Student Research Reports

This student research assesses the ecological value of urban tree lines in Karlovac (Croatia), focusing on the “Black Promenade” alley located along the eastern edge of the historic “Karlovac Star” fortification. In spring 2025, detailed biometric measurements were conducted for all 178 trees following GLOBE protocols, including species identification, circumference at breast height, total height, and geolocation, while tree age was estimated using species-specific age factors. Based on these field data, diameter at breast height (DBH) was derived and used to estimate dry biomass, stored carbon, and lifetime CO₂ uptake. The results indicate a mean tree age of approximately 99 years, with an estimated total of about 99 t of stored carbon and roughly 364 t of CO₂ absorbed over the lifetime of the avenue trees. Size-class analysis highlights that medium-to-large diameter trees account for a disproportionately high share of total carbon storage, underscoring the importance of conserving mature, large trees as a key component of the urban “carbon bank.” In addition, a comparison between field measurements and satellite-based platforms (GEDI/Landsat, Earth Engine) reveals limitations of satellite products in dense urban settings (data gaps and pixel-level averaging), reinforcing the need for systematic ground-based research.