Native-plant landscaping enhances floral visitation by insects and birds in residential yards

Source abstract

Native plant landscaping is gaining traction in cities worldwide for its potential to enhance biodiversity and ecosystem function. However, it remains unclear to what extent native plants increase animal-floral interactions compared to conventional landscaping such as lawns and ornamental plants. We quantified insect and bird flower visitation networks in 31 residential yards across Greater Los Angeles, California. We also assessed whether native plants in low-income areas, often lacking green amenities (the luxury effect), can support diverse floral-visitation networks. From April to September 2023, we conducted three visits each to 18 paired yards (one native-planted, one conventional) and 13 additional native-landscaped yards. We used timed area searches to quantify insect and bird floral visitation and collected predictor data on air quality, temperature, plant cover, species identity, flower color, phenology, as well as housing prices. Native-landscaped yards supported 4× higher floral-visitor abundance and 1.5× higher richness than conventional yards, largely driven by bees (Apidae) and hoverflies (Syrphidae), which were positively associated with native plant richness, flower-color diversity, and housing price. Several native plant species, including California buckwheat ( Eriogonum fasciculatum ) and white sage ( Salvia apiana ) anchored interaction networks. Moreover, native-landscaped yards contained 2.9× more interactions (140 vs. 48 edges) and exhibited higher network connectivity and redundancy. Floral visitors used native plants disproportionately, with native plants receiving 88% of visits despite representing 80% of availability. Landscaping with native plants can bolster urban insect and bird floral networks, particularly in low-income areas, thereby improving ecosystem functioning in the core of cities.