Search

This study addresses the question of how changing the mowing regime influences the floristic composition and floristic diversity of grasses in an experimental lowland meadow. The study location is Bia?owie?a Forest, NE Poland. To achieve the aim we used phytosociological data from long-term studies in Bia?owie?a Forest on the course of secondary succession. The relationship between the biodiversity of grasses and type of mowing was determined using statistical analysis. Changes in the dominance and frequency of individual grass species have occurred during the last 28 years of observations. The analysis of floristic similarity demonstrated a turnover of species between the individual years of observation. Principal component analysis showed that the change in mowing method resulted in a change of the species composition, cover, and domination. However, differences in the intensity of disturbance level were rather small (one cut yearly by scythe, by sickle bar mower, and by trimmer), and changes in floristic composition were also moderate in most years. During the initial years (1984?1990), Dactylis glomerata, Agrostis gigantea, and Anthoxanthum odoratum dominated. After 1990, Arrhenatherum elatius and Holcus lanatus spread and took over, with Trisetum flavescens joining them later. Between 2008 and 2012 the cover of Dactylis glomerata increased more than two times. The reasons for the floristic transformations were changes in the management mode, e.g., the transition from mowing by scythe (medium disturbance) to mechanized mowing, first by sickle bar mower (strong disturbance) and then by trimmer (weak disturbance).

Our study on the dependence of the mode and degree of cultivation of the grassland on the rate of mycorrhizal development in the species Alopecurus pratensis and Trisetum flavescens suggests that the degree of cultivation, and mainly the amount of available food resources in the soil, influence the development of the endophyte in the roots of the plant hosts.

In the present study, we investigated plant communities with Yellow Oat Grass (Trisetum flavescens (L.) Pb.) in the submontane and montane regions of Slovenia. In 2005-2007 ninety-one relevés were collected by using the standard procedure of the Braun-Blanquet approach. Relevés were analysed with multivariate analysis and classified within two associations: Astrantio-Trisetetum (Polygono-Trisetion) and the Pastinaco-Arrhenatheretum (Arrhenatherion). Management practices, soil conditions and altitude were found to be significant factors for a further subdivision of both associations. Within the Astrantio-Trisetetum association three subassociations could be distinguished: -typicum, -buphthalmetosum and -trollietosum, and subassociations -typicum, -medicagetosum lupulinae, as well as -lolietosum subass. nova in the Pastinaco-Arrhenatheretum. The floristic composition and ecological characteristics of these plant communities are described and their implications for grassland conservation in Slovenia are discussed. V članku predstavljamo rezultate raziskave vegetacije travišč s prevladujočim rumenkastim ovsencem (Trisetum flavescens) v submontanskih in montanskih predelih Slovenije. V letih 2005-2007 smo popisali 91 vegetacijskih sestojev po standardni Braun-Blanquetovi metodi. Na osnovi multivariatnih analiz smo uvrstili travišča v dve asociaciji, in sicer v asociacijo Astrantio-Trisetetum (zveza Polygono-Trisetion) in asociacijo Pastinaco-Arrhenatheretum (zveza Arrhenatherion). Nadaljnja členitev na nižje sintaksonomske enote obeh asociacij je pogojena predvsem s stopnjo intenzivnosti upravljanja s travišči, z različnimi edafskimi razmerami in nadmorsko višino. Tako ločimo v asociaciji Astrantio-Trisetetum naslednje sintaksone: subasociacije -typicum, -buphthalmetosum in -trollietosum, v asociaciji Pastinaco-Arrhenatheretum pa: -typicum, -medicagetosum lupulinae in -lolietosum subass. nova. Predstavljene so floristična sestava asociacij, njune ekološke značilnosti in varstveni vidiki obravnavanih travišč.

A long-term fertilizer experiment (the Rengen Grassland Experiment, RGE) was established in 1941 in the Eifel Mountains of Germany on low productive grassland naturally dominated by Calluna vulgaris and Nardus stricta. Six treatments combinations of Ca, N, P, and K fertilizer were applied annually: an unfertilized control, Ca, CaN, CaNP, CaNP–KCl, and CaNP–K2SO4. In mid-June 2005, plant cover was visually estimated and sward height was measured aiming to detect changes in floristic composition caused by long-term fertilization. Calculated by redundancy analysis (RDA), the effect of treatment was found to be a significant predictor of sward structure in the experimental area and explained 62% of cover data variability. The largest difference in vegetation structure and composition was between the treatments without and with P application. Briza media was the dominant short grass in the control, Ca, and CaN treatments. Lathyrus linifolius was the dominant legume in the control and Carex panicea was dominant in the CaN treatment. Among treatments with P application, plant species composition was similar with tall grasses such as Alopecurus pratensis, Arrhenatherum elatius, and Trisetum flavescens dominating in the sward. Sward heights were lowest in treatments without P addition in contrast to tall canopies in the P fertilized treatments. Cover of the moss layer was continuously developed in treatments without P application only and was negatively correlated with sward height as was species richness of vascular plants. Long-term fertilization caused significant diversification of plant communities. Species indicative of low productivity grasslands (short grasses, orchids, and sedges) survived in the CaN treatment but not in plots with P or K fertilizer. It was often thought that N enrichment is detrimental to vascular plant richness. However, the RGE shows that this is not necessarily so if N application is not accompanied by another limiting nutrient like P. # 2007 Elsevier B.V. All rights reserved.

Summary Seven plant species were exposed in open-top chambers to four levels of ozone (O 3 ) during two growing seasons and screened for treatment effects on the fast chlorophyll a (Chl) fluorescence transient kinetics of dark-adapted leaves, and on the fluorescence signals obtained from the same leaves in illuminated steady-state. The aim was to identify the nature of O 3 effects on PSII, and to determine inter-specific differences. In dark-adapted leaves, O 3 caused a reduction in variable fluorescence (F V : F 0 ), indicating an overall reduction in the efficiency of primary photochemistry. A large increase in excitation energy dissipation per active reaction centre (DI 0 /RC) and a smaller increase in the trapping rate of excitons (TR 0 /RC), showed that a fraction of the reaction centres was inactivated while the rest sustained full functionality. The magnitude of the effect increased in the order of Bromus erectus Centaurea jacea Trisetum flavescens Rumex obtusifolius Plantago lanceolata Trifolium pratense Knautia arvensis . The inter-specific variability in PSII responses could not be explained solely by specific differences in modelled O 3 uptake by the leaves. Visible leaf injury was not related to changes in fluorescence emission. In illuminated steady-state, O 3 sensitivity was most expressed in the change in quantum yield of photosynthetic electron transport (Φ PSII ). The ranking of species differed from the ranking obtained in dark-adapted leaves. These results suggest that the mechanistic basis for O 3 effects on PSII is similar in all species, but that inter-specific differences exist in the magnitude of change which cannot be explained solely by different O 3 uptake rates. The observed changes in fluorescence signals are not O 3 -specific.

To test inter- and intraspecific variability in the responsiveness to elevated CO2, 9–14 different genotypes of each of 12 perennial species from fertile permanent grassland were grown in Lolium perenne swards under ambient (35 Pa) and elevated (60 Pa) atmospheric partial pressure of CO2 (pCO2) for 3 years in a free air carbon dioxide enrichment (FACE) experiment. The plant species were grouped according to their functional types: grasses (L. perenne, L. multiflorum, Arrhenatherum elatius, Dactylis glomerata, Festuca pratensis, Holcus lanatus, Trisetum flavescens), non-legume dicots (Rumex obtusifolius, R. acetosa, Ranunculus friesianus), and legumes (Trifolium repens, T. pratense). Yield (above a cutting height of 4.5 cm) was measured three times per year. The results were as follow. (1) There were highly significant differences in the responsiveness to elevated pCO2 between the three functional types; legumes showed the strongest and grasses the weakest yield increase at elevated pCO2. (2) There were differences in the temporal development of responsiveness to elevated pCO2 among the functional types. The responsiveness of the legumes declined from the first to the second year, while the responsiveness of the non-legume dicots increased over the 3 years. During the growing season, the grasses and the non-legume dicots showed the strongest response to elevated pCO2 during reproductive growth in the spring. (3) There were no significant genotypic differences in responsiveness to elevated pCO2. Our results suggest that, due to interspecific differences in the responsiveness to elevated pCO2, the species proportion within fertile temperate grassland may change if the increase in pCO2 continues. Due to the temporal differences in the responsiveness to elevated pCO2 among species, complex effects of elevated pCO2 on competitive interactions in mixed swards must be expected. The existence of genotypic variability in the responsiveness to elevated pCO2, on which selection could act, was not found under our experimental conditions.

Es werden zwei neue Arten beschrieben: Pastinaca argyrophylla sp. nov. und Linaria brachyphylla sp. nov. Neu fur die Flora Bulgariens sind die Art Gagea chrysantha (JAN.) SCHULTES et SCHULTES fil. sowie drei Unterarten: Avena barbata POTT. ex LINK subsp. wiestii (STEUD.) TZVEL., Trisetum flavescens (L.) BEAUV. subsp. tatricum CHRTEK und Peucedanum vittijugum BOISS. subsp. vittijugum. Fur die ubrigen Taxa werden neue Fundorte in Bulgarien mitgeteilt. The author reports two species new for the science: Pastinaca argyrophylla sp. nov. and Linaria brachyphylla sp. nov.; one species new for the Bulgarian flora — Gagea chrysantha (JAN.) SCHULTES et SCHULTES fil. and three subspecies also new for the Bulgarian flora: Avena barbata POTT. ex LINK subsp. wiestii (STEUD.) TZVEL., Trisetum flavescens (L.) BEAUV. subsp. tatricum CHRTEK and Peucedanum vittijugum BOISS. subsp. vittijugum. New localities in Bulgaria are pointed out for the remaining taxa.

Summary Trisetum favescens , a grass which causes tissue calcification in cattle, was tested for vitamin D-like activity in bioassays using rats and Japanese quail. In both tests, an activity between 3 and 4 I. U. per gram of dry matter was found. An extraction and purification procedure followed by mass spectrometric analysis revealed that a considerable amount of cholecalciferol, the «animal vitamin D», does occur in T. flavescens . Distribution studies showed high concentrations in young, leafy parts and low levels in stems, flowers, seed and roots. Five different breeds of T. flavescens were similar in vitamin Dactivity. T. flavescens grown under complete exclusion of UV-radiation had no vitamin D-activity at all, but an extract of T. flavescens grown without UV-light showed full vitamin D-activity after short exposure to UV-irradiation. These results indicate that the «animal vitamin D» cholecalciferol not only occurs in a higher plant, but is also formed as in the skin of vertebrate animals by UV-radiation from its precursors.

Course of cellulose decomposition in a brown earth under a Trisetum flavescens – meadow after different fertilization The cellulose decomposition in the soil of a Trisetum flavescens-meadow untreated and treated with NPK. and PK fertilizer was determined by means of burial of pieces of cellophane. The rate of decomposition of the cellulose film was chosen as a measure of cellulolytic activity in soil. The cellulolytic activity had its maximum in the summer months and near the surface. The decrease with increasing depth was more obvious in the untreated lot than in the lot treated with NPK fertilizer. Under field conditions the influence of fertilization on the cellulolytic activity was low. In the laboratory there was a slight effect of the addition of soil from the NPK-lot on the decomposition of filter paper only with a slightly alkaline nutritive solution. The determination of soil cellulose content and mineralization of soil cellulose showed no differences between fertilized and untreated soil.

I. ABSTRACT Calcinosis in grazing animals has been described in various parts of the world and the cause has been attributed to the ingestion of certain plant species. In Argentina and Brazil, the plant involved is Solanum malacoxylon; in Miami, Florida , Cestrum diurnum; and in Austria and Germany , Trisetum flavescens. Glycosides of the active metabolite of vitamin D3, i.e., 1, 25-dihydroxycholecalciferol, have been identified in S. malacoxylon and C. diurnum, and are undoubtedly the calcinogenic principles in these plants. The calcinogenic principle in T. flavescens has not been identified.