Carbon stocks and net ecosystem production changes with time in two Italian forest chronosequences

Abstract

Forest management influences several ecosystem processes, including carbon exchange between forest ecosystem and atmosphere. The aim of this paper was to study the carbon cycle over different age classes of two managed forests in the Italian Alps through direct measurements and modelling. For this purpose, ecosystem carbon dynamics of a beech forest (Fagus sylvatica L.) and of a spruce forest (Picea abies (L.) Karst.) were investigated using a chronosequence approach. In both forests, five forest development stages were identified (thicket, pole wood, young forest, mature forest and the regeneration phase) with an age spanning from 42 to 163 years for the beech forest and from 35 to 161 years for the spruce forest. Measured total ecosystem carbon stock increased up to 80–100 years, with a mean of 232 MgC ha-1 in the beech forest and of 299 MgC ha-1 in the spruce forest. Calculated net ecosystem production (NEP) was found to decrease linearly with age and had an average value of 2.2 and 4.4 MgC ha-1 year-1 for beech and spruce forest, respectively. Model simulations reported an increase in NEP till 50–60 years followed by a decrease thereafter. The model also predicted a negative NEP for a short period (8–11 years) after the seed cut. Aboveground biomass was the main driver of carbon accumulation while soil carbon was not significantly influenced by both age and management system. Moreover, measured data and model showed that the applied shelterwood system allowed for a rapid recovery of the ecosystem after the disturbance (i.e. seed cut), bringing back forest to act as C sink in few years

Nitrogen deposition outweighs climatic variability in driving annual growth rate of canopy beech trees: Evidence from long‐term growth reconstruction across a geographic gradient

“…Age dynamics in height growth might be better explained at population levels, with the assumption that dominant (upper canopy) height is a viable proxy for aboveground productivity, the so‐called Eichhorn's rule (Eichhorn, ); but also see Assmann () and Skovsgaard and Vanclay (). In so doing, our results suggested age‐related constraints on stand productivity were effective rather early in beech forests, as shown by De Simon, Alberti, Delle Vedove, Zerbi, and Peressotti (). On the other hand, aboveground productivity was suggested to remain positive until late developmental stages, consistent with the long‐term net primary productivity patterns observed by Xu et al.…”

Carbon budgets in fertile silver birch (Betula pendula Roth) chronosequence stands

“…In our earlier study (Uri et al, 2012), we found that the C pool in tree biomass increased with stand age, whereas the soil C pool remained stable and thus did not depend on stand age; according to Raich and Nadelhoffer (1989) and Simon et al (2012), there must be equilibrium between the inputs and the outputs, unless significant changes are detected in the soil C storage.…”

A LiDAR-based approach for a multi-purpose characterization of Alpine forests: an Italian case study

“…LMH weights the contribution of trees to the stand height by their basal area, and is more stable than an unweighted mean height, because it is less affected by mortality and harvesting of the smaller trees. Biomass and volume were calculated according the regional allometric relationships proposed by Del Favero et al (2000) and Anfodillo et al (2006) and already applied by De Simon et al (2012) in the Region.…”