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In arid and semiarid environments, various natural and anthropogenic stressors have resulted in land cover change that has negatively impacted the ecological integrity of the landscape. Society, however, relies on many ecological processes and functions provided by the landscape to enhance its wellbeing. The direct and indirect benefits society receives from the landscape are collectively termed "ecosystem services." The overarching goal of this thesis was to examine how the landscape has changed and to analyze how these changes impact the ecosystem services supplied by the landscape. The Upper San Pedro watershed in southeastern Arizona and northern Sonora was used as a case study to link land cover change with an array of ecosystem services to understand the spatiotemporal dynamics of ecosystem service supply. To accomplish this, a multitemporal land cover dataset for the watershed was updated to extend the temporal coverage to 37 years across 5 land cover datasets. Indicators serving as proxy variables for a variety of ecosystem services were assessed for each land cover class. This linkage between land cover and ecosystem services enabled an analysis of the tradeoffs and synergies within the array of services each land cover class can provide. Combined with the multitemporal land cover dataset, the spatiotemporal dynamics of potential ecosystem service supply were analyzed across the watershed for a 37 year period. Rather than examining the impacts of land cover change on the biophysical aspects of the environment, this approach enables land managers and decision makers to explore the implications of a changing landscape on human wellbeing.

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Streams and groundwaters interact in distinctly different ways during flood versus base flow periods. Recent research in the Upper San Pedro River using isotopic and chemical data shows that (1) near-stream, or 'riparian,' groundwater recharged during high streamflow periods is a major contributor to streamflow for the rest of the year, and (2) the amount of riparian groundwater derived from this flood recharge can vary widely (10-90%) along the river. Riparian groundwater in gaining reaches is almost entirely basin groundwater, whereas losing reaches are dominated by prior streamflow.This description of streamflow gives rise to the questions of (1) how much flood recharge occurs at the river-scale, and (2) subsequently, what is the relative importance of flood recharge and basin groundwater in maintaining the hydrologic state of the riparian system. To address these questions, a coupled hydrologic-solute model was constructed for 45 km of the Upper San Pedro riparian system.

In this research, I describe the use of false rings to reconstruct local histories of seasonal drought in riparian ecosystems in semiarid regions. In tree-ring analysis, false rings are boundary-like features often formed as a response to drought within the growing season. Drought can be a common feature in hydrologic regimes of dryland rivers but in recent decades drought has been intensifying due to climate change and increasing water use by cities, agriculture and industry. Identifying when and where water availability has decreased along the river course is critical for understanding, and therefore managing, these generally endangered ecosystems. The higher density of trees compared to instrumental data make them ideal candidates for reconstructing site-specific drought patterns.The first part of this dissertation is an observational study conducted on the San Pedro River in southeastern Arizona during 2002. I used dendrometer data and local hydrological data to show that a period of negligible radial growth in cottonwood during the middle of the growing season coincided with a channel drying event. Tree-ring core samples confirmed that false-rings had formed in each of the instrumented trees. The second part of this dissertation is an experimental study designed to evaluate the effect of different levels of water stress on false-ring formation in cottonwood and willow. I showed that experimental decreases in water availability for periods as short as ten days were enough to induce false-ring formation in willow. Longer periods of reduced water availability were generally required to induce false-ring formation in cottonwood. In the final part of this dissertation, I reconstructed false-ring occurrence in Fremont cottonwoods at three sites along the San Pedro River. I infer from false-ring frequencies that the severity of summer drought has been increasing over the last four to six decades but that the drought severity varies along a hydrological gradient. Overall, the findings in this body of research confirm that false rings in riparian tree species can be used as indicators of seasonal drought and underscore the importance of identifying site-specific responses to reduced water availability along the riparian corridor.

Although Calderon formulates an eloquent refutation of racialist discourse against Muslims, my thesis concentrates on the issue that his play-writing reinforces the Cristocentric ideology on the need for conversion. In order to determine some of his influences and inspirations, I have reviewed the literature dealing with the Muslim subject in Spain from approximately the eleventh to the seventeenth centuries. Drawing on postcolonial hermeneutics and social psychology, I explored the way in which the image of the Muslim is constructed, wavering between an aggressive representation meant to promote rejection, and a narcisistic reflection fostering the appropriation through conversion. Both postures presuppose a distinction upon religious levels which has remained constant throughout the literature studied in this thesis. / By analysing some plays by Lope de Vega and Cervantes it became obvious that the fast reflects, with some exceptions, the dominant prejudices of his audience by presenting stereotyped characters of Muslim descent. Cervantes, on the other hand, provides a polyphony of voices which makes his plays peculiarly ambiguous for the inattentive reader. These, although exceptional in their humane view of the world, consistently maintained Muslims and Christians distinct and separate, albeit within relatively expansive categories. / Calderon uses a lopesque model of the bobo and conserves Cervantes' Weltanschauung. Nevertheless, his main aim can be directly traced to the counter-expulsion polemics of sixteenth- and seventeenth-century intellectuals, who attempted to find a solid foundation on which to base Christian indoctrination. Utilizing a typologic and providential version of history, Calderon attempts to convince his Christian public that they should improve themselves spiritually in order to convert Muslims, who in turn should pursue proselitist activities in their respective countries. The Muslims predisposed to conversion are therefore presented as clearly differentiated from the ones who aren't, associating the first with courtly ideals and the others with diabolic manifestations. A necessary element for successful conversion of people of distinct cultures is the elimination of the myth of "purity of blood," which Calderon defeats categorically. All in all, his insistence upon the absolute necessity of a sincere application of Christian doctrine anticipates the disaster which those who conceived the conversion program could not avoid.

The goal of this dissertation is to study the use, function and possibilities of the classical concept of imagination in the "comedias" of Pedro Calderon de la Barca (1600--1681). To begin, I explore the possibilities and limitations of imagination at three different levels: literary and aesthetic theory, psychological and gnoseological theory, and lastly that of cosmology. / Thus, after tracing the presence of the concept of imagination in all of Calderon's "comedias," I study its use in the dramatic discourse of Pinciano and Bances Candamo. Likewise, I discuss the ambiguities of this concept that Calderon himself openly explored in several of his plays. Later, I focus on an analysis and interpretation of imagination in La vida es sueno (Life is a Dream), particularly as it concerns the relationships between mankind and the universe, as well as the imaginative and dramatic possibilities of dreaming. / My next step deals with the relationship between theories of drama and imagination. This concentrates on: the way in which the author plays and manipulates the audience's affections, the creation of marvellous dramatic effects, and the relationship between imagination and performance. After, I analyze the interaction between physical senses and imagination, as well as the public's perception influenced by sophisticated staging techniques. Lastly, I discuss three crucial concepts, those of taste, public opinion and disillusionment ("desengano"), that are for Calderon obvious limitations to the possibilities of imagination.