Abstract:

Old-growth forests play a key-role in reducing atmospheric carbon dioxide (CO₂) concentrations by storing large CO₂ amounts in biomass and soil over time. This quantifies the carbon pool into different forest compartments in three Mediterranean old-growth forests of Southern Italy populated by Pinus laricio, Fagus sylvatica and Abies alba. Ecosystem carbon pools have been assessed per compartment, i.e., living trees, deadwood, litterfall (foliar and woody), roots and 0–20 cm topsoil, combining the whole old-growth forest mass, (i.e., using tree allometric relationships, deadwood factor conversions, root-to-shoot ratios, litterfall and soil samplings) by the respective organic carbon concentrations. The results show the considerable capacity of these forest ecosystems in storing CO₂ in biomass and soil, with carbon pool values ranging from 532.2 to 596.5 Mg C ha⁻¹. Living trees and 0–20 cm topsoil had larger carbon pool, contributing 53.0 and 22.1%, respectively. In most cases, organic carbon concentration was higher (more than 60%) than the average carbon conversion rate of 50%, especially in living trees, deadwood, and woody litterfall. This study contributes further scientific evidence of the capacity of old-growth forests in storing CO₂ in their different compartments, with special evidence on tree biomass, litterfall and mineral soil, thereby highlighting the key role of old-growth forests within the challenge of climate change mitigation.

Key words: Ecosystem carbon pool, Organic carbon concentration, Ecosystem compartment, Climate change mitigation, Carbon forestry