Residential expansion as a continental threat to US coastal ecosystems

Spatially extensive analysis of satellite, climate, and census data reveals human-environment interactions of regional or continental concern in the United States. A grid-based principal components analysis of Bureau of Census variables revealed two independent demographic phenomena, alpha-settlement reflecting traditional human settlement patterns and beta-settlement describing relative population growth correlated with recent construction in non-agricultural areas, notably in coastal, desert, and "recreational" counties and around expanding metropolitan areas. Regression tree analysis showed that beta-settlement was differentially associated with five distinct combinations of seasonality, summer heat or cool, intensity of agriculture, and extent of "barren" land. Beta-settlement was greatest in coastal and desert areas, and coincided with national concentrations of threatened and endangered species.