The Urban Forest as a Regulator of the Urban Climate

Abstract

Climate change increases the frequency and intensity of extreme weather conditions. As a consequence, in the temperate zone and specifically in the Mediterranean basin, hot summer periods are more frequent and last longer. Living in big cities is less comfortable than countryside, especially in hot summer periods. Because of human infrastructure and urban structure in general (buildings, roads, cement, asphalt etc) urban climate is quite different and causes discomfort to people, especially during the summer. The major factor that can regulate the urban climate and reduce its’ negative effects on the people in a city is the urban vegetation. Today due to the problem of climate change the ecological role of urban greenery for controlling the temperature in the cities, is clearer than ever. According to this the main question is how can urban vegetation regulate the climate conditions and which is the appropriate management regime to achieve the benefits. The present work deals with the effects of the composition and structure of an urban forest on the Mediterranean urban climate, and specifically on air temperature, solar radiation (PAR), and UVB radiation. A wide range of measurement points was established in urban forests in the center of the city of Athens, Greece. The measurement points cover all the types of urban vegetation composition and structure and were carried out the summer period of 2011 and 2012. On each measurement point the vegetation and structure characteristics were calculated and estimated are: tree diameter (Dbh), total tree height, crown base height, crown length, crown diameter, crown ratio, crown density, species composition and canopy closure. The preliminary results showed significant differences of the PAR and UVB values between the canopy closure classes as well as the vegetation composition.