Rapid urbanization and climate change pose severe challenges to the sustainable development of the built environment in developing regions

Urban greening is central to climate-responsive planning, but month-to-month variation in urban net primary productivity (UNPP) remains insufficiently resolved. We estimated monthly UNPP from the MOD17A2H Gpp band, a gross primary productivity (GPP) product, across Chengdu’s five central districts during 2013–2022 and examined its associations with the normalized difference vegetation index (NDVI), land surface temperature (LST), precipitation, and night-time light intensity. Ordinary least squares regression used 119 overlapping citywide monthly means from January 2013 to November 2022. The model explained 86.1% of UNPP variance (adjusted R² = 0.856). LST showed the largest standardized association (β = 0.596), followed by NDVI (β = 0.286) and precipitation (β = 0.135); night-time light intensity was not significant (β = 0.017, p = 0.632). HC3-robust inference retained the NDVI and LST associations, whereas the precipitation association weakened. District summaries showed the largest stage-wise UNPP increase in Qingyang and the largest NDVI increase in Chenghua. Greener spatial patterns after 2018 coincided temporally with the Park City Initiative but do not establish a causal policy effect. These findings support temporally aligned monitoring while identifying the need for field-based species, management, and impervious surface data.

In the context of urban renewal, rooftop greening in old buildings plays a vital role in reducing carbon emissions and supporting carbon neutrality goals. This study evaluates the carbon capture capacity (TCO₂) and efficiency (ηCO₂) of rooftop greening under load constraints by developing standardised greening units and mathematical models to quantify CO₂ absorption and self-weight load. Rooftop carbon capture performance is assessed by comparing the quantified TCO₂ of each unit with the theoretical maximum and calculating overall ηCO₂. Three representative species—Hibiscus mutabilis, Prunus cerasifera ‘Atropurpurea’, and Gardenia jasminoides var. radicans—were examined. In single-planting mode, ηCO₂ was approximately 14% with no significant differences among groups, though TCO₂ varied considerably, ranging from 6061.32 g·d⁻¹ for Hibiscus mutabilis to 1515.52 g·d⁻¹ for Gardenia jasminoides var. radicans. In mixed planting, ηCO₂ showed greater fluctuation, with species combinations of similar TCO₂ enhancing efficiency. Findings demonstrate that rooftop greening can effectively expand urban green spaces, improve species diversity, and promote ecological balance, while providing a systematic evaluation framework for low-carbon renovation strategies in urban renewal.