Abstract: Cities create a wide array of impacts on the broader ecosystem, dramatically changing both biotic and abiotic attributes of landscapes from prior patterns. Vegetation provides a vast array of ecosystem services to urban systems, including biodiversity conservation, absorption of air pollutants, and oxygen generation. Many cities seek to regulate these ecosystem services, as well as provide aesthetic guidance for greening built areas with vegetation to improve stormwater management and improve the physical and mental health of people, as well as other socio-economic improvements and benefits. In this study, we examine municipal ordinances to identify biodiversity conservation efforts on private properties across US cities. We use a text mining approach to analyze a set of publicly available green roof ordinances (GROs) and landscape ordinances (LOs) for their ecosystem services relevant recommendations, with specific focus on biodiversity conservation and pollinator habitat creation.Our research consists of: (1) identifying city codes with LOs and GROs; (2) extracting relevant keywords, and (3) using these insights to support our text mining model development. We then use these data to conduct a geospatial analysis of trends in LOs and GROs.
We identified 50 cities with populations above 100,000 people to collect GRO and LO documents from. Documents were identified by using a search engine to find municipal webpages and published codes in order to identify relevant documents. By using the search term “landscape ordinance” 52 cities were identified, 2 of which were international and excluded from the review. Collected LOs and GROs were queried for 10 relevant keywords, including “biodiversity”, “pollinator”, “native”, and “ecosystem”. Landscape ordinances from 27 states were reviewed in the initial sample and a text mining algorithm was trained. We developed a scalable and replicable text mining method using open source tools. Among our training data, a minority of municipalities had GROs while nearly half of all cities had specific landscape ordinances. Among the 45% of cities with specific LOs,only 14% of those cities promote native biodiversity conservation. Among GROs, 18% of guidelines focussed on stormwater management. Our collated data will be used to build an online open-source map-based compilation of guidelines and regulations to determine spatial trends in landscape and green roof ordinances. Future steps will include analyzing the city codes of the largest 300 US cities.
