Germination and seed water status of four grasses on moss-dominated biological soil crusts from arid lands

Biological soil crusts dominated by drought-tolerant mosses are commonly found through arid and semiarid steppe communities of the northern Great Basin of North America. We conducted growth chamber experiments to investigate the effects of these crusts on the germination of four grasses: Festuca idahoensis, Festuca ovina, Elymus wawawaiensis and Bromus tectorum. For each of these species, we recorded germination time courses on bare soil and two types of biological soil crusts; one composed predominantly of the tall moss Tortula ruralis and the other dominated by the short moss Bryum argenteum. On the short-moss crust, the final germination percentage was about half of that on bare soil. Also, the mean germination time was 4 days longer on short-mosses than on bare soil. In contrast to the short-moss crust, the tall-moss crust did not reduce the final germination percentage but increased the mean germination time. Similar results were observed in the four grasses studied. To investigate the mechanism by which moss crusts affected germination, we analyzed the water status of seeds on bare soil and moss crusts. Six days after seeding, the water content of seeds on bare soil was approximately twice that of seeds on tall- or short-moss crust. Analysis of the time course of changes in seed weight and water potential in Bromus tectorum revealed that overtime seeds on tall mosses reached higher water content than those on short mosses. The increase in the water content of seeds on tall mosses occurred as the seeds gradually fell through the moss canopy. Taken together, our results indicate that biological soil crusts with distinct structural characteristics can have different effects on seed germination. Furthermore, this study revealed that a biological soil crust dominated by short mosses had a negative effect on seed water status and significantly reduced seed germination.     

Arbuscular mycorrhizal structure and fungi associated with mosses

We investigated the colonization and diversity of arbuscular mycorrhizal (AM) fungi associated with 24 moss species belonging to 16 families in China. AM fungal structures, i.e. spores, vesicles, hyphal coils (including intracellular hyphae), or intercellular nonseptate hyphae, were found in 21 moss species. AM fungal structures (vesicles, hyphal coils, and intercellular nonseptate hyphae) were present in tissues of 14 moss species, and spores and nonseptate hyphae on the surface of gametophytes occurred in 15 species. AM fungal structures were present in 11 of the 12 saxicolous moss species and in six of the ten terricolous moss species, but absent in two epixylous moss species. AM fungal structures were only observed in moss stem and leaf tissues, but not in rhizoids. A total of 15 AM fungal taxa were isolated based on trap culture with clover, using 13 moss species as inocula. Of these AM fungi, 11 belonged to Glomus, two to Acaulospora, one to Gigaspora, and one to Paraglomus. Our results suggest that AM fungal structures commonly occur in most mosses and that diverse AM fungi, particularly Glomus species, are associated with mosses.     

Effect of desert soil algae on the stabilization of fine sands

Four filamentous cyanobacteria, Microcoleusvaginatus, Phormidium tenue,Scytonemajavanicum (Kutz.) and Nostoc sp., and asingle-celled green alga, Desmococcus olivaceus, allisolated from Shapotou (Ningxia Hui Autonomous Region of China), were batchcultured and inoculated onto unconsolidated sand in greenhouse and fieldexperiments. Their ability to reduce wind erosion in sands was quantified byusing a wind tunnel laboratory. The major factors related to cohesion of algalcrusts, such as biomass, species, species combinations, bioactivity, niche,growth phase of algae, moisture, thickness of the crusts, dust accretion(including dust content and manner of dust added) and other cryptogams(lichens,fungi and mosses) were studied. The best of the five species were M.vaginatus and P. tenue, while the best mix wasablend of 80% M. vaginatus and 5% each of P.tenue,S. javanicum,Nostocsp. and D. olivaceus. The threshold friction velocity wassignificantly increased by the presence of all of the cyanobacterial species,while the threshold impact velocity was notably increased only by thefilamentous species. Thick crusts were less easily eroded than thin crusts,while biomass was more effective than thickness. Dust was incorporated bestintoMicrocoleus crust when added in small amounts over time,and appeared to increase growth of the cyanobacterium as well as strengthen thecohesion of the crust. Microbial crust cohesion was mainly attributed to algalaggregation, while lichens, fungi and mosses affected more the soil structureand physico-chemical properties.     

Response patterns of net photosynthesis to moisture of mosses in xeric habitats

The response patterns of net photosynthesis to moisture level of mosses in xeric habitats were compared with those in mesic habitats, in order to determine whether the former species are better adapted to the xeric condition with regard to carbon gain. Moss species examined wereRhacomitrium lanuginosum andR. barbuloides in xeric open habitats andDicranum japonicum, Hypnum plicatulum, Ptilium crista-castrensis, Pleurozium schreberi andHylocomium splendens in mesic habitats on the coniferous forest floor in the upper subalpine zone of Mt. Fuji. Three additional xerophytic species collected at other localities,Ptychomitrium polyphylloides, Grimmia pilifera andHedwigia ciliata, were also examined. Five species in the xeric habitats showed an optimum range of moisture level for net photosynthesis, 2 to 3g·g⁻¹. On the other hand, species in the forest showed a wider optimum range, 3 to 8g·g⁻¹. Net photosynthetic rate at the moisture level of 0.5g·g⁻¹ was positive in xerophytic mosses, but negative in most forest mosses. Moisture levels where external capillary water disappeared and drop of water potential began was determined by blotting water-saturated shoots with membrane filters. These moisture levels were low in the xerophytic mosses and high in the forest mosses, although there were some exceptions. It was concluded that mosses in xeric habitats are better adapted for the efficient use of water for photosynthesis than those in mesic habitats.     

The broad-scale distribution of microfungi in the Windmill Islands region, continental Antarctica

Microfungi were isolated from soils, mosses, algae and lichens in the Windmill Islands region of Antarctica. From a total of 1,228 isolates, 22 genera were identified. The most frequently isolated fungi from mosses were Mycelia sterilia (47% of total isolates), Phoma spp. (18%), Penicillium spp. (11%), Chrysosporium spp. (7%) and Thelebolus microsporus (6%). Mycelia sterilia, Penicillium spp., Mortierella spp., Chrysosporium cf. pannorum and Thelebolus microsporus were also frequently isolated from algae. Fungal distribution and diversity were poor in samples of lichens, compared to samples from mosses and algae. The frequency of occurrence of microfungi was most often associated with strong biotic influence. There was a marked increase in fungal diversity in human-disturbed sites. Twelve taxa were restricted to soils from near the Australian Casey Station, suggesting significant introduction of fungi into this environment by human activities. Away from the station, fungal distribution appeared to be related to substrata and nutrient status rather than dispersal opportunities. Suggestions for future research and the need for constant monitoring to clarify the role of human disturbance on Antarctic fungi are discussed. Received: 1 April 1997 / Accepted: 17 August 1997     

Determination of Prenylquinones in Green Photosynthetically Active Moss and Liver Moss Tissues

The prenylquinone composition of two species of mosses (Polytrichum formosum Hedw., Sphagnum acutifolium Ehrh.) and two species of liver mosses (Lunularia cruciata (L.) Dum., Pellia epiphylla (L.) Cord.) was determined and compared with the chlorophyll content and the photosynthetic activity of the intact moss and liver moss tissues.

• 1 Green moss and liver moss tissues possess in principle the same prenylquinone composition as higher plants with plastoquinone-9, α-tocopherol, α-tocoquinone and the phylloquinone K₁ as main components. On a chlorophyll basis the lipoquinone levels are lower than in higher plants. Differences among the individual mosses as well as within one species only occur in the quantitative levels of the chloroplast prenylquinones, but there are no differences between musci and liver mosses.
• 2 There are differences in the maximal fluorescence of liver mosses and mosses. The variable fluorescence in turn, which is a measure of in vivo photosynthetic activity, is very similar for all examined species of mosses and liver mosses (values from 0.7 to 1.0) but somewhat lower than in leaf pieces of higher plants. DCMU blocks the variable fluorescence and the concomitant oxygen evolution in all mosses and liver mosses.
• 3 From the lower prenylquinone levels and the low values for the variable fluorescence it is concluded that mosses and liver mosses exhibit on a chlorophyll basis fewer reaction centres and electron transport chains than chloroplasts of higher plants.

     

黄土丘陵区6种侧蒴藓类植物营养繁殖特征

侧蒴藓类植物是苔藓植物中体型较大的类群,形态结构复杂,在水土保持、水源涵养等方面有巨大的应用潜力。该研究以黄土丘陵区6种常见侧蒴藓类植物为材料,采用人工气候室培养,研究了不同侧蒴藓类植物营养繁殖特征及种间差异。结果显示：（1）6种侧蒴藓类植物具有较强的繁殖能力,平均10 d和17 d均萌发新配子体和原丝体;营养繁殖中,6种藓新配子体萌发时间早于原丝体,其中青藓（Brachythecyum albicans）的新配子体萌发最早,镰叶灰藓（Hypnum bambergeri）萌发最晚。（2）6种藓新配子体的发枝长度、发枝数量在培养过程中均呈先增加后平稳的趋势,发枝长度在萌发后第21天均趋于平稳,发枝数量在第28天时均趋于平稳;藓盖度除柳叶藓（Amblystegium serpens）在培养结束前继续增加外其余藓种在生长42 d后趋于平稳,其中青藓的发枝长度、发枝数量、盖度增幅最明显,分别较萌发前增加4.73 mm、1.53条、46.22%。（3）6种藓盖度、新配子体发枝长度及发枝数量的增长速率差异显著,其中青藓3个指标的增长速率均显著高于其他藓种（P<0.05）,分别为0.97%·d^-1、0.24 mm·d^-1和0.101 条·d^-1。发枝长度增加速率最慢的是鳞叶藓（Taxiphyllum taxirameums）,为0.17 mm·d^-1、发枝数量增加速率最慢的是镰叶灰藓,为0.041条·d^-1、盖度增加速率最慢的是荫地绢藓（Entodon caliginosus）,为0.46%·d^-1。结果表明,黄土丘陵区6种常见侧蒴藓类植物通过人工培养均可进行营养繁殖,但营养繁殖存在种间差异,其中青藓的营养繁殖能力优势显著。本研究明确了侧蒴藓类植物营养繁殖特征及人工培养的可能性,可为该藓类植物在水土保持及生态恢复中的应用提供科学依据。     

CO2-Gaswechsel von Moosen nach Wasserdampfaufnahme aus dem Luftraum

Summary The CO₂-gas exchange of dry mosses which were exposed to air of high water vapour content has been followed. Some moss species behave as do lichens and aerophilic green algae: they are able to take up enough water vapour to make a rather high photosynthetic activity possible. Other species lack this ability. They need liquid water for reactivation of photosynthesis, as do poikilohydric ferns and phanerogams. In this respect too the mosses are located between the real thallophytes and the cormophytes. From this point of view they are useful objects for studying the relationships between water vapour reactivation, morphological organisation and ecological capability.     

Moss diatom communities from Ile de la Possession (Crozet,Subantarctica) and their relationship with moisture

More than 190 taxa, belonging to 33 genera, were observed on mosses collected on Ile de la Possession, Crozet Archipelago, Antarctica. Six assemblages could be identified. Habitat type and moisture content of the samples appeared to be the major factors in separating the communities. It was clear that diatom communities growing on mosses found in rivers and brooks are different from assemblages on rocks and in stagnant pools. The Diadesmis contenta assemblage was bound to dry mosses growing on rocks whereas the Eunotia paludosa var. paludosa community preferred acid stagnant pools, situated in the larger valleys. The other four assemblages are typical for circumneutral waterbodies, with the Fragilaria maillardii and the Fragilaria vaucheriae-Fragilaria germainii assemblages found in running water and the Fragilaria pinnata var. pinnata and the Achnanthes confusa-Achnanthes aueri assemblages in more stagnant water. Weighted averaging and calibration were used to develop a statistical transfer function to infer the moisture content of moss samples from the diatom assemblages. Accepted: 29 March 1999     

Spatial and temporal variations in moss-inhabiting summer diatom communities from Potter Peninsula (King George Island, Antarctica)

This work represents the first analysis of the spatial and temporal variations in the diversity and community structure of diatoms associated with mosses, either dry or wet, sampled during the summer season from the littoral zone of three ponds in Potter Peninsula (King George Island, South Shetland Islands). It also seeks to explore the effect moisture content in the mosses can have on the structure of the diatom assemblages. The ponds approximately had the same number of species, and differences were found between the dry and wet sampling points. The same 4 species were predominant in the three ponds (Nitzschia alpina, N. perminuta, Staurosira oldenburgiana, and Pinnularia subantarctica var. elongata), but not in the same proportions. The first three species differed from those which were found to be dominant in other basins covered by mosses in southern South America and in the sub-Antarctic region. The latter, P. subantarctica var. elongata, had only been found to be abundant in a moss sample from another South Shetland Island. The diatom assemblages were found to be more strongly related to habitat traits (e.g. distance to the sea, ponds’ areas, and the vegetation’s moisture levels) than to the physical–chemical variables measured in the water.     

Is feeding on mosses by groundhoppers in the genus <Emphasis Type="Italic">Tetrix</Emphasis> (Insecta: Orthoptera) opportunistic or selective?

Groundhoppers are considered to be detrito-bryophagous, and moss phyllodes represent a main food consumed by all studied species. We studied the food biology of two groundhoppers: the stenotopic habitat specialist Tetrix ceperoi (Bolivar, 1887) and the eurytopic T. tenuicornis (Sahlberg, 1893). These species occurred syntopically in an abandoned sand pit in the Czech Republic. The dietary preferences of the two species were very similar, with detritus being the dominant component, followed by mosses and other kinds of organic matter. The eurytopic T. tenuicornis consumed a greater diversity of mosses than the stenotopic T. ceperoi. The most frequently consumed mosses were the dominant species at the locality (Barbula spp., Bryum caespiticium, and Ceratodon purpureus), but some species-specific preferences were evident in the consumption of other moss species. To determine whether these groundhoppers mainly consumed mosses to obtain the water in their tissues, we compared the food composition at two sites that differed considerably in water availability. A selective consumption of mosses according to the water availability at the sites was evident. At the dry site, groundhoppers frequently consumed mosses that are simultaneously more tolerant to desiccation and nutritionally richer (species in the genera Barbula and Ceratodon) than the other mosses. Our results indicate that although groundhoppers generally consume those mosses that are most available, they do show some preference for mosses according to their nutritional quality and according to their ability to retain water under dry conditions.     

海水来源的548株真菌的近海及远海分布模式及其抑菌活性分析

[目的]海洋真菌是新颖天然产物的理想来源.本研究旨在加深对可培养海洋真菌多样性的了解,以及挖掘具有应用潜力的海洋真菌.[方法]采用膜过滤法分离近海和远海海水样品中的真菌,通过菌株分离纯化、ITS基因序列测序,分析浅海带、半深海带和深海带海水样品中可培养真菌的多样性.在此基础上,采用固体平板法筛选具有抑菌活性的菌株.[结...     

Bryophytes as food: comparative consumption and utilization of mosses by a generalist insect herbivore

Compared with angiosperms, bryophytes are seldom fed upon by insects, despite being commonly used for shelter. Bryophytes are assumed to be unpalatable, and three classes of mechanisms have been suggested as possible barriers to bryophagy: chemical defenses, low digestibility, and low nutrient content. However, very few studies have tested these hypotheses. The present study examines pre‐ and post‐ingestive defenses of mosses. The acceptability and quality of four species of moss –Bryum argenteum Hedw. (Bryales: Bryaceae), Climacium americanum Brid. (Leucodontales: Climaciaceae), Leucobryum glaucum (Hedw.) (Dicranales: Leucobryaceae), and Sphagnum warnstorfii Russ. (Sphagnales: Sphagnaceae) – were compared with two control diets using the generalist caterpillar, Trichoplusia ni Hübner (Lepidoptera: Noctuidae: Plusiinae). In no‐choice trials, caterpillars consumed much less of any of the mosses than lettuce or wheat germ. The only moss consumed in sufficient quantities to evaluate post‐ingestive responses was C. americanum. Digestibility, assimilation, and overall utilization efficiency of C. americanum did not differ from that of lettuce, although C. americanum and lettuce were both less digestible than artificial diet. Choice assays using leaf discs showed that ethanol extract of L. glaucum, the least consumed moss, was deterrent, implying that chemical defenses play a major role in deterring feeding on L. glaucum. This study suggested that pre‐ingestive mechanisms are more important than post‐ingestive mechanisms in discouraging herbivory on mosses, and offered evidence that mosses are not simply nutrient poor.     

Studies of Aquatic Fungi. XVIII. Aquatic Fungi in Lake S̀niardwy and Eighteen Neighbouring Lakes

The work was undertaken to investigate the mycoflora of Lake S̀niardwy and eighteen adjacent lakes. Samples of water were collected once a month (1984-1987) for hydrochemical analysis and studies of the fungi content. Forty species of fungi were found in lake S̀niardwy and 60 in other lakes. The following fungi unknown from Poland were found in these lakes: Olpidium endogenum, Olpidium granulatum, Dictyomorpha dioica, Phlyctochytrium aureliae, Rhizophydium planktonicum, Zygorhizidium melosirae, Cladochytrium polystomum, Blastocladia rostrata, Olpidiopsis achlyae, Olpidiopsis pythii, Lagenidium rabenhorstii, Pythiella vernalis, Achlya rodrigueziana, Anguillospora gigantea, Dimorphospora foliicola and Mycocentrospora aquatica.     

AM真菌影响入侵植物黄顶菊与本土物种狗尾草竞争生长的机理研究

该研究以入侵植物黄顶菊[Flaveria bidentis(L.)Kunt]和本土伴生植物狗尾草为材料,通过筛选出黄顶菊单一优势群落AM真菌,于温室盆栽条件下,采用2物种单播、混播以及接种AM真菌和不接种共6个处理,分析AM真菌对黄顶菊和狗尾草的根系侵染率、相对竞争强度、植株氮磷钾光合利用率、以及丙二醛含量和保护酶活性的影响,探讨AM真菌对黄顶菊与狗尾草竞争生长的机理。结果显示:(1)黄顶菊根际土壤AM真菌共包括4属10种,其中优势种为Glomus constrictum、Glomus perpusillum、Glomus reticulatum;盆栽接种AM真菌后,黄顶菊的根系侵染率显著高于本土伴生植物狗尾草,但接种AM真菌后黄顶菊相对竞争强度显著降低了29.57%,却对狗尾草相对竞争强度无显著影响。(2)接种AM真菌使黄顶菊植株光合氮、磷、钾利用率显著升高,但对伴生植物狗尾草的光合氮、磷、钾利用率均无显著影响。(3)接种AM真菌对黄顶菊植株POD和CAT活性以及MDA含量无显著影响,但显著增加了SOD和APX活性,而伴对生植物狗尾草的POD、CAT和APX活性均显著降低,MDA含量显著提高。研究表明,AM真菌对黄顶菊和狗尾草具有不同的选择性,AM真菌的定植促进了黄顶菊的竞争生长,增加了植株N、P含量、光合养分利用率以及抗氧化酶活性;但显著降低了本土伴生植物狗尾草的N、P吸收以及抗氧化酶活性。因此,AM真菌在竞争生长中对黄顶菊产生了偏利反馈,有助于黄顶菊的入侵。     

Seasonal occurrence of water-borne fungi in Konaje stream (Mangalore), India

The Konaje stream near Mangalore University Campus has been surveyed during 1980–1981 for the occurrence of water-borne fungi by using three methods: leaf litter observations, foam analysis and water filtration. A total of twenty species of fungi has been recorded. Three species of fungi, Lunulospora curvula, Triscelophorus monosporus and Triscelophorus sp. were found to occur throughout the year. In all three methods Lunulospora curvula occurred in highest frequency. The occurrence of different species was found to correlate with the rainfall and leaf deposition in this region and not with water temperature.     

New Vice-County Records

Abstract

Bryophytes and vascular plants used in traditional home-made nativity sets were studied in an area of the Asturian Region, northern Spain. The results revealed a surprising plant diversity, with 66 bryophytes, three ferns and 37 flowering plants utilized. Most species, collected among more attractive mosses, were used only occasionally or accidentally, whereas only four large pleurocarpous mosses, Thuidium tamariscinum, Eurhynchium striatum, Hypnum cupressiforme and Pseudoscleropodium purum, were widely used, providing the moss base of all the sets. Additionally, eleven mosses and four native flowering plants were frequently selected. The diversity of the bryophytes used in nativity sets of different sizes is analysed, and the deliberate selection of moss species during the collecting is discussed. Finally, it is verified that the collection of certain showy mosses from forests and peat bogs could affect local populations of these mosses and entails the accidental removal of rare or endangered species.     

Studies on the aquatic hyphomycetes of a sulfur spring in the Western Ghats, India

Studies on the occurrence of aquatic hyphomycetes were carried out in Panekal sulfur spring in the Western Ghats, India by incubation of leaf litter and analysis of natural foam and of induced foam. Sampling was done once every three months over a period of two years from September 1989 to June 1991. The temperature, pH, dissolved oxygen, and sulfide content of water were also measured. No fungi were observed within the spring, whereas 16 species belonging to 13 genera were isolated from two outflow sites of the stream. The percent frequency of Triscelophorus monosporus was high (24.0%). The temperature of water in the spring ranged between 30.0 and 38.5°C and the sulfide content between 3.2 and 4.3 mg 1^–1. Studies showed that sulfide water (4.0 mg 1^–1). from the spring inhibited the growth of the colonies of Dactylella aquatica, Phalangispora constricta, Tetracladium setigerum, Vermispora cauveriana, and Wiesneriomyces laurinus. When the leaves colonized by aquatic hyphomycetes were incubated at different temperatures in sulfur-spring water and stream water separately, sporulation was not observed in any of the fungi at and above 35°C except Phalangispora constricta, which could sporulate at 35°C. At lower temperatures (15–30°C) relatively fewer species were found to sporulate in sulfur-spring water than in stream water. Correspondence to: K.M. Kaveriappa     

Photosynthetic traits of Sphagnum and feather moss species in undrained,drained and rewetted boreal spruce swamp forests

In restored peatlands, recovery of carbon assimilation by peat‐forming plants is a prerequisite for the recovery of ecosystem functioning. Restoration by rewetting may affect moss photosynthesis and respiration directly and/or through species successional turnover. To quantify the importance of the direct effects and the effects mediated by species change in boreal spruce swamp forests, we used a dual approach: (i) we measured successional changes in moss communities at 36 sites (nine undrained, nine drained, 18 rewetted) and (ii) photosynthetic properties of the dominant Sphagnum and feather mosses at nine of these sites (three undrained, three drained, three rewetted). Drainage and rewetting affected moss carbon assimilation mainly through species successional turnover. The species differed along a light‐adaptation gradient, which separated shade‐adapted feather mosses from Sphagnum mosses and Sphagnum girgensohnii from other Sphagna, and a productivity and moisture gradient, which separated Sphagnum riparium and Sphagnum girgensohnii from the less productive S. angustifolium, S. magellanicum and S. russowii. Undrained and drained sites harbored conservative, low‐production species: hummock‐Sphagna and feather mosses, respectively. Ditch creation and rewetting produced niches for species with opportunistic strategies and high carbon assimilation. The direct effects also caused higher photosynthetic productivity in ditches and in rewetted sites than in undrained and drained main sites.     

Ice formation in the freeze-tolerant eutardigrades Adorybiotus coronifer and Amphibolus nebulosus studied by differential scanning calorimetry

Summary This paper describes ice formation in two freeze-tolerant eutardigrades Adorybiotus coronifer and Amphibolus nebulosus, both commonly found in Arctic areas, based on a study by differential scanning calorimetry, and results are compared with similar investigations on freeze-tolerant insects. Under Arctic conditions A. coronifer typically inhabits drought-resistant mosses and overwinters in a frozen or dry state. A. nebulosus inhabits moist mosses or algae and overwinters as frozen cysts or, in few cases, as eggs or adults. Both species show a moderate capacity for supercooling, with crystallization temperatures (T_c) of -6° to -7°C. No differences in T_c were observed between summer- and winter-acclimatized A. coronifer or between active and encysted A. nebulosus. Distinct differences in the heat stability of their ice-nucleating activity indicate that the compounds responsible for nucleation are chemically different in the two species. Ice formation progresses rapidly in both species, and crystallization of water probably ceases within 1 min of the nucleation. Ice constitutes 80–90% of total body water, even at temperatures just below T_c, in both species. Winter-acclimatized A. coronifer build up about 10% less ice than summer-acclimatized animals, and a similar reduction was induced by cold-acclimation of summer animals in the laboratory. No winter reduction of the melting point could be detected in A. coronifer, indicating little, if any, accumulation of low molecular weight cryoprotectives. We suggest that the reduction in ice content is functionally related to increased amounts of water kept unfrozen due to interactions with macromolecules.