Microbial community response to nitrogen deposition in northern forest ecosystems
Microbial community response to nitrogen deposition in northern forest ecosystems
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DOI：
10.1016/j.soilbio.2004.04.023
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发表时间：
2004-09
影响因子：
9.7
通讯作者：
M. Waldrop;D. Zak;R. Sinsabaugh
中科院分区：
文献类型：
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作者：
M. Waldrop;D. Zak;R. Sinsabaugh
温带森林的生产力通常受到土壤氮可用性的限制，这表明大气氮沉降的增加可能会增加生态系统的碳储存。然而，这种增加的幅度取决于土壤有机质形成的速率以及植物的生产速率。尽管如此，我们对大气氮沉降改变土壤微生物活动以及土壤有机质形成速率的潜力了解有限。由于高水平的无机氮会抑制白腐担子菌对木质素的氧化，并通常会增强纤维素的水解，因此我们假设大气中的氮沉积会以与酶活性变化一致的方式改变微生物分解，并将分解从真菌转移到效率较低的细菌。为了检验我们的想法，我们在三个北温带森林（黑橡木/白橡木（BOWO）、糖枫/红橡木（SMRO）和糖枫/椴木（SMBW））中实验控制了大气中的氮沉降（0、30和80kgNO3−-N）。一年后，我们测量了木质素分解和纤维素分解土壤酶的活性，并追踪了木质素和纤维素分解产物（13C-香草醛、儿茶酚和纤维二糖）的命运。在BOWO生态系统中，最高水平的氮沉降往往会降低酚氧化酶活性（131±13对104±5μmolh−1g−1）和过氧化物酶活性（210±26对190±21μmolh−1g−1），并减少13C-香草醛和13C-儿茶酚的降解以及13C进入真菌中 磷脂（p<0.05）。相反，在SMRO和SMBW生态系统中，氮沉降往往会增加酚氧化酶和过氧化物酶的活性，并增加香草醛和儿茶酚的降解以及同位素与真菌磷脂的结合（p<0.05）。我们观察到实验N沉积对13 C-纤维素的降解没有影响，尽管纤维素酶活性显示出小幅且略微显着的增加(p<0.10)。微生物活动和土壤碳循环对实验性氮添加的生态系统特定响应表明，准确预测土壤碳储存需要更好地了解微生物群落对大气氮沉降的生理反应。
The productivity of temperate forests is often limited by soil N availability, suggesting that elevated atmospheric N deposition could increase ecosystem C storage. However, the magnitude of this increase is dependent on rates of soil organic matter formation as well as rates of plant production. Nonetheless, we have a limited understanding of the potential for atmospheric N deposition to alter microbial activity in soil, and hence rates of soil organic matter formation. Because high levels of inorganic N suppress lignin oxidation by white rot basidiomycetes and generally enhance cellulose hydrolysis, we hypothesized that atmospheric N deposition would alter microbial decomposition in a manner that was consistent with changes in enzyme activity and shift decomposition from fungi to less efficient bacteria. To test our idea, we experimentally manipulated atmospheric N deposition (0, 30 and 80kgNO3−-N) in three northern temperate forests (black oak/white oak (BOWO), sugar maple/red oak (SMRO), and sugar maple/basswood (SMBW)). After one year, we measured the activity of ligninolytic and cellulolytic soil enzymes, and traced the fate of lignin and cellulose breakdown products (13C-vanillin, catechol and cellobiose). In the BOWO ecosystem, the highest level of N deposition tended to reduce phenol oxidase activity (131±13 versus 104±5μmolh−1g−1) and peroxidase activity (210±26 versus 190±21μmolh−1g−1) and it reduced13C-vanillin and13C-catechol degradation and the incorporation of13C into fungal phospholipids (p<0.05). Conversely, in the SMRO and SMBW ecosystems, N deposition tended to increase phenol oxidase and peroxidase activities and increased vanillin and catechol degradation and the incorporation of isotope into fungal phospholipids (p<0.05). We observed no effect of experimental N deposition on the degradation of13C-cellulose, although cellulase activity showed a small and marginally significant increase (p<0.10). The ecosystem-specific response of microbial activity and soil C cycling to experimental N addition indicates that accurate prediction of soil C storage requires a better understanding of the physiological response of microbial communities to atmospheric N deposition.