Street trees reduce the negative effects ofurbanization on birds

The effects of streets on biodiversity is an important aspect of urban ecology, but it has beenneglected worldwide. Several vegetation attributes (e.g. street tree density and diversity)have important effects on biodiversity and ecological processes. In this study, we evaluatedthe influences of urban vegetationÐrepresented by characteristics of street trees (canopysize, proportion of native tree species and tree species richness)Ðand characteristics of thelandscape (distance to parks and vegetation quantity), and human impacts (human populationsize and exposure to noise) on taxonomic data and functional diversity indices of thebird community inhabiting streets. The study area was the southern region of Belo Horizonte(Minas Gerais, Brazil), a largely urbanized city in the understudied Neotropical region. Birddata were collected on 60 point count locations distributed across the streets of the landscape.We used a series of competing GLM models (using Akaike's information criterion forsmall sample sizes) to assess the relative contribution of the different sets of variables toexplain the observed patterns. Seventy-three bird species were observed exploiting thestreets: native species were the most abundant and frequent throughout this landscape.The bird community's functional richness and Rao's Quadratic Entropy presented valueslower than 0.5. Therefore, this landscape was favoring few functional traits. Exposure tonoise was the most limiting factor for this bird community. However, the average size ofarboreal patches and, especially the characteristics of street trees, were able to reducethe negative effects of noise on the bird community. These results show the importance ofadequately planning the urban afforestation process: increasing tree species richness, preservinglarge trees and planting more native trees species in the streets are managementpractices that will increase bird species richness, abundance and community functionalaspects and consequently improve human wellbeing and quality of life