Managing urban green spaces in the City of Slunj has never been more challenging due to the constant pressure of urbanization of space and fast-growing tourism. Managing green areas definitely facilitates the list of woody species available in the urban space of the City of Slunj. This inventory creates a basic database of the quantity, species, height and diameter of measured trees, their geographical location and purpose in space. The database itself can be created in the GIS system, but it requires knowledge, and a lot of time. This paper demonstrates the efficiency of the pipGIS® application system, with knowledge of dendrology and knowledge of the use of forestry tools such as: diameter and altimeter .The measurement was held at three interesting locations: Dr. Franjo Tudjman Square , Zrinski and Frankopan Square and the treeline and interesting trees of Rastoke . Measurement is facilitated by the Odk collect application, which is an integral part of the pipGIS® application system. It sends data from the field directly to the web database. After the field part, the data is edited to get a precise image from the field in digital version. During the measurement, a lot of damaged trees were noticed from the regular maintenance of public areas, tree diseases, and even invasive species. The measurement results are shown in tables and graphs in the my final work.