Chronic nitrogen enrichment affects the structure and function of the soil microbial community in temperate hardwood and pine forests
Chronic nitrogen enrichment affects the structure and function of the soil microbial community in temperate hardwood and pine forests
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DOI：
10.1016/j.foreco.2004.03.018
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发表时间：
2004-07-12
影响因子：
3.7
通讯作者：
Simpson, RT
中科院分区：
文献类型：
--
作者：
Frey, SD;Knorr, M;Simpson, RT
研究了松木和阔叶林林分氮的长期富集对土壤细菌和真菌的相对丰度、功能容量和活性的影响。在2002年秋季，我们收集了一个土壤核心（5.6厘米直径，有机层加10厘米的矿质土），分别来自4个5米× 5米的控制地块，低氮（每年5克N m(-2)）和高氮（每年15 N m(-2)）的硬木和松林，在哈佛森林的慢性氮修正研究中。分析了样品的细菌和真菌总生物量和活性生物量、微生物分解代谢反应谱、纤维素和木质素分解酶的活性，以及总碳、不稳定碳和微生物来源的有机碳(C)。采集对照和低氮松样地的活根和细根，分析外生菌根真菌群落组成和多样性。阔叶林和松林施肥后活性真菌生物量分别比对照减少27-61%和42-69%。施氮量对活性细菌生物量影响不大，导致施氮地块真菌与细菌生物量比显著降低。微生物群落组成的这种转变伴随着酚氧化酶活性的显著降低，酚氧化酶是白腐真菌产生的木质素降解酶。在松林中，低氮处理区外生菌根真菌群落多样性低于对照区。在对照和施肥松地之间，还发现了外生菌根群落结构的差异，包括对照群落中相对频率最高的物种减少。最后，氮的富集改变了微生物底物利用的模式，即使在将数据归一化以解释微生物生物量的差异之后，氮处理的样地对添加羧酸和碳水化合物的相对响应也显著降低。这些模式与先前在该地点观察到的较低的分解速率和改变的氮循环一致。(C) 2004 Elsevier B.V.版权所有
We examined how chronic nitrogen (N) enrichment of pine and hardwood forest stands has affected the relative abundance, functional capacity, and activity of soil bacteria and fungi. During Fall 2002 we collected one soil core (5.6 cm diameter; organic horizon plus 10 cm of mineral soil) from each of four 5 m x 5 m subplots within the control, low N (5 g N m(-2) per year), and high N (15 N m(-2) per year) plots in both the hardwood and pine stands at the Chronic Nitrogen Amendment Study at Harvard Forest. The samples were analyzed for total and active bacterial and fungal biomass, microbial catabolic response profiles, the activities of cellulolytic and ligninolytic enzymes, and total, labile and microbially derived organic carbon (C). Live, fine roots were also collected from the control and low N pine plots and analyzed for ectomycorrhizal fungal community composition and diversity. Active fungal biomass was 27-61% and 42-69% lower in the fertilized compared to control plots in the hardwood and pine stands, respectively. Active bacterial biomass was not greatly affected by N additions, resulting in significantly lower fungal:bacterial biomass ratios in the N-treated plots. This shift in microbial community composition was accompanied by a significant reduction in the activity of phenol oxidase, a lignin-degrading enzyme produced by white-rot fungi. In the pine stand, ectomycorrhizal fungal community diversity was lower in the low N-treated plot than in the control plot. Differences in ectomycorrhizal community structure were also detected between control and fertilized pine plots, including a reduction in those species with the highest relative frequencies in the control community. Finally, N enrichment altered the pattern of microbial substrate use, with the relative response to the addition of carboxylic acids and carbohydrates being significantly lower in the N-treated plots, even after the data were normalized to account for differences in microbial biomass. These patterns are consistent with lower decomposition rates and altered N cycling observed previously at this site. (C) 2004 Elsevier B.V. All rights reserved.