**5. Conclusions**

This study produced a new global estimate of mangrove AGB for the year 2004, resulting in a 250-m resolution map that will be publicly available (http://www.3decology.org). This product was generated using methodology that was successfully implemented previously to estimate nation-wide forest AGB for China as well as global forest AGB. Three GLAS parameters and an additional nine predictor variables were used to build a random forest estimation model using plot measurements collected from published literature and free-access datasets. Based on this mangrove AGB analysis, global mangrove AGB density was estimated to be approximately 115.67 (±48.89) Mg/ha on average, with a total global AGB for mangrove forests of 1.52 Pg. Our product was compared to published global mangrove AGB products, and it has better explanatory power ( *R*<sup>2</sup> = 0.48, *RMSE* = 75.85 Mg/ha) than previous climate-based models. Results showed that this estimated global mangrove AGB storage was similar to that predicted by other remote sensing methods, especially the mangrove AGB map produced by Simard et al. [53]. Future research will include better LiDAR-based measurements of mangrove biomass as well as additional factors known to a ffect mangrove distribution.

**Author Contributions:** Conceptualization, T.H., Y.Z. (YingYing Zhang), Y.S. and Q.G.; Data curation, T.H., Y.Z. (YingYing Zhang), Y.Z. (Yi Zheng) and G.L.; Formal analysis, T.H., Y.Z. (YingYing Zhang) and Y.S.; Writing—original draft, T.H. and Y.Z. (YingYing Zhang); Writing—review & editing, T.H., Y.S. and Q.G. All authors have read and agreed to the published version of the manuscript.

**Funding:** This study Supported by the National Key R&D Program of China (2017YFC0503905).

**Acknowledgments:** Thanks to the Center for International Forestry Research (CIFOR, https://www.cifor.org/) for providing mangrove field data.

**Conflicts of Interest:** The authors declare no conflict of interest.
