Phytotoxic Potential of Onopordum acanthium L. (Asteraceae)

Onopordum acanthium L. (Asteraceae) is a plant native to southern Europe and southwestern Asia, but it is invasive in disturbed areas and agricultural fields around the world, causing many agronomic problems by interfering with crops or preventing animals from grazing on pastures. Allelopathy could be one of the reasons that this plant has spread over different continents. The aim of the present study was to bioprospect O. acanthium leaf extracts through the isolation and purification of allelopathic secondary metabolites with phytotoxicity to explain their invasive behavior. Phytotoxic activity was tested using etiolated wheat coleoptiles. The most active extract was selected to perform a bioassay‐guided isolation of two flavonoids, pectolarigenin ( 1 ) and scutellarein 4′‐methyl ether ( 2 ), and two sesquiterpene lactones, elemanolide 11(13)‐dehydromelitensin β‐hydroxyisobutyrate ( 3 ) and acanthiolide ( 4 ). All compounds were isolated for the first time from O. acanthium, and acanthiolide ( 4 ) is described for the first time. Compound 3 strongly inhibited the growth of wheat coleoptiles and 1 showed an intermediate effect. The results indicate that these compounds could contribute to the invasion of O. acanthium in ecological systems and agricultural fields.     

Intergenic spacers of rRNA genes in three species of theCynareae (Asteraceae)

Intergenic spacers of the rRNA genes of three species of theCynareae tribe:Cynara cardunculus subsp.scolymus (artichoke),Onopordum acanthium, andO. illyricum were cloned in the plasmid pGEM-7zf(+). Detailed restriction mapping and partial sequencing of the IGSs were carried out. The structural analysis showed a clear diversity betweenCynara andOnopordum, while a high degree of homology was found between the twoOnopordum spp. In all three species a fragment of about 450 bp from the 5 end of 18S to the Acc I site with a high sequence homology was present. Nucleotide sequences upstream from the above mentioned Acc I site show a gradual decrease of homology betweenCynara andOnopordum.     

狭义蛇葡萄属东亚支系的系统发生与生物地理演化

狭义蛇葡萄属(Ampelopsis s. str.)是葡萄科的落叶木质藤本植物,主要分布在北半球温带地区,特别是东亚为其重要的分布和演化中心。该研究选取了狭义蛇葡萄属15个种的37个样本,对其5个叶绿体基因片段(trnL-F、rps16、psbA-trnH、atpB-rbcL和trnK-petN)和2个核基因标记(ITS和GAI1)进行了分子测序;利用测序获得的分子数据探讨属内的系统发生关系,叶的性状演化以及生物地理起源演化。结果表明：(1)狭义蛇葡萄属是一个单系类群,属内东亚地区的物种聚成一支。(2)叶绿体基因数据分析结果表明,狭义蛇葡萄属东亚支系分为两支系,这两支系的分布范围大致与东亚植物区系的中国-日本森林和中国-喜马拉雅森林亚区范围相一致。(3)形态演化分析表明,掌状复叶为祖征,叶形态性状存在多次的独立起源和演化,其变化与系统进化没有明显的关系。(4)生物地理分析结果表明,狭义蛇葡萄属起源于北美,渐新世晚期至中新世早期迁移扩散至欧洲,中新世中期随着全球气温回暖迁移至东亚,并进一步在东亚地区快速分化形成多样化中心,这可能与中新世时期的气候温暖、受第四纪冰川影响较少以及东亚地区复杂...     

Taxonomy and ecology of <Emphasis Type="Italic">Castanea sativa</Emphasis> Mill. forests in Greece

Castanea sativa Mill. is an important species of the Balkan Peninsula with high ecological and economic value. This article contributes to a phytosociological synsystematic approach of the C. sativa plant communities in Greece that covers the southern part of the Balkan Peninsula and describes the ecological parameters involved in their distribution and taxonomy. Phytosociological data have been collected from 14 mountainous areas across continental Greece, which are considered representative of the main forest types of C. sativa in the area. The 14 mountains demonstrate a variety of environmental conditions. Five communities (associations) and seven sub-communities (sub-associations) have been identified and described using TWINSPAN, Corespondence Analysis and the Braun-Blanquet classification scheme. Castanea sativa (chestnut) forests of Greece can be distinguished as three broad groups, defined primarily by their geographical distribution. In northern and central Greece chestnut stands are characterized by their high floristic homogeneity, which is reflected in the identification of only one community per region. Chestnut forests in northern Greece, in particular, exhibit strong floristic similarities with those of the rest of the Balkans. In southern Greece, on the other hand, the southern distribution limit of chestnut in the Balkans, there is a greater floristic diversity between the sampled mountains which is reflected in the presence of three confirmed communities and two sub-associations. Several factors have been identified as important in determining the structure and floristic composition of chestnut forests in Greece. Whilst climate and the grazing regime are influential, the degree of silvicultural management appears to be the most important factor determining the floristic composition of chestnut forests and their long-term sustainability.     

Ribosomal RNA genes in species of theCynareae tribe (Compositae). I.

Summary By means of Southern blot hybridization, the structure of the ribosomal DNA in six species of theCynareae tribe has been analyzed. Artichoke and wild artichoke possess only one type of ribosomal genes 13 kb long;Onopordum acanthium has at least two types of rDNA repeats 9.9 kb and 10.3 kb long andO. illyricum has a third gene type 9.7 kb long; inGalactites tomentosa there are at least four ribosomal gene types of 10.9, 11.6, 11.5, and 10kb;Carduus nutans possesses two ribosomal gene types of the same length of 12.5 kb that vary in the nucleotide sequence of the external spacer. The rRNA genes of all the species studied have an identical restriction mapping in the 18 S and 25 S regions, differences in length and/or nucleotide sequence are present in the external spacer.     

Small-scale disturbances spread along trophic chains: leaf-cutting ant nests, plants, aphids, and tending ants

Small-scale disturbances caused by animals often modify soil resource availability and may also affect plant attributes. Changes in the phenotype of plants growing on disturbed, nutrient-enriched microsites may influence the distribution and abundance of associated insects. We evaluated how the high nutrient availability generated by leaf-cutting ant nests in a Patagonian desert steppe may spread along the trophic chain, affecting the phenotype of two thistle species, the abundance of a specialist aphid and the composition of the associated assemblage of tending ants. Plants of the thistle species Carduus nutans and Onopordum acanthium growing in piles of waste material generated by leaf-cutting ant nests (i.e., refuse dumps) had more leaves, inflorescences and higher foliar nitrogen content than those in non-nest soils. Overall, plants in refuse dumps showed higher abundance of aphids than plants in non-nest soils, and aphid colonies were of greater size on O. acanthium plants than on C. nutans plants. However, only C. nutans plants showed an increase in aphid abundance when growing on refuse dumps. This resulted in a similar aphid load in both thistle species when growing on refuse dumps. Accordingly, only C. nutans showed an increase in the number of ant species attending aphids when growing on refuse dumps. The increase of soil fertility generated by leaf-cutting ant nests can affect aphid abundance and their tending ant assemblage through its effect on plant size and quality. However, the propagation of small-scale soil disturbances through the trophic chain may depend on the identity of the species involved.     

Chorological phenomena of the Molinietalia communities in Czechoslovakia

Forty Molinietalia communities were analyzed from the phytogeographical point of view in order to establish their distribution tendencies in Czechoslovakia in relation to the floristic regions of Hercynicum, Pannonicum and Carpaticum. Only few moist meadow communities of the Molinietalia order are found in the whole area under study; most of them have their distribution center in one of the floristic regions mentioned above. Eleven Calthion and two Molinion associations are confined to the Hercynicum, eight of them strictly. It is only in the Moravian and Slovak Pannonicum that all associations of the alliances Cnidion venosi and Veronico longifoliae-Lysimachion occur; they appear there together with two Molinion communities, the distribution of which is, however, a little wider. Three Calthenion communities show a still wider distribution, extending into the adjoining areas. One Calthenion community occurs in the Bohemian Pannonicum and its surroundings, two Calthenion associations have their distribution center in the Carpaticum, but they are not strictly confined to it.The author wants to express her thanks to Doc. Dr Miroslav Smejkal, CSc., for critical revision of the text.     

南京市加拿大一枝黄花入侵地群落的物种组成与多样性特征研究(附表)

为探究外来植物加拿大一枝黄花(Solidago canadensis)入侵与南京市本土植物多样性的关系,该文采用踏查及样方调查对其入侵地群落的物种组成与多样性进行研究。结果表明:(1)入侵地群落中共有维管植物200种(含种下单元),隶属于62科156属,其中被子植物195种,裸子植物1种,蕨类植物4种; 数量最多的是菊科(Asteraceae)和禾本科(Poaceae)植物,分别有25种和24种; 从生活型来看,草本植物占多数,有133种,占所有种的66.50%; 此外,群落内尚有其他外来植物29种。群落中重要值最大的是加拿大一枝黄花,为40.00%; 其次是救荒野豌豆(Vicia sativa),为7.00%。(2)从植物区系看,非入侵地中植物科的区系分布型共4个,而入侵地植物科的区系类型仅有3个,其中泛热带分布、世界分布和北温带分布为两者均有,东亚和北美间断分布型仅在非入侵地中存在。非入侵地植物科的区系以世界分布型为主,有13科,占该类型群落中所有科的39.39%; 入侵地则以泛热带分布型为主,有16科,占总科数的45.71%。非入侵地中植物属的区系分布型有10个,而入侵地有12个,两者区系成分相近,旧世界热带型和热带亚洲至热带大洋洲分布型仅在入侵地中出现。北温带分布型和世界分布型同为两者中最主要成分。入侵地及非入侵地群落属的区系R/T值分别为0.58和0.38,种系分化度分别为3.29和3.11。(3)重度入侵群落的Margalef指数(E)与非入侵及轻度入侵群落相比,显著降低; 此外,重度入侵群落的Simpson指数(D)、Shannon-Weiner(H'')指数和Pielou指数(J)均显著低于非入侵、轻度入侵、中度入侵群落。(4)不同生境之间加拿大一枝黄花群落的E、D、H''和J均无显著性差异。该研究可为南京地区的加拿大一枝黄花入侵地的治理防控和生态恢复,以及进一步的科学研究提供强有力的理论支撑。     

Exotic thistles increase native ant abundance through the maintenance of enhanced aphid populations

Exotic species change the structure and composition of invaded communities in multiple ways, but the sign of their impact on native species is still controversial. We evaluated the effects of the thistles Carduus thoermeri and Onopordum acanthium—two of the most abundant exotic plant species in disturbed areas of the Patagonian steppe—on the native tending ant assemblage. Exotic thistles showed an increased number of plants with aphids and had greater aphid density than native plants. Since native tending ants were present only in plants with aphids, their abundance was higher in infested thistles than in native plants. Path analyses confirmed that ant activity depended more on aphid density than on thistle traits. Our results suggest that the presence of exotic thistles in disturbed areas of NW Patagonia indirectly benefit the native ant assemblage through the maintenance of an increased aphid population. This illustrates how the impact of exotic on native species can depend on the ecological context.     

Climate‐driven changes to the spatio‐temporal distribution of the parasitic nematode,Haemonchus contortus,in sheep in Europe

Recent climate change has resulted in changes to the phenology and distribution of invertebrates worldwide. Where invertebrates are associated with disease, climate variability and changes in climate may also affect the spatio‐temporal dynamics of disease. Due to its significant impact on sheep production and welfare, the recent increase in diagnoses of ovine haemonchosis caused by the nematode Haemonchus contortus in some temperate regions is particularly concerning. This study is the first to evaluate the impact of climate change on H. contortus at a continental scale. A model of the basic reproductive quotient of macroparasites, Q₀, adapted to H. contortus and extended to incorporate environmental stochasticity and parasite behaviour, was used to simulate Pan‐European spatio‐temporal changes in H. contortus infection pressure under scenarios of climate change. Baseline Q₀ simulations, using historic climate observations, reflected the current distribution of H. contortus in Europe. In northern Europe, the distribution of H. contortus is currently limited by temperatures falling below the development threshold during the winter months and within‐host arrested development is necessary for population persistence over winter. In southern Europe, H. contortus infection pressure is limited during the summer months by increased temperature and decreased moisture. Compared with this baseline, Q₀ simulations driven by a climate model ensemble predicted an increase in H. contortus infection pressure by the 2080s. In northern Europe, a temporal range expansion was predicted as the mean period of transmission increased by 2–3 months. A bimodal seasonal pattern of infection pressure, similar to that currently observed in southern Europe, emerges in northern Europe due to increasing summer temperatures and decreasing moisture. The predicted patterns of change could alter the epidemiology of H. contortus in Europe, affect the future sustainability of contemporary control strategies, and potentially drive local adaptation to climate change in parasite populations.     

Rumex aquaticus L. at Loch Lomondside

Summary

A new alliance of spring vegetation dominated by the leafy liverwort Anthelia julacea is described from the montane regions of Britain. It is distinguished floristically and ecologically from similar alpine late snow bed communities in Scotland and Scandinavia. The classificatory position of the stands of this vegetation type is discussed with reference to continental and British systems and it is concluded that the erection of a new alliance is justified on floristic grounds.     

Corresponding Caricion bicolori-atrofuscae communities in western Greenland,northern Europe and the central European mountains

The alliance Caricion bicolori-atrofuscae comprises plant communities of more or less wet calcareous fens on shallow peat with a high base saturation, occurring in arctic as well as alpine, more seldom subalpine areas. The characteristic species are presented and compared with those from communities of the Caricion lavallianae growing in lowland and mountain sites of temperate and boreal calcareous fens.An abbreviated ecological characteristic is given and the contact communities of the different community complexes are pointed out. The regional floristic differences within the communities are shown, and the geographical distribution and regional frequency of the differentiated associations are given. The synsystematic ranks of three central European mountain to alpine associations are discussed in detail (Caricetum frigidae, Juncetum alpini, Equiseto-Typhetum minimi). They should be excluded from this alliance.Generally, the alpine phytocoenoses are more often invaded by species from neighbouring communities, presumably as an effect of competition in sites less favouring fen development in comparison to the oro-arctic and arctic sites, especially those with an oceanic to suboceanic climate.We conclude, that the observed floristic differences are mainly caused by historical processes and not by the different ecology of the sites in question. This must be taken into consideration when discussing the synsystematic delimitation and rank of the corresponding communities.Nomenclature follows: Lid (1974), Nyholm (1954–68). Acknowledgement. The authors are grateful to the Deutsche Forschungsgemeinschaft for travel grants since 1973 for their investigations in Scandinavia and Greenland.     

Some synchorological aspects of basiphilous pine forests in Fennoscandia

Basiphilous pine forests and related birch forests are herb-and grass-rich forests on calcareous substrate. These forests are complex communities with floristic/ecological elements from different vegetation types occurring in a subtle micromosaic. These elements are e.g. species from acidophilous conifer forests, thermophilous forest-rim communities, calcareous shallow-soil and steppe communities, eutrophic wet meadows and fens, and in northern Fennoscandia also species from alpine Dryas heaths. Four associations are recognized in Fennoscandia: Convallario-Pinetum, Melico-Piceetum pinetosum, Peucedano-Pinetum and Epipacto atrorubentis-Betuletum. The main association is the Convallario-Pinetum, a widespread community in Fennoscandia and Estonia with a considerable floristic variation between the different regions. Examples of the floristic variation along west-east profiles and south-north profiles in Fennoscandia are presented. The basiphilous pine forest complex can be divided into a number of ecological types along the moisture and nutritional gradients. A further subdivision into geographical types (races) is presented.Nomenclature follows Lid (1974) for vascular plants, Nyholm (1954–1969) for musci and Dahl & Krog (1973) for lichens.     

Population genetic structure of the Daubenton’s bat (<Emphasis Type="Italic">Myotis daubentonii</Emphasis>) in western Europe and the associated occurrence of rabies

The Daubenton’s bat is widespread and common in the UK and countries bordering the English Channel and North Sea. European bat lyssavirus 2 (EBLV-2), a rabies virus, has been detected in Daubenton’s bats in the UK and continental Europe. Investigating the relatedness of colonies and gene flow between these regions would allow regional estimates of the movement of Daubenton’s bats and thus the potential for disease transmission. The genetic structure of the Daubenton’s bat in western Europe was investigated by analysing variability at eight microsatellite loci. Genetic diversity was found to be high at all sites (H _E = 0.73–0.84), with little differentiation between bats sampled in the UK and continental Europe. Mantel tests indicated a significant correlation between geographic distance and pair-wise F _ST (P = 0.000), between colonies sampled in Scotland and northern England. However, this was not continuous throughout the sampled range, with evidence of panmixia within the area sampled in continental Europe. Assignment tests show no evidence that the (potential) EBLV-2 sero-positive and virus positive bats were more likely to have originated from the continental rather than UK populations. There is no sufficient significant genetic differentiation amongst most UK and continental colonies to conclude that EBLV-2 is maintained in the UK by immigration. Results show that it is likely to be maintained at a low endemic level within the UK. The relative genetic uniformity of UK and continental populations implies that there is no migration barrier to EBLV-2, between these regions.     

Combined effects of local environment and continental biogeography on the distribution of Ostracoda

Summary 1. The relationship between altitudinal gradients on small spatial scales and latitudinal gradients on broader scales has been repeatedly recognised in the biogeography of animals and plants. However, little is known about this topic in the ecology and biogeography of ostracod communities in Mediterranean flowing waters or the factors underlying these spatial patterns. 2. We analysed the ostracod assemblages of near‐natural headwater streams in the Betic and Pre‐Betic Mountains in the southern Iberian Peninsula to decipher the most important environmental gradients structuring ostracod communities on a local scale. In addition, the European altitudinal and latitudinal distributions of the most commonly found species were analysed with GIS and regression models to compare geographical effects from local to continental scales. 3. Forty sampling sites, distributed among six catchments and ranging in altitude between 150 and 1940 m a.s.l., were sampled seasonally. Limnological and geographical information was also recorded for each sample. Seventeen ostracod species were found, two of which were new findings for the Iberian Peninsula: Potamocypris fulva and Cypria reptans. The most common species were Potamocypris zschokkei, Candona neglecta, Herpetocypris brevicaudata, Cyclocypris ovum, Potamocypris villosa and Pseudocandona albicans. The distribution of these species in 918 European locations was analysed to test the hypothesised change in altitudinal distribution with varying latitude. 4. The best subset of logistic and linear regression models, selected by means of the information‐theoretic approach, found that oxygen content and the variables related with substratum and discharge were the most important variables with a negative influence on ostracod presence, abundance and species richness on a local scale. These findings suggest that the negative effect on benthic invertebrates of physical disturbances relates to high flow velocity and turbulences. 5. Multivariate ordination methods show how altitude and water chemistry are the most important variables to explain the distribution of ostracod assemblages on the small spatial scale. On a larger scale, differences in latitudinal distribution throughout Europe were significant for the six most common species found in Granada. In addition, four of these showed significant negative linear relationships between latitude and altitude in Europe, supporting the important effect of climate on local and continental scale distributions. While ostracod biogeographies are still poorly known, our results indicate the influence of Quaternary climate variability on ostracod dynamic colonisation and extinction in Europe in accordance with species‐specific temperature and water chemistry preferences.     

The Balkan wet grassland vegetation: a prerequisite to better understanding of European habitat diversity

The knowledge of broad-scale floristic variation in wet grasslands, which are endangered throughout Europe, is still limited and some regions have remained unexplored so far. In addition, hitherto published phytosociological studies were concentrated at the national level and therefore national vegetation classifications are not consistent with each other. In order to overcome these shortcomings of traditional phytosociology, we gathered original data from Bulgaria and analysed them together with the data from Central Europe. We further analysed major compositional gradients within Bulgarian wet grasslands and changes in species richness along them. We sampled 164 wet grassland vegetation plots throughout Bulgaria. We further prepared a restricted data set of wet grasslands from Central-European phytosociological databases. Both data sets were merged and classified by modified TWINSPAN. Four distinct vegetation types were differentiated. Even if they correspond with traditional alliances, which are primarily drawn as geographically defined units in Western and Central Europe (sub-Mediterranean Trifolion resupinati, sub-continental Deschampsion cespitosae and Molinion caeruleae and sub-oceanic Calthion palustris), they all occur in Bulgaria. When more precise classification was applied, two types of sub-Mediterranean wet grasslands and one high-altitude type of Calthion grasslands were detected solely in Bulgaria. DCA analysis showed that altitude is a dominant gradient controlling variation in Balkan wet grasslands. The second DCA axis was interpreted as the gradient of nutrient availability. Species richness shows skewed-unimodal trends along both major gradients, with the highest species richness in intermittently wet nutrient-limited grasslands. Tukey post-hoc test of altitudinal differences amongst vegetation types is significant for all pairs of clusters, suggesting that altitudinal differentiation is responsible for co-occurrence of nearly all European types of wet grasslands in Bulgaria. Our results suggest that (1) climate is an important factor for the diversity of wet grasslands; (2) Balkan vegetation of middle altitudes matches with that of Central Europe, whereas that of the lowest altitudes corresponds rather to the sub-Mediterranean region and high mountains are specific; (3) upward shift of Central-European vegetation types in southern Europe, so often described in forest vegetation is also evident for grassland vegetation and (4) the high diversity of Balkan vegetation is determined by a diverse relief enabling confluence of habitats possessing different climatic conditions.     

Subdivision ofPelargonium sect.Cortusina (Geraniaceae)

The sect.Cortusina (Dc.)Harv. s.l. is divided into the sectt.Cortusina (Dc.)Harv. s. str. andReniformia (Knuth)Dreyer, comb. nov.,P. cortusifolium L'Hérit.,P. crassicaule L'Hérit.,P. echinatum Curt.,P. magenteum J. J. A. Van der Walt, andP. sibthorpifolium Harv. remain in the sect.Cortusina s. str., while the speciesP. album J. J. A. Van der Walt,P. dichondrifolium Dc.,P. odoratissimum (L.)L'Hérit.,P. reniforme Curt., andP. sidoides Dc. are removed from the sect.Cortusina s.l. and included in the revised sect.Reniformia. Both sections are well characterized by morphological, anatomical, karyological and palynological features. The chromosomes ofCortusina s. str. are small and based upon x = 11; those ofReniformia are larger and based upon x = 8. The size and surface sculpture of the pollen grains differ markedly between the two sections. Flavones and hydrolysable tannins occur in sect.Reniformia, but are absent in sect.Cortusina s. str. After hydrolysis hydroxybenzoic acids, which are present in large amounts inReniformia, occur only in traces inCortusina. The two sections also occupy distinctly different geographical areas. A close relationship between sect.Reniformia and some species of sect.Ligularia (Sweet)Harv. is indicated by the occurrence of artificial hybrids.     

Epigeic lichen communities of taiga and tundra regions

The major physiognomic and ecological categories of the lichen-rich, epigeic communities in the boreal (taiga) and arctic (tundra) zones are defined and their syntaxonomy and ecology in Europe, Asia and North America is reviewed. In the boreal and hemiarctic areas open, dry, acidophytic lichen woodlands are widespread, especially on sandy habitats. Their epigeic lichen synusiae are usually dominated by four fruticoseCladina species, being extremely homogeneous in species composition and structure throughout the boreal zone, while the dominant trees and the other vascular plant flora of the woodlands are geographically more variable. No phytosociological classification system exists that would cover most of these communities over the circumpolar regions. Very similar communities, though much more poorly known, are found on thin soils over Precambrian rock outcrops. Other sites to produce epigeic lichen communities include open sand dunes, treeless heathlands, drier bogs and many seral stages, like those on road banks. Boreal lichen-rich communities on eutrophic soils may be developed in semiarid regions, in particular. In the Arctic, lichens are common in most communities, and the driest ones are regularly lichen-dominated, whether acidophytic or eutrophytic, chionophytic or achionophytic. Detailed syntaxonomic systems for their classification have been developed, especially in Greenland and Scandinavian mountains (in oroarctic zones in the latter regions). The richest fruticose lichen areas are in continental, hemiarctic timberline regions in northern Siberia and Canada. The southern and middle arctic subzones are also characterized by many macrolichens, such asCetraria cucullata, C. nivalis, Alectoria ochroleuca, andThamnolia vermicularis, but everywhere also small, crustose lichens are common on soil, such asRinodina turfacea andLopadium pezizoideum, which are often overlooked in vegetation analyses. The presence of microlichens and the formation of mosaic micropatterns of soil lichen communities is particularly typical of the northern arctic subzone. The conservation problems of the boreal and arctic lichen communities include overgrazing by reindeer or caribou, which has caused delichenization in some regions, extensive forest and tundra fires, use of heavy transport vehicles in forestry and tundra operations, and, locally, heavy industrial air pollution.     

Vegetation on avalanche paths in the alps

Vegetation pattern on avalanche paths in the Nordkette Mountains near Innsbruck (Tyrol, Austria) was studied using transect sampling. The plant communities represent a gradient from alpine grassland (Seslerio-Caricetum sempervirentis, via grassland with Trisetum distichophyllum) and nutrient-poor grassland (Carlino-Caricetum sempervirentis) to an avalanche grassland proper. Along this gradient disturbance decreases from higher to lower elevations. The topography of the avalanche path suggests a gradient from the central zone to the edge of the path, although a floristic zonation or grouping of species across the path cannot be detected. Disturbance and local topography are the dominant factors for the vegetation pattern on the avalanche paths investigated.Abbreviations DCA= detrended correspondence analysis     

Phylogeny and taxonomy of the oak powdery mildew Erysiphe alphitoides sensu lato

Phylogenetic analyses of Erysiphe alphitoides s. lat. using sequences of the rDNA ITS region and the D1/D2 domains of the 28S rDNA revealed a complex consisting of several genetically and morphologically distinguished taxa, including the already described Erysiphe alphitoides s. str. and E. hypophylla. The ascomata (chasmothecia) of E. hypophylla are morphologically very similar to those of E. alphitoides, but the two species are easily distinguishable by their symptoms, as well as the shape and size of the conidia. The fungus on Quercus phillyraeoides, distributed in warmer regions in southern Japan, is genetically clearly separated from E. alphitoides s. str., and morphologically characterized by having chasmothecia with appendages consistently shorter than the chasmothecial diameter. This fungus, named Erysiphe quercicola in this paper, is also able to infect some other oak species, and it is genetically identical with anamorphs on some tropical trees of other host genera. Collections of E. alphitoides s. lat. on Quercus acutissima and Q. variabilis, both belonging to Quercus sect. Cerris, are genetically distinct from E. alphitoides s. str., E. hypophylla and E. quercicola. They form two genetically and morphologically differentiated groups. The hypophyllous taxon on Q. acutissima and Q. variabilis, named Erysiphe hypogena in this paper, is characterized by forming distinctive persistent hypophyllous mycelial patches, causing necrotic discolouration of the host tissue. The epiphyllous taxon on these hosts, for which the name E. epigena is proposed, differs in having epiphyllous mycelium, smaller chasmothecia with fewer appendages, and does not cause leaf discolouration.