凋落物多样性及组成对凋落物分解和土壤微生物群落的影响
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摘要
凋落物分解是生态系统营养物质循环的核心过程,而土壤微生物群落在凋落物分解过程中扮演着极其重要且不可替代的角色。随着生物多样性的丧失日益严峻,探讨凋落物多样性及组成对凋落物分解和土壤微生物群落的影响,不仅有助于了解凋落物分解的内在机制,而且可为退化草原生态系统的恢复提供参考。以内蒙古呼伦贝尔草原退化恢复群落中的草本植物为研究对象,依据植物多度、盖度、频度和物种的重要值及其在群落中的恢复程度筛选出排序前4的羊草(Leymus chinensis)、茵陈蒿(Artemisia capillaris)、麻花头(Serratula centauroides)、二裂委陵菜(Potentilla bifurca)的凋落物为实验材料,通过设置3种凋落物多样性水平(1,2,4),包括11种凋落物组合(单物种凋落物共4种,两物种凋落物混合共6种,四物种凋落物混合共1种),利用磷脂脂肪酸(PLFA)方法来研究分解60 d后凋落物多样性及组成对凋落物分解和土壤微生物群落的影响。结果表明:(1)凋落物物种多样性仅对C残余率具有显著影响,表现在两物种混合凋落物C残余率显著低于单物种凋落物,而凋落物组成对所观测的4个凋落物分解参数(质量、C、N残余率以及C/N)均具有显著影响;(2)凋落物物种多样性对细菌(B)含量具有显著影响,而凋落物组成对真菌(F)含量具有显著影响,两者对F/B以及微生物总量均无显著影响;(3)冗余分析结果表明凋落物组成与凋落物分解相关指标(凋落物质量、C、N残余率及C/N)和土壤微生物(真菌、细菌含量)的相关关系高于凋落物多样性。(4)进一步建立结构方程模型(Structural Equation Model,SEM)发现,凋落物初始C含量对凋落物质量、C、N残余率及C/N有显著正的直接影响;凋落物木质素含量对凋落物质量、C、N残余率有显著正的直接影响;凋落物初始N含量对N残余率有显著正的直接影响,而对C残余率及C/N有显著负的直接影响;凋落物初始C/N对凋落物质量、N残余率有显著正的直接影响,而对C/N有显著负的直接影响。此外,凋落物初始C、N、木质素含量及C/N均对真菌含量具有显著正影响,并可通过真菌对凋落物质量分解产生显著负的间接影响。以上结果表明该退化恢复区域优势种凋落物分解以初始C、木质素为主导,主要通过土壤真菌影响凋落物的分解进程,这将减缓凋落物的分解速率进而减慢草原生态系统的进程。这些结果为凋落物多样性及组成对自身分解和土壤微生物群落的影响提供了实验依据,也为进一步分析凋落物分解内在机制以及草原生态系统的恢复提供了数据参考。
Litter decomposition is the core process of the nutrient substance cycles in the ecosystem, and the soil microbial community plays an important and irreplaceable role in litter decomposition. Recently, the loss of diversity has become a serious issue because of climate changes and human activities, which would influence litter diversity and composition in the community. Therefore, in the present study, we examined how litter diversity and its composition affect the soil microbial community and litter decomposition characteristics. We focused on the typical steppe community of Hulun Buir in the Inner Mongolia Steppe, China, where the grassland has degraded in the past few decades. In a restoration community, we collected the litter of the first four most abundant species: Leymus chinensis, Artemisia capillaris, Serratula centauroides, and Potentilla bifurca. Litter diversity treatments were set up under controlled conditions: 1-, 2-, and 4-species treatments. The 1-species litter treatment included 4 types of composition(each of the four species), 2-species litter treatment included 6 types of composition(litter of pairwise species among the four species), and 4-species litter treatment included 1 type of composition(all the four species). After 60 days of decomposition, the litter decomposition characteristics were estimated and corresponding soil microorganisms were analyzed using the phospholipid fatty acid(PLFA) method. The results showed as follows(1) Litter diversity only had a significant effect on the C remaining rate. The C remaining rate of mixed litter was significantly lower than that of single litter, whereas litter composition had a significant effect on the four decomposition parameters(mass, C, N remaining rate, and C/N).(2) Litter diversity had a significant effect on bacterial PLFAs content, whereas litter composition had a significant effect on fungal PLFAs content. Both factors had no significant effects on F/B or total PLFAs.(3) The redundancy analysis showed that litter composition had a greater impact on the decomposition parameters(mass, C, N remaining rate, and C/N) and soil microbe(bacteria and fungi) than litter diversity.(4) The structural equation model showed that the initial litter C content had significantly and directly positive effects on litter mass, C and N remaining rate, and C/N. The initial litter lignin content had significantly and directly positive effects on litter mass, C and N remaining rate. The initial litter N content had significantly and directly positive effects on the N remaining rate, whereas it had significantly and directly negative effects on litter C remaining rate and C/N. The initial litter C/N had significantly and directly positive effects on litter mass and N remaining rate, whereas it had significantly and directly negative effects on litter C/N. In addition, initial litter C, N, and lignin content and initial litter C/N all had significant effects on the fungal content, which had significantly and indirectly negative effects on the litter mass remaining rate. The results showed that the litter of dominant species in the restoration area was difficult to decompose, even though it was in the beginning stage. The decomposition process was mainly controlled by fungi, which would decrease the litter decomposition rate and thus slow down the grassland ecosystem process. These results will provide scientific evidence for the effects of litter diversity/composition on microbial community and theoretical proof for further analysis of the effects of species composition on the ecological function of restoration grassland.
Litter decomposition is the core process of the nutrient substance cycles in the ecosystem, and the soil microbial community plays an important and irreplaceable role in litter decomposition. Recently, the loss of diversity has become a serious issue because of climate changes and human activities, which would influence litter diversity and composition in the community. Therefore, in the present study, we examined how litter diversity and its composition affect the soil microbial community and litter decomposition characteristics. We focused on the typical steppe community of Hulun Buir in the Inner Mongolia Steppe, China, where the grassland has degraded in the past few decades. In a restoration community, we collected the litter of the first four most abundant species: Leymus chinensis, Artemisia capillaris, Serratula centauroides, and Potentilla bifurca. Litter diversity treatments were set up under controlled conditions: 1-, 2-, and 4-species treatments. The 1-species litter treatment included 4 types of composition(each of the four species), 2-species litter treatment included 6 types of composition(litter of pairwise species among the four species), and 4-species litter treatment included 1 type of composition(all the four species). After 60 days of decomposition, the litter decomposition characteristics were estimated and corresponding soil microorganisms were analyzed using the phospholipid fatty acid(PLFA) method. The results showed as follows(1) Litter diversity only had a significant effect on the C remaining rate. The C remaining rate of mixed litter was significantly lower than that of single litter, whereas litter composition had a significant effect on the four decomposition parameters(mass, C, N remaining rate, and C/N).(2) Litter diversity had a significant effect on bacterial PLFAs content, whereas litter composition had a significant effect on fungal PLFAs content. Both factors had no significant effects on F/B or total PLFAs.(3) The redundancy analysis showed that litter composition had a greater impact on the decomposition parameters(mass, C, N remaining rate, and C/N) and soil microbe(bacteria and fungi) than litter diversity.(4) The structural equation model showed that the initial litter C content had significantly and directly positive effects on litter mass, C and N remaining rate, and C/N. The initial litter lignin content had significantly and directly positive effects on litter mass, C and N remaining rate. The initial litter N content had significantly and directly positive effects on the N remaining rate, whereas it had significantly and directly negative effects on litter C remaining rate and C/N. The initial litter C/N had significantly and directly positive effects on litter mass and N remaining rate, whereas it had significantly and directly negative effects on litter C/N. In addition, initial litter C, N, and lignin content and initial litter C/N all had significant effects on the fungal content, which had significantly and indirectly negative effects on the litter mass remaining rate. The results showed that the litter of dominant species in the restoration area was difficult to decompose, even though it was in the beginning stage. The decomposition process was mainly controlled by fungi, which would decrease the litter decomposition rate and thus slow down the grassland ecosystem process. These results will provide scientific evidence for the effects of litter diversity/composition on microbial community and theoretical proof for further analysis of the effects of species composition on the ecological function of restoration grassland.
引文
[1] 王珍.锡林河流域典型草原生物多样性及其与生产力的关系[D].呼和浩特:内蒙古大学,2017.
[2] Cebrian J.Patterns in the fate of production in plant communities.American Naturalist,1999,154(4):449- 468.
[3] Swift M J,Heal O W,Anderson J M.Decomposition in terrestrial ecosystems.Studies in Ecology,1979,5:372- 372.
[4] Potthoff M,Dyckmans J,Flessa H,Beese F,Joergensen R G.Decomposition of maize residues after manipulation of colonization and its contribution to the soil microbial biomass.Biology and Fertility of Soils,2008,44(6):891- 895.
[5] 许湘琴,林植华,陈慧丽.凋落物分解对土壤生物的影响.生态学杂志,2011,30(6):1258- 1264.
[6] Scheibe A,Steffens C,Seven J,Jacob A,Hertel D,Leuschner C,Gleixner G.Effects of tree identity dominate over tree diversity on the soil microbial community structure.Soil Biology and Biochemistry,2015,81:219- 227.
[7] Xiao C W,Zhou Y,Su J Q,Yang F.Effects of plant functional group loss on soil microbial community and litter decomposition in a steppe vegetation.Frontiers in Plant Science,2017,8:2040.
[8] 李姗姗,王正文,杨俊杰.凋落物分解过程中土壤微生物群落的变化.生物多样性,2016,24(2):195- 204.
[9] Bray S R,Kitajima K,Mack M C.Temporal dynamics of microbial communities on decomposing leaf litter of 10 plant species in relation to decomposition rate.Soil Biology and Biochemistry,2012,49:30- 37.
[10] Xie Y Z,Wittig R.The impact of grazing intensity on soil characteristics of Stipa grandis and Stipa bungeana steppe in northern China (autonomous region of Ningxia).Acta Oecologica,2004,25(3):197- 204.
[11] 宋明华,刘丽萍,陈锦,张宪洲.草地生态系统生物和功能多样性及其优化管理.生态环境学报,2018,27(6):1179- 1188.
[12] 辛晓静.物种混合及CO2浓度倍增对呼伦贝尔草原区常见物种凋落物分解的影响[D].天津:南开大学,2016.
[13] Spadaro A,Ajello A,Morace C,Zirilli A,D′Arrigo G,Luigiano C,Martino F,Bene A,Migliorato D,Turiano S,Ferraù O,Freni M A.Serum chromogranin-A in hepatocellular carcinoma:diagnostic utility and limits.World Journal of Gastroenterology,2005,11(13):1987- 1990.
[14] Zelles L.Fatty acid patterns of phospholipids and lipopolysaccharides in the characterisation of microbial communities in soil:a review.Biology and Fertility of Soils,1999,29(2):111- 129.
[15] 辛晓静,刘磊,申俊芳,赵念席,高玉葆.羊草基因型数目与氮添加对土壤微生物群落的交互影响.生态学报,2016,36(13):3923- 3932.
[16] Zhou Y,Clark M,Su J Q,Xiao C W.Litter decomposition and soil microbial community composition in three Korean pine (Pinus koraiensis) forests along an altitudinal gradient.Plant and Soil,2015,386(1/2):171- 183.
[17] Chang C H,Wu F Z,Yang W Q,Xu Z F,Cao R,He W,Tan B,Justine M F.The microbial community in decaying fallen logs varies with critical period in an alpine forest.PLoS One,2017,12(8):e0182576.
[18] Thoms C,Gleixner G.Seasonal differences in tree species′ influence on soil microbial communities.Soil Biology and Biochemistry,2013,66:239- 248.
[19] Li S S,Tong Y W,Wang Z W.Species and genetic diversity affect leaf litter decomposition in subtropical broadleaved forest in southern China.Journal of Plant Ecology,2017,10(1):232- 241.
[20] Zuo X A,Knops J M H.Effects of elevated CO2,increased nitrogen deposition,and plant diversity on aboveground litter and root decomposition.Ecosphere,2018,9(2):e02111.
[21] López-Rojo N,Martínez A,Pérez J,Basaguren A,Pozo J,Boyero L.Leaf traits drive plant diversity effects on litter decomposition and FPOM production in streams.PLoS One,2018,13(5):e0198243.
[22] Chapman S K,Newman G S.Biodiversity at the plant-soil interface:microbial abundance and community structure respond to litter mixing.Oecologia,2010,162(3):763- 769.
[23] Wang H,Liu S R,Wang J X,Shi Z M,Xu J,Hong P Z,Ming A G,Yu H L,Chen L,Lu L H,Cai D X.Differential effects of conifer and broadleaf litter inputs on soil organic carbon chemical composition through altered soil microbial community composition.Scientific Reports,2016,6:27097.
[24] Santonja M,Rancon A,Fromin N,Baldy V,H?ttenschwiler S,Fernandez C,Montès N,Mirleau P.Plant litter diversity increases microbial abundance,fungal diversity,and carbon and nitrogen cycling in a Mediterranean shrubland.Soil Biology and Biochemistry,2017,111:124- 134.
[25] Palm C A,Sanchez P A.Nitrogen release from the leaves of some tropical legumes as affected by their lignin and polyphenolic contents.Soil Biology and Biochemistry,1991,23(1):83- 88.
[26] Kemp P R,Reynolds J F,Virginia R A,Whitford W G.Decomposition of leaf and root litter of Chihuahuan desert shrubs:effects of three years of summer drought.Journal of Arid Environments,2003,53(1):21- 39.
[27] Potthoff M,Steenwerth K L,Jackson L E,Drenovsky R E,Scow K M,Joergensen R G.Soil microbial community composition as affected by restoration practices in California grassland.Soil Biology and Biochemistry,2006,38(7):1851- 1860.
[28] Jacob M,Leuschner C,Thomas F M.Productivity of temperate broad-leaved forest stands differing in tree species diversity.Annals of Forest Science,2010,67(5):503- 503.
[29] Austin A T,Ballaré C L.Dual role of lignin in plant litter decomposition in terrestrial ecosystems.Proceedings of the National Academy of Sciences of the United States of America,2010,107(10):4618- 4622.
[30] 于雯超,宋晓龙,修伟明,张贵龙,赵建宁,杨殿林.氮素添加对贝加尔针茅草原凋落物分解的影响.草业学报,2014,23(5):49- 60.
[31] 李文亚,邱璇,白龙,杨殿林.氮、磷添加对贝加尔针茅草原凋落物分解的影响.草业学报,2017,26(8):43- 53.
[2] Cebrian J.Patterns in the fate of production in plant communities.American Naturalist,1999,154(4):449- 468.
[3] Swift M J,Heal O W,Anderson J M.Decomposition in terrestrial ecosystems.Studies in Ecology,1979,5:372- 372.
[4] Potthoff M,Dyckmans J,Flessa H,Beese F,Joergensen R G.Decomposition of maize residues after manipulation of colonization and its contribution to the soil microbial biomass.Biology and Fertility of Soils,2008,44(6):891- 895.
[5] 许湘琴,林植华,陈慧丽.凋落物分解对土壤生物的影响.生态学杂志,2011,30(6):1258- 1264.
[6] Scheibe A,Steffens C,Seven J,Jacob A,Hertel D,Leuschner C,Gleixner G.Effects of tree identity dominate over tree diversity on the soil microbial community structure.Soil Biology and Biochemistry,2015,81:219- 227.
[7] Xiao C W,Zhou Y,Su J Q,Yang F.Effects of plant functional group loss on soil microbial community and litter decomposition in a steppe vegetation.Frontiers in Plant Science,2017,8:2040.
[8] 李姗姗,王正文,杨俊杰.凋落物分解过程中土壤微生物群落的变化.生物多样性,2016,24(2):195- 204.
[9] Bray S R,Kitajima K,Mack M C.Temporal dynamics of microbial communities on decomposing leaf litter of 10 plant species in relation to decomposition rate.Soil Biology and Biochemistry,2012,49:30- 37.
[10] Xie Y Z,Wittig R.The impact of grazing intensity on soil characteristics of Stipa grandis and Stipa bungeana steppe in northern China (autonomous region of Ningxia).Acta Oecologica,2004,25(3):197- 204.
[11] 宋明华,刘丽萍,陈锦,张宪洲.草地生态系统生物和功能多样性及其优化管理.生态环境学报,2018,27(6):1179- 1188.
[12] 辛晓静.物种混合及CO2浓度倍增对呼伦贝尔草原区常见物种凋落物分解的影响[D].天津:南开大学,2016.
[13] Spadaro A,Ajello A,Morace C,Zirilli A,D′Arrigo G,Luigiano C,Martino F,Bene A,Migliorato D,Turiano S,Ferraù O,Freni M A.Serum chromogranin-A in hepatocellular carcinoma:diagnostic utility and limits.World Journal of Gastroenterology,2005,11(13):1987- 1990.
[14] Zelles L.Fatty acid patterns of phospholipids and lipopolysaccharides in the characterisation of microbial communities in soil:a review.Biology and Fertility of Soils,1999,29(2):111- 129.
[15] 辛晓静,刘磊,申俊芳,赵念席,高玉葆.羊草基因型数目与氮添加对土壤微生物群落的交互影响.生态学报,2016,36(13):3923- 3932.
[16] Zhou Y,Clark M,Su J Q,Xiao C W.Litter decomposition and soil microbial community composition in three Korean pine (Pinus koraiensis) forests along an altitudinal gradient.Plant and Soil,2015,386(1/2):171- 183.
[17] Chang C H,Wu F Z,Yang W Q,Xu Z F,Cao R,He W,Tan B,Justine M F.The microbial community in decaying fallen logs varies with critical period in an alpine forest.PLoS One,2017,12(8):e0182576.
[18] Thoms C,Gleixner G.Seasonal differences in tree species′ influence on soil microbial communities.Soil Biology and Biochemistry,2013,66:239- 248.
[19] Li S S,Tong Y W,Wang Z W.Species and genetic diversity affect leaf litter decomposition in subtropical broadleaved forest in southern China.Journal of Plant Ecology,2017,10(1):232- 241.
[20] Zuo X A,Knops J M H.Effects of elevated CO2,increased nitrogen deposition,and plant diversity on aboveground litter and root decomposition.Ecosphere,2018,9(2):e02111.
[21] López-Rojo N,Martínez A,Pérez J,Basaguren A,Pozo J,Boyero L.Leaf traits drive plant diversity effects on litter decomposition and FPOM production in streams.PLoS One,2018,13(5):e0198243.
[22] Chapman S K,Newman G S.Biodiversity at the plant-soil interface:microbial abundance and community structure respond to litter mixing.Oecologia,2010,162(3):763- 769.
[23] Wang H,Liu S R,Wang J X,Shi Z M,Xu J,Hong P Z,Ming A G,Yu H L,Chen L,Lu L H,Cai D X.Differential effects of conifer and broadleaf litter inputs on soil organic carbon chemical composition through altered soil microbial community composition.Scientific Reports,2016,6:27097.
[24] Santonja M,Rancon A,Fromin N,Baldy V,H?ttenschwiler S,Fernandez C,Montès N,Mirleau P.Plant litter diversity increases microbial abundance,fungal diversity,and carbon and nitrogen cycling in a Mediterranean shrubland.Soil Biology and Biochemistry,2017,111:124- 134.
[25] Palm C A,Sanchez P A.Nitrogen release from the leaves of some tropical legumes as affected by their lignin and polyphenolic contents.Soil Biology and Biochemistry,1991,23(1):83- 88.
[26] Kemp P R,Reynolds J F,Virginia R A,Whitford W G.Decomposition of leaf and root litter of Chihuahuan desert shrubs:effects of three years of summer drought.Journal of Arid Environments,2003,53(1):21- 39.
[27] Potthoff M,Steenwerth K L,Jackson L E,Drenovsky R E,Scow K M,Joergensen R G.Soil microbial community composition as affected by restoration practices in California grassland.Soil Biology and Biochemistry,2006,38(7):1851- 1860.
[28] Jacob M,Leuschner C,Thomas F M.Productivity of temperate broad-leaved forest stands differing in tree species diversity.Annals of Forest Science,2010,67(5):503- 503.
[29] Austin A T,Ballaré C L.Dual role of lignin in plant litter decomposition in terrestrial ecosystems.Proceedings of the National Academy of Sciences of the United States of America,2010,107(10):4618- 4622.
[30] 于雯超,宋晓龙,修伟明,张贵龙,赵建宁,杨殿林.氮素添加对贝加尔针茅草原凋落物分解的影响.草业学报,2014,23(5):49- 60.
[31] 李文亚,邱璇,白龙,杨殿林.氮、磷添加对贝加尔针茅草原凋落物分解的影响.草业学报,2017,26(8):43- 53.
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