Preferential use of root litter compared to leaf litter by beech seedlings and soil microorganisms
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Background and aims
Litter decomposition is regulated by e.g. substrate quality and environmental factors, particularly water availability. The partitioning of nutrients released from litter between vegetation and soil microorganisms may, therefore, be affected by changing climate. This study aimed to elucidate the impact of litter type and drought on the fate of litter-derived N in beech seedlings and soil microbes.
We quantified 15N recovery rates in plant and soil N pools by adding 15N-labelled leaf and/or root litter under controlled conditions.
Root litter was favoured over leaf litter for N acquisition by beech seedlings and soil microorganisms. Drought reduced 15N recovery from litter in seedlings thereby affecting root N nutrition. 15N accumulated in seedlings in different sinks depending on litter type.
Root turnover appears to influence (a) N availability in the soil for plants and soil microbes and (b) N acquisition and retention despite a presumably extremely dynamic turnover of microbial biomass. Compared to soil microorganisms, beech seedlings represent a very minor short-term N sink, despite a potentially high N residence time. Furthermore, soil microbes constitute a significant N pool that can be released in the long term and, thus, may become available for N nutrition of plants.
KeywordsLitter types Root litter Leaf litter Decomposition Microbial biomass Plant N metabolism Soil N pools 15N recovery
This work was funded by the German Research Foundation / Deutsche Forschungsgemeinschaft (DFG) within the framework of the Beech Research Group under contract numbers FOR 788/1, RE 515/27-1, PO 362/17-1, and DA 1217/2-1. C.G. was financially supported by a scholarship from the China Scholarship Council (no. 2007U27036). Judy Simon was financially supported by the European Social Fund and by the Ministry of Science, Research and the Arts Baden-Württemberg. Furthermore, we thank Merle Fastenrath, Regina Wiegel and Elisabeth Zumbusch for expert assistance during the experiment.
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