Treeline are indicators of climate change in the forested areas, as a result the trees will begrown in the non-forested areas over the period of time. This thesis explores the potential ofusing the ICESat-2 satellite data to detect and map the treeline boundaries in southern Norway.The study focuses on evaluating two data products ATL03 (geolocated photon returns) andATL08 (processed 100 m vegetation segments) and compares them against high resolutionaerial imagery to assess their effectiveness in identifying the treeline positions and vegetationstructure.Four validated locations were selected for studies. The results show that ATL08, due to its100-meter segment resolution and limitations in segment generation under cloud cover, oftenproduces false vegetation signals or misses canopy regions entirely. ATL03, which providesraw photon level information, proved more reliable for identifying vertical vegetation structurewhen used with aerial imagery. However, misclassification caused by clouds, low photondensity, and limitations in the DRAGANN algorithm were notable challenges. ICESat-2 candetect taller vegetation, it lacks the resolution to consistently identify low-stature shrubs orsparse ecotone trees without additional data support like aerial images.Overall, the study demonstrates that ATL03 data can be used for the treeline mapping withreasonable accuracy when validated with aerial imagery. The findings highlight both thepotential and limitations of ICESat-2 spaceborne laser altimeter for vegetation monitoring andsuggest that future improvements such as algorithm development for better classifications andvalidation with UAV and LiDAR datasets to further develop the methodology using ATL03data sets.