1,219 research outputs found
Annette Harvey Diary, 1906-1910
No full textAnnette Harvey, of Arkansas, West Virginia, and Ohio, recounts events of her daily life in this 'Line a Day' diary. She was the daughter of William Hope Harvey, aka 'Coin' Harvey, a well-known businessman, politician, author and founder of the resort of Monte Ne and the Ozark Association. Annette's brief entries record visits, housework, dances, parties, a train trip to New York, weather, church services and socials over a 5 year period, 1906-1910. Addresses and miscellaneous thoughts, quotations, poems, are recorded at the end of the volume. A photograph of her home made in 1906 is tipped in at the front of the diary
Interview with Annette Lareau
No full textAnnette Lareau is the Stanley I. Sheerr Professor in the Department of Sociology at the University of Pennsylvania. She is the author of Unequal Childhoods: Class, Race, and Family Life (University of California Press). Unequal Childhoods won the best book award from three sections of the American Sociological Association: Sociology of the Family, Sociology of Children and Youth, and Sociology of Culture (co-winner)
Interview with Annette J. Smith
No full textInterview in seven sessions, December 2010 to January 2011 with Annette J. Smith, visiting professor of French at Caltech from 1970 to 1982, appointed associate professor with tenure in 1982, promoted to professor of French in 1985, and Professor of Literature emeritus since 1993.
Family history, childhood and education in Algiers, Algeria. Family history and background of late husband, Caltech Professor of Literature David R. Smith (1960-1990). Bachelor’s degree in Classics (1948) from Sorbonne in Paris. Attended the School of Professors of French Abroad at the Sorbonne and taught at the University of Wales in Swansea. Master’s degree in English. Marriage to D. Smith and move to the United States.
Teaches at Scripps College and Claremont Men’s College [now Claremont McKenna College], where she had tenure position. Caltech hires D. Smith as professor and A. Smith as lecturer in French language. D. Smith as Joseph Conrad scholar. Doctorate degree (1964) and dissertation on author Nicole Védrès. D. Smith made Master of Student Houses (1969-1975); life in Virginia Steele Scott house. Descriptions of faculty and atmosphere within Division of Humanities and Social Sciences (HSS), beginning when Hallett Smith was chair. Friendship with Max and Manny Delbrück. Cultural life at Caltech; D. Smith brings poets, actors, directors and musicians to campus. Life as professor’s spouse and efforts to improve working conditions and salaries for female staff. Sexual discrimination in HSS and support for Jenijoy La Belle. History and founding of Baxter Art Gallery (1970), significant exhibitions organized by D. Smith, closing of Baxter Art Gallery (1985). Important relationships with Caltech professors, postdocs and staff: R. Sperry, R. Feynman, A. Hibbs, J. and F. Audouze, D. and C. Cesarsky, J.-P. Bibring, and N. and C. Corngold.
Elevated to associate professor (1982). Literature courses she taught and impressions of students. Two books accepted for publication: one on Arthur de Gobineau and translation of poems by Aimé Césaire. Explanation of racial theories of Gobineau and discussion of his fiction; impact of Gobineau’s racist writings and theories, including appropriation by Nazis. Discussion of Darwinism. Comments about translating poetry and working with poet Clayton Eshleman on four books of Césaire’s poetry. Description of Césaire’s life and politics and his importance as a leader and author. Reads her translations of Césaire’s poems.
Impressions of foreign language study at Caltech and further descriptions of HSS, including some unfortunate hires and tension in the division. D. Smith’s illness and death. Teaching in Papeete, Tahiti, 1990-1991. Circular nature of her life and work. Purchase of land and building of second home in Point Dume, Malibu, (1980-1981) and celebratory party there. Expressions of gratitude for Caltech and its brilliant scientists and community
The censor without, the censor within: the resistance of Johnstone’s improv to the social and political pressures of 1950s Britain
No full textKeith Johnstone's improv, popularly known through the Theatresports format, was forged in the cultural and historical context of 1950s Britain. In this paper I will argue that Johnstone's incarnation of theatrical improvisation was defined by its reaction to the normalising forces exerted by the social elite upon the broader population and by civilised society upon the individual.
Johnstone's improv was a reaction against the Lord Chamberlain’s power to censor the British stage and a challenge to the internalised 'censor' British society of the time implanted in the minds of his students, stunting their creative imaginations. Johnstone borrowed elements of professional wrestling to break down the regimented conventions of the theatre space and enliven the spectator-performer relationship. As well as echoing Roland Barthes’ idealistic analysis of professional wrestling (Barthes, 1984: n.p.), Johnstone’s improv shares Barthes’ critique of the authority of the author and allows meaning to be generated out of the encounter between performers and spectators in the instant of the performance’s emergence. Through these processes, Johnstone’s improv defies the censor without (The Lord Chamberlain) by rooting out the censor within (the socially learnt inhibitions to the creative imagination).
By delineating the political and social pressures at play in the historical context of 1950s Britain and the ways that the stylistic conventions of Johnstone's improv resist and subvert these forces, I will demonstrate the emancipatory power latent in this mode of popular performance. This is a particularly timely analysis given the increasing authority of free market economics to dictate what appears on contemporary British stages, and the internalised censor that panoptical CCTV and social media is implanting within the minds of British citizens today
Process-based characterization of the soil carbon balance in hardwood floodplain forests of the lower middle Elbe River
No full textI assessed key drivers for processes in the soil carbon (C) balance of hardwood floodplain forests at the lower middle Elbe River. Floodplains play a significant role in the global C cycle, particularly due to their soil organic carbon (SOC) storage potential in hardwood floodplain forests. In floodplains, C input occurs from deposition of dead plant debris and fluviatile sediments. C losses are mainly driven by flood-induced soil erosion and SOC mineralization. These processes vary by relief position and vegetation type. However, anthropogenic landscape modifications have affected the natural flooding regime and the vegetation composition. The interaction between natural conditions and anthropogenic modifications complicate the understanding of processes in the C balance of hardwood floodplain forests. To determine the driving mechanisms for these processes, I selected 50 floodplain study sites along the lower middle Elbe River and categorized them into hydrologic situation (low and high relief position; active and former flooding zone) and vegetation type (forest and grassland; old and young forest). The aim of my dissertation is to understand the processes controlling the soil C balance of hardwood floodplain forests.
To characterize the processes controlling the soil C balance of hardwood floodplain forests, I related SOC stocks, SOC stability, and soil CO2 efflux (through autotrophic and heterotrophic soil respiration) to vegetation (e.g., forest age, basal area) and soil characteristics, particularly pedological traits (e.g., hydromorphic features, soil texture, pH, C/N ratio). SOC stocks were determined up to a depth of 1 m and compared to topsoil SOC stocks. SOC density fractions, SOC mineralizability and microbial biomass in top- and subsoils were analyzed to identify drivers for SOC stability. Soil CO2 effluxes were measured over a full year using the closed-chamber method. Based on the response of soil CO2 efflux to soil moisture and temperature, annual rates were determined. Additionally, the applicability of a low cost CO2 sensor (K33SOIL) for in situ soil measurements was tested to improve the spatial and temporal resolution of soil CO2 flux studies.
SOC stocks were unaffected by vegetation type (grassland and forest) but greatest in low relief position and in the active flooding zone. SOC stocks ranged between 99–149 t ha-1 and were thereby similar to other temperate hardwood floodplain forest but also larger than terrestrial forests. SOC stocks in low lying forests of the active flooding zone were 50% greater compared to high elevated forests and to hardwood floodplain forests of the former flooding zone. Fine soil texture (< 6.3 µm) was the most important univariate predictor for SOC stocks, followed by flooding duration. A multiple linear regression showed that fine texture, pH, C/N ratio and forest age explain 86% of variance in SOC stocks. Consequently, fine texture was the most important driver for SOC stabilization to organomineral complexes, explaining 43–64% of variance in mineralizable C and the heavy density fraction (HF) of SOC. The HF was the most important SOC pool (contributing > 64% in top- and subsoil) and further confirmed the importance of fine texture for SOC storage. Thus, SOC stocks and SOC stabilization were strongly controlled by proxies for floodplain relief and sedimentation processes, such as flooding duration and fine soil texture.
Soil CO2 efflux ranged between 1006–2209 gC m 2 y 1 (corresponding to 10–22 t ha 1 y 1) and was also closely related to fine texture and soil pH (R2 = 0.75), confirming a close relationship between the C balance and relief-affected features. Soil CO2 efflux was decreased at high pH (i.e., close to neutral). This result fits with the finding that SOC stocks were greatest at high pH. The largest total soil CO2 efflux occurred on sites, with highest fine texture content. This seems to contradict with the finding, that fine texture is the main driver for SOC storage. However, this effect was related to an indirect positive effect of fine texture on soil moisture and SOC content, which are important for microbial mineralization and root vitality. Total soil CO2 efflux occurred thereby partly in amounts comparable to tropical forests. Relative soil CO2 efflux (in gCO2-C gSOC-1 y-1) revealed that the smallest efflux occurred in low lying sites, where largest SOC stocks and fine texture contents occur. These sites where also represented by greatest pH and hydromorphic features appearing close to the soil surface. These results again suggest that SOC is protected by oxygen scarcity and stabilization to fine soil particles in low lying forests. To cover further CO2 flux measurements with high spatial and temporal resolution, I approved the applicability of a low cost CO2 sensor module in precision and accuracy in floodplain soils.
To sum up, the process-based soil C balance in hardwood floodplain forests of the lower middle Elbe River was mainly controlled by properties representing the hydrologic situation, such as fine soil texture, soil pH and C/N ratio, the depth of hydromorphic features, and flooding duration. These findings indicated that oxygen scarcity, allochthonous C input, and SOC stabilization through the accumulation of fine soil particles are the main processes contributing to SOC preservation and mitigation of C loss through soil CO2 efflux in hardwood floodplain forests. Thus, hardwood floodplain forests act as more efficient C sinks once located in the active flooding zone where flooding and sedimentation processes occur.
My dissertation thereby provides important information that should be considered during floodplain management. Furthermore, my studies underline the importance of hardwood floodplain forests as a considerable SOC reservoir but also highlight the relevance of the hydrologic situation for future climate change scenarios
Integrative Differentielle Relaxation (IDR) in der Psychotherapie – Möglichkeiten und Grenzen im dyadischen Setting
No full textIn der vorliegenden Arbeit wird der Ansatz der Integrativen Differentiellen Relaxation (IDR) unter Einbezug spezifischer Konzepte der Integrativen Therapie und aktueller stresstheoretischer Aspekte vorgestellt. Es erfolgt eine Standortbestimmung des IDR-Ansatzes bezüglich der allgemein üblichen Entspannungsverfahren wie bspw. Autogenes Training und Progressive Muskel-Relaxation. Die Spezifika des Ansatzes werden dargestellt und es wird der Frage von Möglichkeiten und Grenzen der Einbettung in das dyadische psychotherapeutische Setting nachgegangen. Hierbei wird insbesondere auf die Übertragungs- und Gegenübertragungsaspekte fokussiert, die es zu beachten gilt, wenn „übende Elemente“ in das psychotherapeutische Setting einbezogen werden. Die theoretischen Ausführungen werden durch ein Fallbeispiel aus der Praxis der Autorin ergänzt.This text discusses Integrative Differential Relaxation (IDR) in relation to specific Integrative Therapy and stress-theoretical aspects. It follows a localization of the IDR approach within traditional relaxation techniques such as autogenic training and Progressive Muscle Relaxation (PMR). The discussion outlines the specifics of IDR and addresses its options and limits within the dyadic psychotherapeutic settings. In particular it focuses on conceptual questions of transference and countertransference relative to exercising elements as part of psychotherapy.In conclusion the author applies the theory to a case study.https://www.fpi-publikation.de/polyloge/10-2008-frankenstein-anft-annette-integrative-differentielle-relaxation-in-der-psychotherapie/peerReviewedpublishedVersio
Das Verhalten von organischen Schadstoffe in Permafrost-beeinflussten Böden
No full textSoils and soil functions are a main resource for our existence on earth. But soils are under threat by degradation. Another resource that seems irreplaceable for human being on this planet is oil. Oil, as well as soil, is a non-renewable resource in relation to human life time. With decreasing reservoirs in the established oil production areas, remote oil resources, like in the Arctic, come into the focus of exploration activities (Bird et al. 2008). Exploration, transport and processing of oil inevitably cause accidental spills and continuous release of product and compounds into the soil on different levels. In general the reasons are technical inadequacy, human error or natural hazards (Siciliano et al. 2008).
Some studies found that the entry of organic contaminants in permafrost-affected soils led to an increase in active layer thickness and subsequent soil subsidence (Collins et al. 1993). In Antarctic soils the accumulation of PAHs from atmospheric deposition were found in the transient layer (Curtosi et al. 2007). To identify the processes responsible for organic contaminant migration in permafrost-affected soils a laboratory method to simulate the natural freezing process was invented and the distribution of different PAHs in oil contaminated soils at water unsaturated conditions were investigated.
Experiments were run with a closed column system in three parallels and a reference. The columns were cooled from the bottom or from the top. The freezing process was monitored in each column by two temperature probes and a TDR probe. A two-phase freezing scenario proved to be the best way to simulate the natural freezing process in different soils with the along going water migration processes.
Until now two main processes of organic contaminant migration dependent on the freezing process in soils have been identified. For organic contaminants that are present as a single phase, a pushing out of the soil pores forward the freezing front due to the freezing induced water migration and ice formation has been observed (Chuvilin et al. 2003). In conjunction with water soluble organic contaminants Konrad & Seto (1991) observed the exclusion of the organic contaminants from the forming ice. This process also leads to a contaminant accumulation ahead the freezing front.
The present studies could show a significant influence of the freezing process on the distribution of the 3-ring PAH anthracene in a water unsaturated sand contaminated with crude oil. Anthracene accumulated ahead the freezing front. An examination of anthracene fractions with different extractabilities revealed that the methanol-water extractable fraction was responsible for the anthracene decrease in the frozen part of the soil and the accumulation in the unfrozen part. The ethyl-acetate extractable fraction, which is mainly associated with the petroleum hydrocarbons did not show significant differences between the frozen and the unfrozen parts of the soil. This observation indicated that the exclusion of the anthracene from the forming ice was the process responsible for the PAH migration.
The 4-ring PAH pyrene did not show significant differences in its distribution within a silty soil after the freezing process. That was not expected, because the water solubility of pyrene is three times that of anthracene. However, it was supposed that increased water migration processes towards the freezing front may have masked migration processes of pyrene from the frozen towards the unfrozen part of the soil.
All together the results of the present studies could show that the freezing process leads to a dispersion of PAHs in water unsaturated soils with an along going fractionation of the contaminants. The specific properties of each PAH, especially log KOC, define the magnitude of the freezing induced migration process.Böden sind unsere Lebensgrundlage. Trotzdem sind sie ständig durch Degradation in Form von Schadstoffeintrag oder Erosion bedroht. Eine weitere, scheinbar unersetzliche Hauptgrundlage des menschlichen Daseins ist Erdöl. Sowohl Erdöl als auch Böden sind auf humane Lebenszeiträume gesehen nicht regenerative Rohstoffe. Mit steigendem Rohölpreis rücken schwer zu explorierende Ölvorkommen, wie z.B. in der Arktis, in den Fokus von Explorationsfirmen (Bird et al. 2008). Mit Exploration, Transport und Verarbeitung dieses Öls gehen jedoch unvermeidliche Verschmutzungen der Umwelt, insbesondere der Böden, einher. Im Allgemeinen liegen die Gründe für solche Verschmutzungen sowohl in technischen und menschlichen Fehlern als auch in nicht vollständig beherrschbaren, natürlichen Ereignissen (Siciliano et al., 2008).
Der Eintrag von organischen Schadstoffen in Permafrost-beeinflusste Böden kann zu einer Zunahme der Mächtigkeit der saisonalen Auftauschicht (active layer) und als Folge zu einer Absenkung des gesamten Bodens führen (Collins et al. 1993). In der Antarktis wurde eine Akkumulation von atmosphärisch eingetragenen PAK im Bereich der Permafrosttafel beobachtet (Curtosi et al. 2007). In der vorliegenden Arbeit wurde zuerst eine Methode zur Simulation des natürlichen Gefrierprozesses im wasserungesättigten Boden entwickelt, und dann der Einfluss des Gefrierprozesses auf die Verteilung von verschiedenen PAK in ölkontaminierten Böden untersucht.
Die Versuchsapparatur umfasste ein geschlossenes Säulensystem, welches mit drei Parallelen und einer Vergleichssäule betrieben wurde. Die Säulen konnten für verschiedene Fragestellungen von oben oder unten gekühlt werden. Der Gefrierprozess wurde mit jeweils zwei Temperatursonden und einer TDR-Sonde überwacht. Ein zwei-phasiges Abkühlprogramm mit einer schnellen ersten Abkühlphase und einer sehr langsamen, naturnahen, zweiten Abkühlphase zeigte die besten Ergebnisse der Simulation der natürlichen Wassermigrationsprozesse, die während des Gefrierprozesses im Boden stattfinden.
Bisher sind zwei Prozesse im Zusammenhang mit dem Gefrierprozess und der Verlagerung von organischen Schadstoffen in Böden bekannt. Zum einen das Auspressen von Schadstoffen aus den Bodenporen, wenn sie als eigene Phase vorliegen (Chuvilin et al. 2003) und zum anderen die Bildung sehr reiner Eisstrukturen unter Ausschluss von gelösten Substanzen bei sehr langsamen Gefrierraten (Konrad & Seto, 1991). Beide Prozesse führen zu einer Akkumulation von Schadstoffe direkt vor der Gefrierfront.
Mit den Versuchen der vorliegenden Arbeit konnte ein signifikanter Einfluss des Gefrierprozesses auf die Verteilung des 3-Ring PAK Anthracen in einem wasserungesättigten und mit Rohöl kontaminierten Sand dargestellt werden. Es fand eine Schadstoffakkumulation direkt unterhalb der Gefrierfront statt. Die genauere Betrachtung unterschiedlich extrahierbarer Anthracenanteile zeigte, dass durch den Gefrierprozess die Methanol-Wasser-lösliche Fraktion verlagert wird, während die stärker gebundene Ethylacetat-lösliche Anthracenfraktion keine signifikanten Änderungen zeigte. Diese Beobachtung weist auf den Ausschluss des 3-Ring PAK aus dem sich bildenden Eis hin und spricht gegen eine Verlagerung des Anthracen zusammen mit der vorhandenen Rohölphase.
Für das 4-Ring PAK Pyren konnten in einem schwach-tonigen Schluff keine signifikanten Verlagerungsprozesse aufgrund des Gefrierprozesses nachgewiesen werden, obwohl die Wasserlöslichkeit des Pyrens etwa dreimal so hoch ist, wie die des Anthracens. Aufgrund der erhöhten Wassermigration aus den ungefrorenen Bereichen des schach-tonigen Schluffs zur Gefrierfront hin, bleibt jedoch zu vermuten, dass sich Auswirkungen verschiedener Migrationsprozesse gegenseitig aufgehoben haben.
Die Ergebnisse dieser Arbeit haben gezeigt, dass der Gefrierprozess die Dispersion von PAK im wasserungesättigten Boden unterstützt, wobei es zur Fraktionierung der Schadstoffgruppe kommt. Die spezifischen Eigenschaften der einzelnen PAK, insbesondere der log KOC, bestimmen das Ausmaß der gefrierbedingten Migration der Schadstoffe
Wechselwirkungen zwischen Boden-Wasser-Dynamik und Hartholz-Auwald in der unteren Mittelelbe - Deutschland
No full textHardwood floodplain forests are one of the most biodiverse and productive ecosystems in Central Europe. They provide important ecosystem services as nature habitat, flood retention, runoff regulation, carbon storage, recreation and others. At the same time, they have been under threat since hundreds of years due to anthropogenic activities such as river channelization, diking and land use change to agricultural and grazing lands. Furthermore, recent and future effects of climate change comprise increased and more frequent droughts. They interfere with regular hydrologic fluctuations in hardwood floodplain forests, which are highly sensitive and dependent on the connection to the river hydrology. Processes specific to floodplains, like active sedimentation and groundwater fluctuations contribute to topographic and soil heterogeneity in this ecosystem. Soils play a pivotal role for the functioning and productivity of hardwood floodplain forests, as they regulate nutrient and water availability and contribute to the storage and stabilization of soil organic carbon. The overarching aim of this thesis is to understand how the heterogeneity of the floodplain landscape influences soil nutrient distribution and soil water availability, and analyze how these factors influence forest processes and productivity. Two different studies were conducted to achieve this aim.
In the first study, I investigated the influence of diking on the distribution of nutrients and soil formation processes in four defined hydrogeomorphic units (HGUs) that account for landscape heterogeneity (high and low sites) and hydrological connection (active and former floodplain). For this, mixed topsoil samples (0-10 cm of mineral soil) were collected in 44 hardwood floodplain forest sites (2500m2 each) along 150 km of the lower middle Elbe and 18 soil profiles were studied. Soil parameters as grain size distribution, pH, total carbon (TC), total nitrogen (TN), plant available phosphorous (Psol), cation exchange capacity (CEC) and base saturation (BS) were determined in the laboratory. Main results show that diking had a strong influence on floodplain nutrient availability. The active floodplain presented higher availability of Psol, which was related to higher soil pH values and most probably to the active sedimentation of riverine particulate matter and the input of soluble nutrients from the flooding water. Former floodplain soils acidified significantly and showed lower nutrient availability. This occurs in the absence of flooding that allows litter accumulation, decomposition and further soil development.
In the second one, I studied the sap flow velocity of five oaks (Quercus robur) and five elms (Ulmus laevis) under high evaporative demand and different soil water availability (high and low) in two active floodplain forest sites (sandy and loamy). In this study, continuous monitoring of soil water parameters as volumetric water content and water tension (at defined depths up to 1.6 m below ground), as well as micrometeorological parameters and tree sap flow velocity were performed during the vegetation period of 2020. The sap flow velocity of the trees was measured with self-built heat-ratio method devices at three positions per tree. This data was averaged for the five trees per species per site. Based on measured values of vapor pressure deficit and global radiation, I model potential sap flow under non-water-limited conditions by using the Jarvis-type model. The ratio between modeled and measured sap flow, under high and low water availability and for the sandy and loamy site, was analyzed against measured soil water tension to define the relevance of soil water on the sap flow velocity dynamics. Sap flow velocity in Elms was up to 100% higher than in oaks. However, under low water availability, high evaporative demand, and sandy texture, Ulmus laevis reduced sap flow velocity considerably. In comparison to Ulmus laevis, the Quercus robur displayed lower, but less variable sap flow velocities, and sensitivity to soil substrate and associated soil water storage by presenting 50% lower sap flow velocity in the sandy site compared to the loamy site. For Ulmus laevis, the ratio of measured and modeled sap flow against soil water potential showed that in the sandy site under low water availability, the measured sap flow deviates from potential sap flow, implying a reduction of sap flow velocity. In linear regressions, I show that soil water potential explains the sap flow velocity variability of Ulmus laevis.
Both studies point to the importance of considering the spatial complexity of soil properties and processes in floodplains for floodplain restoration measures, in particular concerning reforestation with hardwood species. I show that the nutrient distribution in the floodplain soils is driven by the connection to the river hydrology and that those sites that were disconnected do not display similar nutrient contents as those in the active floodplain. The active floodplain provides higher potential for hardwood floodplain forest restoration in terms of nutrient availability. In the active floodplain, soil water potential explains sap flow variability under periods of drought and in sand-dominated sites. Regarding species, Quercus robur appears to be more tolerant to drought stress and shows a higher adaptation to site conditions by lowering sap flow velocity under periods of water stress. Thus, this species may be better equipped to avoid problems like cavitation under the expected increase of drought events.Hartholzauenwälder gehören zu den artenreichsten und produktivsten Ökosystemen in Mitteleuropa und erbringen wichtige Ökosystemleistungen als Lebensraum, Hochwasserrückhalt, Abflussregulierung, Kohlenstoffspeicherung, Erholungsraum, weitere. Gleichzeitig sind sie seit Jahrhunderten durch anthropogene Aktivitäten wie die Kanalisierung und Eindeichung von Flüssen sowie die Umnutzung von Wald in Agrar- und Weideland bedroht. Darüber hinaus beeinträchtigen aktuelle sowie zukünftige Auswirkungen des Klimawandels wie zunehmende und häufigere Dürreperioden die regelmäßigen hydrologischen Schwankungen die Hartholzauenwälder, die sehr empfindlich und abhängig von der Anbindung an die Flusshydrologie sind. Auenspezifische Prozesse wie aktive Sedimentation und Grundwasserschwankungen tragen zur topografischen und pedologischen Heterogenität in diesem Ökosystem bei. Die Böden spielen eine zentrale Rolle für die Funktion des Ökosystems und die Produktivität von Hartholzauenwäldern, da sie die Verfügbarkeit von Nährstoffen und Wasser regulieren und zur Speicherung und Stabilisierung des organischen Kohlenstoffs beitragen. In dieser Arbeit soll untersucht werden, wie sich die Heterogenität der Auenlandschaft auf die Nährstoffverteilung und die Wasserverfügbarkeit im Boden auswirkt und wie diese Faktoren die Prozesse im Wald und dessen Produktivität beeinflussen. Um dieses Ziel zu erreichen, wurden zwei verschiedene Studien durchgeführt.
Die erste Studie behandelt den Einfluss der Eindeichung auf die Nährstoffverteilung und die Bodenbildungsprozesse in vier definierten hydrogeomorphen Einheiten (HGUs), die die landschaftliche Heterogenität (Hoch- und Tieflagen) und den hydrologischen Zusammenhang (aktive und ehemalige Aue) berücksichtigen. Dazu wurden gemischte Oberbodenproben (0-10 cm Mineralboden) an 44 Hartholzauwaldstandorten (2500m2) entlang 150 km der unteren Mittelelbe gesammelt und 18 Bodenprofile untersucht. Bodenparameter wie Korngrößenverteilung, pH-Wert, Gesamtkohlenstoff (TC), Gesamtstickstoff (TN), pflanzenverfügbarer Phosphor (Psol), Kationenaustauschkapazität (KAK) und Basensättigung (BS) wurden im Labor bestimmt. Die wichtigsten Ergebnisse zeigen, dass die Eindeichung einen starken Einfluss auf die Nährstoffverfügbarkeit in der Aue hatte. Die aktive Aue wies eine höhere Verfügbarkeit von Psol auf, was mit höheren pH-Werten im Boden und höchstwahrscheinlich mit der aktiven Sedimentation von Flusspartikeln und dem Eintrag löslicher Nährstoffe aus dem Überschwemmungswasser zusammenhing. Ehemalige Auenböden sind stark versauert und wiesen eine geringere Nährstoffverfügbarkeit auf. Dies ist auf das Fehlen von Überschwemmungen zurückzuführen, die die Akkumulation und Zersetzung von organischem Material und eine weitere Bodenentwicklung ermöglichen.
In der zweiten Studie untersuche ich die Saftflussgeschwindigkeit von fünf Eichen (Quercus robur) und fünf Ulmen (Ulmus laevis) unter hohem Verdunstungsbedarf und unterschiedlicher Bodenwasserverfügbarkeit (hoch und niedrig) an zwei aktiven Auenwaldstandorten (sandig und lehmig). In dieser Studie wurden während der Vegetationsperiode 2020 kontinuierlich Bodenwasserparameter wie der volumetrische Wassergehalt und die Wasserspannung in definierten Tiefen (bis zu 1,6 m unter Geländeoberkante) sowie mikrometeorologische Parameter und die Saftflussgeschwindigkeit der Bäume gemonitored. Die Saftflussgeschwindigkeit der Bäume wurde mit selbstgebauten Heat-ratio Geräten an drei Positionen pro Baum gemessen. Diese Daten wurden für die fünf Bäume pro Art und Standort gemittelt. Auf der Grundlage der gemessenen Werte des atmosphärischen Wassersättigungsdefizits und der Globalstrahlung wurde der potenzielle Saftstrom unter nicht wasserlimitierten Bedingungen mit Hilfe des Jarvis-Modells modelliert. Das Verhältnis zwischen modelliertem und gemessenem Saftfluss bei hoher und niedriger Wasserverfügbarkeit und für den sandigen und lehmigen Standort wurde anhand der gemessenen Bodenwasserspannung analysiert, um die Bedeutung des Bodenwassers für die Dynamik der Saftstromgeschwindigkeit zu bestimmen. Die Saftflussgeschwindigkeit von Ulmen war um bis zu 100 % höher als die der Eichen. Bei geringer Wasserverfügbarkeit, hohem Sättigungsdefizit und sandiger Textur verringerte Ulmus laevis die Saftflussgeschwindigkeit jedoch erheblich. Quercus robur wies geringere Saftflussgeschwindigkeiten sowie eine geringere Variabilität als Ulmus laevis auf und reagierte empfindlich auf das Bodensubstrat und die damit verbundene Wasserspeicherung im Boden. Die Saftflussgeschwindigkeit war bei sandiger Textur um 50 % niedriger als bei lehmiger Textur. Das Verhältnis zwischen gemessenem und modelliertem Saftfluss und dem Bodenwasserpotenzial zeigte, dass der gemessene Saftstrom auf dem sandigen Standort bei geringer Wasserverfügbarkeit vom potenziellen Saftfluss abweicht, was eine Verringerung der Saftflussgeschwindigkeit bei Ulmus laevis bedeutet. Mithilfe einer linearen Regression konnte ich zeigen, dass das Bodenwasserpotenzial einen Großteil der Variabilität der Saftflussgeschwindigkeit von Ulmus laevis erklären.
Beide Studien zeigen, wie wichtig es ist, die räumliche Komplexität der Bodeneigenschaften und -prozesse in Auen für Renaturierungsmaßnahmen zu berücksichtigen. Dies gilt insbesondere für die Wiederaufforstung mit Laubholzarten. Wir zeigen, dass die Nährstoffverteilung in den Auenböden von der Anbindung an die Flusshydrologie abhängt und dass die Standorte, die vom Fluss abgetrennt wurden, nicht den gleichen Nährstoffgehalt aufweisen wie diejenigen in der aktiven Aue. Die aktive Aue bietet in Bezug auf die Nährstoffverfügbarkeit ein höheres Potenzial für die Wiederherstellung von Hartholzauwäldern. In der aktiven Aue erklärt das Bodenwasserpotenzial die Schwankungen des Saftflusses in Trockenperioden und an sanddominierten Standorten. Was die Arten betrifft, so scheint Quercus robur toleranter gegenüber Trockenstress zu sein und sich besser an die Standortbedingungen anzupassen, indem die Saftflussgeschwindigkeit in Zeiten von Wasserstress verringert wird. Daher ist diese Art möglicherweise besser gerüstet, um Probleme wie Kavitation bei der erwarteten Zunahme von Dürreereignissen zu vermeiden
Einfluss der Bodenwasserverfügbarkeit und des lokalen Klimas in städtischen Gebieten auf die Wassernutzung etablierter Stieleichen (Quercus robur L.)
No full textFTAA: What's in It for the South?
No full textNot everyone in the Americas thinks that negotiating an FTAA is desirable. Some argue that the timing of the negotiations is being set by the agenda of the developed countries, particularly the US, and not that of the rest of the region. Others say that negotiating tariff reductions will do little to increase exports. The argument is that non-tariff barriers to trade must be part of the package, or the whole idea is a waste of time. These are just some of the opinions coming from the South. Interestingly, a number of these ideas are coming from Brazil, the hemisphere's most populous country after the US, and clearly a leader in the region. Presidential elections in Brazil took place in the fall of 2002 just prior to an FTAA Ministerial in Quito. In the lead up to the election, the FTAA positions of the opposition candidates, including the eventual winner, were much more protectionist than that of the outgoing government. If the protectionism carries through to official government policy, then the FTAA process will be much more difficult. However, this might just have been electoral talk. This paper will attempt to sort out truth from rhetoric.Brazil, non-tariff barriers, FTAA, South, International Relations/Trade,
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