Biopore history determines the microbial community composition in subsoil hotspots
Biopore history determines the microbial community composition in subsoil hotspots
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DOI：
10.1007/s00374-017-1201-5
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发表时间：
2017-07-01
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：
Banfield, Callum C.;Dippold, Michaela A.;Kuzyakov, Yakov
生物孔是养分调动的热点和碳(C)进入底土的捷径。碳处理依赖于微生物群落组成，这在地下生物孔中尚未被探索。磷脂脂肪酸（PLFAs，活微生物群标记物）和氨基糖（微生物坏死块标记物）从两个地下深度（45-75 cm; 75-105 cm）和三种生物孔类型中提取：(I)陆生蚓的钻圈，（II） 2岁的根生物孔和（III） 1.5岁的根生物孔加上6个6个月的陆生蚓活性。生物孔C含量比散装土壤至少高2.5倍，导致土壤的I磅PLFAs g（-1）高26-35倍。两种蚯蚓生物孔中PLFAs含量最高；因此，假定土壤有机质和养分周转最高。1磅PLFAs在根孔中比在蚯蚓孔中低33%。处理对微生物群落组成的影响比对土壤深度的影响更大，这表明生物孔中碳质量相似：根孔中革兰氏阳性菌（包括放线菌）比蚯蚓孔中更丰富，可能是由于蚯蚓孔中碳的生物利用度较低。两种蚯蚓孔隙类型都有新鲜凋落物输入，促进革兰氏阴性菌和真菌的生长。根孔中的蚯蚓在6个月内使微生物群落组成发生了较大的变化，使根孔转变为蚯蚓孔。只有最近的群落受到影响，它们反映了地下土壤热点地区微生物活动和功能的强烈异质性，而不同微生物群的生物孔特异性坏死块积累则不存在。
Biopores are hotspots of nutrient mobilisation and shortcuts for carbon (C) into subsoils. C processing relies on microbial community composition, which remains unexplored in subsoil biopores. Phospholipid fatty acids (PLFAs; markers for living microbial groups) and amino sugars (microbial necromass markers) were extracted from two subsoil depths (45-75 cm ; 75-105 cm) and three biopore types: (I) drilosphere of Lumbricus terrestris L., (II) 2-year-old root biopores and (III) 1.5-year-old root biopores plus six 6 months of L. terrestris activities. Biopore C contents were at least 2.5 times higher than in bulk soil, causing 26-35 times higher I pound PLFAs g(-1) soil. The highest I pound PLFAs were found in both earthworm biopore types; thus, the highest soil organic matter and nutrient turnover were assumed. I pound PLFAs was 33% lower in root pores than in earthworm pores. The treatment affected the microbial community composition more strongly than soil depth, hinting to similar C quality in biopores: Gram-positives including actinobacteria were more abundant in root pores than in earthworm pores, probably due to lower C bioavailability in the former. Both earthworm pore types featured fresh litter input, promoting growth of Gram-negatives and fungi. Earthworms in root pores shifted the composition of the microbial community heavily and turned root pores into earthworm pores within 6 months. Only recent communities were affected and they reflect a strong heterogeneity of microbial activity and functions in subsoil hotspots, whereas biopore-specific necromass accumulation from different microbial groups was absent.