Netherlands Environmental Assessment Agency

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1 Page 116 of 171 HUNGARY National Focal Centre Miklós Dombos, László Pásztor, József Szabó Research Institute for Soil Science and Agricultural Chemistry Hungarian Academy of Sciences 122 Budapest Herman Ottó u. 15 tel: fax: Introduction Critical loads for the Hungarian forest ecosystems have been updated in 3. The database provided in 3 has been derived from the AGROTOPO soil database and the CORINE Land Cover database linked to additional information on spatial distribution of forests. To improve critical load modelling further database has been involved. The Hungarian Soil Monitoring Database (TIM) used in last year fulfilled the requirements of input parameters of the models (e.g. MakeDep, SAFE). However results of modelling have to be tested further thus critical data for acidification provided in 4 are still valid until the next call. Data sources Soil Information and monitoring system (TIM). Based on physiographical-soil-ecological units 1236 representative observation points were selected of which 183 sites are in forests. Monitoring was in 1992, measurements are repeated 1, 3 or 6 years depending on the stability of soil variables. Most of the soil parameters in the model have been gathered from measured data (Table HU-1). Biomass variables were derived from ICP sites (nutrient content) except the actual biomass, which was measured in sites (estimated from standing biomass classes) (Table HU-2). Mineralogical data was gathered from a mineralogical map. This is the weakest point of the data acquisition, because of the spatial resolution and the method of the estimation of mineral composition (Table HU-3). Results Cumulative distributions of some input parameters have been showed in figure HU-1. Values of these parameters are measured or estimated at sites. Histogram of base saturation differs significantly from dataset used in last years having a lower range. In Figure HU-2 time series of modelled response variables, like ph, base saturation and Bc:Al ratios have been illustrated in one site as an example. These curves are produced in all calibrated sites. Figure HU-3 shows the results of critical load modelling. The most inner points show the exceedance of critical loads; red points correspond to the occurrence of an exceedance, sites with blue points are not exceedance and grey points indicate that the calibration failed. The outside circles show the base saturation and ph in the three soil layers. An earlier assessment of the soil acidification is illustrated in the background of the maps, showing the susceptibility of soil acidification in ordinal scale. Red and brawn patches are higher susceptibility to acidification, whereas blue patches are calcareous soils. Conclusions: Hungarian soil monitoring database fulfilled the input requirements of MakeDep/SAFE models.

2 Page 117 of forest sites were enough to characterize the spatial heterogeneity of soil acidification status in country scale. Calibration failed at several sites that are to be checked later on. In many sites the results of the earlier soil susceptibility map and the critical load exceedances were consistent although output inconsistencies occurred at several sites. This might be explained by the nutrient nitrogen exceedances that are in the focus of the next modelling goals. Table HU-1. Soil parameters of the SAFE model. Soil parameters layers 3 layers according to the soil genetic classification layer thickness Evaporation fraction.2 Lateral flow not estimated rel Bc uptake Derived according to measured Bc concentrations in layer solution rel N uptake Derived according to measured NO3 conc. in layer solution soil bulk density soil moisture content According to the potential plant available soil moisture content /measured values of pf=4.2-pf=2.5/ mineral surface area Derived from particle size distribution (Xi) that are measured at sites Mineral surface area =.3*Xsand+2.2*Xsilt +6*Xclay)*Bulk density*1 cation exchange capacity E Ca E Mg E K soil solution DOC Arbitrary according to layers: in A layer =, B = 5, C = 2 soil solution p CO2 Arbitrary according to layers: in A layer =2, B = 5, C = 1 Al solubility coefficient - SO 4 to H ratio - q SO 4 - p1 SO 4 - p2 SO 4 - field capacity - wilting point - Table HU-2. Biomass parameters of the SAFE model. Biomass parameters Stem mass Estimated by forest yield classes Branch and Canopy mass Estimated from measured values at ICP sites, derived according to tree species and the estimated stem biomass Mineralization rate.15 LF miner rate.95 Coniferous Deciduous ratio or 1 Deciduous litter fraction 1 Coniferous litter fraction.14 Growth func. N Growth func. K for stem Growth func. K for root - Growth func. K for bark - Growth func. K for branch Growth func. K for canopy.65 Ca, Mg, K, Na contents in stem, branch and canopy: in ICP sites, derived according to tree species

3 Page 118 of 171 Table HU-3. Clay mineral composition used in modelling. Mineral composition types 'K-Feldspar:' 'Plagioclase:' 'DutchClay:' 'Smektite:' 'Muscovite:' 'illite-1:' 'illite-2:' 'illite-3:' 'Mg-Chlorite:' 'illite-verm:' 'Biotite:' 'Verm-1:' 'Verm-2:' 'Verm-3:' Stem biomass at 143 forest sites Soil bulk density in 3 lay ers at 143 f orest sites Stem mass (kg/m 2 ) Soil bulk density (kg/m 3 ) layer Mineral surf ace area in 3 lay ers at 143 f orest sites Soil moisture content in 3 lay ers at 143 forest sites E6 1E6 2E6 3E6 4E6 5E6 6E6 7E6 8E6 Mineral surf ace area (m 2 /m 3 ) - -,5,,5,1,15,,25,3,35,4 Soil moisture content (m 3 /m 3 ) Cation exchange capacity in 3 layers at 143 forest sites Base saturation in 3 lay ers at 143 f orest sites E-4,,1,2,3,4,5,6 CEC mmolc/kg Base saturation (%) layer 1. layer 2. layer 3. Figure HU-1. Cumulative histograms of stem biomass, soil bulk density, mineral surface area, soil moisture content, cation exchange capacity, and base saturation.

4 Page 119 of 171 Modelled time series of ph in 3 layers of a monitoring site 5, Modelled time series of base saturation in 3 layers of a mo nitorin g site,4 4,8,35 ph 4,6 4,4 4,2 4, 3,8 Base saturation (%),3,25,,15,1,5, 3, y ear -, year Modelled time series of Bc/Al in 3 layers of a mo nitorin g site 45 4 weighted molar Bc Al ratio y ear Figure HU-2. Modelled time series of soil ph, base cation /Al ratios in soil solution and base saturation.

5 Page 1 of 171 Figure HU-3. Critical load exceedances in Hungarian Soil Monitoring forest sites calculated by the SAFE model.