Field intercomparison of throughfall measurements performed within the framework of the Pan European intensive monitoring program of EU/ICP Forest.
A 6-month field intercomparison study on throughfall measurements was performed at Speulder forest near the west coast in The Netherlands. Twenty throughfall sampling systems were evaluated on accuracy, sampling strategy and performance under field conditions. Throughfall fluxes of NO3-, K+ and Kjeldahl-N generally could be determined with a larger accuracy than fluxes of SO4(2-), NH4+, Na+, Cl-, Mg2+, Ca2+, and alkalinity. Throughfall fluxes of H+ generally had the lowest accuracy. Only 20% of the sampling systems differed more than 20% from the best estimate, whereas 45% of the systems stayed within a 10% range from the best estimate. The difference from the best estimate was mainly caused by aspects related to sampling strategy, like, for example, collecting area, sampler placement. The inaccuracy induced by the sampling system appeared to be much larger than that resulting from the analysis of the samples by different laboratory as determined by ring-tests. The field intercomparison described in this article gave a good insight in the different aspects contributing to the overall accuracy of the measurements. However, performing a future field intercomparison is recommended for throughfall and stemflow in order to also take in account other aspects that might influence the performance of the different measurement systems (e.g. tree species, climate zone, summer/winter period).
Bleeker
Albert
A
TNO Environment, Energy and Process Innovation, PO Box 342, 7300 AH, The, Apeldoorn, Netherlands. a.bleeker@mep.tno.nl
Draaijers
Geert
G
van der Veen
Dennis
D
Erisman
Jan Willem
JW
Möls
Han
H
Fonteijn
Peter
P
Geusebroek
Marco
M
D000393:Air Pollutants / Q000032:analysis*; D002980:Climate; D017753:Ecosystem; D004784:Environmental Monitoring / Q000295:instrumentation / Q000379:methods* / Q000592:standards; D007391:International Cooperation; D009426:Netherlands; D015203:Reproducibility of Results; D014197:Trees
D000393:Air Pollutants