Stephen P. Prisley

Cascading effects of feedbacks, disease, and climate change on alpine treeline dynamics

Whitebark pine (Pinus albicaulis) is important for tree island development in some alpine treeline ecosystems in western North America; therefore the effects of an exotic disease on whitebark pine may cascade to other species and affect how treeline responds to climate change. We developed an agent-based model to examine the interactive impacts of blister rust and climate change on treeline dynamics. Our model includes positive and negative feedback effects for population processes and infection in a neighborhood. We simulated a present-day-like whitebark pine treeline community in the northern U.S. Rocky Mountains under stable conditions, and then conditions of disease, climate amelioration, and their combination. The loss of pine to disease was only partly compensated by the effect of climate change, and resulted in less facilitation for other species-reversing the positive effects of climate amelioration. Spatially explicit simulation captured the cascading effects of neighborhood facilitation on treeline populations and patterns. Facilitation, particularly from whitebark pine, drives tree island development.Positive and negative feedbacks influence whitebark pine treeline dynamics.Climate amelioration reduces facilitation benefits, causing dispersed tree pattern.Blister rust disease-killed pine impacts all species, despite climate improvement.Treeline responded negatively with disease introduction, even when climate improved.

Spatial and Temporal Emergence Pattern of Lyme Disease in Virginia

The emergence of infectious diseases over the past several decades has highlighted the need to better understand epidemics and prepare for the spread of diseases into new areas. As these diseases expand their geographic range, cases are recorded at different geographic locations over time, making the analysis and prediction of this expansion complicated. In this study, we analyze spatial patterns of the disease using a statistical smoothing analysis based on areal (census tract level) count data of Lyme disease cases in Virginia from 1998 to 2011. We also use space and space-time scan statistics to reveal the presence of clusters in the spatial and spatiotemporal distribution of Lyme disease. Our results confirm and quantify the continued emergence of Lyme disease to the south and west in states along the eastern coast of the United States. The results also highlight areas where education and surveillance needs are highest.

The Geography of Grist, Flour, and Saw Mills: Indicators of Land-Use History in Virginia

The objective of this study was to use grist, flour, and saw mills as indicators of settlement and trace the relationship between the occurrence of mills and the physical geography in a county in the Appalachian Mountains. We verified the locations of 18 grist and flour mills and 26 saw mills that operated during the period of 1800 to 1950. Contrary to previous studies, which linked the location of mills to infertile soils, a majority of mills in our study area (100% of grist and flour mills and 77% of saw mills) were located on fertile, limestone-based soils. This difference may be attributed to the dependence on water as a power source. Thus, mills were located on rich soils adjacent to a river or creek. Present day land ownership patterns were influenced by the land use history of the area, with areas that had housed grist or flour mills remaining in private ownership, while areas that had been dominated by saw mills converting largely to federal ownership.

An Examination of the Demographic and Environmental Variables Correlated with Lyme Disease Emergence in Virginia

Lyme disease is the United States’ most significant vector-borne illness. Virginia, on the southern edge of the disease’s currently expanding range, has experienced an increase in Lyme disease both spatially and temporally, with steadily increasing rates over the past decade and disease spread from the northern to the southwestern part of the state. This study used a Geographic Information System and a spatial Poisson regression model to examine correlations between demographic and land cover variables, and human Lyme disease from 2006 to 2010 in Virginia. Analysis indicated that herbaceous land cover is positively correlated with Lyme disease incidence rates. Areas with greater interspersion between herbaceous and forested land were also positively correlated with incidence rates. In addition, income and age were positively correlated with incidence rates. Levels of development, interspersion of herbaceous and developed land, and population density were negatively correlated with incidence rates. Abundance of forest fragments less than 2 hectares in area was not significantly correlated. Our results support some findings of previous studies on ecological variables and Lyme disease in endemic areas, but other results have not been found in previous studies, highlighting the potential contribution of new variables as Lyme disease continues to emerge southward.

Understanding the relationships between American ginseng harvest and hardwood forests inventory and timber harvest to improve co-management of the forests of eastern United States

The roots of American ginseng have been harvested from the hardwood forests of the eastern United States, alongside timber, since the mid-1700s. Very little is known about this non-timber commodity relative to timber, although significant volumes of ginseng root have been harvested from the same forests along with timber. The harvest of ginseng correlated positively and significantly with hardwood forest area, hardwood growing stock volume, and timber removals. Also, it correlated with hardwood growing stock on public forestlands in the region. The annual wholesale value of American ginseng was estimated at approximately

Visualizing Linguistic Diversity Through Cartography and GIS

26.9 million compared to annual stumpage value of harvested hardwood timber of just over

The lay of the language: surveying the cartographic characteristics of language maps

1.27 billion. The volume of ginseng root harvested from natural forests represents substantial extraction of biomass, and the associated value represents substantial income for people living in an economically marginalized region. Co-management of eastern hardwood forests for timber and non-timber forest products could improve local economies and better conserve the biodiversity of these forests.

Drivers of Deforestation in the Lake Victoria Crescent, Uganda

While linguistic diversity is an integral component of cultural landscapes, the spatial depiction of languages fails to represent all community members. Language is difficult to map and established guidelines are lacking. The perception of power conveyed is arguably the most meaningful design issue in language mapping, as most language maps inaccurately show one language per place. This research examines the cartographic visualization of linguistic diversity, contributing to our understanding of the perception of power through cartographic decisions, with the application of a linguistic diversity index. The resulting maps serve as new figures for linguistic diversity lessons in educational contexts.

Developing a Topographic Model to Predict the Northern Hardwood Forest Type within Carolina Northern Flying Squirrel (Glaucomys sabrinus coloratus) Recovery Areas of the Southern Appalachians

Although visible in research in the 1980s and 1990s, works concerning language-mapping issues are recently rather absent. This is an unfortunate oversight given current GIS capability and its potential to tackle visualization issues that were previously simply acknowledged and accepted. Given that there are no established guidelines for language map construction, this work aims to renew attention to language mapping, beginning with a survey documenting the characteristics of published language maps. The survey components address the problematic aspects described in the literature, such as boundary representation and depicting linguistic diversity, and reveal their usage and frequency. The noted map characteristics include, but are not limited to: publication type, publication year, coverage area, language data or variable used, and symbology details. For consistent classification, we use a language-map symbology classification scheme found in previous research. In general, chorochromatic maps using polygonal map units dominate our survey. We also find further evidence supporting the problems outlined in language mapping literature with the widespread use of solid-line boundaries and depiction of only one language or feature per place. However, we also note some unique strategies used for handling uncertainty and linguistic plurality. Observations of tactics not captured by the existing 20-year-old typology lead us to create an updated language map symbology typology consistent with the trends observed in our survey. Overall, we document language mapping strategies in practice and provide direction for future research by highlighting the pros and cons of current cartographic approaches for depicting language.

A Review and Evaluation of Uncertainty Classification and the Error-Band Geometry Model

We examined key drivers of deforestation in the Lake Victoria Crescent, Uganda from 1989 to 2009 through a case study approach with a multiple-case design. Nineteen focus groups with local community members and forest officials, archival analysis, and field observation revealed both proximate causes and underlying drivers of deforestation. Proximate causes of deforestation included agricultural expansion into forests, unsustainable extraction of wood forest products, and clearing of forests for nonagricultural uses. Underlying drivers of these proximate causes included policy and institutional factors, economic factors, population growth, technological changes, and changes in culture—each resulting in alienation of local people from forest resources. Alienation of local people, defined as a psychological dispossession of responsibility for forest resources, is posited as the most important underlying driver of deforestation. We discuss the importance of the involvement of local people in the management and maintenance of forests in the Lake Victoria Crescent.