Latest developments in the long-term monitoring of vegetation characteristics in the ICOS ecosystem network.

The Integrated Carbon Observation System (ICOS) is a pan-European Research Infrastructure with the goal to monitor the greenhouse gas balance of Europe. The terrestrial component of the infrastructure consists of a network of more than 100 flux towers that continuously measure the exchange of greenhouse gases between the atmosphere and the ecosystem by using the eddy covariance technique. To interpret these fluxes a whole suite of other parameters that describe the state of the vegetation are measured. The Ecosystem Thematic Center (ETC) is coordinating the ecosystem network providing assistance with instruments and methods, testing and developing new measurement techniques and associated processing algorithms; also ensuring a high level of data standardization, uncertainty analysis and database services in coordination with the ICOS Carbon Portal. This presentation will give a brief overview of the vegetation-related parameters that are measured within the ecosystem network following standard methods and discuss some new methods that have been tested and introduced. For example a campaign with Terrestrial Laser Scanning was performed at a subset of forest stations to examine the potential to estimate above ground biomass from the gathered point clouds. More recently, below-canopy PAR measurements were introduced at the forest stations to estimate Plant Area Index (PAI) in addition to estimates from Digital Hemispherical Photography. This new method shows to be less sensitive to specific light conditions, less labor intensive and has the advantage of creating continuous time series which will be very valuable for validation of remote sensing products. First results of a cross comparison between both methods at several ICOS stations will be shown and discussed during the presentation.