Differentiating and evaluating human-induced versus climate-induced impacts on urban vegetation in Denver, CO

Abstract

Changes in vegetation patterns within cities can have detrimental environmental consequences, including increased temperatures and exacerbated water and air pollution problems which threaten human health and preservation of environmental resources. Given expected growth in urban population, and in the context of climate change, understanding how city development effects urban green spaces is important in order to combat the negative effects decreased vegetation creates within cities. While the effects of traditional open space development on vegetation are well documented, the impacts of new city development practices (e.g. infill development) on vegetation have yet to be examined. As one of the country’s top ten fastest growing cities in the United States, Denver, Colorado provides a unique opportunity to study the effects of mandated infill development on vegetation patterns. Frequently cited as a “smart growth” alternative to traditional open space development, the current study investigates the effects of land cover change associated with infill development has on vegetation patterns across the City of Denver. Using the Normalized Difference Vegetation Index and a regression based statistical analysis, a methodology for identifying areas of change and the main drivers of those changes, is outlined. Results indicate that vegetation within Denver has significantly changed during the study period (1984-2016). Patterns within the city showed no significant correlation to precipitation drivers, suggesting anthropogenic factors may be the main driver of vegetation change within the city. Specifically, the majority of change is often linked to infill development with a majority of neighborhoods with significant decreased vegetation aligned to neighborhoods with significant amounts of infill. Study results highlight the importance in understanding anthropogenic impacts on vegetation and the danger in assuming new development practices provide all encompassing solution to traditional urban development. Results will also facilitate the City’s ability to properly develop and manage urban green spaces.