Publications

Yao, Y; Xiao, XM; Qin, YW; Wang, J; Zhang, CC; Newman, GS; Pan, L; Meng, C; Pan, BH; Yin, CL (2025). Improved annual forest cover maps in Oklahoma from analyses of PALSAR-2, Landsat, and LiDAR data sets during 2015-2021. FRONTIERS OF EARTH SCIENCE.

Abstract
Accurate forest cover maps are the basis for estimating forest biomass and are crucial for climate regulation and biodiversity conservation, especially in sub-humid and semi-arid regions such as Oklahoma, USA. To date, there is very limited data and knowledge of the spatial pattern and temporal dynamics of forest cover in Oklahoma, and current forest cover maps have large uncertainties. In this study, multi-sensor datasets, including the Phased Arrayed L-band Synthetic Aperture Radar (PALSAR-2), Landsat, and spaceborne Light Detection and Ranging (LiDAR), were combined to generate annual forest cover maps for the years 2015 to 2021. Specifically, both PALSAR-derived HV, HH-HV, and HH/HV and Landsat-derived Normalized Difference Vegetation Index (NDVI) were used together to generate annual maps of forest cover and three forest types (evergreen, deciduous, and mixed forest) at 30-m spatial resolution for each year. The canopy height and canopy coverage samples from the Global Ecosystem Dynamics Investigation (GEDI) and the Ice, Cloud, and land Elevation Satellite-2 (ICESat-2) were used to assess forest cover maps. We also compared the spatial distribution and forested area of several forest products. Our results show that using the forest definition (canopy height > 5 m, canopy coverage > 10% over an area of 0.5 ha) of the Food and Agriculture Organization of the United Nations (FAO), the accuracy of resultant PALSAR/Landsat forest cover map for 2019 were 77.4% (GEDI) and 95.6% (ICESat-2). The estimated forested area (51,916 km2) was moderately higher (7.2%) than the forested area from the USDA Forest Inventory and Analysis (FIA) statistics dataset (48,202 km2) in 2017. Between 2016 and 2020, Oklahoma's forested area increased slightly by 1.9%. The PALSAR/Landsat forest maps are more accurate in western Oklahoma compared to other satellite-based forest products. The resultant annual maps of forest cover and three different forest types over Oklahoma can be used to support statewide forest management and conservation.

DOI:
10.1007/s11707-025-1151-4

ISSN:
2095-0209