PS 87-256
Land pattern dynamics of a tropical island in the context of urban sprawl and forest regrowth
Land use and land cover have been changing dramatically globally in the past decades. Urban population is expected to continued increase and urban areas are predicted to expand much faster than that of population, which has great impacts on the patterns and processes of adjacent natural ecosystems. As a heavily populated tropic island, Puerto Rico has experienced fast urbanization in 1970s and later urban sprawl after 1990s. While people migrated from rural area to urban, large amounts of agricultural land were abandoned and later transformed into pastures, shrubs, and secondary forests. This study aims to investigate the land pattern dynamics during the courses of urban sprawl and forest regrowth, and to explore the impacts of biophysical and socioeconomic factors on land pattern dynamics. We choose the existing land cover/use maps of 1977 – 2000 and the fragmentation indices of mean patch area, edge-to-area-ratio, edge density, and the largest patch index in our analysis. Then, we applied the spatial error models to quantify the roles of biophysical and socioeconomic factors in land fragmentation.
Results/Conclusions
Our results indicate that the number of urban patches increased from 99,960 to 108,198 during 1991 – 2000 with the 8% increase in total area. Although the largest urban patch increased, the decreased mean patch area and the increased edge-to-area ratio and edge density indicated slight urban fragmentation. The spatial pattern of urban fragmentation shows it is low inside the urban areas and tends to be high at the suburban areas. The results also suggested a general trend that a small number of large patches of urban may get more aggregated when close to the urban centers, however, small and moderate patches dominated in number and got more fragmented in this period. The peak urban fragmentation shifted from 7.3 km distance to urban in 1977 to 8.7 km in 1991 and to 10.4 km in 2000. This shift indicates significant urban sprawl toward far suburban and rural areas, with small patches developed progressively further away from the urban centers.