摘要:

The generic limits ofArrheniaFries,GeotusPil. & Svr.,LeptoglossumKarsten,LeptotusKarst.,MniopetalumDonk & Singer,PhaeotellusKühn. & Lam.,PleuromycenulaSinger, andRimbachiaPatouillard are examined. Two genera,ArrheniaandRimbachia, are recognized. Keys for the species in these genera are presented and reports of the various species are reevaluated based largely on a restudy of original materials. New combinations inArrheniaare based onAgaricus fissusLeysser,Merulius lobatusPers.,Helvella retirugaBull.,Leptoglossum alnetorumSinger, andCantharellus spathulatusFr. New species combinations inRimbachiaare based onCyphella arachnoideaPeck,Agaricus bryophilusPers.,Cyphella muscicolavar.neckeraeFr.,Cantharellus furfuraceusPetch, andPleuromycenula ellipsoideaSinger.Rimbachia paludosasp. nov. is described from Ontario, Canada.Leptoglossum muscigenum(Bull.:Fr.) Karst. is a synonym ofA.spathulata(Fr.) Redhead,Mniopetalum globisporumDonk & Singer is a synonym ofR.arachnoidea(Peck) Redhead,Mniopetalum distinctumHorak is a synonym ofR.furfuracea(Petch) Redhead,Leptoglossum candidumReid is a synonym ofR.neckerae(Fr.) Redhead, andGeotus glaucussensu Pilát & Svrček 1954 is actuallyA.fissa(Leyss.) Redhead.Mniopetalum bisporumSinger is reduced to a subspecies ofR.arachnoideaandMniopetalum megalosporumSinger to a subspecies ofR.neckerae(Fr.) Redhead. In North America,Arrhenia auriscalpiumis an arctic–alpine species,A.lobatais an arctic–boreal–alpine species, andA.acerosaandA.retirugaare boreal species.Rimbachia arachnoideaandR.bryophilaare boreal species.Arrhenia spathulataandA.fissaare known only from Europe. AllArrheniaandRimbachiaspecies are bryophiles.Cantharellus polycephalusBres. is transferred toPterygellusCorner andLeptoglossum bambusicolaCorner is transferred toMarasmiellusMurrill.Pseudocraterellus leptoglossoidesCorner is a basidiolichen and the type of a new genus,SemiomphalinaRedhead.Pleuromycenula circularisSinger is transferred toHelotiumTode, andP.flavaSinger is the type of a new genus,FlabellimycenaRedhead.Campanella inquilinaRomagnesi, based onLeptoglossum conchatumsensu Romagnesi non Velenovský, is described as new.Cantharellus prescotiiWeinm., the correct name forCantharellus albidusauct. non Fries, is transferred toGerronema

ISSN:0008-4026    

DOI:10.1139/b84-126

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

The occurrence of forest fires in the Muddus National Park (area, 50 000 ha), just north of the Arctic Circle in northern Sweden, was investigated on 75 separate sample plots. Between 1413 and the present, evidence of 47 fire years was obtained by dating the fire scars on living Scots pines (Pinus sylvestris), the oldest of which had germinated in 1274. The fire traces found on the sample plots were fire scars on living or dead trees or charcoal fragments in the humus layer. Plots lacking all traces of former forest fires were mainly those situated on sites surrounded by extensive mires. Forest fires were shown to have occurred in the five different types of forest investigated. The commonest frequencies of fires in the pine forests occurred with the interval 81–90 years, while the mean frequency was 110 years. The mean interval of time elapsed since the last forest fire occurred in the pine forests was 144 years. Some of the major fire years in the Muddus area coincide with forest fires in other parts of northern Sweden, in the taiga of western Russia, and in central Siberia.

ISSN:0008-4026    

DOI:10.1139/b84-127

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

A floristic analysis of the forest vegetation of southeastern Labrador was conducted using the phytosociological methods of Braun-Blanquet and a phytosociological table was constructed with the FORTRAN program TWINSPAN, which produces hierarchical classifications by two-way indicator species analysis. A total of 88 relevés incorporating 77 species are grouped into five major assemblages: birch, fir – spruce – feather moss, spruce–fir, spruce–Pleurozium, and spruce –Sphagnum fuscumcommunities. The five communities, as arranged from birch to spruce –Sphagnum fuscum, display decreasing trends in productivity, site quality, and richness of vascular flora, and increasing prominence of oligotrophic species, primarily cryptogams and ericaceous shrubs. Black spruce and balsam fir comprise more than 95% of the forest canopy in this region, whereas paper birch is restricted to moist and well-drained slopes, and white spruce, aspen, and balsam poplar are rare. Factors suggested as responsible for the limited productivity and depauperate vascular flora of the forests in this region include: semipermanently frozen soil, short growing season, nutrient-deficient mineral substratum, and intensive root competition in the poorly aerated soil. The low incidence of fire in this maritime climate is responsible for the old and uneven age structure of the conifer forests and the development of a thick bryophyte cover and deep organic humus that limit stand productivity.

ISSN:0008-4026    

DOI:10.1139/b84-128

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

A root undergoing secondary growth exhibits massive girth increases owing to the activity of the vascular cambium. To determine the effects of this growth on endodermal structure and function, cleared cross sections from areas of primary and secondary growth in broad bean, sunflower, and garden balsam roots were examined. Casparian bands were detected by staining the sections withChelidonium majusroot extract and viewing them with ultraviolet (uv) light using an epifluorescence microscope. Endodermal diameter and numbers of endodermal cells increased dramatically in the area of secondary growth. The distance spanned by the Casparian band (i.e., the tangential width of the endodermal cells) between radial walls also increased except in sunflower. The permeability of the endodermis to an apoplastic fluorescent dye in roots undergoing secondary growth was tested by treatment with Calcofluor white M2R. In all species examined, the Casparian band continued to function as an effective apoplastic barrier during early stages of secondary growth despite the increase in endodermal cell size and number. Eventual decortication with concurrent disruption of the endodermis resulted in massive penetration of Calcofluor white M2R into the xylem.

ISSN:0008-4026    

DOI:10.1139/b84-129

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

The siliceous scales of 30 mallomonadacean taxa were identified and counted from the surficial sediments of 38 Adirondack lakes. The scales were usually abundant and were always well preserved. The Adirondack flora is typical of acidic to circumneutral oligotrophic lakes. Common taxa includeMallomonas acaroides,M.caudata,M.crassisquama,M.hamata,M.pseudocoronata,M.punctifera,Synura echinulata,S.petersenii,S.sphagnicola,S.spinosa, andChrysosphaerella longispina. The abundance of certain species (e.g.,Mallomonas hindonii,M.hamata) appears to be a reliable indication of acidic waters. Reciprocal averaging (RA) ordination was used to determine if distribution of the mallomonadacean assemblages corresponded with major environmental gradients. Correlations between the first RA axis scores and lakewater pH (r2 = 0.63) and related factors (log10alkalinity,r2 = 0.66; pCa,r2 = 0.39; pMg,r2 = 0.43) were strongest. Relationships were weaker with average depth, summer epilimnion temperature, elevation, NO3, and total Al, and were not statistically significant with conductivity, color, Secchi disc transparency, total P, chlorophylla, SO4, and Si. Cluster analysis grouped both lakes and taxa into categories best explained by their pH-related characteristics. Analysis of surficial sediment from lakes with known limnological characteristics is a useful approach for the study of the ecology and taxonomy of the Mallomonadaceae. Our data demonstrate that mallomonadacean distributions reflect lake conditions and, therefore, are potentially useful indicators in limnological and paleolimnological studies.

ISSN:0008-4026    

DOI:10.1139/b84-130

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

Variation in strains assignable to theTrichoderma longibrachiatumRifai andT.pseudokoningiiRifai species aggregates was studied. Morphological similarities allow their assignment to one section inTrichoderma, sect.Longibrachiatum, characterized and differentiated from other species ofTrichodermaby the sparsely branched conidiophores having a high proportion of solitary phialides. Cultural characteristics include very rapid growth and the production of characteristic bright yellow-green pigments visible in the colony reverse. Two new species are described in the section:Trichoderma citrinovirideBissett has ellipsoidal conidia smaller than in the other species and conidiophore branching similar to that inT.pseudokoningii;Trichoderma atrovirideBissett has relatively large, ellipsoidal conidia and a very sparse branching system with curved or sinuous conidiophores, branches, and phialides.

ISSN:0008-4026    

DOI:10.1139/b84-131

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

Ectomycorrhizae of jack pine occurring in mature stands, on bare roadsides, and in a recently burned area were compared. Fifty-six fungus associates were identified from sporocarp collections. Species ofElaphomyces,Suillus,Cortinarius,Cantharellus, and hydnums were almost exclusively limited to mature stands.Laccaria proxima,Rhizopogon rubescens.Scleroderma macrorhizon, andAstraeus hygrometricuswere typically found on disturbed sites. Visual observations and direct isolations from ectomycorrhizae further indicated that the symbionts differed between the burn site and mature jack pine – lichen woodlands. A majority of the ectomycorrhizae in all sites were nondescript and could not be identified by culturing. Unlike the vascular plants, ectomycorrhizal symbionts were very numerous without any single species or small group of species dominating jack pine root systems. Pure culture syntheses confirmed thatTricholoma flavovirens,T.pessundatum,T.zelleri,Suillus flavovirens,S.albidipes,Cenococcum geophilum,Laccaria proxima.Scleroderma macrorhizon,Astraeus hygrometricus,Lactarius paradoxus,Coltrichia perennis, andBankera fuligineo-albawere ectomycorrhizal associates of jack pine.

ISSN:0008-4026    

DOI:10.1139/b84-132

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

Leaf specific conductivities (LSCs, hydraulic conductivity per gram dry weight of supplied leaves), Huber values (transverse xylem area per gram dry weight of supplied leaves), specific conductivities (hydraulic conductivity per unit transverse xylem area), and tracheid diameters were measured throughout the trunk and erown of 9- to 96-year-old trees ofTsuga canadensis(L.) Carr. By definition, LSC = Huber value × specific conductivity. Specific conductivity is controlled by wood anatomical features, especially tracheid diameter. LSCs, which indicate the relative water supply to different plant parts, decrease acropetally but are higher in the trunk than in branches and are particularly low in second-order branches and at branch insertions. The differential water supply is due to larger Huber values in the leader and to particularly narrow tracheids at branch junctions. In addition, as trunks enlarge they produce wider tracheids, resulting in greater specific conductivity than in supported branches. Based on comparison with results forAbies balsamea, the degree of "hydraulic dominance" in the younger parts of conifers is controlled by the Huber value and may be related to the degree of apical control.

ISSN:0008-4026    

DOI:10.1139/b84-133

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

In this article, we analyse the results of the study of morphological characteristics observed in various taxons of theurinariacomplex regrouped by the authors under theUrinariaesubsection of the LinnéUrinariasection. By comparing these results with a taxonomic classification based on a previous genetic study, the qualitative analysis has shown that the discriminating characteristics in systematic units of rank equal to or higher than the species mainly belong to the reproductive apparatus. The vegetative apparatus provides only infraspecific characteristics, with the exception of pilosity and the colour of leaves common to the subsection. The quantitative analysis has shown that (i) practically all the information (90–95%) is provided by the plagiotropic branches (their length, the length of their internodes; dimension and number of their leaves) and by the pollen (dimensions); (ii) the various taxons of the subsection exhibit a wide polymorphism but, within the same population, the individuals are rather homogeneous; (iii) there exist "forms" within "lines," characterized by the size of the assimilating leaves, by the relationship between the length of the leaf and the length of the intenode, as well as by the relationship between the length of the plagiotropic branch and the number of leaves on the branch. Taking into account the results of the two preceding studies onP.urinariafrom Guyana and the Ivory Coast, these forms appear adapted to climatic factors. They are the expression, at the level of each genotype from the ecodema selected by climate, of the existence (or absence) of regulating systems allowing the adjustment of the forms to abrupt variations (natural or artificial) in external conditions.

ISSN:0008-4026    

DOI:10.1139/b84-134

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

A continuously flowing open gas exchange system was used to monitor the rates of CO2evolution, C2H2reduction, and H2evolution from intact nodulated soybean ('Harosoy 63') roots, while root temperatures were dropped from the growing temperature (25 °C) to 10 °C at the rate of 5 °C/h. FourRhizobium japonicuminoculants were used, three of which (type S (Nitragin Co.), USDA 16, USDA 35) displayed net H2evolution while the fourth (USDA 110) did not evolve H2. Between 25 and 15 °C, values for Q10in the H2-evolving symbioses ranged from 2.0 to 2.7 for CO2evolution. 1.3 to 2.4 for C2H2reduction, and 3.2 to 3.7 for H2evolution. Nodulated roots of USDA 110 displayed the highest Q10values for both CO2evolution (Q10 = 2.9) and C2H2reduction (Q10 = 15.2). The temperature profiles of these gas exchange measurements were used to calculate both the relative efficiency (RE = 1 − (H2evolution/C2H2reduction)) of N2fixation and the ratio between CO2evolution and C2H2reduction at temperatures between 10 and 25 °C. The effect of short-term changes on the CO2/C2H2ratio varied with symbiotic association. In the type-S symbiosis, long-term (96 h) treatments at low root temperature (9.5 °C) decreased the amount of CO2evolved per C2H2reduced to 35% of the value obtained at 25 °C. This study did not determine whether these observed changes were associated with N2fixation or growth and maintenance of the nodulated root. In all H2-evolving symbioses, the RE increased from ca. 0.6 to 0.9 in response to a temperature drop from 25 to 10 °C. Studies of net H2uptake and3H2exchange at 25 and 15 °C indicated that the observed changes in relative efficiency were due to variations in electron allocation by nitrogenase rather than a relative increase in uptake hydrogenase activity. The increase in RE above 0.75 suggested that lower temperatures may have altered the minimal nitrogenase electron allocation to less than one H2per N2fixed. This observed increase in RE with lower temperatures indicated that, in the symbioses studied, H2evolution may have provided a buffer which permitted the maintenance of high levels of N2fixation during short-term or diurnal fluctuations in soil temperature.

ISSN:0008-4026    

DOI:10.1139/b84-135

出版商:NRC Research Press    

年代:1984

数据来源: NRC