煤矿复垦区不同恢复年限沙棘人工林土壤真菌群落特征

  目的  探讨矿区不同恢复年限复垦地沙棘人工林土壤真菌群落组成、多样性及其影响因子。  方法  以鄂尔多斯聚鑫龙煤矿复垦区不同恢复年限沙棘人工林为研究对象,撂荒草地为对照,对研究区土样进行采集,通过高通量测序对土样真菌群落测序分析。  结果  研究区共获得真菌8门、30纲、69目、164科和285属,其中子囊菌门和担子菌门为主要菌群,占样地所有菌门的98.2%,不同恢复年限不同土层真菌群落组成存在差异。随着恢复年限的增加,研究区土壤真菌门分类水平上主要类群的个体数及类群数整体呈现增长趋势,整体高于对照样地草地。另外,恢复7年的样地土壤真菌群落丰富度及多样性显著高于其他年限和撂荒草地。冗余分析表明,研究区不同恢复年限沙棘林土壤微生物群落组成主要由土壤pH、土壤有机质含量决定,同时也与土壤氮、磷、钾元素有关。  结论  不同恢复年限沙棘人工林土壤理化性质存在差异,恢复年限的增加提高了真菌的物种丰富度及多样性。     

不同地点和复垦方式煤矸石山土壤中丛枝菌根真菌群落变化

以山西省大同市晋华宫人工复垦和自然恢复煤矸石山以及忻州窑自然恢复煤矸石山为研究对象,采用IlluminaMiSeq高通量测序技术对三座煤矸石山土壤AM真菌群落组成进行分析,并测定其土壤理化性质,以探究不同地点煤矸石山不同复垦方式下土壤中丛枝菌根真菌（Arbuscular mycorrhizal fungi, AM真菌）群落组成的差异及其土壤影响因子。结果表明：晋华宫人工复垦煤矸石山和忻州窑自然恢复煤矸石山AM真菌多样性指数（Chao指数和香农-威纳指数）存在显著差异,但晋华宫人工复垦和自然恢复煤矸石山AM真菌群落的多样性指数差异不显著。试验共检测到67个AM真菌OTUs,可鉴定到3个AM真菌属级分类单元,其中球囊霉属（Glomus）在晋华宫人工复垦煤矸石山、晋华宫自然恢复煤矸石山和忻州窑自然恢复煤矸石山中均为最优势菌,多样孢囊霉属（Diversispora）、类球囊霉属（Paraglomus）仅出现在晋华宫自然恢复煤矸石山。多元置换方差分析和多维尺度分析结果表明,晋华宫两种恢复方式的煤矸石山之间AM真菌群落组成差异不显著,而晋华宫与忻州窑两个地点的煤矸石山AM真菌群落组成差异显著。AM...     

Fungal diversity in set-aide agricultural soil investigated using terminal-restriction fragment length polymorphism

As part of the restoration of biodiversity on former agricultural land there has been focused on methods to enhance the rate of transition from agricultural land towards natural grasslands or forest ecosystems. Management practices such as sowing seed mixtures and inoculating soil of later successional stages have been used. The aim of this study was to determine the effects of a managed plant community on the diversity of soil fungi in a newly abandoned agricultural land. A field site was set up consisting of 20 plots where the plant diversity was managed by either sowing 15 plant species, or natural colonization was allowed to occur. The plant mixture contained five species each of grasses, legumes and forbs that all were expected to occur at the site. A subset of the plots (five from each treatment) was inoculated with soil cores from a late successional stage. The plant community composition was subject to a principal component analysis based on the coverage of each species. Five years after abandonment, soil samples were taken from the plots, DNA was extracted and the ITS region of the rDNA gene was amplified using fluorescently labelled fungal specific primers (ITS 1F/ITS 4). The PCR products were digested using HinfI and TaqI and sequenced. Results from both restriction enzymes were combined and a principal component analysis performed on the presence/absence of fragments. Also the fungal diversity expressed as number of restriction fragments were analysed. There was significantly higher fungal species richness in the experimental plots compared to the forest and field soils, but no differences between sown and naturally colonized plots. The different plant treatments did not influence the below ground fungal community composition. Soil water content on the other hand had an impact on the fungal community composition.     

Constraints on development of fungal biomass and decomposition processes during restoration of arable sandy soils

In an earlier study we reported the apparent stabilization of a low fungal biomass in ex-arable lands during the first decades after abandonment. It was hypothesized that the lack of increase in fungal biomass was due to constraints on development of fungi with persistent hyphae such as lignocellulolytic basidiomycetes and ericoid mycorrhizal fungi. With respect to the former group, the slow increase of the pool of lignocellulose-rich organic matter was expected to be the major constraint for their development. To study this, we enriched soil samples of one arable land, of two recently abandoned arable lands, of one older abandoned arable land and of heathland with carbon substrates that differed in composition (glucose, cellulose and sawdust). In addition, we combined the effect of carbon addition on fungal biomass development in arable and recently abandoned lands with inoculation of 1% of soil from the older abandoned site and the heathland. All treatments induced a fast increase and a subsequent rapid decline in fungal biomass in the arable and ex-arable fields. Denaturing Gradient Gel Electrophoresis (DGGE) band patterns and enzyme activities did show differences between the carbon treatments but not between the recent and older abandoned field sites, indicating a similarly responding fungal community even after three decades of land abandonment and irrespective of soil inoculation. Identification of fungi by sequencing and culturing confirmed that decomposition processes were mostly dominated by opportunistic fungi in arable and ex-arable fields. In the heathland, only a very slow increase of microbial activity was observed after addition of carbon and sequencing of DGGE bands showed that ericoid mycorrhiza (ERM) fungi were responsible for carbon decomposition. We conclude that an increase of enduringly present fungal hyphae in ex-arable land may only be possible when a separate litter layer develops and/or when suitable host plants for ERM fungi become established.     

福建省福州市叶蜡石矿区废弃地土壤肥力状况分析

福州市叶蜡石矿的保有储量居全国首位,矿山开发使得矿区地质环境遭受破坏,地被几乎丧失殆尽。对福州市晋安区宦溪镇峨嵋叶蜡石矿区进行土壤和植被调查、试验分析,结果表明：矿区废弃地土壤酸性较强,土壤碱解氮、速效磷、速效钾、有机质含量都较自然植被下土壤有非常明显地降低,矿区废弃地有一定的自然恢复能力,但相当缓慢,后期需要采取人工干预措施。     

Grassland management influences spatial patterns of soil microbial communities

Soil micro-organisms play a vital role in grassland ecosystem functioning but little is known about the effects of grassland management on spatial patterns of soil microbial communities. We compared plant species composition with terminal restriction fragment length polymorphism (T-RFLP) fingerprints of soil bacterial and fungal communities in unimproved, restored and improved wet grasslands. We assessed community composition of soil micro-organisms at distances ranging from 0.01 m to 100 m and determined taxa–area relationships from field- to landscape level. We show that land management type influenced bacterial but not fungal community composition. However, extensive grassland management to restore aboveground diversity affected spatial patterns of soil fungi. We found distinct distance–decay and small-scale aggregation of fungal populations in extensively managed grasslands restored from former arable use. There were no clear spatial patterns in bacterial communities at the field-scale. However, at the landscape level there was a moderate increase in bacterial taxa and a strong increase in fungal taxa with the number of sites sampled. Our results suggest that grassland management affects soil microbial communities at multiple scales; the observed small-scale variation may facilitate plant species coexistence and should be taken into account in field studies of soil microbial communities.     

降水变化和氮沉降对荒漠草原土壤丛枝菌根真菌群落结构的影响

降水变化和氮沉降是影响植物、微生物和土壤环境变化的两个重要方面。尽管丛枝菌根（AM）真菌在陆地生态系统中起着至关重要的作用，但人们对降水变化和氮添加如何交互影响AM真菌群落仍知之甚少。本研究以短花针茅荒漠草原为研究对象，采用裂区设计，主区为自然降雨(CK)、增雨30%(W)和减雨30%(R)三个水分梯度，副区为0(N0)，30(N30)，50(N50)和100(N100) kg?hm-2?a-1 四个氮素梯度共12个处理，通过高通量测序分析了土壤中AM真菌群落的多样性和组成。结果发现，水分处理对土壤AM真菌的Alpha多样性有促进作用，氮素处理抑制了土壤AM真菌的Alpha多样性，水分增加和氮素添加的交互作用促进了AM真菌的Alpha多样性增加，并改变了土壤AM真菌群落组成。水分和氮素刺激了各功能型植物生物量的增加，氮添加使多年生杂草和半灌木、小半灌木生物量显著增加，多年生禾草生物量显著减少。此外，多型孢子菌科的相对丰度与一二年生植物和半灌木、小半灌木生物量呈显著正相关，一二年生植物和半灌木、小半灌木生物量在氮添加和增雨处理下增加。本研究证明了AM真菌群落在短期气候变化下的稳定性。此外，AM真菌在科水平上的丰度与各生活型植物地上生物量的相关性证明了地上和地下生态系统的连通性。     

钼矿开采对球囊霉素相关土壤蛋白和土壤化学计量特性的影响

以不同开采程度钼矿区根际土壤为研究对象，探索了钼矿开采对土壤球囊霉素相关土壤蛋白、化学计量特性及其两者之间关系的影响。结果表明，开采区土壤碳、氮含量分别为25.30和1.00 g/kg，显著低于恢复区和未开采区土壤的碳、氮含量。开采区土壤的碳氮比达到29.36，分别是恢复区和未开采区的2.02倍和1.30倍。恢复区和未开采区土壤的总提取球囊霉素含量为2.81和3.64 mg/g，易提取球囊霉素含量为1.22和2.02 mg/g，分别是开采区土壤总提取和易提取球囊霉素的2.08倍、2.70倍和1.97倍、3.26倍。此外，土壤碳、氮含量对丛枝菌根真菌分泌球囊霉素相关土壤蛋白有显著的影响。可见，钼矿开采主要导致了土壤碳、氮的大量流失，并对丛枝菌根真菌分泌球囊霉素相关土壤蛋白具有明显的抑制作用。     

The seasonal pattern of soil microbial community structure in mesic low arctic tundra

Soil microorganisms are critical to carbon and nutrient fluxes in terrestrial ecosystems. Understanding the annual pattern of soil microbial community structure and how it corresponds to soil nutrient availability and plant production is a fundamental first step towards being able to predict impacts of environmental change on ecosystem functioning. We investigated the composition, structure and nutrient stoichiometry of the soil microbial community in mesic arctic tundra on 9 sample dates in 6 months from winter to fall using phospholipid fatty acid analysis (PLFA), quantitative polymerase chain reaction (qPCR), epifluorescent microscopy and chloroform-fumigation–extraction (CFE). PLFA analysis indicates that the winter microbial community was fungal-dominated, cold-adapted and associated with high C, N and P in the soil solution and microbial biomass. The microscopy data suggest that both bacteria and fungi were active and growing in soils between −5 °C and 0 °C. A significant shift occurred in the PLFA data, qPCR patterns, microscopy and microbial biogeochemistry after the thaw period, resulting in a distinct community that persisted through our spring, summer and fall sample dates, despite large changes in plant productivity. This shift was characterised by increasing relative abundances of certain bacteria (especially Gram +ves) as well as a decline in fungal biomass, and corresponded with decreasing C, N and P in the soil solution. The summer period of low substrate availability (plant–microbe competition) was associated with microbial indicators of nutritional stress. Overall, our results indicate that tundra microbial communities are clearly differentiated according to the changes in soil nutrient status and environmental conditions that occur between winter and post-thaw, and that those changes reflect functionally important adaptations to those conditions.     

Fungal but not bacterial soil communities recover after termination of decadal nitrogen additions to boreal forest

The rate at which formerly nitrogen loaded forests will return to their natural nitrogen-limited state is of considerable scientific and societal interest. Yet the sensitivity of soil microorganisms to these putative changes is mainly unknown. We report effects on fungal and bacterial communities caused by two decades of chronic nitrogen fertilization and subsequent changes 14 years after termination of nitrogen load. We compare these changes in community composition with those observed in natural nitrogen supply and pH gradients using DNA fingerprinting methods and Sanger sequencing.Soil fungal ITS length-heterogeneity profiles correlated equally well to carbon-to-nitrogen ratios and pH. Sequencing results indicated a clear decrease in the relative abundance of amplicons ascribed to known ectomycorrhizal fungi in both natural and experimental high nitrogen conditions, and a recovery of species in the terminated nitrogen treatment. The dominant sequences in low nitrogen soils were identified as members of Piloderma spp. Terminal restriction fragment length profiles of the bacterial 16S rRNA gene were linked to carbon-to-nitrogen ratios and pH in the natural locations but to soil nitrogen in the nitrogen addition experiment that had low variability in pH. Sequencing revealed the dominance of Acidobacteria and Proteobacteria in all soils but also showed a marked increase in Bacteroidetes in high nitrogen treatment not evident in the natural high nitrogen and high pH environments. Proteobacteria sequences included described strains from high-organic and low-pH systems that are believed be involved in degradation of complex plant material.There were signs of recovery of fungal but not of bacterial communities in the sense that community's in terminated nitrogen addition plots did not differ significantly from those in control plots or from the low nitrogen stands in the natural nitrogen supply gradient. The need of further examination of the seemingly functionally redundant bacterial communities is stressed.     

Fungal biomass development in a chronosequence of land abandonment

Based on biomass size, the contribution of fungi to nutrient cycling and soil properties is in general more important in natural ecosystems than in agro-ecosystems. Therefore, we expect an increase of fungal biomass after cessation of cultivation to values of a natural ecosystem. However, so far, information on fungal dynamics in ex-arable land is limited. We quantified fungal biomass in a chronosequence of 26 ex-arable fields in the Netherlands ranging from 1-34 years of abandonment. Agricultural lands and semi-natural heathlands were included as reference sites for initial and final stages of succession, respectively. Fungal biomass values were low at the start of land abandonment and increased during the first 2 years after abandonment. After this initial increase of fungal biomass no further increase was apparent, neither did we find any relations with time since abandonment and changes in soil acidity, organic matter content or organic matter quality (quantity of recalcitrant C and C:N ratio). Therefore, we conclude that the initial increase of fungal biomass is caused by stopping agricultural management activities. A phase of stabilization occurs for at least three decades in which the size of the fungal biomass did not change significantly. We observed much higher values for fungal biomass, total and recalcitrant carbon in the heathland sites. We propose that a change in abiotic soil properties is a prerequisite for further increase of fungal biomass towards levels of representative heathlands.     

Phylogenetic structure of arbuscular mycorrhizal community shifts in response to increasing soil fertility

Understanding the underlying mechanisms driving responses of belowground communities to increasing soil fertility will facilitate predictions of ecosystem responses to anthropogenic eutrophication of terrestrial systems. We studied the impact of fertilization of an alpine meadow on arbuscular mycorrhizal (AM) fungi, a group of root-associated microorganisms that are important in maintaining sustainable ecosystems. Species and phylogenetic composition of AM fungal communities in soils were compared across a soil fertility gradient generated by 8 years of combined nitrogen and phosphorus fertilization. Phylogenetic patterns were used to infer the ecological processes structuring the fungal communities. We identified 37 AM fungal virtual taxa, mostly in the genus Glomus. High fertilizer treatments caused a dramatic loss of Glomus species, but a significant increase in genus richness and a shift towards dominance of the lineage of Diversispora. AM fungal communities were phylogenetically clustered in unfertilized soil, random in the low fertilizer treatment and over-dispersed in the high fertilizer treatments, suggesting that the primary ecological process structuring communities shifted from environmental filtering (selection by host plants and fungal niches) to a stochastic process and finally to competitive exclusion across the fertilization gradient. Our findings elucidate the community shifts associated with increased soil fertility, and suggest that high fertilizer inputs may change the dominant ecological processes responsible for the assembly of AM fungal communities towards increased competition as photosynthate from host plants becomes an increasingly limited resource.     

Fungal biomass production and turnover in soil estimated using the acetate-in-ergosterol technique

We report the first attempt to estimate fungal biomass production in soil by correlating relative fungal growth rates (i.e., acetate incorporation into ergosterol) with fungal biomass increase (i.e., ergosterol) following amendments with dried alfalfa or barley straw in soil. The conversion factor obtained was then used in unamended soil, resulting in fungal biomass productions of 10-12 μg C g⁻¹ soil, yielding fungal turnover times between 130 and 150 days. Using a conversion factor from alfalfa-treated soil only resulted in two times higher estimates for biomass production and consequently lower turnover times. Comparing fungal biomass production with basal respiration indicated that these calculations overestimated the former. Still, the turnover times of fungal biomass in soil were in the same range as turnover times estimated in aquatic systems. The slow turnover of fungal biomass contrasts with the short turnover times found for bacteria. The study thus presents empirical data substantiating the theoretical division of bacteria and fungi into a fast and a slow energy channel, respectively, in the soil food web.     

干旱半干旱煤矿区联合接菌对土壤改良动态生态效应

针对干旱半干旱地区煤炭开采造成的生态破坏问题,利用微生物-植物-土壤的综合作用效应,可加快矿区受损生态的修复进程。为评价不同接种微生物在矿区生态修复过程中的动态作用效果,以神东矿区大柳塔采煤塌陷区的紫穗槐(Amorpha fruticosa L.)为研究对象,通过原位监测,研究接种不同菌根真菌、解磷细菌或同时接种不同微生物处理对不同复垦年限下紫穗槐植株生长(株高和冠幅)、菌根效应(菌根侵染率和菌丝密度)、土壤养分及性质和复垦4 a不同生长季叶片养分和抗逆性的影响规律,以确定接种不同微生物菌剂对紫穗槐生长的影响和对土壤的改良效果。结果表明,与不接种相比,接种摩西管柄囊霉(Funneliformis mosseae)、根内球囊霉(Rhizophagus intraradices)及解磷细菌(Bacillus megaterium)均能显著增加紫穗槐的株高和冠幅(P0.05),提高其生长旺盛期叶片的氮、磷和钾浓度,提高叶片氮钾的再吸收,降低叶片相对含水率,提高7-9月份叶片脯氨酸、可溶性糖的积累,显著降低土壤pH值(P0.05),提高土壤易提取球囊霉素、总提取球囊霉素、碱解氮、速效磷和速效钾等指标的含量。不同接种处理对紫穗槐生长、菌根侵染率、叶片抗逆性、土壤氮磷钾养分、易提取球囊霉素和总提取球囊霉素含量的影响随着复垦时间的延长具有显著的协同作用。摩西管柄囊霉与解磷细菌同时接种在复垦4 a后仍能促进紫穗槐菌根效应的发挥,促进植物生长,提高植物的养分和抗逆性,改良土壤,在干旱半干旱煤矿区生态修复进程中具有积极作用。     

Direct and indirect effects of enhanced UV-B radiation on the decomposing and competitive abilities of saprobic fungi

Increases in UV-B radiation have been shown to slow the rate of litter decomposition in ecosystems. However, it is unclear if this is a result of direct UV-B effects on saprobic microorganisms, or a result of UV-B-induced changes in litter quality that indirectly affect decay by saprobes. In this study, we evaluated the magnitude of direct and indirect effects on litter decomposition of Brassica napus by soil fungi, under growth chamber conditions. We found that, both, direct and indirect UV-B negatively influenced litter decomposition, however, direct effects were much more pronounced. We then tested whether UV-B radiation would have species-specific effects on fungal colonization and competitive ability, rather than influencing all fungal species equally. We predicted that darkly pigmented fungi would increase their relative competitive ability under high UV-B. The test fungi were all isolated from field soil under Brassica napus. Two fungi were hyaline (Aspergillus terreus, Trichoderma koningii), two were darkly-pigmented (Cladosporium sphaerospermum, Epicoccum purpurascens) and one had a hyaline mycelium but darkly-pigmented conidia (Aspergillus niger). Elevated UV-B radiation had differential direct and indirect effects on fungal growth, and caused shifts in the competitive balances between pigmented and non-pigmented fungi. However, in only two of six pair-wise challenges did the pigmented species increase their relative competitive ability under UV-B conditions. It is clear that UV-B profoundly influence fungal community structure in soil, but the direction of such effects remains unpredictable.     

Successional trajectories of soil nematode and plant communities in a chronosequence of ex-arable lands

Conversion of arable land into semi-natural grassland or heath land is a common practice for restoring and conserving plant diversity. However, little is known about the effectiveness of land conversion for restoring and conserving taxonomic and functional diversity in the soil. We studied soil nematode community development in a chronosequence of abandoned fields and related this to plant community development. The taxonomic and functional composition of the soil nematode community was analyzed to detect changes in soil food web structure, using semi-natural sites and theoretical plant and soil communities as references.While plant communities clearly developed towards the semi-natural references, there was less direction in succession of nematode taxa. The number of fungal feeding nematodes increased after land abandonment. Numbers of omni-carnivorous nematodes expanded only during the first years, after which there were no substantial changes for the next three decades. Plant communities on the ex-arable fields developed towards the theoretical reference plant associations Galio hercynici-Festucetum ovinae and Genisto anglicae-Callunetum. Nematode communities developed away from a theoretical community indicative of arable land, but there was no clear development towards a theoretical (semi-)natural reference. Our results show that restoration and conservation of plant communities is of limited indicative value for developments belowground: successful restoration of plant diversity does not necessarily imply successful restoration of belowground diversity. Assessing the impact of conservation measures on restoring soil biodiversity requires information on belowground community composition of (semi-)natural areas in order to establish proper references for restoration sites.     

Influence of long-term fertilisation and crop rotation on changes in fungal and bacterial residues in a tropical rice-field soil

Amino sugars, as a microbial residue biomarker, are highly involved in microbial-mediated soil organic matter formation. However, accumulation of microbial biomass and responses of bacterial and fungal residues to the management practices are different and poorly characterized in rice soils. The objectives of this study were to evaluate the effects of mineral fertiliser (MIN), farmyard manure (FYM) and groundnut oil cake (GOC) on crop yield and co-accumulation of microbial residues and microbial biomass under rice-monoculture (RRR) and rice–legume–rice (RLR) systems. In the organic fertiliser treatments and RLR, rice grain yield and stocks of soil and microbial nutrients were significantly higher than those of the MIN treatment and RRR, respectively. The increased presence of saprotrophic fungi in the organic fertiliser treatments and RRR was indicated by significantly increased ergosterol/C_mic ratio and extractable sulphur. In both crop rotation systems, the long-term application of FYM and GOC led to increased bacterial residues as indicated by greater accumulation of muramic acid. In contrast, the higher fungal C/bacterial C ratio and lower ergosterol/C_mic ratio in the MIN treatment, is likely caused by a shift within the fungal community structure towards ergosterol-free arbuscular mycorrhizal fungi (AMF). The organic fertiliser treatments contributed 22 % more microbial residual C to soil organic C compared to the MIN treatment. Our results suggest that the negative relationship between the ratios ergosterol/C_mic and fungal C/bacterial C encourages studying responses of both saprotrophic fungi and AMF when assessing management effects on the soil microbial community.     

Soil community changes during secondary succession to naturalized grasslands

Succession to a naturalized grassland from former agricultural land and pastures is accompanied by changes in plant biodiversity and in the soil community. These changes are the result of a reduction or elimination of management, fertilizer applications and of grazing by large herbivores. We review soil biology studies on agricultural land that are in various successional stages towards naturalized grasslands, where interactions between plant species composition changes and the soil ecology affect each other. In many chronosequence studies, the soil microbial community tends to shift towards a less bacterial, and more fungal dominated food web energy channel following a reduction in fertilizer inputs and grazing intensity. Whereas changes in microarthropod communities are obscured, nematode trophic functional group (ecological guild) changes respond to both plant and soil community changes. There are opportunities to further study the feedback interactions between roots and soil organisms in grasslands. A better understanding of the molecular feedback mechanisms would be beneficial in long-term grassland management.     

Soil fungal and prokaryotic community structure exhibits differential short-term responses to timber harvest in the Pacific Northwest

Conventional clear-cut timber harvest is a widespread industrial practice across the Pacific Northwest;however,information regarding how these practices impact soil microbial community structure at the regional scale is limited.With evidence of consistent and substantial impact of harvest on soil microbial functional profiles across the region(despite a range of environmental conditions),the objective of this study was to determine the extent to which harvest also influences the structure of prokaryotic and fungal soil microbial communities,and how generalized these trends are throughout the geographic region.Paired soil samples were collected one year before and after harvest across nine second-growth Douglas-fir forests in the Pacific Northwest.Total community DNA was extracted from the soils,and high-throughput targeted gene sequencing of the 16 S r RNA gene for prokaryotes and the internal transcribed spacer(ITS)gene for fungi was performed.Alpha diversity was consistently and significantly higher after harvest;it was moderately so for fungal communities(+14.6%),but only marginally so for prokaryotic communities(+2.0%).Similarly,on average,a greater proportion of the variation in the community structure of fungi(20.1%)at each site was associated with forest harvest compared to that of prokaryotes(13.2%).Overall,the greatest influence of timber harvest on soil microbial communities appeared to be a relative depletion of ectomycorrhizal fungi,with a concomitant enrichment of saprotrophic fungi.Understanding the short-term responses of soil microbial communities across the region,particularly those of tree root-associated symbionts,may aid our understanding of the role soil microbial communities play in ecological succession.