Soil C and N availability determine the priming effect: microbial N mining and stoichiometric decomposition theories
Soil C and N availability determine the priming effect: microbial N mining and stoichiometric decomposition theories
复制标题
土壤碳和氮的有效性决定了启动效应：微生物氮开采和化学计量分解理论
DOI：
10.1111/gcb.12475
复制
发表时间：
2014-07-01
影响因子：
11.6
通讯作者：
Kuzyakov, Yakov
中科院分区：
文献类型：
--
作者：
Chen, Ruirui;Senbayram, Mehmet;Kuzyakov, Yakov
生态系统中人为氮 (N) 的输入量不断增加，引发了一个关键问题：有效氮如何改变分解者群落，从而影响土壤有机质 (SOM) 的矿化。此外，氮输入改变了启动效应（PE），即新鲜有机物对SOM微生物分解的影响。我们研究了 C 和 N 对 SOM 矿化（通过在 C3 土壤中添加 C4 蔗糖或 C4 玉米秸秆的天然 13C 标记）的相互作用，以及微生物生长动力学和五种水解酶的活性。这包括控制两种启动效应机制的参数组——微生物氮开采和化学计量分解理论。在单独的 C 处理中，正 PE 伴随着特定微生物生长速率的下降，证实了 K 策略对天然 SOM 分解的更大贡献。添加蔗糖和氮显着加速了天然 SOM 的矿化，而添加植物残留物的矿物质氮则加速了植物残留物的分解。这支持了氮限制方面的微生物采矿理论。添加蔗糖和氮会加速微生物生长，增加β-葡萄糖苷酶和纤维二糖水解酶的活性，并降低木聚糖酶和亮氨酸氨基肽酶的活性。这表明 r-策略对 PE 和纤维素分解的贡献增加，但半纤维素分解和蛋白水解活性降低。因此，C循环的加速是由外源有机C引发并受N控制。这证实了化学计量分解理论。 K-和r-策略都有利于启动效应，在氮限制下，K-选择物种的贡献不断增加。因此，“微生物氮开采”理论中描述的启动现象可以归因于钾战略家。相比之下，“化学计量分解”理论，即由于微生物平衡生长而加速 OM 矿化，可以通过 r 策略的主导来解释。
The increasing input of anthropogenically derived nitrogen (N) to ecosystems raises a crucial question: how does available N modify the decomposer community and thus affects the mineralization of soil organic matter (SOM). Moreover, N input modifies the priming effect (PE), that is, the effect of fresh organics on the microbial decomposition of SOM. We studied the interactive effects of C and N on SOM mineralization (by natural 13C labelling adding C4‐sucrose or C4‐maize straw to C3‐soil) in relation to microbial growth kinetics and to the activities of five hydrolytic enzymes. This encompasses the groups of parameters governing two mechanisms of priming effects – microbial N mining and stoichiometric decomposition theories. In sole C treatments, positive PE was accompanied by a decrease in specific microbial growth rates, confirming a greater contribution of K‐strategists to the decomposition of native SOM. Sucrose addition with N significantly accelerated mineralization of native SOM, whereas mineral N added with plant residues accelerated decomposition of plant residues. This supports the microbial mining theory in terms of N limitation. Sucrose addition with N was accompanied by accelerated microbial growth, increased activities of β‐glucosidase and cellobiohydrolase, and decreased activities of xylanase and leucine amino peptidase. This indicated an increased contribution of r‐strategists to the PE and to decomposition of cellulose but the decreased hemicellulolytic and proteolytic activities. Thus, the acceleration of the C cycle was primed by exogenous organic C and was controlled by N. This confirms the stoichiometric decomposition theory. Both K‐ and r‐strategists were beneficial for priming effects, with an increasing contribution of K‐selected species under N limitation. Thus, the priming phenomenon described in ‘microbial N mining’ theory can be ascribed to K‐strategists. In contrast, ‘stoichiometric decomposition’ theory, that is, accelerated OM mineralization due to balanced microbial growth, is explained by domination of r‐strategists.