Savannas constitute a mixture of trees and shrub patches with a more continuous herbaceous understory. The contribution of this biome to the soil organic carbon (SOC) and above-ground biomass (AGB) carbon (C) stock globally is significant. However, they are frequently subjected to land use changes, promoting increases in CO2 emissions. In Uruguay, subtropical wooded savannas cover around 100,000 ​ha, of which approximately 28% is circumscribed to sodic soils (i.e., subtropical halophytic wooded savannas). Nevertheless, there is little background about the contribution of each ecosystem component to the C stock as well as site-specific allometric equations. The study was conducted in 5 ​ha of subtropical halophytic wooded savannas of the national protected area Esteros y Algarrobales del Río Uruguay. This work aimed to estimate the contribution of the main ecosystem components (e.g., soil, trees, shrubs, and herbaceous plants) to the C stock. Site-specific allometric equations for the most frequent tree species and shrub genus were fitted based on basal diameter (BD) and total height (H). The fitted equations accounted for between 77% and 98% of the aerial biomass variance of Neltuma affinis and Vachellia caven. For shrubs (Baccharis sp.), the adjusted equation accounted for 86% of total aerial biomass. C stock for the entire system was 116.71 ​± ​11.07 ​Mg⋅ha−1, of which 90.7% was allocated in the soil, 8.3% in the trees, 0.8% in the herbaceous plants, and 0.2% in the shrubs. These results highlight the importance of subtropical halophytic wooded savannas as C sinks and their relevance in the mitigation of global warming under a climate change scenario.

中文翻译：

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乌拉圭盐生林木稀树草原碳储量估算：一种生态系统方法


稀树草原由乔木和灌木斑块组成，具有更连续的草本林下。该生物群落对全球土壤有机碳 （SOC） 和地上生物量 （AGB） 碳 （C） 存量的贡献是显着的。然而，它们经常受到土地利用变化的影响，导致二氧化碳排放量增加。在乌拉圭，亚热带林木稀树草原占地约 100,000 公顷，其中约 28% 被限制在钠质土壤（即亚热带盐生林木稀树草原）上。然而，关于每个生态系统组成部分对 C 储量的贡献以及特定地点的异速生长方程的背景很少。该研究是在乌拉圭 Esteros y Algarrobales del Río 国家保护区的 5 公顷亚热带盐生林稀树草原中进行的。这项工作旨在估计生态系统主要组成部分（例如土壤、树木、灌木和草本植物）对 C 储量的贡献。根据基径 （BD） 和总高度 （H） 拟合最常见的树种和灌木属的地点特异性异速生长方程。拟合方程占 Neltuma affinis 和 Vachellia caven 空气生物量方差的 77% 至 98%。对于灌木 （Baccharis sp.），调整后的方程占总空气生物量的 86%。整个系统的碳储量为 116.71 ± 11.07 Mg⋅ha-1，其中 90.7% 分布在土壤中，8.3% 分布在树木中，0.8% 分布在草本植物中，0.2% 分布在灌木中。这些结果强调了亚热带盐生树木稀树草原在 C 下沉时的重要性，以及它们在气候变化情景下缓解全球变暖的相关性。