Percolating spatial scale effects on the landscape connectivity of urban greenspace network in Beijing, China

The construction of an urban green network is increasingly recognized as an effective spatial approach to counteract landscape fragmentation through landscape connectivity conservation. Despite the growing awareness of the importance of “spatial scale”, how to identify critical spatial thresholds and evaluate the consequential ecological effects of spatial scales on the landscape connectivity of urban green network, remains a significant challenge. We examined the effects of spatial scale on the landscape connectivity of urban green networks by detecting critical stepping-stone patches and landscape corridors that maximizes the conservational effectiveness of urban green networks. Our study area is located in the central area of Beijing, China, with a monsoon-influenced humid continental climate. We proposed a graph-based percolation model to simulate the percolation patterns and processes of the landscape connectivity of the urban green network in Beijing. The bond and site percolation models were used to identify critical spatial thresholds in core greenspace patches and landscape dispersal corridors by monitoring the spatial feedback patterns within and across the levels of node, cluster and network. Our study revealed that the landscape connectivity of urban green network exhibited multiple sudden state transitions against percolations. The percolation simulation also demonstrated that the landscape connectivity patterns display divergent ecological patterns and processes across nodal, cluster and network levels. Additionally, the results also identified the existence of critical spatial thresholds, at which urban green network becomes drastically fragmented if such critical “stepping-stone” patches and corridors were destroyed.