Aboveground wood biomass, carbon stocks and annual carbon sequestration of floodplain forests in the Danube Delta, Romania

Intact wetlands can act as carbon sinks and mitigate increased amounts of CO2 in the atmosphere emitted by human activities. In addition to the organic soils in reed beds, floodplain forests play an important role in the carbon storage within wetlands. In the context of the project ‘EDAPHIC-BLOOM Danube’ (2020-2023), actions for greenhouse gas (GHG) mitigation were developed to reduce the effects of climate change. One project part dealt with estimates of aboveground wood biomass and carbon stocks of the riparian vegetation in the Danube Delta. The different forest types were investigated in the vegetation periods of 2021 and 2022 using a plot design in which vegetation and site-specific habitat parameters such as substrate and flooding frequency were recorded. Vegetation data was used to calculate the aboveground wood biomass (AGWB) of the trees and determine their carbon stock. Furthermore, tree core samples of the dominant tree species were taken to measure annual AGWB increments for determining carbon sequestration and net primary production (NPP). In total, a carbon stock of almost 2.5 million Mg (t) is stored in the riparian forests covering an area of approximately 30,139 ha in the Danube Delta. ... mehrThe results show differences in AGWB and carbon stocks between natural softwood and hardwood riparian forest types and tree plantations. The individual Populus × canadensis trees in the plantations were found to have the highest annual carbon sequestration in their AGWB (0.0186 Mg year-1). The natural sand dune forests, however, are the most important forest type in terms of long-time carbon storage (approximately 333,315 Mg C in the entire delta). Considering annual growth of the main tree species and the cover of the different forest types, the highest current NPP of the Danube Delta forests is found in natural floodplain forests with almost 97,750 Mg year-1.