Land Use / Land Cover Changes have profound influences on the functions of coupled natural and human systems. Although deforestation has been a major topic in LULCC, reforestation can be significant in areas with economic shift. The tropical island Puerto Rico stood out as an example of reforestation because of the shift from agriculture to industry and services as a result of economic globalization after 1940s. With the abandonment of agriculture lands and subsequent reforestation, people migrated from rural to urban, and then to suburban, and sharply intensified urbanization and urban sprawl in the island. Urban sprawl often fragments the land cover, while reforestation may do the reverse. The magnitude of composite impacts of the two processes on natural ecosystems is largely unknown. Being important for flood mitigation, water purification, and biodiversity conservation for both ecological and economic values, tropical coastal wetlands are vulnerable to land use changes due to increased tourism, irrational construction, and water use. Climate change, such as drought and sea level rise, will further increase uncertainties to the future of tropical coastal wetlands. The key objective is to answer the scientific questions of: How do the land use changes (reforestation and urbanization), interacting with climate changes (drought and sea level rise), impact the vulnerability and the adaptation capacity of tropical wetlands spatiotemporally during the past 33 years in Puerto Rico? And what are the potential adaptive management plans for sustainable coastal wetlands in the context of climate change? Three hypotheses will be tested: 1) In spite of reforestation, island wide forests were fragmented by the urban sprawl, especially the low-density residential development. However, the coastal wetlands may aggregate due to the policy change, e.g., the implementation of The RAMSAR Convention on Wetlands 2) Land use and climate changes will make coastal wetlands more vulnerable by reducing water supply, decreasing water quality, and retreating shoreline due to sea level rise and 3) Adaptive scenarios of coastal wetlands management, such as restricted coastal development and water consumption, and wetlands restoration, will lead to more sustainable wetlands in the context of climate change.

We'll address the questions through: 1) synthesis of multi-temporal remote sensing images and existing land cover/use maps from 1977 to 2010, including Landsat TM and ETM, aerial photos, and AMSR-E (Advanced Microwave Scanning Radiometer-Earth Observing System) data for drought detection, together with demographic and socioeconomic data on population, construction, and commercial and residential water consumption 2) integrated modeling of watershed land use change and hydrologic dynamics to assess the vulnerability and adaptation capacity of tropical coastal wetlands through building different land use and climate scenarios and 3) collaborations with local Department of Natural and Environmental Resources and Planning Board on potential adaptive management of coastal wetlands for sustainability by socioeconomic survey and stakeholders involvement.

This proposal addresses both components of the solicitation. The land cover/land use changes in Puerto Rico, reforestation, urban sprawl, policy change, and their impacts on coastal wetlands in particular, for the last 33 years, will be synthesized. The vulnerability of coastal wetlands and possible adaptive management will be investigated by integrating models of Soil and Water Assessment Tool (SWAT) and The Conversion of Land Use and its Effects (CLUE-S), high-resolution remote sensing images (Landsat TM/ETM), AMSR-E data, Global Circulation Model outputs, and socioeconomic analysis. The proposed simulation and analysis of high-resolution and long-term satellites' images were highlighted in the NASA Science Mission and aligned with the strategic plan of US Climate Change Science Program.