Carbon stock estimation in halophytic wooded savannas of Uruguay: An ecosystem approach

[Geoengineering News]

https://www.sciencedirect.com/science/article/pii/S2197562024000526?via%3Dihub

Authors 

Andrés Baietto, Andrés Hirigoyen, Carolina Toranza, Franco Schinato, Maximiliano González, Rafael Navarro Cerrillo

https://doi.org/10.1016/j.fecs.2024.100216

10 July 2024

Highlights

•Subtropical halophytic wooded savannas are important C sinks nationally.

•The largest proportion of the C stock in the system is allocated in the soil.

•The trees contain the largest C stock proportion of the total above-ground biomass.

•The conservation of this coverage could be important for climate change mitigation.

Abstract

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.

Source: ScienceDirect