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Highlights: [•] The peatland in the current investigation behaved as a net sink for direct CO2 NEE. [•] Key met variables (and their interaction) to describe CO2 exchange were determined. [•] WTL found to influence long-term CO2 exchange for both day and night. [•] Models to describe day and night CO2 exchange developed for weekly and annual time-scales. [•] Indirect and direct contribution to the variation of CO2 exchange quantified. [Copyright &y& Elsevier]

Abstract: The aim of this inventory (acronym: INFOCARB) was to measure the organic carbon stored in the forest ecosystems of the Trento region (Provincia Autonoma di Trento, Northern Italy) in both above- and belowground pools, according to the Kyoto protocol and IPCC requirements. A total of 150 forest sampling points were selected on the entire regional area (6206km2) with a statistical sampling approach, based on the timber volume as a proxy variable for a stratified sampling. Each sampling point was located with a GPS receiver and a 600m2 circular plot was delimited around each point. Inside the plots, the biomass of trees, shrubs and herbaceous vegetation was measured, while litter was collected in systematically placed subplots. Topsoil (down to 30cm depth) was sampled with the excavation method on three systematically located pits, to determine the organic carbon content, the bulk density and the volume occupied by stones and roots. The inventory estimated the regional total carbon content of the forests as 71.9±5.2Tg C, with an average carbon density of 207.01±14.5Mg Cha−1. The aboveground biomass and the soil had a similar carbon content, 43.2% and 44.6% of the total ecosystem carbon, respectively, whereas the root systems and the litter accounted for 9.6% and 2.6%, respectively. Due to the high inter-site variability, only weak statistical relationships were found between the soil carbon content and main ecosystem and climatic variables. However, when dividing the plots into different species-dominated forests, the beech sites differed significantly from the conifer sites in the carbon stock and the C/N ratio in the soil organic layers. [Copyright &y& Elsevier]

Abstract: Northern peatlands contain an estimated 1/3 of the world''s soil carbon pool. This large carbon pool is of concern due to its uncertain future in a changing climate. Blanket bogs are peatlands that occur in temperate maritime regions where precipitation is much greater than evapotranspiration. We describe five years (1 October 2002 to 30 September 2007) of eddy-covariance (EC) carbon dioxide (CO2) flux measurements in an Atlantic blanket bog in Ireland. The measured net ecosystem CO2 exchange (NEE) was partitioned into its components of ecosystem respiration (ER) and gross ecosystem production (GEP). The inter-annual variation of the CO2 fluxes was investigated using correlation coefficient analyses with measured hydro-meteorological parameters. The annual NEE was negative for all five years (thus the peatland was a sink of CO2), ranging between −16.5±5.1 and −96.5±23.2gC-CO2 m−2 (average of −54.9±15.6gC-CO2 m−2). During the study period, NEE was negative for the same five months in each year (May–September). NEE showed the highest CO2 uptake (due to the highest GEP) in the summer with intermediate rather than extreme meteorological conditions, thus with low vapour pressure deficit, intermediate soil water content, air temperature and light radiation, which might be partly explained by the role of the bryophyte community. Under climate change predictions of higher temperature, the inter-annual variation analysis suggests that ER might increase in winter. Furthermore, the predicted lower precipitation and higher temperature in the summer are expected to lead to lower GEP. The resulting increase in NEE (thus lower CO2 uptake) will be partly compensated by a higher GEP in warmer winters and in dryer autumns. Moreover, the CO2 uptake will benefit by a longer growing season, while wetter conditions will likely lower the ecosystem respiration in the spring. The length of the growing season was found to be driven by warmer winter and September soil temperatures. [Copyright &y& Elsevier]