Designing IoT Sensor Networks for Microclimate Monitoring Across the Urban–Forest Gradient: From Urban Heat Drivers to Forest Buffering Mechanisms

Urbanization intensifies microclimatic heterogeneity along the urban–forest gradient, where built morphology, vegetation structure, and hydrological processes interact to shape local thermal conditions. This systematic review synthesizes advances in IoT-based microclimate monitoring across open urban environments, urban forests, and peri-urban forest ecosystems. Following PRISMA 2020 guidelines, 426 records were identified, of which 63 met the eligibility criteria, and 34 core studies were analyzed in depth. In open urban environments, air temperature and relative humidity are predominantly governed by urban morphology and radiative properties. In contrast, forest microclimate is regulated through structural and ecohydrological mechanisms, where canopy structure, edge effects, and water availability determine the stability and depth of microclimatic buffering. Structural simplification and disturbance reduce buffering capacity, whereas canopy continuity enhances thermal stability. IoT-based and low-cost sensor networks enable high-resolution, multi-scale monitoring of these dynamics; however, methodological heterogeneity limits cross-site comparability. By integrating urban climate research with forest microclimate ecology, this review proposes a conceptual and methodological framework for designing distributed sensor networks capable of capturing microclimatic variability along the urban–forest gradient and supporting climate adaptation strategies.