Dissolved organic carbon affects soil microbial activity and nitrogen dynamics in a Mexican tropical deciduous forest
Dissolved organic carbon affects soil microbial activity and nitrogen dynamics in a Mexican tropical deciduous forest
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DOI：
10.1007/s11104-007-9281-x
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发表时间：
2007-06-01
期刊：
影响因子：
4.9
通讯作者：
Jaramillo, Victor J.
中科院分区：
文献类型：
--
作者：
Manuel Montano, Noe;Garcia-Oliva, Felipe;Jaramillo, Victor J.
连续两年研究了墨西哥热带落叶林不同有机碳浓度（山顶和山坡）土壤中溶解有机碳（DOC）的季节变化及其对微生物活动和氮动态的影响。我们发现山顶土壤中的 DOC 浓度高于山坡土壤，并且在这两个研究年中，从旱季到雨季，两种土壤中的 DOC 浓度普遍下降。 DOC 较高的土壤中的微生物量和潜在碳矿化率、溶解性有机氮 (DON) 和 NH4+ 浓度以及净氮固定量均高于 DOC 较低的土壤。相反，在 DOC 最低的土壤中，净氮固定量和 NH4+ 浓度减少，而 NO3- 浓度和净硝化作用增加。净硝化作用与 DOC 浓度之间的负相关表明，当 C 有效性耗尽时，NH4+ 会被硝化菌转化为 NO3-。综上所述，我们的结果表明，可用碳似乎控制土壤微生物活性和氮动态，并且高可用碳刺激的活性异养微生物促进了微生物氮固定。异养微生物活性可用碳的减少会加剧土壤自养硝化作用。本研究提供了一个支持概念模型的实验数据集，以表明并强调微生物动态和氮转化可以与热带落叶森林土壤中的 DOC 可用性功能耦合。
Seasonal variation of dissolved organic C (DOC) and its effects on microbial activity and N dynamics were studied during two consecutive years in soils with different organic C concentrations (hilltop and hillslope) in a tropical deciduous forest of Mexico. We found that DOC concentrations were higher at the hilltop than at the hillslope soils, and in both soils generally decreased from the dry to the rainy season during the two study years. Microbial biomass and potential C mineralization rates, as well as dissolved organic N (DON) and NH4+ concentrations and net N immobilization were higher in soils with higher DOC than in soils with lower DOC. In contrast, net N immobilization and NH4+ concentration were depleted in the soil with lowest DOC, whereas NO3- concentrations and net nitrification increased. Negative correlations between net nitrification and DOC concentration suggested that NH4+ was transformed to NO3- by nitrifiers when the C availability was depleted. Taken together, our results suggest that available C appears to control soil microbial activity and N dynamics, and that microbial N immobilization is facilitated by active heterotrophic microorganisms stimulated by high C availability. Soil autotrophic nitrification is magnified by decreases in C availability for heterotrophic microbial activity. This study provides an experimental data set that supports the conceptual model to show and highlight that microbial dynamics and N transformations could be functionally coupled with DOC availability in the tropical deciduous forest soils.