Biodiversity and urban low-carbon development: an empirical study from Haidian District, Beijing

Urban areas face the dual challenge of mitigating carbon emissions while halting biodiversity loss, yet longitudinal evidence from Asian megacities on whether biodiversity independently enhances carbon sequestration remains limited. This study examines the biodiversity–carbon relationship using a twelve-year panel dataset from Haidian District, Beijing—a highly urbanized region where green space expansion has largely reached its spatial limits. Based on a systematic monitoring network of 40 permanent quadrats across 22 subdistricts, we constructed a comprehensive Biodiversity Index (BD) integrating plant, bird, amphibian, and soil fauna diversity with ecosystem quality and ecological function indicators. Using Generalized Linear Mixed Models (GLMMs) with quadrat and year as random effects, we find that the BD index is positively associated with carbon sink capacity, whereas green coverage alone does not. Plant and bird diversity emerge as positive predictors, with amphibian diversity exhibiting context-dependent effects confined to wetland habitats. The increasing marginal contribution of biodiversity to carbon sinks over time is consistent with a "quality transition" from area-based to quality-driven greening. The findings provide longitudinal empirical evidence that biodiversity restoration is associated with low-carbon development after urbanization stabilizes. Policy implications include integrating biodiversity premiums into carbon accounting, prioritizing functional complementarity in species selection, and protecting ecological corridors that sustain trophic interactions.