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1.
Pollution induced community tolerance (PICT) has been suggested as an end-point measurement less affected by confounding environmental factors compared to standard methods of microbial growth, activity and community composition. We evaluated the use of PICT to determine Cu toxicity in vineyard soils polluted with Cu based fungicides (25-1120 mg Cu kg−1). These soils also varied in pH (4.3-7.3), organic C (0.31-6.91%) and texture (14-56% silt). PICT was estimated as bacterial community tolerance to Cu measured by the [3H]leucine incorporation method. Bacterial tolerance to Cu increased 9 times in the most polluted compared to the unpolluted soils. Cu tolerance was also affected to a minor degree by pH, organic C and soil texture. Lower bacterial tolerance was found in soils with high pH and organic C, probably due to Cu becoming less bioavailable in soils with high pH and organic C content. The silt content appeared to increase bacterial tolerance, probably due to fine soil particles decreasing Cu bioavailability during the PICT detection phase. Despite the effects of other environmental factors, the main determinant of increased bacterial community tolerance to Cu was the pollution level. PICT measured with the leucine incorporation technique thus appears to be a sensitive and stable concept to evaluate toxic impacts, unless soils with very different pH, organic C or texture are studied.  相似文献   

2.
In a study to assess the sustainable use of sewage sludge application to land, the long-term effect of Zn and Cu contaminated sludge additions on the structure of the bacterial communities (using T-RFLP analysis) and their tolerance to additional metal exposure through pollution-induced community tolerance (PICT) assays was assessed. This used two soils that received metal-rich sludge cake (SC), liquid sludge (LS) or metal salts (MS) additions more than 10 years previously. Soil type had the predominant influence on bacterial community structure and PICT. The source of the metal contamination also had a large influence on community structure and PICT, greater than the effects due to metal concentrations. Nevertheless, in both Zn and Cu contaminated soils, PICT was observed and decreased in the order MS > LS > SC. Within a metal source and site, there was evidence of increased PICT with increasing Zn or Cu contamination, however few differences were significant as a result of high variability between sample replicates. These results highlight the importance of considering soil physico-chemical properties and the source of metal contamination as well as total metal concentrations when considering the long-term effects of metals on soil microbial communities. Further, the matrix that a metal is associated with prior to addition may play an important factor in determining levels of toxicity. This could have consequences for the interpretation and use of data from metal spiking experiments when considering metal limits for sludge application to land.  相似文献   

3.
Monomethyl-mercury is one of the most toxic compounds. Methylation of Hg usually appears under anoxic conditions. In Swiss forest soils, methyl-Hg concentrations of up to 3 μg kg−1 soil dw have been observed, but the impact of methyl-Hg on soil microorganisms have rarely been examined so far. In this study, we investigated the effect of increasing concentrations of methyl-Hg (0, 5, 20, 90 μg kg−1 soil dw) on the microbial communities in various forest soils differing in their physico-chemical properties. Experiments were conducted in microcosms under controlled conditions and the basal respiration (BR), the microbial biomass carbon (MBC) and the bacterial and fungal community structures using T-RFLP-profiling were investigated. BR was significantly affected by methyl-Hg. In general, the BR increased with increasing methyl-Hg concentrations, whereas the MBC was significantly reduced. Bacterial communities were more sensitive to methyl-Hg than fungal communities. In five out of seven soils, the bacterial community structures differed significantly between the treatments whereas the fungal communities did not. The impact of methyl-Hg on the soil bacterial communities was site specific. In one soil, a methyl-Hg concentration of already 5 μg kg−1 soil dw significantly affected the relative abundance of 13% bacterial operational taxonomic units (OTU), whereas in other soils concentrations of even 90 μg kg−1 soil dw rarely affected the abundance of OTUs. In this study, for the first time, the impact of methyl-Hg on soil bacterial and fungal communities in forest soils was assessed. We showed that its impact strongly depends on the physico-chemical conditions of the soil and that bacterial communities were more sensitive to methyl-Hg than fungi.  相似文献   

4.
The microbial activity and bacterial community structure were investigated in two types of peat soil in a temperate marsh. The first, a drained grassland fen soil, has a neutral pH with partially degraded peat in the upper oxic soil horizons (16% soil organic carbon). The second, a bog soil, was sampled in a swampy forest and has a very high soil organic carbon content (45%), a low pH (4.5), and has occasional anoxic conditions in the upper soil horizons due to the high water table level. The microbial activity in the two soils was measured as the basal and substrate-induced respiration (SIR). Unexpectedly, the SIR (μl CO2 g−1 dry soil) was higher in the bog than in the fen soil, but lower when CO2 production was expressed per volume of soil. This may be explained by the notable difference in the bulk densities of the two soils. The bacterial communities were assessed by terminal restriction fragment length polymorphism (T-RFLP) profiling of 16S rRNA genes and indicated differences between the two soils. The differences were determined by the soil characteristics rather than the season in which the soil was sampled. The 16S rRNA gene libraries, constructed from the two soils, revealed high proportions of sequences assigned to the Acidobacteria phylum. Each library contained a distinct set of phylogenetic subgroups of this important group of bacteria.  相似文献   

5.
An 8 year study to investigate the effects of Zn-spiked sewage sludge additions on the microbial community structure and microbial processes was carried out in a field soil under pasture. The microbial community structure was evaluated using a combination of multiplex-terminal restriction fragment length polymorphism (M-TRFLP) and T-RFLP fingerprinting approaches. Soil respiration, microbial biomass and enzymatic activities were measured as indicators of soil microbial processes. Changes in the microbial community structure, with Zn additions were evident in all the microbial groups investigated (bacteria, fungi, archaea, actinobacteria and rhizobia/agrobacteria). The fungal community showed the greatest response to Zn additions compared to the other microbial communities measured. The relative abundance of several fungal terminal restriction fragments (TRFs) significantly increased in high Zn treated treatments, at the expense of others, some of which were lost from T-RFLP profiles completely. These results indicate that metal-spiked sludge application can have long-lasting impacts on the composition of the microbial community in pasture soils. Despite notable changes in community structure there was no significant long-term impact of Zn-spiked sludge applications on microbial respiration, biomass or enzyme activities.  相似文献   

6.
Fen peatlands are specific wetland ecosystems containing high soil organic carbon (SOC). There is a general lack of knowledge about the microbial communities that abound in these systems. We examined the microbial activity and community structure in two fen soils differing in SOC content sampled from the Ljubljana Marsh under different seasonal conditions. Substrate-induced respiration and dehydrogenase activity were used as indicators of total microbial activity. Both methods indicated higher microbial activities in the fen soil with the higher SOC content on all dates of sampling. To determine whether the differences in microbial activity were associated with differences in the microbial community structures, terminal restriction fragment length polymorphism (T-RFLP) of bacterial 16S rRNA genes was performed. Comparison of the T-RFLP profiles revealed very similar community structures in both fens and in the two seasonal extremes investigated. This suggested a stable community structure in the two fens, which is not affected by the SOC content or seasonal variation. In addition, a bacterial 16S ribosomal RNA gene based clone library was prepared from the fen soil with the higher SOC content. Out of 114 clones analysed, approximately 53% belonged to the Proteobacteria, 23% to the Acidobacteria, 21% to a variety of other taxa, and less than 3% were affiliated with the Firmicutes.  相似文献   

7.
Soil microbial communities can develop trace metal tolerance upon soil contamination with corresponding metals. A few studies have reported co-tolerance in such cases, i.e. tolerance to other metals than those to which the microbial community had been exposed to. This study was set-up to test for co-tolerance of nitrifying communities to zinc (Zn) and copper (Cu) and to relate tolerances to shifts in community structure using amoA AOB (ammonia oxidizing bacteria) DGGE. Seven sets of soils, each representing a Cu or Zn contamination gradient were sampled from four locations. At two locations, both Cu and Zn had been added as single contaminants. Increased Zn and Cu tolerance of the nitrifying communities was consistently observed in response to corresponding soil contamination. Co-tolerance to Zn was obtained in two of the three Cu gradients and that to Cu in one of the four Zn gradients. DGGE analysis and sequencing showed that contamination with either Zn or Cu selected for identical AOB phylotypes in soils at one location but not at the other location. The nitrifying community structures in soils from different locations did not become more similar upon Zn exposure than those in corresponding uncontaminated soils. Hence, trace metal tolerance development was not due to the emergence of specific AOB phylotypes, but due to the emergence of different AOB phylotypes bearing tolerance mechanisms for Zn, Cu or both metals.  相似文献   

8.
Arctic soil microorganisms remain active at ecologically relevant rates in frozen soils. We used bromodeoxyuridine (BrdU) labeling and terminal restriction fragment length polymorphism (T-RFLP) analysis of 16S rRNA gene amplicons to examine active bacterial communities in two Alaskan tundra soils collected in summer and winter of 2005. Active community T-RFLP profiles were compared to total community profiles to determine if active bacteria were a subset of the total community. In shrub soils, active bacteria communities differed in composition between summer and winter, and winter-active bacterial taxa were not detected in the total community, suggesting that they are likely rare within the overall community. In contrast, tussock tundra soil contained more bacterial taxa that were active in both summer and winter and also represented a large portion of the total community. Using in silico digest of a sequence library from this site, we attempted to identify the dominant organisms in our samples. Our previous research suggested that the total microbial community was stable throughout the year, but this new study suggests that the active community is more dynamic seasonally. In general, only a subset of the total community was growing at a given time. This temporal niche partitioning may contribute to the high diversity of microbial communities in soils. Understanding which taxa contribute to microbial function under different conditions is the next frontier in microbial ecology and linking composition to biogeochemical cycling.  相似文献   

9.
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10.
In arid and semi-arid ecosystems, salinization is a major threat to the productivity of agricultural land. While the influence of other physical and chemical environmental factors on decomposer microorganisms have been intensively studied in soil, the influence of salinity has been less exhaustively assessed. We investigated the influence of soil salinity on soil bacterial communities in soils covering a range of salt levels. We assessed tolerance of the bacterial communities from Libyan agricultural soils forming a salinity gradient to salt (NaCl), by extracting bacterial communities and instantaneously monitoring the concentration-response to added NaCl with the Leucine incorporation technique for bacterial growth. To maximise our ability to detect differences in bacterial salt tolerance between the soils, we also repeated the assessment of bacterial growth tolerance after one month incubation with 1 or 2% added organic matter additions to stimulate microbial growth levels. We could establish clear concentration-response relationships between bacterial growth and soil salinity, demonstrating an accurate assessment of bacterial tolerance. The in situ soil salinity in the studied soils ranged between 0.64 and 2.73 mM Na (electrical conductivities of 0.74-4.12 mS cm−1; cation exchange capacities of 20-37 mmolc kg−1) and the bacterial tolerance indicated by the concentration inhibiting 50% of the bacterial growth (EC50) varied between 30 and 100 mM Na or between electrical conductivities of 3.0 and 10.7 mS cm−1. There was no relationship between in situ soil salinity and the salt tolerance of the soil bacterial communities. Our results suggest that soil salinity was not a decisive factor for bacterial growth, and thus for structuring the decomposer community, in the studied soils.  相似文献   

11.
The main objective of this study was to assess the impact of the application of an antagonistic strain of Trichoderma atroviride on the native microbial soil communities. The structures of the fungal and bacterial communities were assessed by T-RFLP (terminal restriction fragment length polymorphism) method, based on T-RFLP analysis of 18S and 16S rRNA genes, respectively. Results showed that the introduction of the strain I-1237 into two soils slightly modified the microbial diversity, only for a short period of time. Nine months post-inoculation resilience took place, resulting in similar structures of the fungal and bacterial communities in the inoculated and control soils.  相似文献   

12.
Afforestation and deforestation are key land-use changes across the world, and are considered to be dominant factors controlling ecosystem functioning and biodiversity. However, the responses of soil microbial communities to these land-use changes are not well understood. Because changes in soil microbial abundance and community structure have consequences for nutrient cycling, C-sequestration and long-term sustainability, we investigated impacts of land-use change, age of stand and soil physico-chemical properties on fungal and bacterial communities and their metabolic activities. This study was carried out at four sites in two geographical locations that were afforested on long-established pastures with Pinus radiata D. Don (pine). Two of the sites were on volcanic soils and two on non-volcanic soils and stand age ranged from 5 to 20 y. Microbial communities were analysed by biochemical (phospho-lipid fatty acids; PLFA) and molecular (multiplex-terminal restriction fragment length polymorphism; M-TRFLP) approaches. Both site and stand age influenced microbial properties, with changes being least detectable in the 5-y-old stand. Land use was a key factor influencing soil metabolic activities as measured by physiological profiling using MicroResp. Pasture soils had higher microbial biomass (P < 0.001), and metabolic activities (P < 0.001), and basal respiration rates were up to 2.8-times higher than in the pine soils. Microbial abundance analysis by PLFA showed that the fungal to bacterial ratio was higher in the pine soils (P < 0.01). Community analysis suggested that soil bacterial communities were more responsive to site (principal component 1; P < 0.001) than to land use (principal component 5; P < 0.001). In contrast, the fungal community was more affected by land-use change (principal component 1; P < 0.001) than by site, although site still had some influence on fungal community structure (principal component 2; P < 0.001). Redundancy analysis also suggested that bacterial and fungal communities responded differently to various soil abiotic properties, land-use change and location of sites. Overall, our results indicate that the change in land use from pasture to P. radiata stands had a direct impact on soil fungal communities but an indirect effect, through its effects on soil abiotic properties, on bacterial communities. Most of the changes in bacterial communities could be explained by altered soil physico-chemical properties associated with afforestation of pastures.  相似文献   

13.
Anaerobic digestion of organic materials generates residues of differing chemical composition compared to undigested animal manures, which may affect the soil microbial ecosystem differently when used as fertilizers. This study investigated the effects of two biogas residues (BR-A and BR-B) and cattle slurry (CS) applied at rates corresponding to 70 kg NH4+-N ha−1 on bacterial community structure and microbial activity in three soils of different texture (a sandy, a clay and an organic clay soil). 16S rRNA genes were targeted in PCR reactions and bacterial community profiles visualized using terminal restriction fragment length polymorphism. General microbial activity was measured as basal respiration (B-resp), substrate-induced respiration (SIR), specific growth rate (μSIR), metabolic quotient (qCO2) and nitrogen mineralization capacity (NMC). Non-metric multidimensional scaling analysis visualized shifts in bacterial community structure related to microbial functions. There were significant differences in bacterial community structure after 120 days of incubation (+20 °C at 70% of WHC) between non-amended (control) and amended soils, especially in the sandy soil, where CS caused a more pronounced shift than biogas residues. Terminal-restriction fragment (TRF) 307, the predominant peak in CS-amended sandy soil, was identified as possibly Bacillus or Streptococcus. TRF 226, the dominant peak in organic soil amended with BR-B, was classified as Rhodopseudomonas. B-resp significantly increased and SIR decreased in all amendments to organic soil compared with the control, potentially indicating decreased efficiency of heterotrophic microorganisms to convert organic carbon into microbial biomass. This was also reflected in an elevated qCO2 in the organic soil. The μSIR level was higher in the sandy soil amended with BR-A than with BR-B or CS, indicating a shift toward species capable of rapidly utilizing glucose. NMC was significantly elevated in the clay and organic soils amended with BR-A and BR-B and in the sandy soil amended with BR-B and CS. Thus, biogas residues and cattle slurry had different effects on the bacterial community structure and microbial activity in the three soils. However, the effects of biogas residues on microbial activities were comparable in magnitude to those of cattle slurry and the bacterial community structure was less affected. Therefore, we do not see any reason not to recommend using biogas residues as fertilizers based on the results presented.  相似文献   

14.
《Applied soil ecology》2007,37(2-3):147-155
A number of studies have reported species specific selection of microbial communities in the rhizosphere by plants. It is hypothesised that plants influence microbial community structure in the rhizosphere through rhizodeposition. We examined to what extent the structure of bacterial and fungal communities in the rhizosphere of grasses is determined by the plant species and different soil types. Three grass species were planted in soil from one site, to identify plant-specific influences on rhizosphere microbial communities. To quantify the soil-specific effects on rhizosphere microbial community structure, we planted one grass species (Lolium perenne L.) into soils from three contrasting sites. Rhizosphere, non-rhizosphere (bulk) and control (non-planted) soil samples were collected at regular intervals, to examine the temporal changes in soil microbial communities. Rhizosphere soil samples were collected from both root bases and root tips, to investigate root associated spatial influences. Both fungal and bacterial communities were analysed by terminal restriction fragment length polymorphism (TRFLP). Both bacterial and fungal communities were influenced by the plant growth but there was no evidence for plant species selection of the soil microbial communities in the rhizosphere of the different grass species. For both fungal and bacterial communities, the major determinant of community structure in rhizospheres was soil type. This observation was confirmed by cloning and sequencing analysis of bacterial communities. In control soils, bacterial composition was dominated by Firmicutes and Actinobacteria but in the rhizosphere samples, the majority of bacteria belonged to Proteobacteria and Acidobacteria. Bacterial community compositions of rhizosphere soils from different plants were similar, indicating only a weak influence of plant species on rhizosphere microbial community structure.  相似文献   

15.
In soils, the microbially mediated decomposition of plant residue is a key process with wide ranging effects on ecosystem functioning and stability. Understanding the impact of contamination on this process is of high importance. We investigated the effects of long-term (6 years) copper exposure on the capacity of soil microbiota to decompose newly added resources; dried and ground Medicago truncatula stubble. In addition, the effects on the microbial community structure across the three domains were explored using polymerase chain reaction–denaturing gradient gel electrophoresis rRNA gene profiling. Ecological distances in community structure between treatments was calculated (Kulczynski) and effects tested using PERMANOVA. Clear dose–response relationships were present between microbial respiration (CO2 evolution) and soil Cu level in soils receiving medic, but not under basal conditions (i.e., no medic added). These show that relatively labile forms of C are needed to drive microbial ecotoxicological responses and that microbial adaptation to the presence of Cu in the soils—after >6 years exposure—was functionally limited. Bacterial, archaeal and fungal communities showed significant (P < 0.05) levels of structural change in soils across the Cu gradient, demonstrating that species replacement had occurred following strong selective pressure. Addition of medic resources to the soils caused significant shifts in the bacterial and archaeal community structure (P < 0.001), which occurred across the entire range of soil Cu levels. For the fungal community, a significant interaction effect was present between Cu and medic addition (P = 0.002). At low Cu levels, medic addition caused large shifts in community structure, but this was negligible under high Cu levels. This was reflected in significant changes in the level of community structural dispersion at low compared with high Cu levels. As such, we show that Cu limits the capacity of soil fungal communities to rapidly respond to new resource capture. Given the primary role of soil fungi in plant material decomposition, this may have wide ranging impacts on wider ecosystem processes including nutrient cycling, trophic interactions, food web stability and energy transfer.  相似文献   

16.
Soil microbial communities were examined in a chronosequence of four different land-use treatments at the Konza Prairie Biological Station, Kansas. The time series comprised a conventionally tilled cropland (CTC) developed on former prairie soils, two restored grasslands that were initiated on former agricultural soils in 1998 (RG98) and 1978 (RG78), and an annually burned native tallgrass prairie (BNP), all on similar soil types. In addition, an unburned native tallgrass prairie (UNP) and another grassland restored in 2000 (RG00) on a different soil type were studied to examine the effect of long-term fire exclusion vs. annual burning in native prairie and the influence of soil type on soil microbial communities in restored grasslands. Both 16S rRNA gene clone libraries and phospholipid fatty acid analyses indicated that the structure and composition of bacterial communities in the CTC soil were significantly different from those in prairie soils. Within the time series, soil physicochemical characteristics changed monotonically. However, changes in the microbial communities were not monotonic, and a transitional bacterial community formed during restoration that differed from communities in either the highly disturbed cropland or the undisturbed original prairie. The microbial communities of RG98 and RG00 grasslands were also significantly different even though they were restored at approximately the same time and were managed similarly; a result attributable to the differences in soil type and associated soil chemistry such as pH and Ca. Burning and seasonal effects on soil microbial communities were small. Similarly, changing plot size from 300 m2 to 150 m2 in area caused small differences in the estimates of microbial community structure. In conclusion, microbial community structure and biochemical properties of soil from the tallgrass prairie were strongly impacted by cultivation, and the microbial community was not fully restored even after 30 years.  相似文献   

17.
Response of soil microbial communities to compost amendments   总被引：1，自引：0，他引：1  
Soil organic matter is considered as a major component of soil quality because it contributes directly or indirectly to many physical, chemical and biological properties. Thus, soil amendment with composts is an agricultural practice commonly used to improve soil quality and also to manage organic wastes. We evaluated in laboratory scale experiments the response of the soilborne microflora to the newly created soil environments resulting from the addition of three different composts in two different agricultural soils under controlled conditions. At a global level, total microbial densities were determined by classical plate count methods and global microbial activities were assessed by measuring basal respiration and substrate induced respiration (SIR). Soil suppressiveness to Rhizoctonia solani diseases was measured through bioassays performed in greenhouses. At a community level, the modifications of the metabolic and molecular structures of bacterial and fungal communities were assessed. Bacterial community level physiological profiles (CLPP) were determined using Biolog™ GN microtiter plates. Bacterial and fungal community structures were investigated using terminal restriction fragment length polymorphism (T-RFLP) fingerprinting. Data sets were analyzed using analysis of variance and ordination methods of multivariate data. The impact of organic amendments on soil characteristics differed with the nature of the composts and the soil types. French and English spent mushroom composts altered all the biological parameters evaluated in the clayey soil and/or in the sandy silty clay soil, while green waste compost did not modify either bacterial and fungal densities, SIR values nor soil suppressiveness in any of the soils. The changes in bacterial T-RFLP fingerprints caused by compost amendments were not related to the changes in CLPP, suggesting the functional redundancy of soil microorganisms. Assessing the density, the activity and the structure of the soil microflora allowed us not only to detect the impact of compost amendment on soil microorganisms, but also to evaluate its effect at a functional level through the variation of soil disease suppressiveness. Differences in disease suppressiveness were related to differences in chemical composition, in availability of nutrients at short term and in microbial composition due to both incorporation and stimulation of microorganisms by the compost amendments.  相似文献   

18.
Rates of degradation of pesticides by soil microorganisms are believed to depend on both microbial community composition and underlying soil physicochemical characteristics. The aim of this study was to determine which of these factors was more important in determining the rate of degradation of the fungicide metalaxyl-M in two soils. Soils exhibiting highly contrasting metalaxyl-M degradation rates were sterilised by gamma-irradiation and inoculated with either non-sterilised soil from the same site or with the soil from the contrasting site. After re-establishment of microbial communities, soils were treated with metalaxyl-M and the degradation rate (measured by 14C-HPLC), pH and microbial community structure (multiplex terminal-restriction fragment length polymorphism (T-RFLP) analysis of small subunit rRNA gene sequences) were assessed. Community composition was altered by the sterilisation and re-inoculation strategy but degradation in re-inoculated soils was still most rapid in the soil with the original faster degradation rate. This was the case regardless of the source of the soil inoculum, and the rate of degradation in the soil exhibiting the low natural degradation rate remained low when inoculated with the faster-degrading soil. The results suggest that while the slower-degrading soil possessed a degradative capacity, the degradation rate in this soil was significantly reduced by some of its physicochemical characteristics, despite introduction of the microbial community of the faster-degrading soil. These results and this experimental strategy provide a basis for the assessment of relative importance of the factors limiting biodegradation and management strategies required to enhance degradation rates.  相似文献   

19.
Colletia hystrix are dominant shrubs in the sclerophyllous matorral, a natural ecosystem in the central valley of Chile affected by erosion, soil with low fertility and limiting nitrogen. The soil microbial communities associated to these pioneer plants have received little attention even though they may have an important role in the ability of these to colonize the nutrient-poor soils from these semi-arid ecosystems. T-RFLP profiles using 16S rDNA were used to compare the bacterial community structure from soil samples (enriched and unenriched) associated to C. hystrix and neighboring soil without plant cover (bulk soil). Additionally, the microbial communities from both habitats were compared at the metabolic profile level using the Biolog EcoPlate™ system. Our results showed that the bacterial community from samples of soil associated to these plants formed a separate cluster from samples derived from the neighboring soil. These data suggest that soil associated to C. hystrix is a different microhabitat to bulk soil. When an enrichment step was performed on the samples, the T-RFLP profiles obtained showed few T-RFs suggesting that only some species were recovered. The enriched samples exhibited a low similarity between them and are clearly separated from the unenriched samples. On the other hand, the comparison of the unenriched samples from both habitats based on sole-carbon-source utilization profiles was unable to differentiate the samples according to their habitat.  相似文献   

20.
The increasing frequency and severity of wildfires has led to growing attention to the effects of fire disturbance on soil microbial communities and biogeochemical cycling. While many studies have examined fire impacts on plant communities, and a growing body of research is detailing the effects of fire on soil microbial communities, little attention has been paid to the interaction between plant recolonization and shifts in soil properties and microbial community structure and function. In this study, we examined the effect of a common post-fire colonizer plant species, Corydalis aurea, on soil chemistry, microbial biomass, soil enzyme activity and bacterial community structure one year after a major forest wildfire in Colorado, USA, in severely burned and lightly burned soils. Consistent with past research, we find significant differences in soil edaphic and biotic properties between severe and light burn soils. Further, our work suggests an important interaction between fire severity and plant effects by demonstrating that the recolonization of soils by C. aurea plants only has a significant effect on soil bacterial communities and biogeochemistry in severely burned soils, resulting in increases in percent nitrogen, extractable organic carbon, microbial biomass, β-glucosidase enzyme activity and shifts in bacterial community diversity. This work propounds the important role of plant colonization in succession by demonstrating a clear connection between plant colonization and bacterial community structure as well as the cycling of carbon in a post-fire landscape. This study conveys how the strength of plant–microbe interactions in secondary succession may shift based on an abiotic context, where plant effects are accentuated in harsher abiotic conditions of severe burn soils, with implications for bacterial community structure and enzyme activity.  相似文献   

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