Integrating species distribution and piecewise linear regression model to identify functional connectivity thresholds to delimit urban ecological corridors

Urban ecological corridors are essential for sustainable urban development, but determining their width remains challenging. This paper addresses this issue by focusing on the unique habitat requirements of urban under- canopy bird species. We employ Species Distribution Model to simulate their potential living spaces in Shanghai and quantify their functional connectivity in urban mobility. We then use segmented linear regression models to identify turning points in functional connectivity within different buffer zones, which represent the physical width of the corridor. Our findings show that urban undercanopy birds are less sensitive to human activity and building distribution compared to surface temperature, land cover types, and vegetation canopy height. We also find that conventional linear weighting methods tend to overestimate the impact of environmental factors on undercanopy birds, leading to subtle deviations in corridor path recognition. Finally, we demonstrate that employing segmented linear regression helps to quantify the turning points of functional connectivity for each urban ecological corridor, allowing us to determine their physical width range. This study is the first attempt to quantitatively assess the functional connectivity of urban ecological corridors from the perspective of under- canopy birds and demarcate their extent.