引用本文:曹林桦,刘彩霞,刘 茗,方 伟,梁辰飞,秦 华,陈俊辉,徐秋芳.集约经营对毛竹林土壤反硝化细菌丰度的影响[J].土壤学报,2020,57(3):710-720. DOI:10.11766/trxb201810150520
CAO Linhua,LIU Caixia,LIU Ming,FANG Wei,LIANG Chenfei,QIN Hua,CHEN Junhui,XU Qiufang.Effects of Intensive Management Practice on Functional Gene Abundance of Denitrifying Bacteria in the Soil of Moso Bamboo (Phyllostachys heterocycla) Plantation[J].Acta Pedologica Sinica,2020,57(3):710-720. DOI:10.11766/trxb201810150520
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集约经营对毛竹林土壤反硝化细菌丰度的影响
曹林桦, 刘彩霞, 刘茗, 方伟, 梁辰飞, 秦华, 陈俊辉, 徐秋芳
浙江农林大学
摘要:
为探究集约经营过程中反硝化细菌丰度的变化情况,采用实时荧光定量PCR(real-time PCR)方法,对集约经营0(CK)、10、15、20、25 a毛竹林表层(0~20 cm)和亚表层(20~40 cm)三种反硝化细菌nirKnirSnosZ丰度进行分析。结果表明:毛竹林土壤反硝化细菌基因丰度(1.45×106~3.03×108copies•g-1干土)高于其他生态系统。随着集约经营时间的增加,两层土壤的三种功能基因丰度在集约经营10年时表现增加或不变的一致规律。除表层土壤nirS基因外,三种功能基因在集约经营过程的某一阶段(15或20 a)出现不同程度的下降;但集约经营持续25 a时,除表层土壤nosZ基因丰度仍低于对照外,其他基因丰度均恢复甚至超过对照水平,说明土壤反硝化细菌表现出对集约经营干扰的抵抗和恢复反应。表层nirSnosZ土壤基因丰度显著高于亚表层土壤,但nirK基因丰度出现相反现象。土壤性质与基因丰度的相关性分析和冗余分析表明,集约经营措施对土壤反硝化细菌影响明显,主要通过土壤氮和有机碳变化综合影响反硝化细菌的活动和功能。毛竹林集约经营土壤的反硝化细菌功能基因丰度较高,积极参与氮循环过程,可加剧N2 O温室气体的排放。
关键词:  反硝化细菌  集约经营  毛竹林  实时荧光定量PCR
基金项目:国家自然科学基金项目(31570602)和浙江省自然科学基金重点项目(LZ16C160002)
Effects of Intensive Management Practice on Functional Gene Abundance of Denitrifying Bacteria in the Soil of Moso Bamboo (Phyllostachys heterocycla) Plantation
Cao Linhua, Liu Caixia, Liu Ming, Fang Wei, Liang Chenfei, Qin Hua, Chen Junhui, Xu Qiufang
Zhejiang Agriculture and Forestry University
Abstract:
【Objective】Moso bamboo (Phyllostachys heterocycla) is an important non-timber forest resource in subtropical China. Intensive bamboo forest management, beginning in the 1980s, has enormously increased the area of moso bamboo plantations and economic return for farmers. However, these long-term management practices, such as removal of understories and excessive application of nitrogen fertilizers combined with tillage, have already brought about some negative impacts, such as significantly altering soil microbial communities and increasing N2 O emission, of which the latter possibly reflects changes in the population of denitrifying bacteria. To explore this possibility, investigations were made of abundance of denitrifying bacteria in moso bamboo plantations under long-term intensive management. 【Method】Soil samples were collected from the surface (0~20 cm) and subsurface (20~40 cm) soil layers of moso bamboo plantations receiving 0 (CK), 10, 15, 20 and 25 years of intensive management, for analysis of abundances of denitrifying communities (nirK-, nirS - and nosZ-denitrifiers). In addition with the aid of real-time quantitative PCR, and for analysis of soil physicochemical properties in an attempt to determine major factors that contribute the most to alteration of denitrifying bacteria in abundance. 【Result】It was found that the abundances of soil denitrifying bacteria in the moso bamboo plantations (1.45×106~3.03×108 copies•g-1 dry soil) were generally higher than those reported for other ecosystems, except in the case of nirS in farmland. Abundances of the three functional genes in both soil layers increased or remained unchanged during the first 10 years of intensive management. With the exception of nirS in the surface soil, all three functional genes then decreased somewhat after either 15 or 20 years of intensive management. Eventually however, and with the exception of nosZ in the surface soil, abundances of the other genes recovered or even exceeded the level in control after 25 years of intensive management, indicating a resistence of denitrifying bacteria to disturbance caused by intensive management practices. The abundances of nirS and nosZ in the surface soil samples were significantly higher than those in the subsurface soil samples, but nirK showed an a reverse trend. This phenomenon possibly reflects the observed decreases in pH and dissolved organic carbon excreted by bamboo root in the subsurface soil. Correlation analysis between soil physicochemical properties and functional genes reveals that the denitrifying genes, nirK, nirS, and nosZ, were positively related to total N, available P, and organic carbon in the surface soils. Additionally, nosZ was also positively related to C/N. However, in the subsurface soils, all the three denitrification genes as a group were significantly and positively related to organic carbon. Redundancy analysis demonstrates that the impacts of intensive management significantly on denitrifying bacteria were main reflected in the comprehensive effects of soil nitrogen and organic carbon on activities and functioning of the bacteria. 【Conclusion】In summary, all the findings in this study indicate that long-term intensive management substantially alters both soil physicochemical properties and associated denitrifying bacterial communities. But the effect varies with soil layer, which means that depth of the soil is also a key factor affecting composition of the denitrifying bacterial community. Compared to some other ecosystems, the intensively managed moso bamboo plantations are relatively higher in abundance of denitrifying bacterial functional genes. Active participation of these bacteria in nitrogen recycling leads to increased emission of N2O. Therefore, it is suggested that growers should use slow-release N fertilizers to reduce the concentration of ammonium nitrogen in the soil solution, thus encourage plant to absorb ammonium before it is nitrified. This strategy is believed to be able to decrease production of nitrate and hence denitrification and N2O emissions.
Key words:  Denitrifying bacteria  Intensive management  Phyllostachys heterocycla  Real-time quantitative PCR