Assessing habitat fragmentation in highly urbanized area: Implications for mitigating landscape dissection and habitat restoration

Effective measurement and monitoring of habitat fragmentation are essential for achieving the United Nations' Sustainable Development Goals, especially given the ongoing global expansion of urbanization. However, current researches primarily address habitat connectivity or landscape dissection separately, while neglecting the impact of landscape dissection on habitat pattern. In this study, we adopt Road network tiles (RNTs, created through the dissection of the landscape by road networks) as analytical units and develop an integrated index of effective habitat network area to assess habitat fragmentation (structural connectivity), with particular emphasis on landscape dissection. Furthermore, a connection efficiency index is proposed to quantify the ratio of current habitat connectivity to its maximum potential. Collectively interpreting these indices reflects both the adverse effects of road expansion on habitat patterns and the effectiveness of mitigation efforts in spatial planning. These indices were applied to the Beijing-Tianjin-Hebei (BTH) region of China. The results show that the effective area of habitat networks in the BTH region declined from 887.66 km2 to 488.50 km2 from 2007 to 2018, despite an overall increase in total habitat area. Nevertheless, connection efficiency for most cities in the BTH region has improved, suggesting that habitat connectivity in 2018 was more efficient and closer to its maximum value compared to 2007, potentially due to effective landscape management practices. By incorporating urban permeation into the joint analysis with RNTs, key zones for habitat conservation and restoration can be identified. This study offers a novel and efficient approach to quantifying habitat fragmentation, providing valuable insights for decision-making aimed at mitigating the negative impacts of urbanization on habitat pattern.