The carbon budget of terrestrial ecosystems at country-scale – a European case study

Abstract

Abstract. We summed estimates of the carbon balance of forests, grasslands, arable lands and peatlands to obtain country-specific estimates of the terrestrial carbon balance during the 1990s. Forests and grasslands were sinking carbon consistently, whereas arable soils were carbon sources in all European countries. Hence, countries dominated by arable lands tended to be losing carbon from their terrestrial ecosystems, whereas forest-dominated countries tended to be sinking carbon. In countries where peatlands are still being drained or extracted, net carbon balances were much lower than expected from land use. Net terrestrial carbon fluxes were typically small relative to fossil fuel-related carbon emissions. Only where fossil fluxes were small and net terrestrial fluxes were large did terrestrial carbon fluxes matter (ranged between uptake of 70% of fossil fluxes and increase of emissions with 25%). Nonetheless, at the European scale, the small net balance is composed of two very large but opposing fluxes: uptake by forests and grasslands and losses from arable lands and peatlands. Thus, relatively minor changes in either or both of these large component fluxes could strongly affect the net total, indicating that mitigation schemes should not be discarded a priori. In the absence of carbon-oriented land management, the current net carbon balance is bound to decline soon. Protecting it will require actions at three levels. Firstly, maintaining the current sink activity of forests. Secondly, altered agricultural management practices to turn arable soils into carbon sinks. Lastly, because carbon is lost more rapidly than sequestered, the current large reservoirs (wetlands and old forests) need extra protection.

How and where to map supply and demand of ecosystem services for policy-relevant outcomes?

“…Without a more detailed description of the methods used to score supply and demand, the scores themselves can be disputed. For example, the scores they assign for the service "global climate regulation" give the impression that LCC "broad-leaved forest" is in principle able to supply global climate regulation (score 4) at comparable levels to demand on LCC "road and rail networks" (also scored with 4), which is far from realistic (Janssens et al, 2005). In order to adequately compare supply and demand of ES more quantitative methods of scoring are needed.…”

Competing roles of rising CO<sub>2</sub> and climate change in the contemporary European carbon balance

“…On a local scale, Miglietta et al (2007) found that a European agricultural area could be a net source of carbon even in summer when growth might be expected to be greatest. Across Europe, Janssens et al (2005) found that crop lands are net annual sources of carbon whilst non-crop regions are carbon sinks. Meanwhile, expansion of European forest area, forestry management practices and nitrogen deposition are likely to create a substantial carbon sink (Janssens et al, 2005;Ciais et al, 2005b;Magnani et al, 2007).…”

“…Across Europe, Janssens et al (2005) found that crop lands are net annual sources of carbon whilst non-crop regions are carbon sinks. Meanwhile, expansion of European forest area, forestry management practices and nitrogen deposition are likely to create a substantial carbon sink (Janssens et al, 2005;Ciais et al, 2005b;Magnani et al, 2007). CO 2 fertilisation (Norby et al, 2005;Ciais et al, 2005b) and changes in long-term climate (Davi et al, 2006) will also affect European carbon storage.…”

Estimating economic value of site quality for uncertain ecosystem service provision in Swedish forests

“…There is a large body of literature on estimation of the forest carbon sink and effects of management practices (e.g. Janssens et al 2005;Helin et al 2013;Lundmark et al 2014). Carbon is stored in soil and aboveground biomass, but is released from clear cutting and wood products.…”