This study aims to evaluate the acoustical quality of outdoor acoustic spaces in nature based on soundscape approach. Acoustic taxonomy of sonic events, acoustic itineraries and acoustic calendars were studied at a national park. Long time noise level measurements were performed. In addition, acoustical quality of outdoor acoustic spaces was investigated by impulse response measurements and auralization techniques. A questionnaire was administered to qualitatively evaluate acoustical quality of the acoustic spaces. The results reveal the importance of acoustical evaluation of acoustic spaces in nature. The acoustical quality of sonic events is determined by that of the acoustical spaces that are characterized by natural elements. The sound reflections off the natural surfaces of the acoustic spaces are characterized by the impulse response technique. Subjects with critical listening experience have significantly different perception of sounds in terms of Loudness, Reverberance, Echoes, Naturalness and Musical Quality among different outdoor acoustical spaces.