The decline in plant biodiversity slows down soil carbon turnover under increasing nitrogen deposition in a temperate steppe
The decline in plant biodiversity slows down soil carbon turnover under increasing nitrogen deposition in a temperate steppe
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在温带草原氮沉降增加的情况下，植物生物多样性的下降减缓了土壤碳周转
DOI：
10.1111/1365-2435.13338
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发表时间：
2019
影响因子：
5.2
通讯作者：
Lingli Liu
中科院分区：
文献类型：
--
作者：
Sen Yang;Weixing Liu;Chunlian Qiao;Jing Wang;Meifeng Deng;Beibei Zhang;Lingli Liu
氮沉降不仅改变了植物个体的生理过程，而且导致全球生物多样性的丧失。然而，人们对植物群落结构对个体生理过程的分级响应如何对土壤碳循环产生级联效应知之甚少。我们评估了在增加N输入的情况下，植物化学组成和群落组成的变化是否会影响凋落物层的周转速率和通过异养呼吸（Rh）的土壤C损失。结果表明，十年以上的施氮显著降低了植物物种丰富度、凋落物层周转率和Rh。13 C-NMR结果表明，对于单个物种，N的加入增加了不稳定的C基团如烷基和甲氧基的丰度，或减少了不稳定的C基团如碳水化合物，导致大多数物种的碳水化合物C-与-甲氧基C比（CC/MC）降低。随着氮沉降量的增加，易降解的优势种冰草和冷蒿的丰度迅速下降，难降解的优势种二叉委陵菜和赖草逐渐占优势。在群落水平上，物种化学组成和植物群落组成的变化显著降低了凋落物质量，表现为在较高的氮添加量下，群落水平的CC/MC较低。step-AIC模型选择的结果进一步表明，植物多样性的丧失和群落水平CC/MC的降低共同解释了氮添加量的降低。进一步的相对重要性划分结果表明，这两个因子分别贡献了65.1%和34.9%的变异，总体而言，我们证明了由于氮添加引起的植物化学组成的变化和多样性损失降低了植物C输入土壤的质量，进一步减缓了枯落物层周转速率，抑制了土壤异养呼吸。本文的研究补充了全球变化下植物群落结构变化对土壤碳循环调控的中间环节，为本文提供了一个简明扼要的总结。
Nitrogen (N) deposition not only alters the physiological processes of individual plant, but also leads to world‐wide 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.Here, we assessed whether changes in plant chemical composition 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.We showed that more than a decade’s N addition significantly decreased plant species richness, litter layer turnover rate andRh. The13C‐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 asAgropyron cristatumandArtimesia frigidadeclined rapidly, and the relatively recalcitrant species such asPotentilla bifurcaandLeymus chinensisbecome dominant. Changes in individual species’ chemical composition 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.The result of step‐AIC model selection further showed that plant diversity loss and the decrease in community‐level CC/MC jointly explained the decrease inRhafter N addition best, and further relative importance partition result showed that these two factors respectively contributed 65.1% and 34.9% of the explained variation.Overall, we demonstrated that changes in plant chemical composition 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 regulate soil C cycle under global changes.A plain language summary is available for this article.