INTRODUCTION

Urban allotment gardening is currently a growing worldwide phenomenon,especially in industrialized countries(Guitart et al.,2012).The chemical study of topsoil quality along an anthropization gradient has shown that these garden soils may contain metals,especially lead(Pb)(Joimel et al.,2016).Lead is considered to be neurotoxic,even at low concentrations,beginning at 12 µg L−1in the blood(European food safety norm).Thus,high Pb concentrations could induce health risks through the consumption of contaminated vegetables from allotment gardens.Lead contamination results not only from human activities such as industry,car traffic,and refuse(El Khalil et al.,2013;Huot et al.,2013)but also from intensive gardening practices,such as the use of pesticides containing Pb(Belon et al.,2012).The presence of metals,such as Pb,may also be of geogenic origin,resulting from metalliferous mineralization,inducing local naturally high concentrations in soils(Bourennane et al.,2010;Ander et al.,2013).However,urban vegetable garden soils usually also have a basic pH and a high rate of organic matter(Joimel et al.,2016),contributing to reduced Pb mobility.This assumption is especially true for geogenic Pb,which is often considered to present lower bioavailability than anthropogenic Pb.

Recent soil analyses,performed in 2011 and 2012 on allotment gardens in Nantes(France)(Bouquet et al.,2017),found elevated Pb concentrations averaging 170 mg kg−1,mainly of geogenic origin due to the alteration of a particular parent rock,rich in Pbbearing minerals(Jean-Soro et al.,2015).Despite Pb being primarily of geogenic origin and presenting moderate anomaly(2.5-times higher than background levels)(Bouquet et al.,2017),health risks have been demonstrated due to the consumption of contaminated vegetables from these allotment gardens,with the Pb concentrations in leeks,cabbage,and carrots exceeding the European regulatory standards by up to 25 times(Jean-Soro et al.,2015).

These results raise questions as to the effects of moderate anomalies in geogenic Pb on the soil biota.In fact,metals,such as Pb,could also affect soil organisms,thereby inducing a decrease both in biodiversity and in soil biological activity(Giller et al.,1998),which are important factors in the provision of ecosystem services,such as food production(Scheu,2003).Anthropogenic Pb contamination is often accused of impacting the soil fauna by inducing a decrease either in biodiversity or in the biological activity of some soil fauna groups,such as macrofauna(Nahmani et al.,2003),collembolans(Fountain and Hopkin,2004a),and nematodes(Campos-Herrera et al.,2016;Guti´errez et al.,2016).

However,to date,numerous studies have only concerned the effects of anthropogenic Pb contamination and/or elevated geogenic Pb concentrations(higher than 1000 mg kg−1soil)(Russell and Alberti,1998).In contrast,the effects of moderate geogenic Pb anomalies on soil fauna have as yet been scarcely studied.

The relationships between metal in the soil and fungi communities have been widely explored,but results of the studies trying to establish the effect of metal toxicity to soil microorganisms vary greatly(Giller et al.,1998).The increase in studies of the effects of metals on soil microorganisms is related to an increasing awareness of pollution issues(B˚a˚ath,1989).A shift in a fungi species’composition induced by Pb contamination was found when Pb was present with Cd,Cu,and Zn as well as for Zn and Cd alone(B˚a˚ath,1989).A-gain,major gaps in knowledge and theory exist as to how the microorganisms are exposed and respond to the metals in soils(Giller et al.,2009).

Among the soil fauna,collembolans are a key component of the food web and play a key role both in litter decomposition(Cortet et al.,2003)and nitrogen and carbon cycling(Filser,2002)as well as in soil microaggregation,and,therefore,in soil productivity as a whole.The primary role of collembolan is decomposition and the way the soil functions because they feed on detritus and/or fungi(O’Brien et al.,2005).In addition,soil fungi are partly in fluenced by collembolan grazing activity.

Species richness varied between 5 and 10 species per plot,with 8 species on an average.Analysis of the fungal structure community revealed two clusters with 64.5%of similitude(Fig.2).These two clusters were related to total Pb concentration.The first group included sub-plots with low Pb concentrations(＜197 mg kg−1),except for Sub-plot 6(204 mg kg−1).The second group was composed of sub-plots with higher Pb concentrations(＞ 197 mg kg−1),except for Sub-plot 20(176 mg kg−1).The species richness,Shannon diversity index,and evenness index of fungal communities were not correlated to total and CaCl2-extractable Pb concentrations or to pH(Table III).

Our study focuses on an allotment garden,which presents a local geogenic Pb anomaly with concentrations ranging from 97 to 314 mg kg−1soil,which consequently induces Pb contamination in the vegetables consumed by gardeners(Jean-Soro et al.,2015).Within this framework,our objective was to evaluate the effect of this geogenic anomaly on collembolan and fungal communities.A single garden on an urban allotment with a pronounced Pb gradient was studied.We hypothesized that the total Pb concentration induced a direct chemical constraint on soil fauna that reduces the relative abundance of taxa exhibiting traits linked to Pb exposure(body length and localization in soil pro file),avoidance(motion strategy),population recovery(reproduction type),and/or an indirect effect as a result of the change in the structure of the fungal community.

MATERIALS AND METHODS

Experimental site and soil characteristics at plot scale

An experiment was carried out on a 280-m2individual plot at the Eglantiers allotment garden located in Nantes(Loire-Atlantique,France).The climate is temperate oceanic with a mean temperature of 12°C and a mean rainfall of 820 mm per year.At the beginning,the garden plot was divided into two sub-plots.Soil analysis was performed in autumn 2012.Twenty subsamples of cultivated topsoils(0–20 cm)were collected from each sub-plot and then mixed and homogenized to obtain two representative samples.Few differences were noticed in the main soil characteristics analyzed(Table I).The soil had a sandy loam texture and high nutrient contents.Its mineralogy mainly consisted of quartz(71%);feldspars such as orthoclase(9%)and plagioclase(8%);phyllosilicates such as kaolinite(6%);and traces of chlorite and illite or micas(6%).Cd,Cu,and Zn were not considered as possible contaminants in this garden,conversely to the usually observed levels in urban vegetable gardens(Joimel et al.,2016).

In contrast,Pb was the major concern in this allotment garden,with a median of 171 mg kg−1,which was considered as highly anomalous compared to usual Pb concentrations both in French soils in general(Baize et al.,2008)and particularly in the district(Le Guern et al.,2013a,b).Lead in this garden is known to be geogenic,probably linked to mineralized veins rich in Pbbearing minerals in the parent material,which is constituted of mica schists(Jean-Soro et al.,2015).Lead speciation in the garden was also assessed through sequential extraction(Ure,1996)following the Community Bureau of Reference(BCR)procedure(Bouquet et al.,2017).Four fractions were obtained∶exchangeable Pb(1.2%),Pb linked to the oxy/hydroxides of Mn and Fe(11.9%),Pb linked to sul fides and organic matter(4.6%),and the residual fraction(82%).

TABLE I Topsoil characteristics of an urban vegetable garden at the garden plot scale(values for two replicates,which were derived from 20 sub-replicates each)and sub-plot scale(32 sub-plots)

a)Joimel(2015). b)Jean-Soro et al.(2014). c)B´echet et al.(2018).

Characteristics Scale Plot Sub-plot Sand(%) 57,58a)Silt(%) 28,28a)Clay(%) 13,14a)pH 7.4,7.4a) 5.75–7.63b)Organic matter(g kg−1) 36,29a)C:N 14,13a)CEC(cmol+kg−1) 8.7,7.4a)Total Pb(mg kg−1) 133,208c) 97–314b),c)Total Cu(mg kg−1) 38,28c)Total Zn(mg kg−1) 94,79c)Total Cd(mg kg−1) 0.15,0.12c)CaCl2-extractable Pb(µg kg−1) 34–285b)

Soil characteristics at sub-plot scale

In order to study the variations in Pb concentration at plot scale in greater detail,the garden was divided into 32 sub-plots of 6 m2each separated by 50-cm wide grass strips(Fig.1).Total Pb,CaCl2-extractable Pb,and pH were analyzed in each of the 32 sub-plots.Total Pb concentrations ranged from 97 to 314 mg kg−1,with a median of 197 mg kg−1(Jean-Soro et al.,2015).These values increased along the west-east gradient.Values of CaCl2-extractable Pb and pH also varied according to this gradient.

Fig.1 Distribution of total Pb concentrations(values in the parentheses)in the soil of urban vegetable garden(modified from B´echet et al.,2016).The garden plot was divided into 32 sub-plots of 6 m2each separated by 50-cm wide grass strips.Q=quartile.

Pearson’s test was again used to assess the correlations of the parameters describing fungal and collembolan communities with the Pb concentration gradient.

Soil fungi diversity sampling at sub-plot scale

管理体系的缺陷使得管理出现诸多问题，对出现的问题可能应付不了，影响正常工作的进行。检测机构要建立独立的安全工器具管理体系，并不断的进行完善，确保管理的有效性。对于有电网监督系统的电力企业，要取消县级供电单位的检测职能，对电力工器具的检测由质检中心负责，这样将有利于安全工器具的统一管理。如果一定要保留县级供电企业工器具检测结构，一定要对其进行考核，获得相应的资质，最好是获得权威机构的认可。对于发电系统的供电企业，可自身进行预防性试验或者让其他有资质的检测机构进行试验，这样确保电力工器具管理质量。

Fungal DNA diversity analysis

The fungal community structure was studied using polymerase chain reaction-temporal temperature gel electrophoresis(PCR-TTGE).DNA was extracted from soil samples(0.5 g)using the Nucleospin®soil kit(Macherey-Nagel GmbH&Co,D¨uren,Germany).Before DNA analyses,soil samples were ground using a mixer mill(MM 400,Retsch,Haan,Germany)three times for a period of 30 s each at a frequency of 25 Hz.The extracted DNA was quantified,and its quality was controlled using SPECTROstar Nano(BMG LABTECH LVi Plate,Offenburg,Germany).The 5.8S DNA region was amplified using ITS5-gc(forward)and ITS2(reverse)primers(Joly et al.,2012).The final reaction volume totaling to 50 µL comprised 1.2 ng L−1 of DNA template,0.3 mol L−1of each primer,200 mol L−1of dNTPs,0.012 unit(U)L−1of Taq polymerase,1× reaction buffer,2.5 mmol L−1of MgCl2,and 500 ng L−1of bovine serum albumin.The cycling conditions were set as follows∶1 cycle at 95 °C for 15 min,followed by 35 cycles of 95°C for 30 s,55°C for 45 s,and 72 °C for 30 s,and a final extension cycle at 72°C for 7 min(CFX96 TouchTM,Thermal Cycler,Bio-Rad,USA).Analyses of TTGE were performed using a DCodeTMsystem(Bio-Rad,Hercules,USA).The polyacrylamide gel(9.5%)(volume∶volume)was composed of two parts∶the upper,urea-free,“concentration”(stacking gel)of about 1 cm upward from the base of the wells,and the lower, “denaturation”part(resolving gel),at 8 mol L−1urea.Fifteen microliters of PCR products were deposited in each well.Migration was performed in Tris-acetate-EDTA 1.25×buffer for 750 min at 50 V,with a temperature gradient from 65 to 70°C,i.e.,increasing the temperature at the rate of 0.4 °C h−1.The gels were stained using GelRedTM(Biotium,Hayward,USA)and then imaged under ultraviolet(UV)light(Molecular Imager®Gel DocTMXR System and Image LabTMSoftware,Bio-Rad,Hercules,USA).Microbial community structure analysis was performed from genetic fingerprints.

Fungal communities were described by composition,richness(mean number of taxa per sample),Shannon diversity index,and evenness index(diversity and distribution index per sample).

为了估计由教育、培训和工作经验等学习过程形成的人力资本投资回报，常使用明瑟收入函数方法[4]。明瑟收入函数将工资收入同通过学习过程获取的人力资本联系起来，被表达为在一个特殊学习环境中所用年限的线性函数，知识和技能的逐渐贬值可通过人力资本折旧得以说明[5]。为了回答教育投资是否足够多，以及政府应该给予多少教育补贴。经验工作更强调教育收益率的精确测量，承认人们之间在学习能力方面存在差别。这些差别既影响教育投资的最优数量，也影响教育投资的最优回报，构建一个测量教育收益率的内生决定模型，要求构建合适的统计方法。

Collembolan diversity sampling at sub-plot scale

（2）起重机载荷值：计算框架或刚架时，多台起重机的垂直载荷和水平载荷的标准值应乘以载荷规范规定的缩减系数；当要定义起重机时，程序将在分析过程中以双层起重机的特殊方式组合，并获得正确的计算结果。否则，起重机的组合负荷值将太大，并且用于结构构件的钢的量将相应地大。

Collembolans were sampled in April 2013.Among the garden plots,24 replicates were randomly sampled along the concentration gradient(Fig.1).One sample of intact soil core(5 cm depth and 6 cm diameter)was collected per replicate.

Collembolan diversity analysis

Collembolans were extracted from soil samples using a high-gradient McFadyen extractor for one week(Petersen et al.,2003).Except for Mesaphorura,identified only at the genus level,collembolans were identified at the species level using various available dichotomous keys(Gisin,1943;Zimdars and Dunger,1995;Dunger,1999;Potapow,2001;Thibaud et al.,2004;Hopkin,2007;Dunger and Schlitt,2011;Jordana,2012).

For the taxonomic approach,collembolan communities were described by density(abundance of each taxon per m2,richness(mean number of taxa per sample),Shannon diversity index,and evenness index(diversity and distribution index per sample).

For the functional approach,8 functional traits and ecological performances were selected for their ability to reflect the effect of Pb exposure or avoidance on population recovery(Table II).Body shape,body length,visual organs,and pigmentation are related to the vertical distribution of collembolans in the soil(Ponge et al.,2006;Farsk´a et al.,2014;Salmon et al.,2014).Reproduction type is related to their ability to colonize or survive after disturbances(Chernova et al.,2010).Motion strategy determines the ability of collembolan to jump using its furcula,e.g.,to avoid predators.The ability to jump is defined by the presence of a short,reduced,or long furcula.Habitat and microhabitat indicate ecological preference and trophic strategy(Salmon et al.,2014).

Fungi were sampled in April 2013.Among the 32 sub-plots,twelve replicates were randomly sampled along the concentration gradient(Fig.1).Fifty grams of litter-free topsoil were collected from each of the subplots selected.

基于网络技术的飞速发展，大数据下的会计信息化为企业带来便利的同时，其存在的诸多问题阻碍着会计信息化的发展，甚至给企业带来不可估量的经济损失。

Traits were obtained from the BETSI(biological and ecological functional traits of soil invertebrates)database on functional traits(CESAB/FRB)(Pey et al.,2014a).Data on functional traits were primarily adopted from identification keys in the literature(Gisin,1943;Zimdars and Dunger,1995;Dunger,1999;Potapow,2001;Thibaud et al.,2004;Hopkin,2007;Dunger and Schlitt,2011;Jordana,2012).The trait matrix contained trait attribute scores,encoded using a fuzzy method(Chevene et al.,1994)and adapted to soil organisms(Hedde et al.,2013).Briefly,a species affinity percentage for each attribute of a trait was determined per source and then averaged through the sources to obtain the mean distribution of species affinity across the different attributes of a trait(i.e.,the species trait pro file).

In order to study the repartition of traits within the communities,we calculated the community weighted mean(CWM)for each trait.Community weighted mean is the sum of species trait pro files weighted by their relative abundance in the community(Lavorel et al.,2008).The multidimensional functional structure of collembolan communities was characterized by three distance-based functional diversity indices(Lalibert´e and Legendre,2010),viz.,functional richness(FRic),functional evenness(FEve),and functional divergence(FDiv),and Rao’s quadratic entropy(RaoQ).These indices quantify different facets of the functional diversity for a community(Vill´eger et al.,2008);FRic represents the volume of the functional space occupied by a community,FEve corresponds to the regularity of the distribution of species abundance in a given volume,and FDiv is the divergence in the distribution of abundance in this volume(Laliberte and Legendre,2010).In addition,we used the RaoQ index,which incorporates both the relative abundance of a species and a measure of the pairwise functional differences between the species(Botta-Duk´at,2005).The RaoQ index is a suitable approach to measure functional diversity,where several traits are considered(Pelosi et al.,2014).The maximum functional dissimilarity within the collembolan community was observed at a value of 1.

Statistics

The effects of Pb concentrations on fungi and collembolan communities were investigated.Pearson’s test was used to compare TTGE pro files between the fungi communities.The unweighted pair group method with an arithmetic mean(UPGMA)was used to construct a dendrogram from similarity coefficients(Ibekwe et al.,2010).

Total collembolan density in the soil samples ran-ged from about 19×103to 505×103individuals m−2(Table IV).Other parameters also ranged widely.On an average,there were ten species,with the Shannon diversity index of 1.5 and evenness index of 0.6 per sub-plot.The first two axes of PCoA for collembolan species composition represented 51%of the total inertia(Fig.3).The collembolan species composition varied depending on the sub-plot considered.No defined response to soil parameters,such as Pb concentration,was observed.The number of species,Shannon diversity index,evenness index,and density of collembolan communities were not correlated to total and CaCl2-extractable Pb concentrations and to pH.

Total Pb level of each sub-plot was analyzed using a portable X-ray fluorescence tool(Niton 792).A selection of soil samples set for laboratory analysis by inductively coupled plasma mass spectrometry(ICP/MS)was obtained to calibrate the device.This method provides a semi-quantitative analysis of Pb concentrations,with a detection threshold of 4 mg kg−1(in a SiO2matrix).Blank tests and internal quality control samples were introduced into each series.The quality of the analyses was assessed by analyzing a reference soil,BCR-7002,using the same procedure.The quantification threshold was 0.1 µg L−1for Pb.Soil samples were dried for 5 d at 40°C and prepared according to the NF ISO 11464 standard(AFNOR,2006).Soil pH was measured according to the NF ISO 10390 standard(AFNOR,1994),and mobile Pb was extracted with 0.01 mol L−1CaCl2for 2 h according to the NEN 5704 standard(1996).

TABLE II Description and attributes of morphological,behavioral,and physiological traits considered for the trait-based approach of the collembolan community

Trait Abbreviation Attributes Body shape BSH Spherical,cylindrical Body length BLR ＜ 1,1–2,2–3,＞ 3 mm Motion strategy MS With,without furcula Pigmentation PIG With,without coloration Visual organ VO With,without ocelli Reproduction REP Sexual,asexual Habitat HABI Forest,agricultural,anthropogenic areas Microhabitat MHABI Organic matter in decomposition,mineral soil,vegetation

The significance level for all analyses was fixed at the rejection level of P=0.05.Analyses of TTGE profile were performed with FPQuestTMsoftware(Bio-Rad,Hercules,USA).Fungal community structure analysis was performed from genetic fingerprints.All statistical analyses for collembolan communities were performed using R software version 3.2.2(R Development Core Team,2015)with vegan packages(Oksanen et al.,2014)for the taxonomic approach and the FD package(Lalibert´e and Legendre,2010)for the functional approach.The ade4 package(Thioulouse et al.,1997)was used for multivariate analysis.All data mentioned in the results are mean values.

RESULTS

Fungi

Relationships between metal in the soil and collembolan communities have mainly been explored using taxonomic approaches(including species richness,abundance,and community structure and composition).A functional trait-based approach would be complementary to these approaches because traits are properties of individuals that govern the responses to their environment(Pey et al.,2014b).For invertebrates,Pey et al.(2014b)defined a functional trait as being any morphological,physiological,phenological,or behavioral(MPPB)feature measurable at the individual level,without reference to any other level of organization.Over the last 20 years,functional trait investigations have contributed to highlighting the way in which environmental stressors impact plant selection(Lavorel and Garnier,2002;Garnier et al.,2007)and more recently have included the effects on soil fauna too(Hedde et al.,2012;Santorufo et al.,2014a).For example,a study of the functional traits of ground beetles has shown their sensitivity to anthropogenic Zn contamination(Skalski et al.,2010).

Taxonomic composition and structural collembolan communities

A total of 26 taxa were found in the garden topsoil,belonging to nine families,Brachystomellidae,Entomobryidae,Hypogastruridae,Isotomidae,Neelidae,Onychiuridae,Sminthuridae,Sminthurididae and Tullbergiidae.Three species were singletons and six species were doubletons.The most abundant species were Proisotoma minuta(Tullberg,1871)(36%),Parisotoma notabilis(Schaeffer,1896)(29%),and Folsomia similis(Bagnall,1939)(18%).Species with lower abundances were Protaphorura armata(Tullberg,1869)and Entomobrya multifasciata(Tullberg,1871).Mesaphorura sp.was also a frequent taxon.

Fig.2 Similarity between the fungi community of each sub-plot in garden soil along the gradient of total Pb concentration increasein soil.Q=quartile.

TABLE III Species richness,Shannon diversity index,and evenness index of fungal community and Pearson’s correlation coefficients(r)with total Pb,CaCl2-extractable Pb,and pH in garden soil

a)Min.=minimum.b)Max.=maximum.c)Not significant.

Parameter Min.a) Max.b) Mean r Total Pb CaCl2-extractable Pb pH Species richness 5 10 7.8 −0.20nsc) −0.30ns 0.48ns Shannon diversity index 1.1 2.1 1.8 −0.40ns −0.31ns 0.20ns Evenness index 0.4 0.6 0.6 −0.48 ns −0.22ns −0.11ns

We analyzed the effect of Pb on the specific composition of collembolans by performing a principal coordinate analysis(PCoA)using the Bray-Curtis index to explore dissimilarities between the communities.The CWM values were compiled into a single matrix(26 taxa×16 CWM).Then,we performed principal component analysis(PCA)to investigate the functional composition of collembolan communities.For binary attributes,only one attribute per taxa was used in PCA to avoid auto-correlation.Moreover,each variable in PCA was weighted by the number of attributes for each functional trait.

TABLE IV Species richness,Shannon diversity index,evenness index,and density of collembolan community and Pearson’s correlation coefficients(r)with total Pb,CaCl2-extractablePb,and pH in garden soil

a)Min.=minimum.b)Max.=maximum.c)Not significant.

Parameter Min.a) Max.b) Mean r Total Pb CaCl2-extractable Pb pH Species richness 6 13 10 −0.38nsc) 0.06ns −0.16ns Shannon diversity index 0.6 2.1 1.5 −0.35ns −0.29ns 0.18ns Evenness index 0.3 0.8 0.6 −0.22ns −0.32ns 0.25ns Density(× 103individuals m−2) 19 505 123 0.03ns 0.21ns −0.36ns

Fig.3 Principal coordinate analysis(PCoA)of the specific composition of collembolans in garden soil along the gradient of total Pb concentration increase(4th quartile(Q)＞3rd Q＞2nd Q＞1st Q)in soil.

Functional parameters of collembolan communities

Based on CWM values,the main characteristics of collembolan communities were small bodied(1–2 mm)(CWM=76%),cylindrical(CWM=99%),with ocelli(CWM=85%),with furcula(CWM=90%),pigmented(CWM=61%),and with sexual reproduction(CWM=74%).Concerning the ecological preferences for habitat,CWM values were 52%for forest,28%for anthropogenic,and 19%for agricultural habitats.For microhabitat,CWM values were 7%for vegetation and 44%and 48%for decomposing organic matter and mineral soil,respectively.

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The first two axes of PCA on CWM represented 68%of the total variability(Fig.4).Axis 1 seemed to be related to species habitat and microhabitat preferences.Axis 2 represented an opposition between the organisms presenting pigmentation,ocelli,furcula,spherical body,and body length＞2 mm living in a vegetation microhabitat.The trait pro file for Sub-plot 26 presented a higher differentiation than that of the other sub-plots.

However,two functional parameters of collembolan communities were significantly correlated to total Pb concentrations(Table V),viz.,FRic and the RaoQ index,which significantly decreased as total soil Pb concentration increased.Concerning other indices and soil parameters,no significant relationship was observed,even if a tendency existed along the gradient towards a decrease in FEve.

TABLE V Functional richness(FRic),functional divergence(FDiv),functional evenness(FEve),and Rao’s quadratic entropy(RaoQ)of collembolan community and Pearson’s correlation coefficients(r)with total Pb,CaCl2-extractable Pb,and pH in garden soil

*Significant at P＜0.05.a)Not significant.

Para-Mean r meter Total Pb CaCl2-extractable Pb pH FRic 8.06× 10−5−0.41* −0.17nsa) −0.19ns FDiv 0.78 −0.07ns 0.24ns −0.25ns FEve 0.53 −0.31ns −0.02ns −0.05ns RaoQ 0.03 −0.43* −0.37ns 0.18ns

Fig.4 Principal component analysis(PCA)of functional composition of collembolans based on values of community weighted mean(CMW)for 8 traits(a)in the 26 sub-plots of garden soil(b)(26 taxa,24 CWM).Labels in Fig.4b correspond to plot numbers along the decrease in total Pb concentration in soil.VO abs=visual organ,without ocelli;BSHsphe=body shape,spherical;BLR＜1,BLR 1-2,BLR 2-3,and BLR ＞3=body length,＜ 1,1–2,2–3 or＞ 3 mm,respectively;PIGwith=pigmentation,with coloration;REPasex=parthogenesis reproduction;HABI fore,HABI agri,and HABIanth=forest,agricultural,anthropogenic habitats,respectively;MHABIorga,MHABI mine,and MHABIvege=microhabitat,organic matter in decomposition,mineral soil,and vegetation,respectively;MSwith=motion strategy,with furcula.

DISCUSSION

Numerous studies have dealt with the effect of anthropogenic Pb contamination on the microfauna and microorganisms,but only a few relate to geogenic Pb.Yet,environmental and sanitary risks do indeed exist,even with this geogenic Pb.In the present study,we investigated the effect of a moderate geogenic Pb anomaly in an urban vegetable garden on fungi,using a genetic fingerprinting method,as well as on its collembolan communities,using taxonomic and trait-based approaches.

低氧微环境中过表达AQP9可抑制人肝癌SMMC-7721和Huh-7细胞的增殖(钱妍至)(3):204

Our results showed that geogenic Pb affected the composition of fungi communities.These results could be related to the potential toxicity of metals,as previously reported for anthropogenic metals on soil microorganisms(Giller et al.,1998),in particular on fungal diversity(Yang et al.,2015).The review of B˚a˚ath(1989)regarding the effects of metals on microbial populations noted,in numerous investigations,a reduction in both the abundance and biomass of fungi due to metals,often with a selection of tolerant species,but no clear effect on the number of taxa(or colony forming unit).Other effects on fungal biodiversity could be related to accumulation of metals in the fungal hyphae.However,in the present study,no correlation was demonstrated between the taxonomic parameters of fungi communities and total or extractable Pb.These contrasting results could also be induced by the in fluence of other factors such as vegetation or cultivation practices.Several factors have been reported that in fluence the whole vegetable garden(Chenot et al.,2012)and,perhaps,soil biodiversity.

The collembolan community interacts with soil fungi within the soil food web.The metals in soil are largely transferred to and accumulated in collembolans,which are known to feed on fungi.To maximize their fitness,collembolans are able to adjust the proportion of food material they ingest(Scheu and Folger,2004).In addition,collembolans can discriminate between fungal mycelium grown on a metal-contaminated medium and a medium that is not metal-contaminated(Pfeffer et al.,2010).Therefore,a Pb-related modification to fungal communities may,in turn,have affected collembolan communities.

至于爱情，葛优在普及喜马拉雅山南麓的知识时，那严肃又带有一点幽默感的样子，正是很多人事业刚有气色时的写照。自我感觉一切运筹帷幄，有安全感，对异性可以毫无顾虑地展现属于男人的魅力！后面在飞机上发生紧急情况的时候，一切又都变得无所谓，这时只想和亲爱的她共度难关。他们不仅帮别人实现了梦想，同样也实现自己的人生目标，这样的叙事让观众产生了共鸣。这样成功的例子有很多。比如小成本的电影《疯狂的石头》等。

人力资源管理工作是当前社会学工作的重要组成部分，它是指企事业单位遵循科学的原则，对于本单位的人力资源进行合理分工，同时通过一系列措施来调动每一位员工的积极性，尽量做到人尽其才物尽其用，最终促进自身的良性发展。在学校工作中，各类工作繁琐，且因为工作对象是人，容易出现各类突发性的问题，所以学校人力资源管理工作也是非常重要的工作。在学校人力资源管理中，也要树立全局意识和整体意识，科学、规范地落实各项岗位评价、奖励机制，使每一位教职员工能够爱岗敬业，尽职尽责。对此，孙中山先生曾说：“人能尽其才则百事兴。”因此，对于人才管理工作必须要充分重视。下面，我就学校的人力资源管理谈几点自己的看法和体会。

In the vegetable garden,as 83%of the total collembolan abundance comprised only three species,the evenness index was low.This dominance of a few species in the collembolan community structure is often related to highly disturbed or contaminated sites(Russell and Alberti,1998).Among the three abundant species,P.minuta and P.notabilis are widely distributed and frequently dominant in soils,including urban soils(Kuznetsova,2003;Santorufo et al.,2014a).P.minuta predominance may be due both to the preference of this species for manure,which is widely used for managing garden soil fertility,and its high tolerance to stress(Santorufo et al.,2015).Although F.similis is rarely observed in Europe,it has been already noticed in garden soils.In this context,its relatively high abundance is not surprising,since the species is associated with composts(Gisin,1943;Hopkin,2007),which are widely present in gardens.The abundances of a dominant species and the evenness index were not,however,related to the soil Pb concentration.The hypothesis that the selection of tolerant taxa is associated to the conservation of more sensitive species at low abundance,involving a decrease in evenness(Fountain and Hopkin,2004b),was not proven in the present study.However,the evenness index was very low across the whole garden,which could indicate that the index was not sensitive along a gradient but only to marked differences in metal concentration.Thus,in our study,the taxonomic diversity of collembolan species was not altered by higher geogenic Pb concentrations(total and extractable).This result is in accordance with previous studies on anthropogenic metals.For example,Winkler(2014)showed that,in a forest contaminated by various metals,including Pb,collembolan species richness was almost the same in both metal-polluted and control forests.In contrast,Santorufo et al.(2012,2014a)demonstrated a correlation between a decrease in species number and increased concentrations of Cu,Pb,and Zn.However,our garden soil had a lower metal concentration than those of soils from other studies conducted in urban environments on anthropogenic Pb alone(i.e.,higher than 200 mg kg−1of anthropogenic Pb in Santorufo et al.,2012).

Moreover,even if collembolans feed mostly on fungi(Pollierer et al.,2012),they can also feed on organic matter such as feces(Ponge,1991).The high organic matter content in garden soil(Joimel et al.,2016),often imported from non-contaminated sites,could provide a variety of food resources for collembolans,potentially allowing collembolan communities to avoid the negative effects of metal.

However,although there were differences between the community compositions of each sub-plot,no clear relationship between taxonomic composition and Pb or pH was observed.This shift in species distribution indicates the divergent responses of the community structure to their soil habitat.

Our results also showed an effect of geogenic Pb concentrations,but no effect of pH,on the functional structure and composition of collembolan communities.

According to the functional trait-based approach,most collembolans in the garden shared a common trait pro file,i.e.,small-bodied(＜2 mm),cylindrical,pigmented,and with ocelli,furcula,and sexual reproduction.Santorufo et al.(2014a)observed that the species most tolerant to urban environmental conditions,often in multi-contaminated soil,had a small body size,jumping motion strategy,sexual reproduction,and pigmentation.Furthermore,in our results,FRic and FDiv indices decreased along the gradient of total Pb concentration increase,indicating a clear trend for species to share the same traits when Pb concentrations increase.

其中T2=1.73×σk，σk为邻域内方差[5]。T2的作用在于将噪声分类，若判断为高斯噪声采用均值滤波，判断为脉冲噪声则用中值滤波。阈值T1的选取是针对图像出现类似只有一个象素宽的细微纹理。T1一般取6～10之间的整数，本文中取8。

Higher pigmentation protects the organisms from UV radiation(Hopkin,2007),whilst allowing sexual identification(Santorufo et al.,2015),thereby permitting organisms to survive on the surface.These organisms also have a high mobility owing to furcula and ocelli,thereby pointing to the ability of these organisms to avoid contamination.Natal da Luz et al.(2004)demonstrated the use of avoidance behavior by Folsomia candida in highly contaminated soils.Austruy et al.(2016)con firmed these exclusion/avoidance mechanisms for Pb in the case of highly polluted soils or soils with low metal bioavailability.Geogenic contamination often occurs at low bioavailability,which could explain the shifts in functional pro files along the contamination gradient.

Sexual reproduction could also represent an advantage over asexual reproduction in contaminated soil.Gillet and Ponge(2003)noted that Mesaphorura macrochaeta,a parthenogenic collembolan,can switch to sexual reproduction in soil polluted by Zn.

In fact,the increased proportion of individuals with pigmentation,furcula,or ocelli is related to the selection of epigeic organisms(Salmon et al.,2014),which are less sensitive to environmental stress(Kærsgaard et al.,2004).These characteristics are more frequently observed in open habitats,such as vineyards and arable soils(Auclerc et al.,2009),and could also occur in vegetable gardens.Furthermore,this selection could be due to the advantages of epidaphic collembolans vs.eudaphic collembolans,which more frequently live in contact with more deeply contaminated soils.

The taxonomic approach provided no indication of the degree of Pb concentration,whereas changes in morphological traits and ecological preferences were indeed observed.Moreover,it seemed that the taxonomic indices of the fungal communities were less sensitive than fungal composition.This underlines the idea put forward by Ladygina et al.(2008)that it is not possible to detect responses to stress using general methods(e.g.,determining the microbial biomass or numbers of collembolans)to determine food web components.In contrast,functional traits provide information on the community responses to Pb concentration effects,even if the concentration is moderate.

Finally,all these results highlight both a direct and perhaps an indirect effect of total geogenic Pb on soil biota.However,no relationship was reported with extractable Pb,which could be explained by its low bioavailability.Similarly,the geogenic Pb transferred to vegetables(Jean-Soro et al.,2015)was not clearly related to extractible Pb.However,it should be noted that the geogenic origin of Pb does not prevent its accumulation by vegetables or by soil biota.Indeed,the relationship between soil biota and extractable Pb or other metals is often complex.Some studies on collembolan failed to determine its relationship with extractable Pb(Santorufo et al.,2014b),whereas another study demonstrated the opposite(Luo et al.,2014).Beaumelle et al.(2014)mentioned this lack of genericity when studying the response of earthworms to moderately and multi-contaminated soils.Many other parameters could be involved and affect the relationship,in particular the divergent effects of different metals and complexity of soil textures(Beaumelle et al.,2014).

There is still no universally acceptable method for assessing soil bioavailable metal concentrations(Giller et al.,2009),and our results further highlight the need for reliable indicators to predict the effects of metals on soil biota,especially in case of moderate or geogenic contamination.

劈山填海造地场区钻孔灌注桩护筒埋设的探讨…………………………………… 李天生，郑权恒，王玉军（1-83）

延伸组随访期间生活质量评分（89.2±7.5）分，对照组随访期间生活质量评分（67.5±5.4）分，延伸组随访期间生活质量评分显著高于于对照组，组间对比，差异有统计学意义（P＜0.05）。

首先，可以唤起全社会对于历史先贤和优秀传统文化的重视。世界上大部分国家，对自己国家和民族的优秀人物都有特别的纪念日，许多国家甚至把这些人物印刷在钱币上面。

CONCLUSIONS

The geogenic origin of Pb,even at moderate concentrations,does not prevent it from affecting the soil biota.These effects cause modifications to the fungal community and to the functional traits of collembolan communities.Indices based on functional structure,such as functional traits,are more sensitive than those based on taxonomic structure,when used to study the effect of Pb,even of geogenic origin.These indicators could also be used to better understand the relationship between organisms in soil food web.

ACKNOWLEDGEMENTS

We would like to thank the gardeners and all the partners involved in the JASSUR program for their substantial help,particularly Dr.Armelle Braud and Alain Rakoto.This work was supported by the ANR(French National Agency of Research,JASSUR research project;ANR-12-VBDU-0011).The authors wish to thank their colleagues from the BETSI project(FRB-CESAB)for their work on functional traits.

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