Changes in Conifer Trees’ Wood Density and Forest Carbon Stock Over Time in a Changing Climate
Type: dissertation
Abstract: 37% higher than the carbon stock reported by previous studies for other European temperate forests.As expected, trees were the largest pool, accounting for 64% of the total carbon, followed by soil (19%), deadwood (12%), and litter (1%).In Chapter 3, we analysed the impact of silvicultural techniques on carbon storage.We considered different areas of a montane Norway spruce forest that had undergone different past management.The main outcome of this research is the observation that monolayered forests managed with productive objectives store more carbon than pastured forests, at the expense of their resistance and resilience to natural disturbances.We also showed that, a few decades after withdrawal from regular management, the distribution of carbon in the different pools gradually shifts towards greater prominence of dead biomass.While the carbon stored in trees remains the largest at all stages, deadwood was almost absent immediately after the cessation of regular management.However, within a few decades, it had grown to account for 6% of the aboveground tree biomass.To investigate how trees respond to climate change, we conducted a twoscale analysis.Firstly, as detailed in Chapter 4, we conducted a global scale analysis developing the Weighted Tree-ring Density (WTD), a new proxy for analysing carbon storage.Using WTD, we examined the carbon storage trend from 1800 to 1990 at each age stage, removing the agedependent effect from our analysis.Despite variations across age groups, we found that a general decline in trees' wood density and, consequently, in the amount of carbon potentially stored by trees.Finally, in Chapter 5, we conducted a more in-depth analysis of the carbon storage potential of a Tasmanian conifer species, aiming to quantify the extent of the decline.Our results indicated a potential reduction of approximately 10%.In addition, this study attempted to understand the iii wood anatomical reasons for these variations.Our findings reported an enlargement in tracheid diameter, both radially and tangentially, and a reduction in cell wall thickness.In other words, the wood is becoming less dense, namely less carbon is accumulated.Overall, this doctoral thesis confirms the important role of forests in mitigating climate change, but also highlights their sensitivity to climate variations.Therefore, management techniques that improve forest resistance and resilience, as well as carbon estimation methodologies that account for variations in wood density, should be implemented in future studies of terrestrial forested ecosystems.
Author: BONO, ALESSIA
Language: English
Subfield: Forestry
Domain: Life Sciences
SDGs: Climate action, Life on land
Open Access status: green
OpenAlex ID: W7218274061