Different effect of drying on the fluxes of dissolved organic carbon and nitrogen from a Norway spruce forest floor
Different effect of drying on the fluxes of dissolved organic carbon and nitrogen from a Norway spruce forest floor
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DOI：
10.1002/1522-2624(200010)163:5
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发表时间：
2000-10
影响因子：
2.5
通讯作者：
A. Prechtel;C. Alewell;B. Michalzik;E. Matzner
中科院分区：
文献类型：
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作者：
A. Prechtel;C. Alewell;B. Michalzik;E. Matzner
森林地表是森林土壤溶解有机碳（DOC）和氮（DON）的主要来源。目前对DOC和DON的释放机制、环境控制以及浓度和通量的动态变化仍知之甚少。我们研究了干燥和再湿润对挪威云杉林地被DOC和DON释放的影响。从挪威云杉（Piceabies [L.]）林下地面采集直径17 cm、高15-20 cm的原状土柱，重复7次。喀斯特。）在10 ℃的实验室中建立。将色谱柱暴露于不同的干燥时间段（3、5、10、20天）。每个干燥期之后，在10 mm d（-1）的灌溉速率下，用自然穿透水溶液再润湿5天。每天采集森林地表水，分析DOC、总N、NH 4、NO3、pH、电导率和主要离子。干燥10和20天，Oi层的含水量从280%干重降低到约30%。Oe层和Oa层的含水量仅在300%~ 200%之间变化。干燥和复湿对森林地表DOC通量有一定影响，干燥3天和5天后，DOC通量增加，10天和20天后，DOC通量减少。相反，干燥10和20天导致DON通量的急剧增加和随后的DOC/DON比值从约50下降到3.3。这些结果表明，DOC释放在森林地面上的机制不同，从那些为DON和干燥和复湿引起的DOC/DON比值在森林地面的降水时间变化。
The forest floor represents the major source of dissolved organic carbon (DOC) and nitrogen (DON) in forest soils. The release mechanisms of DOC and DON from forest floors and their environmental controls as well as the dynamics of concentrations and fluxes are still poorly understood. We investigated the effect of drying and rewetting on the release of DOC and DON from a Norway spruce forest floor. Undisturbed soil columns of 17 cm diameter and 15-20 cm height were taken with 7 replicates from the forest floor of a mature Norway spruce (Picea abies [L.] Karst.) site and established at 10 degreesC in the laboratory. Columns were exposed to different periods of drying (3, 5, 10, 20 days). Each drying period was followed by a rewetting for 5 days at an irrigation rate of 10 mm d(-1) with a natural throughfall solution. The percolates from the forest floor were collected daily and analyzed for DOC, total N, NH4, NO3, pH, electrical conductivity and major ions. Drying for 10 and 20 days decreased the water content of the Oi horizon from 280% dry weight to about 30%. The water content of the Oe and the Oa horizon only changed from about 300% to 200%. The fluxes of DOC from the forest floor were moderately effected by drying and rewetting with an increase after 3 and 5 days of drying, but a decrease after 10 and 20 days. On the contrary, the drying for 10 and 20 days resulted in a drastic increase of the DON fluxes and a subsequent decrease of the DOC/DON ratios in the forest floor percolates from about 50 to 3.3. These results suggest that the mechanisms for DOC release in forest floors differ from those for DON and that drying and rewetting cause temporal variations in the DOC/DON ratios in forest floor percolates.