Emerging synthesis themes from the study of social-ecological systems of a tropical city

The synthesis of the contributions in this special issue about the tropical city of San Juan has resulted in five themes. First, the city is subject to multiple vulnerabilities, but socioeconomic factors and education level affect the perception of citizens to those vulnerabilities, even in the face of imminent threat. Second, in light of the social-ecological conditions of the city, how its citizens and institutions deal with knowledge to respond to vulnerabilities becomes critical to the adaptive capacity of the city. Third, the relationship between socioeconomic factors and green cover, which in 2002 covered 42% of the city, is not what has been reported for other temperate zone cities. In San Juan, neighborhoods with households of high socioeconomic level were not necessarily associated with greater green cover. However, in adjacent neighborhoods within the densely populated zones of the city, households of high socioeconomic level did preserve green cover better than households in lower socioeconomic-level neighborhoods. Fourth, tropical conditions such as climate may explain some of the unique aspects of the social-ecological system of San Juan. The most obvious is the exuberance of tropical biota in the city that not only forms novel species assemblages but also provides many ecological services, including food production for up to 60% of the members of particular neighborhoods. Ecosystem resilience is particularly high in aquatic and terrestrial ecological systems in San Juan. Fifth, it appears that the emergence of novel systems in the city represent adaptive responses to the social end ecological conditions in the city. We conclude that the study of a tropical city provides contrast to the prevailing literature on temperate and boreal cities and expands the suite of behaviors of urban social-ecological systems, thus advancing the dialogue on the functioning of cities in light of environmental change.