Neutron radiography as a tool for revealing root development in soil: capabilities and limitations |
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Authors: | Moradi Ahmad B Conesa Héctor M Robinson Brett Lehmann Eberhard Kuehne Guido Kaestner Anders Oswald Sascha Schulin Rainer |
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Institution: | 1. Institute of Geographical Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, 100101, People’s Republic of China 4. 11A, Datun Road, Beijing, 100101, People’s Republic of China 2. Graduate University of Chinese Academy of Sciences, Beijing, 100049, People’s Republic of China 3. South China Botanic Garden, Chinese Academy of Sciences, Guangzhou, 510650, People’s Republic of China
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Abstract: | Chronic atmospheric nitrogen deposition affects the cycling of carbon (C) and nitrogen (N) in forest ecosystems, and thereby alters the stable C isotopic abundance of plant and soil. Three successional stages, disturbed, rehabilitated and mature forests were studied for their responses to different nitrogen input levels. N-addition manipulative experiments were conducted at low, medium and high N levels. To study the responses of C cycling to N addition, the C concentration and 13C natural abundances for leaf, litter and soil were measured. Labile organic carbon fractions in mineral soils were measured to quantify the dynamics of soil organic C (SOC). Results showed that three-year continuous N addition did not significantly increase foliar C and N concentration, but decreased C/N ratio and enriched 13C in N-rich forests. In addition, N addition significantly decreased microbial biomass C, and increased water soluble organic C in surface soils of N-rich forests. This study suggests that N addition enhances the water consumption per unit C assimilation of dominant plant species, restricts SOC turnover in N-poor forests at early and medium successional stages (thus favored SOC sequestration), and vice versa for N-rich mature forests. |
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