Thèse-Paris. / Includes bibliographical references.

Agricultural practices play a crucial role when discussing sustainable development in the world. Organic farming is a possibility to increase the overall sustainability, because it balances the environmental, economic, social and productive spheres better than conventional farming. Thus, Germany strives to have 20 % of the agricultural land organically certified. However, with current organic farmland at 6.2 %, the goal is far from being reached and conversion rates are slowing down, whereas organic viticulture indicates more successful conversion rates. Thus, the objective of this study is to investigate which motives and barriers wine farmers in Pfalz and Rheinhessen, Germany, have to convert to organic farming. Furthermore, it is explored which role one of the world’s biggest retailers, Systembolaget, plays in the decision process to produce organically or not. The study was carried out reviewing literature and through a questionnaire and interviews with, in both cases, eight farmers from the regions of which four were certified organic and four were conventional farmers. Moreover, the five capitals framework, which attempts to assess livelihood strategies, was applied to analyze findings. Results indicate that most motives for organic farming identified in the literature could be placed in the financial, social and human capital, whereas the questionnaire and interviews found as many categories in the natural capital. Barriers to convert to organic farming were most frequent in the natural and physical capital both in the literature and the empirics. However, the findings suggest that a focus lies on the financial and human capital, in which the economic situation and the ideology of a farmer played a crucial role in the decision process. Systembolaget plays a supporting role in the conversion to organic farming, but it is not the driving factor in a conversion process. The findings indicate that policy could consider revising financial support schemes, address ideological barriers against organic farming and decide on the use of copper. Moreover, the organic label as marketing tool could be stressed and the influence of the private sector could be acknowledged in order to reach the organic farmland goal of Germany.

Thesis (doctoral)--Philosophisch-Theologische Hochschule Sankt Georgen, Frankfurt am Main, 2006.

Inaug.-Diss.--Munich. / Vita. Bibliography: l. vi-xx.

Dt. Hochsch. für Verwaltungswiss, Diss, 2006--Speyer.

In dieser Arbeit wurden die Veränderungen der agrarklimatologischen Bedingungen im Zuge des Klimawandels für ausgesuchte Sauerkirschanbauregionen in Europa und Nordamerika untersucht. Es wird auf veränderte Risiken (Spätfrost, Hitzewellen, Wassermangel) hingewiesen, die durch nachhaltige, praxisorientierte und ökonomisch vertretbare Anpassungsmaßnahmen (Überdachung, Frostschutz, Bewässerung, Anbausystem, Wahl der Sorte und Unterlage, etc.) begrenzt werden können. Der Klimawandel kann neben Risiken aber auch Chancen für den Sauerkirschanbau eröffnen. Höhere Temperaturen und eine längere Vegetationsperiode können regional differenziert zu günstigeren Anbaubedingungen führen. Ein besonderer Schwerpunkt wurde auf die Entwicklung phänologischer Modelle gelegt, mit denen Veränderungen im Entwicklungsrhythmus der Sauerkirschgehölze analysiert werden konnten. Dafür wurden acht Modelle zur Vorhersage des Blühbeginns und Blühendes entwickelt. Weitere phänologische Stadien konnten mit dem Modell von Zavalloni et al. (2006) berechnet werden. Die Untersuchungen haben ergeben, dass sich der Blühbeginn unter geänderten Klimabedingungen verfrüht, aber nur geringe Verkürzungen der Zeiträume zwischen den phänologischen Stadien zu erwarten sind. Zu den gefürchteten Witterungsschäden im Obstbau gehört Spätfrost, der zu hohen Ertragsverlusten führen kann. Im Zuge des Klimawandels können sich die Häufigkeit und Stärke der Fröste ändern. Die Frostwahrscheinlichkeit während der untersuchten Entwicklungsphasen von Sauerkischgehölzen könnte in diesem Jahrhundert in Rheinland-Pfalz und Eau Claire abnehmen, während sich die Verhältnisse in den anderen Anbaugebieten nur geringfügig ändern. In einem zweiten Schritt wurden die Ertragsverluste durch Frost bestimmt. Hierbei hat sich ergeben, dass die Frostschäden in den untersuchten Anbauregionen wahrscheinlich geringer werden. Allerdings differieren die Ergebnisse zwischen den Berechnungen mit beobachteten und modellierten Temperaturen oft stark. / This thesis investigates the changes in agro-climatic conditions for selected growing region in Europe and North America under current and future climate conditions. The overall aim of the study was to identify possible risks (spring frosts, heat waves, water shortages), which can be limited by sustainable, practically oriented and economically viable adaptation measures (hail- and frost-protection, irrigation, cultivation system, choice of variety and rootstock). Besides risks, climate change can provide new opportunities. Higher temperature levels and extended growing season lengths could regionally differentiated improve the growing conditions. Particular focus was given to developing phenological models, used to investigate shifts in spring phenology of sour cherry trees due to climate change. Therefore, eight models to predict the beginning and end of blossom were optimized and validated. Further phenological stages were calculated with the model by Zavalloni et al. (2006). The results show an earlier onset in the beginning of sour cherry blossom under future climate conditions, while the length of the period between the phenological stages only shortens slightly. Spring frosts are feared weather hazards in orchards which can cause substantial yield losses. The changing climate conditions could influence the frequency and strength of spring frosts. In the course of this century the spring frost probability is likely to decrease in Rhineland-Palatinate and Eau Claire, while only slight changes are expected in the other growing regions. In the second step, yield losses caused by spring frost were calculated. The frost damages on sour cherries in the investigated growing regions will probably decrease. However, the yield losses calculated with observed and modeled temperatures often differ strongly.