Spatial pattern in dry grassland communities of the Central Alps and its ecophysiological significance

The spatial pattern of species and microhabitats in a dry grassland mosaic in a Central Alpine valley was studied by a variance/mean analysis. In addition, the water-usage strategies of the dominant species were investigated. A significant correlation between species pattern and microhabitat pattern was found for the grass species. Grasses, with their homorhizal root system, are unable to exploit sources of water in deep rock crevices, and are therefore dependent on the water-storage capacity of the particular soil layer. Dwarf shrubs and succulents (with one exception) are independent of this latter water source. The common chamaephytes exhibit contradictory types of stomatal behaviour.Artemisia alba is characterized by a water-conservation strategy, whereasHelianthemum nummularium spp.obscurum andTeucrium chamaedrys are not. The careful usage of the water reserves byArtemisia alba would seem to represent an adaptation to dry grassland conditions. The other dwarf shrubs, in contrast, with their ‘water-wasting’ strategy, have a root system like that ofArtemisia and are unable to compensate for the higher rate of water loss. Thus, the observed ecophysiological differences cannot be interpreted as being ‘different solutions to the same problem’, as a result of divergent evolution. Two alternative interpretations are: a) the stomatal behaviour of the chamaephytes is a characteristic of their respective genera and which is not particularly adaptive here; b) the dry grasslands studied are the remnants of a former vegetation type, which had a low level of competition.     

Genetic diversity of the expansive grass Brachypodium pinnatum in a changing landscape: Effect of habitat age

Perennial grasses constitute a major group of species showing a dramatic decline of biodiversity in successional plant communities. Using AFLP markers, we examined 12 populations of the expansive grass Brachypodium pinnatum differing in habitat age (30–50, ca. 100 and >300 years old) in order to determine whether clonal diversity of populations, genetic variation, and the relative importance of clonal propagation versus sexual reproduction change with grassland age. Five AFLP primer combinations gave a total of 517 bands, 79% of which were polymorphic. 314 different multilocus lineages were distinguished among the 453 samples analyzed. The number of genotypes (G) and clonal richness (R) decreased with habitat age, while the distribution of the frequency of genets changed from many clones of similar size to dominance by one or a few large clones. We consider these results to give evidence of significant role of sexual reproduction in the early phases of colonization and prevalence of clonal growth and competitive exclusion of less adapted genotypes in the later ones. However, habitat age had only marginal effect on genetic diversity, as percentage of polymorphic loci (PPL) within all the populations analyzed was similar, viz. 38.6–43.5%.     

Herbivore-induced expansion of <Emphasis Type="Italic">Helianthemum nummularium</Emphasis> in grassland–scrub mosaic vegetation: circumstantial evidence for zoochory and indirect grazing impact

Extensive grazing often has a strong influence on the structure and composition of herbaceous plant communities with increasing population sizes for some species and decreasing presence in others. Herbivores affect plant communities directly by selective grazing of plant species, and indirectly by either epizoochory or endozoochory. Helianthemum nummularium is considered an increasing species because its distribution increased after the introduction of large, free-ranging grazers in at least two coastal dune grassland areas in Belgium. However, its seeds lack any obvious adaptations for epizoochory, and direct observations of plant/seed consumption are scarce. Through field and lab experiments, we assessed the dispersal ability of H. nummularium via endozoochory and epizoochory. In a differentiated grazer exclusion experiment, evidence was found that plants are grazed by large domestic ungulates and small wild herbivores although these incidences were rare. Direct endozoochory evidence remained scarce. No seeds were found germinating in field-collected dung, and only few seedlings emerged following a seed feeding experiment. However, once deposited, we found higher growth rates when seeds were mixed with dung and decreased establishment success when seeds were sown in combination with competitively superior species. Epizoochory was plausible because both fur and hooves of cattle and horses were potentially capable of contributing to the transport of H. nummularium seeds. We conclude that herbivores play a role in seed dispersal, while their selective grazing behaviour most probably creates an appropriate environment for Helianthemum establishment and maintenance.     

Some autecological characteristics of early to late successional tree species in Venezuela

The breadth of the continuum concept of strategy with respect to succession was tested on 21 tree and shrub species common in either unlogged or logged stands, respectively, in the Forest Reserve of Caparo, Venezuela, by examining morphological, physiological and population characteristics. Based on a preliminary abundance analysis, `early', `mid' and `late' successional species as well as `generalists' were distinguished. Early successional species, i.e. Ochroma lagopus, Heliocarpus popayanensis and Cecropia peltata were similar in many autecological aspects, e.g. monolayered leaf arrangement, orthotropic architectural models, no adaptive reiteration, clumped distribution, but differed in gap association and distribution along a drainage gradient. Mid-successional species established themselves both in large and small gaps (> 300 m[sup2 ]; 80–300 m[sup2 ]) and showed a clumped to regular distribution pattern in logged areas; they exhibited more diverse crown and leaf characteristics than early successional species. Late successional species established themselves only in small gaps and understorey, and showed a regular spatial pattern in undisturbed areas. All late successional species displayed architectural models with plagiotropic lateral axes and showed a multilayered leaf arrangement. Adaptive reiteration was a common feature of late successional species which could be further subdivided into large, medium-sized and small trees, indicating different light requirements at maturity. Generalists were common treelet and shrub species in both disturbed and undisturbed sites where they are also capable of completing their life cycle. The light compensation point (LCP) of an individual plant was strongly influenced by its crown illuminance. Large late successional species showed the widest range of LCP values, reflecting the increasing light availability with increasing height in mature forest. On the basis of many autecological characteristics, it was found (i) that there is in fact a continuum of species strategies with respect to succession even among early and mid-successional species and (ii) that the latter group of species showed the widest breadth of autecological traits, reflecting the heterogeneous environment in which they establish and mature.     

Remains of grasses found with the Neolithic Iceman “Ötzi”

The plant remains from the discovery site of the Iceman include a large quantity of grass, from which parts of his clothing were also made. His cape consists of bundles of Brachypodium pinnatum tied with Tilia bast fibres, and the hay used as insulating material in his shoes consists of several species, such as Avenella flexuosa, Avenula versicolor/pubescens, Festuca spec., Nardus stricta and Brachypodium pinnatum. Most probably, these grasses were collected in subalpine matt-grass communities. Additionally, the birch bark vessel found beside the body contained pieces of Molinia caerulea. Grass fragments were evenly distributed all over his equipment as well as in the ice of the gully in which the Iceman was embedded. This implies that the ice in the gully thawed at least once between 3300 and 800 b.c. and the find assemblage was floating in the melt water.     

Diversity,variability and habitat characteristics of the communities dominated by Sesleria species (Poaceae) in the Western Carpathians

This study provides a view of vegetation types dominated by Sesleria species in the Western Carpathians (Sesleria caerulea, S. heufleriana, S. tatrae, and S. uliginosa). We also took into account characteristics/traits such as plant life forms, autochthonous status, endemism, and ploidy level occurring within each relevé in our data set. Altitude and Ellenberg indicator values derived for each relevé were considered as well. Eight vegetation types/formations/habitats were recognized in a data set of 942 phytosociological relevés: (1) synanthropic vegetation, (2) rock fissures and screes, (3) alpine grasslands and heaths, (4) mesic grasslands and pastures, (5) springs and fens, (6) forests, (7) xerophilous shrubland, and (8) high-mountain scrubs (krummholz). Results corroborated and clearly emphasized that Sesleria caerulea has the widest ecological amplitude of all studied species because the species occurred among all studied vegetation types. Sesleria tatrae was present only in several vegetation types occurring from montane to alpine vegetation belts in the highest mountains. Sesleria heufleriana and S. uliginosa were recorded only in low-altitude areas. The difference between them lies mainly in the dampness of each locality. Sesleria heufleriana was frequently found in xerophilous communities, whereas S. uliginosa preferred humid habitats of springs and fens.     

Isoteuflidin,a neo-clerodane diterpenoid from Teucrium chamaedrys,and revised structures of teucrins F and G

A new neo-clerodane diterpenoid, isoteuflidin, was isolated from the aerial part of Teucrium chamaedrys. Its structure, 15,16-epoxy-3β-hydroxy-19     

The relationship between tree biodiversity and biomass dynamics changes with tropical forest succession

Theory predicts shifts in the magnitude and direction of biodiversity effects on ecosystem function (BEF) over succession, but this theory remains largely untested. We studied the relationship between aboveground tree biomass dynamics (Δbiomass) and multiple dimensions of biodiversity over 8–16 years in eight successional rainforests. We tested whether successional changes in diversity–Δbiomass correlations reflect predictions of niche theories. Diversity–Δbiomass correlations were positive early but weak later in succession, suggesting saturation of niche space with increasing diversity. Early in succession, phylogenetic diversity and functional diversity in two leaf traits exhibited the strongest positive correlations with Δbiomass, indicating complementarity or positive selection effects. In mid‐successional stands, high biodiversity was associated with greater mortality‐driven biomass loss, i.e. negative selection effects, suggesting successional niche trade‐offs and loss of fast‐growing pioneer species. Our results demonstrate that BEF relationships are dynamic across succession, thus successional context is essential to understanding BEF in a given system.     

Root and leaf attributes accounting for the performance of fast- and slow-growing grasses at different nutrient supply

Despite their difference in potential growth rate, the slow-growing Brachypodium pinnatum and the fast-growing Dactylis glomerata co-occur in many nutrient-poor calcareous grasslands. They are known to respond differently to increasing levels of N and P. An experiment was designed to measure which characteristics are affected by nutrient supply and contribute to the ecological performance of these species. Nutrient acquisition and root and shoot traits of these grasses were studied in a garden experiment with nine nutrient treatments in a factorial design of 3 N and 3 P levels each. D. glomerata was superior to B. pinnatum in nutrient acquisition and growth in all treatments. B. pinnatum was especially poor in P acquisition. Both species responded to increasing N supply and to a lesser extent to increasing P supply by decreasing their root length and increasing their leaf area per total plant weight. D. glomerata showed a higher plasticity. In most treatments, the root length ratio (RLR) and the leaf area ratio (LAR) were higher for D. glomerata. A factorization of these parameters into components expressing biomass allocation, form (root fineness or leaf thickness) and density (dry matter content) shows that the low density of the biomass of D. glomerata was the main cause for the higher RLR and LAR. The biomass allocation to the roots showed a considerable plasticity but did not differ between the species. B. pinnatum had the highest leaf weight ratio. Root fineness was highly plastic in D. glomerata, the difference with B. pinnatum being mainly due to the thick roots of D. glomerata at high nutrient supply. The leaf area/leaf fresh weight ratio did not show any plasticity and was slightly higher for B. pinnatum. It is concluded, that the low density of the biomass of D. glomerata is the pivotal trait responsible for its faster growth at all nutrient levels. It enables simultaneously a good nutrient acquisition capacity by the roots as well as a superior carbon acquisition by the leaves. The high biomass density of B. pinnatum will then result in a lower nutrient requirement due to a slower turnover, which in the long term is advantageous under nutrient-poor conditions.     

Elicited Teucrium chamaedrys cell cultures produce high amounts of teucrioside,but not the hepatotoxic neo-clerodane diterpenoids

Teucrium chamaedrys, one of the most common and investigated species of the genus Teucrium, has been used for centuries in traditional medicine for many purposes. Its phytochemical components comprise, among others, phenylethanoid glycosides (PGs) and neo-clerodane diterpenoids. Several reports have demonstrated a wide range of beneficial biological and pharmacological activities of the phenylethanoid components, while the diterpenes were shown to be strongly hepatotoxic. In this work, in vitro cultures were established from leaf explants of T. chamaedrys. Both solid (callus) and liquid (cell suspension) cultures maintained the capacity to produce PGs, with teucrioside (TS) representing the most abundant one. Cell suspensions had a lower TS content than that found in leaf extracts, but higher than that of calli. An NMR-based metabolomics approach was used to compare the product profile of intact plants vs. cell suspension cultures, and results showed that neo-clerodane diterpenes, present in the intact plant, were not detected in cell cultures. Several elicitors were supplied to cell cultures with the aim of increasing TS production, and elicitation was tested at different growth phases and by exposing cells for different periods. Methyl jasmonate and fungal mycelia from Trichoderma viridae and Fusarium moniliforme were able to significantly increase TS production if supplied at the early-exponential growth phase for 24 h. Based on the proposed link between proline and the phenylpropanoid pathways, proline accumulation in cell cultures was followed throughout a 14-day culture period, showing that it strictly reflected that of TS production. Moreover, exogenously supplied proline, and its analogue hydroxyproline, turned out to be very effective in increasing teucrioside production.     

Secondary succession in a fallow central European wet grassland

This long-term study (23 yr) aims at specifying the characteristic features of secondary progressive successions in abandoned wet eutrophic grasslands as a precondition for better understanding causal relationships and improving the predictability of successions on such habitats. The vegetation of inundated fen grasslands (Calthion) at the lower course of the river Wümme near Bremen (Northwest Germany) was studied annually on three permanent plots (each 10×10 m²) where hay making had ceased in 1983, 1985 and 1992, respectively. In the initial succession phase of three to five years a fast increase of tall-growing, rhizomatous, deciduous reed species (e.g. Phalaris arundinacea) occurred. This strongly changed vegetation structure and within-canopy light climate, which was the reason for the strong decrease in species diversity. Rhizomes are hypothesized to be a key factor of high competitiveness in abandoned wet grasslands because this organ combines multiple advantageous functions: low-risk vegetative propagation, nutrient storage and nutrient re-allocation between above- and below-ground plant organs, all these functions allowing for a gradual build-up of a high biomass. Extinct grassland species (e.g. Senecio aquaticus) represent a contrasting set of plant traits such as small stature, short lifespan, prevailing generative reproduction and evergreen leaves. The subsequent succession phase commencing about five years after mowing was ceased was characterized by persistence of the established reed vegetation, which prevented tree colonisation until today. Secondary successions in abandoned wet eutrophic grasslands can be predicted on the level of plant communities and functional species groups considering changes in the habitat (esp. light climate), the presence of reed species with a specific set of plant traits in the “Initial Floristic Composition” and their potentially high competitive vigour.     

Field observed relationships between biodiversity and ecosystem functioning during secondary succession in a tropical lowland rainforest

The relationship between biodiversity and ecosystem functioning (BEF) is one of the most concerned topics in ecology. However, most of the studies have been conducted in controlled experiments in grasslands, few observational field studies have been carried out in forests. In this paper, we report variations of species diversity, functional diversity and aboveground biomass (AGB) for woody plants (trees and shrubs) along a chronosequence of four successional stages (18-year-old fallow, 30-year-old fallow, 60-year-old fallow, and old-growth forest) in a tropical lowland rainforest recovered after shifting cultivation on Hainan Island, China. Fifty randomly selected sample plots of 20 m × 20 m were investigated in each of the four successional stages. Four functional traits (specific leaf area, wood density, maximum species height and leaf dry matter content) were measured for each woody plants species and the relationships between species/functional diversity and AGB during secondary succession were explored. The results showed that both plant diversity and AGB recovered gradually with the secondary succession. AGB was positively correlated with both species and functional diversity in each stage of succession. Consistent with many controlled experimental results in grasslands, our observational field study confirms that ecosystem functioning is closely related to biodiversity during secondary succession in species rich tropical forests.     

黔中喀斯特山区植物功能性状的变异与关联

认识植物功能性状随演替进展的变化规律和不同性状之间的关系, 有助于从功能生态学的角度来理解群落演替。该文调查了位于贵州省中部的普定县喀斯特山区26个样方的物种组成, 这些样方分别处于灌丛、落叶阔叶林、落叶常绿混交林3个演替阶段; 测量了分布于该区域的82种木本植物的3个功能性状值(叶面积、比叶面积、最大高度); 根据物种在样方中的多度加权计算得到26个样方的性状平均值, 在此基础上分析了随演替进展植物功能性状在群落水平上的变异格局和不同性状之间的相关性; 采用性状梯度分析法分析了各阶段优势物种的功能性状在群落间(β组分)和群落内(α组分)的变异格局及相关性。结果表明: 1)沿灌丛→落叶阔叶林→落叶常绿混交林这一演替顺序, 群落平均叶面积和平均高度逐渐增加, 而群落平均比叶面积则逐渐变小; 2)就群落平均性状值而言, 叶面积与最大高度呈较强的正相关关系, 最大高度与比叶面积、叶面积与比叶面积均呈较强的负相关关系; 3)物种功能性状的α组分之间没有显著的相关关系, 而β组分之间相关性显著。这说明: 随演替的进展, 群落优势物种对环境的适应策略由高速生长转向提高资源利用效率, 而同一群落内共存的物种采取不同的性状组合来适应共同的群落环境。     

Coastal heathland succession influences butterfly community composition and threatens endangered butterfly species

Succession has a strong influence on species diversity and composition of semi-natural open terrestrial ecosystems. While several studies examined the effects of succession on butterflies in grassland and forest ecosystems, the response of heathland butterflies to succession had not been investigated so far. To address this issue we sampled butterfly abundance and environmental parameters on the Baltic island of Hiddensee (NE Germany) along a gradient of coastal heathland succession from grey dunes to birch forest. Our results provide evidence that succession of coastal heathland has a strong influence on butterfly diversity, abundance, and species composition. Thereby grass and tree encroachment present the main threats for heathland butterflies. Diversity and abundance of butterflies were highest in shrub-encroached heath directly followed by early stages of coastal heathland succession (dwarf-shrub heath, grey dune). Both observed threatened species (Hipparchia semele, Plebeius argus) were negatively affected by succession: abundance decreased with increasing vegetation density (both species) and grass cover (P. argus); consequently, the two later successional stages (shrub, birch forest) were not occupied. Our findings highlight the importance of the preservation of early stages of coastal heathland succession for endangered butterfly species. For coastal heathland management we therefore suggest to maintain early successional stages by sheep grazing, mowing or, in case of high nutrient contents, intensive techniques such as sod-cutting or choppering. To a lower extend shrub-encroached sites should also be present, which might be beneficial for overall species richness.     

Fifty years vegetation development of a xerothermic calcareous grassland in Central Europe after heavy disturbance

Fifty years ago on the south-facing slope of a limestone hill 4 km NE of Göttingen (Germany) a small plot of 4 m² size was chosen in a xerothermic calcareous grassland (Mesobromion alliance) for investigation. The formerly grazed slope was abandoned a few years prior to the study, but in 1987 intermittent grazing started again. The mean annual temperature in Göttingen (1953–2003) was 8.8 °C on the average; the annual mean increased by 1.1 °C during the study period. Mean annual precipitation amounted to 642 mm (393–1093 mm). The mean monthly precipitation during summer (April–August) varied in the range between 29 and 101 mm. In the years 1953–2003 the presence of species was recorded annually in 400 subplots (100 cm² each). In part of this time also the amount of bare soil within the plot was recorded, and standing crop and the nitrogen contents in leaves of Bromus erectus were measured in the immediate surrounding of the plot.In fall 1953 the vegetation was removed completely in half of the plot, in the other half the two dominant grasses Bromus erectus and Brachypodium pinnatum were left. The differences between the two halves vanished already after 2 years (starting phase 1953–1955). Thus, only results concerning the plot as a whole are reported here. During the investigation three periods could be distinguished. After the starting phase in period I (1955–1986) total presence, presence of the most important species, species richness, number of endangered species, diversity and evenness increased. In this way the grassland regenerated after the heavy disturbance, and a dense, species-rich vegetation formed. Only a few species showed maximum values already within the first 10 years and faded out later.Period II (1987–1997) spanned 10 years of grazing. During this time total presence, presence of many important species, species richness, number of endangered species, diversity and evenness decreased, whereas areas with bare soil increased. Only two species showed maximum values during this phase, and just one new species invaded (Lolium perenne). During this period a more open type of grassland was formed. Period III (1998–2003) spanned 5 years without grazing and only one grazing year (2002). Here, a partial regeneration of a more closed grassland took place with traits similar to period I.Several phenomena occurred continuously through all three periods. Bromus erectus always was the dominating species. Nevertheless, proportions of graminoids (in % total presence) were lowered, and the proportion of herbs increased. The ratio Bromus erectus/Brachypodium pinnatum was determined mainly by Brachypodium. Seedlings of woody plants were always present, but in most cases survived only one summer. Shrubs did not settle inside the plot, although small bushes developed in the immediate surrounding. In summary the 50-year process can be described as a slow recovery of a calcareous grassland after very heavy disturbance, modified by intermittent grazing, without formation of shrub vegetation.     

Conservation genetic assessment of four plant species in a small replica of a steppe ecosystem &gt;30 years after establishment

To counter species loss living ex situ collections in botanic gardens became important elements of robust conservation programs. Several limitations, problems, and risks associated with living ex situ collections have been reported such as appropriate cultivation management to maintain genetic diversity and stochastic effects in small isolated populations in artificial habitats. However, not all small and isolated populations exhibit these predicted genetic changes. In a multi-species in situ/ex situ comparison of sand dune steppe- and grassland vegetation >30 years after the ex situ population establishment, we compared four different species’ population genetic diversities (Alyssum montanum ssp. gmelinii, Gypsophila fastigiata, Helianthemum nummularium ssp. obscurum, Onosma arenaria) by means of ISSR. We observed different species-specific genetic responses to quite similar abiotic selective forces concerning different neutral genetic diversities of wild versus botanic garden populations. The genetic divergence was kept relatively low in two of the four investigated species between the model steppe plant community within the botanic garden where human interference was kept at a minimum and the wild population. However, the moderate genetic divergence of the two other species kept under the same conditions highlights the importance of species-specific intrinsic responses and stochastic effects to ecosystem changes and provides data on population genetic dynamics in small and isolated populations. This contributes to further improve recommendations on how to best conserve endangered plant species in ex situ environments (cultivation in near nature-like replicas of the original site with as little human inference as possible over only certain periods of time, >30 years).     

Functional traits associated with plant colonizing and competitive ability influence species abundance during secondary succession: Evidence from subalpine meadows of the Qinghai–Tibetan Plateau

It is widely recognized that colonists and competitors dominate early and late succession, respectively, with selected species having different colonizing and competitive abilities. However, it remains unknown whether colonizing and competitive ability can determine species abundance directly over succession. The data for five key functional traits were collected (photosynthesis rate, leaf turgor loss point, leaf proline content, seed mass, and seed germination rate), which are direct indicators of plant competitive and colonizing abilities including growth, drought and cold stress resistance, dispersal, and seed dormancy. Here, we tested the effects of colonizing and competitive abilities on species abundance, by employing a linear mixed‐effects model to examine the shifts in the relationship between species abundance and these five colonization and competition‐related traits in species‐rich subalpine secondary successional meadows (at 4, 6, 10, 13 years of age, and undisturbed, respectively) of the Qinghai–Tibetan Plateau. The abundant species at the early‐successional meadows tend to have high photosynthetic rate, high leaf proline content, low seed mass, and seed germination rate for having high colonizing ability, but low competitive ability. By contrast, late‐successional communities tend to be dominated by species with high competitive ability, but low colonizing ability, indicated by large seeds, high seed germination rate, low photosynthetic rate, and leaf proline content. The observed directional shifts in the relationships between traits (photosynthetic rate, leaf proline content, seed mass, and seed germination rate) and abundance with successional age, bring two new understandings of community assembly during succession of subalpine meadows in the Qinghai–Tibetan Plateau. First, it discloses that the differences in species abundance over succession can be directly attributed to differences in colonizing and competitive abilities of different species. Second, it expands the effects of multiple life historical differences including growth, resource competitive ability, cold stress resistance, dispersal, and seed germination strategy, represented by functional traits on community assembly along succession, that is, from the species to the community level.     

Comparative study of genotoxicity and antimutagenicity of methanolic extracts from Teucrium chamaedrys and Teucrium montanum in human lymphocytes using micronucleus assay

Since Teucrium chamaedrys and Teucrium montanum are the most popular plants used in the treatment of many diseases, we evaluated genotoxic potential of their methanolic extracts on cultured human peripheral blood lymphocytes (PBLs) using cytokinesis-block micronucleus (MN) assay. Cultures were treated with four concentrations of both plants (125, 250, 500 and 1,000 μg/ml), both separately and in combination with mitomycin C (MMC). The results revealed that extract of T. chamaedrys administered at the tested concentrations did not significantly affect the mean MN frequency in comparison to untreated cells. Methanolic extract of T. montanum increased the mean MN frequency in PBL at the tested concentrations, but significantly only at the concentration of 1,000 μg/ml. In all tested concentrations, the extract of T. chamaedrys significantly reduced the MMC-induced MN frequency, in a dose dependent manner (r = − 0.687, p < 0.01). The extract of T. montanum decreased the MMC-induced MN frequency at the tested concentrations, but statistically only at 125 μg/ml. Both extracts administered alone did not significantly affect the nuclear division index (NDI) at the tested concentrations. In the combined treatments with MMC, the extract obtained from T. chamaedrys in the concentrations of 500 and 1,000 μg/ml significantly decreased NDI values in comparison to MMC-treated cells alone, while the extract of T. montanum significantly decreased NDI at all tested concentrations. Both extracts nonsignificantly decreased NDI at all tested concentrations in comparison to untreated cells. Our results suggest the important function of T. chamaedrys extract in cancer therapy, this methanolic extract may prevent genotoxic effects of chemotherapy in PBLs.     

Leaf press juice from Bryophyllum pinnatum (Lamarck) Oken induces myometrial relaxation

Aims

The use of preparations from Bryophyllum pinnatum (Lamarck) Oken (Kalanchoe pinnata (Lamarck) Persoon) in tocolysis is supported by clinical evidence. We studied here the effect of B. pinnatum leaf press juice and its chemical fractions on the response of human myometrial strips. No data are available if the influence on myometrial strips of the juice differs from that of its components in the chemical fractions, in order to increase the pharmacological effect.

Methodology

In vitro study to test the effect of repeated addition of B. pinnatum leaf press juice (BPJ) and its chemical components in several dilutions (undiluted, 1-10%) on myometrium strips hang up in a myograph chamber. Chemical analysis is including HPLC, MPLC with Sephadex LH-20 and TLC.

Results

All test solutions are inhibiting contractility by reducing the amplitude and the area under the curve (AUC) of the contractions. Undiluted BPJ and its undiluted chemical fraction 4 are reducing most effective these two parameters: the amplitude was at 78% of the baseline (95% CI (77-89); p < 0.05) at the second addition of the BPJ and at 70% (95% CI (50-90); p < 0.05) of the first addition of fraction 4; the AUC was at 82% (95% CI (69-95); p < 0.05) of the baseline at the first addition of the press juice and at 51% (95% CI (27-74); p < 0.05) at the first addition of fraction 4. The BPJ decreased amplitude and AUC significantly faster and increased frequency significantly faster than the control. Fractions could be tentatively assigned to bufadienolids, flavonoids and cinnamic acids. Fraction 4, accounted for flavonoids, increased the frequency of the contractions most effectively: 557% of the baseline (95% CI (316-797); p < 0.05) at the first addition.

Conclusion

Leaf juice of B. pinnatum and its flavonoid fraction are most effective in relaxing myometrial strips by inducing frequency.     

Plant strategies and secondary succession on Brittany heathlands after severe fire

Abstract. Plant succession on heathlands subjected to major fire disturbance and humus burn in 1976 was studied over twelve years following burning. Life history strategies of principal heathland species are described with reference to concepts outlined by Grime (1979) and Whittaker & Goodman (1979). Heathlands and closely related communities are characterised by dominance of speciestolerant of physical stress (‘S’ strategists) whereas species which colonise disturbed sites are closer to rude-rals (‘R’ strategists). After severe burning three main successional patterns were identified. They depend on water and nutrient availability relative to temporal population dynamics. Recovery of heathland is often retarded due to monospecific dominance, e.g. of Polytrichum commune, Molinia caerulea and Betula pubescens. These patterns of secondary succession illustrate the inhibition model advanced by Connell & Slatyer (1977).