1,721,128 research outputs found
Ectomycorrhizal symbionts of silver fir (Abies alba Mill.)
Full text linkPoznavanje ektomikoriznih (ECM) simbiontov bele jelke do zdaj po večini temelji na morfološko-anatomskih opisih tipov ektomikorize ali pojavljanju trosnjakov. Ektomikoriza bele jelke v Sloveniji še ni bila ciljno raziskana. V okviru raziskave smo na treh klimatološko in pedološko različnih vzorčnih ploskvah v obdobju dveh let v rastnih sezonah enkrat mesečno vzorčili drobne korenine bele jelke in jih analizirali z morfološko-anatomsko metodo. Na podlagi opaženih morfološko-anatomskih lastnosti tipov ektomikorize smo ločili posamezne tipe ektomikorize in jih v naslednjem koraku identificirali še z analizo molekularnih markerjev. Z uporabljenimi pristopi smo ločili 86 tipov ektomikorize oziroma glivnih ECM-simbiontov in s tem prispevali k boljšemu poznavanju ECM-simbiontov bele jelke. Glede na do zdaj znane podatke smo kar 48 tipov ektomikorize v asociaciji z belo jelko identificirali prvič. V raziskavi so nas zanimali tudi vplivi abiotskih dejavnikov na vzorčnih ploskvah in načini, kako ti vplivajo na sestavo združb ECM-gliv in na njihove eksploracijske tipe. Potrdili smo statistično značilne razlike v sestavi združb ECM-gliv in v številčnosti eksploracijskih tipov ektomikorize med vzorčnimi ploskvami ter značilen vpliv nekaterih abiotskih dejavnikov tako na združbo ECM-simbiontov kot tudi na številčnost eksploracijskih tipov. Potrdili smo statistično značilno nihanje številčnosti tipov ECM-simbiontov ter eksploracijskih tipov med rastno sezono. V okviru raziskave smo vzpostavili lončni poskus za ugotavljanje, ali je bela jelka primeren ECM-gostitelj za nekatere vrste gomoljik (rod Tuber), in za ugotavljanje pomena deževnikov za uspešno mikorizacijo. Uspešnost mikorizacije v kontroliranih pogojih in vivo smo analizirali po 6 mesecih ter po enem letu od inokulacije s trosi vrst Tuber aestivum, T. borchii in T. melanosporum. Po enem letu od inokulacije smo potrdili, da je v naši študiji bela jelka primeren gostitelj gomoljike T. aestivum, ne pa tudi gomoljik T. borchii in T. melanosporum. Opazili pa smo negativen vpliv deževnikov na mikorizacijo in drobne korenine, kar kaže na pomanjkanje virov hrane in posledično objedanje koreninskih vršičkov.Knowledge of ectomycorrhizal (ECM) symbionts of silver fir is till date generally based on morphological-anatomical descriptions of ECM fruit bodies and/or ECM root tips, meanwhile ECM symbionts of silver fir in Slovenia have not been targeted analyzed. Within this research, silver fir’s fine roots were sampled at three climatologically and pedologically different sampling plots, where silver fir fine roots were sampled once per month during growth season, in a period of two years, and were further analyzed with stereo microscope and light microscope. Based on morphological-anatomical characteristics, individual ECM morphotypes were separated and further analyzed with molecular methods, for more reliable identification. In total, we identified 86 different ECM symbionts of silver fir, by which we contributed to better knowledge of silver fir ECM symbionts, as based on published data,48 ECM symbionts were in association with silver fir identified for the first time. We were also interested in possible significant effects of certain abiotic factors linked to individual sampling plot, on changes of ECM community composition as well as on abundances of individual exploration types. We confirmed statistically significant changes of ECM community composition and exploration types between sampled plots, by which we also confirmed significant effects of some abiotic factors as on ECM community composition as well as on abundances of exploration types. Also, statistically significant temporal changes of ECM species abundances and exploration types abundances were confirmed along to growing season. As a part of research, a pot experiment was established, by which silver fir as an appropriate host for commercially valuable truffles form genus Tuber was analyzed. Mycorrhization success in vitro was assessed after 6 months and after 1 year from spore inoculation with T. aestivum, T. borchii and T. melanosporum. At the same time, we wanted to highlight the key importance of earthworms on mycorrhization success, however after one year from spore inoculation, negative effects of added earthworms on mycorrhization level was observed, suggesting on lacking appropriate food source, which leaded to earthworms root grazing. After one year from spore inoculation, silver fir was confirmed as a appropriate host partner for truffle T. aestivum, but not also for truffles T. borchii and T. melanosporum, which\u27s presence on silver fir root tips was not observed
Hypogeous sequestrate fungi in South America – how well do we know them?
Full text linkCollecting and studying hypogeous sequestrate fungi and their particular fruiting biology has always been challenging and intriguing for scientists. However, knowledge of hypogeous taxa has for a long time been limited mainly to the Northern Hemisphere, and more recently, Australia. Nevertheless, cumulative information on sequestrate fungi for South America (SA) has increased considerably over the years, and constitutes by itself, the aim of this review. We have reviewed the available published literature, from 1880 until recent times, to extract information on records, ecology, and morphological characteristics of hypogeous sequestrate fungi from SA. Based on the 172 taxa cited in the available literature, a trend of increasing interest in the study of these fungi in the region is apparent, yet with an uneven distribution among countries, climate belts, and nature of forest habitats. Hypogeous truffle-like species in SA play a key role in regulating nutrient and carbon cycles and in all ecosystem multifunctionality. The symbiotic status is provided for most species listed, and mutualism, especially ectomycorrhizal, is predominant (82 %). The hypogeous sequestrate fungi in SA are an understudied group of fungi, with exceptional anatomical and biological features as well as in many cases intriguing phylogenetic relationships, requiring more attention and analysis from mycologists.Fil: Sulzbacher, Marcelo Aloisio. Universidade Federal de
Pernambuco. Departamento de Micologia; BrasilFil: Grebenc, Tine. Slovenian Forestry Institute; EsloveniaFil: Giachini, Admir José. Universidade Federal de Santa Catarina. Departamento de Microbiologia, Imunologia e Parasitologia; BrasilFil: Baseia, Iuri Goulart. Universidade Federal do Rio
Grande do Norte. Departamento de Botânica e Zoologia; BrasilFil: Nouhra, Eduardo Ramon. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentin
Odmrla lesna biomasa - vroča točka življenja in biotske raznolikosti gozdnih ekosistemov
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Tipi ektomikorize na bukvi (Fagus sylvatica L.) v naravnem in gospodarskem gozdu
Full text linkGlive predstavljajo ključno povezovalno biotsko komponento med posameznimi elementi gozdnega ekosistema, predvsem med viri hranil in drevesnimi partnerji v simbiozi - ektomikorizi. Spremenjene razmere v okolju, zaradi naravnih sprememb ali človekovih vplivov se odražajo tudi na ektomikorizi. Za sledenje spremembam in njihovo potencialno uporabo za mikobioindikacijo je nujno poznavanje vrstne sestave populacije ektomikoriznih gliv. V našem delu smo na ploskvah z različnimi vplivi (naravna ali antropogena sestojna vrzel, ploskev z dvakratno koncentracijo ambientalnega ozona) spremljali pojavljanje ektomikoriznih gliv na bukvi. V standardizirano odvzetih vzorcih zemlje določevali, kvantificirali, z indeksi pestrosti prikazali spremembe v populaciji ektomikoriznih gliv na bukvi in drugih drevesnih partnerjih na ploskvah ter z metodo ordinacije korelirali pojavljanje z nekaterimi lastnostmi ploskev, kjer smo odvzemali vzorce. Osredotočili smo se na čim uspešnejše določevanje tipov ektomikorize, zato smo uporabili kombiniran pristop določevanja po anatomskih lastnostih tipov in določevanje s primerjavo PCR-RFLP vzorcev z lastno bazo podatkov in s primerjavo pomnoženih nukleotidnih zaporedij z javno dostopnimi bazami. Na vseh ploskvah smo tudi popisovali in herbarizirali trosnjake ektomikoriznih in domnevno ektomikoriznih vrst gliv kot referenčni material za PCR-RFLP bazo. Različni pristopi pri določevanju ektomikorize so pričakovano rezultirali v večjem deležu do vrst ali do rodu določenih tipov ektomikorize kot v primerljivih študijah, zaradi uporabe molekularnih pristopov. Pomembna je predvsem primerjava z PCR-RFLP bazo, ki vsebuje referenčni material lokalnega izvora. V mali sestojni vrzeli smo opazili statistično značilne spremembe v pojavljanju in indeksih pestrosti predvsem v novo nastali antropogeni vrzeli Snežna jama, kjer še ni prišlo do naravne regeneracije, ki na drugih ploskvah zabriše spremembe. Na pojavljanje tipov ektomikorize ima vpliv število drevesnih patnerjev na ploskvi in prisotnost vrzeli , kar smo pokazali tudi z metodo ordinacije. Rezultati enoletnega vzorčenja na ploskvi s povišano koncentracijo ozona niso pokazali značilnih razlik v številu in vrstni sestavi tipov ektomikoriz med tretiranimi drevesi in kotrolnimi ploskvami.Fungi represent an important link between several biotic components of forest ecosystem with sources of nutrients in ectomycorrhiza. Natural or anthropogenic changes in environment can be detected as drift within functional and/or population diversity of macro- and microsymbionts. Identification of symbionts to the species level is crucial for following the drift in population structures from differently stressed plots in micobioindication approach. The aim of our research was to identify and describe species of ectomycorrhizal fungi forming symbiosis on beech and to briefly analyse ectomycorrhizae of other tree hosts from differently stressed research plots. Research plots with natural occurring or man made small canopygaps and a plot with ozonated canopies of trees, were selected. Soil samples for analysis were collected using standardised procedure. Ectomycorrhizae was identified and counted in all soil samples. Biodiversity indices were calculated and ordination method was applied to show changes in population structure of ectomycorrhizae. Combined approach for identification of ectomycorrhizae was applied with an aim to identify as many as possible different types of ectomycorrhizae to the species level. Anatomical identification in combination with PCR-RFLP and sequencing were applied. On all plots sporocarps of ectomycorrhial species were mapped and reference fungal material was stored in herbarium for build-up of PCR-RFLP database. Different approaches for identification of ectomycorrhizae resulted in higher proportion of types of ectomycorrhizae identified to the species or to the genus level in comparison to some comparable studies. The PCR-RFLP database isof high importance for identification since it contains the reference material from the same locations as an ectomycorhiza originate. Significant difference was observed in small man-made canopy gaps for occurence and diversity indices compared to plots with at least some natural regeneration. Ordination method revealed significant influence of number of tree partners and presence of canopy gap on the number of vital types of ectomycorrhizae counted in soil samples. After one year sampling on research plot fumigated with double ambient ozone concentration no significant differences were observed compared to control plot in species composition and in number of vital types of ectomycorrhizae
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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