Global change belowground: impacts of elevated CO2, nitrogen, and summer drought on soil food webs and biodiversity
Global change belowground: impacts of elevated CO2, nitrogen, and summer drought on soil food webs and biodiversity
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DOI：
10.1111/j.1365-2486.2011.02555.x
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发表时间：
2012-02-01
影响因子：
11.6
通讯作者：
Reich, Peter B.
中科院分区：
文献类型：
--
作者：
Eisenhauer, Nico;Cesarz, Simone;Reich, Peter B.
世界生态系统受到各种人为的全球变化因素的影响，例如大气中二氧化碳浓度的增加、氮(N)的沉积和降水制度的变化。尽管越来越多的人认识到，如果同时研究各种因素，可以更好地了解即将发生的全球变化的后果，但缺乏多因素的长期研究，特别是关于地下过程的研究。在这里，我们通过在美国明尼苏达州雪松溪的一项长期草原研究(Biocon实验)中检查土壤食物网和生物多样性对二氧化碳增加、氮升高和夏季干旱的响应来解决这个问题。我们使用结构方程模型(SEM)，各种非生物和生物解释变量，以及土壤微生物、原生动物、线虫和土壤微节肢动物的数据，来识别多种全球变化效应对地下驱动因素的影响。我们发现，CO2和N有效性的长期(13年)变化通过几种机制导致土壤生物食物网和生物多样性的轻微变化，包括土壤水分有效性、植物生产力，最重要的是根际沉积的变化。四年的夏季干旱只对地下食草动物和原生纤毛虫产生了不利的影响，在N升高的情况下，影响小得惊人。CO2升高增加了微生物生物量和纤毛虫、微型节肢动物有害动物和革螨的密度，这很可能是通过向土壤食物网添加不稳定的C来实现的。此外，CO2升高的有利自下而上效应抵消了N升高对土壤微型节肢动物类群丰富度的不利影响。相反，线虫类群丰富度在CO2和N升高时最低，因此，大气CO2浓度和N沉降的增加可能导致分类和功能上的改变，潜在地简化了土壤群落。氮沉积对土壤生物多样性的不利影响强调了最近关于植物群落简化的报告。这一点特别令人担忧，因为土壤拥有全球生物多样性和生态系统功能的相当大一部分。
The world's ecosystems are subjected to various anthropogenic global change agents, such as enrichment of atmospheric CO2 concentrations, nitrogen (N) deposition, and changes in precipitation regimes. Despite the increasing appreciation that the consequences of impending global change can be better understood if varying agents are studied in concert, there is a paucity of multi-factor long-term studies, particularly on belowground processes. Herein, we address this gap by examining the responses of soil food webs and biodiversity to enrichment of CO2, elevated N, and summer drought in a long-term grassland study at Cedar Creek, Minnesota, USA (BioCON experiment). We use structural equation modeling (SEM), various abiotic and biotic explanatory variables, and data on soil microorganisms, protozoa, nematodes, and soil microarthropods to identify the impacts of multiple global change effects on drivers belowground. We found that long-term (13-year) changes in CO2 and N availability resulted in modest alterations of soil biotic food webs and biodiversity via several mechanisms, encompassing soil water availability, plant productivity, and most importantly changes in rhizodeposition. Four years of manipulation of summer drought exerted surprisingly minor effects, only detrimentally affecting belowground herbivores and ciliate protists at elevated N. Elevated CO2 increased microbial biomass and the density of ciliates, microarthropod detritivores, and gamasid mites, most likely by fueling soil food webs with labile C. Moreover, beneficial bottom-up effects of elevated CO2 compensated for detrimental elevated N effects on soil microarthropod taxa richness. In contrast, nematode taxa richness was lowest at elevated CO2 and elevated N. Thus, enrichment of atmospheric CO2 concentrations and N deposition may result in taxonomically and functionally altered, potentially simplified, soil communities. Detrimental effects of N deposition on soil biodiversity underscore recent reports on plant community simplification. This is of particular concern, as soils house a considerable fraction of global biodiversity and ecosystem functions.