Decoupling of soil microbes and plants with increasing anthropogenic nitrogen inputs in a temperate steppe
Decoupling of soil microbes and plants with increasing anthropogenic nitrogen inputs in a temperate steppe
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温带草原中土壤微生物和植物与人为氮输入增加的脱钩
DOI：
10.1016/j.soilbio.2014.01.022
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发表时间：
2014-05-01
影响因子：
9.7
通讯作者：
Wan, Shiqiang
中科院分区：
文献类型：
--
作者：
Liu, Weixing;Jiang, Lin;Wan, Shiqiang
植物生长与土壤微生物活性有着内在的联系。大量证据表明，氮（N）沉积可以大大改变这两个过程。然而，氮沉降引起的这种变化是否会在植物和土壤微生物之间产生新的动力学尚不清楚。本研究试图探讨沿着氮添加梯度的植物微生物关系。从2003年开始，在中国北方温带草原上，每年设置8个施氮水平（0、1、2、4、8、16、32、64 gNm（-2））。从2005年到2007年收集了植物和土壤样本。结果表明，施氮对土壤酸化有显著影响。植物地上生物量和溶解性有机碳（DOC）都随着N输入的增加而增加。土壤微生物量碳、微生物量氮和微生物呼吸对氮素输入呈非线性响应。低水平的N输入刺激MBC，MBN和微生物呼吸，而高水平的N输入抑制它们。虽然MBC和MBN都与地上生物量在每个水平的N处理呈正相关，这种生物量对MBC和MBN的依赖性随着N添加量的增加而下降，如指数下降所示。地上生物量和MBC之间的联系减弱主要是由于土壤酸化。土壤pH值的下降引起的N输入增加减少土壤微生物活性，但不是植物生长。结果表明，随着氮素输入量的增加，植物与微生物的关系呈现出由耦合向解耦的趋势。植物和土壤微生物活性对增施氮肥的不同反应可能对生态系统功能和服务功能产生影响。(C)2014爱思唯尔有限公司版权所有。
Plant growth and soil microbial activity are intrinsically correlated. Numerous evidence shows that nitrogen (N) deposition can greatly alter both processes. However, it is unknown whether such changes caused by N deposition can create new dynamics between plants and soil microbes. This study was conducted with an attempt to examine the plant microbe relationship along an N addition gradient. Eight levels of N addition (0,1, 2, 4, 8,16, 32, 64 g N m(-2)) were applied annually in a temperate steppe in northern China since 2003. Plant and soil samples were collected from 2005 to 2007. We found that N addition acidified soil significantly. Both plant aboveground biomass and dissolved organic carbon (DOC) increased with increasing N input. However, soil microbial biomass carbon (MBC), microbial biomass nitrogen (MBN) and (soil) microbial respiration showed nonlinear responses to N input. Low levels of N inputs stimulated MBC, MBN and microbial respiration, whereas high levels of N input suppressed them. Although MBC and MBN were both positively correlated with aboveground biomass at each level of N treatments, the dependence of such biomass on MBC and MBN declined with the increase in N addition, as indicated by the exponential decreases in the regression coefficients. The weakened linkage between aboveground biomass and MBC was mostly attributed to soil acidification. The decrease in soil pH caused by elevated N inputs reduced soil microbial activities, but not plant growth. Overall, our results revealed a trend of shifting plant microbe relationship from coupling to decoupling with the increase of N input. The divergent responses of plants and soil microbial activities under intensified N addition could have consequent impacts on ecosystem function and services. (C) 2014 Elsevier Ltd. All rights reserved.