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标题：Plant and Microbial Uptake and Allocation of Organic and Inorganic Nitrogen Related to Plant Growth Forms and Soil Conditions at Two Subarctic Tundra Sites in Sweden
其他标题：Plant and Microbial Uptake and Allocation of Organic and Inorganic Nitrogen Related to Plant Growth Forms and Soil Conditions at Two Subarctic Tundra Sites in Sweden
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作者：Pernille Lærkedal Sorensen ; Karina Engelbrecht Clemmensen ; Anders Michelsen 等
期刊名称：Arctic, Antarctic, and Alpine Research
印刷版ISSN：1523-0430
电子版ISSN：1938-4246
出版年度：2008
卷号：40
期号：1
页码：171-180
DOI：10.1657/1523-0430(06-114)[SORENSEN]2.0.CO%3B2
摘要：In order to follow the uptake and allocation of N in different plant functional types and microbes in two tundra ecosystems differing in nutrient availability, we performed a 15 N-labeling experiment with three N forms and followed the partitioning of 15 N label among plants, microorganisms and soil organic matter. At both sites the deciduous dwarf shrub Betula nana and the evergreen Empetrum hermaphroditum absorbed added 15 N at rates in the order: NH 4 > NO 3 − > glycine, in contrast to the graminoid Carex species which took up added 15 N at rates in the order NO 3 − > NH 4 > glycine. Carex transported a high proportion of 15 N to aboveground parts, whereas the dwarf shrubs allocated most 15 N to underground storage. Enhanced 13 C in Betula nana roots represents the first field evidence of uptake of intact glycine by this important circumpolar plant. Plant and microbial uptake of label was complementary as plants took up more inorganic than organic N, while microbes preferred organic N. Microbes initially took up a large part of the added label, but over the following four weeks microbial 15 N decreased by 50% and most 15 N was recovered in soil organic matter, while a smaller but slowly increasing proportion was retained in plant biomass.