Showing papers in "Botanica Helvetica in 2007"
TL;DR: This work reviewed literature about seed dispersal in temperate regions and compiled data for dispersal distances together with information about the dispersal mode and plant traits, and identified seven “dispersal types” with similar dispersal lengths.
Abstract: Vittoz P. and Engler R. 2007. Seed dispersal distances: a typology based on dispersal modes and plant traits. Bot. Helv. 117: 109–124.
338 citations
TL;DR: The highest concentrations of chlorogenic acid,Hypericum perfoliatum, a widespread species in Northern Turkey, were reached when plants flowered, whereas rutin and apigenin-7-O-glucoside reached highest levels during fruit development.
Abstract: Cιrak C., Radusienė J., Janulis V. and Ivanauskas L. 2007. Secondary metabolites in Hypericum perfoliatum: variation among plant parts and phenological stages. Bot. Helv. 117: 29 – 36. The genus Hypericum is a source of biologically active compounds, notably hypericin and various phenolics. The concentrations of these compounds in plant tissues vary among plant parts and during the growing season. To determine this variation for Hypericum perfoliatum, a widespread species in Northern Turkey, wild-growing plants were harvested at five phenological stages: vegetative, floral budding, full flowering, fresh fruiting and mature fruiting. Whole shoots as well as individual parts (stems, leaves and reproductive tissues) were assayed for bioactive compounds by HPLC. In whole shoots, concentrations of secondary metabolites increased during shoot development. The highest concentrations of chlorogenic acid, hyperoside, quercitrin, quercetin and hypericin were reached when plants flowered, whereas rutin and apigenin-7-O-glucoside reached highest levels during fruit development. Of the individual plant parts, leaves did not contain any rutin, apigenin-7-O-glucoside and quercetin, and stems contained no hypericin. Reproductive parts had the highest levels of rutin, apigenin-7-O-glucoside, quercitrin, quercetin and hypericin, whereas leaves produced more chlorogenic acid and hyperoside. Compared to H. perforatum, a widely used medicinal plant, the tissues of H. perfoliatum contained similar concentrations of hypericin, less rutin, quercitrin and quercetin, and more chlorogenic acid and hyperoside. The presence of apigenin-7-O-glucoside had not been reported previously in the genus Hypericum.
56 citations
TL;DR: Billeter et al. as mentioned in this paper showed that restoration of pre-fallow plant community composition is likely to be successful if site conditions (hydrology, nutrient status) remain intact and if common habitat specialists are still present in the vegetation and/or seed bank.
Abstract: Billeter R., Peintinger M. and Diemer M. 2007. Restoration of montane fen meadows by mowing remains possible after 4–35 years of abandonment. Bot. Helv. 117: 1 – 13. The abandonment of management in Swiss fen meadows has reduced their plant species diversity and the fitness of some typical fen species. We examined whether the resumption of mowing can reverse these effects, and if so, which mechanisms are responsible for community change; we also tested whether restoration success depends on the duration since abandonment. Experimental mowing was applied to 15 montane fen meadows of NE Switzerland that had been abandoned for 4–35 years. After two years of mowing, plant species richness was 11% higher in mown plots (2 m2) than in fallow plots, approaching levels of neighbouring continuously managed fen meadows. In particular, experimental mowing significantly increased the number of fen indicator species (+15%) as well as herbs and woody species (seedlings and saplings), while grass, sedge and rush species richness was not affected. Mowing had little effect on aboveground biomass, but strongly reduced litter mass (−50%) and canopy height (−20%). Seedling densities of two common species showed opposite responses to mowing: they increased in Carex davalliana and decreased in Succisa pratensis, approaching values of continuously mown fen meadows. Duration since abandonment had no significant effect on any of the variables. Our results demonstrate a rapid recovery of montane fen plant communities irrespective of the duration since abandonment (up to 35 years). We conclude that the restoration of pre-fallow plant community composition is likely to be successful if site conditions (hydrology, nutrient status) remain intact and if common habitat specialists are still present in the vegetation and/or seed bank.
39 citations
TL;DR: Investigating whether the species richness of the world’s botanical gardens is related to their size, age and geographical location by compiling data from gardens in 124 different countries shows that even in these highly managed ecosystems, species richness can be described in terms of a relatively small number of large-scale patterns.
Abstract: Pautasso M. and Parmentier I. 2007. Are the living collections of the world’s botanical gardens following species-richness patterns observed in natural ecosystems? Bot. Helv. 117: 15 – 28. Botanical gardens aim to promote the awareness, study and conservation of plant species diversity, but little is known about the species diversity of botanical gardens themselves. We therefore investigated whether the species richness of the world’s botanical gardens is related to their size, age and geographical location by compiling data from gardens in 124 different countries. The data show that even in these highly managed ecosystems, species richness can be described in terms of a relatively small number of large-scale patterns. As with most natural ecosystems, there were positive species-area and species-age relationships. There was also a positive latitudinal gradient in species richness, which contrasts with the trend observed in natural ecosystems. This discrepancy may be due to the use of heated greenhouses at high latitudes, the rarity of old botanical gardens in the tropics, and the problem of poverty in developing countries, where most hotspots of plant biodiversity are located. There is thus a need to allocate more funds to botanical gardens in species-rich regions. This study also calls for an increase in the coordination of data management between botanical gardens.
37 citations
TL;DR: Vasilopoulos et al. as mentioned in this paper investigated how abandoned tree plantations differ from natural forests after at least 14 years of abandonment along the Nestos River in northeast Greece, and carried out 60 vegetation releves and took soil samples in each plot to determine soil texture and chemical properties.
Abstract: Vasilopoulos G., Tsiripidis I. and Karagiannakidou V. 2007. Do abandoned tree plantations resemble natural riparian forests? A case study from northeast Greece. Bot. Helv. 117: 125– 142. The conversion of a riparian forest to plantations of fast-growing, exotic species (Populus × canadensis, Robinia pseudoacacia) may alter the floristic composition and soil properties, which may prevent the regeneration of natural forests when plantations are abandoned. Along the Nestos River in northeast Greece, we investigated how former plantations differ from natural forests after at least 14 years of abandonment. We carried out 60 vegetation releves and took soil samples in each plot to determine soil texture and chemical properties. Relationships between the forest type (natural vs. abandoned plantations), the floristic composition of the understory and soil properties were analysed with classification (TWINSPAN) and ordination (DCA). There was a clear floristic differentiation between natural forest and abandoned plantations, especially those of Robinia pseudoacacia. The topsoil of abandoned plantations had a lower content of organic matter and nitrogen, and the tree layer was still dominated by the formerly planted species. However, there was a similar floristic gradient, related mainly to soil texture (sandy vs. loamy sediments), in both the natural forest and abandoned plantations. Thus, even though the establishment of natural riparian forest species in the former plantations was scanty, their present floristic composition sufficiently reflects the natural ecological gradient to serve as a basis for a management plan to restore the natural riparian forest.
17 citations
TL;DR: Examples of polyploids in other genera support the idea that this phenomenon, and in particular infrageneric polyploidy, may have contributed to the evolutionary diversification of orchids in the Iberian Peninsula.
Abstract: Amich F., Garcia-Barriuso M. and Bernardos S. 2007. Polyploidy and speciation in the orchid flora of the Iberian Peninsula. Bot. Helv. 117: 143 – 157.
16 citations
TL;DR: According to the successional model, plant species diversity is lost more rapidly on northern slopes than on western slopes, suggesting that northern slopes most urgently need an appropriate grazing management.
Abstract: Frelechoux F., Meisser M. and Gillet F. 2007. Secondary succession and loss in plant diversity following a grazing decrease in a wooded pasture of the central Swiss Alps. Bot. Helv. 117: 37 – 56.
16 citations
TL;DR: Gusewell et al. as mentioned in this paper studied how the grazing of nine vegetation types changes seasonally and between years, and how this is related to the quantity and quality of the herbage.
Abstract: Gusewell S., Pohl M., Gander A. and Strehler C. 2007. Temporal changes in grazing intensity and herbage quality within a Swiss fen meadow. Bot. Helv. 117: 57 – 73. Grazing is a possible tool for conservation management in wetlands, but a frequent problem is spatial variation in grazing intensity, which may promote the degradation of the vegetation. Temporal changes in grazing patterns may reduce this problem by leading to a more homogeneous overall use of the area. In a lakeshore wetland (2.8 ha) grazed by Scottish Highland cattle from May till September, we studied how the grazing of nine vegetation types changes seasonally and between years, and how this is related to the quantity and quality of the herbage. We observed cattle activity weekly throughout two grazing periods, determined the biomass and nutrient concentrations of the vegetation, analysed dung samples, and carried out clipping experiments to assess shoot regeneration after grazing. The annual grazing intensity varied seven-fold among vegetation types, and this pattern was closely similar in both years. In several vegetation types, however, grazing intensity changed seasonally. Cattle first grazed tall grassdominated vegetation (Phragmition, Phalaridion), which had the most digestible and nutrient-rich herbage, but the poor regeneration of dominant species forced the cattle to then graze small-sedge dominated, nutrient-poor fen vegetation (Caricion davallianae). These temporal changes in grazing patterns slightly reduced the spatial variation in grazing intensity. To take advantage of this effect, relatively long grazing seasons are preferable to shorter ones. Four years of grazing reduced the above-ground biomass production and nutrient concentrations of several vegetation types. Therefore, years without grazing may be needed to prevent a degradation of palatable plant communities with low grazing tolerance.
12 citations
TL;DR: Seeds of the Mediterranean Euphorbia boetica and E. nicaeensis are produced in summer but germinate only in autumn; they are actively dispersed by ants, which may cause them to be buried, and whether seedlings are able to emerge after burial is tested.
Abstract: Narbona E., Arista M. and Ortiz P. L. 2007. High temperature and burial inhibit seed germination of two perennial Mediterranean Euphorbia species. Bot. Helv. 117: 169 – 180. Seeds of the Mediterranean Euphorbia boetica and E. nicaeensis are produced in summer but germinate only in autumn; they are actively dispersed by ants, which may cause them to be buried. Here we tested whether the delay in germination is caused by thermodormancy, and whether seedlings are able to emerge after burial. Seeds of the perennial spurges Euphorbia boetica and E. nicaeensis were collected in four populations of southern Spain and were incubated at differing temperatures or after burial at differing soil depths. Most seeds germinated at 18–21 °C, but germination percentages were reduced at 25 °C and nearly zero at 30 °C. In E. boetica, the lack of germination at 30 °C was due to thermoinhibition, as all seeds that had not germinated at 30 °C did germinate when they were subsequently incubated at 18–21 °C. In contrast, about 15% of the viable seeds of E. nicaeensis did not germinate under these conditions, meaning that they had entered secondary dormancy. All viable seeds of E. boetica buried at 1 and 5 cm emerged, but at 10 cm emergence was significantly lower. In contrast, very few buried seeds of E. nicaeensis emerged at all burial depths, and some buried seeds entered secondary dormancy. The different germination strategies of the two species may reflect their different habitats and dispersal modes: E. boetica grows in the lowlands on sandy soils, and its seeds are always buried after ant dispersal, whereas E. nicaeensis lives in montane regions on stony and compact soils, and its seeds may be frequently dispersed at soil surface, reducing the selective pressure for seeds to germinate after burial.
10 citations
TL;DR: This work investigates the genetic diversity within and among populations collected in the Alps and in the Arctic using 80 RAPD primers to improve the understanding of Ranunculus pygmaeus and Saxifraga cernua's glacial and postglacial history.
Abstract: Bauert M. R., Kalin M., Edwards P. J. and Baltisberger M. 2007. Genetic structure and phylogeography of alpine relict populations of Ranunculus pygmaeus and Saxifraga cernua. Bot. Helv. 117: 181–196. Ranunculus pygmaeus and Saxifraga cernua are arctic-alpine species with similar disjunct distributions: both occur as small, isolated relict populations in the Alps, while they are more widespread in the Arctic. To improve our understanding of their glacial and postglacial history, we investigated their genetic diversity within and among populations collected in the Alps and in the Arctic using 80 RAPD primers. We found only two genotypes of R. pygmaeus, one in the Alps and one in the Arctic. The absence of genetic diversity within each region is probably the consequence of postglacial colonization from a single source, followed by inbreeding in very small populations. In S. cernua, we found six genotypes among 11 populations in the Alps but no genetic variation within alpine populations. This limited genetic variation probably results from an extreme reduction and fragmentation of populations during successive glacial periods. In contrast, there was a high level of genetic variation both among and within all arctic populations of S. cernua. We suggest that this arose at least partly through the immigration of plants from multiple sources after the last glaciation. The higher genetic diversity of S. cernua compared to R. pygmaeus might also be related to their contrasting breeding systems: R. pygmaeus is an inbreeding diploid which propagates only by seeds, while S. cernua is a clonal polyploid which propagates mainly by vegetative means. Clonal growth, by prolonging the life span of a genotype, might contribute to the maintenance of genetic diversity under conditions which are difficult for sexual reproduction and seedling establishment.
9 citations
TL;DR: A morphometric study was performed on herbarium material from Slovenia to identify additional discriminative characters and to establish the distribution of taxa within the territory of Slovenia, showing a clear differentiation between L. campestris and the seven other taxa, which were only discriminated by combinations of several quantitative characters.
Abstract: Bacic T., Dolenc Koce J. and Jogan N. 2007. Luzula sect. Luzula (Juncaceae) in the South-Eastern Alps: morphology, determination and geographic distribution. Bot. Helv. 117: 75 – 88. Within the genus Luzula, the type section (Luzula sect. Luzula) is particularly variable and taxonomically diverse. Eight taxa of Luzula sect. Luzula occur in the Alps. While these taxa have distinct caryotypes, their identification based on morphological traits has remained problematic, and their geographic distribution is insufficiently known. A morphometric study was performed on herbarium material from Slovenia and neighbouring regions to identify additional discriminative characters and to establish the distribution of taxa within the territory of Slovenia. We measured 52 plant traits on 233 herbarium sheets and analysed the data with multivariate statistical techniques. Results showed a clear differentiation between L. campestris and the seven other taxa, which were only discriminated by combinations of several quantitative characters. In general, ripe fruits are required for a reliable determination. Four of the eight taxa are widespread in Slovenia: L. campestris and L. divulgatiformis in the lowlands (mostly 900 m), and L. multiflora across a broad altitudinal range (200–1900 m). Two taxa (L. divulgata and L. alpina) proved to be rare in Slovenia, and two taxa (L. sudetica and L. pallescens), previously reported for the area, were not confirmed. Distribution maps are presented for the six Slovenian taxa, and a new determination key is proposed for the eight Alpine taxa.
TL;DR: Kipfer et al. as discussed by the authors analyzed the composition of the soil seed bank of four beech forest stands and found that the seed banks mainly consisted of forest and ruderal species; most abundant were Juncus effusus, Carex sylvatica, Rubus spp. and Clematis vitalba.
Abstract: Kipfer T. and Bosshard A. 2007. Low seed bank of herb species suitable for grazing hampers the establishment of wood pastures in the Swiss lowlands. Bot. Helv. 117: 159 – 167. Controlled forest grazing is expected to yield benefits for biodiversity conservation, landscape quality, and in some cases also for land use economy. In the Swiss lowlands, first attempts are being made to reintroduce forest grazing in productive beech forests, but methodic experience is still limited. One main issue concerns the development of the vegetation after forest stands have been thinned to improve light conditions: Will grassland vegetation establish spontaneously? The present study analyses the composition of the soil seed bank of four beech forest stands. The seed bank density ranged from 1’244 to 28’651 seeds m−2. Seed banks mainly consisted of forest and ruderal species; most abundant were Juncus effusus, Carex sylvatica, Rubus spp. and Clematis vitalba. Seeds of grassland plants were restricted to a few species, and their abundance in the seed bank decreased rapidly with increasing distance from the forest edge. These results reveal that there is little potential for grasslands to develop spontaneously from the seed bank. The introduction of grassland species of local origin using the green hay method is therefore recommended to prevent soil degradation during the first years of grazing, to fulfil minimal biodiversity requirements and to lower the risk of an establishment of neophytes and other problematic plant species.
Journal Article•
TL;DR: Dank dieser seltenenGelegenheit konnte dieWassermoosflora des Rheinfalls fast 60 Jahre nach Jaag (1938) wieder einmal gr ndlich untersucht werden, andererseits die Ver nderungen seit den 1930er Jahren zu beurteilen.
Abstract: Der Rheinfall bei Neuhausen ist einer der grçssten Wasserf lle Europas. Seine Hçhe betr gt 23 m, seine maximale Breite 150 m. Die Wasserabflussmenge variiert innerhalb und zwischen den Jahren betr chtlich. ImZeitraum von 1959 bis 2005 betrug die grçsste gemessene Abflussmenge 1180 m/s (Mai 1999), die geringste 115 m/s (Februar 1963; http://www.hydrodaten.admin.ch/d/2288.htm). Der Rheinfall zog seit jeher viele Botaniker an, darunter auch Bryologen. Die ltesten uns bekannten Moosfunde vom Rheinfall stammen aus der Mitte des 19. Jahrhunderts von P.G. Lorentz, R. Gerwig, und L. Molendo (gem ss Datenbank des Naturr umlichen Inventars der SchweizerMoosflora NISM,Abfrage vom 13.8.2007). Die umfassendste Studie der Kryptogamenflora desRheinfallgebietes wurde 1938 vonO. Jaag publiziert. In ber 30 Exkursionen untersuchte er in den 1930er Jahren die beraus reiche Algen-, Flechtenund Moosflora des Rheinfalls. Viele aus bryologischer Sicht interessante Stellen des Rheinfalls sind nur bei Niedrigwasser zug nglich. Eine sehr geringe Abflussmenge wurde im Januar und Februar 2006 erreicht.Dank dieser seltenenGelegenheit konnte dieWassermoosflora des Rheinfalls fast 60 Jahre nach Jaag (1938) wieder einmal gr ndlich untersucht werden. Das Ziel war einerseits, eine aktuelle Artenliste derWassermoosflora zu erstellen, und andererseits, die Ver nderungen seit den 1930er Jahren zu beurteilen. Am 13.1.2006, bei einer Abflussmenge von 147 m/s, wurden alle gefahrlos zug nglichen Stellen auf der Schaffhauser Seite des Rheinfalls aufgesucht (Abb. 1). Dabei wurden f r den Damm und f r das restliche Gebiet (Plateau) je eine Liste der vorkommendenMoose angefertigt. Der Damm besteht aus k nstlich aufgeschichteten Kalkblçcken, das Plateau aus Kalkfelsplatten und -blçcken sowie einer kleineren betonierten Fl che. Diese Stellen sind die meiste Zeit berstrçmt. Die Artenlisten wurden mit denjenigen von Jaag (1938) f r die gleichen Fl chen verglichen. Bei Arten, die nur in einer der beiden Untersuchungen vorkamen, wurde gepr ft, ob sie von Jaag (1938) an anderen Stellen des Rheinfalls erw hnt wurden, bzw. ob sie 2006 in der