Influence of Soil Biogeochemical Properties on the Invasiveness of Old World Climbing Fern (Lygodium microphyllum)

The state of Florida has one of the most severe exotic species invasion problems in the United States, but little is known about their influence on soil biogeochemistry. My dissertation research includes a cross-continental field study in Australia, Florida, and greenhouse and growth chamber experiments, focused on the soil-plant interactions of one of the most problematic weeds introduced in south Florida, Lygodium microphyllum (Old World climbing fern). Analysis of field samples from the ferns introduced and their native range indicate that L microphyllum is highly dependent on arbuscular mycorrhizal fungi (AMF) for phosphorus uptake and biomass accumulation. Relationship with AMF is stronger in relatively dry conditions, which are commonly found in some Florida sites, compared to more common wet sites where the fern is found in its native Australia. In the field, L. microphyllum is found to thrive in a wide range of soil pH, texture, and nutrient conditions, with strongly acidic soils in Australia and slightly acidic soils in Florida. Soils with pH 5.5 - 6.5 provide the most optimal growth conditions for L. microphyllum, and the growth declines significantly at soil pH 8.0, indicating that further reduction could happen in more alkaline soils. Comparison of invaded and uninvaded soil characteristics demonstrates that L. microphyllum can change the belowground soil environment, with more conspicuous impact on nutrient-poor sandy soils, to its own benefit by enhancing the soil nutrient status. Additionally, the nitrogen concentration in the leaves, which has a significant influence in the relative growth rate and photosynthesis, was significantly higher in Florida plants compared to Australian plants. Given that L. microphyllum allocates up to 40% of the total biomass to rhizomes, which aid in rapid regeneration after burning, cutting or chemical spray, hence management techniques targeting the rhizomes look promising. Over all, my results reveal for the first time that soil pH, texture, and AMF are major factors facilitating the invasive success of L. mcirophyllum. Finally, herbicide treatments targeting rhizomes will most likely become the widely used technique to control invasiveness of L. microphyllum in the future. However, a complete understanding of the soil ecosystem is necessary before adding any chemicals to the soil to achieve a successful long-term invasive species management strategy.

Relectura del discurso novomundista de Alejo Carpentier y Abel Posse en el contexto de la nueva novela historica

The purpose of this dissertation was to analyze the narrative works of Alejo Carpentier and Abel Posse within the context of the new Latin American historical novel that revises the Old World-New World Encounter. Focusing on El arpa y la sombra and Los perros del paraíso , the dissertation studied the particular manner in which Latin American novelists, and particularly Alejo Carpentier and Abel Posse, approach and question traditional historiography. The research also compared different novels to identify various trends within the new historical novel that rewrites the foundational period of Latin American literature. ^ This study considered the theories of the new historical novel as proposed by critics such as Seymour Menton, Fernando de Aínsa, Linda Hutcheon, and Brian MacHale. The new novel was examined within the frameworks of postmodern literary and historiographic theories. The study also contemplated the philosophical views that have influenced postmodern thought, and, especially, the ideas of Nietzsche, Heidegger, Lyotard, Harbermas, and Foucault. ^ Research showed two major trends within the new Latin American historical novel. In the case of the first trend, initiated by Alejo Carpentier in 1949 with El reino de este mundo, the novelist's approach is founded on historicism and factual rigor. The second trend, initiated by Reinaldo Arenas with El mundo alucinante in 1969, is marked by irreverence, parody, irony, and carnavalization. Characterized by intertextuality, dialogism, and anachronism, novels such as Carpentier's El arpa y la sombra and Posse's Los perros del paraíso, undermine the values and beliefs instituted by the traditional historiographic paradigm and the discourse of power. ^

Relectura del discurso novomundista de Alejo Carpentier y Abel Posse en el contexto de la nueva novela histórica

The purpose of this dissertation was to analyze the narrative works of Alejo Carpentier and Abel Posse within the context of the new Latin American historical novel that revises the Old World-New World Encounter. Focusing on El arpa y la sombra and Los perros del paraíso, the dissertation studied the particular manner in which Latin American novelists, and particularly Alejo Carpentier and Abel Posse, approach and question traditional historiography. The research also compared different novels to identify various trends within the new historical novel that rewrites the foundational period of Latin American literature. This study considered the theories of the new historical novel as proposed by critics such as Seymour Menton, Fernando de Aínsa, Linda Hutcheon, and Brian MacHale. The new novel was examined within the frameworks of postmodern literary and historiographic theories. The study also contemplated the philosophical views that have influenced postmodern thought, and, especially, the ideas of Nietzsche, Heidegger, Lyotard, Harbermas, and Foucault. Research showed two major trends within the new Latin American historical novel. In the case of the first trend, initiated by Alejo Carpentier in 1949 with El reino de este mundo, the novelist’s approach is founded on historicism and factual rigor. The second trend, initiated by Reinaldo Arenas with El mundo alucinante in 1969, is marked by irreverence, parody, irony, and carnavalization. Characterized by intertextuality, dialogism, and anachronism, novels such as Carpentier´s El arpa y la sombra and Posse´s Los perros del paraíso, undermine the values and beliefs instituted by the traditional historiographic paradigm and the discourse of power.

A conceptual ecological model to facilitate understanding the role of invasive species in large-scale ecosystem restoration

We developed a conceptual ecological model (CEM) for invasive species to help understand the role invasive exotics have in ecosystem ecology and their impacts on restoration activities. Our model, which can be applied to any invasive species, grew from the eco-regional conceptual models developed for Everglades restoration. These models identify ecological drivers, stressors, effects and attributes; we integrated the unique aspects of exotic species invasions and effects into this conceptual hierarchy. We used the model to help identify important aspects of invasion in the development of an invasive exotic plant ecological indicator, which is described a companion paper in this special issue journal. A key aspect of the CEM is that it is a general ecological model that can be tailored to specific cases and species, as the details of any invasion are unique to that invasive species. Our model encompasses the temporal and spatial changes that characterize invasion, identifying the general conditions that allow a species to become invasive in a de novo environment; it then enumerates the possible effects exotic species may have collectively and individually at varying scales and for different ecosystem properties, once a species becomes invasive. The model provides suites of characteristics and processes, as well as hypothesized causal relationships to consider when thinking about the effects or potential effects of an invasive exotic and how restoration efforts will affect these characteristics and processes. In order to illustrate how to use the model as a blueprint for applying a similar approach to other invasive species and ecosystems, we give two examples of using this conceptual model to evaluate the status of two south Florida invasive exotic plant species (melaleuca and Old World climbing fern) and consider potential impacts of these invasive species on restoration.