The ExpeER call for Transnational Access (TA) proposals provides a unique opportunity for research teams and individuals to access some of Europe's major research infrastructures focused on ecosystem research. Each month, we will focus on one or two of these sites.

Focus on the Hyytiälä observational site (Finland)

Hyytiälä facilities

The SMEAR site (Station for Measuring Ecosystem-Atmosphere Relations) is situated in the Hyytiälä Forestry Field Station of the University of Helsinki. The site consists of a managed, 50-yr old Scots pine forest stand, two open oligotrophic fen sites and a humic lake with forested catchment. The main idea of SMEAR-type infrastructures is continuous, comprehensive measurements of fluxes, storages and concentrations in the land ecosystem–atmosphere continuum. The forest measurements are operated continuously since 1996, and include e.g. leaf, stand and ecosystem scale measurements of greenhouse gases, volatile organic compounds, pollutants (e.g. O3, SO2, NOx) and aerosols, in addition to full suite of meteorological measurements. The biogeochemical cycles and vegetation – soil – atmosphere interactions are studied both experimentally and with long-term observations. The site has full carbon, water and nitrogen budgets made over 10 years, and it is a full ICOS ecosystem station.

• What are the new developments since the beginning of ExpeER?
"In summer 2012, 18 trenching plots were established in the pine stand, in order to analyze how plant input of recently assimilated carbohydrates to soil is linked to the decomposition soil organic matter and utilization soil organic nitrogen sources. Next summer we will start measurements of carbonyl sulfide (COS) fluxes in the forest, in order to obtain improved estimates of the magnitude and variability of ecosystem-scale photosynthesis, respiration and transpiration. The lake Eddy covariance measurements have been complemented with campaign wise turbulence, VOC and CH4 measurements. The nearby spruce swamp forest was drained in order to analyze the effect of water level on GHG fluxes and ecosystem carbon balance."

Possible theme for the TNA visits:

Our site welcomes research visits related to lake, soil and vegetation processes, e.g. C and N fluxes; production and emissions of VOCs and CH4; COS deposition; decomposition; and tree water relations.

• One project have been accepted so far:
- Measuring and modelling soil CO2 concentrations, production and diffusion (MMCO2). More

> Picture (Juho Aalto): Forest floor and soil measurements at SMEAR II station, e.g. automatic chamber for gas exchange, litter collectors and soil moisture content measuring setup.

Recent publications

AALTONEN, H., AALTO, J., KOLARI, P., PIHLATIE, M., PUMPANEN, J., KULMALA, M., NIKINMAA, E., VESALA, T. & BÄCK, J. (2012) Continuous VOC flux measurements on boreal forest floor. Plant and Soil DOI 10.1007/s11104-012-1553-4

BÄCK J., AALTO J., HENRIKSSON M., HAKOLA H., HE, Q. & BOY, M. (2012) Chemodiversity of a Scots pine stand and implications for terpene air concentrations. - Biogeosciences 9: 689–702.

KOLARI P., BÄCK J., TAIPALE R., RUUSKANEN T.M., KAJOS M.K., RINNE J., KULMALA M. & HARI P. (2012) Evaluation of accuracy in measurements of VOC emissions with dynamic chamber system. - Atmospheric Environment 62: 344-351

KORHONEN J.F-J, PIHLATIE M, PUMPANEN J., AALTONEN H., HARI, P., LEVULA, J., KIELOAHO, A.-J., NIKINMAA, E., VESALA, T. AND ILVESNIEMI, H. (2012) Nitrogen balance of a boreal Scots pine forest. Biogeosciences Discuss., 9, 11201-11237

KUUSINEN, N., KOLARI, P., LEVULA, J., PORCAR-CASTELL, A., STENBERG, P., & BERNINGER, F. (2012). Seasonal variation in boreal pine forest albedo and effects of canopy snow on forest reflectance. Agricultural and Forest Meteorology, 164, 53-60.

NIKINMAA E., HÖLTTÄ T., HARI P., KOLARI P., MÄKELÄ A. SEVANTO, S. & VESALA T. (2012). Assimilate transport in phloem sets conditions for leaf gas exchange. Plant, Cell & Environment DOI: 10.1111/pce.12004