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Management actions to mitigate the impacts of invasive plant species require knowledge of the mechanisms influencing invasion success and anticipating interactions with various control options. To meet this need, I examined the impacts of the invasive plant Rubus niveus on the native communities of the Scalesia forest of Santa Cruz Island; its competitive abilities compared to some native, woody, species; and, factors affecting the invasion process. This knowledge was then used to evaluate and understand the failure of a five year eradication attempt of R. niveus on Santiago Island. Increasing densities of R. niveus had a negative effect on plant diversity and abundance also resulting in changes of forest structure. Experimental plots were used to elucidate mechanisms of how it displaced native species. Rubus niveus showed a faster growth rate and biomass production than native woody species; it also had a vastly larger seed bank. Increasing sunlight positively affected the growth, biomass production and reproduction of adult plants whereas germination was optimal at intermediate light conditions. Conversely, water stress affected mainly the performance of R. niveus whereas native species were more resilient. Although increasing native canopy cover negatively affected density of R. niveus, it still survived under low light conditions. The implication is that R. niveus rapidly invades after individual tree-falls or stand dieback but also is capable of invading undisturbed forest. After five years of intensive management of R. niveus in Santiago Island eradication seems unlikely. The invasion area continues to expand because: a failure to find all plants before they fruit, bird dispersal over long distance and the ability to colonize undisturbed areas and outcompete native vegetation. Furthermore, management actions have altered ecosystem processes. A more strategic paradigm in needed for R. niveus in Galapagos.

[Abstract] The first part of the article refers to the theoretical framework of "migratory cir.. culation". It explains the conceptual elements that constitute the "migratory circu.. lation", understood as a process started within the cultural and intersubjective ditnension of a comunity, where its members receive and assimilate the "l11.eaning" (Gel11.einter Sinn) of labor migration to the United States. There follows the deci.. sion to emigrate and the process of moving froln one habitual residence to another in the United States. Migration is seen as a mean of finding a job in another country. The process of moving away and getting a job can be observed and quan.. tified, giving rise to the investigations and results, described in the second part of the article. Some graphics, maps and pictures are included to validate the theoreti.. cal fral11.eWork of "migratory circulation" [Resumen] La primera parte se refiere a una explicación del marco teórico de la "circulari... dad migratoria". La segunda parte se dedica a la validación elupírica de ese 111arco teórico. En la primera parte se explican los elementos conceptuales que conforman la circularidad luigratoria, vista como un proceso que empieza en la din1ensión cul... tural e intersubjetiva de una comunidad donde sus miembros reciben y procesan el "sentido" (Gemeinter Sinn) de la migración laboral a Estados Unidos. De ahí surge la decisión de emigrar y la conducta de desplazamiento desde la residencia habitual hasta algún lugar de Estados Unidos. El desplazamiento es visto como un medio para lograr el fitl de obtener trabajo en el otro país. Ambos, el desplazamiento y la obtención de trabajo implican conductas observables y medibles. Esto es lo que da lugar a las investigaciones cuyos resultados se presentan en la segunda parte. La selección de gráficas, mapas y cuadros, responde a un objetivo de validación del l11.arCO teórico de la "cirularidad migratoria".