bei Google ScholarTitelangaben
Chen, Yao-Te ; Bogner, Christina ; Borken, Werner ; Stange, Claus Florian ; Matzner, Egbert:
Minor response of gross N turnover and N leaching to drying, rewetting and irrigation in the topsoil of a Norway spruce forest.
In: European Journal of Soil Science.
Bd. 62
(2011)
Heft 5
.
- S. 709-717.
ISSN 1351-0754
DOI: https://doi.org/10.1111/j.1365-2389.2011.01388.x
Abstract
Forest floors in the temperate climate zone are frequently subjected to strong changes in soil moisture, but theconsequences for the soil N cycle are poorly known. In a field experiment we tested the hypotheses that soildrying leads to a decrease of gross N turnover and that natural rewetting causes a pulse of gross N turnoverand an increase of N leaching from the forest floor. A further hypothesis was that optimal water availabilityinduced by irrigation causes maximum N turnover and N leaching. Replicated control, throughfall exclusionand irrigation plots were established in a Norway spruce forest to simulate different precipitation patternsduring a growing season. Gross N turnover rates were determined in undisturbed soil cores from Oi + Oeand Oa + EA horizons by the 15N pool dilution technique. Forest floor percolates were periodically collectedby suction plates.After 142 mm throughfall was excluded, the median soil water potential at the throughfall exclusion plotsincreased from pF 1.9 to 4.5 in the Oi + Oe horizon and from pF 1.8 to 3.8 in the Oa + EA horizon.Gross ammonification ranged from 14 to 45 mg N kg−1 soil day−1 in the Oi + Oe horizon and from 4.6 to11.4 mg N kg−1 soil day−1 in the Oa + EA horizon. Gross ammonification of both horizons was smallestin the throughfall exclusion plots during the manipulation, but the differences between all treatments werenot statistically significant. Gross nitrification in both horizons was very small, ranging from 1.6 to 11.1mg N kg−1 soil day−1. No effects of decreasing water potential and rewetting on gross nitrification rates wereobserved because of the small rates and huge spatial variations. Irrigation had no effect as the differencesfrom the control in soil water potential remained small. N leaching from the forest floor was not affected bythe treatments. Our findings suggest that ammonification in forest floors continues at considerable rates evenat small water potentials. The hypotheses of increased N turnover and N leaching following rewetting of dryforest floor or irrigation were not confirmed.