A GOLDEN AGE: FRENCH AND SPANISH CELLO MUSIC FROM SAINT-SAENS TO CASSADO

Motivated by both the delicacy of French music, such as La Mer by Claude Debussy, and the exotic atmosphere of Spanish music, such as Zigeunerweisen by Pablo Sarasate, I decided to investigate the characteristics of French and Spanish cello music from Camille Saint-Saens to Gaspar Cassad6. French cello music flourished from the end ofthel9th to the middle of the 20th century because of the innovation of many unprecedented techniques and experimentation with a variety of sonorities. The Spanish were heavily influenced by the French due to the geographical connection. Cello virtuosi like Auguste Tolbecque, August Franchomme, Pierre Fournier, and Paul Tortelier inspired composers of their day, creating a "golden age" of cello music. This dissertation consisted of three recitals in Gildenhom Recital Hall. The first recital was held on May lOth, 2007 at 5:30pm with pianist David Ballena. The second recital was held on October 14th, 2007 at 2pm with collaborators Minna Han, piano and Jenny Wu, violin. The third recital was held on March 301 2008 at 5:30 with pianist Naoko Takao. Here is the program of the recitals: The first recital: Gabriel Faure(1856-1924): Sonate pour Violoncello et Piano Op.109(1917) Gaspar Cassad6 (1897-1966): Suite per Violoncello Solo (1926) Claude Debussy (1862-1918): Sonate pour Violoncelle et Piano (1915) The second recital: Manuel de Falla (1876-1946): Melodia (1897), Romanza (1898) Camille Saint-Saens (1835-1921): Concerto for Cello and Orchestra No.1 in A minor Op.33 (1873) Maurice Ravel (1875-1973): Sonata for Violin and Cello (1920-22) The third recital: Pablo Casals (1876-1973): Song of the Birds (1925) Edouard Lalo (1823-1892): Concerto for Cello and Orchestra in D Minor (1877) Franscis Poulenc (1899-1963): Sonata for Cello and Piano Op.l43(1940-48)

THE DEVELOPMENT OF THE AMERICAN SOLO TUBA REPERTOIRE

A very good case can be made that no other instrument has experienced as dramatic an increase in artistic solo repertoire as the tuba in the past sixty years. Prior to 1954, the mainstays of the tuba repertoire were trite caricature pieces such as Solo Pomposo, Rocked in the Cradle of the Deep, Beelzebub, and Bombastoso. A few tubists, seeing the tremendous repertoire by great composers written for their brass brethren, took it upon themselves to raise the standard of original compositions for tuba. These pioneers and champions of the tuba accomplished a great deal in the mid to late twentieth century. They structured a professional organization to solidify their ranks, planned and performed in the first tuba recitals at Carnegie Hall, organized the First International Tuba Symposium-Workshop, indirectly created more prestigious positions for tuba specialists at major universities, and improved the quantity and quality of the solo tuba repertoire. This dissertation focuses on the development of the solo repertoire for tuba that happened in the United States because of the tremendous efforts of William Bell, Harvey Phillips, Roger Bobo, and R. Winston Morris. Because of their tireless work, tuba instrumentalists today enjoy a multitude of great solo works including traditional sonatas, concertos, and chamber music as well as cutting edge repertoire written in many genres and accompanied by a variety of mediums. This dissertation attempts to trace the development of the repertoire presenting the works of American composers in varying genres and musical styles from 1962 to present through three performed recitals.

FOLK ELEMENTS IN TWENTIETH-CENTURY HUNGARIAN MUSIC

At the beginning of the twentieth century, composers Béla Bartók and Zoltán Kodály collected thousands of folksongs from the rural regions of Hungary. In an effort to preserve a part of their culture that they feared would be lost, they not only transcribed and catalogued these folksongs, but also incorporated the folk traditions they encountered into their own compositional style. This dissertation deals with violin music written by Bartók, Kodály and their Hungarian contemporaries that have in common the use of rhythms, modes, melodies, figurations and playing techniques sourced in folk traditions. The use of the Hungarian folk idiom in classical music was not exclusive to the twentieth century. From the late eighteenth century until the first decades of the twentieth century, composers utilized aspects of a popular eighteenth-century form of Hungarian folk music called verbunkos. What makes the use of folk music unique in the twentieth century is that, thanks to the work of Bartók and Kodály, composers found inspiration in the more authentic “peasant music.” Unlike the popular, urban verbunkos music, peasant music was the product of the more secluded village-music tradition, largely untouched by the influences of city life. In addition to stimulating a new focus on peasant music, Bartók and Kodály fully assimilated the folk idiom into their compositional toolkits, creating a new style of folk-inspired art music that influenced a generation of Hungarian composers. The new style included characteristic elements of both peasant music and the verbunkos tradition, such as ancient modes and scales, accompanimental and melodic rhythmic patterns, ornamentation, and phrase structures sourced in folk song. To demonstrate the implementation of the folk idiom by twentieth-century Hungarian composers, three recital programs were given at the University of Maryland that included works by Béla Bartók, Sándor Veress, Leo Weiner, Zoltán Kodály, Ernő Dohnányi, Zoltán Székely and György Kurtág. The works can be divided into two main categories: settings or transcriptions of folk material (e.g. Bartók’s Hungarian Folksongs) and compositions using classical forms that include the Hungarian folk idiom (e.g. Bartók’s Contrasts). Recital collaborators include Li-Tan Hsu, Evelyn Elsing, Elizabeth Brown, Shelby Sender and Samantha Angelo.

CABARET: MIRROR OF SOCIETIES

The basic definition of a cabaret is a café that offers live entertainment performed by singers, musicians and dancers and serves food and drink. It is generally housed in small, intimate spaces. Starting in the middle of the nineteenth century, artists, composers and writers met at Parisian cafés and salons to share their works. The cabaret was a suitable place for social activities. Artists could meet, discuss their opinions, and share their art in a relaxed setting. Even though cabaret music was often based on popular idioms, social and political commentary coupled with satirical settings represented the true soul of the genre. This trend flourished in the late nineteenth and early twentieth centuries. The first cabaret in Paris, Le Chat Noir inspired the growth of similar places in major cities throughout Europe besides Paris. The three recitals that comprise this dissertation project were performed at University of Maryland venues: the Robert & Arlene Kogod Theatre on 11 May 2011, Ulrich Recital Hall on 4 December 2011, and Gildenhorn Recital Hall on 4 March 2012. The repertoire for the first recital included works by Erik Satie with mezzo-soprano Monica Soto-Gil, Friedrich Hollaender with soprano Gabrielle DeMers, William Bolcom with baritone Ethan Watermeier and mezzo-soprano Stepanie Sadownik, and Poulenc with baritone Andrew McLaughlin. André Previn‘s Tango Song and Dance with violinist Jennifer Kim served as the instrumental interlude. The second recital included songs by Friedrich Hollaender with mezzo-soprano Monica Soto-Gil, Hanns Eisler and Viktor Ullmann with mezzo-soprano Stephanie Sadownik, and Mischa Spoliansky with soprano CarrieAnne Winter. Victor Hollaender‘s Romance and Albumblatt were the instrumental interludes with violinist Jennifer Kim. The last recital featured works for piano and violin, the Graceful Ghost Rag by William Bolcom with violinist Jenny Wu, Four Souvenirs by Paul Schoenfield with violinist Jennifer Kim, Cabaret Songs by Benjamin Britten with soprano Linda Mabbs, and Souvenirs for piano four-hands by Samuel Barber with pianist Rita Sloan. The recitals were recorded on compact discs and are archived within the Digital Repository at the University of Maryland (DRUM).

RUSSIAN THREADS: THE PRESENCE OF RUSSIAN INFLUENCES IN TWENTIETH­ CENTURY ENGLISH CELLO MUSIC

A cursory glance at cello works by English composers during the twentieth- century yields an unexpected relationship to Russian musicians, history, culture, and religion. One must wonder how this connection or "Russian thread" came to be. When considering the working relationship of Benjamin Britten and Mstislav Rostropovich, the likelihood of such a connection is tangible, since their deeply personal friendship influenced Britten's music for cello. However, what is perhaps more interesting is the emergence of connections to Russia in the works of other English composers of the twentieth-century, featuring works from 1913-1996. This project was conceived after close study and analysis of Benjamin Britten's Third Suite for Solo Cello, Op. 87 (1971). Britten's inclusion of Russian folk tunes and an Orthodox Church hymn signaled the penetrating presence of Russian elements in his works. Britten's First Suite for Solo Cello, Op. 72, Third Suite for Cello, Op. 87, and Sonata for Piano and Cello in C, Op. 65 are presented in this project. Further exploration of works for cello by English composers unveiled similar connections to Russia. The Sonata for Cello and Piano of Frank Bridge is likened to Russian romanticism and the Cello Sonata of Sergei Rachmaninoff. William Walton's Cello Concerto was written for the Russian-American cellist Gregor Piatigorsky. Wake Up ...and die is John Tavener's deeply spiritual work, which is rooted in his Russian Orthodoxy. John Ireland, influenced by models of French and Russian Impressionism, contributed works colored with Russian folk influences, of which his Piano Trio No. 2 is an example. Finally, Arnold Bax traveled to Russia as a young man and his Folk Tale and Legend Sonata are imbued with the spirit of Russian folk music and architecture. This dissertation project is comprised of three recitals featuring English works for cello connected by a "Russian Thread." All events took place on the campus of University of Maryland, College Park: Recital #1 on December 4, 2011 in the Gildenhorn Recital Hall of the Clarice Smith Performing Arts Center, Recital #2 on February 11,2012, and Recital #3 on April 15, 2012, both in the Ulrich Recital Hall.

THE COMPLETE PRELUDES OF ALEXANDER SCRIABIN: THE EVOLUTION OF HIS REVOLUTIONARY COMPOSITIONAL STYLE

During the second half of the nineteenth century, a series of remarkable advances in musical composition emerged in the works of such innovative spirits as Franz Liszt, Hector Berlioz and Richard Wagner. Their pioneering works exerted an extraordinary impact on the music of the subsequent generation of composers--of disparate nationalities-who were active at the dawn of the 20th century: Including most notably Claude-Achille Debussy, Gustav Mahler, Richard Strauss, and Alexander Nikolayevich Scriabin. These important musical figures, each one leaving an indelible and formative imprint on late-nineteenth century Romantic style, together launched the modern era in music. Scriabin stands alone as a transcendental visionary: His music, initiated in the fashion of Chopin and Liszt, wanders through the realms of Debussy and Wagner, and, ultimately abandoning late Romantic tradition, unlocks the heretofore unforeseen power of atonality, bitonality, polyrhythms and key-signature free compositions. Arguably, Scriabin's compositions count among the most innovative, idiosyncratic and bewitching of all time. The development of Scriabin's groundbreaking compositional style is best understood by means of his piano works, which comprise the majority of his oeuvre. Beyond the larger works-his twelve sonatas, a concerto and a fantasy-Scriabin's piano explorations are also represented by miniature gems: The mazurkas, impromptus, waltzes, poems, a polonaise, etudes, nocturnes, morceaux and, in particular, the preludes. Scriabin's 90 preludes for piano, arranged in several opus numbers, richly exemplify the striking evolution of his ingenious music, his idiosyncratic philosophy and his provocative personality.

SELECTED ICONIC CHAMBER MUSIC WORKS WITH PIANO FROM THE NINETEENTH AND TWENTIETH CENTURIES

Chamber music repertoire featuring the piano blossomed from the mid-nineteenth through the early twentieth century. The quantity of works increased greatly during this time and the quality of these works reached the highest level. Among the many symbolic works that were composed were sonatas for a single string instrument with piano, piano trios, quartets: and quintets as well as two-piano works and four-hand duets. Being able to study and perform many of these iconic works before I graduated was one of the major goals I set for myself as a collaborative pianist. The abundance of repertoire has made it easy to choose works considered "iconic" for my dissertation's three recitals. Iconic is defined as "very famous or popular, especially being considered to represent particular opinions or a particular time" in the online Cambridge Advanced Leamer's Dictionary & Thesaurus © Cambridge University. The compositions featured in the recitals were composed from 1842 through 1941, including works by Schumann, Brahms, Faure, Rachmaninoff, Ravel, and Lutoslawski. Choosing the repertoire with my fellow performers in mind was an important part of this dissertation. In addition to trying to make balanced programs which include variety, working with different instruments and performers is one of the most fulfilling parts of the musical experience for me as a collaborative pianist. Joining me for the concerts were members of the Aeolus String Quartet (violinist Nicholas Tavani, violinist Rachel Shapiro, violist Greg Luce, and cellist Alan Richardson), pianist Hsiao-Ying Lin (a doctoral student from the Peabody Conservatory), and my colleagues from the Peabody Institute Preparatory Division (faculty violinist Dr. Christian Tremblay and cellist Alicia Ward), and Derek Smith, Associate Principal violist of the Annapolis Symphony Orchestras). The three recitals were performed in the Gildenhom and Ulrich Recital Halls at the University of Maryland, College Park, Maryland. They are recorded on CD and available on compact discs, which can be found in the Digital Repository at the University of Maryland (DRUM).

The Legacy of Oboist and Master Teacher, Robert Bloom

Robert Bloom (1908-1994) was legendary in the education and performance world. Often hailed as one of the last performers of the Golden Era of classical music and a favorite of conductors ranging from Stokowski to Stravinsky to Shaw, Bloom was an orchestral oboist and English hornist, oboe soloist, chamber musician, teacher (Eastman, Yale, Hartt, Manhattan School of Music, Juilliard and Philadelphia's University of the Arts), composer, conductor, editor of masterworks of the 18th century, and, as a founding member of the Bach Aria group, a seminal influence in the post-WWII revival of Baroque music in America. In The Robert Bloom Collection and the Art of Robert Bloom CD and video archives, we see what his musical ideals were in 1)18th-century performance practices, 2) writing new music for the instrument and commissioning new works, and 3) and transcribing music for the oboe and English horn. As an oboist, I believe it is important that Bloom's teachings, historical performance practices and ideas for expanding repertoire are propagated. Therefore, the works chosen for this dissertation illustrated this legacy. My recitals included 1) some of Bloom's published 18th-century baroque elaborations (his term for ornamentation), as well Baroque works which I have elaborated, 2) works written by him and by other oboists/composers (Labate, Roseman) as well as a flute/oboe duo that I commissioned by Dr. Marcus Maroney and 3) transcriptions by both Bloom and myself (Bach, Donizetti, Mendelssohn, Mozart, Handel, Schumann and Telemann). In these three dissertation recitals, I hope to have illustrated some of Robert Bloom's lasting contributions and impact on the oboe world, and to have demonstrated the potential for carrying forward this legacy by studying his teaching and emulating his example.

Dance Based Music on Piano

According to the Merriam-Webster dictionary, the definition of dance is “to move your body in a way that goes with the rhythm and style of music that is being played.” As you can see in that definition, these two important ways of expressing human feelings, music and dance, are very closely related. Countless pieces of music have been composed for dance, and are still being composed. It is impossible and useless to count how many kinds of dances exist in the world. Different kinds of dances have been developed according to their purposes, cultures, rhythm and tempo. For this reason, the field of dance-related music necessarily expanded significantly. A great deal of dance music has been written for orchestras, small ensembles, or vocals. Along with them, keyboard music also has a huge repertoire of dance pieces. For example, one of the most famous form in Baroque period was suites. Suites usually include 5 or more dance movements in the same key, such as Minuet, Allemende, Courant, Sarabande, Gigue, Bourree, Gavotte, Passepied, and so on. Nationalistic dances like waltz, polonaise, mazurka, and tarantella, were wonderful sources for composers like Chopin, Brahms, and Tchaikovsky. Dance-based movements were used for Mozart and Beethoven’s piano sonatas, chamber works and concertos. Composers have routinely traveled around the world to collect folk and dance tunes from places they visit. For example, Bartok and Balakirev's pieces that are based on folk dances from where they had traveled became famous and are still thought to be valuable for studying and performing today. For these reasons, it is clear that dance-related music is a very important part of keyboard music. In three dissertation recitals, to expand my performing repertoire and to understand dance-related music deeper, I tried to explore many different styles of dances, and compare interpretations between composers. This program note contains information about each pieces’ composers, related dances, and backgrounds. I hope this will be helpful for a future performer who’s seeking an effective dance based keyboard piece.

Promedio bayesiano de modelos para la predicción del consumo máximo de oxígeno en deportistas con datos de no-ejercicio

Históricamente, los modelos de no-ejercicio para predecir el consumo máximo de oxígeno (VO2max) han sido construidos mediante regresión lineal frecuentista, usando técnicas estándar de selección de modelos. Sin embargo, existe incertidumbre acerca de la estructura estadística en el proceso de selección del modelo. En este estudio se propuso construir un modelo de no-ejercicio para predecir el VO2max en deportistas orientados al rendimiento, considerando la incertidumbre de modelo a través del Promedio Bayesiano de Modelos (BMA). Un objetivo adicional fue comparar la performance predictiva del BMA con las de los modelos derivados de varias técnicas frecuentistas usuales de selección de variables. Con tal fin, se implementó un submuestreo aleatorio estratificado repetido. Los datos incluyeron observaciones de la variable respuesta (en L·min-1), así como registros de Género, Deporte, Edad, Peso, Talla e Índice de masa corporal (BMI) (Edad = 22.1 ± 4.9 años, media ± SD; n = 272). Se propuso una clasificación de deportes con el objetivo de incluirla dentro del proceso de construcción del modelo: Combate, Juego, Resistencia 1 y Resistencia 2. El enfoque BMA se implementó en base a dos métodos: Occam's window y Composición de Modelo mediante el método de Monte Carlo con Cadenas de Markov (MC²). Se observaron discrepancias en la selección de variables entre los procedimientos frecuentistas. Ambos métodos de BMA produjeron resultados muy similares. Los modelos que incluyeron Género y las variables dummies para Resistencia 1 y Resistencia 2 acumularon virtualmente toda la probabilidad de modelo a posteriori. El Peso fue el predictor continuo con la más alta probabilidad de inclusión a posteriori (menor a 0.8). Las combinaciones de variables que involucraron predictores con un alto nivel de multicolinealidad fueron desacreditadas. Los modelos con sustancial contribución para el BMA presentaron un ajuste apreciable (R² ajustado menor a 0.8). Entre los modelos seleccionados por estrategias frecuentistas, el obtenido mediante el método de regresión por pasos (Stepwise regression method) con alfa igual a 0.05 fue el más respaldado por los datos, en términos de probabilidad de modelo a posteriori. En concordancia con la literatura, el BMA tuvo mejor performance predictiva de los datos fuera de la muestra que los modelos seleccionados por técnicas frecuentistas, medida por la cobertura del intervalo de predicción de 90 por ciento. La clasificación de deportes reveló resultados consistentes.

Variación fenotípica del comportamiento vegetativo, reproductivo y germinativo de poblaciones de Paspalum dilatatum Poir

Paspalum dilatatum Poir.(pasto miel.), es una gramínea forrajera nativa de producción estivo-otonal, que se halla en la pampa deprimida integrando comunidades de loma, media loma o bajo, sujetas periodicamente a inundaciones y sequias, o pastoreo continuo. Con el objetivo de analizar los componentes de la variación se realizaron estudios recíprocos, simulando ambientes de inundación, capacidad de campo (capacidad de campo) y sequía en semillas y plantas provenientes de poblaciones de loma (A) y bajo (C). Se analizó el comportamiento germinativo de las semillas cosechadas de los mencionados tratamientos, con y sin pretratamiento con agua a 4ºC e igual concentración salina que el agua de inundación de la región. Se hallaron diferencias significativas, al analizar todos los factores se destaca el comportamiento contrastante entre poblaciones cuando las semillas fueron pretratadas y procedieron de ambientes con sequía. Adicionalmente se halló que el pretratamiento permitió observar diferencias entre las poblaciones que sin el pretratamiento no se manifestaron. Se evaluaron las diferencias en crecimiento vegetativo y reproductivo para cada una de las poblaciones en los tratamientos inundación, capacidad de campo y sequía. En esfuerzo reproductivo, se observa que las plantas de loma, en el tratamiento de capacidad de campo producen la mayor cantidad de semillas/unidad de biomasa total producida, respecto de las plantas provenientes de la población de bajo. Estas, no presentan diferenciación en cuanto a los ambientes inundación y capacidad de campo. Las diferencias halladas en comportamiento vegetativo, tanto para la biomasa aérea como para la relación T/R, entre otros, indicarian la existencia de ecotipos de altos y ecotipos de bajos de la misma especie resultado de presiones selectivas diferentes en altos y bajos.

Estimación remota del área de planta en un bosque seco : validación de un sistema autónomo de captura y almacenamiento de datos

El índice de área foliar es clave en el control de los procesos de los ecosistemas y como tal se busca estimarlo cada vez con mayor precisión y frecuencia para estudios locales, regionales y globales. Los métodos han evolucionado desde la medición directa hasta la utilización de instrumentos ópticos, logrando reducir los esfuerzos y los costos y permitiendo ampliar la frecuencia, la cobertura geográfica y la variedad de ambientes en la estimación de la variable. Una herramienta de estimación es el sistema PASTiS 57, desarrollado en el INRA, que permite registrar la transmitancia de la radiación en la porción del azul del espectro automáticamente cada 1 minuto, derivando de ella el índice de área de planta (PAI). El sistema se ha probado con éxito en bosques boreales y áreas agrícolas, pero no ha sido validado en bosques secos o en áreas semiáridas. El objetivo de este trabajo fue estimar la evolución de PAI con sensores autónomos en tres sitios en un bosque seco en la provincia de San Luis bajo diferentes coberturas a lo largo de un año y evaluar su desempeño en relación a estimaciones realizadas con fotografías hemisféricas, ampliamente validadas para la obtención de PAI. El PAI obtenido mostró una evolución temporal similar al estimado con el método convencional, presentándose hasta el momento como la única herramienta para realizar un monitoreo continuo de esta variable en tierra, en una escala de detalle mayor que la de los sensores remotos satelitales, y requiriendo un menor esfuerzo de muestreo que el habitual con fotografías hemisféricas y otros sensores ópticos manuales.

Calidad de suelos y secuestro de carbono bajo distintos usos en hapludoles mono y poligenéticos de la pampa arenosa

El paisaje de la pampa arenosa fue construido sobre antiguas geoformas medanosas que determinaron la presencia de suelos muy disímiles coexistiendo a nivel de lote. En los últimos años, fue aumentando la superficie destinada al cultivo de granos a expensas de las pasturas. Los objetivos generales fueron evaluar el secuestro de carbono y la calidad de suelos mono y poligenéticos bajo distintos usos, considerando las propiedades más sensibles a modo de lograr un conjunto mínimo para un monitoreo más simple de los cambios en la calidad de los suelos de la región. Se muestrearon dos situaciones de uso; agricultura continua (AGRICOLA) y en rotación con pasturas (MIXTO), evaluadas en dos subgrupos taxonómicos; Hapludoles énticos (HE) y Hapludoles thapto árgicos (HTA), considerándose dos profundidades 0-10 cm y 10-20 cm. De cada situación (USO SUELO) se realizaron tres repeticiones. Las propiedades determinadas fueron: carbono orgánico total (COT), carbono orgánico particulado (COP), carbono orgánico asociado a la fracción mineral (COM), densidad aparente (DAP), resistencia a la penetración (RP), infiltración básica (IB), índice de estructura (IE) y estabilidad de agregados (PromE), distinguiendo mediante diferentes pretratamientos (Le Bissonnais, 1996) entre mecanismos de desagregación (HRap, HLen, Heta). Los mejores indicadores de calidad dinámica para conformar un conjunto mínimo de aplicación en la región fueron HRap, COP y DAP. Estos indicadores mostraron que los suelos en rotación presentaron una condición de calidad superior. Las propiedades de mayor divergencia entre tipos de suelos fueron las relacionadas con sus diferencias texturales: COM, DAP, RP, IE y Heta. El método de Le Bissonnais presentó gran habilidad para detectar los mecanismos de desagregación que más condicionan la estabilidad de los suelos bajo las situaciones de uso evaluadas. Si bien se percibieron cambios en la distribución vertical del COT entre usos y suelos, la capacidad de secuestro de carbono hasta el metro de profundidad fue similar.

Efectos de la herbivoría doméstica sobre el enriquecimiento leñoso de las sabanas abiertas del centro sur de la Provincia de Corrientes

Los ecosistemas de sabanas se caracterizan por la co - dominancia de un estrato herbáceo continuo y otro leñoso discontinuo. En la región Centro - sur de la Provincia de Corrientes, la creciente lignificación de las sabanas se ha convertido en el principal obstáculo para el desarrollo de la actividad ganadera. En este trabajo examiné algunos factores que podrían controlar el establecimiento de plantas leñosas, especialmente evalué : 1- El efecto de la competencia de la vegetación herbácea sobre el reclutamiento de Acacia caven en diferentes parches de vegetación (pastos cortos y matas de pastos altos). 2- El papel de la vegetación residente sobre la susceptibilidad o resistencia a la herbivoría doméstica de Acacia caven. Una planta de A. caven y cuatro semillas, fueron asignadas a cada tipo de parche y tratamiento (control: sin corte de la vegetación, corte cada 40 y 20 días, y remoción total de la biomasa aérea y subterránea), el experimento se llevó a cabo durante dos estaciones de crecimiento (2007-2008,2008-2009). En ausencia de pastoreo, la remoción total de la vegetación herbácea aumentó la emergencia y supervivencia de Acacia caven mientras que el pastoreo doméstico tuvo el efecto contrario. A escala de micrositio, existió una tendencia a resistencia por asociación cuando las leñosas se reclutaron en la vecindad de una mata de pastos altos mientras que existió una tendencia a susceptibilidad por asociación en la vecindad de los pastos cortos. Los patrones naturales de reclutamiento de leñosas mostraron la misma tendencia. Se concluye que el pastoreo doméstico manejando la carga animal de manera que no lleve al deterioro del recurso forrajero sería una herramienta apropiada para disminuir las probabilidades de reclutamiento de las plantas leñosas jóvenes. Contrariamente, el sobrepastoreo al eliminar la competencia de la vegetación favorecería al establecimiento exitoso de leñosas.

Intercambios de masa y energía entre la vegetación y la capa límite atmosférica en dos ecosistemas de Argentina

Dentro del contexto del Cambio Global ha surgido el interés en conocer y entender la dinámica de los ecosistemas. La técnica Eddy Covariance (EC) es utilizada a nivel global para el registro continuo de los intercambios turbulentos de masa y energía en una diversidad de ecosistemas, con sensores montados en torres micrometeorológicas y en plataformas móviles. Así mismo, el empleo de modelos atmosféricos de mesoescala suma un aporte a la compresión de los procesos de intercambio suelo-atmósfera dentro de la Capa Límite Atmosférica. Lo enunciado anteriormente motivó la elaboración de la presente tesis en la cual se planteó caracterizar los intercambios turbulentos, estudiando su variabilidad sobre un bosque seco nativo y uno implantado en Argentina y evaluar el desempeño del modelo BRAMS-4.2 en alta resolución en reproducir estos intercambios. A partir de los valores observados, se encontró que la concentración media diaria y los flujos de CO2 presentaron un marcado ciclo diurno. El valor medio de las concentraciones en el bosque implantado fue igual a 736.2 más o menos 42.4 mg/m3 y en el bosque nativo igual a 641.9 más o menos 22.4 mg/m3. Los flujos de CO2 presentaron una amplitud media mayor en verano igual a 1.42 mg/m2s (0.27 mg/m2s) en el bosque implantado (bosque nativo). Los flujos de calor latente registrados en el bosque implantado fueron mayores a los registrados en el bosque nativo. La implementación del sistema de sensores instalados a bordo del avión Sky Arrow 650 ERA permitió realizar mediciones en los primeros metros de la atmósfera. El modelo BRAMS-4.2 supo reproducir razonablemente bien distintas variables meteorológicas así como también los flujos de masa y energía. Los resultados obtenidos en esta tesis son un aporte para ampliar el conocimiento sobre los intercambios turbulentos entre la vegetación y las capas bajas de la atmósfera en distintos ecosistemas de Argentina.