Studies on the Sporogenous Lineage in the Moss Timmiella barbuloides

This correlated immunofluorescence and electron microscope study reveals that the microtubule arrays during meiosis in Timmiella barbuloides mirror those in other mosses but the organization of the metaphase I spindle is quite different. In other mosses the sagittiform metaphase I spindle initially contains four bands of microtubules derived from the tetrahedral system present at prophase. These bands converge towards the division axis and each half spindle contains two focal points of microtubules straddling a cleavage furrow. In Timmiella the sagittiform spindle also contains four microtubular foci derived from the preprophasic tetrahedron. However, one of these contributes to one half spindle, the other half deriving from the three remaining foci orientated at approximately 120° to each other. In contrast to other mosses the sporocytes in Timmiella are hardly lobed, the cleavage-furrows ill-defined, the prophasic plastid positioning in the lobes is also more variable and the organelle band in meiocytes comprises mitochondria alone.     

Measurement uncertainty from physical sample preparation of moss samples: Estimation of mechanical cleaning vs. rinsing

Next to sampling, the physical sample preparation step is a second large source of uncertainty. To assess the level of uncertainty from sampling, sample preparation and analysis of moss material, 27 combined and duplicate samples of moss species Pleurozium schreberi (Brid.) Mitt were collected and prepared for analysis using two different treatment methods After sampling had been done, samples were dried at an ambient temperature and then each primary and duplicate sample was divided into two sub-samples for preparation. The first sub-sample was manually cleaned whereas the second one was triple rinsed with deionized water and left to dry. Subsequently, the samples were milled and digested in a close microwave system with 8 mL of HNO₃ (1:1) and 1 mL of 30% H₂O₂. In all samples Cu, Fe and Zn were determined using GFAAS and FAAS techniques. Each sample was analyzed twice. Sampling, sample preparation and analytical uncertainty were calculated using ANOVA, RANOVA, modified RANOVA and range statistics methods. Sampling and sample preparation uncertainty varied from 3.8 to 19.8% and from 3.6 to 11.2%, respectively. For all the elements examined analytical uncertainty was below 1.1%. The comparison of element concentrations in manually cleaned and rinsed samples showed that rinsed samples were enriched in Cu and Zn, as opposed to manually cleaned that in turn displayed raised levels of Fe. However, except for Zn, these differences were not statistically significant.     

Biodiversity Hotspots from a Multigroup Perspective: Mosses and Senecios in the Transmexican Volcanic Belt

Geographical information for 703 mosses and Senecios (species of the tribe Senecioneae, Asteraceae) has been analyzed to identify patterns of species richness in the Transmexican Volcanic Belt (TMVB) of Mexico. Because the TMVB holds a high proportion of these taxa (596 mosses out of 980, and 107 Senecios out of 228) in the country, it is considered a high diversity area. However, the biodiversity is not uniform, as shown by the number of species in each of seventy nine 0.5° latitude and 0.5° longitude cells covering the surface area of the mountain range. Nineteen cells were identified as hotspots and further analysis showed that 11 of such hotspots were common to both groups. The application of a heuristic iterative method and a complementarity criterion indicated that the selection of 18 cells would conserve the total diversity of mosses and Senecios found in such hotspots.     

The top of the Pollino massif (southern Italy), an important refuge area for noteworthy mosses

The occurrence on the Pollino massif (southern Italy) of several remarkable mosses, which are rare or very rare in Italy, is reported. They are Orthotrichum acuminatum H. Philib., Distichium inclinatum (Hedw.) Bruch & Schimp. and Grimmia longirostris Hook., new to the southern part of the Italian peninsula, and Schistidium dupretii (Thér.) W.A. Weber, new to South Italy. Moreover, Orthotrichum cupulatum Hoffm. ex Brid. var. fuscum (Venturi) Boulay, a very rare taxon in Europe and up to now considered vanished in Italy, is rediscovered in Italy after about one century from its single previous report.     

Additional reports for Italian moss flora

As a result of the study of both recent collections and a review of herbarium specimens, the following taxa are reported for the first time from various Italian regions: Hedwigia stellata Hedenäs, Hedwigia ciliata var. leucophaea Bruch & Schimp., Pleurozium schreberi (Willd. ex Brid.) Mitt. and Ptychostomum compactum Hornsch. var. compactum. The last taxon is new for southern Italy, while the report of Pleurozium schreberi confirms the occurrence of this species in southern Italy after more than half a century. Moreover, Crossidium laxefilamentosum Frey & Kürschner represents the second report of this species from Italy.     

On the influence of water conductivity,pH and climate on bryophyte assemblages in Catalan semi-natural springs

Bryophytes are some of the most sensitive biological indicators of environmental change. Springs have a significant presence of bryophytes and so are ideal habitats for studying their relationship with the environment. We tested whether bryophyte assemblages can be explained with macro-, meso- and micro-ecological variables (i.e. seasonal climate, altitude, water pH and conductivity) sampling bryophytes from 198 semi-natural springs distributed along montane regions in the north-eastern Iberian Peninsula. We tested the influence of environmental variables on bryophyte assemblages in springs using sparse Partial Least Squares. Our results show that variability in bryophyte assemblages is explained by seasonal climate (temperature and precipitation from winter, spring, summer and autumn and temperature and precipitation seasonality), altitude and water conductivity. The results obtained by the present study will be useful for predicting bryophyte diversity in springs using simple and easy to obtain variables such as climate, water pH and conductivity.     

3种藓类植物水分含量与光合作用、呼吸作用和水势的关系

对湿地匍灯藓〔Plagiomniumacutum(Lindb.)T.Kop.〕、大羽藓〔Thuidiumcymbifolium(Dozy&Molk.)Dozy&Molk.〕和垂藓〔Chrysocladiunretrorsum(Mitt.)Fleisch.〕的水分含量与光合作用、呼吸作用和水势的关系进行了初步研究（1999年5月20日到6月10日）。在这3种藓类植物中,其水分含量与光合作用速率（Pn）的关系可以分为2种类型一种类型如大羽藓和垂藓,在藓体水分含量20%～70%时,Pn随着水分含量增加而增加,但是在80%～95%时,Pn随水分含量增加而下降,光合最适水分含量约70%～80%;另一种出现在湿地匍灯藓,水分含量20%～80%时,Pn随着水分含量增加而增加,在80%～95%时,Pn维持一个较高的水平,光合最适水分含量为80%～90%。在一个大的水分含量范围内（60%～95%）,暗呼吸（Rd）保持相对稳定,但是在水分含量较低时（20%～70%）,Rd随着水分含量的下降而下降。在藓体水分含量与水势之间的关系方面,3种藓类植物相似,水分含量与水势对数之间的回归曲线为S形曲线。     

Patterns of desiccation tolerance and recovery in bryophytes

The study of desiccation tolerance in bryophytes avoids thecomplications of higher-plant vascular systems and complex leaf structures, butremains a multifaceted problem. Some of the pertinent questions have at leastpartial analogues in seed biology – events during a drying-rewettingcyclewith processes in seed maturation and germination, and the gradual loss ofviability on prolonged desiccation, and the relation of this to intensity ofdesiccation and temperature, with parallel questions in seed storage. Pastresearch on bryophyte desiccation tolerance is briefly reviewed. Evidence ispresented from chlorophyll-fluorescence measurements and experiments withmetabolic inhibitors that recovery of photosynthesis in bryophytes followingdesiccation depends mainly on rapid reactivation of pre-existing structures andinvolves only limited de novo protein synthesis. Followinginitial recovery, protein synthesis is demonstrably essential to themaintenanceof photosynthetic function in the light, but the rate of maintenance turnoverinthe dark appears to be slow. Factors leading to long-term desiccation damagearediverse; indications are that desiccation tolerant species often survive bestinthe range –100 to –200 MPa.     

广东石门台自然保护区藓类植物初报

石门台自然保护区位于广东省中北部,面积82260hm^2,是全省面积最大的保护区。根据我们过去三年的初步调查和研究,石门台保护区共有藓类植物33科89属158种(含1亚种3变种),其中广东新记录属3属,分别是Eccremidium、Phyllodon和Stereodontopsis;另外,Eccremidium brisbanicum等23种为广东新记录种。