Green infrastructure in New York City: top down and bottom up initiatives to improve environmental quality

European environmental policies so far have achieved important results at both Member State level and internationally. The United States has a different approach to Europe in this field: with a less pre-scriptive normative framework, several associations, organizations and public bodies work to improve envi-ronmental conditions in cities through the integration of green infrastructure. Vegetation can restore the envi-ronmental quality of dense urban areas by reducing the Urban Heat Island (UHI) effect, improving air quality and energy performance of buildings, and fostering biodiversity. The main objective of this research is to study initiatives and actions carried out and developed in New York City to help improve environmental and ecological conditions through the wider diffusion of green infrastructure. Top-down and bottom-up initiatives implemented in such dense city, considering the role played by Federal agencies, NYC Departments, and lo-cal communities, are analyzed.