Effects of vegetation strata and human disturbance on bird diversity in green areas in a city in southern Chile

Abstract

Background: Urbanisation is a dominant geographical trend and an important component of global change, with unprecedented implications for socioeconomic , cultural and environmental characteristics. However, green areas, including original fragments, can help to conserve native diversity, improving the functioning of these artificial systems in the long term. Urban areas can still provide habitats usable by wild birds, however the structural characteristics of the habitat formed by different types of green area differ, and therefore dissimilar bird diversities are to be expected. The object of this study was to characterise the α and β diversities of birds in different green areas and to analyse how diversity relates to ten variables that characterise the habitat. Methods: We studied the green areas in the city of Temuco, southern Chile (Park, Square and Median strips of main streets), evaluating the variables: (a) surface area, (b) vegetation, (c) estimated human impact as the proportions of vegetation and bare soil by area, and the vehicle traffic. The bird assemblage structures were characterised by α (intraenvironment) diversity and β diversity (between environments) and the statistical analysis identified the environmental variables related with the presence and abundance of birds. A statistical model was constructed to describe the contribution of the variables to bird diversity. Results: We found significant differences between the diversity of bird species in the three types of green area. The β showed medium to high similarity between the different study units. There was a negative correlation with bare soil areas; the correlations with vehicle flow, plant structure and tree and shrub cover were not significant, meaning that these variables did not explain the variation in the richness of bird species between the green areas. However the surface area did explain this variation presenting a positive potential relation. There was also a high correlation with the origin (native) of shrub species. Conclusions: The bird diversity varied significantly according to the type of urban green area. The environmental variables presenting significant correlations with bird diversity were: surface area, native species of shrub stratum, shrub cover, and bare soil area. The best multiple regression model showed that the three most important variables for bird diversity are the surface area of the green area, the cover of the shrub stratum and the presence of native shrub species.

The effect of habitat changes along the urbanization gradient for breeding birds: an example from the Xiong’an New Area

“…Abundant tree species and substantial maturity of vegetation vertical structure could supply food and habitats for more bird guilds (Canedoli, Manenti & Padoa-Schioppa, 2018). Some studies also have found a positive influence of canopy cover (Schuetz & Schulze, 2015; Threlfall et al, 2017), although shrub cover seems to be more important for both the alpha- (Newman et al, 2018) and beta-diversities (Munoz-Pedreros et al, 2018) of bird species. The deficiency in shrub cover within our study area was probably one of the major reasons for the poor state of the total avian community.…”

“…For example, most bird species positively respond to habitat area (Carbo-Ramirez & Zuria, 2011; Chaiyarat et al, 2019; Lepczyk et al, 2017), though the response may decrease when patch area reaches a threshold (Kim, Chae & Koo, 2007). Increased coverage of trees (Rega-Brodsky & Nilon, 2017), shrubs (Munoz-Pedreros et al, 2018), and vegetation structure heterogeneity due to different tree ages and large or multiple canopy layers (Franklin & Van, 2004; Lindenmayer, Franklin & Fischer, 2006) seem to be crucial for avian species richness (Chong et al, 2014; Lee & Rotenberry, 2015). The effect of shrubby and herbaceous species is probably exerted through the insect communities they sustain (Huang et al, 2015), which is consistent with the results of studies that have emphasized the importance of vegetative food resources (Chace & Walsh, 2006).…”

Niche Analysis and Conservation of Bird Species Using Urban Core Areas

“…In addition, environmental variables at the local scale are often more important than regional ones in determining species distribution and community composition in urban landscapes [38][39][40][41]. Such variables include patch level variables (e.g., green space size, amount of gray, tree, shrub and bare ground cover [6,26,35,42]), matrix level variables (e.g., distance from the city edge and center, building height [37,43,44]) and disturbance variables (e.g., anthropogenic noise, pedestrian and car traffic [45][46][47]).…”

Wintering waterbird assemblage in an emerging wetland of West Bengal, India: characterization for conservation management

“…The positions and numbers of vintage points were placed randomly in view of the size of the wetland. Waterbirds counts from all points were repeated at a regular interval of 7days and for each site, counting period lasted for 10 min to minimize the counting errors (Sarkar et al 2014, Muñoz-Pedreros et al 2018, Issa 2019. Birds were counted from each sighting point with a 25 m radius covering 360° arc (Hutto et al 1986, Issa 2019.…”