Plant Migrations Impact on Potential Vegetation and Carbon Redistribution in Northern North America from Climate Change

Forests have a prominent role in carbon storage and sequestration. Anthropogenic forcing has the potential to accelerate climate change and alter the distribution of forests. How forests redistribute spatially and temporally in response to climate change can alter their carbon sequestration potential. The driving question for this research was: How does plant migration from climate change impact vegetation distribution and carbon sequestration potential over continental scales? Large-scale simulation of the equilibrium response of vegetation and carbon from future climate change has shown relatively modest net gains in sequestration potential, but studies of the transient response has been limited to the sub-continent or landscape scale. The transient response depends on fine scale processes such as competition, disturbance, landscape characteristics, dispersal, and other factors, which makes it computational prohibitive at large domain sizes. To address this, this research used an advanced mechanistic model (Ecosystem Demography Model, ED) that is individually based, but pseudo-spatial, that reduces computational intensity while maintaining the fine scale processes that drive the transient response. First, the model was validated against remote sensing data for current plant functional type distribution in northern North America with a current climatology, and then a future climatology was used to predict the potential equilibrium redistribution of vegetation and carbon from future climate change. Next, to enable transient calculations, a method was developed to simulate the spatially explicit process of dispersal in pseudo-spatial modeling frameworks. Finally, the new dispersal sub-model was implemented in the mechanistic ecosystem model, and a model experimental design was designed and completed to estimate the transient response of vegetation and carbon to climate change. The potential equilibrium forest response to future climate change was found to be large, with large gross changes in distribution of plant functional types and comparatively smaller changes in net carbon sequestration potential for the region. However, the transient response was found to be on the order of centuries, and to depend strongly on disturbance rates and dispersal distances. Future work should explore the impact of species-specific disturbance and dispersal rates, landscape fragmentation, and other processes that influence migration rates and have been simulated at the sub-continent scale, but now at continental scales, and explore a range of alternative future climate scenarios as they continue to be developed.

Nurturing Change: Lilly Martin Spencer's Images of Children

This dissertation is the first full-length study to concentrate on American genre painter Lilly Martin Spencer's images of children, which constituted nearly one half of her saleable production during the height of her artistic career from 1848 to 1869. At this time, many young parents received advice regarding child rearing through books and other publications, having moved away from their families of origin in search of employment. These literatures, which gained in popularity from the 1830s onward, focused on spiritual, emotional, and disciplinary matters. My study considers four major themes from the period's writing on child nurture that changed over time, including depravity and innocence, parent/child bonding, standards of behavior and moral rectitude, and children's influence on adults. It demonstrates how Spencer's paintings, prints, and drawings featuring children supported and challenged these evolving ideologies, helping to shed light not only on the artist's reception of child-rearing advice, but also on its possible impact on her middle-class audience, to whom she closely catered. In four chapters, I investigate Spencer's images of sleeping children as visual equivalents of contemporary consolation literature during a time of high infant and child mortality rates; her paintings of parent/child interaction as promoting separation from mothers and emotional bonding with fathers; her prints of mischievous children as both considering changing ideals about children's behavior and comforting Anglo-American citizens afraid of what they saw as threatening minority groups; and her pictures with Civil War and Reconstruction subject matter as contending with the popular concept of the moral utility of children. By framing my interpretations of Spencer's output around key issues in the period's dynamic child-nurture literature, I advance new comprehensive readings of many of her most well-known paintings, including Domestic Happiness, Fi, Fo, Fum!, and The Pic Nic or the Fourth of July. I also consider work often overlooked by other art historians, but which received acclaim in Spencer's own time, including the lithographs of children made after her designs, and the allegorical painting Truth Unveiling Falsehood. Significantly, I provide the first in-depth analysis of a newly rediscovered Reconstruction-era painting, The Home of the Red, White, and Blue.