry of 60 turtles revealed that nearly 25 % of all locations were in terrestrial habitats up to 505 m from the wetland, where turtles remained for extended periods (up to 480 consecutive days) buried under sand and leaf litter in the forest. Individuals also maintained an association with a permanent lake and at least one temporary wetland within 1470 m, though some inter-wetland dispersal movements were much longer (5248 m). As a result of their associations with several wetlands and terrestrial aestivation sites, C. longicollis traversed large areas and long distances (13.8 +/- 2.8 ha home range, 2608 +/- 305 m moved), indicating that this species is highly vagile. In fact, a three-year capture-mark-recapture study conducted in 25 wetlands revealed that 33% of the population moved overland between wetlands. After scaling this rate to the number of generations elapsed during the study, C. longicollis moved between discrete water bodies at a rate of 88-132% per generation. This rate is not only high for freshwater turtles, but is among the highest rates of inter-patch movement for any vertebrate or invertebrate. Chelodina longicollis demonstrated an impressive capacity for individual variation in nearly every aspect of its behaviour examined. Most of the variation in space use, movements, terrestrial aestivation and activity could be attributed to extrinsic local and landscape factors, seasonal influences and rainfall, whereas intrinsic attributes of the individual such as sex, body size, body condition and maturity status were less important. Turtles increased movement distance and home range size in regions where inter-wetland distances were farther and with increasing wetland size. Individuals spent more time in terrestrial habitats with decreasing wetland hydroperiod and increasing distance to the nearest permanent lake. Overland movements between wetlands were correlated with rainfall, but the directionality of these movements and the frequency with which they occurred varied according to the prevalent rainfall patterns; movements were to permanent lakes during drought, but turtles returned to temporary wetlands en masse upon the return of heavy rainfall. However, deteriorating conditions in drying wetlands forced turtles to move even in the absence of rainfall. Captures at a terrestrial drift fence revealed that immature turtles as small as 72.3 mm plastron length may move overland between wetlands with similar frequency as larger adults. Taken together, these results suggest that C. longicollis behaviour is in part conditional or state-dependent (i.e., plastic) and shaped by the spatiotemporal variation and heterogeneity of the landscape. Perhaps the most surprising aspect of individual variation was the alternate responses to wetland drying. Turtles either aestivated in terrestrial habitats (for variable lengths of time), or moved to other wetlands. Movement to other wetlands was the near universal strategy when only a short distance from permanent lakes, but the proportion of individuals that aestivated terrestrially increased with distance to the nearest permanent lake. When long distances must be travelled, both behaviours were employed by turtles in the same wetland, suggesting that individuals differentially weigh the costs and benefits of residing terrestrially versus those of long-distance movement. I propose that diversity in response to wetland drying in the population is maintained by stochastic fluctuations in resource quality. The quality of temporary wetlands relative to permanent wetlands at our study site varies considerably and unpredictably with annual rainfall and with it the cost-benefit ratio of each strategy or tactic. Residency in or near temporary wetlands is more successful during wet periods due to production benefits (high growth, reproduction and increased body condition), but movement to permanent wetlands is more successful, or least costly, during dry periods due to the fitness benefits of increased survival and body condition. I used the doubly-labelled water (DLW) method to provide the first estimates of water and energy costs of aestivation and overland movement for any freshwater turtle behaving naturally in the field. Chelodina longicollis remained hydrated while terrestrial with water flux rates (14.3-19.3 ml kg-1 d-1) on par with those of strictly terrestrial turtles, but field metabolic rate during aestivation (20.0-24.6 kJ kg-1 d-1) did not indicate substantial physiological specializations in metabolism during aestivation. Energy reserves, but not water, are predicted to limit survival in aestivation to an estimated 49-261 days, which is in close agreement with the durations of natural aestivation. The energy costs of overland movement were 46-99 kJ (kg d)-1, or 1.6-1.7 times more expensive than aestivation. When a wetland dries, a turtle that foregoes movement to other wetlands can free sufficient energy to fuel up to 134 days in aestivation. The increasing value of this energy "trade-off" with travel distance fits our behavioural observations of variance in response to wetland drying. Taken together, this evidence indicates that terrestrial habitats provide more than just organic and structural inputs and filtering services and that nearby wetlands are important for reasons other than potential sources of occasional colonists to a population. Terrestrial habitats are used for aestivation in response to wetland drying and different wetlands are diverse in their functions of meeting the annual or life-cycle requirements of C. longicollis in temporally dynamic wetland systems. As overland movements between these various habitat types are in response to spatiotemporal variation in habitat quality and associated shifts in the fitness gradient between them, I suggest that terrestrial and different aquatic habitats in Booderee offer complementary resources contributing to regional carrying capacity and population persistence of the turtle population. Thus, important ecological processes regulating C. longicollis in a focal wetland should not be viewed as operating independently of other nearby wetlands and their adjacent terrestrial habitats. Collectively, these findings highlight the complex and dynamic associations between a population of freshwater turtles and the wider terrestrial and aquatic landscape, demonstrating that turtle populations and the factors that impact them can extend well beyond the boundaries of a focal wetland.