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Data from: The decline in plant biodiversity slows down soil carbon turnover under increasing nitrogen deposition in a temperate steppe

Citation

Yang, Sen et al. (2019), Data from: The decline in plant biodiversity slows down soil carbon turnover under increasing nitrogen deposition in a temperate steppe, Dryad, Dataset, https://doi.org/10.5061/dryad.kn92b41

Abstract

1. Nitrogen (N) deposition not only alters the physiological processes of individual plant, but also leads to worldwide biodiversity loss. However, little is known about how the hierarchical responses from individual physiological processes to plant community structure would have cascading effects on soil carbon (C) cycling. 2. Here, we assessed whether changes in plant chemistry and community composition under increasing N input would affect the turnover rate of litter layer and soil C loss via heterotrophic respiration (Rh) in a temperate grassland. 3. We showed that more than a decade’s N addition significantly decreased plant species richness, litter layer turnover rate and Rh. The 13C-NMR results showed that, for individual species, N addition either increased the abundance of recalcitrant C groups such as Alkyl and Methoxyl, or decreased labile C groups such as Carbohydrate, resulting in decreases in Carbohydrate C to Methoxyl C ratio (CC/MC) for most species. Our data also showed that with the increase in N deposition, the abundance of relatively high degradable dominant species, such as A. cristatum and A. frigida declined rapidly, and the relatively recalcitrant species such as P. bifurca and L. chinensis become dominate. Changes in individual species’ chemistry and plant community composition significantly decreased litter quality at community level, as indicated by the lower community level CC/MC at higher N addition rates. 4. The result of step-AIC model selection further found that plant diversity loss and the decrease in community level CC/MC jointly best explained the decrease in Rh after N addition, and further relative importance partition result showed that these two factors respectively contributed 65.1% and 34.9% of the explained variation. 5. Overall, we demonstrated that changes in plant chemistry and diversity loss due to N addition reduced the quality of plant C input to soil, which further slowed down litter layer turnover rate and inhibited soil heterotrophic respiration. Our study complements the intermediate links of how shifts in plant community structure regulates soil C cycle under global changes.

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