Davos Seehornwald - Switzerland

The forest site "Davos Seehornwald" has been installed in 2006 as part of the Swiss Long-term Forest Ecosystem Research Programme LWF. The programme investigates anthropogenic and natural forces on the long-term health of the forests and the potential risks to humans. For this, a profound understanding of the relationship between processes, causes and effects in the ecosystem are necessary. The objectives of the LWF research programme include (i) early detection and a representative assessment of changes in forest condition, (ii) determination of external influences, both from anthropogenic and natural sources such as element inputs and climate and their effect on the forest ecosystem, (iii) development of indicators to assess the condition of the forest, (iv) integrated risk assessment based on different stress scenarios, and (v) extended platform for internal and external research projects. The research site Davos Seehornwald offers a unique combination of ongoing long-term measurements of regional climate (since 1876), CO2 and microclimate profiles through the forest incl. soil temperatures and soil water potentials (since 1996), tree physiological records such as sap flow and continuous stem radius changes (since 1998), turbulent fluxes of CO2, H2O (since 1997) and CH4, N2O (since 2014) by eddy covariance, continuous atmospheric NO, NO2 and O3 concentrations (since 1991), aerosol concentrations (PM10) since 2017, and multiple properties of the vegetation (e.g. crown transparency, litter-fall, rain depositions) and soil structure (since 2004). Additionally, continuous gas-exchange of twigs was measured under ambient and increased CO2 concentrations from 1997 to 2005. The very long continuous track record of most measurements makes this research site to a predestined location for investigations about (missing) links between climate change and tree physiological adaptations and to a hot spot for addressing questions about the ecosystem carbon balance in relation to soil related components and tree physiological processes (under changing environmental conditions).