Abstract: The key to the successful invasion of Spartina alterniflora lies in its ability to grow, reproduce and adaptability to the environment. The biomass of S. alterniflora is an important embodiment of its invasion ability. Taking the unmanned aerial vehicle (UAV) remote sensing image as the data source, this study estimated the above-ground biomass of S. alterniflora through the model which was composed by vegetation coverage and plant height. The results indicate that in the typical area of Tiaozini, the biomass of S. alterniflora is between 0 and 9.13 kg·m^-2 and the average biomass is 0.73 kg·m^-2 with 75.13% of S. alterniflora biomass being less than 0.73 kg·m^-2, 18.47% of S. alterniflora biomass being between 0.73 and 3.00 kg·m^-2; and 6.40% of S. alterniflora biomass being greater than 3.00 kg·m^-2. S. alterniflora with high biomass is mainly distributed in the area near the seawall and the tidal flat towards the seaside. The biomass of S. alterniflora is low between the seawall and the seaside flat. The root mean square error of biomass estimation is 0.76, and the absolute error is between 0.01 and 1.99 kg·m^-2. The above-ground biomass distribution of S. alterniflora in the study area can reflect the inversion results. The distribution of S. alterniflora in the study area is irregular, most of them are distributed in patches. The young S. alterniflora distributed in clusters, which is in the expansion stage of S. alterniflora. The UAV remote sensing method used in this study could simultaneously obtain image of the study area at sampling time, which could be applied to the inversion of biomass with timeline. This study provides a new method for the quantitative inversion of S. alterniflora above-ground biomass.

Key words: unmanned aerial vehicle (UAV), above-ground biomass, vegetation cover, plant height, Spartina alterniflora