Notes on the bryophyte communities oe lowland Tropical Rain Forest,with special reference to Moraballi Creek,British Guiana

Discussion and conclusions The four main bryophyte synusiae in the Moraballi Creek rain forest (high epiphytes, shade epiphytes, epiphyllae, synusia on dead wood) are remarkably distinct both in structure and floristic composition, though there are a few very frequent species, e.g. Calymperes lonchophyllum, Octoblepharum albidum, which occur in all the synusiae except the epiphyllous, which consists almost entirely of highly specialised species exclusive to itself. The differences in the structure of the synusiae depend on the different growth forms of the more abundant species. Data are not available for a satisfactory analysis of these growth forms (like that, for instance of Gimingham & Robertson, 1950, for some British bryophyte communities), but from the general observations given above it is obvious, for instance, that there are wide differences between the growth forms of the strongly xeromorphic high epiphyte synusia and those of the shade epiphyte synusia, characterised by markedly hygromorphic features such as freely projecting or dangling shoots and large thin-walled cells. Again, there are conspicuous differences between the growth forms prevailing in the shade epiphyte and dead wood communities. The differences in floristic composition and structure between the various bryophyte synusiae reflect the marked differences in microclimatic and other ecological factors existing between the various microhabitats available for bryophytes within the rain forest community.When the bryophyte synusiae of the Moraballi Creek rain forest are compared with those of temperate deciduous or coniferous forests the most striking differences seen are the absence in the former of any bryophyte synusia on the ground, the presence of an epiphyllous community and the pronounced dominance of hepaticae, especially of the family Lejeuneaceae, in all microhabitats except the dead trunks and stumps. In conclusion it may be noted that the bryophyte flora of the lowland rain forest is not excessively rich in species, indeed area for area it is probably poorer than many temperate forests. The comparatively restricted bryophyte flora, compared with the overwhelmingly rich angiosperm flora is a surprising fact. These comparisons, though based in the first place on the Moraballi Creek forest alone, would apply to lowland rain forests in Africa or the Indo-Malayan region. In montane forests conditions differ greatly from those in the lowlands and some of the above conclusions no longer apply.Received for publication 11.XI.1953.     

Relationship between field-layer vegetation and canopy openings in a Carpathian subalpine spruce forest

The field-layer structure relative to the distribution of canopy gaps was analysed in a subalpine spruce forest in the Babia Góra massif – one of the highest in the Polish West Carpathians. Nineteen synusiae (floristically, physiognomically and ecologically homogenous one-layered vegetation units) in the field-layer were distinguished on the basis of the dominance of 8 vascular plants and 1 moss species. The presence of synusiae was noted in a grid of points spaced at 10 × 10 m which was established in a 14.4 ha area. This grid was then laid over a map of gap distribution. The main results are: 1. Nearly 2/3 of the area was covered with two mono-dominant synusiae: Athyrium distentifolium and Vaccinium myrtillus. 2. The spatial structure of the field layer was related to the distribution of gaps. A significant departure from a random distribution was noted for eight synusiae, which together covered 88% of the area under the spruce canopy and 92% in gaps. 3. The percentage of area covered by Athyrium distentifolium in gaps was nearly twice as great as outside them. A positive relationship to gaps also showed patches dominated by Calamagrostis villosa and Dryopteris dilatata + Rubus idaeus, while a negative relationship occurred for synusiae dominated by: Dryopteris dilatata, Vaccinium myrtillus, V. myrtillus + D. dilatata, and V. myrtillus + Polytrichum formosum. 4. There were significant differences in the structure of the field layer between the understory of closed stands and in gaps larger than 50 m². This means that even a small-scale disturbance touching a few trees and causing only a small modification in light and soil conditions can result in considerable changes in the field-layer vegetation in subalpine spruce forests.     

阿拉善荒漠区一年生植物层片物种多样性及其分布特征

一年生植物层片是阿拉善荒漠区荒漠与绿洲生态系统的恒有植物层片,对荒漠生态系统的稳定和当地畜牧业的生产都有重要作用．对该层片的物种多样性及其在群落中的分布特征分析表明,荒漠与绿洲生态系统中,一年生植物层片植物种有12科35属61种,可归为一年生小禾草、一年生猪毛菜、一年生蒿类和一年生杂类草4个类群,并可划分成12种区系地理成分,其中有10个阿拉善或近阿拉善特有种．一年生植物层片广泛分布于土质、沙砾质、沙质、砾质、石质、盐土荒漠及各种类型的绿洲群落中,常一种或几种组成层片,均匀或斑块状分布,或沿水线分布．此外,还分析和评价了一年生植物层片在群落中的分布差异、生态适应模式与功能．     

The ‘masking effect’ of silviculture on substrate-induced plant diversity in oak-hornbeam forests from northern France

Traditional measures of plant diversity from phytosociological relevés are used to compare floristical richness and diversity between different oak-hornbeam forest stands of Thiérache (Northern France). Five sets of physiognomically similar forests are distinguished according to the geological substrate: schists and sandstones, loess on schists, loess on calcareous rocks, jurassic limestones, cretaceous marls and clays. Plant species diversity is investigated at two scale levels: a phytocoenotic level and a synusial one which is supposed to partly avoid a possible silviculture-related bias. Two pools of sets may be distinguished: a calcareous and a non-calcareous one. The calcareous shows the highest floristical diversity, and the non-calcareous one the highest phytosociological richness. For each inter-pool pair of sets, plant species diversity is significantly different at the phytocoenotic level as well as at the level of herbaceous or shrubby synusiae, but not at the arborescent one. Through the coppice-with-standards practice, silviculture was the main determining factor for arborescent synusiae while the herbaceous and shrubby synusiae, which support the major part of the diversity, remained strongly influenced by the substrate. It is suggested that silviculture has got a masking effect on plant species diversity within oak-hornbeam managed forests by making uniform tree layers that outshine the understory vegetation diversity.     

大兴安岭东西两侧山地线叶菊草原分异现象的初步分析

本文对大兴安岭东西两侧山地线叶菊草原植被的区系组成、生态类群、层片、地上植物量以及空间组合等进行了比较分析,讨论了线叶菊草原群落的多样性及群系内部进一步分化原因,可作为植被分区研究参考的指标之一。     

The mosaic diversity of field layer vegetation in the natural and exploited forests of Białowieża

The main focus of the study was to find out whether and how the forestry management in the Biaowiea Forest has influenced the mosaic diversity of field layer vegetation and habitat heterogeneity in the temperate hard wood forest (Tilio-Carpinetum). Five belt-transects represent natural and semi-natural old-growths in Biaowiea National Park (BNP), the commercial forest (CF), and secondary stands in the CF. Along the transects, distinct patches of field layer vegetation were identified and delimited, and their species composition was assessed. Along central lines of the transects the environmental data was collected from sample points established at regular intervals: soil pH and the distances to the 4 closest trees, their species, and dbh (diameter at the breast height=135 cm). The group of patches (on average 50 per transect) was subjected to the dichotomous classification in order to identify a number of characteristic types of microphytocoenoses – synusiae. Beta-diversity of the vegetation was expressed with the Simpson diversity index calculated on the basis of areas occupied by synusiae. The most structurally diversified were the transects representing natural old-growths in the BNP. A calculation of similarity coefficients between the transects on the basis of their mosaic composition displayed sharper differences between old-growth and secondary communities in summer than those found in spring. Forestry management has seriously modified the tree species composition in two studied stands, through planting oak or initiating succession. This resulted, both in plantation and pioneer stand, in loss of the main components of natural old-growths: hornbeam (Carpinus betulus), Norway spruce (Picea abies), lime (Tilia cordata) and maple (Acer platanoides). Significantly a wider range of soil pH values in natural old-growths coincided with a higher diversity of herbaceous mosaics comparing to secondary stands. The elimination of spruce (the species being most commonly blown down, projecting an acid canopy shadow) in two studied areas, elimination of dead wood, and destruction of humus layers through ploughing, could contribute to a reduction of specific microenvironments. A lower mosaic diversity of secondary stands coinciding with the unification of environmental conditions along the transects may indicate that forestry management can lead to the disappearance of a highly structural character in natural forest communities.Nomenclature: Flora europaea; Sokoowski (1993).     

The whole and its parts: why and how to disentangle plant communities and synusiae in vegetation classification

Most plant communities consist of different structural and ecological subsets, ranging from cryptogams to different tree layers. The completeness and approach with which these subsets are sampled have implications for vegetation classification. Non‐vascular plants are often omitted or sometimes treated separately, referring to their assemblages as “synusiae” (e.g. epiphytes on bark, saxicolous species on rocks). The distinction of complete plant communities (phytocoenoses or holocoenoses) from their parts (synusiae or merocoenoses) is crucial to avoid logical problems and inconsistencies in the resulting classification systems. We here describe theoretical differences between the phytocoenosis as a whole and its parts, and outline consequences of this distinction for practice and terminology in vegetation classification. To implement a clearer separation, we call for modifications of the International Code of Phytosociological Nomenclature and the EuroVegChecklist. We believe that these steps will make vegetation classification systems better applicable and raise recognition of the importance of non‐vascular plants in the vegetation as well as their interplay with vascular plants.     

Degradation of polysaccharides and lignin in wood ozonation

Ozonation has been considered as a method for the pretreatment of plant biomass to obtain cellulose and monosaccharides. Ozone consumption by aspen wood with various moisture contents has been investigated. We have considered the gradual transformation of the substrate: wood to ozonated wood to cellulose-containing product (CP) to holocelluloze (HC) and to cellulose. Yields of ozonated wood (OW), the (CP), water-soluble ozonation products, HC, and cellulose have been determined. The lignin content in the CP has been estimated. Both HC and cellulose samples have been studied by IR spectroscopy. The degree of polymerization and molecular mass distribution of cellulose obtained from ozonated wood have been determined. It has been shown that wood destruction by ozone is accompanied by degradation of lignin, hemicelluloses, and cellulose.It has been found that physicochemical properties of cellulose obtained from ozonated wood can be regulated by the variation of the initial moisture content in the substrate. Both molecular ozone and radical species, which are generated in the course of ozone reactions with water present in the substrate structure, participate in wood destruction.     

西藏芜塘高原高寒草原的基本类型与特征

 羌塘高原,地势高亢,气候寒冷干旱,发育着面积广阔的高寒草原植被。本文论述了高寒草原的区系组成,地理成分、生活型和层片、生态类群与生长发育节律等方面的特点,描述了7个主要群落类型,并探讨了它们的生态地理分布规律。在对羌塘高寒草原与我国温带草原进行比较分析的基础上,将高寒草原作为植被亚型,与温带草原并列于草原植被型之下;在进行地植物学区划时,应该充分考虑羌塘高原高寒草原的广泛分布及其地带性景观意义。     

Carboxymethylation of pine wood subjected to microwave irradiation after pretreatment in an “acetic acid-hydrogen peroxide-water-catalyst” system

Pretreatment of pine wood in a mixture containing acetic acid, hydrogen peroxide, water, and catalyst has been performed in order to minimize wood component destruction and analyze the behavior of the principal components of pine wood upon carboxymethylation. The effects of catalysts (sulfuric acid or ammonium molybdate) and the characteristics of the microwave radiation on the composition of the solid residue have been investigated. The reaction of pine wood carboxymethylation after pretreatment in a mixture of acetic acid, hydrogen peroxide, water, and catalyst has been studied. Formation of highly substituted carboxymethylated derivatives containing 17–29% carboxymethyl groups has been demonstrated for pine wood. Solubility of carboxymethylated pine wood depended on the nature of the catalyst used during pretreatment. Carboxymethylation products obtained with sulfuric acid as catalyst had the highest solubility.     

西藏羌塘高原高寒草原的基本类型与特征

羌塘高原,地势高亢,气候寒冷干旱,发育着面积广阔的高寒草原植被。本文论述了高寒草原的区系组成,地理成分、生活型和层片、生态类群与生长发育节律等方面的特点,描述了7个主要群落类型,并探讨了它们的生态地理分布规律。在对羌塘高寒草原与我国温带草原进行比较分析的基础上,将高寒草原作为植被亚型,与温带草原并列于草原植被型之下;在进行地植物学区划时,应该充分考虑羌塘高原高寒草原的广泛分布及其地带性景观意义。     

Wood cell walls: biosynthesis, developmental dynamics and their implications for wood properties

Progress has been made toward understanding the biosynthesis and modifications of the cellulose and the hemicellulose/pectin matrix of woody cell walls (and hence wood properties) by identifying 1600 carbohydrate active enzymes (CAZYmes) in Populus, and pinpointing key candidates involved in various developmental stages of wood formation. Transgenic modifications of primary wall modifying enzymes have demonstrated on the possibility of shaping the dimension of wood cells. Candidates for the biosynthesis of secondary wall matrix have been identified, and the cellulose microfibril angle of wood fibers has been modified. In addition, molecular analysis of the plastic development of wood cell walls has provided further information regarding the mechanisms regulating their structure.     

Variation in vernal species composition in alluvial forests of the Rhine valley,eastern France

Patterns of vernal synusiae in alluvial forests of the upper Rhine valley were analysed phytosociologically. Five synusial types were described. Environmental factors included in the analysis were spring water level, texture, trophic status and soil reaction. A separate environmental study was undertaken in pure stands of six competitive geophytes in the most fertile habitats. In a laboratory experiment effects of water stress and interspecific competition were studied for three competitive geophytes. The vernal species can be grouped into eight groups with respect to species position along the environmental gradients occurring in the floodplain. These groups can be used for bioindication.     

A life cycle evaluation of wood pellet gasification for district heating in British Columbia

The replacement of natural gas combustion for district heating by wood waste and wood pellets gasification systems with or without emission control has been investigated by a streamlined LCA. While stack emissions from controlled gasification systems are lower than the applicable regulations, compared to the current base case, 12% and 133% increases are expected in the overall human health impacts for wood pellets and wood waste, respectively. With controlled gasification, external costs and GHG emission can be reduced by 35% and 82% on average, respectively. Between wood pellets and wood waste, wood pellets appear to be the better choice as it requires less primary energy and has a much lower impact on the local air quality.     

Integrated synusial phytosociology: some notes on a new,multiscalar approach to vegetation analysis

Abstract. The integrated synusial approach of the vegetation is based on the differentiation of several spatio-temporal organization levels. A phytocoenosis (community of the second level) is considered as a complex of synusiae (communities of the first level) and is characterised by a strong tendency to self-organization. At each level, a typology of the communities can be performed. Ecological indicator values as well as different diversity indices are calculated for each vegetation unit. They are useful for understanding the spatial and temporal organization of the phytocoenoses. As an example. this approach is applied to wooded meadows.     

Thoughts on rationing medical care

The use of wood stoves has increased greatly in the past decade, causing concern in many communities about the health effects of wood smoke. Wood smoke is known to contain such compounds as carbon monoxide, nitrogen oxides, sulfur oxides, aldehydes, polycyclic aromatic hydrocarbons, and fine respirable particulate matter. All of these have been shown to cause deleterious physiologic responses in laboratory studies in humans. Some compounds found in wood smoke--benzo[a]pyrene and formaldehyde--are possible human carcinogens. Fine particulate matter has been associated with decreased pulmonary function in children and with increased chronic lung disease in Nepal, where exposure to very high amounts of wood smoke occurs in residences. Wood smoke fumes, taken from both outdoor and indoor samples, have shown mutagenic activity in short-term bioassay tests. Because of the potential health effects of wood smoke, exposure to this source of air pollution should be minimal.     

Gravimetric screening method for fungal decay of paper: inoculation with <Emphasis Type="Italic">Trametes</Emphasis> <Emphasis Type="Italic">versicolor</Emphasis>

The European standard test EN 113 for fungal degradation of solid wood has been adapted for degradation of paper by white rot fungus (Trametes versicolor). Fungal degradation of paper sheets may potentially be used for screening different wood preservatives on paper instead of solid wood. The paper samples showed higher relative mass losses compared to wood, and samples pretreated with boric acid, copper sulfate and polymerized linseed oil were successfully tested for biodegradation using the paper sheet method. The results on paper degradation were compared with wood, both as wood blocks (according to standard test) and wood cut in sections forming layered structures mimicking paper layers.     

Ciclo Di Accrescimento E Differenzazione Delle Gemme in Piante Perenni Nel Territorio Di Bari

Summary

The evolution of cambial activity during one year in Viburnum Tinus L. in Bari has been studied. The research seems to be particularly difficult in this evergreen shrub. The wood is of the porous diffused type with scarse evidence of wood rings. The vessel diameter varies rather irregularly in the wood ring; on the other side the fibers show wide variations and may be assumed as a good index of the wood ring evolution. Both in the branch and in the stem only one wood ring each year is formed.

Cambial activity prosecutes during the whole year, with an irregular step. During the period July-beginning of September the cambium devides very slowly, or possibly stops deviding.

The early wood is produced earlier in the branch than in the stem; namely in February-end of May in the branch and in March-beginning of June in the stem. The stimulating growth stuffs evidently proceeds downwards from the top to the base of the plant. The relations between ring evolution and climatic factors are discussed. The peculiar cambial poussée during the month of June seems to be correlated with the exceptionally aboundant rainfall of May in Puglia in 1947.

The late wood is formed during the other months discontinuosly. The alternation between the two phases of cambium division and wood lignification has been focussed. The wood ring in Viburnym Tinus is annual and the early wood differentiates in spring.     

Blood parasites in wood storks (Mycteria americana) from the southeastern United States

Wood storks (Mycteria americana) are endangered throughout their breeding range in the United States. Because of this, researchers have had little opportunity to thoroughly examine the continental wood stork population for endoparasites. The blood protozoan Haemoproteus crumenium has been identified from several populations of wood storks in North America. However, there have been no reports of wood storks being infected with species of Plasmodium or Leucocytozoon. During 2003, 42 nestling wood storks were captured at sites in Georgia and 27 free-ranging wood storks were captured at postbreeding dispersal sites in Mississippi and Louisiana. Two thin blood smears were made from each bird, and they were examined for parasites. Haemoproteus crumenium was found in 5 wood storks (7.2%), whereas Leucocytozoon sp., Plasmodium sp., and microfilariae were not observed. Mean intensity of H. crumenium was 4.4 +/- 0.7 (SE) per 2,000 erythrocytes counted. All infected wood storks were subadult or adult and were from postbreeding dispersal sites in Mississippi.