Impact of Vegetation Restoration on Soil Fungal Community Structure in Karst Rocky Desertification Areas

In this paper,managed forest(MF)and natural forest(NF)in the Huajiang Demonstration Zone of Guanling,Guizhou were selected as research objects,and cropland(CL)was taken as control.High-throughput sequencing technology was used to study the characteristics of fungal community composition and species diversity in the surface(0-10 cm)soil of each restoration measure,in order to reveal the dominant soil fungal groups and fungal community composition in karst rocky desertification areas,which was conducive to a more comprehensive understanding of the soil conditions of different vegetation restoration measures.Research has shown that vegetation restoration significantly affected the diversity of soil fungal community,with significant increases in Sob index,Ace index,and Chao index.The vegetation restoration has significantly changed the composition of fungal community.The dominant fungi in the CL topsoil are Sordariomycetes(62.28%),Dothideomycetes(12.34%),and Eurotiomycetes(9.12%);the dominant fungi in the MF soil are Sordariomycetes(45.05%),Dothideomycetes(14.74%),and Mortierellomycetes(10.40%);the dominant fungi in the NF soil are unclassified fungal community(26.38%),Sordariomycetes(19.78%),and Agaricomycetes(13.82%).Vegetation restoration has changed the key fungal groups in the soil.Sordariomycetes,Fusarium,and Setophoma are the key dominant fungal groups in CL soil;Dioszegia is key dominant fungal group in MF soil;c_unclassified_k_Fungi,p_unclassified_k_Fungi,o_unclassified_k_Fungi,f_unclassified_k_Fungi,g_unclassified_k_Fungi,Teichospora,and Diaporthe are key dominant fungal groups in NF soil.

Soil Fungal Diversity and Community Composition in Response to Continuous Sweet Potato Cropping Practices

Soil fungi are extremely important for maintaining soil health and plant production in agricultural systems.Currently,the effect of continuous cropping of sweet potato on soil fungal communities and physiochemical parameters has not been well documented.In the present study,four sweet potato fields consecutively monocultured for 1,2,3,and 4 years were selected to investigate the effect of monoculture on soil fungal communities through Illumina MiSeq sequencing.Continuous cropping of sweet potatoes dramatically altered the fungal community composition,whereas fungal diversity was almost unchanged.Ascomycota and Basidiomycota were the most abundant phyla in all soil samples,accounting for 32.59%and 21.14%of the average relative abundance,respectively.The abundance of some potential pathogens,such as Ascobolus spp,specifically Ascobolus stercorarius,and some unknown fungi increased significantly as the sweet potato monoculture period increased,and their presence were highly positively correlated with disease incidence.In contrast,Basidiomycota,Bullera,Fusarium and Trichocladium most likely play roles as antagonists of sweet potato disease development,as their relative abundance decreased significantly over time and were negatively correlated with disease incidence.Redundancy and correlation analyses revealed that soil pH and organic carbon content were the most important factors driving these changes.Our findings provided a dynamic overview of the fungal community and presented a clear scope for screening beneficial fungi and pathogens of sweet potato.

Rhizosphere Soil Fungal Diversity and Soil Physicochemical Properties of Different Vegetations in Tundra of Changbai Mountain

By studying the diversity and community structure of rhizosphere soil fungi of different plants in the tundra on the northern slope of Changbai Mountain, it provides theoretical support for the restoration of environmental degradation and in-depth study of fungal diversity in the tundra of Changbai Mountain. High-throughput sequencing technology was used to determine the ITS1 region of fungal amplicons, so as to analyze the diversity of fungal communities in the rhizosphere soil of six plants in the tundra of Changbai Mountain, and to analyze the correlation between the environment and the diversity and richness of fungal communities in combination with relevant soil physical and chemical factors. The diversity and richness of fungal community in the rhizosphere soil of six plants in Changbai Mountain tundra were different. The Simpson and Shannon indexes of Saxifraga stolonifera Curt were the highest, and the richness of fungal community in Dryas octopetala was the highest. The analysis of fungal community composition showed that the fungal colonies in plant rhizosphere soil samples mainly belonged to Ascomycota and Basidiomycota, which were the main dominant phyla. Mortierella, Fusarium and Sordariomycetes are common fungal genera in the rhizosphere soil of six plants, but their abundances are different among different plants. Water content was negatively correlated with fungal diversity, and TP was positively correlated with fungal community diversity. There were some differences in the composition and diversity of rhizosphere soil fungal communities of six plants in Changbai Mountain tundra. Ascomycota and Basidiomycota were the main soil fungal phyla in the rhizosphere of six plants in Changbai Mountain tundra. The results could provide theoretical guidance for ecological protection of Changbai Mountain tundra.

Plant diversity is coupled with soil fungal diversity in a natural temperate steppe of northeastern China

Soil fungi and aboveground plant play vital functions in terrestrial ecosystems,while the relationship between aboveground plant diversity and the unseen soil fungal diversity remains unclear.We established 6 sites from the west to the east of the temperate steppe that vary in plant diversity(plant species richness:7-32)to explore the relationship between soil fungal diversity and aboveground plant diversity.Soil fungal community was characterized by applying 18S rRNA gene sequencing using MiSeq PE300 and aligned with Silva 132 database.As a result,soil fungal community was predominately composed of species within the Ascomycota(84.36%),Basidiomycota(7.22%)and Mucoromycota(6.44%).Plant species richness occupied the largest explanatory power in structuring soil fungal community(19.05%–19.78%).The alpha(α)diversity of the whole soil fungi and Ascomycota showed a hump-backed pattern with increasing plant species richness,and the beta(β)diversity of the whole soil fungi and Ascomycota increased with increasing plantβdiversity.Those results indicated that soil fungi and external resources were well balanced at the 20-species level of plant and the sites were more distinct in the composition of their plant communities also harbored more distinct soil fungal communities.Thus,plant diversity could predict both soil fungalαandβdiversity in the temperate steppe of northeastern China.

Contrasting soil fungal communities in Mediterranean pine forests subjected to different wildfire frequencies

Mediterranean forest ecosystems are characterized by various vascular plant groups with their associated mycor-rhizae and free living soil fungi with various ecological functions.Fire plays a major role in Mediterranean ecosystem dynamics and impacts both above-and below-ground community structure and functioning.However,studies on the effects induced by altered disturbance regimes(associated with recent land use and climate extremes)on fire ecology and especially on its below-ground impacts are few.The objectives of this study were to evaluate the effects of different wildfire regimes on soil fungal community structure using two different molecular methods.We investigated the long-term effects of wildfire on soil fungal communities associated with Pinus pinaster forests in central Portugal,by comparing the results of denaturing gradient gel electrophoresis(DGGE)-based profiling with those obtained with 454 pyrosequencing.Four forest stands with differing fire history and fire return interval,and vegetation cover(mature forest,early successional stage of pine regeneration,and forest converted to scrubland)were sampled 6 years after the last fire event.The pyrosequencing-based approach indicated ca.eight-fold higher numbers of taxa than DGGE.However,fungal community fingerprinting data obtained for the different study stands with DGGE were congruent with those obtained with pyrosequencing.Both short(7.6 years)and long(24 years)fire return intervals(indicated by the presence of ericaceous shrubs in the understorey)induced a decrease in the abun-dance ratio between basidiomycetes and ascomycetes and appeared to reduce the frequency of ectomycorrhizal fungal species and saprophytes.Wildfire significantly reduced the frequency of late stage successional taxa(e.g.Atheliaceae and Cantharellales)and known or putative saprophytes belonging to the Clavulinaceae and the Archaeorhizomycetaceae.Conversely,early successional fungal species belonging to the Thelephoraceae were favoured by both fire return inter-vals,while the abundance of Cortinarius and Hebeloma,which include several Cistus-specific species,increased with short wildfire return intervals.This last finding highlights the relationship between postfire vegetation composition and cover(vegetation successional stage),and fungal symbionts.We hypothesise that these changes could,in the long term,exhaust the resilience of Mediterranean pine forest vegetation and associated soil fungal communities by preventing pine regeneration.

Changes in fungal community and diversity in strawberry rhizosphere soil after 12 years in the greenhouse

Soil fungi play a very important role in the soil ecological environment. In agricultural production, long-term monoculture and continuous cropping lead to changes in fungal community diversity. However, the effects of long-term monoculture and continuous cropping on strawberry plant health and fungal community diversity have not been elucidated. In this study, using high-throughput sequencing(HTS), we compared the fungal community and diversity of strawberry rhizosphere soil after various durations of continuous cropping(0, 2, 4, 6, 8, 10 and 12 years). The results showed that soil fungal diversity increased with consecutive cropping years. Specifically, the soil-borne disease pathogens Fusarium and Guehomyces were significantly increased after strawberry continuous cropping, and the abundance of nematicidal(Arthrobotrys) fungi decreased from the fourth year of continuous cropping. The results of correlation analysis suggest that these three genera might be key fungi that contribute to the changes in soil properties that occur during continuous cropping. In addition, physicochemical property analysis showed that the soil nutrient content began to decline after the fourth year of continuous cropping. Spearman's correlation analysis showed that soil pH, available potassium(AK) and ammonium nitrogen(NH_4^+-N) were the most important edaphic factors leading to contrasting beneficial and pathogenic associations across consecutive strawberry cropping systems.

Effects of Consecutively Monocultured Rehmannia glutinosa L.on Diversity of Fungal Community in Rhizospheric Soil

Continuous monoculture problems, or replanting diseases, are one of the key factors affecting productivity and quality of Chinese medicinal plants. The underlying mechanism is still being explored. Most of the studies on continuous monoculture ofRehmannia glutinosa L. are focused on plant nutritional physiology, root exudate, and its autotoxieity. However, the changes in the diversity of microflora in the rhizosphere mediated by the continuous monoculture pattern have been remained unknown. In this study, terminal restriction fragment length polymorphism （T-RFLP） technique was used for fingerprinting fungal diversity in the rhizosphere soil sampled from the fields ofR. glutinosa monocultured for 1 and 2 yr. The results showed that the structure of fungal community in consecutively moncultured rhizosphere soil was different from that in control soil （no cropping soil）, and varied with the consecutive monoeulture years （1 and 2 yr）. The comprehensive evaluation index （D） of fungal community estimated by principal component analysis of fragment number, peak area, Shannon-Weiner index, and Margalef index was higher in 1 yr monoculture soil than that in 2 yr monoculture soil, suggesting that consecutive monoculture of R. glutinosa could be a causative agent to decrease the diversity of fungal community in the rhizosphere soil.

Microfungal communities in soil polluted with fluoride

There have been identified three zones according to the degree of soil pollution with fluoride in the impact area of air emissions of the Kandalaksha Aluminium Smelter (Russia): zone of maximum pollution up to 2.5 km from the emission source with the content of fluoride from 5000 to 1200 mg/kg, zone of strong pollution up to 13 km from the plant with the content of fluoride between 1200-400 mg/kg and zone of moderate pollution up to 20 km from the source with content of fluoride between 400-200 mg/kg. Emissions of the aluminium plant have reduced the number and the diversity of fungi and have caused an increase in fungal communities that are potentially pathogenic fungi. The biomass of fungi has decreased in the organic horizon of the maximum polluted soil from 5.4 to 3.6 mg/g. As a whole, emissions from the aluminium plant in the Murmansk region are less toxic for the environment, than emissions of copper-nickel enterprises.

种植模式对当归根际土壤真菌群落与功能类群的影响

再植障碍问题限制了当归产业健康发展。为了建立高效种植方式,在甘肃渭源县设置5种种植方式[A:豌豆-小麦-当归;B:豌豆-蒙古黄芪-当归;C:豌豆-马铃薯-当归;D:豌豆-当归-当归(对照);E:豌豆-休耕-当归],采挖期通过Illumina Hisqe 2500高通量测序平台测定了不同种植模式下当归根际土壤真菌ITS1变异区的基因序列,分析不同种植方式对当归根际土壤真菌群落和功能差异性的影响。结果表明:(1)5种种植方式下当归根际真菌多样性差异不大,较对照D处理,A、B、C和E处理的Chao1指数、Ace指数和Shannon指数较低,Simpson指数较高。(2)5种种植方式下当归根际土壤真菌群落隶属于11门167属,其中,子囊菌门(Ascomycota)、被孢菌门(Mortierellomycota)、担子菌亚门(Basidiomycota)和壶菌门(Chytridiomycota)为优势门;被孢霉属(Mortierella)、四枝孢属(Tetracladium)为优势属。(3)冗余度分析发现:在门水平影响土壤真菌群落结构组成的主要因子为速效钾、电导率、pH值,在属水平影响土壤真菌群落结构组成的主要因子为有机质、pH值、二氧化碳呼吸速率。(4)FUNGuild预测表明:植物病原体和木质腐生真菌功能群的相对丰度较高。综上所述,不同作物轮作较当归连作,降低了当归根际土壤真菌群落的相对丰度和多样性,有利于根际土壤真菌群落向有益的方向发展。

复合木霉制剂防治黄连根腐病及其机理研究

为评价复合木霉制剂对黄连根腐病的防治效果,并揭示其防病机理,为黄连根腐病专用微生物农药的研发奠定基础,本试验将深绿木霉Trichoderma atroviride、长枝木霉T.longibrachiatum、钩状木霉T.hamatum、拟康宁木霉T.koningiopsis等4种木霉配制的复合制剂和尖镰孢Fusarium oxysporum以不同的方式分别施用于黄连,统计根腐病发生情况,检测黄连根部防御酶活性,用高通量测序分析根际土壤真菌群落结构。结果表明,复合木霉制剂对尖镰孢导致的根腐病具有明显预防效果;复合木霉制剂和尖镰孢分别接种黄连可提高SOD、POD、CAT、PAL、PPO等防御性酶活性,产生诱导抗性;而它们先后接种黄连可产生强化效应,从另一个途径提高植株抗病性。复合木霉制剂和尖镰孢都会降低真菌的数量、多样性,和某些真菌的相对丰度,而复合木霉制剂的抑菌作用更强烈,尤其能明显抑制尖镰孢、Ilyonectria sp.等病原真菌的生长,且能改善土壤真菌群落结构。木霉和尖镰孢都能在土壤中较长期定殖。可见,复合木霉制剂可以预防尖镰孢导致的黄连根腐病,防病机理包括诱导黄连植株产生抗性,接种后再遭受病原菌侵染产生的强化效应,优化土壤真菌群落结构,抑制土壤中病原菌等,且有效期较长。因此复合木霉制剂具有开发为微生物农药防治黄连根腐病的潜力。

基于高通量测序的昭通核心烟区植烟土壤真菌多样性分析

本研究利用高通量测序技术,从分子水平探究昭通8个种烟县(区)新烟区、土传病害发病严重的连作区以及典型的轮作区的土壤真菌多样性。结果表明:从群落组成来看,昭通核心烟区土壤真菌群落包括30个门、79个纲、202个目、443个科和976个属,其中子囊菌门为昭通核心烟区土壤真菌群落的绝对优势门,被孢霉属和青霉菌属为昭通核心烟区土壤真菌群落的优势属。群落指示物种分析表明,新烟区土壤真菌群落壳二胞菌属的相对丰度显著高于连作区和轮作区,连作区拟青霉菌属、假裸囊菌属和篮状菌属的相对丰度显著高于新烟区和轮作区烟,轮作区镶刀菌属的相对丰度显著高于新烟区、被孢霉属的相对丰度显著高于连作区。从生物多样性特征来看,新烟区土壤真菌群落的生物多样性最高,物种丰富度显著高于连作区和轮作区;轮作区土壤真菌群落的物种丰富度显著高于连作区,物种均匀度显著低于连作区,真菌群落生物多样性略高于连作区。从真菌群落的功能来看,病理营养型、腐生营养型和腐生—共生营养型的真菌群落为主要组成,新烟区真菌群落占比前1至前3的营养型分别为腐生—共生营养型、腐生营养型和病理营养型,连作区分别为腐生营养型、病理营养型和腐生—共生营养型,轮作区分别为腐生—共生营养型、病理—腐生—共生营养型和腐生营养型。昭通植烟土壤真菌群落组成丰富,新烟区土壤真菌群落的生物多样性最高,物种丰富度显著高于连作区和轮作区,不同类型土壤的真菌群落结构组成差异不显著,轮作有利于降低病理营养型的真菌群落,能减少真菌性病害发生的几率。

Asymmetric Variation in Soil Carbon Emission in Sub-Tropics

Carbon dioxide emission from soil, known as soil respiration, is one of the major sources of the atmospheric carbon. Understanding the relationship between emission rate and the factors associated with the emission process is important in global carbon emission management. The present study investigated soil respiration at three ecologically diverse locations in northern India. CO2 emission was measured in-situ by modified alkali absorption method at three different depths, top-soil (0 cm - 2 cm depth), mid-soil (20 cm depth) and deep-soil (40 cm depth) at each location. Rate of carbon emission from soil varied with location and time. The rate was higher at Riverine Zone (RZ) which had high soil moisture content and profuse ground vegetation compared to Hilly Zone (HZ) containing dry soil and scarce vegetation. The emission rate was also greater in grassland than the plantation area. Rate of carbon emission from soil was heterogeneous along different depths below the ground. Diel variation in emission rate was greater at HZ compared to RZ. Higher microbial population in soil was detected in RZ than HZ. However, the bacterial count out-numbered the fungal count in soils at most places. The study indicates a positive relationship between soil respiration rate and microbial abundance. The fungal population was strongly correlated with CO2 emission rate.

绿农林^(®)41复合微生物菌肥对番茄枯萎病发生和根际土壤 真菌群落的影响

探究绿农林^(®)复合微生物菌肥、番茄枯萎病发生和土壤真菌群落结构的关系,为合理应用微生物制剂绿色防控番茄枯萎病提供理论依据。以往年番茄枯萎病严重发生地块为试验地,分别设置4个处理,清水对照(CK)、绿农林^(®)41复合微生物菌肥(LNL41)、菌肥营养基质(NS)和复合微生物(CM),测定根际土壤养分含量、植株生长、土壤呼吸速率、枯萎病发病率;采用18S rDNA测序技术,探究施用LNL41条件下番茄枯萎病发生及根际土壤真菌群落结构的差异。结果表明:各处理中以LNL41处理效果最显著。LNL41和CM处理的番茄根际土壤中有机质和速效磷含量显著高于其他处理;与对照比较,LNL41、CM和NS处理的株高、茎围、叶面积、光合作用、叶绿素、产量和水溶性糖增幅分别达8.87%~34.71%、15.93%~67.62%、13.37%~52.88%、3.17%~12.55%、3.20%~20.49%、4.38%~19.53%、0.46%~8.79%;LNL41处理的采收期番茄根系土壤呼吸速率提高59.52%,不同生长期的发病率达2.33%~16.33%,防效达80.50%~90.83%;根际土壤真菌属水平Ace指数和Chao1指数分别提高了26.97%~57.71%、24.89%~56.00%,CM处理的多样性指标Simpson指数和Shannon指数明显提高了25.75%~29.45%、39.04%~49.13%,而NS处理的多样性指标有所下降;LNL41处理的肉座菌科和木霉属分别为排名前5的优势科和属(丰度均为8.56%);4个处理中Trichoderma分别与Cladosporium、Uwebraunia、Aureobasidium和Fusarium丰度相似,与Aspergillus和Alternaria呈正相关。LNL41处理的Chao1指数与有机质、速效磷、速效钾和土壤呼吸速率呈显著正相关关系,与盐度和发病率呈显著负相关关系。LNL41处理的腐生营养型功能类群丰度增加了0.92~11.15个百分点,plant pathogen下降了2.55个百分点,endophyte下降了7.95个百分点,而施用NS和CM的处理只有2个功能类群丰度上升。LNL41能显著改善土壤养分比例,进而改善土壤真菌群落结构和功能特性,激发真菌群落腐生营养型功能,促进番茄生长,减少枯萎病的发病率。

Effects of Tillage Depth on Nutrients and Microbial Communities in Tobacco-Planting Soil

The implementation of appropriate tillage practices is of great significance for agricultural production. However, the effects of different tillage depths on soil nutrients content and microbial communities in tobacco-planting soils are still lacking systematic research. In this study, three different tillage depths of 15 cm (T1), 20 cm (T2), and 30 cm (T3) were set up for field experiments in Liupanshui, Guizhou Province, to explore the effects of tillage depth on tobacco-planting soil nutrients and bacterial and fungal communities based on 16S rRNA and ITS sequencing and figure out the key factors affecting soil microbial communities. The results showed that T2 and T3 increased the contents of organic matter, total nitrogen, total phosphorus, available phosphorus, and available potassium in tobacco-planting soil, and increased the diversity of bacterial communities compared with T1. There was no significant difference in the structure of bacterial and fungal communities in different tillage depth treatments, but some dominant genera were significantly enriched in T2 and T3. Desulfobacter, Setophoma, Humicola, and Acremonium were significantly enriched in T2. Chthonomonas and Fusarium were significantly enriched in T3. These genera favor the decomposition of organic matter and the cycling of nutrients, and control soil pests and diseases. Redundancy analysis indicated that TP and AK were the key factors influencing the dominant genera of bacteria and fungi. This study provides a scientific basis for the selection of soil tillage depth for tobacco production in this region.

覆膜对陇东旱地苹果根际土壤化感物质积累与真菌群落特征的影响

【目的】探究果园地膜覆盖对土壤化感物质及真菌群落的影响。【方法】以红富士苹果为研究对象,采用高效液相色谱技术和Illumina高通量测序技术探究了清耕(CK)、覆膜2年(2Y)、覆膜4年(4Y)和覆膜6年(6Y)对苹果树根际0~20 cm和>20~40 cm土层土壤理化性质、化感物质和真菌群落特征的影响。【结果】苹果根际土壤脲酶活性随着覆膜年限的延长而降低。土壤中主要的化感物质的含量总体上随着覆膜年限的延长呈现出降低的趋势。覆膜措施对苹果根际土壤中真菌群落特征具有显著的影响。土壤真菌群落的多样性随着覆膜年限的延长而增高,其中镰刀菌属丰度显著增加。综合对比,覆膜4年的苹果根际土壤中含水量及有机碳、微生物量碳、全氮含量显著增加,较CK分别增加了5.65%~15.00%、3.72%~8.29%、50.16%~64.31%和14.19%~31.44%。β-1,4-木糖苷酶、β-1,4-葡萄糖苷酶和纤维二糖水解酶的活性显著提高,较CK分别增高了78.71%~84.4%、89.01%~97.43%和83.45%~87.68%。并且在0~20 cm的土层中苹果根系的生长量显著提高。与CK相比,根系生物量、根表面积和根体积分别增加了489.84%、533.87%和542.39%。相关性分析结果表明,土壤脲酶、β-1,4-葡萄糖苷酶和香兰素是影响土壤真菌群落的主要环境因子。【结论】覆盖地膜可通过影响苹果根际土壤酶活性和微生物代谢活性,促进土壤碳循环,效果随覆膜年限而异,以覆膜4 a(年)最佳。同时覆膜年限的延长抑制了土壤中植物化感物质的积累,但覆盖年限过长会对土壤真菌群落结构产生不利的影响,因此在生产中,覆膜4 a为西北旱地苹果园适宜的连续覆膜年限。

微生物菌剂对连作芹菜根际土壤真菌群落多样性与结构的影响

以宁南旱区连作4年芹菜根际土壤为研究对象,采用田间定位试验结合高通量测序技术,以常规施肥(CK)为对照,研究常规施肥+枯草·哈茨复合菌剂(MF),常规施肥+枯草芽孢杆菌(BS),常规施肥+哈茨木霉菌(TH)3个处理对芹菜连作根际土壤真菌多样性及群落组成的影响。结果表明:施用枯草·哈茨复合菌显著提高了土壤有效磷、速效钾含量,增幅分别为34.29%和9.98%。施用微生物菌剂增加了土壤脲酶、蔗糖酶活性,平均增幅分别为43.16%和12.98%,并显著改变了土壤真菌的β-多样性。被孢霉属(Mortierella)、织球壳属(Plectosphaerella)、赤霉菌属(Gibberella)、链格孢属(Alternaria)、镰刀菌属(Fusarium)是各处理优势菌属,施用枯草·哈茨复合菌显著降低了赤霉菌属、链格孢属、镰刀霉属等真菌性病原菌的相对丰度,降幅分别为59.88%、51.63%、36.13%。冗余分析表明土壤蔗糖酶、脲酶、碱性磷酸酶活性、pH值和全磷是影响真菌群落结构组成的主要驱动因子。综合而言,枯草·哈茨复合菌剂的施用不仅降低了连作芹菜根际土壤镰刀菌属、链格孢属、赤霉菌属等病原菌的富集,还通过改变有效磷、速效钾等土壤理化性质,进一步重塑土壤真菌群落结构。

天然林改造为单一茶园前后不同生境土壤丛枝菌根真菌物种多样性的差异

在贵州省遵义市正安县和湄潭县,选择地理位置相邻的3种生境类型样地——天然林、由天然林改造而来的人工林、不同种植年限茶园(茶园依据种植年限(t)不同划分为5组:t<10 a、10 a≤t<20 a、20 a≤t<30 a、30 a≤t<40 a、t≥40 a);采用分层随机抽样法设计3种生境的土壤样品采集,共选取37个采样点(茶园17个、天然林10个、人工林10个),统一采集深为5~40 cm的根际土壤,每个样点采集3~5份混合土壤作为重复,共采集128份土壤样品;参照相关标准和规范测定土壤理化性质(pH、有机质质量分数、全氮质量分数、全磷质量分数、全钾质量分数、解氮质量分数、有效磷质量分数、速效钾质量分数、土壤粒径、质地类型),采用湿筛倾注-蔗糖离心法进行土壤丛枝菌根(AM)真菌孢子分离和形态鉴定,采用孢子密度、物种丰富度、分离频度、相对多度、重要值、香农-威纳多样性指数(Shannon-Wiener Index)、辛普森多样性指数(Simpson Index)、皮卢均匀度指数(Pielou’s Evenness Index)评估丛枝菌根真菌群落结构;采用聚类分析法、冗余分析(RDA)法、方差分析法,分析3种生境土壤丛枝菌根真菌物种多样性的差异。结果表明:3种生境中共检出7科11属48种丛枝菌根真菌。孢子密度、物种丰富度、香农-威纳多样性指数、辛普森多样性指数,在天然林土壤中最高、茶园土壤中次之、人工林土壤中最低。种植年限小于20 a的茶园土壤中丛枝菌根真菌物种组成与人工林相似,主要受土壤因子的影响;而种植年限大于20 a的茶园土壤中丛枝菌根真菌物种组成丰富,接近天然林,受土壤因子和宿主植物的双重影响。说明人为因素引起的生境变化会影响丛枝菌根真菌物种组成,扰动后的丛枝菌根真菌生态平衡重建需要一定年限。

不同生产状态下佛手山药土壤微生物群落多样性分析

佛手山药是湖北省“农产品地理标志产品”。大田种植佛手山药有多种生产方式。为了探讨不同生产状态下佛手山药土壤微生物群落结构,进行取样分析。以湖北省武穴市佛手山药主产区佛手山药的土壤样品为研究材料,样品取自于4种不同的自然生产状态(1、施2%阿维菌素连作1年地;2、施2%阿维菌素连作2年地;3、未施2%阿维菌素非连作地;4、未施2%阿维菌素连作2年地)。采取5点取样法分别采集5~10 cm、10~20 cm、20~30 cm深度土壤层土壤,每深度土壤层重复取样3次,并提取土壤基因组DNA;采用细菌16S RNA和真菌ITS技术进行高质量测序。序列数据分析结果表明共获得2539748条真菌ITS有效序列和1964285条细菌16S有效序列。门分类水平上确认了12个真菌分类单元和50个细菌分类单元,属水平共鉴定到193个真菌物种和1023个细菌物种,显示佛手山药根际土壤在不同生产状态下细菌群落组成的差异性相比真菌群落更为明显,连作对真菌群落结构的影响可能超过了施药处理,土壤深度对细菌群落结构的影响可能更为显著。佛手山药土壤真菌和细菌群落结构特征提示在不同自然生长状态和不同生长深度的土壤中,真菌和细菌群落在门和属水平均呈现多样性,佛手山药大田连作种植易增加根部病害发生的风险。

3种混交林造林初期土壤真菌群落结构特征

土壤微生物是参与陆地生态系统生物地球化学循环过程的重要成员。造林可以显著影响土壤微生物群落结构与功能,但造林初期驱动的土壤理化因子变化对土壤微生物结构与功能的影响尚不清楚。通过分析由珍稀乡土树种组成的三种新造混交林(BB:银杏Ginkgo biloba⁃桢楠Phoebe zhennan;CB:香椿Toona sinensis⁃红豆杉Taxus wallichiana⁃桢楠Phoebe zhennan;MB:鹅掌楸Liriodendron chinense⁃乐昌含笑Michelia chapensis⁃香椿Toona sinensis⁃玉兰Yulania denudata)表层(0—20 cm)土壤真菌群落组成、功能类群及其土壤理化因子,并以草灌化未造林地作对照(CK),研究土壤真菌群落结构和功能对不同林型造林初期的响应。结果表明:(1)不同林型土壤真菌群落丰富度、多样性指数高于CK,表现为MB>BB>CB>CK,主要受到土壤孔隙度、水解性氮的影响。(2)土壤真菌门水平优势类群在不同处理间无显著差异,其中子囊菌门占绝对优势,MB中的被孢霉门相对丰度显著高于CK(P<0.05)。与CK相比,球囊菌门与Leptodiscella相对丰度在各林型中均降低。(3)通过非度量多维尺度(NMDS)与置换多元方差(Adonis)分析表明,造林初期,造林土壤真菌群落结构与CK存在显著差异(P<0.01)。冗余分析(RDA)分析表明全钾、水解性氮、土壤容重及土壤碳氮比是影响真菌群落指示种的主要土壤理化因子;被孢霉门与水解性氮、碳氮比、全氮、非毛管孔隙度、含水率均呈正相关,与全钾呈负相关。(4)真菌群落主要以腐生营养型为主,病理营养型次之;造林后腐生营养型真菌相对丰度降低,而土壤腐生菌的相对丰度在BB与MB处理中反而显著增加(P<0.05);MB处理中动物病原菌的相对丰度显著增加(P<0.05);真菌优势功能类群主要受到土壤pH、土壤孔隙度、土壤碳氮比(C/N)、土壤有机质、全氮、全钾的影响。造林初期土壤真菌群落结构与功能类群发生了显著改变,阔阔混交林较针阔混交林变化更加明显,其中多种阔叶树混交林病原菌相对更高。

秸秆还田模式下种植密度对玉米根际土壤真菌群落的影响及其驱动因素分析

秸秆还田和适宜的种植密度有利于改良土壤理化性质,优化微生物群落结构。本研究采用Illumina MiSeq高通量测序技术,在宁夏引黄灌区玉米农田开展连续5a设置裂区试验,探讨不同秸秆还田模式(H1:秸秆粉碎深翻还田、H0:秸秆不还田)和种植密度(D1:67500株·hm^(-2)、D2:82500株·hm^(-2)、D3:97500株·hm^(-2))下玉米成熟期根际土壤真菌多样性、群落结构的变化及其驱动因素。结果表明:(1)秸秆还田模式和种植密度两因素交互效应极显著提高了土壤真菌群落Chao1指数、ACE指数及香农指数(P<0.01),以H1D2处理下最高。(2)农田玉米根际土壤真菌群落主要由子囊菌门(63.50%~81.82%)、担子菌门(4.83%~18.03%)和被孢霉门(3.18%~9.61%)等14个门及509个属的真菌组成,真菌群落组成分析表明,秸秆还田模式各密度处理间群落结构不同,优势菌门和优势菌属相对丰度差异较大。(3)秸秆还田模式和种植密度两因素交互效应极显著降低土壤pH值,提高了有机质、碱解氮及速效磷含量(P<0.01),以H1D2处理下最高。Pearson相关分析表明,土壤pH值、有机质、全氮、全磷、碱解氮、速效磷、速效钾含量与真菌α多样性呈显著或极显著的相关性;土壤pH值与枝孢菌属(Cladosporium)相对丰度呈显著负相关(P<0.05),有机质、全磷、碱解氮、速效钾含量与枝孢菌属(Cladosporium)相对丰度呈显著正相关(P<0.05),有机质含量与毛壳菌属(Chaetomium)相对丰度呈显著负相关(P<0.05)。RDA分析表明全氮、有机质、速效钾和pH值是驱动秸秆还田模式下各密度处理中玉米根际土壤真菌群落变异的主要环境因子。本研究中,秸秆还田结合种植密度82500株·hm^(-2)处理,对提高农田土壤肥力和改善根际土壤真菌多样性最有利。