Multiscale modeling of shrub biomass and analysis of carbon pool characteristics in arid and semi-arid regions: a case study of the Hubq Desert, Inner Mongolia of northern China

Objective Shrub ecosystems possess unique biological characteristics. To improve the carbon accounting system in arid regions and enhance regional carbon sink management efficiency, this study systematically evaluated the carbon storage characteristics of three typical shrubs in the Hubq Desert, Inner Mongolia of northern China, providing methodological support for carbon balance accounting in desert ecosystems.

Method For the three typical shrubs of Salix psammophila, Caragana korshinskii and Haloxylon ammodendron in the Hubq Desert, we used quadrat surveys and drone remote sensing imagery to quantify regional carbon storage; constructing the optimal prediction model for shrub biomass (M), crown area (C), and volume (V) through sample plot investigation; using drones to obtain shrub coverage and establish a relationship model between biomass and coverage. The regional ecosystem carbon storage is the sum of model-estimated shrub carbon storage and the measured soil and litter carbon storage.

Result (1) The biomass of S. psammophila (M_S = 0.563C^2.563, R² = 0.710, P < 0.001) and C. kroshinskii was most strongly correlated with crown area (M_C = 1.776C^1.315, R² = 0.873, P < 0.001), while the biomass of H. ammodendron was most closely related to shrub volume (M_H = 1.694V^0.952, R² = 0.585, P < 0.001). (2) Regression models for biomass based on shrub cover were established for S. psammophila (R² = 0.896, P < 0.001), C. korshinskii (R² = 0.861, P < 0.05), and H. ammodendron (R² = 0.937, P < 0.001). (3) Carbon storage of ecosystem in the study area ranged in 50.12−59.33 t/ha, with soil, biomass (shrubs and litter) accounting for 46.68−53.87 t/ha and 3.38−6.53 t/ha, respectively. The average contribution rates of soil, biomass (shrubs and litter) to the carbon storage of the ecosystem were 90.52% and 9.48%, respectively.

Conclusion The biomass equations for three typical shrubs constructed in this study fill the gap of shrub species in the Chinese Certified Emission Reduction-14-001-V01 and calculate the carbon storage of shrublands in the study area. This lays the foundation for more scientifically assessing and managing the shrub ecosystems in the Hubq Desert region, thereby enhancing their role in regional carbon sequestration.