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Title:
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Final report of the project input-output relationships for intensive monitoring sites
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Author(s):
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Erisman, J.W.; Vermeulen, A.T.; Vries, W. de; Salm, C. van der; Reinds, G.J.; Draaijers, G.P.J.; Bleeker, A.; Lakkenborg Kristensen, H.; Gundersen, P.
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Published by:
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Publication date:
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ECN
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1-7-2002
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ECN report number:
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Document type:
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ECN-C--02-066
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ECN publication
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Number of pages:
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Full text:
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134
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Download PDF
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Abstract:
This report describes the work done within the project "Input - outputrelationships for Intensive Monitoring sites", EC contract number SG(99)
D/10844. The project results are extensively reported in the Technical
Report 2000 (De Vries et al., 2001). Input estimates for selected Level
II plots are obtained from throughfall measurements corrected for canopy
exchange. Output fluxes were obtained using hydrological model output
combined with soil concentrations. Leaching fluxes and input estimates
provided the balances. Mean yearly interception evaporation ranged from
approximately 160 mm for Pine and Oak to approximately 250 mm for Beech
and 300 mm for Spruce, reflecting the increasing interception capacity
of those tree species. Median transpiration fluxes were rather constant
among the tree species and ranged from 325 mm.yr-1 for Pine
to 385 mm.yr-1 for Spruce stands. At most plots, the leaching
flux of SO4 is higher than that of NO3, despite
the generally lower input of S than of N, indicating that SO4
is still the dominant source of actual soil acidification. The median
sulphur budget is close to zero, but at a considerable number of sites,
sulphur is released by the soil, indicating that these systems are recovering
from previous episodes of high sulphate input. The leaching of N is
generally negligible below throughfall inputs of 10 kg.ha-1.yr-1.
There is a significant relationship between N leaching and N deposition
but no significant relationship was found with the soil C/N ratio. Nitrogen
budgets show that at most sites (90%) the N input is higher then the
N leaching. Variations in base cations leaching were significantly related
to the S input and the pH and base saturation. The median base cation
balance is close to zero,
implying a net adsorption and a net release of base cations at approximately
50% of the plots. The Al leaching flux was significantly related to
the SO4 input reflected by the fact that sites with a high
Al leaching coincide with sites with a high input of SO4.
The geographic patterns of both elements, however, did not coincide
very well since soil base saturation was also significantly related
to the Al leaching flux.
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