INFORMATION SYSTEMS JOURNAL, Issue 4 2003
Michael S. H. Heng
Abstract., Communication plays a crucial role in influencing our social life. However, communication has often been distorted by unequal opportunities to initiate and participate in it. Such conditions have been criticized by Habermas who argues for an ideal speech situation, i.e. a situation of democratic communication with equal opportunities for social actors to communicate in an undistorted manner. This ideal situation is partially being realized by the advent of the internet. The paper describes how an internet-based tool for collaborative authoring was conceptualized, developed and then deployed with Habermas's Critical Social Theory as a guiding principle. The internet-based electronic forum, known by its acronym GRASS (Group Report Authoring Support System), is a web tool supporting the production of concise group reports that give their readers an up-to-date and credible overview of the positions of various stakeholders on a particular issue. Together with people and procedures, it is a comprehensive socio-technical information system that can play a role in resolving societal conflicts. A prototype of GRASS has been used by an environmental group as a new way in which to create a more equal exchange and comparison of ideas among various stakeholders in the debate on genetically modified food. With the widespread use of the internet, such a forum has the potential to become an emergent form of communication for widely dispersed social actors to conduct constructive debate and discussion. The barriers to such a mode of communication still remain , in the form of entrenched power structures, and limitations to human rationality and responsibility. However, we believe that the support provided by the comprehensive system of technological functionality as well as procedural checks and balances provided by GRASS may considerably reduce the impact of these obstacles. In this way, the ideal speech situation may be approximated more closely in reality. [source]

Potential for the dispersal of weed seeds on clothing: An example with Gamba Grass in northern Australia

ECOLOGICAL MANAGEMENT & RESTORATION, Issue 1 2009
Article first published online: 21 APR 200
No abstract is available for this article. [source]

The effect of removing seed from florets on germination and field establishment in a Wallaby Grass (Austrodanthonia fulva) accession

ECOLOGICAL MANAGEMENT & RESTORATION, Issue 2 2004
Ian Cole
No abstract is available for this article. [source]

Talkin''Bout My Generation :Memories of 1968 in Recent German Novels

GERMAN LIFE AND LETTERS, Issue 2 2006
Monika Shafi
This article examines the depiction of 1968 in the novel Rot (2001) by Uwe Timm, in the narrative Mein Jahrhundert (1999) by Günter Grass, and in the autobiographical novel Die Brücke vom goldenen Horn (1998) by Emine Sevgi Özdamar, asking to what extent the concept of generation, understood sociologically and symbolically, is useful in analysing West Germany's 1968 generation and its legacy. The three authors display not only contrasting generational, literary and political profiles, they also entertain a different relationship to German mainstream culture. It becomes clear that Özdamar's novel unsettles precisely this dichotomy between the German mainstream and a multicultural niche-discourse in its intense engagement with the 1968 movement in Germany and Europe. Her text therefore invites us to reconsider the value of the generational parameter in assessing the events of 1968. [source]

The Mystery of Feilenhauer Torgelow: Fontane's Elusive Social Democrat

GERMAN LIFE AND LETTERS, Issue 3 2004
Scott Tatchell
As Günter Grass (among others) has highlighted, Theodor Fontane's Der Stechlin is one of the first German novels to feature a social-democratic politician. This article examines the character of Torgelow, who is elected to the Reichstag. Anything we learn about Torgelow is always at one remove, by way of other characters. He never features directly in the narrative, and remains a mysterious figure. After summarising the political backdrop against which the novel is set and providing a brief overview of Fontane's own attitude to the SPD, the article argues that pragmatic concerns and Fontane's burgeoning interest in the party combine to explain Torgelow's inclusion. Subsequently, Torgelow's abstract characterisation is explained as a consequence of Fontane's desire to portray the fear, loathing and ignorance inherent in bourgeois and aristocratic attitudes towards the party. The argument that Torgelow is a mere cipher for the party is rejected. Instead, Torgelow should be seen in the wider context of Fontane's depiction of the SPD as a whole. Overall, the article argues that the character of Torgelow provides a means for Fontane to acknowledge the SPD's rise, to suggest that its predominance will be of finite duration, and to oppose the party's persecution. [source]

Blinded by the Enlightenment: Günter Grass in Calcutta

GERMAN LIFE AND LETTERS, Issue 3 2003
Daniel Reynolds
Günter Grass's 1988 Zunge zeigen has been criticised as an example of Eurocentricism, an especially harsh charge against this author known for his critique of globalisation. The claim that Grass writes about India as a colonising Westerner overlooks the ways in which he undermines the sovereignty of the Western subject through his polyphonic, self-reflexive account. The result is a sincere attempt to destabilise the oppressive subject he has been accused of promoting. This attempt notwithstanding, Grass's critique does falter for two reasons that critics of Zunge zeigen have not addressed. The first concerns his use of Theodor Fontane both as a bridge to the history of colonialism and as a model for engaged literature. Fontane proves tenuous on both counts, and diverts Grass's attention both from India's colonial history and literary present. Second, Grass's prescription for overcoming the misery he documents in India and Bangladesh , the Enlightenment , ultimately reinscribes a discourse of domination that favours Europe. By choosing Kali, the Hindu goddess of destruction, to represent India, Grass reinforces the notion that rationality is a European invention that is alien to the mystical, chaotic East. Ultimately, Grass fails to account for the Enlightenment's own historical complicity in colonialism. [source]

Soil organic carbon contents in long-term experimental grassland plots in the UK (Palace Leas and Park Grass) have not changed consistently in recent decades

GLOBAL CHANGE BIOLOGY, Issue 7 2009
D. W. HOPKINS
Abstract A recent report of widespread declines in soil organic C (SOC) in the UK over the 10,25 years until the early 2000s has focussed attention on the importance of resampling previously characterized sites to assess long-term trends in SOC contents and the importance of soils as a potentially volatile and globally significant reservoir of terrestrial C. We have used two sets of long-term experimental plots which have been under constant and known management for over a century and for which historical data exist that allow comparison over recent decades to determine what, if any, changes in SOC content have occurred. The plots used are the Palace Leas (PL) Meadow Hay Plots in north-east England (UK) established in 1897, and from the Park Grass (PG) Continuous Hay experiment established in 1856 at Rothamsted in south-east England. Collectively, these plots represent the only grassland sites in the UK under long-term management where changes in SOC over several decades can be assessed, and are probably unique in the world. The plots have received different manure and fertilizer treatment and have been under known management for at least 100 years. In 1982, total SOC contents were determined for the 0,27 cm layer of six of the PL plots using measurements of SOC concentrations, bulk density and soil depth. In 2006, the same six PL plots were resampled and SOC contents determined again. Four of the plots showed no net change in SOC content, but two plots showed net loss of SOC of 15% and 17% (amounting to decreases of 18 and 15 t C ha,1) since 1982. However, these differences in total SOC content were in a similar range to the variations in bulk density (6,31%) with changing soil water content. In 1959, the soil masses and SOC concentrations to 23 cm depth were measured on six PG plots with fertilizer and manure treatments corresponding closely with those measured on PL. In 2002, the SOC concentrations on the same plots were measured again. On three of the PG plots, SOC concentrations had declined by 2,10%, but in the other three it had increased by 4,8% between 1959 and 2002. If it is assumed that the soil bulk density had not changed over this period, the losses of SOC from the top soils ranged range from 10 to 3 t C ha,1, while the gains ranged from 4 to 7 t C ha,1. When the differences with time in SOC contents for the six PL and the six PG plots were examined using paired t -tests, that is, regarding the plots as two sets of six replicate permanent grasslands, there were no significant differences between 1982 and 2006 for the PL plots or between 1959 and 2002 for the PG plots. Thus, these independent observations on similar plots at PL and PG indicate there has been no consistent decrease in SOC stocks in surface soils under old, permanent grassland in England in recent decades, even though meteorological records for both sites indicate significant warming of the soil and air between 1980 and 2000. Because the potential influences of changes in management or land use have been definitively excluded, and measured rather than derived bulk densities have been used to convert from SOC concentrations to SOC amounts, our observations question whether for permanent grassland in England, losses in SOC in recent decades reported elsewhere can be attributed to widespread environmental change. [source]

A history of the European Grassland Federation, 1963,2003

GRASS & FORAGE SCIENCE, Issue 1 2004
W. H. Prins
Abstract The history of the European Grassland Federation (EGF) from its founding in 1963 to 2003 is described. The origins and constitution are described together with its membership. How the structure and functions of the EGF have changed in 40 years are outlined and the management and financial arrangements of the EGF explained. The background to Grass and Forage Science becoming the official journal of the EGF in 1996 is described. The developments that have take place in the content and size of the General Meetings and Symposia, and in their publication as Proceedings, are highlighted. The links to other organizations in grassland research and the future direction of the EGF are explored. [source]

Impact of Phosphorus from Dairy Manure and Commercial Fertilizer on Perennial Grass Forage Production

JOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 6 2003
E. A. Mikhailova
Abstract Increased recovery and recycling of manure phosphorus (P) by crops on dairy farms is needed to minimize environmental problems. The main objective of this study was to compare P utilization by orchardgrass (Dactylis glomerata L.) and tall fescue (Festuca arundinaceae Schreb.) from dairy manure or inorganic fertilizer. The study was conducted from 1994 to 2000 at the Cornell University Baker Farm, Willsboro, NY, on a somewhat poorly drained Kingsbury clay (very,fine, illitic, mesic Aeric Epiaqualfs). The design was a split-plot in a randomized complete block with two manure rates (16 800 and 33 600 kg ha,1) and one nitrogen (N) fertilizer rate (84 kg N ha,1 at spring greenup and 56 kg N ha,1 prior to each regrowth harvest) as the main plots and grass species as subplots replicated six times. Fertilizer P [Ca(H2PO4)2] was applied to the fertilizer treatment in 1995 and 1996 at 11 kg P ha,1 year,1. Orchardgrass P removal averaged 21 % higher than tall fescue P removal for the spring harvest, but orchardgrass averaged 24 % lower P removal than tall fescue removal for all regrowth harvests from 1995,99. Phosphorus herbage concentration in the fertilizer treatment was in the range of 1.9,2.7 g P kg,1 compared with 2.2,5.3 g P kg,1 in the manure treatments. Seasonal P removal ranged from as low as 9.2 kg P ha,1 to as high as 48.5 kg P ha,1. Morgan extractable soil P in the top 0,0.20 m remained high through 1999, with 29.1 kg P ha,1 at the highest manure rate in tall fescue compared with 8.4 kg P ha,1 measured in 1993 prior to the experiment. In 2000, soil P at the highest manure rate in tall fescue dropped to 10.1 kg P ha,1, following cessation of manure application in 1998. Intensively managed harvested orchardgrass and tall fescue have the potential to remove large quantities of manure P. [source]

Effect of dietary copper and vitamin E supplementation, and extensive feeding with acorn and grass on longissimus muscle composition and susceptibility to oxidation in Iberian pigs

JOURNAL OF ANIMAL PHYSIOLOGY AND NUTRITION, Issue 9-10 2001
A. I. Rey
The objective of this study was to assess the effect of dietary copper and/or vitamin E supplementation on composition and oxidation of M. longissimus in Iberian pigs and to compare it with meat samples from pigs produced extensively and fed with acorn and grass. Grass had the highest ,-tocopherol content (> 150 mg/kg DM), while acorns had the highest copper concentration (78.1 mg/kg DM). Dietary treatment did not affect copper composition in muscle and no interactions were detected between copper and ,-tocopherol. The ,-tocopherol content in muscle from pigs fed diets supplemented with ,-tocopheryl acetate (100 mg/kg feed) was 1.5 times greater (p < 0.0001) than those from pigs receiving a basel diet. M. longisssimus dorsi from pigs fed extensively had a higher concentration of ,-tocopherol than those fed in confinement with the basel level of ,-tocopheryl acetate, but lower values than pigs fed supplemented levels. Total n -3 fatty acids (p < 0.02) and hematin (p < 0.0001) concentrations were significantly higher in muscle from pigs fed extensively than when fed in confinement. Muscle homogenates from Iberian pigs fed in extensive conditions showed significantly (p < 0.02) higher susceptibility to oxidation than those from pigs fed mixed diets. Dietary ,-tocopheryl acetate supplementation (100 mg/kg feed) significantly (p < 0.05) reduced lipid oxidation of muscle, while dietary copper concentration did not modify susceptibility to lipid oxidation. Das Ziel dieses Studiums war die Wirkung von Kupfer und Vitamin E Ergänzung im Futter auf die Zusammenstellung und Oxydation von M. longissimus in Iberischen Schweinen zu erforschen und es mit Fleisch-Beispielen von freilaufenden Schweinen zu vergleichen, die mit Eicheln und Gras gefüttert wurden. Gras hatte den höchsten ,-Tocopherolgehalt (> 150 mg/kg), während Eicheln die höchste Kupferkonzentration hatten (78.1 mg/kg). Diätgemäße Behandlung von Kupfer beeinflußte keine kupferne Zusammenstellung im Muskel. Es wurden auch keine Wechselwirkungen zwischen Kupfer und ,-Tocopherol entdeckt. Der ,-Tocopherolgehalt im Muskel von Schweinen, gefüttert mit ,-Tocopherolacetat-Ergänzung (100 mg/kg füttern), war bedeutend größer (p < 0.0001) als jener von Schweinen, die eine fundamentale Nahrung bekamen. Der M. longisssimus dorsi von in Freilauf ernährten Schweinen hatte eine höhere ,-Tocopherol-Konzentration, als der von Schweinen, die mit einem fundamentalen Gehalt an ,-Tocopherolacetat gefüttert wurden (p < 0.0001), aber geringer als der von mit ,-Tocopherol-Ergänzung gefütterten Schweine. Der Gehalt von n -3 Fettsäuren (p < 0.02) und Hematin (p < 0.0001) war beträchtlich höher im Muskel von im Freilauf gefütterten Schweinen, als der von mit konzentrierter Nahrung gefütterten Schweinen. Muskel-Homogenate von freilaufenden Iberischen Schweinen zeigten bedeutend (p < 0.02) höhere Anfälligkeit zu Oxydation, als jene von Schweinen, die mit gemischter Nahrungen gefüttert wurden. Diätgemäße ,-Tocopherolazetat-Ergänzung (100 mg/kg füttern) zeigte bedeutend (p < 0.05) reduzierte lipoide Oxydation des Muskels, während diätgemäße kupferne Konzentration die Anfälligkeit zu lipoider Oxydation nicht modifizierte. [source]

Post-dispersal fate of seeds in the Monte desert of Argentina: patterns of germination in successive wet and dry years

JOURNAL OF ECOLOGY, Issue 6 2000
Luis Marone
Summary 1,Patterns of seed germination of grass and forb species were studied in open Prosopis woodland of the central Monte desert (Argentina) during several years, to test the hypotheses that (i) seed germination is positively affected by both rainfall and protection afforded by vegetation cover (a facilitative effect), (ii) the number of surviving plants is positively influenced by rainfall but negatively affected by established vegetation (a competitive effect), and (iii) seed loss from soil banks owing to germination is lower than that caused by granivorous animals. 2,Forb species germinated during restricted periods, either in early autumn or in spring. Grasses, however, germinated throughout the growing season, but because seedlings could not be identified to species level, it was impossible to discern whether different species germinated in particular seasons, or if all grasses germinated in all seasons. Grass and forb germination were generally of similar magnitude, but grass germination increased by an order of magnitude during a summer of unusually abundant rainfall related to an El Niño Southern Oscillation (ENSO) event. 3,Overall, the spatial distribution of neither germinating seeds nor surviving plants could be explained by interactions with established vegetation (facilitation and competition effects, respectively). An alternative explanation may be provided by the distribution of forb and grass seeds in the soil. 4,Seed loss owing to germination was low in both dry and rainy years. For forbs, such loss totalled <,1% of soil-seed reserves, and no forb species suffered losses >,4%. Total grass-seed loss to germination was usually <,0.5%, and the 5% reached in 1997,98 corresponded to an interruption of a prolonged drought by unusually abundant rainfall associated with a reduced seed bank. 5,Grass-seed loss caused by germination was one to two orders of magnitude lower than that reported due to autumn-winter granivory in the central Monte desert. [source]

Intensity and Importance of Competition for a Grass (Festuca rubra) and a Legume (Trifolium pratense) Vary with Environmental Changes

JOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 12 2008
Junyan Zhang
Abstract How plant competition varies across environmental gradients has been a long debate among ecologists. We conducted a growth chamber experiment to determine the intensity and importance of competition for plants grown in changed environmental conditions. Festuca rubra and Trifolium pratense were grown in monoculture and in two- and/or three-species mixtures under three environmental treatments. The measured competitive variations in terms of growth (height and biomass) were species-dependent. Competition intensity for Festuca increased with decreased productivity, whilst competition importance displayed a humpback response. However, significant response was detected in neither competition intensity nor importance for Trifolium. Intensity and importance of competition followed different response patterns, suggesting that they may not be correlated along an environmental gradient. The biological and physiological variables of plants play an important role to determine the interspecific competition associated with competition intensity and importance. However, the competitive feature can be modified by multiple environmental changes which may increase or hinder how competitive a plant is. [source]

Incomplete Information and Migration: the Grass is Greener Across the Higher Fence,

JOURNAL OF REGIONAL SCIENCE, Issue 1 2005
Jeremiah M. Allen
Diverse empirical results support this belief. Here we show that if agents are risk-neutral, less information about a location not only is not a barrier to migration to that location, it is actually an attractor. Only if agents are Bayesian and risk-averse is less information a barrier. [source]

Runoff transport of faecal coliforms and phosphorus released from manure in grass buffer conditions

LETTERS IN APPLIED MICROBIOLOGY, Issue 3 2005
W.L. Stout
Abstract Aims:, To test the hypothesis that faecal coliform (FC) and phosphorus (P) are transported similarly in surface runoff through the vegetative filter strip after being released from land-applied manure. Methods and Results:, The Hagerstown soil was packed into boxes that were 10 cm deep, 30 cm wide and 100, 200 or 300 cm long. Grass was grown in boxes prior experiments. Same-length boxes were placed under rainfall simulator and tilted to have with either 2% or 4% slopes. Dairy manure was broadcast on the upper 30-cm section. Rainfall was simulated and runoff samples were collected and analysed for Cl, FC and total phosphorus (TP). Mass recovery, the concentration decrease rate k, and the ratio FC : TP showed that there was a consistent relationship between FC and TP in runoff. Conclusion:, The FC and TP transport through simulated vegetated buffer strips were highly correlated. Significance and Impact of the Study:, As a knowledge base on the effect of the environmental parameters on P transport in vegetated buffer strips is substantially larger than for manure-borne bacteria, the observed similarity may enhance ability to assess the efficiency of the vegetated buffer strips in retention of FC currently used as indicator organisms for manure-borne pathogens. [source]

Günter Grass: Hundejahre oder La diabolica commedia germanica

ORBIS LITERARUM, Issue 6 2006
Dieter Arendt
Hundejahre, der Titel ist beredt: Jahre der Not und des Elends, etwa Kriegsjahre oder Nachkriegsjahre. Hunde spielen ihren Part, nicht zuletzt ein Hund, ein schwarzer deutscher Schäferhund. Assoziationen sind vielfältig: Rannte nicht ein schwarzer Hund durch Saat und Koppeln und entpuppte sich als diabolischer Scholastikus? Hält nicht ein schwarzer Hund Wache vor den Toren des Orkus? Und hatte nicht ein oberster Kriegsherr einen schwarzen Schäferhund? Die Hysteron-Proteron-Erzählweise ist ein adäquater Kunstgriff für die schleichende Dämonisierung des kleinbürgerlichen Alltags an der Weichsel. Die Rollen-Erzähler waren dort Kinder und kennen sich bestens aus hinter den Deichen und als Gymnasiasten in der nahen Stadt , und hinter ihnen steht ein orts- und zeitkundiger Autor. An den Fäden des halbjüdischen Redakteurs und Regisseurs Brauxel oder Brauchsel , wie Weichsel , hängen und agieren die tagblinden Primaner-Soldaten und die bramarbasierenden Partei-Bonzen. Sie erinnern sich genau, aber ihr Gedächtnis ist ein blinder Spiegel. Brauxel fabriziert in seinem Bergwerk , wie als Junge schon an der Weichsel , Scheuchen als gespenstische Karikaturen der historischen und zeitgenössischen Heroen. Erst als er im Bergwerk seinen Scheuchen-Reigen vor Augen führt, dämmert im Zwielicht der Karbidlampe die deutsche Historie als Karneval der Welt- Geschichte. Dem Titel Hundejahre korrespondiert in spiegelbildlicher Analyse der wortkarge Epilog: ,,Der Orkus ist oben.,, [source]

Standard assays do not predict the efficiency of commercial cellulase preparations towards plant materials

BIOTECHNOLOGY & BIOENGINEERING, Issue 1 2006
Mirjam A. Kabel
Abstract Commercial cellulase preparations are potentially effective for processing biomass feedstocks in order to obtain bioethanol. In plant cell walls, cellulose fibrils occur in close association with xylans (monocotyls) or xyloglucans (dicotyls). The enzymatic conversion of cellulose/xylans is a complex process involving the concerted action of exo/endocellulases and cellobiases yielding glucose and xylanases yielding xylooligomers and xylose. An overview of commonly measured cellulase-, cellobiase-, and xylanase-activity, using respectively filter paper, cellobiose, and AZCL-dyed xylan as a substrate of 14 commercially available enzyme preparations from several suppliers is presented. In addition to these standardized tests, the enzyme-efficiency of degrading native substrates was studied. Grass and wheat bran were fractionated into a water unsoluble fraction (WUS), which was free of oligosaccharides and starch. Additionally, cellulose- and xylan-rich fractions were prepared by alkaline extraction of the WUS and were enzymatically digested. Hereby, the capability of cellulose and xylan conversion of the commercial enzyme preparations tested was measured. The results obtained showed that there was a large difference in the performance of the fourteen enzyme samples. Comparing all results, it was concluded that the choice of an enzyme preparation is more dependent on the characteristics of the substrate rather than on standard enzyme-activities measured. © 2005 Wiley Periodicals, Inc. [source]

Blinded by the Enlightenment: Günter Grass in Calcutta

Effects of environmental perturbations on abundance of subarctic plants after three, seven and ten years of treatments

ECOGRAPHY, Issue 1 2001
Enrico Graglia
Analyses of changes in vegetation were carried out after three, seven and ten years of fertilizer addition, warming and light attenuation in two subarctic, alpine dwarf shrub heaths. One site was just above the tree line, at ca 450 m a.s.l., and the other at a much colder fell-field at ca 1150 m altitude. The aim was to investigate how the treatments affected the abundance of different species and growth forms over time, including examinations of transient changes. Grasses, which increased in abundance by fertilizer addition, and cryptogams, which, by contrast, decreased by fertilizer addition and warming, were the most sensitive functional groups to the treatments at both sites. Nutrient addition exerted a stronger and more consistent effect than both shading and warming. Warming at the fell-field had slightly greater effect than at the warmer tree line with an increase in deciduous shrubs. The decreased abundance of mosses and lichens to fertilizer addition and/or warming was most likely an indirect treatment effect, caused by competition through increased abundance and overgrowth of grasses. Such changes in species composition are likely to alter decomposition rates and the water and energy exchange at the soil surface. We observed few, if any, transient effects of declining responses during the 10 yr of treatments. Instead, there were many cumulative effects of the treatments for all functional groups and many interactions between time and treatment, suggesting that once a change in community composition is triggered, it will continue with unchanged or accelerated rate for a long period of time. [source]

Below-ground competition between trees and grasses may overwhelm the facilitative effects of hydraulic lift

ECOLOGY LETTERS, Issue 8 2004
F. Ludwig
Abstract Under large East African Acacia trees, which were known to show hydraulic lift, we experimentally tested whether tree roots facilitate grass production or compete with grasses for below-ground resources. Prevention of tree,grass interactions through root trenching led to increased soil water content indicating that trees took up more water from the topsoil than they exuded via hydraulic lift. Biomass was higher in trenched plots compared to controls probably because of reduced competition for water. Stable isotope analyses of plant and source water showed that grasses which competed with trees used a greater proportion of deep water compared with grasses in trenched plots. Grasses therefore used hydraulically lifted water provided by trees, or took up deep soil water directly by growing deeper roots when competition with trees occurred. We conclude that any facilitative effect of hydraulic lift for neighbouring species may easily be overwhelmed by water competition in (semi-) arid regions. [source]

Species-level effects more important than functional group-level responses to elevated CO2: evidence from simulated turves

FUNCTIONAL ECOLOGY, Issue 3 2004
M. E. HANLEY
Summary 1Using mixtures of 14 calcareous grassland plant species drawn from three functional groups, we looked at the effects of elevated atmospheric CO2 on contrasting levels of ecosystem performance (species, functional group and community). Experimental communities were subjected to ambient (,350 µmol mol,1) or elevated CO2 (,600 µmol mol,1) in controlled environments, with grazing simulated by clipping at monthly intervals for 546 days. 2We assessed the effect of elevated CO2 on plant performance by quantifying the productivity (biomass) and cover of component species. We also examined the effect of elevated CO2 on the vertical structure of the plant canopy. Elevated CO2 resulted in a significant increase in total community biomass only following nutrient addition. Within functional groups, non-leguminous forb species had significantly greater biomass and cover in elevated CO2 both before and after nutrient addition, although the effect was mainly due to the influence of one species (Centaurea nigra). Grasses, in contrast, responded negatively to elevated CO2, although again significant reductions in biomass and cover could mainly be ascribed to a single species (Brachypodium pinnatum). Legumes exhibited increased biomass and cover in elevated CO2 (the effects being particularly marked for Anthyllis vulneraria and Lotus corniculatus), but this response disappeared following nutrient addition. Vertical structure was little affected by CO2 treatment. 3We conclude that due to the idiosyncratic responses of individual species, the categorization of plants into broad functional groups is of limited use in guiding our understanding of the impacts of elevated atmospheric CO2 on plant communities. [source]

Loss of forb diversity in relation to nitrogen deposition in the UK: regional trends and potential controls

GLOBAL CHANGE BIOLOGY, Issue 10 2006
CARLY J. STEVENS
Abstract In this study we investigate the impact of nitrogen (N) deposition on the diversity of three different vegetation functional groups , forbs, grasses and mosses , using a field survey of acid grasslands across Great Britain. Our aim is to identify the vegetation types that are most vulnerable to enhanced N deposition, and to shed light on the mechanisms that may be driving N-initiated species changes in the UK. Sixty-eight randomly selected grasslands belonging to the UK National Vegetation Classification group U4 (Festuca ovina,Agrostis capillaris,Galium saxatile grassland) were studied along a gradient of atmospheric N deposition ranging from 6 to 36 kg N ha,1 yr,1. At each site, vegetation was surveyed and samples were taken from the topsoil and subsoil. Aboveground plant material was collected from three species: a forb, grass and moss. Both the species richness and cover of forbs declined strongly with increasing N deposition, from greater than eight species/20% cover per m2 quadrat at low levels of N to fewer than two species/5% cover at the highest N deposition levels. Grasses showed a weak but significant decline in species richness, and a trend toward increasing cover with increasing N input. Mosses showed no trends in either species richness or cover. Most of the decline in plant species richness could be accounted for by the level of ammonium deposition. Soil KCl-extractable ammonium concentration showed a significant positive correlation with N input, but there was no relationship between N deposition and extractable nitrate. In the soil O/A horizon, there was no relationship between N deposition and %N, and only a very weak positive relationship between the level of N deposition and the C : N ratio. Finally, in the vegetation, there was no relationship between N deposition and either shoot tissue N concentration or N : P ratio for any of the three reference species. Combining our regional survey with the results of published N-addition experiments provides compelling evidence that there has been a significant decline in the species richness and cover of forbs across Great Britain, and that the primary cause is competition due to an increase in the cover of grasses in response to enhanced deposition of reactive N, primarily NH4+. [source]

C3 grasses have higher nutritional quality than C4 grasses under ambient and elevated atmospheric CO2

GLOBAL CHANGE BIOLOGY, Issue 9 2004
Raymond V. Barbehenn
Abstract Grasses with the C3 photosynthetic pathway are commonly considered to be more nutritious host plants than C4 grasses, but the nutritional quality of C3 grasses is also more greatly impacted by elevated atmospheric CO2 than is that of C4 grasses; C3 grasses produce greater amounts of nonstructural carbohydrates and have greater declines in their nitrogen content than do C4 grasses under elevated CO2. Will C3 grasses remain nutritionally superior to C4 grasses under elevated CO2 levels? We addressed this question by determining whether levels of protein in C3 grasses decline to similar levels as in C4 grasses, and whether total carbohydrate : protein ratios become similar in C3 and C4 grasses under elevated CO2. In addition, we tested the hypothesis that, among the nonstructural carbohydrates in C3 grasses, levels of fructan respond most strongly to elevated CO2. Five C3 and five C4 grass species were grown from seed in outdoor open-top chambers at ambient (370 ppm) or elevated (740 ppm) CO2 for 2 months. As expected, a significant increase in sugars, starch and fructan in the C3 grasses under elevated CO2 was associated with a significant reduction in their protein levels, while protein levels in most C4 grasses were little affected by elevated CO2. However, this differential response of the two types of grasses was insufficient to reduce protein in C3 grasses to the levels in C4 grasses. Although levels of fructan in the C3 grasses tripled under elevated CO2, the amounts produced remained relatively low, both in absolute terms and as a fraction of the total nonstructural carbohydrates in the C3 grasses. We conclude that C3 grasses will generally remain more nutritious than C4 grasses at elevated CO2 concentrations, having higher levels of protein, nonstructural carbohydrates, and water, but lower levels of fiber and toughness, and lower total carbohydrate : protein ratios than C4 grasses. [source]

Grasses and grassland ecology

GRASS & FORAGE SCIENCE, Issue 3 2009
Alan Hopkins
No abstract is available for this article. [source]

Climate change and grasslands through the ages: an overview

GRASS & FORAGE SCIENCE, Issue 2 2007
L. 't Mannetje
Summary Change from cool to warm temperatures and vice versa have occurred throughout geological time. During the Jurassic and Cretaceous periods (206,65 million years ago, Ma) the climate was more uniformly warm and moist than at present and tropical rainforests were widespread. Grasses evolved during the Jurassic period and they expanded greatly as the climate differentiated with reduced rainfall and temperatures. C4 -grasses probably arose during the Oligocene period (24,35 Ma). During the Miocene period (23·8,5·3 Ma) grasslands expanded into huge areas (e.g. prairies in the USA, steppe in Eurasia, and pampas and llanos in South America). During the Quaternary period (1·8 Ma till now) some twenty-two different ice ages with periodicities of about 100 000 years occurred. Eighteen-thousand years ago, north-western Europe had a polar climate with tundra vegetation and the Mediterranean region was covered by steppe. During that time Amazonia was so dry that it was covered in extensive areas of savanna and the Sahara expanded rapidly. Only in the last 10 000 years has a closed rainforest covered the Amazonian region again. However, 9000 years ago a brief period of global warming caused excessive rains, which caused the sea and river levels to rise in north-western Europe with tremendous loss of life. The present period of extreme dryness in the Sahara only started some 5000 years ago and then the desert expanded rapidly into the Sahel. Before that the Sahara was covered by steppe. Global warming took place between about ad 900 and about ad 1200 or 1300 just before the Little Ice Age (1550,1700 ad). The article concludes with a description of temperature and vegetation changes that are occurring in Europe at present. It is predicted that C4 -grasses, which are already present in southern Europe, will further expand but that, in the short term, land abandonment will have much more deleterious effects than temperature change due to increased wild fires, loss of biodiversity and desertification. [source]

Cadmium phytoextraction capacity in eight C3 herbage grass species

GRASSLAND SCIENCE, Issue 1 2008
Shamima Sabreen
Abstract Grasses are excellent candidates for phytoremediation because of their high biomass production, high adaptability and low management cost. This study assesses interspecific variation of cadmium (Cd) phytoextraction capabilities in eight C3 grass species. Populations of 30-day-old C3 grass species , namely, Agrostis alba, Anthoxanthum odoratum, Dactylis glomerata, Festuca arundinacea, Festuca pratensis, Lolium multiflorum, Lolium perenne and Poa pratensis, were grown hydroponically for 15 days with different concentrations of Cd (0, 5, 10 and 50 µM). For each species, shoot biomass, the proportion of growth inhibition (GI, %), shoot Cd concentration and accumulation, shoot nutrient uptake, and the proportion of uptake inhibition (UI, %) of nutrient minerals were evaluated. Effects of Cd application included stunted growth. The GI increased from 5% to 70% with an increase in Cd concentrations. For all Cd treatments, L. multiflorum showed the highest shoot dry biomass. Shoot Cd concentrations negatively affected mineral nutrient uptake. The highest Cd treatment caused UI of various elements of 37,95%. Under 50-µM Cd treatment, Cd accumulation varied by 20 times among species, and L. multiflorum showed the highest Cd accumulation (116.46 µg plant,1). Our results indicate that L. multiflorum exhibited high degrees of both Cd tolerance and Cd phytoextraction capacity among grass species. [source]

The irreversible cattle-driven transformation of a seasonally flooded Australian savanna

JOURNAL OF BIOGEOGRAPHY, Issue 5 2003
Ben R. Sharp
Abstract Aim ,Anecdotal historical and photographic evidence suggests that woody vegetation is increasing dramatically in some northern Australian savanna habitats. Vegetation change in savannas has important implications for pastoral land-use, conservation management, and landscape-scale carbon storage, and informs theoretical debates about ecosystem function. This study seeks to determine the nature, extent and cause(s) of woody vegetation change in a seasonally flooded alluvial savanna habitat. Location ,The study area is located within the seasonally inundated alluvial zone of the tidal portion of the Victoria River, Northern Territory, Australia. The study area has been grazed by domestic stock since c. 1900, prior to which the area was inhabited and more likely regularly burnt by Aboriginal people for thousands of years. Methods ,Digital georeferenced aerial photographic coverages were used to examine and quantify woody vegetation change between 1948 and 1993. Transect surveys of woody and herbaceous vegetation were carried out to ground-truth air-photo results and determine the nature and causes of observed vegetation changes. Results ,There has been a dramatic increase in woody vegetation cover throughout the study area. Vegetation change patterns are roughly uniform across the full range of edaphic habitat variation and are unrelated to the depositional age of fluvial sediments. Two woody species, Eucalyptus microtheca and Excoecaria parvifolia, are predominantly responsible for observed increases. Demographic analyses reveal that woody invasions have been episodic and indicate that in most locations peak woody species establishment occurred in the mid-1970s. Grasses are almost absent in a majority of habitats within the study area. Instead, large areas are covered by scalded soil, dense invasive weed populations, and unpalatable forbs and sedges. What grasses do occur are predominantly of very low value for grazing. The condition of the herbaceous layer renders most of the study area almost completely non-flammable; what fires do burn are small and of low intensity. Main conclusions ,Multiple working hypotheses explaining observed patterns of woody vegetation increase were considered and rejected in turn. The only hypothesis consistent with the evidence is as follows: (1) observed changes are a direct consequence of extreme overgrazing by cattle, most likely when stocking rates peaked in the mid-1970s; (2) prolonged heavy grazing effected the complete transformation of much of the herbaceous vegetation to a new state that is not flammable; and (3) in the absence of regular fire mortality, woody vegetation increased rapidly. The relatively treeless system that existed in 1948 was apparently stable and resilient to moderate grazing levels, and perhaps also to episodic heavy grazing events. However, grazing intensity in excess of a sustainable threshold has forced a transition that is irreversible in the foreseeable future. Stable-state transitions such as this one inform debates at the heart of ecological theory, such as the nature of stability, resilience, equilibrium and carrying capacity in dynamic savanna ecosystems. [source]

Post-dispersal fate of seeds in the Monte desert of Argentina: patterns of germination in successive wet and dry years

Kinematic Analysis of Leaf Growth in Grasses: A Comment on Spatial and Temporal Quantitative Analysis of Cell Division and Elongation Rate in Growing Wheat Leaves under Saline Conditions

JOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 5 2009
Hans Schnyder
[source]

Symbiont-mediated changes in Lolium arundinaceum inducible defenses: evidence from changes in gene expression and leaf composition

NEW PHYTOLOGIST, Issue 3 2007
Terrence J. Sullivan
Summary ,,Plants have multiple strategies to deal with herbivory, ranging from chemical or physical defenses to tolerating damage and allocating resources for regrowth. Grasses usually tolerate herbivory, but for some cool-season grasses, their strategy may depend upon their interactions with intracellular symbionts. Neotyphodium endophytes are common symbionts in pooid grasses, and, for some host species, they provide chemical defenses against both vertebrate and invertebrate herbivores. ,,Here, it was tested whether defenses provided by Neotyphodium coenophialum in Lolium arundinaceum (tall fescue) are inducible by both mechanical damage and herbivory from an invertebrate herbivore, Spodoptera frugiperda (fall armyworm), via a bioassay and by quantifying mRNA expression for lolC, a gene required for loline biosysnthesis. ,,Both mechanical and herbivore damage had a negative effect on the reproduction of a subsequent herbivore, Rhopalosiphum padi (bird cherry-oat aphid), and herbivore damage caused an up-regulation of lolC. Uninfected grass hosts also had significantly higher foliar N% and lower C : N ratio compared with infected hosts, suggesting greater allocation to growth rather than defense. ,,For L. arundinaceum, N. coenophialum appears to switch its host's defensive strategy from tolerance via compensation to resistance. [source]

Grass blades as tree rings: environmentally induced changes in the oxygen isotope ratio of cellulose along the length of grass blades

NEW PHYTOLOGIST, Issue 3 2002
Brent R. Helliker
Summary ,,In this study, we tested the hypothesis that environmentally induced changes in the oxygen isotope ratio of leaf water are recorded in grass blade cellulose during leaf-blade expansion. ,,Grasses were grown hydroponically in chambers that allowed for control of relative humidity while keeping isotopic inputs (namely source water) constant. ,,In experiments where relative humidity was changed from 35% to 93% during grass blade expansion, a 10, shift in cellulose , 18 O was observed along single grass blades of Lolium multiflorum . However, statistically significant changes were not detectable with relative humidity of 93% to 70%. ,,It is shown that grass blades, analogously to tree rings, record environmental change on an interseasonal basis. In light of this, care must be taken to compare leaves of the same developmental stage to avoid confusion of environmental effects with physiological effects in interpretations of leaf organic material , 18 O. The results presented here confirm the ability of the current empirical models to predict the oxygen isotope ratio of cellulose in both grass blades that expanded in constant and variable growth conditions. [source]