Low Constancy Research Articles

Relative importance of two bat species as pollinators of Neobuxbaumia tetetzo (Cactaceae): Evidences from morphometric and pollen load analyses

AbstractNeobuxbaumia tetetzo is a columnar cactus whose flowers are visited by the bat species Choeronycteris mexicana and Leptonycteris yerbabuenae. Although both bat species are considered the pollinators of N. tetetzo, the probability of pollination of each bat species has not been estimated. In this study, we determine the relative importance of C. mexicana and L. yerbabuenae as pollinators of N. tetetzo. The probability of pollination was estimated using two different approaches: (i) morphological correspondence between head (linear traits [total head length, snout length, and face height and width]) and cranial traits (shape traits) of bats and flower traits (linear [internal floral tube length including and excluding the nectary, corolla diameter, stamen length, style length, and corolla tube diameter] and shape traits), and (ii) pollen load analyses to estimate the percentage of occurrence (PO) and the pollination probability index (PPI). Our results showed a lack of a significant correspondence between both head and cranial traits of C. mexicana and the flowers of N. tetetzo, and linear morphological correspondence between total head length of L. yerbabuenae and flower length. Pollen loads of C. mexicana were composed by seven different pollen types, its PO and PPI were 41.87 ± 9.53% and 0.29, respectively. Leptonycteris yerbabuenae pollen loads were composed by three pollen types, with a PO of 78.29 ± 13.67% and a PPI of 0.67. Our results suggest that whereas C. mexicana has a low constancy to the flowers of N. tetetzo, L. yerbabuenae has a higher probability of pollination.

Species diversity of weeds in the territory of Kolpino (St. Petersburg)

Weeds are an integral part of the flora of any region. The study of the species composition of weeds not only within agroecosystems, but also on the territory of settlements allows you to obtain more complete information about the distribution of different species. The purpose of the study is to identify the species diversity of weeds and its features in the territory of Kolpino (St. Petersburg). New data have been obtained on the species diversity of weeds in the city. The analysis of monitoring data on the surveyed habitats revealed 97 species of weeds from 76 genera and 20 families. Perennial species predominate in life expectancy. A systematic structure of species composition has been established. Nine families predominant in terms of the number of species are distinguished. Calculation of occurrence and assessment of its constancy by classes were carried out. About 2/3 of the identified species have low constancy classes. Groups of 27 dominant and 19 concomitant species were identified. A relationship has been established between the species compositions of weeds in Kolpino and fields of the Leningrad Region - 84% of weeds that dominate the fields of the region are present to varying degrees in the city.

Structural Stability of Ant-plant Mutualistic Networks Mediated by Extrafloral Nectaries: Looking at the Effects of Forest Fragmentation in the Brazilian Amazon

Rainforest fragmentation drastically affects biodiversity and species composition, mainly due to habitat loss. Several studies have already shown the effects of forest fragmentation on plant and ant communities. To date, however, there is limited empirical knowledge of how forest fragmentation affects ant-plant interaction in networks. We investigated the effects of the configuration of rainforest fragments on the structure of ant-plant interaction networks mediated by extrafloral nectaries (EFNs). We carried out this study in ten forest fragments, ranging in size from approximately 5 to 3,000 ha, located in the Brazilian Amazon. In each fragment we established a plot of 6,250 m2, in which all ant-plant interactions were recorded, and calculated the following network descriptors: number of interactions, network size, network specialization, diversity of interactions, and nestedness. We used four explanatory variables to investigate the effects of forest fragmentation on these network descriptors: three metrics of the configuration of fragments (i.e., fragment area, edge irregularity, and connectivity) and the forest structure within each fragment, represented by canopy cover. We did not detect any effect of the explanatory variables on the network descriptors. The structural stability of the networks sampled in forest fragments with different configurations is possibly related to the observed constancy of ant species in the central core of highly interacting species. Our results corroborate other studies highlighting the structural stability of these facultative ant-plant networks mediated by EFNs in different spatial and temporal gradients. Nonetheless, the low constancy of plant species in the generalist core should be understood as a warning, mainly because the functionality of this protective mutualism (i.e., food secretions in exchange for protection against herbivory) remains unknown.

Functionally similar species of ciliates have similar dynamics: A biennial survey study in a large eutrophic lake

The spatial and temporal planktonic ciliate community structure of a large shallow eutrophic lake was described in detail based on a monthly monitoring campaign over 2 years using the quantitative protargol stain approach. We found that there was a large variety and low constancy of ciliate plankton and a clear advantage of several small species. Balanion planctonicum, Rimostrombidium brachykinetum, and Urotricha farcta contributed 19.7%, 13.4%, and 10.7% to the total abundance, respectively. The ciliate community was significantly varied in different lake regions of different eutrophication levels, and the distribution of some of the main species, especially prostomatids and scuticociliatids, might be closely related to the nutrient level of the lake regions. The seasonal dynamics of ciliate taxa with similar functional feeding habits across regions at different trophic levels are more convergent than those of species with very different functions, and the top-down effect (cladocerans, rotifers), nutrition, and water temperature were the key factors shaping ciliate community structure. The results of this study accentuate the important effects of species functional diversity on community differences and may improve our knowledge of ciliate diversity and functional ecology in shallow eutrophic lakes.

Phytocoenotical behaviour of boreal plant species in broadleaved-forest zone communities

Phytocoenotic behaviour of 11 species of boreal vascular plants and mosses is analyzed within the broadleaved-forest zone in comparison with that in different subzones of the boreal-forest zone, based upon the set of 1417 relevés made in European Russia in 1996–2017. The significance of differences in species cover is estimated by means of the one-way ANOVA. The cover of species like Vaccinium myrtillus, V. vitis-idaea, andHylocomium splendens in broadleaved / spruce forests of zonal types is constantly decreasing southwards. On the contrary, the cover of Luzula pilosain Scots pine forests and Pleurozium schreberi and Dicranum polysetum in paludified Norway spruce forests is subject to southward increase. Finally, Oxalis acetosella and Equisetum sylvaticum demonstrate maximae of their cover in forests of zonal types in the southern-boreal and hemiboreal subzones. The dark-coniferous boreal forest “cortege” of species is breaking down into several different floristic elements in the broadleaved-forest zone. These are: “vaccinietal” species p. p. sensu Yu. D. Kleopov (like Vaccinium myrtillus), “quasi-boreal” species sensu V. B. Sochava (Oxalis acetosella, Maianthemum bifolium, Trientalis europaea), hygromesophytes with aged areas (Equisetum sylvaticum), associated species with European-Ancient-Mediterranean nemoral (Luzula pilosa) or East-Asian boreal-montane (Rubus saxatilis) origins. Phytocoenotical behaviour of species is not always different in the intrazonal and the zonal community types but is rather similar in many cases like those of Vaccinium vitis-idaea and Equisetum sylvaticum. The more distinct differences in species positions are found in the extrazonal communities. The statistically proved differences are lacking in phytocoenotical behaviour of Maianthemum bifolium and Trientalis europaea in different zones and subzones due to either florogenetical, or purely methodical reasons, the latter connected with low abundance but high constancy of these species. Disintegration of vegetation “corteges” and individualization of coenotic patterns of species previously growing together are usually observed at the climatically determined (zonal / subzonal or altitudinal) distribution limits.

Exploring siRNA Umpired Nanogels: A Tale of Barrier Combating Carrier.

Potential short interfering RNAs (siRNA) modulating gene expression have emerged as a novel therapeutic arsenal against a wide range of maladies and disorders containing cancer, viral infections, bacterial ailments and metabolic snags at the molecular level. Nanogel, in the current medicinal era, displayed a comprehensive range of significant drug delivery prospects. Biodegradation, swelling and de-swelling tendency, pHsensitive drug release and thermo-sensitivity are some of the renowned associated benefits of nanogel drug delivery system. Global researches have also showed that nanogel system significantly targets and delivers the biomolecules including DNAs, siRNA, protein, peptides and other biologically active molecules. Biomolecules delivery via nanogel system explored a wide range of pharmaceutical, biomedical engineering and agro-medicinal application. The siRNAs and DNAs delivery plays a vivacious role by addressing the hitches allied with chronic and contemporary therapeutic like generic possession and low constancy. They also incite release kinetics approach from slow-release while mingling to rapid release at the targets will be beneficial as interference RNAs delivery carriers. Therefore, in this research, we focused on the latest improvements in the delivery of siRNA loaded nanogels by enhancing the absorption, stability, sensitivity and combating the hindrances in cellular trafficking and release process.

Как погрешности при описании растительности в поле и обработке данных влияют на результаты классификации (на примере арктических сообществ)

Как погрешности при описании растительности в поле и обработке данных влияют на результаты классификации (на примере арктических сообществ)

Зональная растительность равнинных восточноевропейских тундр

Зональная растительность равнинных восточноевропейских тундр

Influence of Clear Fellings on the Bryophyte Component of the Broad-leaved Forests of the Bashkir Cis-Ural Region

The change in the composition of the bryophyte component of succession communities that occur in the process of natural regeneration at the site of clear felling of the indigenous elm—maple–linden forests of the Bashkir Cis-Ural Region has been studied. The vulnerability of species to the consequences of felling is affected by their substrate confinement, ecological amplitude in relation to the factors of temperature, humidity, variability of soil moisture, and type of life strategy. In the secondary aspen forests, the absence or low constancy of nemoral epiphytic and ground mosses was noted.

Predatory risk favours intermittent incubation of a colonial burrowing shorebird, the Crab Plover Dromas ardeola

Intermittent incubation in birds is currently interpreted as the result of trade-offs between the needs of the embryo and those of the parents. However, the low nest attendance in some species is still puzzling. We studied the Crab Plover (Dromas ardeola), a tropical burrow nesting shorebird with very low incubation constancy (less than 55%) due to frequent recesses from incubation (on average 5 recesses/h), mostly spent in the colony area without any apparent function. We aimed to test whether such unusual incubation rhythm can be partly explained by the need to scan for approaching predators. Data collected at Dahret Island (Eritrea) between 2006 and 2014 support the antipredatory function of the incubation rhythm: (1) many recesses on the colony surface were so short (50% less than 37 s in the hotter periods) that a thermoregulatory function can be dismissed; (2) adults on the colony surface responded to approaching predators with alarm calls that drove most incubating Crab Plovers to run out of the burrows and to escape in flocks; (3) sound intensity sharply decreased inside burrows, which explains the delayed escape observed for 9% of the incubating birds; (4) the delayed exit when predators were still in the colony area rules out their permanence inside burrows as an alternative antipredatory strategy; (5) after the visit of a predator, adults restarted incubation with very short in-bouts (2 min on average) apparently in order to scan frequently for approaching predators. We discuss how burrow nesting, alarm calls, and the antipredatory reactions of adults (escape into or out of the burrows, flock flight, mobbing) and chicks (escape into burrows) might have favoured colonial breeding in Crab Plovers.

Синтаксономия степной растительности Республики Бурятия

Синтаксономия степной растительности Республики Бурятия

Растительность залежей центральной части музея-заповедника «Куликово поле» (Тульская область)

The museum-preserve «The Kulikovo Field» is situated in the northern part of the Central Russian Upland within the forest-steppe zone near its northern border. There are a lot of abandoned fields, most of them left fallow since 1990–2000 years; the exact age of the old fields is unknown. Using the Braun-Blanquet approach as well as the method of K. Kopecký and S. Hejný (Kopecký, Hejný, 1974; Kopecký, 1992), the classification of the old-field vegetation of the central part of the museum-preserve was carried out. One derivate community, 2 basal communities (one of them with two variants), 3 communities and one association with three variants have been identified. The derivate community Conyza canadensis­ [Artemisietea vulgaris/Stellarietea mediae] is dominated by annual and biennial ruderal species: Conyza canadensis, Lactuca serriola and Carduus acanthoides. The association Convolvulo arvensis–Elytrigietum repentis is heterogeneous both in its floristic and subdominant composition and it can be divided into 3 variants. The variant typica represents monodominant communities where Elytrigia repens prevails. The variant Lactuca serriola is characterized by high constancy of Conyza canadensis, Lactuca serriola and some other ruderal plants and it represents coenoses dominated by Elytrigia repens with subdominants such as Lactuca serriola, Senecio jacobaea and Pilosella spp., mainly P. bauhini. The variant Cichorium intybus is dominated by Elytrigia repens with a subdominant Cichorium intybus; some mesophilous meadow species are often present. Variants Melilotus officinalis and Sonchus arvensis of the basal communityElytrigia repens–Cichorium intybus [Artemisietea vulgaris] are dominated by Cichorium intybus, Poa angustifolia and Elytrigia repens, the first of them also by Melilotus officinalis, Artemisia absinthium, and the second by Carduus acanthoides and Calamagrostis epigeios. Unlike the foregoing syntaxa the basal community Elytrigia repens–Cichorium intybus [Artemisietea vulgaris] is characterized by relative high constancy of some species pertaining to the order Galietalia veri, namely Fragaria viridis, Galium verum, Potentilla argentea. These species and also Poa angustifolia are the first steppificated meadow plants that appear in the old field communities under investigation. The community Pilosella bauhini [Onopordion acanthii] is dominated by Pilosella spp., mainly by P. bauhini that sometimes replaced by some ruderal plants, e. g. Achillea nobilis or Cichorium intybus. The peculiarity of this community is the low constancy and abundance of Elytrigia repens. The species of the orders Galietalia veri and Arrhenatheretalia play much noticeable role in the other syntaxa mentioned below, so these syntaxa are between the natural and synanthropic vegetation. The community Leucanthemum vulgare–Galium mollugo [Onopordion acanthii/Molinio-Arrhenatheretea] is distinguished by high abundance and constancy of some mesophilous and xeromesophilous meadow plants (Leucanthemum vulgare, Galium mollugo, Phleum pratense etc.). The community Artemisia marschalliana [Onopordion acanthii/Galietalia veri] is dominated mostly by Leontodon hispidus and Pilosella spp.; its peculiarity is a relatively high constancy of species common in the local steppificated meadows. The basal community Poa angustifolia [Galietalia veri/Artemisietea vulgaris] represents monodominant communities where Poa angustifolia prevails. Annual, biennial and some perennial ruderal species are rare in this variant, unlike most of the syntaxa mentioned above. The common feature of the last three syntaxa is subdominance of Fragaria viridis. It is known that the floristic composition of communities is changed during an old-field succession: the percentage of annual and biennial species declines and that of species pertaining to the classes of natural vegetation increases (Bonet, Pausas, 2007; Yamalov et al., 2008; Pankratova, Gannibal, 2009). Using the life-form and phytosociological spectrum of the syntaxa analysis an attempt to evaluate succession status of the described communities was made (tab. 9, 10). Based upon the results of this analysis, it is possible to suggest that the derivate community Conyza canadensis [Artemisietea vulgaris/Stellarietea mediae] is the earliest stage one can find in the investigated old fields. The variants Lactuca serriola and typica of the association Convolvulo arvensis–Elytrigietum repentis and the community Pilosella bauhini [Onopordion acanthii] are the next in the series. It seems that Pilosella spp. (P. bauhini and probably some other species of this genus) outcompete the pioneer species of initial stages, like Elytrigia repens, in some cases. The basal community Poa angustifolia [Galietalia veri / Artemisietea vulgaris] seems to be the most advanced stage: the percentage of annuals and biennials is minimal, and that of species pertaining to the syntaxa of natural vegetation of the high ranks, especially to the order Galietalia veri, increases greatly. Species richness of the communities is minimal at the most early stage, which is the peculiarity of the old-field vegetation (Pankratova, Gannibal, 2009; Ovcharova, Yamalov, 2013). Similar phenomenon was also noticed at the succession stages where strong dominant (Elytrigia repens or Poa angustifolia) pre­vails, regardless of how much advanced these stages are, the fact mentioned earlier (Prach, 1985). Species richness attains maximum at those stages of succession where the communities are polydominant and contain both early- and late-successional species, that was also previously described (Meiners et al., 2007).

Anti-herbivory defense of two Vicia species with and without extrafloral nectaries

The effects of direct and indirect defenses differ among plant species, and the variation in the mode of plant defenses might reflect physiological and/or ecological constraints of each mode of defense related to the growth and reproduction of individual plant species. To evaluate the advantages and disadvantages of indirect ant-mediated defense via extrafloral nectaries (EFNs), we compared the herbivory pressure, leaf chemicals, vegetative growth, and reproduction between two species of vetches, Vicia sativa var. angustifolia (Reichard) Wahlenb (Leguminosae) with EFNs and V. hirsuta (L.) SF Gray without EFNs (or with very small EFNs). Indirect ant defense of V. sativa was not consistently reliable because of the low constancy of ant attraction. In addition, V. sativa was more vulnerable to attack by herbivores than V. hirsuta. The estimated total amount of sugars secreted by EFNs of V. sativa corresponded to 0.5% of total leaf biomass, and 0.07% of total plant biomass, indicating a low investment to the production of extrafloral nectar. Vicia sativa plants grew more rapidly than V. hirsuta plants during the reproductive stage. Therefore, we consider that V. sativa adopts the ant defense via EFNs in spite of its low reliability because the indirect ant defense supported by EFNs requires only low investment, allowing the plants to attain rapid growth in the early spring.

Классификация растительности острова Врангеля

The syntaxonomical study of Wrangel Island carried out in accordance to Braun-Blanquet approach is proposed. As a result 29 associations, 1 type of com­munity, 18 subassociations, 8 variants and 5 facies are distinguished. A series of associations belong to 13 allian­ces, 12 orders and 9 classes which were des­cribed earlier (some of them are provisional). The procedure of classification have showed some metho­dical difficulties. One of them is the revealing of be­longing syntaxa to any class, a lot of which were described in more south regions. As a result much of diagnostic species of these classes are absent in arctic regions. So far as many species of Arctic characterized by wide distribution they cannot be used as character species. The concept of vicariant syntaxa is used: 5 associations are considered as vicariants of syntaxa already distinguished. At present there are not any higher syntaxa (class) for correct description for zonal (plakor) vegetation, erect shrubs and zoogenic vege­tation in arctic tundra subzone. The syntaxa of Carici rupestris—Kobresietea bellardii and Thlaspietearotun­difolii predominate in island. There are north limits of areas of some syntaxa such as ass. Sphagno—Eriopho­retum vaginati vic. Polytrichastrum alpinum, Bra­chy­thecio salebrosi—Salicetum glaucae, Parryo nudicau­lis—Salicetum lanatae, Equisetetum borealis vic. Polemonium acutiflorum on Wrangel Island. Zonal associations are characterized by lowest number of character species (2—4). The reason of this pheno­mena is the average meaning of ecological parameters in plakors. As a consequence many species of different ecological groups can growth together. There are fr om 9 to 17 character species in some intrazonal associa­tions: Carici membranaceae—Dryadetum integri­foliae, Castillejo elegantis—Caricetum rupestris, Salici calli­carpaeaе—Dryadetum chamissonis, Arte­misio borea­lis—Chamaenerietum latifolii. Following associations of plakor are characterized by the highest species richness: Parryo nudicaulis—Dryadetum punctatae (255 taxa) and Artemisio ti­lesii—Deschampsietum borealis (250). Besides these the ass. Salici polaris—Caricetum podocarpae which is formed in snowbed sites have 251 taxa. A lot of species have middle (III) or low (II, I) constancy. The higher number of species in syntaxa compared to community is due to rare species. The coverage of majority of species varies from <1 % to 5 %, not more than 10 species — from 6 % to 12 %. Only 3 species form an stable coverage more than 25 %: Carexlugens, Dryaspunctata, D. inte­grifolia. Two types of community are characterized by the homogeneous cover: ass. Meesio triquetris—Caricetum stantis vic. Warnstorfia sarmentosa and ass. Salici polaris—Caricetum podocarpae. The tundra turf is heterogeneous in zonal (plakor) communities. It consists of different fragments of mosses, lichens and vascular plants. Frost boils (patches) are most common elements of horizontal structure. The turf around patches forms continuous net. Non closed (open) communities are predominate at all slopes, tops and mountain terraces. Cushions formed by herbs Artemi­siaborealis subsp. richardsoniana, A. glo­merata, Oxytropisgorodkovii, Potentillasubvahliana are usual in such sites. There are 2 layers in com­munities: an upper one (10—30 cm) wh ere herbs are predominate and dwarf shrubs-lichen-moss (less than 10 cm). The height of shrub Salixlanata subsp. richard­sonii layer at the center of island is 45—60 cm.

Reproductive strategy of a small endemic cyprinid, the Yarqon bleak (Acanthobrama telavivensis), in a mediterranean-type stream

A mediterranean-type climate exists in five widely separated regions; the Mediterranean basin, parts of western North America, parts of western and southern Australia, southwestern South Africa and parts of central Chile. Streams in these regions feature seasonal disturbances of contrasting hydrology with high predictability of the timing of flooding and drying but low constancy. We would expect fish living in these streams to avoid scouring flow and breed after cessation of the flood period. The aim of the present study was to examine the adaptation of the Yarqon bleak, Acanthobrama telavivensis, an endemic cyprinid in the coastal streams of Israel, to mediterranean-type stream (mediterranean—written with a small m, is used in connection with climate or ecological region and is distinguished from Mediterranean that is used in a geographical context, referring to the Mediterranean basin.) conditions. For that we studied its reproductive strategy (age at maturity and life span, gonad activity, oocyte maturation, spawning activity and habitats, appearance of juveniles), in a major costal stream (Yarqon). Our findings show that the Yarqon bleak exhibits life history traits attuned with a mediterranean-climate hydrologic regime. It breeds in late winter and early spring, a window of opportunity between flash floods and habitat desiccation. Being a multiple spawner allows the fish to compensate for the potential loss of part of its reproductive output due to scouring flows of late floods. The ability of the Yarqon bleak to spawn on different substrate-types enables it to take advantage of different stream conditions that pertain in different years. The fish attains pre-adult size (ca. 33–42 mm) within the first year, prior to drying out of most stream reaches, and matures by the beginning of the second year (males >41; females >42 mm). The cost of these tactics is a short life span (4–5 age groups). The reproductive strategy of the Yarqon bleak falls into the category of in-channel breeding but, unlike the case suggested by a low flow recruitment model, the fish breed during the period of flood cessation, a transitional time between high and low flows, rather than at the time of low flow. Breeding at this time of the year in mediterranean-type streams puts early stages somewhat at risk of being washed away by late floods, but gains them a longer period of growth under favorable conditions. We suggest an additional positive tradeoff that should be investigated: the reduced competition with age 0 of other fish that breed later in the season. This suggested model of recruitment during the period of flood cessation seems appropriate for fish in streams with seasonal contrasting flows of high predictability but low constancy.

Does forest type and vegetation patchiness influence horizontal distribution of soil Collembola in two neighbouring forest sites?

The influence of forest type and heterogeneity of understory vegetation on the horizontal distribution of soil living Collembola was studied in two neighbouring mountain forest sites—a 180-year old beech forest and a 70-year old natural spruce forest. Four homogenous patches with different understory vegetation were chosen within each forest site and sampled 12 times between 1997 and 1998. A total of 56 collembolan species were identified, 51 in the beech forest and 48 in the spruce site. Twenty-three species were rare—they were recorded with low constancy and density. Although both forest sites differed in soil type, humus form and soil chemical parameters, the species composition of their collembolan communities was quite similar (77% shared species). Nevertheless, soil collembolan communities of both forest sites were clearly delimited on both qualitative (presence–absence) and quantitative (in density of individual species) levels as well as in terms of total collembolan density. Mean collembolan density reached 26 650–44 030 ind/m 2 in the beech patches compared to 44 470–68 050 ind/m 2 found in the spruce patches. Considerably higher densities of several species in one forest site may indicate more suitable habitat. In spite of similar species composition and minor differences in qualitative parameters among different vegetation patches within one forest site, there was clear variation in density of individual species, particularly between patches with and without herb vegetation. This could reflect different microclimatic conditions, additional litter supply from herbs or indirect interactions of Collembola with their roots.

Briza media L.

A loosely tufted perennial with short rhizomes from which arise vegetative shoots. Culms 15-60 (-100) cm high, slender, erect, 2-3-noded, solitary, smooth. Leaves with dull glaucous to mid-green adaxial and abaxial surfaces, hairless; blades usually 4-20 (-28) cm long, 2-4 (-7) mm wide, with minute acroscopic teeth on the margins, with a slender boat-shaped tip; ribs numerous, closely packed, less obvious on the abaxial surface; sheaths smooth, entire, soon splitting, dark reddish-brown at base; ligules up to 1.5 mm long, membranous, blunt with irregular margins. Culm leaves 3 or 4, uppermost with long sheaths. Panicles 410 (-18) cm long, lax, roughly pyramidal, with up to 20 branches, and up to 60 spikelets, sparsely divided, spreading, with scabrous hair-like pedicels 5-20 (-50) mm long and slightly thickened below the spikelets. Spikelets 4-7 mm long and wide, loosely scattered and drooping, broadly elliptic to broadly ovate, laterally compressed, generally purplish-brown, usually breaking up at maturity beneath the lemmas but many spikelets remaining undispersed on the branches and shed from the panicle intact, 4-9 (-12)-flowered. Glumes slightly unequal, deeply concave, hooded at the apex, boat-shaped, 2.5-3.5 mm long, with 3-5 veins, firmly membranous, dull-purple with white and shiny margins. Lemmas 3.7-4.1 mm, strongly cordate at the base, bluntly keeled in the lower half, closely overlapping, rounded on the back, with 7-9 veins, variegated purple and green, with hyaline margin. Paleas flat, thin, almost as long as the lemma, with two keels, narrowly winged. Lodicules 2, linear-lanceolate, acute. Grain enclosed within the papery lemma and palea, c. 2 mm long, rounded on the back, flattened on the front; mean oven-dry weight 0.53 mg. The root system is a dense mat of whitish fibrous roots. The primary roots are up to 1 mm in diameter and are largely unbranched, but there is a dense network of branching secondary roots. The root mass is fairly vertical with an average root length of c. 40 cm. The species produces pale brown rhizomes up to 13 cm long and 1.5 mm in diameter. Native. Subspecies media occurs throughout the range; subspecies elatior (Sibth. & Sm.) Rohlena occurs in south-east Europe.

Koeleria macrantha (Ledeb.) Schultes (K. alpigena Domin, K. cristata (L.) Pers. pro parte, K. gracilis Pers., K. albescens auct. non DC.)

<i>Koeleria macrantha</i> (Ledeb.) Schultes (<i>K. alpigena</i> Domin, <i>K. cristata</i> (L.) Pers. pro parte, <i>K. gracilis</i> Pers., <i>K. albescens</i> auct. non DC.)

The Influence of Female Age, Body Mass, and Ambient Conditions on Redhead Incubation Constancy

Incubation constancy, i.e., the proportion of time on the nest, of female Red-heads (Aythya americana) was examined during the summers of 1995 and 1996 in relation to female age, body mass, and ambient conditions. Redhead females exhibited one of the lowest incubation constancy (82%) among duck species (Anatidae), coupled with a comparatively high number of incubation recesses per day. Low constancy was not due to excessive disturbance at the nest or reduced maternal investment in the clutch, but was probably related to energetic constraints of the female imposed by laying parasitic eggs prior to nesting. As in most other duck species, incubation constancy decreased over the incubation period. Age, mass, and maximum daily temperature, and the interactions of initiation day X age and mass X date significantly influenced daily incubation constancy. Constancy was higher for older females and for females of lower body mass and was lower on days with higher maximum daily temperatures.

The study of macrofungal communities: defining adequate sampling units by means of cluster analysis

A fungus-biotope and a cluster analysis of macrofungal communities were done across a sequence of four forest associations in the Laurentide Mountains of Quebec. Comparison between different scales of sampling indicated that the cohesion and individuality of macrofungal clusters tend to increase from the whole mycoflora of a site toward trophic group and niche group levels. At this latter level, the reliability of defined communities is however highly limited by the low species richness and low constancy of their species. Four sampling units of fungi on the forest floor, were defined: ectomycorrhizal, humicolous, folicolous-muscicolous and lignicolous. This division further contributes to define the natural assemblages of fungi within the biocoenose.