A study tested whether increasing volume of understory vegetation and native vegetation affected effects on bat, bird, and insect populations in urban Melbourne. When increasing understory volume from 10% to 30%, researchers observed 30% to 120% higher occupancy by bats, native birds, beetles, and bugs. The study also found that increasing proportion of native vegetation from 10% to 30% resulted in 10% to 140% higher occupancy across all native taxa.
Threlfall, Caragh G., Luis Mata, Jessica A. Mackie, Amy K. Hahs, Nigel E. Stork, Nicholas S. G. Williams, and Stephen J. Livesley. Increasing biodiversity in urban green spaces through simple vegetation interventions. Journal of Applied Ecology, 54 (2017): 1874-1883. https://doi.org/10.1111/1365-2664.12876.