Comparisons of Species Diversity of Intensive Green Roofs between Honolulu, USA, and Guangzhou, China

The environment on a green roof is considerably different from the terrene environment in terms of soil construction, temperature, atmosphere, wind and solar irradiation. Plants on green roofs are purposefully selected for better adaptation to severe ecological and environmental conditions. Guangzhou, China and Honolulu, USA are two cities with a similar climate and geography. We randomly selected eight intensive green roofs in each city to compare the species diversity of plant communities present on these green roofs, as measured by Abundance, Jaccard’s index, Shannon-Wiener Index, and Evenness. According to our data, Abundance, Shannon-Wiener Index, and Evenness were interdependent to some degree, and higher Abundance and Shannon-Wiener index was associated with higher Evenness. Species diversity was higher in Guangzhou compared to Honolulu. The Jaccard’s index demonstrated that more than 30 plant species were present on green roofs in both cities. A reference list of more than 200 plant species used in green roofs was compiled from both cities for the entire study area. The total number of plant species was 24.8% greater in Guangzhou than in Honolulu. This reference list will be valuable for those creating green roofs in cities with tropical and subtropical climates.

Keywords: Green Roofs, Species Diversity, Field Investigation, Reference List