Six decades of urban green change in a neotropical city: a case study of Xalapa, Veracruz, Mexico

The process of expansion of human settlements commonly occurs without proper urban planning, which can directly affect green areas located within cities and adjacent areas. This study focuses on: (1) a spatiotemporal analysis to quantify the growth of the city of Xalapa (1950s to 2010s), (2) changes in woody vegetation cover within the boundaries of the city, and (3) land use and landscape changes and urban sprawl by decade from the 1980s to 2010s. To achieve this, we used digital images (i.e., ortho-photos, SPOT images), which were classified and integrated into a geographic information system. Based on the processed imagery, we delimited the urban polygon of the city, and quantified its woody vegetation cover changes and land use changes in areas surrounding the city for each decade of study. We found that over the past six decades, the city of Xalapa has grown in similar proportions per decade, mostly concentrated southward, fitting strongly and significantly to quadratic and linear growth patterns. Urban sprawl increased over the study period, Shannon’s relative entropy increasing from 0.58 to 0.73. Woody cover within the city occupied a similar proportion (19–29%) of total city area throughout the study period because of the addition of patches of woody vegetation from formerly outlying areas, despite infill urbanization replacing preexisting urban green areas. Land use change in the area surrounding the city went from a transition through different uses (e.g., woody vegetation to cropland to urban; 1980s–2000s), to a direct change from woody vegetation to urban use (2000s–2010s), and exhibited landscape fragmentation over the period of study. Our results show that an integrated combination of remotely-sensed data and landscape metrics can be used to monitor urban patterns and processes, and that the results obtained can be incorporated into urban planning and management.