名古屋大学年代測定総合研究センターシンポジウム報告

For the first time, Mid-Late Holocene insect fossil assemblages were studied from inland northern Sweden, producing new evidence relating to both natural environmental changes and human impacts. The insect fossil assemblages from natural deposits indicated extensive woodland with old and dead wood and a deep litter layer of decaying matter. Human impacts became apparent from the 1st millennium AD, when the landscape around many sites became more open, with elements of heath. It is difficult to determine whether these changes were driven purely by human activity, indicating subtle landscape change as a result of periodic exploitation, or if natural influences were significant in creating this landscape structure. If connected with human use, then the impacts of periodic exploitation can be seen to be subtle and localised, but notable enough to leave tell-tale signs in the insect fossil record. These relatively subtle changes in the environment can be compared with the more severe effects found during periods of historically known permanent settlement, where extensively open and disturbed habitats are suggested in the insect fossil record. Species associated with arable and pasture land are restricted to the last few hundred years, in association with settled occupation. The climate signal in the insect fossil record has been weak, and use of the Mutual Climatic Range method (MCR) has not revealed evidence of climatic fluctuations during the Late Holocene period.

This research aims to understand the natural and human influences on erosion in three tributary watersheds to the Mekong River, Yunnan Province, China and to assess the utility of a novel application of isotopic indicators of erosion. It explores how erosion varies through time and space as a function of physical characteristics of the landscape, tectonic forces, and human alteration of the landscape for forestry and agriculture. To accomplish these goals, I use four sediment-associated radionuclides: in situ 10Be, meteoric 10Be, 210Pbex, and 137Cs. These isotopes accumulate in or on sediment grains, and each accumulates to a different depth on the landscape and has a different half-life. Thus, the isotopes can be used to track sediment as it moves across Earth's surface, each providing unique insight into processes occurring over a certain time period (from ~50 to 50,000 years) or eroding to a certain depth on the landscape. The studied watersheds range from 22° to 27° N latitude, and from 200 to 2500 km2 in area. I collected 54 samples of river-borne sediment within the three study watersheds, and measured the concentration of each isotope in every sample. In addition to the measured isotopic concentrations, I utilize on over 20 years of daily sediment yield data at the outlet of each watershed, hillslope steepness, normalized channel steepness (ksn), contemporary land-use data, elevation, and 56 years of mean annual precipitation data (MAP). Long-term erosion rates scale with topographic parameters in two of the three study basins, indicating that topography, or the underlying tectonic forces responsible for topography, control erosion rates over the past 6,000 to 50,000 years. Isotopic data also show that contemporary erosion is higher in cultivated areas than un-cultivated areas, a direct result of agricultural practices. Contemporary sediment yield, however, has not increased notably due to land-use change; however, under-representation of large stochastic events and sediment trapped by agriculture have reduced sediment yield relative to the long-term average in two of the studied watersheds. Overall, the data imply changes in contemporary erosion that are consistent with Chinese policies that promoted deforestation from the 1950's to the late 1980's and conservation from the late 1990's to present. This proves to be a significant finding, as the result of the top-down approach China has taken with conservation policy has been widely called into question in previous studies. While each isotope has the potential to provide unique information regarding erosional processes, in situ 10Be and 210Pbex proved to be the most useful, while meteoric 10Be was the most challenging to utilize. Though interpretation is complex, measuring all four isotopes on the same sediment samples helps to fully realize the potential of in situ 10Be to estimate background erosion by simultaneously allowing for assessment of contemporary and human induced erosion.

Paramo is the name of the region encountered in the upper belt (3 000m - 4 800m) of the Andean mountain ridges from Venezuela to the North of Peru. Paramo ecosystem occupies only 2% of the area of those countries. Nevertheless, paramo flora is the richest high mountain flora of the world (over 3500 species, 60% of endemism). High mountain region of the Northern Andes were almost uninhabited until the arrival of the Conquistadores. At the time of the conquest, livestock and new crops were introduced to the Andean ecosystems. Since that time, paramo has been used mainly for extensive cattle grazing and cultivation of potatoes and onions. During the last three centuries an abrupt intensification of the agricultural practices has occurred. The main aim of this study is to investigate the effects of human intervention, by mean of farming, on species diversity of the paramo vegetation. The study area was selected in the paramo belt of Santurban, Colombian Eastern Cordillera. Ordination techniques were applied to analyze the relation between plant species composition, environmental variables and management variables. We found plant species diversity is influenced by cattle grazing and cropping, but the vegetation changes are mainly determined by the altitudinal gradient. Intensity of human impact is also...

Alterations to the land surface can be attributed to both human activity and natural variability. Human activities, such as urbanization and irrigation, can change the conditions of the land surface by altering albedo, soil moisture, aerodynamic roughness length, the partitioning of net radiation into sensible and latent heat, and other surface characteristics. On the other hand, natural variability, manifested through changes in atmospheric circulation, can also induce land surface changes. These regional scale land surface changes, induced either by humans or natural variability, can effectively modify atmospheric conditions through land-atmosphere interactions. However, only in recent decades have numerical models begun to include representations of the critical processes driving changes at the land surface, and their associated effects on the overlying atmosphere. In this work we explore three mechanisms by which changes to the land surface–both anthropogenic and naturally induced–impact the overlying atmosphere and affect regional hydroclimate. The first land-atmosphere interaction mechanism explored here is land-use and land-cover change (LULCC) due to urban expansion. Such changes alter the surface albedo, heat capacity, and thermal conductivity of the surface. Consequently, the energy balance in urban regions is different from that of natural surfaces. To evaluate the changes in regional hydroclimate that could arise due to projected urbanization in the Phoenix–Tucson corridor, Arizona, my first study applied the Weather Research and Forecasting (WRF) with an Urban Canopy Model (UCM; which includes a detailed urban radiation scheme) coupled to the Noah land surface model to this region. Land-cover changes were represented using land-cover data for 2005 and projections to 2050, and historical North American Regional Reanalysis (NARR) data were used to specify the lateral boundary conditions. Results suggest that temperature changes are well defined, reflecting the urban heat island (UHI) effect within areas experiencing LULCC, whereas changes in precipitation are less certain (statistically less robust). However, the study indicates the likelihood of reductions in precipitation over the mountainous regions northeast of Phoenix and decreased evening precipitation over the newly urbanized area. The second land-atmosphere interaction mechanism explored here is irrigation which, while being an important anthropogenic factor affecting the local to regional water cycle, is not typically represented in regional climate models. In this (second) study, I incorporated an irrigation scheme into the Noah land surface scheme coupled to the WRF model. Using a newly developed water vapor tracer package (developed by Miguez-Macho et al. 2013), the study tracks the path of water vapor that evapotranspires from the irrigated regions. To assess the impact of irrigation over the California Central Valley (CCV) on the regional climate of the U.S. Southwest, I ran six simulations (for three dry and three wet years), both with and without the irrigation scheme. Incorporation of the irrigation scheme resulted in simulated surface air temperature and humidity that were closer to observations, decreased the depth of the planetary boundary layer over the CCV, and increased the convective available potential energy. The results indicated an overall increase in precipitation over the Sierra Nevada Range and the Colorado River Basin during the summer, with water vapor rising from the irrigated region moving mainly northeastward and contributing to precipitation in Nevada and Idaho. The results also indicate an increase in precipitation on the windward side of the Sierra Nevada Range and over the Colorado River Basin. The former is possibly linked to a sea-breeze type circulation near the CCV, while the latter is likely associated with a wave pattern related to latent heat release over the moisture transport belt. In the third study, I investigated the role of large-scale and local-scale processes associated with heat waves using the Modern Era-Retrospective Analysis for Research and Applications (MERRA) reanalysis, and evaluate the performance of the regional climate model ensemble used in the North America Regional Climate Change Program (NARCCAP) in reproducing these processes. The Continental US is divided into different climate divisions (following the convention of the National Climate Assessment) to investigate different mechanisms associated with heat waves. At the large scale, warm air advection from terrestrial sources is a driving factor for heat waves in the Northeast and Midwest. Over the western United States, reduced maritime cool air advection results in local warming. At the local scale, an antecedent precipitation deficit leads to the continuous drying of soil moisture, more energy being partitioned into sensible heat flux and acting to warm surface air temperatures, especially over the Great Plains. My analysis indicates that the NARCCAP simulated large-scale meteorological patterns and temporal evolution of antecedent local-scale terrestrial conditions are very similar to those of MERRA. However, NARCCAP overestimates the magnitude and underestimates the frequency of Northeastern and Midwestern US heat waves, partially due to anomalous heat advection through large-scale forcing. Overall, the aforementioned studies show that utilization of new parameterizations in land surface models, such as the urban canopy scheme and the irrigation scheme, allow us to understand the detailed physical mechanisms by which anthropogenic changes in the land surface can affect regional hydroclimate, and may thus help with informed decision making and climate adaptation/mitigation. In addition to anthropogenic changes of the land surface, humans are of course affecting the overlying atmosphere. Currently, NARCCAP is the best available tool we have to help us understand the effects of changes greenhouse gas induced climate change at the regional scale. The regional climate models participating in NARCCAP are able to realistically represent the dominant processes associated with heat waves, including the atmospheric circulation changes and the land-atmosphere interactions that drive heat waves. This lends credibility, when analyzing the projections of these models with increased GHG emissions, to the assessment of changes in heat waves under a future climate.

Landscape transformation that occurred during the Middle Ages in western and central Europe is reflected in all pollen diagrams. An event that was so striking and widespread was used by Firbas to distinguish a biostratigraphical period called the Younger Subatlantic (zone X; Firbas 1949). High Medieval landscape transformation is connected with rapid colonization in our area that resulted in extensive deforestation and intensified agriculture. During the first half of the 13th century, the settlement network was already stabilized and was very similar to the current state and was reaching also mountain areas (Klápště 1994). New organization and changes in land ownership, as well as a need for more effective agriculture, resulted in the connecting of small fields into larger ones and in an increase of cultivated area (Klápště 2006). The use of the land was different, and for the first time complete (Bakels 2009). During a few centuries anthropogenic factors that were enormously enhanced throughout the 13th century, formed a cultural landscape that was much more similar to the landscape of today than to the landscape of, for instance, the 9th century. This doctoral thesis is focused on the Early Medieval landscape in the Czech lands and its transformation that culminated during the 13th and 14th...

Los bosques del Sur del Ecuador tienen un alto valor para la conservación puesto que están muy amenazados pero también poseen altos niveles de biodiversidad y endemismo. Sin embargo, como el proceso de conservación es inherentemente espacial, la baja disponibilidad de información espacial acerca de los factores que promueven la vulnerabilidad de estos bosques y acerca de la distribución espacial de los objetivos de conservación ha provocado varios obstáculos para la conservación de los mismos. El objetivo principal de esta tesis fue generar información espacial acerca de las amenazas y los valores biológicos que ocurren en esta región para priorizar áreas de conservación. El segundo capítulo analizó los patrones de deforestación y fragmentación en la región desde 1976 usando fotografías aéreas e imágenes satelitales para identificar las áreas de bosque remanente, los frentes de deforestación, las tasas anuales de deforestación y las dinámicas de la composición y configuración del paisaje del Sur del Ecuador. Se registraron tasas anuales de deforestación de 0.75% (1976 – 1989) y 2.86% para dos periodos consecutivos. Se encontró también que el Sur del Ecuador está bajo un creciente proceso de fragmentación debido al incremento en el número de parches, el decremento en el tamaño promedio de los parches y el incremento en el aislamiento de los parches. Este estudió también contribuyó al mejor entendimiento de las dinámicas de cambio de los bosques tropicales. Se registró que la mayor superficie de bosque natural fue degradado o convertido a pastizales y que los principales frentes de deforestación están localizados en las zonas de bajas altitudes en los bosques siempreverdes premontanos. El tercer capítulo describe los patrones espaciales y temporales de la presión humana, debido a que este es uno de los principales factores que influencian la efectividad de las estrategias de conservación. Para esto se adaptó el Índice de Impacto Humano (HF) generado por Sanderson et al. (2002) y así evaluar los cambios espaciales en el HF durante 26 años a nivel de paisaje y de ecosistema. Esta información permitió identificar algunos “hotspots de cambio” y las áreas con menor influencia para de esta forma evaluar como los diferentes factores humanos contribuyen al HF y demostrar cuan efectiva ha sido el área protegida más importante de la región para reducir la presión humana al interior y exterior de sus límites. Los resultados muestran un notable incremento en los niveles de presión humana en el Sur del Ecuador y un decremento en el número de áreas sin influencia. Se identificó también que uno de los más importantes “hotspots de cambio” está localizado en la región occidental del área de estudio y en la cuenca baja del Río Zamora. Los tipos de vegetación con mayor influencia humana fueron los bosques secos estacionales y los matorrales en donde la densidad de la población fue el principal factor humano que contribuyó a los niveles de presión humana observados. Finalmente, se encontró que el Parque Nacional Podocarpus ha sido parcialmente efectivo para reducir la presión humana en su interior y exterior, puesto que los niveles de HF se incrementaron al interior del área protegida y en el área buffer pero fueron menores a los observados en las áreas circundantes. El cuarto capítulo analizó los patrones de diversidad alfa y beta de plantas endémicas para evaluar la congruencia entre ambos patrones e identificar áreas con prioridad para ser conservadas. Se encontró que el “hotspot” de diversidad alfa para las plantas endémicas está localizado en los Andes y que es poco congruente con las zonas que muestran los más altos niveles de diversidad beta, los cuales están concentrados mayormente en las estribaciones orientales y occidentales de los Andes y en las cordilleras costeras y amazónicas. También se encontró que aproximadamente 40% de la superficie con altos niveles de diversidad alfa y beta ha desaparecido debido a la deforestación y que solo el 30% remanente está bajo alguna categoría de conservación. De esta forma se proponen 12 áreas potenciales con alta prioridad para la conservación, las cuales mayormente esta localizadas en el Sur del Ecuador, para de esta forma mejorar la representatividad y complementariedad de la actual red de reservas. Finalmente, el quinto capítulo analiza los principales hallazgos de esta investigación remarcando las implicaciones para la conservación y sugiriendo áreas potenciales para ser conservadas con base a los niveles de presión humana, vegetación remanente y patrones de diversidad alfa y beta de plantas endémicas en la región Sur del Ecuador.

As tartarugas na Amazônia são particularmente sensíveis à pressão humana, já que os impactos nas áreas de nidificação podem afetar negativamente a taxa de reprodução das populações. A seleção do local de nidificação é um componente fundamental para o sucesso de desova, no entanto, a associação entre a escolha do local e a aptidão do local escolhido ainda é pouco estudada. Neste trabalho testamos um conjunto de variáveis para explicar os padrões de nidificação em Tracajás (Podocnemis unifilis), com base em dados coletados em 73 locais de nidificação ao longo de 118 km de rio na Amazônia Oriental Brasileira. Modelos lineares generalizados (GLMs) foram usados para avaliar as influências antropogênicas e ambientais nos padrões de seleção do local de nidificação (número de ninhos, densidade de ninhos, distância do ninho à água e variação na distância à água) e adequabilidade do local de nidificação (remoção de ninhos por humanos). Como resultado, encontramos que o número e densidade de ninhos foram fortemente explicados por variáveis ambientais, e a distancia do ninho á água diminuiu com a proximidade as casas. A remoção humana foi o principal responsável pela perda de ninhos (47% dos ninhos foram removidos) principalmente nos trechos do rio com maior atividade humana. Nossos dados sugerem que mudanças antropogênicas estão levando a diferenças entre a escolha de local de nidificação e a sua adequabilidade, assim, nos rios onde humanos tem maior acesso, sinais usados pelas fêmeas para selecionar áreas de nidificação não estão permitindo desovas bem-sucedidas. Ao contrário das previsões nas hipóteses, os achados demonstram que as fêmeas não parecem evitar desovar em locais perigosos e inadequados. Portanto, ações diretas, como a proteção de áreas de nidificação, são vitais para a conservação das tartarugas na Amazônia. / Amazonian freshwater turtles are particurlarly sensitive to human pressure, since impacts on their nesting areas can negatively affect reproductive rate of populations. Nest-site selection is a fundamental component of freshwater turtle nesting success, however, linking oviposition choices to overall suitability of nest-site selection remains poorly tested. We tested a set of variables to explain nesting patterns in the yellow-spotted river turtle (Podocnemis unifilis), based on data collected from 73 nesting sites along 118 km of river in the eastern Brazilian Amazon. General Linear Models (GLMs) were used to evaluate anthropogenic and environmental influences on patterns in nest-site selection (four responses: number of nests, nest density, distance from nest to water and variation in distance to water) and nest-site suitability (removal of nests by humans). Number and density of nest were largely explained by environmental variables, and distance from nest to water decreased with the proximity to human habitations. Human removal of nests was the primary driver of nest failure (47% of the nests were removed) and removal was higher in sections of river with higher human activity. We show that anthropogenic changes are driving differences between nest-site selection and suitability, whereby the signals used by females to select nesting areas no longer enable successful nesting along rivers accessible to humans. Contrary to predictions from the hypotheses, our findings demonstrate that females do not appear to avoid nesting in dangerous and unfit sites. Therefore, direct actions including the protection of nesting areas are vital for the conservation of Amazonian freshwater turtles.

La variabilité spatio-temporelle de l’évolution morpho-sédimentaire du fond de la vallée de la Choisille (bassin versant : 288 km²), affluent de la Loire moyenne dans le sud-ouest du Bassin parisien (37), a été étudiée par 78 forages (8 transects), prospection géophysique, analyses sédimentologiques et datations 14C et OSL. Huit phases d’évolution du système fluviatile depuis le début Weichsélien ont été définies et corrélées avec les données palynologiques et archéologiques locales, afin de comprendre l’impact des facteurs forçants : climat ou/et anthropisation. Du Weichsélien jusqu’au début du Subatlantique, l'activité d'incision ou de sédimentation de la Choisille a évolué sous contrôle climatique strict. Depuis l’Allerød, cette évolution a été différente de celles observées sur d’autres rivières en Europe du Nord-Ouest, indiquant des spécificités climatiques et géologiques régionales. Dès l’Âge du Bronze, la rivière a évolué sous contrôle climatique et anthropique ; l'impact anthropique sur la sédimentation fut prépondérant, mais très variable dans le temps et l'espace au sein du bassin selon les potentialités agricoles des secteurs considérés. / The spatio-temporal variability of the Choisille valley morpho-sedimentary evolution (catchment: 288 km²), a tributary of the middle Loire River in the south-western Parisian Basin (37), was studied through 78 core-drillings (8 transects), geophysical prospecting, sedimentological analyses and 14C and OSL dating. Eight phases of fluvial system evolution were defined and correlated with palynological and archaeological dataset, in order to highlight the impact of forcing factors: climate and/or human activity. From the Weichselian up to the Subatlantic, the fluvial incision or sedimentation activity has strictly evolved under climate control. Since the Allerød, this evolution was different from what has been observed on other rivers of north-western Europe, indicating regional climatic or geological specificities. Since the Bronze Ages, the river has evolved under climatic and human control; the anthropogenic impact on sedimentation was dominant, but spatio-temporaly variable in the catchment, in relationship with the agricultural potentialities of the different areas.

With visitation to natural areas increasing, the appropriate management of these areas is important. There are a number of management tools available which endeavour to minimise environmental impacts of visitors. One such management tool is interpretation. Interpretation is widely used as a management tool because: it is perceived to be the most cost effective method; it is a light-handed approach and allows visitors the freedom of choice; and it enhances visitor experiences and satisfaction. However, the ability of interpretation to bring about a reduction in the impacts of visitors to natural areas, has rarely been quantified. This study was designed to determine the extent to which an interpretive program reduced the environmental impacts of visitors to national parks. Fieldwork was undertaken in Lamington National Park, where 41 guided walks were examined. To measure the actual behaviour or resulting impacts of visitors in a national park, three appropriate environmental indicators were chosen: shortcutting of corners, picking up litter already on the track, and noise levels. Five interpretive programs were created, each with a different combination of environmental interpretation, role modelling and verbal appeals. For the shortcutting results, the interpretive program with the combination of environmental interpretation, role modelling by the guide and verbal appeals from the guide, was always the most effective in reducing shortcutting. Visitors in this interpretive program were always, statistically, less likely to shortcut than visitors on all the other interpretive programs. The programs with only environmental interpretation or no environmental interpretation, were always least effective in reducing shortcutting. The interpretive programs with environment interpretation plus role modelling, or verbal appeals, were always in the middle of these extremes. They were more effective than having neither role modelling or verbal appeals, but less effective than having both. Results for the amount of litter picked up found that the inclusion of verbal appeals in an interpretive program was the only factor that influenced whether visitors picked up litter. In addition, there was no difference in the amount of litter picked up, by the interpretive program with environmental interpretation only, and the program with no environmental interpretation. Results for the noise levels of visitors, found that no interpretive program reduced the amount of shouting and talking loudly of visitors. Although not statistically significant, it did appear that there were lower proportions of shouting and talking loudly, following a verbal appeal and/or role modelling. Additionally, there was no influence of the interpretive program on the proportion of time visitors were talking, or quiet, during their walk. Overall, this research found that interpretation can be an effective management tool in reducing visitor impacts. Interpretation is most effective in reducing impacts when those impacts are specifically addressed through verbal appeals, combined with positive role modelling of appropriate behaviours. However, interpretation did not reduce all the impacts studied and therefore is not the solution to all problems. Implications of this study are that those using interpretation as a means of reducing visitor impacts, must ensure that they have a high standard of interpretation, which specifically addresses the impacts that need to be reduced. It also highlights the importance of the role of the guide, and that those employed should be well trained and competent in their position.