The long-term changes in distribution and numbers of bird species in the Czech Republic were analysed using published data from Breeding Birds Atlases in the Czech Republic (1973-77, 1985-89 and 2001-03). Each species were categorized by taxonomical group, migratory strategies, biogeography type, breeding habitat, breeding population size in Europe and in the Czech Republic a body size. The changes in numbers and changes in distribution were inter-correlated Increase in distribution as well as in numbers were recorded in rare and large species, in species increasing in whole Europe and in bird species protected under Czech legislation. Interesting pattern in population was found in waterbirds, where piscivorous species are increasing, whereas other (mostly grebes, ducks etc.) species are decreasing.

The subject of this diploma thesis is the analysis of long-term changes in precipitation in Europe over the period 1961 - 2011. Emphasis is placed on determining differences in values of trends in precipitation among selected data sources and on analyzing the spatial distribution of annual and seasonal changes in precipitation in Europe, including a discussion of possible causes of differences in these changes in individual areas. Another aim is to illustrate, describe and account for the differences in trend values among different data sources: the ECA&D station database, the interpolation network data sets E-OBS and CRU TS and two reanalyses JRA-55 and NCEP/NCAR. Depending on the amount and quality of data available for the comparison of data sets, changes in precipitation totals were described over a long-term scale in absolute and also, to a lesser degree, in relative values. The first part summarizes the scientific literature dealing with the changes in precipitation characteristics throughout the world and in Europe. There follows a description of the suitability of individual types of data sources for estimating trends in precipitation totals. Scientific articles usually describe long-term changes based on a single data source rather than using a variety of individual types of data sources....

<p>In this thesis I examine and evaluate the effects of a documented large-scale eutrophication on macroalgal vegetation on the Swedish coast. During the past century the load of nutrients has increased manifold in the Baltic Sea area, increasing primary production and organic sedimentation significantly. By re-investigating a unique reference material of macroalgal vegetation from the 1940-60s and by conducting new diving studies at the same sites, I showed that long-term trends in macroalgal community composition and species’ distributions are consistent with changes expected from an increased nutrient availability. In the Öregrund archipelago (northern Baltic Sea), I documented a declined depth distribution of the dominant canopy forming alga, <i>Fucus vesiculosus</i>, and an increased abundance of opportunistic ephemeral algae compared to 52-53 years ago. In the Gullmar Fjord area (Skagerrak), trends included increased abundances of functional groups with opportunistic algae, decreased abundances of large perennial algae and a general decline in the depth distribution of the vegetation compared to 36-57 years ago. Sediment removal experiments in the northern Baltic Sea confirmed the hypothesis that sedimentation influences macroalgal community composition. Species depending on short periods of reproduction were clearly favoured by sediment removal, especially <i>F. vesiculosus</i> that seemed limited in depth by the local sediment load. Species with long continuous periods of dispersal by spores and/or fragments (for example the ephemerals <i>Cladophora glomerata</i>, <i>Ceramium tenuicorne</i> and <i>Enteromorpha</i> spp.) were more tolerant to the natural sediment load. In general, sediment removal favoured macroalgal establishment and development, indicating that variation in the natural sediment load is an important constraint for sublittoral rocky-shore macroalgal community development. I conclude by suggesting that the documented long-term changes in macroalgal vegetation on the Swedish coast partly are explained by an increased organic sedimentation in these areas.</p>

In this thesis I examine and evaluate the effects of a documented large-scale eutrophication on macroalgal vegetation on the Swedish coast. During the past century the load of nutrients has increased manifold in the Baltic Sea area, increasing primary production and organic sedimentation significantly. By re-investigating a unique reference material of macroalgal vegetation from the 1940-60s and by conducting new diving studies at the same sites, I showed that long-term trends in macroalgal community composition and species’ distributions are consistent with changes expected from an increased nutrient availability. In the Öregrund archipelago (northern Baltic Sea), I documented a declined depth distribution of the dominant canopy forming alga, Fucus vesiculosus, and an increased abundance of opportunistic ephemeral algae compared to 52-53 years ago. In the Gullmar Fjord area (Skagerrak), trends included increased abundances of functional groups with opportunistic algae, decreased abundances of large perennial algae and a general decline in the depth distribution of the vegetation compared to 36-57 years ago. Sediment removal experiments in the northern Baltic Sea confirmed the hypothesis that sedimentation influences macroalgal community composition. Species depending on short periods of reproduction were clearly favoured by sediment removal, especially F. vesiculosus that seemed limited in depth by the local sediment load. Species with long continuous periods of dispersal by spores and/or fragments (for example the ephemerals Cladophora glomerata, Ceramium tenuicorne and Enteromorpha spp.) were more tolerant to the natural sediment load. In general, sediment removal favoured macroalgal establishment and development, indicating that variation in the natural sediment load is an important constraint for sublittoral rocky-shore macroalgal community development. I conclude by suggesting that the documented long-term changes in macroalgal vegetation on the Swedish coast partly are explained by an increased organic sedimentation in these areas.

Tese(doutorado) - Universidade Federal do Rio Grande, Programa de Pós–Graduação em Oceanografia Biológica, Instituto de Oceanografia, 2011. / Submitted by Cristiane Gomides (cristiane_gomides@hotmail.com) on 2013-12-15T11:04:17Z No. of bitstreams: 1 leonrdo.pdf: 9078429 bytes, checksum: af7d36e3035868040d998b9669ce02ee (MD5) / Approved for entry into archive by Sabrina Andrade (sabrinabeatriz@ibest.com.br) on 2013-12-18T17:39:33Z (GMT) No. of bitstreams: 1 leonrdo.pdf: 9078429 bytes, checksum: af7d36e3035868040d998b9669ce02ee (MD5) / Made available in DSpace on 2013-12-18T17:39:33Z (GMT). No. of bitstreams: 1 leonrdo.pdf: 9078429 bytes, checksum: af7d36e3035868040d998b9669ce02ee (MD5) Previous issue date: 2011 / Utilizando dois bancos de dados mensais (1979-1984; 1996-2011) constituídos por um regime de amostragens experimentais independentes da pesca, o objetivo deste estudo foi avaliar a hipótese central de que mudanças de longo prazo na abundância e diversidade de peixes nas zonas rasas do estuário da Lagoa dos Patos (ZRELP) ocorreram nas últimas 3 décadas, as quais foram promovidas por distúrbios nos habitats estuarinos e alterações no esforço de pesca na região. Os padrões de composição e abundância das espécies de peixe que utilizam as ZRELP apresentam alta variabilidade anual e inter-anual, as quais são reguladas principalmente pelas variações ou flutuações da temperatura, salinidade, vazão estuarina e componente meridional do vento. Os resultados deste estudo revelam que o Modo Anular Sul (SAM) também parece influenciar a dinâmica temporal dos peixes nas ZRELP, além do El Niño Oscilação Sul (ENOS), e que o tempo de resposta das espécies em relação a alguns fatores abióticos (e.g., temperatura e vazão) não é instantâneo. Por fim, o presente estudo revela que mudanças de longo prazo ocorreram na abundância e diversidade das espécies nos últimos 30 anos. Estas mudanças estiveram provavelmente associadas às alterações nas condições hidrológicas do estuário promovidas pelos fenômenos ENOS e SAM. A perda de habitat, especialmente dos vegetados, e a pressão de pesca representada pelo esforço de pesca também parecem ter importante papel sobre as mudanças de longo prazo observadas, principalmente para espécies como a Brevoortia pectinata, Jenynsia multidentata, Micropogonias furnieri e Mugil liza. A partir do conjunto de informações reunidas, o presente estudo reforça a hipótese que os padrões de uso do estuário da Lagoa dos Patos, especialmente pelos juvenis, estão fortemente vulneráveis às mudanças no clima e às transformações antrópicas do estuário, a despeito da alta variabilidade destes padrões forçada pelo dinamismo estuarino. / Using two long-term database (1979-1984; 1996-2011) composed by experimental fishery-independent sampling survey, the aim of this study was to evaluate the main hypothesis that long-term changes in fish abundance and diversity in shallow areas of the Patos Lagoon Estuary (SAPLE) occurred in the last three decades, which were promoted by estuarine habitats disturbances and alterations in fishing effort changes in the region. The composition and abundance patterns of fish species inhabiting SAPLE present high annual and inter-annual variability, which are mainly regulated by changes or fluctuations in temperature, salinity, freshwater outflow into the estuary and meridional wind component. The results show that the Southern Annular Mode (SAM) also seems to be influencing the temporal dynamics of fishes in SAPLE besides of the El Niño Southern Oscillation (ENSO), and that time response of species to changes in some environmental variables (e.g., temperature and freshwater outflow) is not in phase. Finally, this study shows that long-term changes occurred in the species abundance and diversity in the last 30 years. These changes were probably associated to changes in the estuarine hydrological conditions promoted by ENSO and SAM phenomena. The habitat loss, especially of the vegetated ones, and the fishing pressure represented by fishing effort also seem to have important role on observed long-term changes, especially to Brevoortia pectinata, Jenynsia multidentata, Micropogonias furnieri e Mugil liza. From the total information gathered, the present study reinforce the hypotheses that the fish use patterns in the Patos Lagoon estuary, especially by juveniles, are highly vulnerable to climate change and to man-induced estuarine transformations, despite the high variability of these patterns associated with the estuary dynamics.

Abstract Previous reports on the effects of enhanced UV-B radiation on bryophytes have been equivocal. This study shows that mosses not only respond to enhanced UV-B, but they are affected by changes in ambient radiation. The studies were conducted with two model species common in northern environments; red-stemmed feather moss (Pleurozium schreberi) and juniper haircap moss (Polytrichum juniperinum). Both species showed high concentrations of methanol-extractable UV-absorbing compounds (UACs) with high spring-time and early-summer UV, whereas in P. juniperinum, the concentration was affected by early-summer drought. The UACs of P. juniperinum increased again towards autumn suggesting a role in winter hardening. The (spring-time) cell wall-bound UV screen was important to both species. The fundamental adaptation of P. juniperinum to open and exposed environments was reflected in relatively higher concentrations of total UACs compared to P. schreberi. The enhanced UV-B experiments in situ were conducted over two years in Oulu and six years at the FUVIRC site in Sodankylä. Some of the effects of UV-B were seen within the first years of the experiments, or even within hours, while others were observed after several years. Five or six years of enhanced UV-B treatment increased the methanol-extractable UACs of P. schreberi and decreased the green shoot growth of P. juniperinum. The immediate light environment was proposed to have an impact on the varying UAC concentrations. Some mitigating effects of UV-A were observed as well. Off-site measured, reconstructed and modelled UV radiation data was used for comparisons of light environment in situ, or when performing a reconstructive research with historical samples. The environmental sample banks can provide a useful tool to study past environmental conditions, and even reconstruct past radiation levels. It was shown in this study that UACs in P. schreberi and P. juniperinum have fundamental roles as UV-B screens in the cell walls, but there is also a variable response with the soluble fraction that reacts and adapts to the changes in UV radiation. The responses to increasing UV-B radiation vary in magnitude and in time. As P. schreberi and P. juniperinum possess circumboreal and cosmopolitan distributions, the effects of UV-B on these species and consequently on ecosystems has a broad application.

Les estuaires font partie des écosystèmes les plus productifs de la planète. Ils constituent une zone d'importants échanges de matières et jouent à ce titre un rôle capital pour les cycles biogéochimiques. Du fait de leur position à l'interface entre domaines continental et marin, ils sont également un lieu de passage obligatoire pour de nombreuses espèces de poissons migrateurs ou encore de nourricerie et de refuge. Ces systèmes sont contraints par de nombreuses pressions de natures diverses dont certaines en lien avec les activités humaines locales (p. ex. pêcheries, transport maritime, dragages, pollutions accrues, etc.). Ces altérations viennent s'ajouter à la variabilité intrinsèque de ces systèmes naturellement complexes (variabilité spatio-temporelle de différents facteurs environnementaux ; c.-à-d. température, salinité, turbidité, etc.). Toutefois, une intensification de ces d'altérations, dont une partie est associée à la composante climatique des changements globaux, est observée depuis ces dernières décennies. Ces modifications avérées et leurs incidences sur les communautés biologiques constituent un enjeu en matière de gestion des écosystèmes estuariens. Cependant, par manque de chroniques de données continues suffisamment longues, peu d'études sur l’évolution à long terme de systèmes estuariens ont été réalisées à ce jour. Pour mes travaux, j'ai eu à ma disposition un ensemble de chroniques uniques - acquises depuis 35 ans - associées à plusieurs suivis écologiques de l'estuaire de la Gironde (notre site atelier). L'objectif général de cette thèse est de caractériser l’évolution globale du système dans son ensemble (physico-chimie et biologie) et d'identifier les forçages impliqués. L’originalité de ces travaux, par rapport aux études spécifiques déjà menées, consiste à analyser l’évolution de l’ensemble des descripteurs caractéristiques du fonctionnement d'un système modèle et de qualifier la part relative aux forçages globaux. L'étude des séries chronologiques, via une approche end-to-end basée sur des analyses multivariées, permet d'identifier deux changements abrupts d'état de l'écosystème de l'estuaire de la Gironde, associés à des fluctuations hydroclimatiques à large échelle (bassin Atlantique nord) mais aussi à une échelle plus locale (estuaire). Des hypothèses relatives aux possibles mécanismes impliqués, reliant les altérations climatiques à large échelle aux altérations observées à l'échelle des communautés biologiques estuariennes, sont discutées. Un deuxième volet de la thèse, au travers d’une approche modélisatrice basée sur le concept de niche d'Hutchinson, permet d'identifier un changement de répartition spatiale, longitudinale, des populations de copépodes estuariennes en réponse au réchauffement des masses d'eau et à la marinisation de l'estuaire. Enfin un troisième volet de mes travaux s'est consacré à l'étude spécifique d'une espèce de copépode invasive : Acartia tonsa. Suivant une double approche modélisatrice permettant d'estimer à la fois les niches fondamentale et réalisée de l'espèce, ces travaux illustrent l'importance relative des changements climatiques qui ont facilité la colonisation et l'essor de cette espèce dans l'estuaire. / Estuaries are among the most productive ecosystems on Earth. They constitute important areas for materials exchanges and play therefore a crucial part in biogeochemical cycles. Because of their location at the interface between marine and continental realms, they are also a migratory path for different fish species and in some cases, a nursery or a refuge area. These systems are submitted to many pressures, some of them being related to anthropogenic activities (e.g fisheries, maritime traffic, dredging, rising pollutions, etc.). These changes are superimposed to the intrinsic variability of these naturally complex ecosystems (characterized by a spatio-temporal variability of different environmental factors; i.e., temperature, salinity, turbidity, etc.). However, since recent years, an intensification of these alterations, being partly linked to the climatic component of Global Change, is observed. These changes, already documented, and their incidence on biological communities, constitute a challenge for the future management of estuarine ecosystems. However, due to a lack of long-term continuous time series, for now few studies on the long-term evolutions of estuarine systems have been reported. In this work, I used a unique set of data (35 years) provided by an ecological monitoring of the Gironde estuary (the model of estuary used in the study). The main objective of this thesis is to characterize the evolution of the whole system (physico-chemistry and biology) over the last three decades and to identify the forcings involved. The originality of this work comes from a global analysis of the main estuarine descriptors and from the evaluation of the relative contribution of global forcings. A study based on multivariate analyses, through an end-to-end approach, reveals two abrupt shifts in the state of the ecosystem of the Gironde estuary. These two changes appear to be linked to hydroclimatic fluctuations at a regional scale (North Atlantic basin) and also at a local scale. Some hypotheses on the possible mechanisms involved, linking the large-scale climatic alterations to the changes observed on the biological estuarine communities are discussed. A second study that uses a modeling approach based on the ecological niche concept of Hutchinson, identifies a change in the spatial (longitudinal) distribution of estuarine copepod populations in response to warming and marinisation processes. Finally, a third work focuses on an invasive copepod species: Acartia tonsa. A double modeling approach estimates both the fundamental and realized niches of the species. The results highlight the relative importance of climate changes that facilitated the colonization of the estuary by A. tonsa.

Les rivières en tresses constituent des plaines alluviales complexes constituées d'une mosaïque d'unités correspondant à des échelles spatio-temporelles différentes. L'objectif de cette thèse a été d'utiliser des données de LiDAR aéroporté pour améliorer la connaissance des réponses morphologiques des lits en tresses à différentes échelles spatio-temporelles. Dans un premier temps, 2 levés LiDAR séquentiels ont permis de détecter les changements morphologiques d’une tresse de 7 km survenus suite à une crue de période de retour 14 ans. Ces travaux ont été réalisés sur le site du Bès, un affluent de la Bléone. Les résultats ont mis en évidence l’importance des différentes étapes de traitement de l’information dans le calcul du bilan sédimentaire (réalignement des nuages de points séquentiels, évaluation de la bathymétrie, variabilité spatiale de l’incertitude altimétrique). L’exploitation des résultats a de plus montré un profond remaniement des chenaux tressés, du fait de l’occurrence de nombreuses avulsions. Dans un deuxième temps, les données LiDAR ont été utilisées pour caractériser la signature morphologique des lits en tresses à l’échelle plurikilométrique. L’analyse a porté sur un linéaire de plus de 25 km réparti sur 9 sites, dans les bassins versants de la Drôme, du Drac et de la Bléone. Premièrement, ces données mettent clairement en évidence l’effet du confinement de la tresse sur ses propriétés morphologiques avec entre autres un élargissement de la bande active à l'amont de ces zones. Deuxièmement, deux périodes caractéristiques ont été mises en évidence : autour de 3-4 et de 9-10 fois la largeur de la bande active. La période à 3-4 serait liée à la dynamique des macroformes. La période à 10 pourrait être liée à la dynamique de transfert à long terme des sédiments et pourrait correspondre aux successions longitudinales des mégaformes sédimentaires. Finalement, les données de LIDAR aérien ont été couplées à une étude diachronique de photographies aériennes pour reconstruire l'historique de formation des différentes unités spatiales composant la plaine d'inondation et relier cette structure avec les caractéristiques des unités de végétation. 3 rivières en tresses ont été étudiées dans les Alpes françaises avec un degré croissant d'activité : le Bouinenc, la Drôme et le Bès. Cette méthodologie a permis de reconstruire les différentes phases d'incision du lit avec deux périodes majeurs : avant 1948 et seconde partie du 20ème siècle. Il a aussi été montré l'impact des crues sur l'incision et l'élargissement de la bande active en lien avec le régime sédimentaire. Ces changements à long terme jouent un rôle significatif pour expliquer la mosaïque de la végétation de la plaine d'inondation avec une végétation bien développée et composée majoritairement d'unité matures dans le cas d'une rétraction et d'une incision sur le long terme. Les rivières plus actives présentent une diversité d'unité de végétation plus équilibrée. Enfin, la présence de lande arbustive semble être un bon indicateur des périodes d'incision. / Braided rivers form complex floodplains composed of sedimentary deposits mosaics, which differ in term of spatial and time scales, in function of hydrologic forcing and sediment supply. The goal of this thesis is to use airborne LiDAR to improve our understanding of braided channel morphological responses at different spatial and time scales.In a first time, two sequential airborne LiDAR surveys were used to reconstruct morphological changes of a 7-km-long braided river channel following a 14-year return period flood. This was done on the Bès River, a tributary of the Bléone River in southeastern France. Results highlighted the importance of different data processing steps in sediment budget computation (surface matching, bathymetry assessment, spatially distributed propagation of uncertainty). Analysis of these data also shows that the braided channel pattern was highly disturbed by the flood owing to the occurrence of several channel avulsions.In a second time, LiDAR data were used to look at longitudinal signatures of cross-sectional morphology at the scale of several kilometers. This study was done on 9 study reaches distributed on five braided rivers in Drôme, Drac and Bléone catchments. These data highlighted the effect of braided river confinement/obstruction on morphologic signature with upstream widening pattern. Secondly, two characteristic wavelengths have been identified from these signals: 3-4 and 10 times the active channel width. The first could be link to the dynamics of macroforms. The second could be associated to the dynamics of megaforms and long term sediment transfer.Finally, airborne LiDAR data were associated with archived aerial photos to reconstruct floodplain formation and relate this geomorphic organisation with vegetation patch characters. This is achieved on 3 different braided rivers in French Alps with an increasing degree of activity: the Bouinenc Torrent, the Drôme River and the Bès River. This methodology allowed us to establish the timing of channel incision with the identification of two major periods: before 1948 and second part of 20th century. Impacts of flood history on channel incision and widening pattern were also highlighted. These long term changes are playing a significant role to explain vegetation mosaics with a well-developed vegetated floodplain mainly composed of mature units following long term narrowing and incision. Rivers with higher activity show an equi-diversity of floodplain vegetation units. Finally, presence of shrubland patches seems to be good indicator of incision periods.

Les modèles de métapopulations permettent de prédire l'occupation des habitats au sein desquels elles évoluent en fonction de la configuration spatiale du paysage. La destruction et la création d'habitats peuvent induire une dette d'extinction ou un crédit d'immigration, c'est-à-dire des dynamiques d'espèces qui ne sont pas immédiates mais décalées dans le temps par rapport cette rotation des habitats. La présence d'un délai temporel signifie que les espèces ne sont pas à l'équilibre avec les paysages actuels. Cette thèse a pour objectif d'évaluer l'apport de modèles de métapopulations hors équilibre pour comprendre ces dynamiques décalées dans le temps de façon théorique et à partir de données empiriques sur les plantes forestières. A ces fins, nous avons évalué la robustesse d'une méthode d'inférence de paramètres de dynamique de métapopulations hors équilibre, adaptée à l'échelle régionale. Elle a ensuite été appliquée sur des données contemporaines de plantes forestières et de séries temporelles de cartographies des forêts dans les départements de la Seine-et-Marne et de l'Eure-et-Loir. A partir des modèles utilisés, nous avons pu reproduire certaines caractéristiques de la répartition des espèces qui sont dues à l'évolution historique des surfaces forestières. En effet, certaines espèces sont plus fréquentes en forêt anciennes et d'autres en forêt récentes, ce qui s'explique en partie par les traits des espèces et leurs affinités pour des conditions environnementales spécifiques. A partir de projections à long-terme de leurs dynamiques, nous avons montré que les délais de réponse de ces espèces peuvent être de plusieurs siècles et dépendent fortement de la connectivité fonctionnelle des habitats. Des scénarios virtuels de rotation des habitats ont été simulés pour pallier l'analyse des seules zones d'études. Associé à des projections de dynamiques de métapopulations, qui permettent de contrôler les paramètres à étudier, nous avons testé l'importance relative de la distance de dispersion des espèces et de la configuration spatiale de la rotation des habitats sur ces dynamiques. Le temps de retour à l'équilibre des métapopulations ne s'explique pas uniquement par l'amplitude de la dette d'extinction ou du crédit d'immigration mais dépend aussi de ces deux facteurs. Ces résultats mettent en évidence l'importance d'approfondir nos connaissances sur les effets de perturbations successives qui rendent le retour théorique à l'équilibre des espèces très incertain. / Metapopulation models are used to predict the occupancy of habitats from landscape spatial configuration. Habitat destruction and creation can lead to an extinction debt or an immigration credit that are time-delayed species dynamics following habitat turnover. Such delays mean that species are not in equilibrium with the current landscape structures. The aim of this thesis is to evaluate the contribution of non-equilibrium metapopulation models to understand time-delayed dynamics theoretically and from empirical datasets about forest plants. For this purpose, we assessed the robustness of the method used to infer metapopulation parameters at the regional scale. Then, we applied this method from contemporary plant inventories and time-series of forest maps of the Seine-et-Marne and the Eure-et-Loir french regions. Models satisfactorily reproduced some characteristics of forest plant spatial structure that are due to historical changes in forest areas. Indeed, some species are more frequent in ancient forests and some others are more frequent in recent forests notably due to species traits and their affinity for specific environmental characteristics. From long-term projections of species dynamics, we showed that the delays in forest plant dynamics are several centuries following habitat turnover and strongly depend on habitat functional connectivity. Virtual scenarios of habitat turnover were simulated to assess other study cases than the two study areas. We projected metapopulation dynamics, while controlling for some metapopulation parameters, to test the relative effects of species dispersal distance and the spatial configuration of habitat turnover on these dynamics. Metapopulation return time towards equilibrium not only depends on the magnitude of the extinction debt or on the magnitude of the immigration credit but also on these two variables.These results put forward the need to improve our knowledge on the effects of successive perturbations that make species return towards equilibrium unsure.