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1.
The soil provides a great variety of microhabitats for myriad organisms of different size, physiological activity, behavior and ecosystem function. Besides abundance of participating soil organisms, their species diversity facilitates maximum exploitation of the resources available in the different habitats. At various levels of resolution, species can be categorized into classes performing ecosystem functions and, within each functional class, into guilds of species with similar life course characteristics. Measurement of the diversity and abundance of species within a functional class provides insights into the nature of ecosystem functions and services and to the health of the soil. At higher resolution, species diversity within guilds of a functional class may infer the degree of exploitation of available resources and the complementarity of an ecosystem service; diversity among the guilds of a functional class may indicate successional complementarity of the services. A diversity of guilds within a functional class expands the range of conditions over which ecosystem services are performed while species diversity within a functional class and its guilds contributes to the magnitude of the services. Consequently, diversity of species within functional classes is a key element of the biological component of soil health. In the context of ecosystem services and soil health, the biomass or metabolic activity of species are more useful measures of their abundance than numbers of individuals. Thus, understanding of soil health and ecosystem function requires, besides knowledge of species diversity within functional classes, assessment of the range of functions currently performed in the system and the abundances of organisms by which they are performed. We propose a diversity-weighted abundance product for comparison of the functional magnitude of different assemblages of like organisms.  相似文献   

2.
Disturbance–diversity relationships have long been studied in ecology with a unimodal relationship as the key prediction. Although this relationship has been widely contested, it is rarely tested for soil invertebrate fauna, an important component of terrestrial biodiversity. We tested disturbance–diversity relationships for soil meso- and macrofauna in a salt marsh where periodic sea water inundation and cattle grazing occur as stressors. We hypothesized a unimodal inundation frequency–diversity relationship, whereas we expected grazing to overrule the effects of inundation frequency due to its large effects on the habitat of soil fauna. We found a negative relationship between inundation frequency and diversity at the ungrazed sites and no relationship at the grazed sites. Moreover, we found a negative relationship between community biomass and diversity for soil fauna that may have caused this negative disturbance–diversity relationship. Community biomass at the intermediate inundation frequency increased due to the dominance of Orchestia gammarellus (a macro-detritivore species), which could exploit low quality litters at the ungrazed sites. We highlight that the negative relationship between faunal community biomass and faunal diversity may influence disturbance–diversity relationships and illustrate that total biomass distribution of feeding guilds of soil fauna can improve our understanding of the soil fauna response to stressors in salt marshes.  相似文献   

3.
Edaphic fauna contributes to important ecosystem functions in grassland soils such as decomposition and nutrient mineralization. Since this functional role is likely to be altered by global change and associated shifts in plant communities, a thorough understanding of large scale drivers on below-ground processes independent of regional differences in soil type or climate is essential. We investigated the relationship between abiotic (soil properties, management practices) and biotic (plant functional group composition, vegetation characteristics, soil fauna abundance) predictors and feeding activity of soil fauna after accounting for sample year and study region. Our study was carried out over a period of two consecutive years in 92 agricultural grasslands in three regions of Germany, spanning a latitudinal gradient of more than 500 km. A structural equation model suggests that feeding activity of soil fauna as measured by the bait-lamina test was positively related to legume and grass species richness in both years. Most probably, a diverse vegetation promotes feeding activity of soil fauna via alterations of both microclimate and resource availability. Feeding activity of soil fauna also increased with earthworm biomass via a pathway over Collembola abundance. The effect of earthworms on the feeding activity in soil may be attributed to their important role as ecosystem engineers. As no additional effects of agricultural management such as fertilization, livestock density or number of cuts on bait consumption were observed, our results suggest that the positive effect of legume and grass species richness on the feeding activity in soil fauna is a general one that will not be overruled by regional differences in management or environmental conditions. We thus suggest that agri-environment schemes aiming at the protection of belowground activity and associated ecosystem functions in temperate grasslands may generally focus on maintaining plant diversity, especially with regard to the potential effects of climate change on future vegetation structure.  相似文献   

4.
More than 50 parameters of vegetation, soil and soil fauna were studied in 27 non-reclaimed post mining sites of various age (1–41 years old) located near the town of Sokolov (Czech Republic). A clay alkaline substrate (pH 8.5) was dumped in heaps; its pH and contents of available calcium and sodium decreased during succession. Total carbon and nitrogen, available potassium and water-soluble phosphorus increased with increasing successional age. In early stages, i.e. before the establishment of a shrub layer, the topsoil was formed mainly from the dumped spoil material. In shrub-dominated sites (14–22 years old), the litter reserve on the soil surface was higher than annual litter production, and a thick fermentation layer developed below the litter layer indicating slow litter decomposition and soil mixing. In older plots (24 year old or older), a humus layer was formed and the thickness of the fermentation layer decreased. Microstructure analysis indicated that earthworm activity, namely the mixing of organic and mineral layers, played a principal role in humus layer formation. No group of soil fauna preferred early successional stages, but tardigrades, bacteriophagous and fungivorous nematodes, and microsaprophagous dipterans, were tolerant to these stages. The density of most fauna guilds increased in intermediate stages with thick fermentation layer. Pauropods and testate amoebae reached highest densities on these sites. Macrosaprophagous guilds of soil fauna, most important for litter decomposition and soil mixing, attained their highest density in the oldest sites. Two clearly separated clusters of sites were distinguished based on TWINSPAN classification of vegetation. The first cluster included sites 1–23 years old, dominated by ruderal plants. Sites 24–41 years old were grouped in the second cluster; forest and grassland species were more frequent here. The presence of humus layer was selected by a discriminant analysis as the strongest predictor to discriminate between these two clusters. All considered ecosystem components, i.e. soil, soil fauna, and vegetation, passed through substantial changes in about the 25th year of succession and their changes were mutually correlated.  相似文献   

5.
Soil nematode communities in the 0–15 cm soil layer are used as indicators for describing the processes of fallow succession in the semi-arid zone of West Africa (Senegal). Abundance of plant feeding nematodes, non-plant feeding nematodes, plant parasite index (PPI), species richness and Shannon evenness of plant parasitic nematodes were measured at five stages of succession: fields, early (1–3 years), intermediate (8–10 years), old (18–20 years) fallows, and forest stage. These nematological indexes were analyzed simultaneously by multivariate analysis to show the indicative properties of nematode communities. Overall, changes in abundance of nematode groups, PPI and diversity, show continuous trends from early fallow to mature stages of the succession; these trends parallel theoretical trends in secondary succession. In addition, soil nematode parameters were meaningful and expressed interactions of various uncontrolled factors with successional processes, such as environmental conditions or cropping history. During the 3 years of the survey, the structure of nematode communities, described by index analysis, showed little temporal change and supported the use of nematodes as stable indicators.  相似文献   

6.
科尔沁沙地黑沙蒿人工植被土壤线虫群落特征   总被引:1,自引:0,他引:1  
管萍  刘艳军  张晓珂 《土壤通报》2007,38(2):314-317
本文针对科尔沁沙地黑沙蒿人工植被土壤线虫的总数、群落组成、营养类群进行了研究。结果表明,随着黑沙蒿种植年限的增加,土壤线虫数量显著增加。不同年限黑沙蒿植被之间土壤线虫总数差异显著(P<0.01)。在本研究中共获得线虫13科19属,其中Acrobeles为优势属。在半流动沙丘生态系统中,植物寄生线虫为优势营养类群;而在黑沙蒿人工植被生态系统中,线虫群落逐渐向以食细菌线虫占优势的方向演替。本实验结果表明,土壤线虫群落结构对退化沙漠生态系统的恢复阶段具有很好的生物指示作用。  相似文献   

7.
《Applied soil ecology》2000,14(1):27-36
The nematode communities of 36 grassland ecosystems in Romania, belonging to different plant associations and soil types, were studied. The abundance of nematodes, the species and trophic types present, as well as their distribution in relation to plant community and soil characteristics are analyzed and discussed.The abundance of nematodes from the 36 grasslands studied ranged between 0.41 × 106 and 8.57 × 106 individuals/m2, and a total of 121 genera and 145 species of nematodes were found. The highest diversity was found in grasslands developed on brown earth soil (65–67 genera and 74–76 species), with least diversity in those evolving on podzol and lithosol (33–36 genera with 25–28 identified species). Most of the dominant taxa were found in specific soil layers; some obligate plant parasitic genera (e.g., Paratylenchus, Rotylenchus, Criconema) showed preference for deeper soil layers. The nematode diversity index (H′), with values ranging between 2.38 and 3.47, did not differ significantly between the different types of grasslands. Plant feeding, bacterial feeding, hyphal feeding and omnivorous nematodes were the main groups in mountainous grasslands developed on different soil types. Plant feeding and bacterial feeding nematodes dominated the trophic structure and more plant feeders (62–69%) were found in communities of subalpine and alpine grasslands developed on podzol and alpine meadow soil, than in those developed on rendzina and lithosol (27–33%). The ratio of hyphal feeding to bacterial feeding nematodes (Hf/Bf) is constantly in favour of the bacterial feeding group, the values being an indicator of good soil fertility for most studied grasslands. The nematode communities of grasslands are grouped into six main clusters according to their genera affinity and distinguished by different grassland and soil types. Communities from subalpine grasslands developed on rendzina, acid brown and lithosol have the greatest similarities. An ordination of nematode communities in relation to important environmental variables is presented. Environmental variables relevant in explaining the patterns of nematode composition in grasslands, using canonical correspondence analysis (CCA), are: humus, pH, total nitrogen, exchangeable bases and soil type. No single factor could be selected.  相似文献   

8.
Nematodes as soil indicators: functional and biodiversity aspects   总被引:23,自引:0,他引:23  
Since it has become appreciated that soil nematode assemblages are abundant, diverse and contribute to soil nutrient turnover, they have been increasingly used as indicators of soil condition. Use of nematodes as functional indicators relies on the allocation of nematodes to feeding groups and reproductive strategies; in both cases groupings are uncertain. Species within feeding groups vary in their food resources and response to environmental variables, as shown by the difficulties in managing plant-pathogenic nematodes. Therefore species-level discrimination is necessary to permit further advances in understanding the role of nematodes in soil processes and thus in ecosystem resilience. Analysis of published nematode lists shows that among the bacterial-feeding nematodes Cephalobidae are often the most abundant group in soils; Rhabditidae may increase following a resource pulse; in stressed, natural environments Plectidae may be important. To be comparable with other biota, nematode biodiversity assessment requires species-level identification. In many jurisdictions such identification will be difficult due to inadequate systematic knowledge of the nematode fauna.  相似文献   

9.
Samples from an old Scots pine forest at Ivantjärnsheden in the middle of Sweden were used to study predictability and patterns of variation of soil nematode communities. There were two annual sampling series (1974–75 and 1977–78) and one long-term series sampled in September ten times over a period of 25 years. The abundance and the composition of the fauna fluctuated rather considerably in both the annual and long-term series. In the annual series abundance and species composition varied in a way which can partly be explained by changes in temperature and moisture. Total nematode abundance was influenced by soil water contents as indicated by co-variations with precipitation. Although the variations in abundance and fauna composition were large no systematic changes could be detected during 25 years. The differences in faunal structure between the two annual series were greater than between the annual and the long-term series.In all series there was a distinct vertical stratification of the fauna. In the superficial moss and litter layers species belonging to Adenophorea (Plectus) dominated. In deeper layers members of Rhabditida (Acrobeloides) contributed a greater proportion of the fauna. Variations of the annual series indicate that coexistence of different nematode species is facilitated by differences in response to temperature and moisture. The abundance of fungal and bacterial feeders changed in a regular way. During the summer the proportions of fungal and bacterial feeders were almost equal, but during the wet and cold winter the proportion of bacterial feeders increased. Rapidly growing bacterial feeding species belonging to Rhabditida were common in late summer and early autumn, whereas the more slowly growing bacterial feeders belonging to Adenophorea were most abundant during the winter. Although the community fluctuated rather much the average values indicated a rather high degree of predictability and also a high similarity with nematode faunas of other pine forest soils.  相似文献   

10.
A mesocosm experiment was conducted to investigate whether communities of arbuscular mycorrhizal (AM) fungi associated with roots of native (Piptatherum miliaceum, Retama sphaerocarpa, Psoralea bituminosa, Coronilla juncea, and Anthyllis cytisoides) and for comparison (Lolium perenne) seedlings in a heavy-metal-contaminated, semiarid soil were affected by the application of composted sugar beet waste. We also investigated whether there were relation between AMF diversity and metal concentration (Al, Cd, Cu, Fe, Mn, Pb and Zn) and total P in shoot as well as some soil parameters (total organic carbon and total N) when the SB waste was added to the soil. We analyzed a portion of approximately 795 base pairs of the small-subunit (SSU) rRNA gene by nested PCR, cloning, sequencing, and phylogenetic analyses. Twelve different AMF sequence types were distinguished: seven of these belonged to Glomus group A, one to Glomus group B, one to Diversispora, one to Archaeospora, and two to Paraglomus. The AM fungal populations colonizing roots in a heavy-metal-polluted soil were quite dependent on the host plant, the highest diversity values being obtained in authochtonous plants recognized as metallophytes, such as P. bituminosa, and in an allochtonous, invasive species (L. perenne). No significant correlation was found between AMF diversity and plant metal concentration and soil parameters. Excepting P. bituminosa, when sugar beet waste was added to soil, the populations of AM fungi in roots increased and the shoot metal concentrations decreased in all host plant species studied. Therefore, the addition of sugar beet waste can be considered a good strategy for the remediation and/or phytostabilization of mine tailing sites.  相似文献   

11.
土壤动物是湿地生态系统的重要组成部分,对湿地营养物质循环具有重要的作用。2013年10月至2015年7月,对甘肃太统-崆峒山国家级自然保护区16个湿地斑块的土壤无脊椎动物群落特征进行了研究,共获得土壤无脊椎动物7门130类185 033只。节肢动物门(Arthropoda)和线虫动物门(Nemata)为优势类群,分别占总捕获量的47.50%和26.08%;环节动物门和轮虫动物门为常见类群,分别占总捕获量的14.95%和9.26%;扁形动物门、软体动物门和缓步动物门为罕见类群,分别占总捕获量的1.25%、0.66%和0.30%。节肢动物门和线虫动物门构成了土壤动物的主体,对土壤动物群落特征起着决定性作用。16个湿地斑块中,2#样地的土壤动物个体数量最多;7#样地的类群数量最多,Shannon-Wiener物种多样性指数(4.496 7)最高;14#样地土壤动物个体数量和类群数量都最少。各样点土壤动物间的相似性指数在0.594 6~1之间,表明16个湿地斑块的土壤动物群落多样性为中等不相似到中等相似,这反映了甘肃太统-崆峒山国家级自然保护区的16个湿地斑块保护状况良好,受外来影响较少;同时也反映了不同斑块之间的差异性,这些差异性与人类活动干扰有关。  相似文献   

12.
The abundance and functional structure of soil micro- (nematodes) and mesofauna (collembolans and mites) in relation to species diversity and initial C:N ratio of plant litter were studied in a field mesocosm experiment. A total of five litter treatments were applied to generate an increasing diversity of plant species (one, three and 12 species) and/or differences in initial C:N ratio of the litter (low, intermediate and high ratio). Samples were taken 3, 6 and 24 months after the litter exposure. On each sampling date litter and underlying sand samples were taken. Our results showed that litter quality, but not litter diversity was the factor which affected the three animal groups under study. The effect of litter was dependent on the time of litter exposure. Nematode fauna colonized litter earlier than the two mesofaunal groups. Nematodes responded apparently to litter quality gradient at early stages of litter decomposition. Three months after the start of the experiment the highest density of nematodes was noticed in single species litter of Trifolium pratense. Bacterial-feeding nematodes dominated in all litter treatments; on the first sampling date their percent share in Trifolium litter reached even 99.9%. Opposite to nematodes at late stages of litter decomposition the two mesofaunal groups seemed to show some preferences for low quality litter of Festuca rubra. Collembolan and nematode diversity was affected in similar way by the litter quality; the lowest diversity of the animal communities was found in the litter of the lowest initial C:N ratio. Maturity index of nematode communities was found to be a good index to differentiate between litters of different quality. The abundance and community structure of the three animal groups in underlying sandy soil was not significantly influenced by experimental conditions.  相似文献   

13.
We report here on an 8-year study examining links between plant and nematode communities in a grassland plant diversity experiment, located in the north of Sweden on previous agricultural soil. The examined plots contained 1, 4 and 12 common grassland plant species from three functional groups; grasses, legumes and forbs. The same plant species composition was maintained in the plots through weeding and resowing during the experimental period. The hypotheses were (i) that the nematode community would shift towards a more diverse and mature fauna over time and (ii) that the effects of both plant species identity and plant species richness would increase over time. As hypothesized, the Bongers’ Maturity Index (a measure of nematode responses to disturbance) increased over time, but not nematode diversity. Instead, the nematode community development in the present grassland experiment seemed to be more characterized by shifts in dominance patterns than by colonization of new taxa. Clear temporal trends were found for plant-feeders and Adenophorea bacterial-feeders which increased in abundance over time in almost all plant treatments. Rhabditidae bacterial-feeders decreased in abundance over time, in particular in plots with legumes. Fungal-feeders, omnivores/predators and the two nematode indices PPI (Bongers’ Plant Parasitic Index) and NCR (Nematode Channel Ratio) had significant interactions between plant composition and time giving some support to our second hypothesis. Our results highlight the need for long-term experiments to examine plant species effects on soil fauna, especially on taxa belonging to higher trophic levels. The results also stress the importance of plant composition for belowground soil faunal communities.  相似文献   

14.
海拔对表居土壤动物不同取食功能群多度分布的影响   总被引:1,自引:0,他引:1  
物种多度分布格局是群落生态学研究的前沿领域之一。海拔梯度下开展土壤动物多度分布研究有利于认识分解者群落的构建过程如何响应环境变化。选用5种常见的生态位分配模型(断棍模型、生态位优先占领模型、生态位重叠模型、随机分配模型和优势优先模型),分别采用个体数量与生物量作为多度表征指标,对分布于北京东灵山辽东栎林下不同海拔范围的表居土壤动物群落整体与不同取食功能群(杂食者、植食者、捕食者、腐食者)的相对多度分布进行研究。结果表明,拟合表居土壤动物群落整体的最优生态位分配模型不受海拔影响,均为断棍模型。但表居土壤动物各功能群多度分布受海拔影响,杂食者随海拔升高,最优模型由断棍模型转变为生态位优先占领模型,而植食者与之相反。多度表征指标选择影响拟合表居土壤动物不同功能群(捕食者和腐食者)多度分布的最优模型。总体而言,海拔和多度指标选择并未影响表居土壤动物整体的多度分布,但对表居土壤动物中不同取食功能群的多度分布有影响。  相似文献   

15.
Atmospheric S and N compounds accumulate in the surface layers of the forest soil environment, where they affect soil biota and nutrient availability for tree growth. In addition to measures to reduce the input of atmospheric deposition, removal of the ectorganic layers by sod-cutting may contribute to the recovery of the soil ecosystem. In this study, we examined the effects of sod-cutting on the nematode fauna of a Scots pine forest, 1 and 3 years after treatment. Sod-cutting reduced the total numbers of nematodes, nematode taxa, and Maturity Index. The first taxa that colonized the newly developing organic layers after sod-cutting had low colonizer-persister (c-p) values, and appeared to have originated from the tree canopy and mineral soil. Colonization, presumably from nearby untreated plots, was observed 3 years after the sod-cutting. The initial (after 1 year) nematode community of the new organic layer comprised hyphal-, bacterial-, and algal-feeding nematodes, whereas plant-feeders, predators, and omnivores were not detected. The composition of the nematode fauna in the ectorganic layers 15 and 39 months after sod-cutting was highly similar to that of the nematode fauna of the early stages of a primary succession of Scots pine forest in a reference area in the Netherlands. In the mineral soil only insect parasites were negatively affected by sod-cutting.  相似文献   

16.
Recovery of soil organic matter, organic matter turnover and mineral nutrient cycling is critical to the success of rehabilitation schemes following major ecosystem disturbance. We investigated successional changes in soil nutrient contents, microbial biomass and activity, C utilisation efficiency and N cycling dynamics in a chronosequence of seven ages (between 0 and 26 years old) of jarrah (Eucalyptus marginata) forest rehabilitation that had been previously mined for bauxite. Recovery was assessed by comparison of rehabilitation soils to non-mined jarrah forest references sites. Mining operations resulted in significant losses of soil total C and N, microbial biomass C and microbial quotients. Organic matter quantity recovered within the rehabilitation chronosequence soils to a level comparable to that of non-mined forest soil. Recovery of soil N was faster than soil C and recovery of microbial and soluble organic C and N fractions was faster than total soil C and N. The recovery of soil organic matter and changes to soil pH displayed distinct spatial heterogeneity due to the surface micro-topography (mounds and furrows) created by contour ripping of rehabilitation sites. Decreases in the metabolic quotient with rehabilitation age conformed to conceptual models of ecosystem energetics during succession but may have been more indicative of decreasing C availability than increased metabolic efficiency. Net ammonification and nitrification rates suggested that the low organic C environment in mound soils may favour autotrophic nitrifier populations, but the production of nitrate (NO3?) was limited by the low gross N ammonification rates (≤1 μg N g?1 d?1). Gross N transformation rates in furrow soils suggested that the capacity to immobilise N was closely coupled to the capacity to mineralise N, suggesting NO3? accumulation in situ is unlikely. The C:N ratio of the older rehabilitation soils was significantly lower than that of the non-mined forest soils. However, variation in ammonification rates was best explained by C and N quantity rather than C:N ratios of whole soil or soluble organic matter fractions. We conclude that the rehabilitated ecosystems are developing a conservative N cycle as displayed by non-mined jarrah forests. However, further investigation into the control of nitrification dynamics, particularly in the event of further ecosystem disturbance, is warranted.  相似文献   

17.
18.
中国小麦田土壤线虫对生物炭添加的响应   总被引:1,自引:0,他引:1  
While studies have focused on the use of biochar as soil amendment, little attention has been paid to its effect on soil fauna. The biochar was produced from slow pyrolysis of wheat straw in the present study. Four treatments, no addition (CK) and three rates of biochar addition at 2 400 (B1), 12 000 (B5) and 48 000 kg ha-1 (B20), were investigated to assess the effect of biochar addition to soil on nematode abundance and diversity in a microcosm trial in China. The B5 and B20 application significantly increased the total organic carbon and the C/N ratio. No significant difference in total nematode abundance was found among the treatments. The biochar addition to the soil significantly increased the abundance of fungivores, and decreased that of plant parasites. The diversity of soil nematodes was significantly increased by B1 compared to CK. Nematode trophic groups were more effectively indicative to biochar addition than total abundance.  相似文献   

19.
Understanding how environmental factors structure communities is important in conservation biology and ecosystem management. The aim of this study was to test the hypothesis that a plant-feeding nematode community composed of six species is structured by soil type and climate at the landscape scale, and that niche partitioning via these factors is consistent with the coexistence of the species. Martinique has an impressive diversity of abiotic factors (climate and soil type) over a relatively small land area, which facilitates the study of how soil type and climate affect the nematode community.We conducted this study by building an extensive data set containing the abundance of each nematode species on banana (3708 samples and 5,673,705 nematodes) in a wide range of sites in Martinique. The data set also contained environmental data (soil, climate) and plantation age. We analyzed the response of each nematode species to climate and soil type with a generalized linear model in order to understand whether niche partitioning of factors could contribute to the coexistence of the nematode species.Temperature, rainfall, soil type, and plantation age significantly affected the abundance of the six nematode species. While some pairs of species shared the same environmental niches, other showed clear niche partitioning along climatic axes. The two dominant species, Radopholus similis and Helicotylenchus multicinctus, have similar convergent ecological niches regarding climate, soil type, plantation age, and host range. These two species, which often co-occur, probably have different resources at the root scale. Soil type and climate structure plant-feeding nematode species community at the island scale. Further studies need to evaluate coexistence at the root scale among dominant species.  相似文献   

20.
严珺  吴纪华 《土壤》2018,50(2):231-238
生物多样性与生态系统功能一直是生态学研究的一个热点。近些年来的研究表明,植物多样性除了影响陆地生态系统地上部分的初级生产力等生态系统功能,还会间接影响地下生物多样性及土壤生态系统过程。本文概述了植物多样性对土壤动物的影响及其主要机制,归纳了植物多样性通过改变输入土壤中的资源数量与资源多样性、微生境结构、土壤环境因子等影响土壤动物的途径。目前关于土壤动物群落对植物多样性的响应仍存在很多问题和争议,本文总结了需要进一步深入研究的方向,特别指出了要加强研究影响植物多样性与土壤动物关系的生物与非生物因子、后续的生态效应和反馈、不同机制和途径的贡献定量化等。  相似文献   

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