Hotspots of microbial activity induced by earthworm burrows, old root channels, and their combination in subsoil
Hotspots of microbial activity induced by earthworm burrows, old root channels, and their combination in subsoil
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DOI：
10.1007/s00374-016-1148-y
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发表时间：
2016-11-01
影响因子：
6.5
通讯作者：
Kuzyakov, Yakov
中科院分区：
文献类型：
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作者：
Hoang, Duyen T. T.;Pausch, Johanna;Kuzyakov, Yakov
生物孔隙是土壤中由根、蚯蚓或蚯蚓占据根孔而产生的孔隙或空隙，被认为是重要的微生物热点，特别是在底土中。我们假设蚯蚓（Lumbricus terrestris L.）对微生物活性的影响比腐烂的植物根（菊苣）强。因为添加了预先消化的有机物质。我们通过分析微生物量（C-MIC），总有机碳（C-org）和八种酶（纤维二糖水解酶，β-葡萄糖苷酶，木聚糖酶，酸性磷酸单酯酶，亮氨酸氨肽酶，酪氨酸氨肽酶，壳三糖苷酶和N-乙酰氨基葡萄糖苷酶）的活性，以105厘米的深度来测试这一假设。C-MIC的增加与生物孔隙中的C-org含量相比，散装土壤增加了两到三倍。土壤中C-mic-to-C-org的最高百分比（3.7 - 7.3%）表明蚯蚓对有机物分解的微生物效率提高。有机质的有效性提高了碳和氮靶向酶的活性1.2-11.3倍，但降低了10- 40%的酸性磷酸单酯酶活性的生物孔隙与散装土壤。在根孔中引入蚯蚓，与单独蚯蚓相比，微生物生物量增加1.5-1.8倍，酶活性增加1.2-1.9倍。土壤深度对根际土壤的生物化学性质影响很大，而对根际土壤的生物化学性质影响很小。综上所述，生物孔隙是土壤微生物碳、氮、磷转化的重要热点。蚯蚓对生物孔隙生化性质的影响大于腐烂根系。
Biopores are pores or voids in soil produced by roots, by earthworms, or by the occupation of earthworms in root pores, which are considered important microbial hotspots, especially in subsoil. We hypothesized that earthworms (Lumbricus terrestris L.) exert stronger effects on microbial activities than decaying plant roots (of Cichorium intybus L.) in the subsoil because of the addition of pre-digested organic material. We tested this hypothesis by analyzing microbial biomass (C-mic), total organic C (C-org), and activities of eight enzymes (cellobiohydrolase, beta-glucosidase, xylanase, acid phosphomonoesterase, leucine aminopeptidase, tyrosine aminopeptidase, chitotriosidase, and n-acetylglucosaminidase) down to 105-cm depth. The C-mic increase was associated with a two- to threefold increase of C-org content in biopores as compared to bulk soil. The highest percentage of C-mic-to-C-org (3.7 to 7.3 %) in the drilosphere demonstrated the enhancement of microbial efficiency for organic matter decomposition by earthworms. The availability of organic matter in biopores increased the activities of C- and N-targeting enzymes by 1.2-11.3 times, but reduced acid phosphomonoesterase activity by 10-40 % in biopores versus bulk soil. Introducing earthworms in root biopores caused 1.5-1.8 times higher microbial biomass and 1.2-1.9 times increased enzyme activities compared to the sole effect of earthworms. Soil depth showed a strong effect on the drilosphere, but only slight effects on the biochemical properties of root biopores and bulk soil. In conclusion, biopores are important microbial hotspots of C, N, and P transformations in subsoil. Earthworms exerted stronger effects on biochemical properties of biopores than decaying roots.