Dissertation Abstract

Global change affects populations, communities, and ecosystems through individual level responses. Plants are the primary producers in most ecosystems, and woody plants in particular are important drivers of temperate systems. I addressed three axes of global change in my research- invasive species, land use/land cover (LULC), and climate- and how they relate to woody plant performance at multiple spatial scales. At the regional scale, I showed marked changes in LULC over a relatively short time period (1992-2006) in the northeastern US (New England), with a decline in forest cover, particularly core forest cover, and increased edge forest and scrub/shrubland in northern Maine. At the landscape scale, I clearly demonstrated higher woody invasive plant richness with more edge forest in the surrounding area, the converse pattern with core forest, and the relationships between forest fragmentation and socioeconomic, physical, and infrastructure factors. At the continental scale, I constructed species distribution models for four woody invasive plants with high prevalence in New England and occurrence elsewhere in the US. These models utilize novel approaches in Maximum Entropy modeling to combine native and invasive range distribution data into a single model prediction of habitat suitability for each species throughout the US. I used field experiment observations to show that woody invasive plants in New England leaf out earlier than ecologically analogous native plants and experience an extended growing season, but that phenological differences at the seedling stage do not necessarily translate to a performance advantage for the invaders. Finally, I developed phenological models that take advantage of daily weather data and used these models to forecast future flowering of Japanese cherries. Throughout most of my work, I used Bayesian methodology and developed novel statistical tools to address my research questions when current methods were inadequate. Through a combination of advanced modeling and careful interpretation, I provided forecasts of woody invasive species distributions, richness, leafing phenology, and cherry flowering phenology to aid in invasive species early detection and management in the US and planning culturally and economically important festivals abroad.