Urban-rural gradient in biodiversity intactness across global cities

Identifying the urban-rural gradient in biodiversity variation is crucial to better understand the response of biodiversity dynamics to global urbanization. However, knowledge of this gradient in global cities remains limited, largely due to the constraints of ground-based experiments. In this study...

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Main Authors: Naiyi Liu, Zihan Liu, Felista Kasyoka Kilunda, Yanqi Liu, Chao Qin
Format: Article
Language:English
Published: Elsevier 2025-12-01
Series:Ecological Informatics
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Online Access:http://www.sciencedirect.com/science/article/pii/S1574954125003590
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author Naiyi Liu
Zihan Liu
Felista Kasyoka Kilunda
Yanqi Liu
Chao Qin
author_facet Naiyi Liu
Zihan Liu
Felista Kasyoka Kilunda
Yanqi Liu
Chao Qin
author_sort Naiyi Liu
collection DOAJ
description Identifying the urban-rural gradient in biodiversity variation is crucial to better understand the response of biodiversity dynamics to global urbanization. However, knowledge of this gradient in global cities remains limited, largely due to the constraints of ground-based experiments. In this study, through statistical analyses of global gridded 100 m Biodiversity Intactness Index (BII) data, we find that the global mean BII is 0.40 ± 0.07 and 0.60 ± 0.11 for the urban and rural areas, respectively. Significantly, this urban-rural BII difference was most pronounced in Africa and Asia. There is a notable and pervasive pattern of increasing BII along the urban-rural gradient in global cities. The global mean BII demonstrates an increase from 0.37 ± 0.07 in urban center to 0.63 ± 0.12 in the rural periphery. The difference in BII between the urban center and the rural periphery can reach 0.20 and 0.21 in Africa and Asia, respectively, representing 50 % and 54 % of the total BII in the urban centers. In addition, generalized additive models (GAM) revealed non-linear relationships between biodiversity intactness and key drivers: urban green space (UGS) exhibited threshold effects, with BII increasing significantly when vegetation indices exceeded critical levels (NDVI >0.40, EVI >0.20, VCF >60 %; R2 = 0.58–0.72, p < 0.001). Conversely, economic activity showed a strong negative association with BII (R2 = 0.87, p < 0.001), stabilizing at higher GDP densities (>40 million/km2). The findings contribute to a deeper understanding of the large-scale urban-rural gradient in biodiversity variation and may prove beneficial for the conservation of urban biodiversity.
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spelling doaj-art-39c3a57a7f5e4d1593e7c8143ce59b862025-08-20T05:05:55ZengElsevierEcological Informatics1574-95412025-12-019010335010.1016/j.ecoinf.2025.103350Urban-rural gradient in biodiversity intactness across global citiesNaiyi Liu0Zihan Liu1Felista Kasyoka Kilunda2Yanqi Liu3Chao Qin4School of Life Sciences, Nanjing University, Nanjing 210023, ChinaSchool of Artificial Intelligence, Anhui University, Hefei 230601, China; Corresponding author at: Anhui University at Qingyuan Campus, No.111 Jiulong Road, Hefei, Anhui 230601, China.Sino-Africa Joint Research Centre, Chinese Academy of Sciences, 62000-00200 Nairobi, KenyaSchool of Artificial Intelligence, Anhui University, Hefei 230601, ChinaSchool of Artificial Intelligence, Anhui University, Hefei 230601, ChinaIdentifying the urban-rural gradient in biodiversity variation is crucial to better understand the response of biodiversity dynamics to global urbanization. However, knowledge of this gradient in global cities remains limited, largely due to the constraints of ground-based experiments. In this study, through statistical analyses of global gridded 100 m Biodiversity Intactness Index (BII) data, we find that the global mean BII is 0.40 ± 0.07 and 0.60 ± 0.11 for the urban and rural areas, respectively. Significantly, this urban-rural BII difference was most pronounced in Africa and Asia. There is a notable and pervasive pattern of increasing BII along the urban-rural gradient in global cities. The global mean BII demonstrates an increase from 0.37 ± 0.07 in urban center to 0.63 ± 0.12 in the rural periphery. The difference in BII between the urban center and the rural periphery can reach 0.20 and 0.21 in Africa and Asia, respectively, representing 50 % and 54 % of the total BII in the urban centers. In addition, generalized additive models (GAM) revealed non-linear relationships between biodiversity intactness and key drivers: urban green space (UGS) exhibited threshold effects, with BII increasing significantly when vegetation indices exceeded critical levels (NDVI >0.40, EVI >0.20, VCF >60 %; R2 = 0.58–0.72, p < 0.001). Conversely, economic activity showed a strong negative association with BII (R2 = 0.87, p < 0.001), stabilizing at higher GDP densities (>40 million/km2). The findings contribute to a deeper understanding of the large-scale urban-rural gradient in biodiversity variation and may prove beneficial for the conservation of urban biodiversity.http://www.sciencedirect.com/science/article/pii/S1574954125003590Biodiversity intactness index (BII)UrbanizationUrban-rural gradientGreen spaceVegetation indices (VI)
spellingShingle Naiyi Liu
Zihan Liu
Felista Kasyoka Kilunda
Yanqi Liu
Chao Qin
Urban-rural gradient in biodiversity intactness across global cities
Ecological Informatics
Biodiversity intactness index (BII)
Urbanization
Urban-rural gradient
Green space
Vegetation indices (VI)
title Urban-rural gradient in biodiversity intactness across global cities
title_full Urban-rural gradient in biodiversity intactness across global cities
title_fullStr Urban-rural gradient in biodiversity intactness across global cities
title_full_unstemmed Urban-rural gradient in biodiversity intactness across global cities
title_short Urban-rural gradient in biodiversity intactness across global cities
title_sort urban rural gradient in biodiversity intactness across global cities
topic Biodiversity intactness index (BII)
Urbanization
Urban-rural gradient
Green space
Vegetation indices (VI)
url http://www.sciencedirect.com/science/article/pii/S1574954125003590
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AT zihanliu urbanruralgradientinbiodiversityintactnessacrossglobalcities
AT felistakasyokakilunda urbanruralgradientinbiodiversityintactnessacrossglobalcities
AT yanqiliu urbanruralgradientinbiodiversityintactnessacrossglobalcities
AT chaoqin urbanruralgradientinbiodiversityintactnessacrossglobalcities