Hurricane Driven Changes in Vegetation Structure and Ecosystem Services in Tropical Urban Yards: a Study Case in San Juan, Puerto Rico

Abstract Urban forests are valuable spaces for species conservation, protection of local biodiversity and provision of ecosystem services. However, they are also vulnerable to the impact of extreme climate events like hurricanes. Understanding how urban forests are responding to hurricane disturbances is crucial to improve their design, management, and resilience. Here we analyzed pre-and post-hurricane surveys in 52 residential yards in San Juan to assess urban forests responses after Hurricanes Irma and Maria impacted Puerto Rico in 2017. We used these surveys to compare vegetation structure and composition (including species-specific mortality and damage rates) and to quantify changes in the ecosystem services provided by these yards. We found that hurricane disturbances significantly altered the structure but not the composition of yard vegetation. We detected a 27% reduction and 31% mortality of standing stems, and a significant reduction in plants health. Yard species composition was dominated by non-native species and this trend did not change with hurricane disturbance. Changes in vegetation structure translated into substantial reductions in ecosystem services. Food provision, an important service provided by a large proportion of yards before the hurricane, reported the highest reduction (41.9%) while carbon storage was the service that changed the least (9%). Our combined results emphasize the key role played by residential yards providing ecosystem services in tropical cities and call for further efforts to manage private and public urban forests in ways that may ensure their resilience to mitigate extreme climate events, provide multiple ecosystem services, and promote long-term urban sustainability.