桉树凋落物对土壤微生物群落的影响:基于控制实验研究
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摘要
全面认识桉树种植对土壤微生物群落结构和功能的影响及机制,对于阐明单一物种对生态系统服务功能的影响具有重要意义。通过室内小盆模拟控制试验,采用随机区组设计,以土壤碳、氮含量有显著差异的3种天然次生林土壤为对象,以不添加凋落物的处理和添加天然次生林混合凋落物的处理为对照,研究桉树凋落物对土壤微生物群落结构及功能的影响。结果表明:(1)与天然次生林的混合凋落物相比,桉树凋落物具有较高的碳含量和较低的氮含量,其碳氮比也较高;(2)添加桉树凋落物的土壤中细菌、真菌、放线菌以及磷脂脂肪酸的总丰度显著高于不添加凋落物的土壤,但是显著低于添加天然次生林混合凋落物的土壤,并且不同凋落物处理下土壤微生物群落的磷脂脂肪酸组成存在显著差异;(3)不同凋落物处理下土壤微生物群落的碳代谢方式差异显著,添加桉树凋落物的土壤微生物群落的碳代谢功能优于未添加凋落物的处理,但是显著低于天然次生林混合凋落物处理的土壤,包括:碳代谢的活性和多样性。综上所述,与天然次生林本身的凋落物相比,桉树凋落物影响下的土壤微生物群落的生物量、多样性和代谢活性均较低,表明桉树凋落物为土壤微生物群落提供生境和食物的能力较弱。
【Objective】Eucalyptus is one of the main tree species introduced into the country for afforestation because of its fast growth and economic value. By the end of 2015, its plantation had expanded up to 4500000 hm~2. Afforestation of fast-growing Eucalyptus has received considerable attention with regard to its impacts on forest ecosystem. It is now known to affect physical and chemical properties of the soil, and plant community biodiversity. A number of studies have shown that it causes the soil degrading once it takes the place of native forests, but still little has been reported on its effects on soil microbial communities in South China. Soil microbial communities play a central role in litter decomposition, nutrient mineralization, and nearly all soil ecological processes in forest ecosystems, and may serve as an early indicator of changes in soil because of its rapid response to anthropogenic disturbances relative to soil biogeochemical properties. Litter decomposition provides the main source for soil microbial communities in forest ecosystems, whereas decomposition of Eucalyptus litter can disruptthe ecological associations between soil microbial communities and previous native communities. It is, therefore, very important to understand impacts of decomposition of Eucalyputs litter on structure and functions of the soil microbial community and its mechanisms to elucidating impacts of a single plant species on ecosystem services.【Method】 A simulation pot experiment was laid out in random block design and designed to determine impacts of Eucalyptus litter on structure and functions of the soil microbial community by means of comparison with mixed litter of natural secondary forest. Three types of natural secondary forest soils different in soil carbon and nitrogen contents were used in the experiment. A portion, 2 g each, of air-dried litter was mixed separately with 200 g(dry weight) soil in each pot, except for control(no litter added).Structure and functions of the soil microbial community in the soil of each pot were determined with the PLFA(phospholipid fatty acids) and BIOLOG(single carbon metabolism) methods, 10, 20 and 30 days after the decomposition started. 【Result】 Results show:(1) Eucalyptus litter was higher in carbon content but lower in nitrogen content than the litter of natural secondary forest, and so significantly higher in carbonnitrogen ratio;(2) PLFA abundances of bacteria, fungi, actinomyces and total PLFA were significantly higher in the soil treated with Eucalyptus litter than in the soil of the control, but significantly lower than in the soils treated with natural secondary forest litter; Principal component analysis(PCA) of the PLFA data shows that the treatment of Eucalyptus litter differed significantly from the treatments of mixed natural secondary forest litter in soil microbial community structure, and principal component one(PC1)explained 84.02% of the variation; and(3) PCA of the BIOLOG data also shows that significant differences existed between treatments in carbonutilization profiles of the soil microbial community, and PC1 and PC2 explained 36.99% and 16.95% of the variation, respectively; the treatment of Eucalyptus litter significantly lower than the treatments of natural secondary forest litter in carbon metabolic intensity, richness and diversity of soil microbial community, too. 【Conclusion】 All the findings in this study demonstrate that Eucalyptus litter is lower in capability of supplying soil microbial communities with adequate habitat and food than the mixed natural secondary forest litter.
【Objective】Eucalyptus is one of the main tree species introduced into the country for afforestation because of its fast growth and economic value. By the end of 2015, its plantation had expanded up to 4500000 hm~2. Afforestation of fast-growing Eucalyptus has received considerable attention with regard to its impacts on forest ecosystem. It is now known to affect physical and chemical properties of the soil, and plant community biodiversity. A number of studies have shown that it causes the soil degrading once it takes the place of native forests, but still little has been reported on its effects on soil microbial communities in South China. Soil microbial communities play a central role in litter decomposition, nutrient mineralization, and nearly all soil ecological processes in forest ecosystems, and may serve as an early indicator of changes in soil because of its rapid response to anthropogenic disturbances relative to soil biogeochemical properties. Litter decomposition provides the main source for soil microbial communities in forest ecosystems, whereas decomposition of Eucalyptus litter can disruptthe ecological associations between soil microbial communities and previous native communities. It is, therefore, very important to understand impacts of decomposition of Eucalyputs litter on structure and functions of the soil microbial community and its mechanisms to elucidating impacts of a single plant species on ecosystem services.【Method】 A simulation pot experiment was laid out in random block design and designed to determine impacts of Eucalyptus litter on structure and functions of the soil microbial community by means of comparison with mixed litter of natural secondary forest. Three types of natural secondary forest soils different in soil carbon and nitrogen contents were used in the experiment. A portion, 2 g each, of air-dried litter was mixed separately with 200 g(dry weight) soil in each pot, except for control(no litter added).Structure and functions of the soil microbial community in the soil of each pot were determined with the PLFA(phospholipid fatty acids) and BIOLOG(single carbon metabolism) methods, 10, 20 and 30 days after the decomposition started. 【Result】 Results show:(1) Eucalyptus litter was higher in carbon content but lower in nitrogen content than the litter of natural secondary forest, and so significantly higher in carbonnitrogen ratio;(2) PLFA abundances of bacteria, fungi, actinomyces and total PLFA were significantly higher in the soil treated with Eucalyptus litter than in the soil of the control, but significantly lower than in the soils treated with natural secondary forest litter; Principal component analysis(PCA) of the PLFA data shows that the treatment of Eucalyptus litter differed significantly from the treatments of mixed natural secondary forest litter in soil microbial community structure, and principal component one(PC1)explained 84.02% of the variation; and(3) PCA of the BIOLOG data also shows that significant differences existed between treatments in carbonutilization profiles of the soil microbial community, and PC1 and PC2 explained 36.99% and 16.95% of the variation, respectively; the treatment of Eucalyptus litter significantly lower than the treatments of natural secondary forest litter in carbon metabolic intensity, richness and diversity of soil microbial community, too. 【Conclusion】 All the findings in this study demonstrate that Eucalyptus litter is lower in capability of supplying soil microbial communities with adequate habitat and food than the mixed natural secondary forest litter.
引文
[1]谢耀坚.论中国桉树发展的贡献和可持续经营策略.桉树科技,2016,33(4):26-31Xie Y J. A discussion on the contribution and sustainable managementstrategy of eucalyptdevelopment in China(In Chinese). Eucalypt Science and Technology,2016, 33(4):26-31
[2]刘平,秦晶,刘建昌,等.桉树人工林物种多样性变化特征.生态学报,2011,31(8):2227-2235Liu P,Qin J,Liu J C, et al. Comparison of structure and species diversity of Eucalyptus community(In Chinese). Acta Ecologica Sinica, 2011,31(8):2227-2235
[3]马广超,丁晖,徐海根,等.桉树林取代马尾松树林后土壤动物组成变化研究.热带农业科学,2016, 36(4):35-40Ma G C, Ding H, Xu H G, et al. Soil animal composition change after Eucalyptus forest substituting Pinus massoniana forest(In Chinese). Chinese Journal of Tropical Agriculture,2016,36(4):35-40
[4]谭宏伟,杨尚东,吴俊,等.红壤区桉树人工林与不同林分土壤微生物活性及细菌多样性的比较.土壤学报,2014,51(3):575-584Tan H W,Yang S D, Wu J,et al. Comparison of Eucalyptus plantation with other forests in soil microbial activity and bacterial diversity in red soil region, China(In Chinese). Acta Pedologica Sinica, 2014, 51(3):575-584
[5]黎宏祥,王彬,王玉杰,等.不同林分类型对土壤团聚体稳定性及有机碳特征的影响.北京林业大学学报,2016,38(5):84-91Li H X, Wang B, Wang Y J, et al. Impact of different forest types on stability and organic carbon of soil aggregates(In Chinese). Journal of Beijing Forestry University,2016,38(5):84-91
[6]谭长强,彭玉华,申文辉,等.广西都安地区5种森林类型土壤机械组成及其肥力比较.生态科学,2017,36(2):119-125Tan Z Q,Peng Y H, Shen W H, et al. Study on soil the physical and chemical characteristics of 5characteristic forestsin Du'an area, Guangxi(In Chinese). Ecological Science, 2017,36(2):119-125
[7]张凯,郑华,陈法霖,等.桉树取代马尾松对土壤养分和酶活性的影响.土壤学报,2015, 52(3):646-653Zhang K, Zheng H, Chen F L, et al. Impacts of replacement of Pinus with Eucalyptus on soil nutrients and enzyme activities(In Chinese). Acta Pedologica Sinica, 2015, 52(3):646-653
[8]Banfield C C, Braun A C, Barra R,et al. Erosion proxies in an exotic tree plantation question the appropriate land use in central chile. Catena, 2018,161:77-84
[9]Becerra P I,Catford J A, Inderjit, et al. Inhibitory effects of Eucalyptus globulus on understorey plant growth and species richness are greater in non-native regions. Global Ecology and Biogeography, 2018,27(1):68-76
[10]Berthrong S T, Schadt C W, Pineiro G, et al.Afforestation alters the composition of functional genes in soil and biogeochemical processes in south american grasslands. Applied and Environmental Microbiology,2009,75(19):6240-6248
[11]Cortez C T,Nunes L,Rodrigues L B, et al. Soil microbial properties in Eucalyptus grandis plantations of different ages. Journal of Soil Science and Plant Nutrition, 2014, 14(3):734-742
[12]Fierro A, Grez A A, Vergara P M, et al. How does the replacement of native forest by exotic forest plantations affect the diversity, abundance and trophic structure of saproxylic beetle assemblages?Forest Ecology and Management, 2017,405:246-256
[13]Chen F L, Zheng H,Zhang K,et al. Changes in soil microbial community structure and metabolic activity following conversion from native Pinus massoniana plantations to exotic Eucalyptus plantations. Forest Ecology and Management, 2013,291:65-72
[14]鲍士旦.土壤农化分析.3版.北京:中国农业出版社.2000Bao S D. Soil and agricultural chemistry analysis(In Chinese). 3rd ed. Beijing:China Agriculture Press,2000
[15]Buyer J S,Teasdale J R,Roberts D P,et al. Factors affecting soil microbial community structure in tomato cropping systems. Soil Biology&Biochemistry,2010, 42(5):831-841
[16]Winding A. Fingerprinting bacterial soil communities using biolog microtitre plates//Ritz K, Dighton J,Giller K E. Beyond the biomass. Chichester:John Wiley and Sons, 1994
[17]Frostegard A, Baath E. The use of phospholipid fatty acid analysis to estimate bacterial and fungal biomass in soil. Biology and Fertility of Soils, 1996,22(1/2):59-65
[18]Olsson P A. Signature fatty acids provide tools for determination of the distribution and interactions of mycorrhizal fungi in soil. FEMS Microbiology Ecology,1999,29(4):303-310
[19]Zelles L. Fatty acid patterns of phospholipids and lipopolysaccharides in the characterisation of microbialcommunities in soil:A review. Biology and Fertility of Soils, 1999, 29(2):111-129
[20]Zelles L. Phospholipid fatty acid profiles in selected members of soil microbial communities.Chemosphere, 1997, 35(1/2):275-294
[21]Zelles L,Palojarvi A,Kandeler E,et al. Changes in soil microbial properties and phospholipid fatty acid fractions after chloroform fumigation. Soil Biology&Biochemistry, 1997, 29(9/10):1325-1336
[22]Garland J L, Mills A L. Classification and characterization of heterotrophic microbial communities on the basis of patterns of communitylevel sole-carbon-source utilization. Applied and Environmental Microbiology, 1991,57(8):2351-2359
[23]Hackett C A, Griffiths B S. Statistical analysis of the time-course of biolog substrate utilization. Journal of Microbiological Methods, 1997, 30(1):63-69
[24]陈法霖.桉树造林对土壤微生物群落结构和功能的影响.北京:中国科学院生态环境研究中心,2013Chen F L. Impacts of afforestation by Eucalyputs on structure and function of soil microbial communities(In Chinese). Beijing:Research Center for EcoEnvironmental Sciences, Chinese Academy of Sciences, 2013
[25]陈法霖,郑华,欧阳志云,等.土壤微生物群落结构对凋落物组成变化的响应.土壤学报,2011,48(3):603-611Chen F L, Zheng H, Ouyang Z Y, et al. Responses of microbial community structure to the leaf litter composition(In Chinese). Acta Pedologica Sinica,2011, 48(3):603-611
[26]陈法霖,郑华,阳柏苏,等.中亚热带几种针、阔叶树种凋落物混合分解对土壤微生物群落碳代谢多样性的影响.生态学报,2011,31(11):3027-3035Chen F L, Zheng H, Yang B S, et al. The decomposition of coniferous and broadleaf mixed litters significantly changes the carbon metabolism diversity of soil microbial communities in subtropical area, southern China(In Chinese). Acta Ecologica Sinica, 2011, 31(11):3027-3035
[27]Nasim G. Host allelopathy and arbuscular mycorrhizal fungi//Cheema Z A, Farooq M,Wahid A.Allelopathy:Current trends and future applications.Berlin, Heidelberg:Springer Berlin Heidelberg,2013:429-450
[28]Chander K, Goyal S,Kapoor K K. Microbial biomass dynamics during the decomposition of leaf litter of poplar and eucalyptus in a sandy loam. Biology andFertility of Soils,1995,19(4):357-362
[29]Heemsbergen D A,Berg M P,Loreau M,et al.Biodiversity effects on soil processes explained byinterspecific functional dissimilarity. Science, 2004,306(5698):1019-1020
[2]刘平,秦晶,刘建昌,等.桉树人工林物种多样性变化特征.生态学报,2011,31(8):2227-2235Liu P,Qin J,Liu J C, et al. Comparison of structure and species diversity of Eucalyptus community(In Chinese). Acta Ecologica Sinica, 2011,31(8):2227-2235
[3]马广超,丁晖,徐海根,等.桉树林取代马尾松树林后土壤动物组成变化研究.热带农业科学,2016, 36(4):35-40Ma G C, Ding H, Xu H G, et al. Soil animal composition change after Eucalyptus forest substituting Pinus massoniana forest(In Chinese). Chinese Journal of Tropical Agriculture,2016,36(4):35-40
[4]谭宏伟,杨尚东,吴俊,等.红壤区桉树人工林与不同林分土壤微生物活性及细菌多样性的比较.土壤学报,2014,51(3):575-584Tan H W,Yang S D, Wu J,et al. Comparison of Eucalyptus plantation with other forests in soil microbial activity and bacterial diversity in red soil region, China(In Chinese). Acta Pedologica Sinica, 2014, 51(3):575-584
[5]黎宏祥,王彬,王玉杰,等.不同林分类型对土壤团聚体稳定性及有机碳特征的影响.北京林业大学学报,2016,38(5):84-91Li H X, Wang B, Wang Y J, et al. Impact of different forest types on stability and organic carbon of soil aggregates(In Chinese). Journal of Beijing Forestry University,2016,38(5):84-91
[6]谭长强,彭玉华,申文辉,等.广西都安地区5种森林类型土壤机械组成及其肥力比较.生态科学,2017,36(2):119-125Tan Z Q,Peng Y H, Shen W H, et al. Study on soil the physical and chemical characteristics of 5characteristic forestsin Du'an area, Guangxi(In Chinese). Ecological Science, 2017,36(2):119-125
[7]张凯,郑华,陈法霖,等.桉树取代马尾松对土壤养分和酶活性的影响.土壤学报,2015, 52(3):646-653Zhang K, Zheng H, Chen F L, et al. Impacts of replacement of Pinus with Eucalyptus on soil nutrients and enzyme activities(In Chinese). Acta Pedologica Sinica, 2015, 52(3):646-653
[8]Banfield C C, Braun A C, Barra R,et al. Erosion proxies in an exotic tree plantation question the appropriate land use in central chile. Catena, 2018,161:77-84
[9]Becerra P I,Catford J A, Inderjit, et al. Inhibitory effects of Eucalyptus globulus on understorey plant growth and species richness are greater in non-native regions. Global Ecology and Biogeography, 2018,27(1):68-76
[10]Berthrong S T, Schadt C W, Pineiro G, et al.Afforestation alters the composition of functional genes in soil and biogeochemical processes in south american grasslands. Applied and Environmental Microbiology,2009,75(19):6240-6248
[11]Cortez C T,Nunes L,Rodrigues L B, et al. Soil microbial properties in Eucalyptus grandis plantations of different ages. Journal of Soil Science and Plant Nutrition, 2014, 14(3):734-742
[12]Fierro A, Grez A A, Vergara P M, et al. How does the replacement of native forest by exotic forest plantations affect the diversity, abundance and trophic structure of saproxylic beetle assemblages?Forest Ecology and Management, 2017,405:246-256
[13]Chen F L, Zheng H,Zhang K,et al. Changes in soil microbial community structure and metabolic activity following conversion from native Pinus massoniana plantations to exotic Eucalyptus plantations. Forest Ecology and Management, 2013,291:65-72
[14]鲍士旦.土壤农化分析.3版.北京:中国农业出版社.2000Bao S D. Soil and agricultural chemistry analysis(In Chinese). 3rd ed. Beijing:China Agriculture Press,2000
[15]Buyer J S,Teasdale J R,Roberts D P,et al. Factors affecting soil microbial community structure in tomato cropping systems. Soil Biology&Biochemistry,2010, 42(5):831-841
[16]Winding A. Fingerprinting bacterial soil communities using biolog microtitre plates//Ritz K, Dighton J,Giller K E. Beyond the biomass. Chichester:John Wiley and Sons, 1994
[17]Frostegard A, Baath E. The use of phospholipid fatty acid analysis to estimate bacterial and fungal biomass in soil. Biology and Fertility of Soils, 1996,22(1/2):59-65
[18]Olsson P A. Signature fatty acids provide tools for determination of the distribution and interactions of mycorrhizal fungi in soil. FEMS Microbiology Ecology,1999,29(4):303-310
[19]Zelles L. Fatty acid patterns of phospholipids and lipopolysaccharides in the characterisation of microbialcommunities in soil:A review. Biology and Fertility of Soils, 1999, 29(2):111-129
[20]Zelles L. Phospholipid fatty acid profiles in selected members of soil microbial communities.Chemosphere, 1997, 35(1/2):275-294
[21]Zelles L,Palojarvi A,Kandeler E,et al. Changes in soil microbial properties and phospholipid fatty acid fractions after chloroform fumigation. Soil Biology&Biochemistry, 1997, 29(9/10):1325-1336
[22]Garland J L, Mills A L. Classification and characterization of heterotrophic microbial communities on the basis of patterns of communitylevel sole-carbon-source utilization. Applied and Environmental Microbiology, 1991,57(8):2351-2359
[23]Hackett C A, Griffiths B S. Statistical analysis of the time-course of biolog substrate utilization. Journal of Microbiological Methods, 1997, 30(1):63-69
[24]陈法霖.桉树造林对土壤微生物群落结构和功能的影响.北京:中国科学院生态环境研究中心,2013Chen F L. Impacts of afforestation by Eucalyputs on structure and function of soil microbial communities(In Chinese). Beijing:Research Center for EcoEnvironmental Sciences, Chinese Academy of Sciences, 2013
[25]陈法霖,郑华,欧阳志云,等.土壤微生物群落结构对凋落物组成变化的响应.土壤学报,2011,48(3):603-611Chen F L, Zheng H, Ouyang Z Y, et al. Responses of microbial community structure to the leaf litter composition(In Chinese). Acta Pedologica Sinica,2011, 48(3):603-611
[26]陈法霖,郑华,阳柏苏,等.中亚热带几种针、阔叶树种凋落物混合分解对土壤微生物群落碳代谢多样性的影响.生态学报,2011,31(11):3027-3035Chen F L, Zheng H, Yang B S, et al. The decomposition of coniferous and broadleaf mixed litters significantly changes the carbon metabolism diversity of soil microbial communities in subtropical area, southern China(In Chinese). Acta Ecologica Sinica, 2011, 31(11):3027-3035
[27]Nasim G. Host allelopathy and arbuscular mycorrhizal fungi//Cheema Z A, Farooq M,Wahid A.Allelopathy:Current trends and future applications.Berlin, Heidelberg:Springer Berlin Heidelberg,2013:429-450
[28]Chander K, Goyal S,Kapoor K K. Microbial biomass dynamics during the decomposition of leaf litter of poplar and eucalyptus in a sandy loam. Biology andFertility of Soils,1995,19(4):357-362
[29]Heemsbergen D A,Berg M P,Loreau M,et al.Biodiversity effects on soil processes explained byinterspecific functional dissimilarity. Science, 2004,306(5698):1019-1020