Effects of ecological control line on habitat connectivity: A case study of Shenzhen, China

• Species distribution points were used to identify important habitats for several species. • Watersheds were classified by cluster analysis of habitat suitability for species. • Through the circuit theory model, the migration probability of species is obtained. • Difference-in-differences method was used to explore the impact of ecological control line policy on habitat connectivity. • Habitat connectivity protection schemes were proposed for different habitat quality zones. Ecological control line (ECL) has become an important policy for enhancing ecological conservation and achieving sustainable urban development. Landscape connectivity of ecological network provides a method for exploring the effect of ECL policy on biodiversity conservation. This study used Shenzhen as an example to analyze the distribution of important habitats based on species occurrence points, environmental factors and artificial neural network methods. Four-phase ecological networks of focal species ( Ardea cinerea, Callosciurus erythraeus, Copsychus saularis, Egretta garzetta, Pycnonotus sinensis ) in 2000, 2010, 2015, and 2020 were constructed, and the effects and changes of ECL on habitat connectivity of species, geographical zone, and species zone scales were sequently analyzed using the difference-in-difference method. The results showed that: (1) Forty-one important habitats were identified, with a total area of 743 km 2 , and the average area of each habitat was 18.1 km 2 . The number of ecological corridors and the area of ecological pinch points in Shenzhen decreased in the first ten years but remained stable over the final ten years. (2) ECL delineation can promote habitat connectivity of regional species and with the passage of time, this promoting effect increases. The protective effect in the high habitat quality zone was greater than that in the low habitat quality zone. (3) City managers can develop habitat connectivity conservation schemes for different species according to the five habitat quality zones: high, mid-high, middle, mid-low, and low. This study proposes a method to assess the effectiveness of the existing ecological control line, and provide a scientific basis for formulating, adusting and optimizing ecological management.