Henning Meesenburg (email@example.com) &
Karl J. Meiwes (firstname.lastname@example.org)
Forest Experiment Station of Lower Saxony, Grätzelstr. 2, D-37079, Göttingen, Germany.
A liming experiment with an ameliorative dosage was conducted in 1989 in the forested catchment Steile Bramke. The catchment (38 ha) is situated in the Harz Mountains (Germany) at an elevation of 510 to 670 m a.s.l. and is covered by a Norway spruce (Picea abies) stand with an average age of 113 years. The bedrock is Lower Devonian quartzitic sandstone overlain by podzolic soils with a high content of stones. The hydrological system is characterized by deep vertical infiltration up to 2 m in depth.
The lime requirement was calculated according to the base neutralisation capacity (BNC, at pH 5) of the soil up to 40 cm depth. Sixteen t ha-1 of granulated dolomite was applied by helicopter. Soil solution was collected before liming, in the initial period after liming, and 4 years after liming. Stream water has been monitored since 1987 in the limed catchment and in a reference catchment. The nutritional status of the trees was evaluated before and 4 years after liming.
Soil solution chemistry responded to the liming with initial rise in concentrations of most elements. Contents of calcium (Ca) and magnesium (Mg) in soil solution generally increased after liming. During the initial period after liming, high contents of mobile ions like sulphate (SO42-) and nitrate (NO3), which were accompanied by high concentrations of Ca, Mg, and other cations, were measured. The most pronounced effects on pH and acid neutralising capacity (ANC) occurred 4 years after liming. Up to 40 cm depth, ANC shifted from negative values before liming to positive ones. Nitrate concentrations in soil solution increased in the initial period after liming and decreased below pre-liming values since then. Ca/Al ratios generally increased after liming. Up to 20 cm depth, Ca-Al ratios were greater than 1 mol/mol, indicating that stress for tree roots was reduced due to liming.
Streamwater at the outflow from the catchment usually is well buffered at low flows, but episodic acidification occasionally occurs during high flows. Influences of liming on streamwater chemistry were not very pronounced. An increase in NO3- concentrations, which is often suspected to occur, did not occur. This led to the conclusion that a risk of increased nitrogen (N) losses after liming is small even with high doses of lime. On the other hand, an influence on streamwater pH and ANC was only slightly visible for high flow situations. Concentrations of Ca and Mg decreased significantly in the reference catchment, whereas no trend was detectable at Steile Bramke indicating a possible effect of liming.
The nutritional status of the spruce stand was clearly improved after liming as compared to 1988 and to the reference stand. A Mg-deficiency, which was present in 1988, diminished after liming. Contents of Ca, N and phosphorus (P) in the needles also increased after liming.
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