Using environmental DNA(eDNA) for monitoring biodiversity on green roofs – a pilot study in the city of Rotterdam, the Netherlands(2025)

Monitoring abundance and species richness is essential to determine biodiversity trends in cities. Monitoring data is essential for developing effective policies to protect and restore urban ecosystems. In addition to traditional monitoring methods, innovative tools are being used to increase the efficiency and deepness of biodiversity assessments. One of these methods is environmental DNA (eDNA) sampling. In this project eDNA was used to identify and characterize the arthropods (namely insect) species presence on 3 different green roofs and their surroundings. The main goal of the study was to (1) establish a comprehensive arthropods biodiversity baseline for each infrastructure (green roof and its surrounding), (2) to compare the biodiversity metrics between urban infrastructure of three different green roofs (Peperklip, De Doelen, Hofbogen), the effect of vertical zones (surroundings vs. roof) and season (Spring vs. Autumn) and, (3) to correlate pollinator biodiversity with available flowering plant food sources.  

The key findings are: eDNA of 454 genus/species were identified across the three different locations (both arthropods &vertebrates). Arthropods comprised the vast majority of detections (93%, N=422 genus/species), while vertebrates accounted for 7% (N=32 genus/species). The study highlighted a broad taxonomic diversity of 21 different groups, ranging from crawling to flying insects and aquatic arthropods.

For invertebrates, the areas surrounding the roofs had a slightly higher number of species in autumn, while the roofs harboured marginally higher numbers of insects in spring. De Doelen and De Hofbogen roofs, displayed a greater number of unique arthropod species in spring compared to autumn (SGS, 2024).  

Coupled with other monitoring tools, molecular tools such as eDNA seem to be a promising method. This pilot is a good start for achieving results with this method, though more research is needed to draw more solid conclusions. Then results can be used to improve the design of biodiverse green roofs.