Importance of urban green areas' connectivity for the conservation of pollinators

Urbanization is one of the main processes generating large changes on the Earth's surface. The remaining green spaces within cities can be of utmost importance for pollinator conservation. Through a systematic literature review, we evaluate how the connectivity of urban green areas (parks, gardens, squares, among others) in different cities can affect the richness and abundance of pollinators. We utilize a connectivity metric using satellite images corresponding to 241 urban green areas obtained from 20 published works. The green areas were classified in urban, peri-urban and non-urban according to their percentage of impervious surface estimated in each image. The metric relates the connectivity of green areas contained within images with a radius of 500 m immersed within a city. Our study shows the richness and abundance of pollinators is positively correlated with the connectivity of green areas in sites with different degrees of urbanization, mainly in urban and peri-urban sites. Our results emphasize the importance of green spaces to maintain the pollinator's community in cities, and suggest that proper design and/or management could improve conditions for these important insects.