Investigating and analysing the summer season soil temperature conditions on the extensive green roofs in Oslo, Norway

Abstract

Recently, green roofs have been investigated in-creasingly to improve the quality of municipal environment particularly to reduce the urban heat island effect and storm water runoff. Soil temperature is one of the most fundamental factors influencing these topics. This should also be considered as an important element for plant distribution and community composition on extensive green roofs. The aim of this study is to investigate summer season soil temperature conditions on extensive green roofs in Oslo. The study has been performed on 37 plots on 17 extensive green roofs. Soil temperatures were re-corded by data loggers located 2cm beneath the soil surface, providing four recordings each day. The relationship between soil temperature para-meters and vegetation cover was tested by Prin-ciple Component Analyses (PCA), regression and correlation analyses, and presented as box plot figures. The statistical results indicate that vegetation abundance is highly negatively corre-lated with soil temperature. The results of the soil temperature measurements demonstrate that, apart from two roofs, soil temperatures varied within an optimum range.