Abstract: GNSS RTK could obtain real-time positioning information of high accuracy,and has a broad application prospect in forests.Dual-system GNSS RTK positioning was studied in secondary birth forests of different types of terrains by using quasi-kinetic and fast static surveying operation modes.Results show that 1)The satellite number and spatial geometric distribution, which are the best on ridges than on slope and valley forest,can fulfill RTK positioning;2)The solutions are all fixed with high accuracy on ridge in quasi-kinetic surveying.And most of the solution on slope and valley are floating solution with low accuracy;3)The fix position limiting factors are satellite message quality and multi-path effects instead of satellite number and spatial distribution;4)The high accuracy of cm level is obtained by extending observation time.The longest observation time should not be more than 15min in terms of precision and efficiency.

Key words: RTK surveying, GPS, global navigation satellite system (GLONASS), initialization time, position dilution of precision (PDOP)