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Frequent Fire Reduces the Magnitude of Positive Interactions Between an Invasive Grass and Soil Microbes in Temperate Forests
Ecosystems ( IF 3.7 ) Pub Date : 2021-02-25 , DOI: 10.1007/s10021-021-00615-x
Jennifer M. Fraterrigo , Mara K. Rembelski

Fire activity is increasing in many regions. Although increased fire activity is expected to promote plant invasion, over longer time periods, frequent fire can shift the nutrient status of ecosystems, which may alter interactions between invasive plants and soil microbial decomposers. Here, we applied a fire treatment to plots embedded in deciduous forests under regimes of either fire exclusion or frequent fire and invaded by the most widespread invasive grass in the eastern USA (Microstegium vimineum) to determine how frequent fire affects plant–soil interactions while controlling for time after fire. We predicted that frequent fire would increase microbial nitrogen (N) limitation, leading to lower Microstegium productivity and reduced soil carbon (C) and N loss. We found that Microstegium leaf, root, and microbial biomass C/N ratios were significantly wider under frequent fire than fire exclusion. Consistent with these patterns, dissolved organic N concentration was 22% lower and the activity of an exoenzyme targeting N acquisition was 59% higher under frequent fire, indicating that frequent fire increased microbial N limitation. Higher surface soil C and N and fire-induced increases in particulate soil organic matter N suggest that frequent fire in these grass-invaded forests enhanced microbial N limitation through the accumulation of microbially resistant pyrogenic N. A structural equation model confirmed that these changes were interrelated and associated with 87% lower Microstegium aboveground biomass and 85% higher fine root biomass. These findings provide new insights into how frequent fire impacts plant–soil microbial interactions and thus may feedback to plant invasion over longer time periods.



中文翻译:

频繁的火灾减少了温带森林中入侵性草丛与土壤微生物之间的正向相互作用

许多地区的火灾活动正在增加。尽管预计增加的火势活动会促进植物入侵,但在较长的时期内,频繁的火势可改变生态系统的营养状况,这可能会改变入侵的植物与土壤微生物分解剂之间的相互作用。在这里,我们对火灾隐患或频繁火灾并被美国东部传播最广泛的入侵性草(Microstegium v​​imineum)入侵的落叶林中的地块进行了火灾处理,以确定频繁火灾如何在控制植物的同时影响植物与土壤的相互作用在大火后的时间。我们预测,频繁火灾会增加微生物氮(N)的限制,从而导致较低的生产率并减少土壤碳(C)和氮损失。我们发现在频繁火灾下,茎叶,根和微生物生物质的C / N比明显大于灭火。与这些模式一致,在频繁着火下,溶解的有机氮浓度降低了22%,靶向氮吸收的外酶活性增加了59%,这表明频繁着火增加了微生物对氮的限制。较高的表层土壤C和N以及火引起的土壤有机质N的增加表明,这些草丛森林中的频繁火灾通过微生物抗热原N的积累增强了微生物N的限制。结构方程模型证实了这些变化是相互关联的并降低了87%的微Stegium地上生物量和细根生物量高85%。这些发现提供了关于频繁火灾如何影响植物与土壤微生物相互作用的新见解,并因此可能在更长的时间内反馈给植物入侵。

更新日期:2021-02-26
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