Determination of Alterations in Forest Condition Using Various Measures of Land Use Change along an Urban-Rural Gradient in the West Georgia Piedmont, USA

Our overall goal was to examine forest condition across different land use types through measurement of various biotic, abiotic, and anthropogenic variables. Thirty-six permanent 0.05-ha circular plots were established along an urban-rural gradient near Columbus, Ga, USA. In general, forest structure did not differ by land use type for the majority of variables measured. However, urban forests contained less total tree and hardwood species than developing or rural areas. Regarding forest condition, no differences were observed for pest or disease incidence by land use, but more mechanical injury (broken branches, wounds, etc.) was found in urban locales. Lichens were the most sensitive indicator of possible changes in forest condition. Lichen incidence, abundance, and species richness were the greatest in rural forests and the least in urban locations. These factors were related to several indicators of urbanization such as housing density and distance from roads. In this case study subtle, but significant changes in forest structure and condition may have resulted from alterations in land use patterns. 1. Introduction Urbanization is a leading cause of land transformation worldwide and is occurring rapidly in many regions of the United States as a result of an ever-expanding population base [1]. Urbanization describes a process whereby the portion of a population living in cities increases and land use is transformed into a more human-modified pattern of organization [2]. In sprawling metropolitan areas, development is outpacing population growth and Southern cities are among the most rapidly expanding areas of the country [3]. As a result, forested land in this region is being converted to human-modified urban uses at astonishing rates. As populations continue to rise, the conversion of land from rural to urban will only increase. This conversion of forested lands to highly-modified urban areas poses a major threat to the sustainability of Southern forests [4]. Having few topographic boundaries to curb sprawl, many areas of the Southern US are experiencing similar patterns of change. Due to these factors, understanding the mechanisms determining the vigor of those remaining forests is becoming more critical. As such, studies quantifying forest condition and relating these to changes in land use in surrounding areas are needed. Healthy forest ecosystems display a balance among tree growth, mortality, and regeneration, and maintain productivity and resiliency to environmental stress [5]. The study of urbanization effects on forest health (structure,