Soil microbial community structure is unaltered by plant invasion, vegetation clipping, and nitrogen fertilization in experimental semi-arid grasslands.
Soil microbial community structure is unaltered by plant invasion, vegetation clipping, and nitrogen fertilization in experimental semi-arid grasslands.
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DOI：
10.3389/fmicb.2015.00466
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发表时间：
2015
影响因子：
5.2
通讯作者：
Hart SC
中科院分区：
文献类型：
--
作者：
Carey CJ;Beman JM;Eviner VT;Malmstrom CM;Hart SC
全球和区域环境变化经常同时发生，对景观造成复杂的干扰梯度。土壤微生物群落是生态系统对环境变化响应的重要组成部分，但人们对微生物结构和功能如何响应多种干扰，或者多种环境变化是否会导致意想不到的相互作用效应知之甚少。我们的研究使用地中海气候下的半干旱草原试验地来确定季节性变化的生态系统中的土壤微生物群落如何响应一种、两种或三种同时发生的环境变化：外来植物入侵、植物入侵+植被修剪（模拟割草或牲畜放牧等常见管理实践）、植物入侵+氮（N）施肥以及植物入侵+修剪+氮施肥。我们通过对超过 100 万个 16S rRNA 基因进行测序，检查了样地建立 5-6 年后的微生物群落结构。还测量了非生物土壤特性（土壤湿度、温度、pH 和无机氮）和微生物功能（硝化和反硝化潜力），并显示了处理引起的变化，包括 NO−3 有效性、温度和硝化潜力的改变。尽管有这些变化，细菌和古菌群落在不同处理方法中的组成和多样性几乎没有变化。即使暴露于三种相互作用的环境变化的地块中的社区也与恢复的原生草原地块中的社区相似。除了先前的场地耕作之外，关键土壤特性的历史暴露于大的季节性和年际变化，可能会选择功能可塑或很大程度上休眠的微生物群落，从而形成在结构上对单一和多重环境变化具有鲁棒性的微生物群落。
Global and regional environmental changes often co-occur, creating complex gradients of disturbance on the landscape. Soil microbial communities are an important component of ecosystem response to environmental change, yet little is known about how microbial structure and function respond to multiple disturbances, or whether multiple environmental changes lead to unanticipated interactive effects. Our study used experimental semi-arid grassland plots in a Mediterranean-climate to determine how soil microbial communities in a seasonally variable ecosystem respond to one, two, or three simultaneous environmental changes: exotic plant invasion, plant invasion + vegetation clipping (to simulate common management practices like mowing or livestock grazing), plant invasion + nitrogen (N) fertilization, and plant invasion + clipping + N fertilization. We examined microbial community structure 5–6 years after plot establishment via sequencing of >1 million 16S rRNA genes. Abiotic soil properties (soil moisture, temperature, pH, and inorganic N) and microbial functioning (nitrification and denitrification potentials) were also measured and showed treatment-induced shifts, including altered NO−3 availability, temperature, and nitrification potential. Despite these changes, bacterial and archaeal communities showed little variation in composition and diversity across treatments. Even communities in plots exposed to three interacting environmental changes were similar to those in restored native grassland plots. Historical exposure to large seasonal and inter-annual variations in key soil properties, in addition to prior site cultivation, may select for a functionally plastic or largely dormant microbial community, resulting in a microbial community that is structurally robust to single and multiple environmental changes.