Most plant studies of green roof taxa have only been conducted for a duration of 1 or 2 years. The problem with this scenario is that it can result in premature conclusions and misleading recommendations because green roofs are dynamic systems. Plants that initially survive may eventually experience reduced coverage or disappear completely due to competition, variability in climate, and other factors. Setting up long-term studies similar to the National Science Foundation (NSF) Long Term Ecological Research (LTER) model would provide the opportunity to follow changes to green roof habitats over time and also examine impacts and ecosystem service outputs on similarly designed roofs across geographic locations. Without consciously considering the effects and changes over time mistakes are not only made, but also repeated. We review several important longitudinal studies and discuss factors that impact long-term plant communities such as substrate composition and fertility, substrate depth, substrate moisture, microclimates, roof slope, orientation, and irradiance levels; as well as initial plant choices, functional diversity and complexity, and maintenance practices. In addition, we discuss the potential of applying the LTER model to green roofs and close with future research needs and questions.
Rowe, B. (2015). Long-term Rooftop Plant Communities (pp. 311–332). https://doi.org/10.1007/978-3-319-14983-7_13