Holger Lange
Seniorforsker
Forfattere
Adam Kristensson Paul Miller Holger Lange Thomas Holst Jaana Bäck Pontus Roldin Natascha Kljun Anne Klosterhalfen Anders Ahlström Thomas A. Pugh Liesbet Vranken Mark Rounsevell Svein Solberg James AtkinsonSammendrag
Forests are a key plank of European policies to mitigate and adapt to climate change and to promote biodiversity. These policies are starting to become more nuanced with respect to the account of their impacts on carbon storage, considering the effect of long-lived wood products and value of conserving old-growth forests, along with indirect land-use change impacts. However, a CO2-focused perspective means that many processes are still omitted for the quantification of the true extent of climate effects. Emissions of the greenhouse gases nitrous oxide and methane, short-lived climate forcers and effects from albedo changes and heat fluxes are also relevant. These processes are interconnected and influence the climate mitigation of forests in a complex way and need to be considered. The CLImate Mitigation and Bioeconomy pathways for sustainable FORESTry (CLIMB-FOREST) Horizon Europe project that runs until 2027 uses a holistic approach to estimate the climate impacts of various management alternatives. The foundation of CLIMB-FOREST is the use of European-wide empirical data, as well as an advanced coupled vegetation and earth-system modelling framework that includes biodiversity indicators and the interaction of forestry stakeholders in a global trade system. This framework is used to model management, forest tree species and climate on short- to long-term in Europe. We present first results of the climate effects and ecosystem functioning for a range of management alternatives in boreal, temperate, and Mediterranean forests. For example, introducing broadleaved trees in a coniferous forest promotes resilience and increased cooling from higher solar light scattering and latent heat flux of broadleaved trees. On the other hand, higher evapotranspiration might lead to an accelerated soil moisture depletion and reduced monoterpene emissions. The latter would have a warming effect because terpenes produce atmospheric particles, which are effective cooling agents through their involvement in cloud formation. Consequently, understanding these complex climate effects is key for appropriate climate-smart-forestry policies and approaches. The main outcomes and impacts of CLIMB-FOREST are to suggest alternative pathways for the forest sector to mitigate climate change in entire Europe, create attitude change in the policymaking process and influence foresters to adopt to new forest management strategies.
Forfattere
Carl-Fredrik Johannesson Klaus Steenberg Larsen Hanna Marika Silvennoinen Holger Lange Jenni NordénSammendrag
Det er ikke registrert sammendrag
Forfattere
Carl-Fredrik Johannesson Jenni Nordén Holger Lange Hanna Marika Silvennoinen Klaus Steenberg LarsenSammendrag
Non-steady-state chambers are often used for greenhouse gas flux measurements, and while there are recommendations on how long to keep the chamber closed, it is less investigated to what extent the length of the chamber closure period affects the estimated flux rates and which closure periods may provide the most accurate linear and non-linear flux estimates. Previous studies have shown that the closure of non-steady-state chambers induces a non-linear concentration development inside the chamber, even across short chamber closure periods, and that both linear and non-linear flux estimates are impacted by the chamber closure period itself. Based on 3,159 individual soil CO2 and CH4 flux measurements, we analyzed how linear regression and Hutchinson and Mosier (1981) modeled flux estimates are affected by the length of the chamber closure period by increasing it in increments of 30 sec, with a minimum and maximum chamber closure period of 60 and 300 sec, respectively. Across all detected flux measurements, the effect of chamber closure period length varied between 1.4–8.0 % for linear regression estimates and between 0.4–17.8 % for Hutchinson–Mosier estimates, and the largest effect sizes were observed in high flux regions. While both linear regression and Hutchinson–Mosier based estimates decreased as the chamber closure period increased, we observed a clear convergence of flux estimates as shorter and longer chamber closure periods were used for linear regression and Hutchinson–Mosier based estimation, respectively. This suggests using closure periods as short as possible for linear regression flux estimation or ensuring long-enough closure periods to observe a stabilization of Hutchinson–Mosier flux estimates over time. This analysis was based on soil flux measurements, but because the perturbation of the concentration gradient is related to the non-steady-state chamber technique rather than the measured ecosystem component, our results have implications for all flux measurements conducted with non-steady-state chambers.