Exploring Biodiversity Through Citizen Science: A Case Study of Green Roofs at the Calouste Gulbenkian Foundation Garden in Lisbon

Citizen science is rising and expanding as an approach to data collection, enabling the acquisition of data through the voluntary involvement of citizens in scientific activities. This study explores the effectiveness of citizen science in collecting biodiversity data in urban green infrastructure, focusing on a case study at the Calouste Gulbenkian Foundation in Lisbon, which includes both green roofs and traditional garden areas. Data collected via the iNaturalist platform through structured and unstructured citizen science activities were analyzed to compare patterns of biodiversity observation. Results show that unstructured activities attract more participants but produce fewer observations per person, mainly focusing on more familiar taxa, such as birds. In contrast, structured events concede a higher number of observations per observer, including less commonly recorded taxa like insects, and provide greater coverage of green roofs, since routes are predefined. Seasonal and temporal trends were also noted, with a higher concentration of observations in spring and summer and a significant increase on weekends, indicating the influence of participants’ availability. Spatial observations show that combining gardens and green roofs provides continuous and rich ecosystems that are crucial for city urban planners.