Aboveground Biomass Mapping and Analysis of Spatial Drivers in the Qinghai–Xizang Plateau Permafrost Zone: A Case Study of the Beilu River Basin

• Published in: Plants
• Main Authors: Yamin Wu, Jingyi Zhao, Ji Chen, Yaonan Zhang, Bin Yang, Shen Ma, Jianfang Kang, Yanggang Zhao, Zhenggong Miao
• Format: Article in Journal/Newspaper
• Language: English
• Published: MDPI AG 2024
• Subjects: aboveground biomass; Qinghai–Xizang Plateau; random forest; geodetector; alpine grassland; permafrost; Botany; QK1-989; Active layer thickness
• Online Access: https://doi.org/10.3390/plants13050686; https://doaj.org/article/47ba8a3383aa4a628c6f5d2dc16a4a8a

Aboveground biomass (AGB) serves as a crucial measure of ecosystem productivity and carbon storage in alpine grasslands, playing a pivotal role in understanding the dynamics of the carbon cycle and the impacts of climate change on the Qinghai–Xizang Plateau. This study utilized Google Earth Engine to amalgamate Landsat 8 and Sentinel-2 satellite imagery and applied the Random Forest algorithm to estimate the spatial distribution of AGB in the alpine grasslands of the Beiliu River Basin in the Qinghai–Xizang Plateau permafrost zone during the 2022 growing season. Additionally, the geodetector technique was employed to identify the primary drivers of AGB distribution. The results indicated that the random forest model, which incorporated the normalized vegetation index (NDVI), the enhanced vegetation index (EVI), the soil-adjusted vegetation index (SAVI), and the normalized burn ratio index (NBR2), demonstrated robust performance in regards to AGB estimation, achieving an average coefficient of determination ( R 2 ) of 0.76 and a root mean square error ( RMSE ) of 70 g/m 2 . The average AGB for alpine meadows was determined to be 285 g/m 2 , while for alpine steppes, it was 204 g/m 2 , both surpassing the regional averages in the Qinghai–Xizang Plateau. The spatial pattern of AGB was primarily driven by grassland type and soil moisture, with q-values of 0.63 and 0.52, and the active layer thickness (ALT) also played a important role in AGB change, with a q-value of 0.38, demonstrating that the influences of ALT should not be neglected in regards to grassland change.