Distribution quantified by microtopography in an assemblage of saxicolous mosses

Microtopography was quantified and related to plant microdistribution in an assemblage of bryophytes on granitic rocks in the inland chaparral of San Diego County, California, U.S.A. The dominant species, Grimmia laevigata, grew mostly on north-, east-, and west-facing surfaces with slope less than 60°. Other bryophytes tended to grow on steep, concave, north- and west-facing surfaces. Occurrence of these latter species was strongly associated with shade, as estimated from microtopography. The relationship of microdistribution to microclimate and ultimately to plant physiology can probably be successfully defined in systems such as this.Nomenclature follows Crum et al. (1973) for bryophytes and Munz (1974) for vascular plants.I thank W. C. Oechel for arranging access to the San Diego State University research area at Echo Valley and to facilities maintained there by the Systems Ecology Research Group; D. Alpert, C. Harkins, C. M. M. Hermida, J. Jacobson, and C. Scheidlinger for assistance with portions of the field work; M. P. Harthill and B. D. Mishler for help with identification of mosses; H. A. Mooney for comments on an earlier draft; and R. E. Cook and N. G. Miller for advice and support in many forms. This work was supported by National Science Foundation Grant DEB-7906428 and by a grant from the William and Alice Hinckley Scholarship Fund.     

The consensus land plant chloroplast gene order is present, with two alterations, in the moss Physcomitrella patens

Summary A restriction endonuclease cleavage site map for the enzymes ClaI and BglII, and a partial map for SacI, has been constructed for the chloroplast genome of the moss Physcomitrella patens (Hedw.) BSG. The plastid chromosome contains approximately 122 kb organized into small (21 kb) and large (82 kb) single-copy regions separated by two copies of a repeat sequence (9.4 kb) oriented in an inverted arrangement. Genes for 17 proteins and 2 ribosomal RNAs have been mapped using heterologous probes from corn, spinach, pea, and petunia. The general order and arrangement of the moss chloroplast genes are similar to the consensus land plant genome typified by that of spinach, with two major exceptions. First, there is an inversion of approximately 20 kb, bordered internally by psbA and atpH, and also containing the genes atpF and atpA. Second, rpl2 and rps19 have been relocated to a different position within the large single-copy region, adjacent to the 20 kb inversion.     

Monitoring of pollen rain in moss polsters and mats in view of their suitability as controls for determining the air-borne component of pollen spectra in herbivore faeces

Pollen has been extracted from six bryophyte and two lichen taxa, sampled from three habitats: upland heath, lowland bog and mixed woodland, in both west and east Scotland. The highest number of pollen taxa was recorded in bothSphagnum andThuidium; the lowest numbers of pollen taxa were recorded in two of the mosses and both lichens. For pollen rain control purposes in herbivore faecal studies, woodland species of bryophytes are not suitable due to the sheltering effects from rain provided by the overhead canopy. Open habitats such as moorland heath and bog provide polsters/mats which normally trap pollen rain more effectively for control purposes. The aim of this study was twofold: to observe the effectiveness of selected polsters and lichens as traps for pollen rain and to establish eventually, whether or not such vegetative traps could be used as controls in pollen spectra analyses of herbivore faeces for the determination of nutritional regime and habitat. From a comparison with recent studies in north west Spain of three taxa in common with Scottish samples,Polytrichum demonstrated a consistently higher number of pollen taxa trapped.Thuidium andCladonia all yielded between one and a half and three times the number of pollen taxa as in the same three bryophyte/lichen taxa sampled in Scotland. Investigation relating the pollen rain trapped in polsters to that in faecal material are continuing, and will be reported in due course.This paper is based on one given by E.C. at the 5th International Aerobiology Conference, held at Bangalore, India, August 1994.     

Influences of neighbouring plants on seedling establishment in limestone grassland

Abstract. Influences of neighbouring plants on seedling establishment of six dicotyledonous species was investigated in a nutrient-poor limestone grassland (Mesobrometum) in northern Switzerland. Microsites with different vegetational structure were created and seeds sown in them. The fate of emerging seedlings was followed for one or two years. A plant surviving its first growing season was regarded as established. Shelter by neighbouring plants appeared to be necessary for the establishment of Arabis hirsuta and Primula veris. Because of drought and frost heave, hardly any seedlings of these species established in gaps (4 - 21 %). In microsites with vegetation, their survival was significantly higher (40–57 %). Neighbouring plants slightly reduced the survival of Plantago lanceolata and Sanguisorba minor, but these species established well both in gaps (74 - 81 %) and in vegetated microsites (54 - 67 %). Medicago lupulina established well in all microsites in one year (71 - 79 %), but poorly in the next year (18–32 %). Linum catharticum emerged poorly in one year and was completely extinguished by a fungal pathogen the following year. The overall conclusion is, that gaps are of minor importance for recruitment of these species in this grassland. Physical hazards and pathogens control seedling establishment to a greater extent than competition by neighbouring plants. Some species are hardly able to establish without shelter of vegetation. Seed size is an important factor for success of establishment, especially in gaps. It is suggested, that the relatively low productivity and the absence of litter accumulation (due to mowing and biomass removal) are important conditions for the observed behaviour of the seedlings and juvenile plants in this community.     

北京小龙门自然保护区四种苔藓鸟巢的观察

2004年8月20～22日在北京小龙门自然保护区,分别对宝兴歌鸫（Turdus mupinensis）、黄眉姬鹪（Ficedula narcissina）、白腹蓝鸫（Cyanoptila cyanomelana）和北红尾鸲（Phoenicurusauroreus）4种鸟的鸟巢的结构和巢材进行了观察,发现他们均用藓类植物作为巢材。经过鉴定,这些藓类植物共7种,分属于4科,其中最多是小牛舌藓（Anomodon minor）。该文还对巢材中藓类植物的分布、生物学特性和鸟类取材的行为等进行了初步分析。     

The coarse‐root system of mature Populus tremuloides in declining stands in Alberta,Canada

Abstract. The coarse‐root dynamics of ramets of Populus tremuloides (aspen) were investigated with respect to persistence of the original root connections (roots of parent trees from which the ramets originated), the time of establishment of new roots at the base of the stem and the fate of the communal root system after death of individual trees. Parts of the root systems of three declining stands of aspen ramets were hydraulically excavated. From each stand, sections of all structural roots were collected at the base of live and dead trees and were analysed using dendrochronology techniques. Parent roots were identified in the root system of every tree. The trees initiated new structural roots shortly after suckering. Live roots were often connected to the stump of dead and decayed trees. Grafting was common, especially at or near the stumps. Death of trees along the parent roots over time did not seem to favour the entry of significant decay, nor promote breakage of the original root connections. Instead of becoming independent of the parent root system the ramets incorporated the parent roots into their own root systems, remaining interconnected.     

上海市地面藓类植物生态位研究

在上海市市区和西部郊区主要公园,以及吴泾化工厂和吴淞化工厂,共设立22个样点,调查发现共有7种地面藓类植物.根据Levins公式计算了7种藓类植物的生态位宽度.结果表明,藓类植物种数与生态位宽度符合:N=0.344×e^-0.0377B,R=0.9684.大部分地面藓类植物生态位宽度很窄,68%种类生态位宽度小于0.1,因而在苔藓植物保护中应特别注意对小生境的保护.运用王刚的生态位重叠公式计测了其中重要值大于0.1的39种主要藓类植物的生态位重叠值,应用主坐标排序法和最小生成树法对它们进行分类.结果表明,这39种藓类植物可被分成5个生态类群,与生境有一定关系.     

Causes of the large variation in bryophyte species richness and composition among boreal streamside forests

Questions: Boreal forests along small streams are bryophyte diversity hotspots because they are moist, productive and relatively high pH. Do these factors also explain the large differences in species richness and species composition found among streamside sites? Do the species of species‐poor sites represent nested subsets of the species of more species‐rich sites? How do the results apply to conservation? Location: Forests along small streams in mid‐boreal Sweden. Methods: Survey of the flora of liverworts and mosses and habitat properties, including calculation of a pH‐index based on species indicator values, in 37 sites (1000‐m² plots). Results: The number of bryophyte species per plot ranged from 34 to 125. Neither soil moisture nor basal area of trees (a proxy for productivity) correlated significantly with species richness and composition, whereas pH‐index and cover of boulders did. Species richness and composition were more strongly correlated with pH‐index for mosses than for liverworts. The richness and composition of bryophyte species most frequently found on moist ground, stream channel margins and, most unexpected, woody debris were all more strongly associated with the pH‐index than with other habitat properties. Although species composition was significantly nested, there was still some turnover of species along the first ordination axis. Conclusions To attain high numbers of species, streamside forests need to have boulders and at least pockets with higher soil and stream‐water pH. The number of Red list species was weakly correlated with total species richness and the most species‐rich sites contained many species found more in non‐forest habitats. Hence, bryophyte conservation in streamside forests should not focus on species‐rich sites but on the quality and quantity of substrate available for assemblages of forest species that are strongly disfavoured by forestry.     

一种值得关注的藓类植物:长柄蓑藓及其地理分布

长柄蓑藓(Macromitrium microstomum(Hook.&Grev.)Schwaegr.)曾以Macromtrium reinwardtii的学名在我国台湾,海南和云南有记录。报道了该种在西双版纳纳板河国家自然保护区的新分布。在查检模式标本和相关国内外标本和文献的基础上,对长柄蓑藓进行了描述和图示,讨论了该种泛热带的地理分布特点,并提供了世界分布图。     

Gravitropic moss cells default to spiral growth on the clinostat and in microgravity during spaceflight

In addition to shoots and roots, the gravity (g)-vector orients the growth of specialized cells such as the apical cell of dark-grown moss protonemata. Each apical cell of the moss Ceratodon purpureus senses the g-vector and adjusts polar growth accordingly producing entire cultures of upright protonemata (negative gravitropism). The effect of withdrawing a constant gravity stimulus on moss growth was studied on two NASA Space Shuttle (STS) missions as well as during clinostat rotation on earth. Cultures grown in microgravity (spaceflight) on the STS-87 mission exhibited two successive phases of non-random growth and patterning, a radial outgrowth followed by the formation of net clockwise spiral growth. Also, cultures pre-aligned by unilateral light developed clockwise hooks during the subsequent dark period. The second spaceflight experiment flew on STS-107 which disintegrated during its descent on 1 February 2003. However, most of the moss experimental hardware was recovered on the ground, and most cultures, which had been chemically fixed during spaceflight, were retrieved. Almost all intact STS-107 cultures displayed strong spiral growth. Non-random culture growth including clockwise spiral growth was also observed after clinostat rotation. Together these data demonstrate the existence of default non-random growth patterns that develop at a population level in microgravity, a response that must normally be overridden and masked by a constant g-vector on earth.