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首页> 外文期刊>Soil Biology & Biochemistry >Exotic earthworms alter soil microbial community composition and function
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Exotic earthworms alter soil microbial community composition and function

机译：外来alter改变土壤微生物群落组成和功能

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Exotic earthworms can profoundly alter soil carbon (C) and nitrogen (N) dynamics in northern temperate forests, but the mechanisms explaining these responses are not well understood. We compared the soil microbial community (SMC) composition (measured as PLFAs) and enzyme activity between paired earthworm-invaded and earthworm-free plots in northern hardwood forests of New York, USA. We hypothesized that differences in SMCs and enzyme activity between plots would correspond with differences in soil C content and C:N ratios. Relative abundance of several bacterial (mostly gram-positive) PLFAs was higher and that of two fungal PLFAs was lower in earthworm compared to reference plots, largely because of earthworm incorporation of the organic horizon into mineral soil. In surface mineral soil earthworms increased arbuscular mycorrhizal fungi (AMF) and gram-positive bacterial PLFAs, and decreased fungal (mostly saprotrophic) and several bacterial (gram-negative and non-specific) PLFAs. Earthworms also increased the activities of cellulolytic relative to lignolytic enzymes in surface mineral soil, and the relationships between enzyme activities and components of the SMC suggest a substrate-mediated effect on the SMC and its metabolism of C. A highly significant relationship between components of the SMC and soil C:N also suggests that earthworms reduce soil C:N through functional and compositional shifts in the SMC. Finally, changes in AMF abundances were linked to phosphatase activity, suggesting that earthworms do not necessarily inhibit P-acquisition by AMF-associated plants in our study system. We conclude that the combined influence of earthworm-related changes in physical structure, accessibility and chemistry of organic matter, and relative abundance of certain groups of fungi and bacteria promote C metabolism, in particular by increasing the activities of cellulolytic vs. lignolytic enzymes
机译：外来earth可以深刻改变北部温带森林中土壤碳（C）和氮（N）的动态，但解释这些反应的机制尚不清楚。我们比较了美国纽约北部硬木森林中成对earth侵害和无earth成对的土壤微生物群落（SMC）组成（以PLFA衡量）和酶活性。我们假设样地之间SMC和酶活性的差异将与土壤C含量和C：N比的差异相对应。与参考样地相比，earth中几种细菌（大多数为革兰氏阳性）PLFA的相对丰度较高，而两种真菌PLFA的相对丰度较低，这主要是因为because将有机层整合到了矿物土壤中。在地表矿物土壤中，increased增加了丛枝菌根真菌（AMF）和革兰氏阳性细菌PLFA，减少了真菌（多数为腐生菌）和几种细菌（革兰氏阴性和非特异性）PLFA。 surface还增加了表层矿物土壤中相对于木质素分解酶的纤维素分解活性，酶活性与SMC成分之间的关​​系表明底物对SMC及其C的代谢具有介导的作用。 SMC和土壤C：N也表明through通过SMC中的功能和成分转移减少了土壤C：N。最后，AMF丰度的变化与磷酸酶活性有关，这表明earth不一定在我们的研究系统中抑制与AMF相关的植物对P的吸收。我们得出结论，worm相关的物理结构，有机物的可及性和化学变化以及某些真菌和细菌的相对丰度的综合影响，特别是通过增加纤维素分解酶和木质素分解酶的活性，促进了C代谢。

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