Bryophytes of the northern Yukon Territory,Canada, collected by A. J. Sharp and others

Two hundred and eight taxa of bryophytes, including two hundred and seven species, are reported from extreme northern Yukon. Five hepatic and eighteen moss taxa represent new records for the Yukon, which areAnastrophyllum hellerianum (Nees) Schust.,Scapania degenii Schiffn. in K. Müll.,Riccardia palmata (Hedw.) Carruth.,Mannia sibirica (K. Müll.) Frye & Clark,Sauteria alpina (Nees) Nees,Sphagnum orientale Savich,Dicranum spadiceum Zett.,Anoectangium aestivum (Hedw.) Mitt.,Barbula coreensis (Card.) Saito,B. platyneura C. Müll. & Kindb.,Pottia obtusifolia C. Müll.,Splachnum vasculosum Hedw.,Bryum acutiforme Limpr. ex Hag.,B. bimum (Brid.) Turn.,B. intermedium (Brid.) Bland.,B. neodamense Itzigs.,Cinclidium latifolium Lindb.,Timmia comata Lindb. & Arn.,Orthothecium acuminatum Bryhn,Cratoneuron arcticum Steere,Drepanocladus brevifolius (Lindb.) Warnst.,D. intermedius (Lindb.) Warnst., andD. lycopodioides (Brid.) Warnst. Many of the other collections represent significant extensions of ranges to the arctic sector of the Yukon Territory.     

柳叶藓科2种1变种在中国的新记录

笔者在编研(中国苔藓志》第七卷的过程中,发现柳叶藓科中的圆叶湿原藓Calliergon megalophyl- lum Mikut．、毛叶镰刀藓 Drepanocladus trichophyllus (Warnst．)Podp．和牛角藓宽肋变种Cratoneuron filicinum (Hedw．)Spruce var．atro-virens (Brid．)Ochyra为中国首次记录,而沼生湿柳藓 Hygroamblystegium noterophi-lum (Sull．et Lesq．)Warnst．属错误鉴定,所有以前被定为该种的中国标本应改为牛角藓宽肋变种。     

Photosynthetic response of the Antarctic moss Polytrichum alpestre Hoppe to low temperatures and freeze-thaw stress

The effect of low temperatures and freeze-thaw stress on photosynthetic carbon exchange in an Antarctic population of the turf-forming moss species Polytrichum alpestre Hoppe was investigated using infra-red gas analysis. Photosynthetic recovery from freezing was found to depend on the absolute depth of low temperature experienced. Repeated freeze-thaw cycles caused a greater reduction in gross photosynthesis than constant freezing over the same period of time suggesting that the freeze-thaw event itself, and not just cold temperatures, causes damage. The frequency of freeze-thaw events was significant: freeze-thaw cycles every 12 h inflicted more damage than freezethaw cycles every 24 or 48 h. Most damage occurred during the first cycle; relatively little was recorded during subsequent cycles. At +10°C, gross CO₂ flux was directly proportional to moss water content between 0.3 and 3.5 g·g^–1 dry mass. Moss samples with a low water content withstood freeze-thaw cycles to -5, -10 and-20°C better than samples with a high water content indicating that desiccation in the field may improve survival at low temperatures. Microclimate data for field populations of Polytrichum alpestre at Signy Island suggest that sub-zero temperatures and freeze-thaw stress may act as limiting factors on the species' distribution and viability, particularly when the insulating effect of snow cover is small.     

Two species and one variety of the Amblystegiaceae (Musci) new to China

During our recent study of the Chinese Amblystegiaceae, we found that Calliergon megalophyllum Mikut., Drepanocladus trichophyllus (Warnst.) Podp. and Cratoneuron filicinum (Hedw.) Spruce var. atro-virens (Brid.) Ochyra are new to China. The occurrance of Hygroumblystegium noterophilum (Sull. et Lesq. ) Warnst. in China as previously recorded represents only a misidentification. All the Chinese specimens referred to this species should be identified as Crato-neuron filicinum (Hedw.) Spruce var. atro-virens (Brid.) Ochyra.     

Physiological Effects of Heavy Metals on the Moss Rhytidiadelphus squarrosus

Experiments on the effect of Cd, Cu, Ni, Pb and Zn, suppliedas single salt solutions between 10 µM and 0·1M, on the moss Rhytidiadelphus squarrosus showed little alterationto respiratory rates but reduced photosynthetic rates, and somemembrane damage as assessed by K leakage. Two distinct morphologicalforms of the moss showed different responses to supplied heavymetal. Storage of material, after 30 mins exposure to heavymetals, resulted in a further decrease in the photosyntheticrate. Expressing the photosynthetic decline relative to thetotal heavy metal recovered from the moss showed a similar pattern.Transfer of metal from extracellular exchange sites into theprotoplast was also demonstrated with storage after exposure.An approximately linear relationship was demonstrated betweenphotosynthetic decline and intracellular heavy-metal concentration,irrespective of the duration of exposure or morphological natureof the material used. Photosynthetic decline on storage is concludedto be a response to additional metal stress rather than a progressivedeterioration of the physiological process. Cadmium, copper, lead, nickel, zinc, photosynthesis, respiration, membrane damage, intracellular metals, Rhytidiadelphus squarrosus (Hedw.) Warnst     

Moss production in a black spruce Picea mariana forest with permafrost near Fairbanks,Alaska, as compared with two permafrost-free stands

During the 1975 and 1976 seasons the net primary production of five common bryophytes in different stands of mature vegetation near Fairbanks, Alaska was investigated. Overall annual moss production at the intensive black spruce site was about 120 g m^?1 yr^?1 or about twice as high as the corresponding annual spruce production. Maximum rates of net photosynthesis varied from 2.7 mg CO₂ g^?1 h^?1 in Polytrichum commune Hedw. to 0.6 mg CO₂ g^?1 h^?1 in Sphagnum nemoreum Scop. The photosynthesis of overwintered leaves early in the season was low and as a result of new growth a steady increase in net photosynthesis occurred throughout the season. Leaf water content was found to be the most important limiting factor for growth under natural conditions. There was a strong increase in growth and photosynthesis of Sphagnum nemoreum after application of N and P, indicating nutrient deficiency.     

The identity of the Pleistocene mosses Drepanocladus minnesotensis and Neocalliergon integrifolium (Amblystegiaceae)

The type specimens ofDrepanocladus minnesotensis Williams andNeocalliergon integrifolium Williams are shown to beD. aduncus var.kneiffii (B.S.G.) Monk. andScorpidium scorpioides (Hedw.) Limpr., respectively. These fossils, which were originally obtained from late glacial sediments in Minneapolis, Minnesota, together with other mosses identified from the deposit, indicate that deposition probably took place in a shallow depression filled with calcareous water. Pleistocene mosses from near Bronson, Minnesota, originally namedD. minnesotensis are reidentified asD. aduncus (Hedw.) Warnst. andCalliergon giganteum (Schimp.) Kindb.     

Iron accumulation on the cell wall of the aquatic moss Drepanocladus fluitans in an acid lake at pH 3.4–3.8

Iron accumulation was studied in shoots of the aquatic moss Drepanocladus fluitans (Hedw.) Warnst collected from an acid lake and stream. The concentration of iron in the shoots of the moss from Lake Usoriko (pH 3.4–3.8) increased from the tip toward the base and ranged from 0.07 to 10% on a dry weight basis. The iron concentration in the lake water was 0.15 mg 1^–1. In contrast, iron concentration in the shoots of D. fluitans from Kashiranashigawa stream (pH 4.2–4.7), one of the streams flowing into Lake Usoriko, was only 0.02 mg g^–1 at the shoot tip and 0.3% at the shoot base, while that in the stream water was <0.02 mg 1^–1. Transmission electron microscopy using a X-ray microanalyzer (TEM-XMA) study revealed accumulation of needle-like iron crystals on the cell wall and decomposed cell components. In addition, many rod-type bacteria were found in the accumulated iron deposits.The accumulation of iron in the shoots of D. fluitans is due to two processes: biological accumulation of essential iron dissolved in acid water, and abiological crystal growth on the surface of organic particulate material including the cell wall.     

Bryophytes from the southeastern Yukon Territory,Canada

One hundred and forty-five taxa of bryophytes are reported from the extreme southeastern Yukon. Eight species of Hepaticae and 13 of mosses represent new records for the Yukon, which are Calypogeia suecica (S. Arnell & Perss.) K. Müll., Chiloscyphus pallescens (Ehrh.) Dum., Conocephalum conicum (L.) Dum., Jamesoniella autumnalis (DC.) Steph., Pellia neesiana (Gott.) Limpr., Ptilidium pulcherrimum (Web.) Hampe, Riccardia palmata (Hedw.) Carruth., Tritomaria exsecta (Schmid.) Schiffn., Amblystegium varium (Hedw.) Lindb., Brachythecium rivulare B.S.G., B. rutabulum (Hedw.) B.S.G., Bryum blindii B.S.G., Didymodon rigidulus Hedw., D. tophaceus (Brid.) Lisa, Drepanocladus trichophyllus (Warnst.) Podp., Hygroamblystegium noterophilum (Sull. & Lesq. ex Sull.) Warnst., Hygrohypnum molle (Hedw.) Loeske, Plagiomnium ciliare (C. Müll.) Kop., P. cuspidatum (Hedw.) Kop., Platydictya minutissimum (Sull. & Lesq. ex Sull.) Crum, and Pylaisiella selwynii (Kindb.) Crum, Steere & Anderson. Many of the other collections represent wide extensions of range within the Yukon Territory.     

Chlorophyll Fluorescence during Drying and Rehydration in the Mosses Rhytidiadelphus loreus (Hedw.) Warnst.,Anomodon viticulosus (Hedw.) Hook. & Tayl. and Grimmia pulvinata (Hedw.) Sm.

Chlorophyll-fluorescence parameters of three mosses, Rhytidiadelphusloreus (Hedw.) Warnst.,Anomodon viticulosus (Hedw.) Hook &Tayl. and Grimmia pulvinata (Hedw.) Sm. were measured duringdrying, and following remoistening after a period of desiccation.Most changed little with drying until the full-turgor pointwas approached, when rapid changes accompanied loss of cellwater. In R. loreus all parameters decreased together down toa water content of about 30% d.wt (RWC approx. 0.15). At lowwater contents (5–16% d.wt; RWC approx. 0.02–0.08)saturating pulses tended to suppress rather than stimulate fluorescence.In A. viticulosus F_v/F_m, q_Pand     

Environmental factors influencing decomposition rates in two Antarctic moss communities

Summary Rates of disappearance of dead material of Polytrichum alpestre and Chorisodontium aciphyllum from a moss turf community and of Drepanocladus uncinatus, Calliergon sarmentosum and Cephaloziella varians from a moss carpet community, measured using litter bags over 2 years, were 1.5% year^-1. Decomposition potential, estimated using loss in tensile strength of cotton strips inserted into the different bryophytes on the two sites, was also low. Ranking the five plant species in order of decomposition potential, from highest to lowest, gave D. uncinatus, C. aciphyllum, C. sarmentosum, P. alpestre and C. varians. The time taken for the tensile strength of the cotton strips at depths of 1–3 and 4–6 cm beneath the surface to decline by 50% varied from 1–2 years under the first two species to 3–4 years beneath the last two species. The main causes of these slow rates were low temperatures, short active season and low pH. Differences in decomposition between species, sites and with depth were related to temperature, nutrient status, water content and anaerobic conditions. Variation in anaerobic conditions beneath D. uncinatus, C. sarmentosum and C. varians in the moss carpet resulted in wide variation of decomposition rate beneath these species and with depth beneath C. varians. The peat in the moss turf was aerobic and experienced higher temperatures, but the average decomposition rate was no higher than in the moss carpet, because the peat was of a poorer quality and had a lower pH.     

Moss functioning in different taiga ecosystems in interior Alaska

Summary Carbon dioxide exchange rates in excised 2-year-old shoot sections of five common moss species were measured by infrared gas analysis in mosses collected from different stands of mature vegetation near Fairbanks, Alaska. The maximum rates of net photosynthesis ranged from 2.65 mg CO₂ g^-1h^-1 in Polytrichum commune Hedw. to 0.25 in Spagnum nemoreum Scop. Intermediate values were found in Sphagnum subsecundum Nees., Hylocomium splendens (Hedw.) B.S.G., and Pleurozium schreberi (Brid.) Mitt. Dark respiration rates at 15°C ranged from 0.24 mg CO₂ g^-1h^-1 in S. subsecundum to 0.57 mg CO₂ g^-1h^-1 in H. splendens. The dark respiration rates were found to increase in periods of growth or restoration of tissue (i.e., after desiccation). There was a strong decrease in the rates of net photosynthesis during the winter and after long periods of desiccation.Due to increasing amounts of young, photosynthetically active tissue there was a gradual increase in the rates of net photosynthesis during the season to maximum values in late August. As an apparent result of constant respiration rates and increasing gross photosynthetic rates, the optimum temperature for photosynthesis at light saturation and field capacity increased during the season in all species except Polytrichum, with a corresponding drop in the compensation light intensities. Sphagnum subsecundum seemed to be the most light-dependent species.Leaf water content was found to be an important limiting factor for photosynthesis in the field. A comparison between sites showed that the maximum rates of net photosynthesis increased with increasing nutrient content in the soil but at the permafrostfree sites photosynthesis was inhibited by frequent moisture stress.     

Observations on Chromosomes of Fourteen Moss Species from the Qinling Range,China

The chromosome numbers in fourteen moss species from the Qinling Range, and karyotype of Mnium lycopodioides are reported in this paper. Immature capsules were used as material. Bryum capillare L. ex Hedw was found. to have n = 10; Mnium lycopodioides Schwaegr. n = 6 with the karyotype formula n = 6 = 3m+3sm (1SAT); Plagiomnium maximoviczii (Lindl.)T. Kop. n=6; Bartramia halleriana var. elongate Turn. n=10+2m; Thuidium delicatulum (Hedw.) Mitt. n= 11; Thuidium philibertii Limpr. n= 10+m; Hygrohypnum ochraceum (Wils.) Loesk. n=10; Drepanocladus uncinatus (Hedw.) Warnst. n = 7+3m; Campylium chrysophyllus (Brid.) J. Lange. n = 10; Brachythecium starkei (Brid.) B. S. G. n=6; Brachythecium buchananii (Hook.) Jaeg. n=6; Brotherella yokohamae (Broth.)Broth. n= 9+2m; Gollamia neckerella (C. MÜll. )Broth. N=7; Pogonatum fastigiatum Mitt. n = 7. No report on the chromosome number of Brotherella yokohamae and Gollania neckerella has been found. The chromosome numbers in Brachythecium starkei andBrachythecium buchananii (Hook.) Jaeg. are different from previous reports, while the others are in accordance with the previous reports.     

Green light drives photosynthesis in mosses

Temperate forests are characterised by variable light quality (i.e. spectral composition of light) at or near the forest floor. These understory environments have a high concentration of green light, as red and blue light are preferentially absorbed by upper canopy leaves. Understory species may be well-adapted for using green light to drive photosynthesis. Angiosperms have been shown to use green light for photosynthesis, but this ability has not been demonstrated in shade-dwelling bryophytes. In this study, net photosynthetic rate (P_N) of three temperate understory species of moss (Dichodontium pellucidum (Hedw.) Schimp., Leucobryum albidum (Brid. ex P.Beauv) Lindb. and Amblystegium serpens (Hedw.) Schimp.) was measured under green, red?+?blue, and red?+?blue?+?green light to assess green light use efficiency. All three species were capable of photosynthesising beyond their respiratory demands using solely green light, with higher green light use efficiency measured in plants collected from areas with greater canopy cover, suggesting growth in a green light concentrated environment increases green light use efficiency. Each species was also collected from sites differing in their degree of canopy cover and grown under three light treatments (high light, low light, and green light). Photosynthetic efficiency (chlorophyll fluorescence), tissue nitrogen and carbon isotope concentrations were assessed after a short growth period. Growth conditions had little effect on leaf chemistry and monochromatic green light did not significantly degrade photosynthetic efficiency. This study provides the first evidence to date of positive net ‘green light photosynthesis’ in mosses.     

Distribution of carbon,nitrogen and phosphorus in a moss community-soil system developed on a cold desert in Antarctica

The distributions of carbon, nitrogen and phosphorus in a moss community-soil system developed on a naked region in Rundvågskollane (69⁰50'S, 39⁰09'E), East Antarctica, were investigated in order to analyze the flow of matter in an Antarctic terrestrial ecosystem.

1. The moss community was formed from many moss blocks of different sizes and was composed ofBryum pseudotriquetrum (Hedw.) Gaertn., Meyer et Scherb.,Ceratodon purpureus (Hedw.) Brid. andGrimmia lawiana J. H. Willis. The surface of the community was covered with cyanobacteria.
2. It was estimated that nitrogen fixed by cyanobacteria flowed from these organisms to the moss and that little nitrogen was transported within the moss body.
3. A large amount of phosphorus existed in the soil. The moss community had a high phosphorus content although the amount itself was relatively little due to the small phytomass.
4. It seems that absorption of phosphorus from soil is difficult for moss, because of the paucity of water necessary for the movement of phosphorus and the suppressed growth of moss due to the arid conditions.

     

<Emphasis Type="Italic">Drepanocladus longifolius</Emphasis> (Amblystegiaceae), an addition to the moss flora of King George Island,South Shetland Islands,with a review of Antarctic benthic mosses

Drepanocladus longifolius (Mitt.) Paris is recorded for the first time from King George Island, South Shetland Islands, in the maritime Antarctic. It was collected in West Lake during the 23rd Chinese National Antarctic Research Expedition in 2006–2007. The moss was found at a depth of 5–6 m attached to the bed of the lake. The stems of the moss are about 1–1.5 m in length. The moss exhibits seasonal growth patterns, with shorter branch internodes, more widely spaced leaves and more branches in summer than in winter. Most of the branches are initiated in summer. The annual shoot extension is about 3–6 cm, which implies that the plants must be at least 15 years of age. The distribution of aquatic moss species and records in Antarctica is outlined and discussed and the nomenclature of previous reports clarified.     

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.

     

Soil cations influence bryophyte susceptibility to bisulfite

The hypothesis that metal ions absorbed by bryophytes from the underlying soil may ameliorate adverse effects of SO2 was investigated in the terricolous moss species Pleurozium schreberi (Brid.) Mitt. and Rhytidiadelphus triquetrus (Hedw.) Warnst. Dilute sodium bisulfite solutions (equivalent to dissolved SO2) were applied to shoots isolated from soil or in contact with artificial substrata. Marked inhibition of net photosynthesis was observed within 2 h of treatment with 0.3 mM bisulfite in both mosses. Progressive recovery of net photosynthesis occurred 2-8 h after bisulfite treatment, although the extent of this depended on the concentration and pH of the solution. When R. triquetrus and P. schreberi were grown on artificial substrata (calcareous, acid-mineral or acid-organic) with weekly bisulfite applications, the only significant effect was poorer growth of P. schreberi receiving bisulfite on the calcareous and acid-organic substrata. In both species, growth on the calcareous substratum led to increased concentrations of exchangeable Ca2+, whereas exchangeable Fe3+ concentrations increased following growth on the acid-mineral soil. In another experiment the two mosses were pre-treated with either Ca2+ or Fe3+ before incubation with bisulfite. In P. schreberi, the depression of net photosynthetic rate caused by bisulfite was ameliorated from 33 to 64% of the control by pre-treatment with Fe3+, but it was unaffected by Ca2+ pre-treatment. In R. triquetrus, the amelioration caused by Fe3+ pre-treatment was from 16 to 60% of the control, but pre-treatment with Ca2+ gave a greater amelioration, to 75% of the control value. The responses are discussed in terms of soil preferences of the mosses and possible underlying bisulfite amelioration mechanisms.     

Effects of Intermittent Desiccation on Nutrient Economy and Growth of Two Ecologically Contrasted Mosses

The mossesBrachythecium rutabulum (Hedw.) B., S. & G. andPseudoscleropodiumpurum (Hedw.) Fleisch. were cultivated for more than 50 d ina growth cabinet with or without weekly drying interludes of24 h. Some plants also received applications of a dilute NPKnutrient solution at weekly intervals. The continuously hydratedplants showed appreciably more biomass production than thosereceiving intermittent desiccation. Desiccation led to somebleaching of the green tissues inB. rutabulum but not inP. purumwhich appeared more desiccation-tolerant. NPK addition causeda further significant growth stimulation in continuously hydratedplants, but not in intermittently desiccatedB. rutabulum. Pseudoscleropodiumpurum showed NPK-induced growth stimulation even when intermittentlydesiccated. Net uptake of N was similar in desiccated and hydratedplants in both species. Considerable net uptake of P and K⁺occurredin continuously wetB. rutabulum , but uptake was much reducedin intermittently desiccated plants. Net uptake of P and K⁺byP.purum was similar in desiccated and hydrated samples. IntracellularK⁺, leaked from the cells during the desiccation treatment,was retained by cation exchange on the negatively charged cellwalls in both species. Levels of intracellular K⁺and Mg²⁺inthe new growth were maintained at the expense of the pool ofexchangeable cations. The growth stimulation and the net uptakeof nutrients under intermittent desiccation was greatest whenthe NPK application was made at the start of rehydration, possiblybecause of accentuated uptake in the early stages of recovery.The results support the hypothesis thatP. purum has a lowernutrient requirement thanB. rutabulum and highlight the importanceof continuous hydration for the latter's more productive plantlife strategy. The data also show that considerable new growthof bryophyte tissues is possible without additional nutrientabsorption. Brachythecium rutabulum ; Pseudoscleropodium purum ; mineral nutrition; desiccation; solute leakage; plant life strategies     

Observations of spore morphology of some Pottiaceae Schimp. species (Bryophyta) in Turkey

The spores of Syntrichia ruralis (Hedw.) F. Weber and D. Mohr., S. princeps (De Not.) Mitt., S. subulata (Hedw.) F.Weber and D.Mohr var. subulata, S. subulata (Hedw.) F.Weber and D.Mohr var. angustata (Schimp.) J.J. Amann and S. subulata (Hedw.) F.Weber and D.Mohr var. graeffii Warnst. were studied by light and scanning electron microscopy for the first time. The apertural region consists of a leptoma in all spores. All taxa of the family are uniform in their spore morphology. The spores of the five taxa are of granuloid type. The spore wall of the Pottiaceae family includes sclerine (the distinction between exine and perine may be difficult to define) and intine. The taxonomy of the genus Syntrichia is discussed on the basis of its spore morphology.