Response of leaf, sheath and stem nutrient resorption to 7 years of N addition in freshwater wetland of Northeast China
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Background and Aims
Increased N availability induced by agricultural fertilization applications and atmospheric N deposition may affect plant nutrient resorption in temperate wetlands. However, the relationship between nutrient resorption and N availability is still unclear, and most studies have focused on leaf nutrient resorption only. The aim of our study was to examine the response of leaf and non-leaf organ nutrient resorption to N enrichment in a temperate freshwater wetland.
We conducted a 7-year N addition experiment to investigate the effects of increased N loading on leaf, sheath and stem nutrient (N and P) resorption of two dominant species (Deyeuxia angustifolia and Glyceria spiculosa) in a freshwater marsh in the Sanjiang Plain, Northeast China.
Our results showed that, for both leaf and non-leaf organs (sheath and stem), N addition decreased N resorption proficiency and hence increased litter N concentration. Moreover, the magnitude of N addition effect on N resorption proficiency varied with fertilization rates for D. angustifolia sheaths and stems, and G. spiculosa leaves. However, increased N loading produced inconsistent impacts on N and P resorption efficiencies and P resorption proficiency, and the effects only varied with species and plant organs. In addition, N enrichment increased litter mass and altered litter allocation among leaf, sheath and stem.
Our results highlight that leaf and non-leaf organs respond differentially to N addition regarding N and P resorption efficiencies and P resorption proficiency, and also suggest that N enrichment in temperate freshwater wetlands would alter plant internal nutrient cycles and increase litter quality and quantity, and thus substantially influence ecosystem carbon and nutrient cycles.
KeywordsFertilization Litter quality Litter quantity Marsh Resorption efficiency Resorption proficiency
We thank the staff of the Sanjiang Experimental Station of Wetland Ecology for facilitating this study, Dr. Li-Hua Zhang, De-Yan Liu and Gui-Sheng Yang for the maintenance of the field experimental plots, and two anonymous referees, Alfonso Escudero and Ya-Lin Hu for their helpful comments on an earlier draft of this manuscript. This study was funded by National Natural Science Foundation of China (Nos. 40930527, 41103037 and 41125001), “Strategic Priority Research Program – Climate Change: Carbon Budget and Related Issue” of the Chinese Academy of Sciences (No. XDA05050508) and National Key Basic Research and Development Projects of China (No. 2009CB421103).
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