Review of the roles of plants and soil microorganisms in regulating ecosystem nutrient cycling
JIANG Jing, SONG Ming-Hua,*
Key Laboratory of Ecosystem Network Observation and Modeling, Chinese Ecosystem Research Network Synthesis Research Center, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China
Above- and below-ground are important components of terrestrial ecosystems. Plants and microorganisms are dependent on each other, and they are important in the linkage between above- and below-ground processes. The relationship between plants and soil microorganisms and the fundamental role played by above- and below-ground feedbacks are important in controlling ecosystem processes and properties. Plant species play a fundamental role in nutrient absorption, nutrient accumulation, nutrient distribution and nutrient return. Soil microorganisms are important in controlling plant nutrient availability and soil quality. Our main objective is to summarize the relationships between plants and microbes, such as facilitation and competition. Plants, as producers, provide nutrients for soil microorganisms via leaf litter and root exudation. Soil microorganisms, as decomposers, break down organic matter and provide nutrients to plants. A wide range of soil microbes form intimate symbiotic associations with plants, and this can stimulate plant productivity by delivering limited nutrients to their host plants. However, both plants and microbes compete for nutrients because plant nutrient uptake and microbial immobilization occur simultaneously. We provide an integrated analysis of effects of plant diversity on soil microbial diversity, as well as direct and indirect effects of soil microbes on plant diversity and productivity. Previously, the mechanisms of plants and microorganisms in regulating ecosystem nutrient cycling have been controversial. Litter chemical composition and diversity should be considered important functional traits that explain the mechanisms. It is clear that interactions between plants and microbes play a fundamental role in maintaining the stability of natural ecosystems. This review elucidates the linkage between aboveground and belowground processes, which have been treated separately in the past.
JIANG Jing, SONG Ming-Hua. Review of the roles of plants and soil microorganisms in regulating ecosystem nutrient cycling. Chinese Journal of Plant Ecology[J], 2010, 34(8): 979-988 DOI:10.3773/j.issn.1005-264x.2010.08.011
Balanced growth in aquatic plants: myth or reality? Phytoplankton use the imbalance between carbon assimilation and biomass production to their strategic advantage
Plants can have positive effects on each other. For example, the accumulation of nutrients, provision of shade, amelioration of disturbance, or protection from herbivores by some species can enhance the performance of neighbouring species. Thus the notion that the distributions and abundances of plant species are independent of other species may be inadequate as a theoretical underpinning for understanding species coexistence and diversity. But there have been no large-scale experiments designed to examine the generality of positive interactions in plant communities and their importance relative to competition. Here we show that the biomass, growth and reproduction of alpine plant species are higher when other plants are nearby. In an experiment conducted in subalpine and alpine plant communities with 115 species in 11 different mountain ranges, we find that competition generally, but not exclusively, dominates interactions at lower elevations where conditions are less physically stressful. In contrast, at high elevations where abiotic stress is high the interactions among plants are predominantly positive. Furthermore, across all high and low sites positive interactions are more important at sites with low temperatures in the early summer, but competition prevails at warmer sites.
ChapmanSK, LangleyJA, HartSC, KochGW (2006).
Plants actively control nitrogen cycling: uncorking the microbial bottleneck
Nitrogen (N) tends to limit plant productivity on young soils; phosphorus (P) becomes increasingly limiting in ancient soils because it gradually disappears through leaching and erosion. Plant traits that are regarded as adaptations to N- and P-limited conditions include mycorrhizas and cluster roots. Mycorrhizas 'scavenge' P from solution or 'mine' insoluble organic N. Cluster roots function in severely P-impoverished landscapes, 'mining' P fixed as insoluble inorganic phosphates. The 'scavenging' and 'mining' strategies of mycorrhizal species without and non-mycorrhizal species with cluster roots, respectively, allow functioning on soils that differ markedly in P availability. Based on recent advances in our understanding of these contrasting strategies of nutrient acquisition, we provide an explanation for the distribution of mycorrhizal species on less P-impoverished soils, and for why, globally, cluster-bearing species dominate on severely P-impoverished, ancient soils, where P sensitivity is relatively common.
Profiling of complex microbial populations by denaturing gradient gel electrophoresis analysis of polymerase chain reaction-amplified genes coding for 16S rRNA
Applied and Environmental Microbiology, 59, 695-700.
Litter decomposition provides the primary source of mineral nitrogen (N) for biological activity in most terrestrial ecosystems. A 10-year decomposition experiment in 21 sites from seven biomes found that net N release from leaf litter is dominantly driven by the initial tissue N concentration and mass remaining regardless of climate, edaphic conditions, or biota. Arid grasslands exposed to high ultraviolet radiation were an exception, where net N release was insensitive to initial N. Roots released N linearly with decomposition and exhibited little net N immobilization. We suggest that fundamental constraints on decomposer physiologies lead to predictable global-scale patterns in net N release during decomposition.
PengQ (彭琴), DongYS (董云社), QiYC (齐玉春) (2008).
Influence of external nitrogen input on key processses of carbon cycle in terrestrial ecosystem
Advances in Earth Science(地球科学进展), 23, 874-883. (in Chinese with English abstract)
The role of endomycorrhizae in revegetation practices in the semi-arid West. I. A comparison of incidence of mycorrhizae in severely disturbed vs. natural environments
Single-strand-conformation polymorphism (SSCP) of DNA, a method widely used in mutation analysis, was adapted to the analysis and differentiation of cultivated pure-culture soil microorganisms and noncultivated rhizosphere microbial communities. A fragment (approximately 400 bp) of the bacterial 16S rRNA gene (V-4 and V-5 regions) was amplified by PCR with universal primers, with one primer phosphorylated at the 5' end. The phosphorylated strands of the PCR products were selectively digested with lambda exonuclease, and the remaining strands were separated by electrophoresis with an MDE polyacrylamide gel, a matrix specifically optimized for SSCP purposes. By this means, reannealing and heteroduplex formation of DNA strands during electrophoresis could be excluded, and the number of bands per organism was reduced. PCR products from 10 of 11 different bacterial type strains tested could be differentiated from each other. With template mixtures consisting of pure-culture DNAs from 5 and 10 bacterial strains, most of the single strains could be detected from such model communities after PCR and SSCP analyses. Purified bands amplified from pure cultures and model communities extracted from gels could be reamplified by PCR, but by this process, additional products were also generated, as detected by further SSCP analysis. Profiles generated with DNAs of rhizosphere bacterial communities, directly extracted from two different plant species grown in the same field site, could be clearly distinguished. This study demonstrates the potential of the selected PCR-single-stranded DNA approach for microbial community analysis.
SmithJL, PaulEA (1990).
The significance of soil microbial biomass estimations
Soil bacterium DNA was isolated by minor modifications of previously described methods. After purification on hydroxyapatite and precipitation with cetylpyridinium bromide, the DNA was sheared in a French press to give fragments with an average molecular mass of 420,000 daltons. After repeated hydroxyapatite purification and precipitation with cetylpyridinium bromide, high-pressure liquid chromatography analysis showed the presence of 2.1% RNA or less, whereas 5-methylcytosine made up 2.9% of the total deoxycytidine content. No other unusual bases could be detected. The hyperchromicity was 31 to 36%, and the melting curve in 1 X SSC (0.15 M NaCl plus 0.015 M sodium citrate) corresponded to 58.3 mol% G+C. High-pressure liquid chromatography analysis of two DNA samples gave 58.6 and 60.8 mol% G+C. The heterogeneity of the DNA was determined by reassociation of single-stranded DNA, measured spectrophotometrically. Owing to the high complexity of the DNA, the reassociation had to be carried out in 6 X SSC with 30% dimethyl sulfoxide added. Cuvettes with a 1-mm light path were used, and the A275 was read. DNA concentrations as high as 950 micrograms ml-1 could be used, and the reassociation rate of Escherichia coli DNA was increased about 4.3-fold compared with standard conditions. C0t1/2 values were determined relative to that for E. coli DNA, whereas calf thymus DNA was reassociated for comparison. Our results show that the major part of DNA isolated from the bacterial fraction of soil is very heterogeneous, with a C0t1/2 about 4,600, corresponding to about 4,000 completely different genomes of standard soil bacteria.(ABSTRACT TRUNCATED AT 250 WORDS)
van der HeijdenMGA, BardgettRD, van StraalenNM (2008).
The unseen majority: soil microbes as drivers of plant diversity and productivity in terrestrial ecosystems
Microbes are the unseen majority in soil and comprise a large portion of life's genetic diversity. Despite their abundance, the impact of soil microbes on ecosystem processes is still poorly understood. Here we explore the various roles that soil microbes play in terrestrial ecosystems with special emphasis on their contribution to plant productivity and diversity. Soil microbes are important regulators of plant productivity, especially in nutrient poor ecosystems where plant symbionts are responsible for the acquisition of limiting nutrients. Mycorrhizal fungi and nitrogen-fixing bacteria are responsible for c. 5-20% (grassland and savannah) to 80% (temperate and boreal forests) of all nitrogen, and up to 75% of phosphorus, that is acquired by plants annually. Free-living microbes also strongly regulate plant productivity, through the mineralization of, and competition for, nutrients that sustain plant productivity. Soil microbes, including microbial pathogens, are also important regulators of plant community dynamics and plant diversity, determining plant abundance and, in some cases, facilitating invasion by exotic plants. Conservative estimates suggest that c. 20 000 plant species are completely dependent on microbial symbionts for growth and survival pointing to the importance of soil microbes as regulators of plant species richness on Earth. Overall, this review shows that soil microbes must be considered as important drivers of plant diversity and productivity in terrestrial ecosystems.
van der HeijdenMGA, BollerT, WiemkenA, SandersIR (1998a).
Different arbuseular mycorrhizal fungi species are potential determinants of plant community structure
Balanced growth in aquatic plants: myth or reality? Phytoplankton use the imbalance between carbon assimilation and biomass production to their strategic advantage
Relationships between plant and soil microorganisms in natural ecosystem (Modified from <xref ref-type="bibr" rid="b36">Leake <i>et al.</i>, 2004</xref>; <xref ref-type="bibr" rid="b67">van der Heijden <i>et al.</i>, 2008</xref>).Fig. 13.1 植物与土壤微生物之间的相互依存关系
植物通过其凋落物和分泌物为土壤微生物提供营养, 导致植物和微生物之间的协同进化, 促进土壤微生物的多样性.比如, 细菌倾向于利用富含碳水化合物和糖类的凋落物, 真菌倾向于利用富含酚类的凋落物(Bardgett et al., 1993, 1996, 1997); 白三叶草(Trifolium repens)根际土壤中的微生物数量和活性与植物根系的长度和密度也高度相关(Schortemeyer et al., 1997); 草地植被生长的根系可增加土壤中原碳的衰变速率(Personeni et al., 2005). William Hamilton和Frank (2001)的研究表明, 短时间内, 被食草动物啃食的植物可提供更多的碳给根围, 对微生物活性有促进作用, 进而提高植物的氮利用率和植物生产力.寄生植物在自然和人为生态系统中都普遍存在, 在欧洲和南美草地生态系统广泛生长的根部半寄生植物小佛甲草(Rhinanthus minor)强烈地影响地上群落性质, 改变根的生长状况、根周转率以及碳供给, 从而影响分解者有机体活性, 氮矿化速率明显增加(Bardgett et al., 2006). ...
... Relationships between plant and soil microorganisms in natural ecosystem (Modified from Leake et al., 2004; van der Heijden et al., 2008). Fig. 13.1 植物与土壤微生物之间的相互依存关系
植物通过其凋落物和分泌物为土壤微生物提供营养, 导致植物和微生物之间的协同进化, 促进土壤微生物的多样性.比如, 细菌倾向于利用富含碳水化合物和糖类的凋落物, 真菌倾向于利用富含酚类的凋落物(Bardgett et al., 1993, 1996, 1997); 白三叶草(Trifolium repens)根际土壤中的微生物数量和活性与植物根系的长度和密度也高度相关(Schortemeyer et al., 1997); 草地植被生长的根系可增加土壤中原碳的衰变速率(Personeni et al., 2005). William Hamilton和Frank (2001)的研究表明, 短时间内, 被食草动物啃食的植物可提供更多的碳给根围, 对微生物活性有促进作用, 进而提高植物的氮利用率和植物生产力.寄生植物在自然和人为生态系统中都普遍存在, 在欧洲和南美草地生态系统广泛生长的根部半寄生植物小佛甲草(Rhinanthus minor)强烈地影响地上群落性质, 改变根的生长状况、根周转率以及碳供给, 从而影响分解者有机体活性, 氮矿化速率明显增加(Bardgett et al., 2006). ...
Application of ectomycorrhiza fungi in young Pinus tabulaeformis Carr. forest
1
2001
... 此外, 植物与土壤微生物共生是自然界中普遍存在的生物学现象.自然群落中90%以上的陆生植物能与泡囊-丛枝菌根真菌(vesicular-arbuscular mycorrhizal fungi, VAMF)共生形成菌根(Reeves et al., 1979; 刘润进和李晓林, 2000; 张英等, 2003).研究表明, 菌根菌在自然界养分循环中的作用, 除了能通过根外菌丝将土壤中的矿质元素、水分等输送给植物吸收利用, 提高植物成活率, 促进植物生长(韩桂云等, 2002), 还能提高植物的抗逆性和抗病性(弓明钦等, 1999).林鹤鸣等(2001)研究表明, 在土壤贫瘠的山地条件下, 接种外生菌根真菌, 可以改善土壤中微生物的种群结构, 提高土壤中细菌、真菌、放线菌的数量, 其中真菌增加7.3倍, 林木的菌根侵染率由20%提高到75%, 进而促进油松(Pinus tabulaeformis)人工林的生长.当前, 国际上有关菌根方面的研究逐渐升温, 亦有数篇文章在《Science》、《Nature》等刊物上发表.植物与真菌之间的互利共生关系能提高植物的耐热性(Redman et al., 2002).鉴于美国东北部森林生态系统Ca严重流失的情况, Blum等(2002)研究发现外生菌根的树种更能利用有磷灰石风化的Ca, 表明菌根可能直接风化磷灰石和吸收释放出的Ca2+, 为植物提供钙源.Hodge (2003)发现, 在植物种间存在竞争时, 接种丛枝菌根可促进植物对氮元素的吸收.Wolfe等(2005)的试验同样表明, 在柳兰(Chamerion angustifolium)根部植入丛枝菌根真菌, 将大大提高植物被授粉的几率.在养分缺乏的生态系统中, 植物共生体吸收限制性养分来调节植物生产力(van der Heijden et al., 2008).植物共生体菌根真菌, 能增加限制性氮、磷的利用率, 对植物生产力有正反馈作用(Lambers et al., 2008).因此, 菌根菌的多样性与丰度对维持植物的多样性及生态系统的稳定性和生产力具有重要意义(van der Heijden et al., 1998a, 1998b; 杨维平, 2002). ...
1
2000
... 此外, 植物与土壤微生物共生是自然界中普遍存在的生物学现象.自然群落中90%以上的陆生植物能与泡囊-丛枝菌根真菌(vesicular-arbuscular mycorrhizal fungi, VAMF)共生形成菌根(Reeves et al., 1979; 刘润进和李晓林, 2000; 张英等, 2003).研究表明, 菌根菌在自然界养分循环中的作用, 除了能通过根外菌丝将土壤中的矿质元素、水分等输送给植物吸收利用, 提高植物成活率, 促进植物生长(韩桂云等, 2002), 还能提高植物的抗逆性和抗病性(弓明钦等, 1999).林鹤鸣等(2001)研究表明, 在土壤贫瘠的山地条件下, 接种外生菌根真菌, 可以改善土壤中微生物的种群结构, 提高土壤中细菌、真菌、放线菌的数量, 其中真菌增加7.3倍, 林木的菌根侵染率由20%提高到75%, 进而促进油松(Pinus tabulaeformis)人工林的生长.当前, 国际上有关菌根方面的研究逐渐升温, 亦有数篇文章在《Science》、《Nature》等刊物上发表.植物与真菌之间的互利共生关系能提高植物的耐热性(Redman et al., 2002).鉴于美国东北部森林生态系统Ca严重流失的情况, Blum等(2002)研究发现外生菌根的树种更能利用有磷灰石风化的Ca, 表明菌根可能直接风化磷灰石和吸收释放出的Ca2+, 为植物提供钙源.Hodge (2003)发现, 在植物种间存在竞争时, 接种丛枝菌根可促进植物对氮元素的吸收.Wolfe等(2005)的试验同样表明, 在柳兰(Chamerion angustifolium)根部植入丛枝菌根真菌, 将大大提高植物被授粉的几率.在养分缺乏的生态系统中, 植物共生体吸收限制性养分来调节植物生产力(van der Heijden et al., 2008).植物共生体菌根真菌, 能增加限制性氮、磷的利用率, 对植物生产力有正反馈作用(Lambers et al., 2008).因此, 菌根菌的多样性与丰度对维持植物的多样性及生态系统的稳定性和生产力具有重要意义(van der Heijden et al., 1998a, 1998b; 杨维平, 2002). ...
Nitrogen cycling in a northern hardwood forest: Do species matter?
Patterns of carbon, nitrogen and phosphorus dynamics in decomposing foliar litter in Canadian forests
1
2006
... 虽然不能完全确认究竟是植物还是土壤微生物在调控生态系统养分循环过程中起关键作用, 但可以肯定的是, 植物与土壤微生物在这个生态系统中共同调控着土壤养分的有效性与分配.从植物凋落物中释放的N常常被联系到C/N比或凋落物初始N浓度(C/N比为25-30, 初始N浓度为20 mg∙g-1作为净累积或净N释放的阈值) (Berg & Laskowski, 2006; Moore et al., 2006), 而C/N比就随着生态系统和所研究的物种的不同而变化.2007年《Science》报道了在全球6个主要生物群区开展的不同质量凋落物(氮含量由低到高, 0.39%-1.98%)分解的实验, 结果表明: 净N固持与释放的格局与物种叶片凋落物的初始N浓度有关(Parton et al., 2007).2008年《Science》报道了另外一项凋落物分解研究结果, 该结果肯定了净N释放与固持依赖于分解者与基质中的C/N比这一结论, 但它指出, 分解者可通过降低自身的碳利用效率来利用具有低初始N浓度的凋落物(Manzoni et al., 2008).这种格局表明分解者群落能通过降低自身的C利用效率而降低凋落物关键的C/N比来适应部分低氮基质.因此, 只有深入研究植物与土壤微生物之间的作用与反馈, 才能从机理上揭示植物与土壤微生物在调控生态过程中的作用机制. ...
Profiling of complex microbial populations by denaturing gradient gel electrophoresis analysis of polymerase chain reaction-amplified genes coding for 16S rRNA
1
1993
... 陆地生态系统的地上、地下是相互联系的, 传统研究往往过多地关注地上生物群落, 而忽略了地下生物群落在陆地生态系统中的重要作用(Bardgett et al., 2005), 地下生物群落及其生态过程一直被认为是“黑匣子”(black box), 因而地下生物群落成为生态系统功能研究中最不确定的部分(Reynolds et al., 2003).近20年来分子生物学方法和技术应用于土壤微生物群落调查与功能评价方面取得了很大进展(Torsvik, 1980; Torsvik et al., 1990; Muyzer et al., 1993; Schwieger & Tebbe, 1998; Ogram, 2000), 越来越多的研究关注于地上、地下生态过程之间的作用与反馈(Porazinska et al., 2003; Bardgett et al., 2005), 这使得通过地上和地下生态过程的结合从整体上探讨它们在调控生态系统结构和功能中的作用成为可能.植物与土壤微生物之间的作用与反馈是生态系统地上、地下结合的重要纽带, 因此, 揭示二者在养分循环中的调控机制可以使我们深入理解生态系统稳定性维持的内在机制. ...
Soil molecular microbial ecology at age 20: methodological challenges for the future
1
2000
... 陆地生态系统的地上、地下是相互联系的, 传统研究往往过多地关注地上生物群落, 而忽略了地下生物群落在陆地生态系统中的重要作用(Bardgett et al., 2005), 地下生物群落及其生态过程一直被认为是“黑匣子”(black box), 因而地下生物群落成为生态系统功能研究中最不确定的部分(Reynolds et al., 2003).近20年来分子生物学方法和技术应用于土壤微生物群落调查与功能评价方面取得了很大进展(Torsvik, 1980; Torsvik et al., 1990; Muyzer et al., 1993; Schwieger & Tebbe, 1998; Ogram, 2000), 越来越多的研究关注于地上、地下生态过程之间的作用与反馈(Porazinska et al., 2003; Bardgett et al., 2005), 这使得通过地上和地下生态过程的结合从整体上探讨它们在调控生态系统结构和功能中的作用成为可能.植物与土壤微生物之间的作用与反馈是生态系统地上、地下结合的重要纽带, 因此, 揭示二者在养分循环中的调控机制可以使我们深入理解生态系统稳定性维持的内在机制. ...
Global-scale similarities in nitrogen release patterns during long-term decomposition
1
2007
... 虽然不能完全确认究竟是植物还是土壤微生物在调控生态系统养分循环过程中起关键作用, 但可以肯定的是, 植物与土壤微生物在这个生态系统中共同调控着土壤养分的有效性与分配.从植物凋落物中释放的N常常被联系到C/N比或凋落物初始N浓度(C/N比为25-30, 初始N浓度为20 mg∙g-1作为净累积或净N释放的阈值) (Berg & Laskowski, 2006; Moore et al., 2006), 而C/N比就随着生态系统和所研究的物种的不同而变化.2007年《Science》报道了在全球6个主要生物群区开展的不同质量凋落物(氮含量由低到高, 0.39%-1.98%)分解的实验, 结果表明: 净N固持与释放的格局与物种叶片凋落物的初始N浓度有关(Parton et al., 2007).2008年《Science》报道了另外一项凋落物分解研究结果, 该结果肯定了净N释放与固持依赖于分解者与基质中的C/N比这一结论, 但它指出, 分解者可通过降低自身的碳利用效率来利用具有低初始N浓度的凋落物(Manzoni et al., 2008).这种格局表明分解者群落能通过降低自身的C利用效率而降低凋落物关键的C/N比来适应部分低氮基质.因此, 只有深入研究植物与土壤微生物之间的作用与反馈, 才能从机理上揭示植物与土壤微生物在调控生态过程中的作用机制. ...
Influence of external nitrogen input on key processses of carbon cycle in terrestrial ecosystem
Thermotolerance generated by plant/fungal symbiosis
1
2002
... 此外, 植物与土壤微生物共生是自然界中普遍存在的生物学现象.自然群落中90%以上的陆生植物能与泡囊-丛枝菌根真菌(vesicular-arbuscular mycorrhizal fungi, VAMF)共生形成菌根(Reeves et al., 1979; 刘润进和李晓林, 2000; 张英等, 2003).研究表明, 菌根菌在自然界养分循环中的作用, 除了能通过根外菌丝将土壤中的矿质元素、水分等输送给植物吸收利用, 提高植物成活率, 促进植物生长(韩桂云等, 2002), 还能提高植物的抗逆性和抗病性(弓明钦等, 1999).林鹤鸣等(2001)研究表明, 在土壤贫瘠的山地条件下, 接种外生菌根真菌, 可以改善土壤中微生物的种群结构, 提高土壤中细菌、真菌、放线菌的数量, 其中真菌增加7.3倍, 林木的菌根侵染率由20%提高到75%, 进而促进油松(Pinus tabulaeformis)人工林的生长.当前, 国际上有关菌根方面的研究逐渐升温, 亦有数篇文章在《Science》、《Nature》等刊物上发表.植物与真菌之间的互利共生关系能提高植物的耐热性(Redman et al., 2002).鉴于美国东北部森林生态系统Ca严重流失的情况, Blum等(2002)研究发现外生菌根的树种更能利用有磷灰石风化的Ca, 表明菌根可能直接风化磷灰石和吸收释放出的Ca2+, 为植物提供钙源.Hodge (2003)发现, 在植物种间存在竞争时, 接种丛枝菌根可促进植物对氮元素的吸收.Wolfe等(2005)的试验同样表明, 在柳兰(Chamerion angustifolium)根部植入丛枝菌根真菌, 将大大提高植物被授粉的几率.在养分缺乏的生态系统中, 植物共生体吸收限制性养分来调节植物生产力(van der Heijden et al., 2008).植物共生体菌根真菌, 能增加限制性氮、磷的利用率, 对植物生产力有正反馈作用(Lambers et al., 2008).因此, 菌根菌的多样性与丰度对维持植物的多样性及生态系统的稳定性和生产力具有重要意义(van der Heijden et al., 1998a, 1998b; 杨维平, 2002). ...
The role of endomycorrhizae in revegetation practices in the semi-arid West. I. A comparison of incidence of mycorrhizae in severely disturbed vs. natural environments
1
1979
... 此外, 植物与土壤微生物共生是自然界中普遍存在的生物学现象.自然群落中90%以上的陆生植物能与泡囊-丛枝菌根真菌(vesicular-arbuscular mycorrhizal fungi, VAMF)共生形成菌根(Reeves et al., 1979; 刘润进和李晓林, 2000; 张英等, 2003).研究表明, 菌根菌在自然界养分循环中的作用, 除了能通过根外菌丝将土壤中的矿质元素、水分等输送给植物吸收利用, 提高植物成活率, 促进植物生长(韩桂云等, 2002), 还能提高植物的抗逆性和抗病性(弓明钦等, 1999).林鹤鸣等(2001)研究表明, 在土壤贫瘠的山地条件下, 接种外生菌根真菌, 可以改善土壤中微生物的种群结构, 提高土壤中细菌、真菌、放线菌的数量, 其中真菌增加7.3倍, 林木的菌根侵染率由20%提高到75%, 进而促进油松(Pinus tabulaeformis)人工林的生长.当前, 国际上有关菌根方面的研究逐渐升温, 亦有数篇文章在《Science》、《Nature》等刊物上发表.植物与真菌之间的互利共生关系能提高植物的耐热性(Redman et al., 2002).鉴于美国东北部森林生态系统Ca严重流失的情况, Blum等(2002)研究发现外生菌根的树种更能利用有磷灰石风化的Ca, 表明菌根可能直接风化磷灰石和吸收释放出的Ca2+, 为植物提供钙源.Hodge (2003)发现, 在植物种间存在竞争时, 接种丛枝菌根可促进植物对氮元素的吸收.Wolfe等(2005)的试验同样表明, 在柳兰(Chamerion angustifolium)根部植入丛枝菌根真菌, 将大大提高植物被授粉的几率.在养分缺乏的生态系统中, 植物共生体吸收限制性养分来调节植物生产力(van der Heijden et al., 2008).植物共生体菌根真菌, 能增加限制性氮、磷的利用率, 对植物生产力有正反馈作用(Lambers et al., 2008).因此, 菌根菌的多样性与丰度对维持植物的多样性及生态系统的稳定性和生产力具有重要意义(van der Heijden et al., 1998a, 1998b; 杨维平, 2002). ...
Grassroots ecology: plant-microbe-soil interactions as drivers of plant community structure and dynamics
1
2003
... 陆地生态系统的地上、地下是相互联系的, 传统研究往往过多地关注地上生物群落, 而忽略了地下生物群落在陆地生态系统中的重要作用(Bardgett et al., 2005), 地下生物群落及其生态过程一直被认为是“黑匣子”(black box), 因而地下生物群落成为生态系统功能研究中最不确定的部分(Reynolds et al., 2003).近20年来分子生物学方法和技术应用于土壤微生物群落调查与功能评价方面取得了很大进展(Torsvik, 1980; Torsvik et al., 1990; Muyzer et al., 1993; Schwieger & Tebbe, 1998; Ogram, 2000), 越来越多的研究关注于地上、地下生态过程之间的作用与反馈(Porazinska et al., 2003; Bardgett et al., 2005), 这使得通过地上和地下生态过程的结合从整体上探讨它们在调控生态系统结构和功能中的作用成为可能.植物与土壤微生物之间的作用与反馈是生态系统地上、地下结合的重要纽带, 因此, 揭示二者在养分循环中的调控机制可以使我们深入理解生态系统稳定性维持的内在机制. ...
An exotic tree alters decomposition and nutrient cycling in a Hawaiian montane forest
