New estimates of poplar ecosystem carbon pools based on remote sensing and field surveys of forest carbon sinks

Abstract

Abstract Within the context of global climate change, carbon sequestration by poplar is receiving increasing attention, both in China and globally. However, factors including limited sample sizes, multiple data sources, and inconsistent methodologies have limited accurate estimates of carbon sequestration by poplar to only that of aboveground biomass (AGB) and belowground biomass (BLB) carbon pools; whereas the estimations of forest understory (LGB) and dead wood (KSB) remain uncertain. This study conducted a field campaign involving 123,385 monitoring plots and 163 carbon sink-specific standard plots. The results showed that the total carbon pool of the poplar ecosystem was 413.64 Tg C, of which 98.39% and 1.61% were stored in biomass and dead organic matter, respectively. The carbon densities of different carbon pools exhibited strong correlations with climate, with the carbon sequestration capacities of AGB and BLB first decreasing sharply and then increasing gradually with increasing mean annual temperature (MAT) and mean annual precipitation (MAP), following which they gradually stabilized after exceeding a certain threshold value. The rank of climate variables in terms of their influence on the remaining carbon pools was mean relative humidity (MRH) > MAT > MAP. The results also showed strong correlations between different carbon pools and altitude, slope degree, slope aspect, and slope position. This study provided updated estimates of the carbon pools of poplar ecosystems based on direct field measurements and can provide a valuable reference for the validation and parameterization of carbon models in China and globally.