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1.
R. J. Hobbs 《Plant Ecology》1984,57(2-3):129-136
Studies on a long-term experiment on Calluna-Eriophorum bog indicate that the length of time between management fires affects the post-fire development. A short rotation (every 10 years) results in increased dominance by Eriophorum spp. while a long rotation (every 20 years) results in greater abundance of Calluna vulgaris after fire. Variations in post-fires species abundances are related to pre-fire stand composition coupled with the patchy distribution of regeneration centers of rhizomatous species. The usefulness of burning this vegetation type in management for herbivore grazing is questioned.Nomenclature follows Tutin et al. (1964 80) for vascular plants. Smith (1978) for mosses, Watson (1981) for liverworts and Hawksworth, James & Coppins (1980) for lichens. Following common practice. Calluna vulgaris is referred to simply as Calluna. Acknowledgements. I thank M. Raves and the Nature Conservancy Council for permission to work on Moor House National Nature Reserve and for the use of data from Reserve Records, V. J. Hobbs for field assistance, and Prof. C. H. Gimingham for help and advice during the study. I also thank all who worked at Moor House for creating a pleasant working environment. The long-term experiment was planned by Dr R. J. Elliot and analyzed initially by Dr G. I. Forrest.  相似文献   

2.
A study is made of the dune system at Tentsmuir Point National Nature Reserve, Scotland, using transects crossing the vegetation zonation. Principal Components Analysis and tabular ordination are used to analyse the data, and an attempt is made to relate the results obtained to the dynamics of the system. The effects of different management regimes are considered, and it is concluded that the establishment of pine on the area has the largest effect on the development of the vegetation. Reduction in grazing pressure by rabbits is found to increase species diversity slightly, but has no major influence as yet on vegetation development. While some information on the dynamics of the vegetation can be inferred, the problems involved in this are considered to be large, and the study raises a number of questions to be studied in greater detail. It is concluded that permanent plots would be the most effective method to employ.Nomenclature follows Clapham, Tutin & Warburg (1962) for vascular plants, Watson (1968) for bryophytes, and Duncan (1970) for lichens.We should like to thank Dr. R. A. H. Smith of the Nature Conservancy Council for her assistance and permission to work on Tentsmuir Point N. N. R., and Mr. J. G. Young, then warden at Tentsmuir for his help at the start of the project. We are grateful to Dr. R. Meutzelfeldt for computational advice. In addition, one of us (R.J.H.) would like to thank Dr. E. van der Maarel and Dr. R. S. Clymo for their tuition during the Nordic Council for Ecology course Numerical Methods in Vegetation Analysis' in Lund, September, 1979.  相似文献   

3.
Question: Can long‐term grazing management maintain and restore species‐rich sand dune plant communities within a sand dune site of high conservation interest? Location: Newborough Warren, North Wales, UK. Methods: Vegetation changes that occurred between 1987 and 2003, subsequent to grazing by domestic livestock being introduced to the site after decades with little or no stock grazing, were analysed using data collected from permanent monitoring quadrats over a 16‐year period. Results: At the plant community level, grazing brought about a shift from a tall‐grass dominated, species‐poor community to a more species‐rich community in the dry dunes, but did not change community type in dune slacks. However, at the species level, grazing enhanced the abundance of some desired perennial, annual and biennial species, graminoids and bryophytes in both habitat types. The increased frequency of positive indicator species for habitat condition suggests that grazing was beneficial for species of conservation interest. Ellenberg nitrogen (N) values decreased after grazing in dry habitats but showed no long‐term change independent of grazing, suggesting no increase in site fertility over the study period. Surprisingly, light (L) values also decreased in the dry dunes after grazing. Conclusions: Long‐term grazing management can play an important role for the conservation of dune communities and associated species. Because of its positive effects on species diversity, plant communities and habitat condition in sand dunes, livestock grazing is recommended for conservation management.  相似文献   

4.
Questions: What is the best grassland management regime for the threatened plant species Gladiolus imbricatus; is the stage structure of local populations a feasible indicator of the effect of changed management. Location: Coastal meadow system in southwestern Estonia. Methods : The effect of five management regimes was studied in a long‐term (three‐year) field experiment: (1) mowing in late July, (2) grazing by cattle, (3) grazing by sheep, (4) sheep grazing during the first year and mowing during subsequent years, (5) no management (control). Results: The population density increased significantly in response to the mowing treatment and to the mowing after sheep grazing treatment. The proportion of grazed plant individuals was higher in the sheep‐grazed than in the cattle‐grazed treatment. Generative and vegetative adult individuals of G. imbricatus were significantly more damaged by cattle herbivory than juveniles. All management regimes shifted the population structure towards a dynamic state where juvenile stages dominate, while the not managed control retained a regressive population structure. Conclusions: Population stage structure was a useful indicator of different management conditions, even in the case where population density did not differ. As indicated by population stage structure, the best management regime for G. imbricatus was either mowing in late July only, or alternation of grazing and mowing in different years.  相似文献   

5.
S. Biswas 《Hydrobiologia》1964,23(3-4):511-514
Summary A new taxon, Nitzschia sinuata, var. denticuloides, var. n. was found to occur sparingly in two freshwater springs of Newborough Warren, Anglesey, North Wales, Great Britain. These two springs were characterized by shallow waters, moderate temperature and high pH. Dysharmonious or idiotrophic nature of the water was evident from high calcium, sodium and chloride contents, as well as low phosphate and potassium contents. The algal community was found to be dominated by Cladophora fracta (Dillw.) Kuetz. bearing a vast population of epiphytic diatoms such as Epithemia and Achnanthes species.
Zusammenfassung Eine neue Kieselalge, Nitzschia sinuata, var. denticuloides, var. n., ist in zwei Süsswasserquellen in Newborough Warren, Anglesey, Nord Wales, Grossbritannien spärlich verbreitet entdeckt worden. Diese beiden Quellen sind durch seichtes Wasser, milde Temperaturen und hohen pH Wert gekennzeichnet. Hohe Kalcium, Sodium und Chlorid Werte und niedrige Phosphat und Kalium Werte beweisen den dysharmonischen oder idiotrophen Charakter des Wassers. Die Algengesellschaft bestand hauptsächlich aus Cladophora fracta (Dillw.) Kuetz., dicht besetzt von epiphytischen Diatomeen wie Epithemia and Achnanthes Arten.
  相似文献   

6.
通过野外调查和资料整理,统计分析梅花山自然保护区蕨类植物区系组成和分布区类型,比较其与周边相邻4个自然保护区的蕨类植物区系的相似性。结果表明:(1)梅花山自然保护区共有蕨类植物42科83属189种,科、属组成优势现象明显,区系起源古老。(2)分布区类型在科、属级水平上以泛热带分布和世界分布为主,种级水平以热带亚洲分布、东亚分布和中国特有分布为主,热带亲缘明显,具有由热带向温带过渡的性质。(3)在地理亲缘关系上,梅花山与梁野山的蕨类植物区系联系最为紧密,与圭龙山的关系次之,与热带区系性质较强的南靖南亚热带雨林自然保护区和典型的中亚热带性质的武夷山自然保护区的种子植物区系联系较为疏远,具有从南亚热带向中亚热带过渡的明显特点。  相似文献   

7.
During the last decades chalk grasslands lost their agricultural importance in the greater part of their distribution area in W Europe. Due to their botanical richness a number of chalk grassland sites were established as Nature Reserve. As a consequence of the semi-natural character of these grasslands an appropriate management is necessary to maintain or to re-create this vegetation including a great number of rare and endangered species.This paper deals with the results of three different management practices, viz. mowing in autumn, sheep grazing and abandoning, of a medium term (8–11 yr) permanent plot experiment. Sheep grazing was considered the best management since it resulted in the highest number of species, phanerogams as well as bryophytes, and the highest number of characteristic chalk grassland species. Abandoning resulted in a decrease in species number and a dominance of a few species only.The changes in species number are related to the above ground biomass. Under the canopy in the abandoned plot light intensity and the Red/Far-red ratio are very low, which partly explains the decrease in species number as such conditions are not favourable to seedling emergence and survival.Plant nomenclature follows Heukels & Van Ooststroom (1975) for phanerogams, Margadant & During (1976) and van der Wijk et al. (1969) for bryophytes, and Westhoff & den Held (1969) for syntaxa.Presented at the Symposium on Vegetation Dynamics, organized by the International Society for Vegetation Science at Montpellier, 15–20 September 1980. I am grateful to Dr. H. J. During for useful comments.  相似文献   

8.
该研究在野外调查、搜集文献和整理植物数据库的基础上,对广东南雄丹霞梧桐自然保护区蕨类植物区系组成和分布区类型进行统计分析,并比较与周边相邻3个研究区蕨类植物区系的相似性,为研究区植物资源的合理开发利用提供依据。结果表明:(1)广东南雄丹霞梧桐自然保护区共统计到蕨类植物28科51属84种,科属结构单一,分化水平不高,以寡种科属居多,但区系起源古老,进化关系连贯。(2)该区蕨类区系地理联系广泛,在科、属水平上与热带亲缘程度较高,以泛热带分布、亚热带分布为主,在种水平上以热带亚洲分布和东亚分布为主,区系地理成分呈热带向温带过渡渗透性质。(3)在与邻近区亲缘关系上,与观音岽联系最为紧密,其次是冠豸山,与丹霞山的关系较疏远。该研究区与观音岽的属、种相似性系数均在0.83以上,区系同质性明显,与两者现代自然条件相似的事实相吻合。该研究结果为探讨丹霞地貌地带蕨类植物的起源和发育提供了重要依据。  相似文献   

9.
J. P. Bakker 《Plant Ecology》1985,62(1-3):391-398
Grazing an abandoned salt marsh causes retrogressive succession, since mid salt-marsh communities change into lower salt-marsh communities. Grazing and mowing are compared in detail. Both management practices enhance species diversity in an abandoned salt marsh. This can be attributed to the removal of litter. The finding that lower salt-marsh species appear more with grazing than with mowing or abandoning is not related to a higher soil salinity as compared to mowing or abandoning, but probably to locally baring of the soil by grazing animals. Only species of pioneer or unstable environments seem to have a persistent seed bank, for other species seed dispersal seems to be a limiting factor for their establishment.Nomenclature follows Heukels & van Ooststroom (1977) for species; Westhoff & den Held (1969) for syntaxa.Mrs R. Rusthoven analyzed the soil samples, Mr E. Leeuwinga drawed the figures, and Mrs J. O'Brien corrected the English text.  相似文献   

10.
Summary Part of a salt-marsh (32 ha), ungrazed from 1958 until 1971, was grazed again from 1972 onwards with young cattle (1.3–1.7 per ha, May–October). In five vegetation types management experiments, including doing nothing (control). June mowing, August mowing, June and August mowing, all in combination or not in combination with grazing have been started with the objective to compare annually their effects on the vegetational structure and composition by means of permanent plots (2×2 m).Thirteen years (1958–1971) after the grazing had ceased the vegetation types of Festuca rubra/Armeria maritima, Artemisia maritima, Juncus maritimus and Elytrigia pungens hardly changed anymore. The vegetation type of Festuca rubra/Limonium vulgare, changed considerably. The experiments showed rather specific effects during the period 1971–1975 for each type of vegetation. Changes in the Festuca rubra/Armeria maritima vegetation were small and gradually under all treatments. Changes in The Artemisia maritima, Festuca rubra/Limonium vulgare and Juncus maritimus vegetation types were rather great under the different grazing treatments, the changes being abrupt and especially taking place in the third and fourth year of the experiments. The Elytrigia pungens vegetation showed large changes under all treatments, except the control plot, whereas these changes were abrupt, particularly occurring in the first and second year of the experiments. The study is continued.Nomenclature of taxa follows Heukels & van Ooststroom (1970), that of syntaxa Westhoff & den Held (1969).Contribution to the Symposium of the Working Group for Succession research on permanent plots of the International Society for Vegetation Science, held at Yerseke, the Netherlands, October 1975.Thanks are due to Prof. Dr. D. Bakker for his interest in the present study and his critical reading of the text, and to Drs D.C.P. Thalen for critical reading and correction of the English text. Thanks are also due to the students who analyzed the permanent plots: M. van der Duim and F. Prins (1971), M. van der Duim (1972), R. Schwab and T. Schwab-Vos (1973), and G. Allersma (1974, 1975).  相似文献   

11.
In a permanent plot experiment started in 1971, the effects of several management regimes on diversity of a Dutch chalk grassland have been investigated and the results have been compared to existing models predicting general trends in diversity. Treatments included grazing, mowing, and leaving untouched; in the mown plots, the effects of fertilizing and sod cutting were also studied. Grazing resulted in the highest diversity, leaving untouched in the lowest (ca. 42 and 15 spp. per m2, respectively). Within the mown plots, fertilizing decreased diversity. The effects of sod cutting disappeared after some years. The results conform best with the response surface model of Huston (1979) relating diversity to frequency of population reduction and rate of competitive displacement, but a slight modification of the shape of the surface is suggested.Nomenclature follows van der Meijden et al., 1983.The authors are very grateful to Dr J. Miles (Banchory, U.K.) for stimulating remarks and to Prof. Dr. M. J. A. Werger, Dr R. K. Peet and two reviewers for many valuable comments and suggestions.  相似文献   

12.
通过野外调查、采集标本和查阅相关文献资料,编制福建梁野山自然保护区野生种子植物名录,进行植物区系组成和分布区类型的分析,并将其与周边相邻2个保护区的植物区系进行比较。结果表明:(1)梁野山自然保护区共有野生种子植物154科662属1 498种,种类丰富。(2)区系地理成分以热带分布型为主,其中在科级水平上热带分布型所属科共有85科,占总科数的69.67%;在属级水平上热带性质分布型的属有371属,占总属数的60.82%。但相当数量温带成分的存在,体现了亚热带植物区系的特点。(3)对梁野山保护区与周边相邻的武夷山和南靖南亚热带雨林保护区的植物区系比较发现,梁野山种子植物区系属数的热带属数/温带属数(R/T值,1.66)高于武夷山的R/T值(1.10)而低于南靖南亚热带雨林保护区的R/T值(2.68),梁野山种子植物区系与该相邻2个保护区的相似性系数非常接近,但在区系成分上,梁野山既有与武夷山共有而南靖南亚热带雨林保护区没有分布的温带成分,也有与南靖南亚热带雨林保护区共有而武夷山没有的热带成分,说明梁野山植物区系与其地处武夷山脉南端的地理位置相一致,具有明显的从南亚热带向中亚热带过渡的特点。  相似文献   

13.
Abstract. Vegetation changes in a semi‐natural grassland of wooded meadow type that had been grazed for centuries are described following the introduction of various management regimes: mowing each year, mowing every third year, burning, mechanical removal of woody plants, chemical treatment of woody plants, continuous grazing and abandonment. The experiment was established in southern Sweden in 1972 and has been in progress for 15 years. In 1972, 1980 and 1986 the botanical composition in these plots was investigated in permanent subplots. The study clearly demonstrates that mowing or grazing is necessary to preserve community structure and that mowing is to be preferred in cases where maintaining species richness is of primary concern. Mowing every third year delayed vegetation change and prevented woody species from spreading. Therefore, periodic mowing might be an alternative way to preserve the flora. In contrast, yearly burning does not seem to be a viable management in this type of semi‐natural grassland. To preserve the open landscape regeneration of woody plants has to be prevented. However, in plots where woody plants were removed the typical grassland flora declined. Abandonment resulted in closed forest.  相似文献   

14.
In grassland reserves, managed disturbance is often necessary to maintain plant species diversity. We carried out experiments to determine the impact of fire, kangaroo grazing, mowing and disc ploughing on grassland species richness and composition in a nature reserve in semi‐arid eastern Australia. Vegetation response was influenced by winter–spring drought after establishment of the experiments, but moderate rainfall followed in late summer–autumn. Species composition varied greatly between sampling times, and the variability due to rainfall differences between seasons and years was greater than the effects of fire, kangaroo grazing, mowing or disc ploughing. In the fire experiment, species richness and composition recovered more rapidly after spring than autumn burning. Species richness and composition were similar to control sites within 12 months of burning and mowing, suggesting that removal of the dominant grass canopy is unnecessary to enhance plant diversity. Two fires (separated by 3 years) and post‐fire kangaroo grazing had only minor influence on species richness and composition. Even disc ploughing caused only a small reduction in native richness. The minor impact of ploughing was explained by the small areas that were ploughed, the once‐off nature of the treatment, and the high degree of natural movement and cracking in these shrink‐swell soils. Recovery of the composition and richness of these grasslands was rapid because of the high proportion of perennial species that resprout vegetatively after fire and mowing. There appears to be little conservation benefit from fire, mowing or ploughing ungrazed areas, as we could identify no native plant species dependent on frequent disturbance for persistence in this grassland community. However, the ability of the Astrebla‐ and Dichanthium‐dominated grasslands to recover quickly after disturbance, given favourable seasonal conditions, suggests that they are well adapted to natural disturbances (e.g. droughts, fire, flooding and native grazing).  相似文献   

15.
Glasshouse and mini-sward experiments were done to determine the relative roles of grazing and trampling by livestock in transmitting white clover mosaic (WC1MV) and subterranean clover mottle (SCMoV) viruses between clover plants in pastures. Wounding due to grazing was simulated by repeatedly cutting plants with serrated scissors (glasshouse) or mowing (mini-swards), while wounding due to trampling was simulated by repeatedly bashing plants with the flat end of a wooden hammer handle (glasshouse) or rolling (mini-swards). In glasshouse experiments, cutting was more effective than bashing in transmitting WC1MV to white clover (Trifolium repens) plants but cutting and bashing transmitted it to subterranean clover (T. subterraneum) plants at similar rates. In an experiment with white clover mini-swards, mowing was more effective than rolling in transmitting WC1MV, and when both were combined, initially spread exceeded that obtained when the spread from mowing and rolling alone was added together. In glasshouse experiments, bashing was more effective than cutting in transmitting SCMoV to subterranean clover plants. In one experiment, neither mowing nor rolling spread SCMoV in mini-swards of subterranean clover. When transmission to subterranean clover cultivars which were ‘susceptible’ or ‘moderately susceptible’ to SCMoV was compared in glasshouse experiments, repeated bashing spread the virus more slowly to the ‘moderately susceptible’ cultivars. When mixed with ruminant saliva, infective sap containing WC1MV or SCMoV was still infective to clover plants after 4 wk storage at room temperature. When infective sap was allowed to dry naturally on a metal surface, SCMoV still infected clover plants when the dried sap was taken up in tap water after 4 but not 14 days, while WC1MV was infective after 24 h but not 4 days. These results suggest that grazing and mowing are more effective than trampling at transmitting WC1MV to white clover plants in pastures, while trampling is more effective at spreading SCMoV to subterranean clover. However, both transmitted WC1MV to subterranean clover at similar rates. Possible reasons for these differences are discussed in relation to differences in clover plant morphology and virus-specific factors.  相似文献   

16.
陕西周至老县城自然保护区两栖动物多样性调查   总被引:6,自引:1,他引:5  
江建平  王斌  刘炯宇  谢锋 《四川动物》2006,25(2):281-284,F0004
于2003年7月~8月和2004年5月对陕西周至老县城自然保护区进行两次实地考察,结合有关文献资料的报道结果,该地区有两栖动物8种,归隶2目、5科、8属,其中1种为未定种Scutiger sp.,与宁陕齿突蟾Scutiger ningshanensis相似,其代表的属和科在邻近的5个自然保护区目前均无发现与报道;与邻近的5个自然保护区的物种分布相似性比较表明,老县城自然保护区在两栖动物分布上与周至自然保护区更相近.  相似文献   

17.
Livestock grazing occurs in many protected areas for wildlife and has become a threat to wildlife worldwide. Livestock grazing within protected areas causes negative effects to rare wildlife (e.g., giant panda [Ailuropoda melanoleuca]) and their habitat. We used the 2,000-km2 Wolong National Nature Reserve, Sichuan Province, southwestern China, to document the effects of livestock on the giant panda and its habitat. We monitored arrow bamboo (Bashania fangiana), wildlife sign (i.e., feces and tracks), and characteristics of plant communities in intact habitat (IH; limited livestock grazing) and disturbed habitat (DH; with grazing disturbance) to assess the effects of livestock grazing and the responses of giant pandas and sympatric species across spatial and temporal scales. Bamboo coverage and the height and basal diameter of bamboo in IH were greater than those in DH, whereas the number of herbaceous species and herbaceous coverage in IH were lower than those in DH. Wildlife signs in IH were greater than those in DH; specifically, giant panda and red panda (Ailurus fulgens) signs were greater, whereas signs of sambar (Rusa unicolor) and tufted deer (Elaphodus cephalophus) in IH were similar to those in DH. Livestock grazing reduced bamboo, which may threaten the long-term survival of the giant panda. Our results have implications for understanding and management of livestock grazing in the Wolong National Nature Reserve and elsewhere. © 2019 The Wildlife Society.  相似文献   

18.
The distribution of Lopinga achine (Lepidoptera Nymphalidae, Satyrinae) in the Czech Republic has declined from thirty grid squares before 1950 to just one extant population, restricted to a single area of deciduous woodland. A review of historical sites shows that this species used to occur in various types of deciduous woodland with a relatively sparse canopy maintained by coppicing and/or grazing. The extant population inhabits mature woodland with a mean canopy cover of 60% (quartiles 50% and 65%), sparse shrubs and a species-rich herb layer containing plant species requiring dry, warm and nutrient-poor conditions. The larval host plants are the fine-leafed sedges, Carex fritschii and C. michelii. In 2006, the total population contained about 10,000 adults but this may be an over-estimate, biased by male behaviour. Measurements of adult mobility, well approximated by an inverse-power function, suggested that all existing colonies are interconnected by dispersal. Continuing existence of the population depends on two conditions; nutrient-poor conditions for a diverse ground flora and a sparse tree canopy. While canopy closure is gradually increasing, the herb layer is threatened by soil enrichment due to the demise of traditional grazing, litter raking and grass mowing in woodlands. Any future management to favour Lopinga achine should include both measures to maintain a sparse canopy and measures to export biomass, such as raking or mowing of ground flora or, preferably, re-establishment of grazing. An erratum to this article can be found at  相似文献   

19.

Questions

Can hemiparasitic Rhinanthus major originating from a local population suppress the competitive clonal grass Calamagrostis epigejos and reverse its expansion in species‐rich semi‐natural grasslands? Does sowing seeds of R. major facilitate restoration of target meadow vegetation? Is R. major more beneficial for biodiversity restoration/conservation than increased mowing intensity, a conventional measure to suppress C. epigejos?

Location

?ertoryje National Nature Reserve, Bílé Karpaty (White Carpathians) Protected Landscape Area, Czech Republic.

Methods

We conducted a before‐after‐control‐impact experiment in meadow patches heavily infested by C. epigejos: eight blocks, each containing four plots with four treatment combinations: (1) traditional management, i.e. mowing once in summer, (2) mowing in summer and autumn (3) mowing in summer and seed sowing of R. major, (4) mowing in summer and autumn and seed sowing of R. major. Above‐ground biomass of C. epigejos and vegetation composition of each of the plots were monitored every year from 2013 to 2016. To assess the effects of treatments, we analysed biomass production of C. epigejos, herb layer cover and vegetation composition.

Results

Both sowing R. major and an additional autumn meadow cut significantly suppressed C. epigejos. Their effects were additive and of comparable size. Both treatments also had significant but markedly different effects on community composition. Rhinanthus major facilitated directional community composition change towards the regional Brachypodio‐Molinetum meadows. In contrast, increased mowing intensity significantly decreased frequency of threatened species, which however may have also been influenced by R. major.

Conclusions

Sowing of autochthonous R. major seeds was demonstrated as an efficient tool to suppress C. epigejos and facilitate community restoration. It can be combined with an additional meadow cut to further accelerate decline of the grass. The additional cut should however be used as a short‐term practice (1–2 years) only to minimize potential negative effects of its long‐term application on some threatened plant species. The effects of R. major are comparable to those of Rhinanthus alectorolophus reported previously. As a species occurring naturally in species‐rich dry grasslands, R. major has a broader and longer‐term application potential than R. alectorolophus in ecological restoration and conservation of these communities.  相似文献   

20.
广东郁南同乐大山自然保护区种子植物区系研究   总被引:2,自引:1,他引:1  
通过野外调查与查阅资料,广东郁南同乐大山自然保护区共有野牛种子植物149科542属1 002种.种子植物区系组成丰富,区系地理成分复杂,以南亚热带和热带北缘植物区系地理成分为主.区内珍稀濒危植物多,特有现象较明显,植物区系起源古老.与其它邻近地区植物区系相比较,同乐大山自然保护区种子植物区系与广西龙虎山自然保护区、广东黑石顶自然保护区的相似性较高,与湖南武陵源的相似性较低.  相似文献   

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