Annual maps of forests in Australia from analyses of microwave and optical images with FAO forest definition

Yuanwei Qin (1) , Xiangming Xiao (1) , Wigneron J.-P. (2) , Philippe Ciais (3) , Josep G. Canadell (4) , Martin Brandt (5) , Xiaojun Li (2) , Lei Fan (6) , Xiaocui Wu (1) , Hao Tang (7) , Ralph Dubayah (8) , Russell Doughty (9) , Qing Chang (10) , Sean Crowell (1) , Bo Zheng , Kevin Neal (1) , Jorge A. Celis (1) , Berrien Moore (11)

1 OU - University of Oklahoma
2 UMR ISPA - Interactions Sol Plante Atmosphère
3 LSCE - Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette]
4 CSIRO - Data61 [Canberra]
5 IGN - Department of Geosciences and Natural Resource Management [Copenhagen]
6 NUS - National University of Singapore
7 Southwest University [Chongqing]
8 Department of Geographical Sciences [College Park]
9 Division of Geological and Planetary Sciences [Pasadena]
10 Indiana University [Bloomington]
11 Tsinghua Shenzhen International Graduate School [Shenzhen]

The Australian governmental agencies reported a total of 149 million ha forest in the Food and Agriculture Organization of the United Nations (FAO) in 2010, ranking sixth in the world, which is based on a forest definition with tree height>2 meters. Here, we report a new forest cover data product that used the FAO forest definition (tree cover>10 % and tree height>5 meters at observation time or mature) and was derived from microwave (Phased Array type L-band Synthetic Aperture Radar, PALSAR) and optical (Moderate Resolution Imaging Spectroradiometer, MODIS) images and validated with very high spatial resolution images, Light Detection and Ranging (LiDAR) data from the Ice, Cloud, and land Elevation Satellite (ICESat), and in situ field survey sites. The new PALSAR/MODIS forest map estimates 32 million ha of forest in 2010 over Australia. PALSAR/MODIS forest map has an overall accuracy of ~95% based on the reference data derived from visual interpretation of very high spatial resolution images for forest and nonforest cover types. Compared with the canopy height and canopy coverage data derived from ICESat LiDAR strips, PALSAR/MODIS forest map has 73% of forest pixels meeting the FAO forest definition, much higher than the other four widely used forest maps (ranging from 36% to 52%). PALSAR/MODIS forest map also has a reasonable spatial consistency with the forest map from the National Vegetation Information System. This new annual map of forests in Australia could support cross-country comparison when using data from the FAO Forest Resource Assessment Reports.

Domaines: Planète et Univers [physics]

Yuanwei Qin, Xiangming Xiao, Wigneron J.-P., Philippe Ciais, Josep G. Canadell, et al.. Annual maps of forests in Australia from analyses of microwave and optical images with FAO forest definition. Journal of Remote Sensing (Online), 2021, 2021, pp.9784657. ⟨10.34133/2021/9784657⟩. ⟨insu-03660158⟩