Urban trees play a crucial role in improving microclimatic conditions by reducing temperature and mitigating the urban heat island effect, thereby contributing to climate change mitigation. This thesis assesses changes in the amount of aboveground biomass (AGB) of trees before and after the reconstruction of a section of Linhartova Street in Ljubljana, comparing field measurements with airborne laser scanning (ALS) data. The main objective was to evaluate whether a combination of ALS data (LiDAR) and field measurements provides reliable AGB estimates in an urban environment and to quantify AGB reduction due to tree removal or relocation. Field measurements were conducted on 142 trees, recording their diameter at breast height (DBH), tree height, and species. Based on ALS data from the Municipality of Ljubljana, tree locations and heights were detected using the Forestry FlaiNet algorithm on the online platform Flai (www.flai.ai). Using allometric equations, AGB was calculated through three methods. The results showed that tree heights obtained from ALS data were, on average, 1.1 meters lower than those from field measurements. Additionally, a commission error of 10,13 % was identified, indicating that the algorithm overestimated the number of trees in the ALS data, while the omission error (3,8 %) showed that some trees were not detected by the algorithm. AGB calculations revealed that the method based on field measurements yielded the highest biomass values, whereas the method using modeled DBH and ALS-derived heights underestimated AGB by 27 %. Following the street reconstruction, only 28 % of the original AGB remained in the studied area, representing a 72 % reduction in biomass due to tree removal or relocation.
|
