Nardus Research Articles

Reduced nitrogen has a greater effect than oxidised nitrogen on dry heathland vegetation

We investigated the effects of different ratios of reduced (NH 4 +) versus oxidised (NO 3 −) nitrogen in deposition on heathland and species-rich grassland vegetation at high nitrogen deposition levels in large mesocosms filled with nutrient-poor soils to which different NH 4 +/NO 3 − ratios were applied. The response of the forbs, Antennaria dioica, Arnica montana, Gentiana pneumonanthe, Thymus serpyllum, the grasses Danthonia decumbens, Deschampsia flexuosa, Nardus stricta and the shrub Calluna vulgaris was recorded. The forb A. dioica and the grass D.decumbens preferred low NH 4 +/NO 3 − ratios and were characterised by a negative correlation between NH 4 +/NO 3 − ratios and biomass and survival, whereas the grasses N. stricta and D. flexuosa showed no correlation with NH 4 +/NO 3 − ratios. Lime addition eliminated the negative effects of high NH 4 + concentrations in deposition for A. dioica and the grass D. decumbens. The implications of these findings for heathland vegetations are discussed.

Évolution de pâturages abandonnés dans des landes du massif du mont Grappa (Vénétie, nord—est de l'Italie)

To have more insight into the vegetation dynamics of the mountain pastures after their abandon, two areas in the Massiccio del Grappa where abandoned and still grazed pastures have been studied. The results show that such type of pasture, when abandoned, can evolve in two different ways. If the soil is shallow, after at least 15 years, a « sward with Nardus stricta » with abundant presence of Calluna vulgaris was established. After a further 15-years period some trees appeared. Where the soil was deeper, at the beginning of the succession, Veratrum album invaded the pastures reducing the number of species of about one third. Then Vaccinium myrtillus become also very abundant. The two above species delayed the reconstruction of the climax forest.

Complementarity in mineral nitrogen use among dominant plant species in a subalpine community

The underlying mechanisms that enable plant species to coexist are poorly understood. Complementarity in resource use is among the major mechanisms proposed that could favor species coexistence but is insufficiently documented. In alpine soil, low temperatures are a major constraint for the supply of plant nitrogen. We carried out (15)N labeling of soil mineral N to determine to what extent four major species of a subalpine community compete for N, or develop ionic (NH(4)(+) vs. NO(3)(-)) or temporal complementarity. The Poaceae took up much more (15)N per soil area unit than the ericaceous species, and all species displayed three major strategies in exploiting (15)N: (1) uptake mainly early in the growing season (Vaccinium myrtillus), (2) uptake at a slow and similar rate throughout the growing season (Rhododendron ferrugineum), and (3) uptake at high rates over the growing season (Festuca eskia and Nardus stricta). However, while F. eskia used (15)NH(4)(+) mainly early and (15)NO(3)(-) mainly late in the growing season, the reverse was observed for N. stricta. Taking into account (15)N dilution in soil NH(4)(+) and NO(3)(-) pools, we calculated that NH(4)(+) provided more than 80% of the mineral N uptake in Ericaceae and about 60% in grasses. Together, such ionic and temporal complementarity would reduce competition between species and could be a major mechanism promoting species diversity.

The Grass Garden in the Giant Mts. (Czech Republic): Residual effect of long-term fertilization after 62 years

The aim of the study was to investigate how plant species’ composition, soil parameters and nutrient concentrations in plant biomass differ between fertilized and control plots 62 years after the last fertilizer application on a sub-alpine grassland. A piece of land called the Grass Garden (GG), fertilized with wood ash and manure for at least 200 years, was rediscovered in the Giant Mts. (Krkonoše, Karkonosze) in 2006. The last fertilization was applied in 1944. The central part of GG (treatment A), the edge of GG (treatment B) and never-fertilized control plots outside of GG (treatment C) were distinguished. Sixty-two years after the last fertilization Nardus stricta was dominant in treatment C and Deschampsia cespitosa and Avenella flexuosa in treatments A and B. The predominance of these grasses was first described in 1786 and repeatedly during the 19th and 20th centuries and indicated the long-term stability of plant species’ composition in the sub-alpine grassland. In the case of GG, long-term fertilization has had a long-term “stable after-effect” upon differences in plant species’ composition. Ca concentration in the soil was more than two times higher in treatments A and B than in the control, indicating that it was very difficult to deplete applied Ca even on extreme podzol soils and under the climatic conditions of the sub-alpine vegetation belt. In above-ground plant biomass, Mg and P concentrations and N:P ratio were still significantly affected by treatment.

Temperature dependences of carbon assimilation processes in four dominant species from mountain grassland ecosystem

Temperature responses of carbon assimilation processes were studied in four dominant species from mountain grassland ecosystem, i.e. Holcus mollis (L.), Hypericum maculatum (Cr.), Festuca rubra (L.), and Nardus stricta (L.), using the gas exchange technique. Leaf temperature (T L) of all species was adjusted within the range 13–30 °C using the Peltier thermoelectric cooler. The temperature responses of metabolic processes were subsequently modelled using the Arrhenius exponential function involving the temperature coefficient Q 10. The expected increase of global temperature led to a significant increase of dark respiration rate (R D; Q 10 = 2.0±0.5), maximum carboxylation rate (V Cmax; Q 10 = 2.2±0.6), and maximum electron transport rate (J max; Q 10 = 1.6±0.4) in dominant species of mountain grassland ecosystems. Contrariwise, the ratio between J max and V Cmax linearly decreased with T L [y = −0.884 T L + 5.24; r 2 = 0.78]. Hence temperature did not control the ratio between intercellular and ambient CO2 concentration, apparent quantum efficiency, and photon-saturated CO2 assimilation rate (P max). P max primarily correlated with maximum stomatal conductance irrespective of T L. Water use efficiency tended to decrease with T L [y = −0.21 T L + 8.1; r 2 = 0.87].

Do plant species with different growth strategies vary in their ability to compete with soil microbes for chemical forms of nitrogen?

We used dual labelled stable isotope ( 13C and 15N) techniques to examine how grassland plant species with different growth strategies vary in their ability to compete with soil microbes for different chemical forms of nitrogen (N), both inorganic and organic. We also tested whether some plant species might avoid competition by preferentially using different chemical forms of N than microbes. This was tested in a pot experiment where monocultures of five co-existing grassland species, namely the grasses Agrostis capillaris, Anthoxanthum odoratum, Nardus stricta, Deschampsia flexuosa and the herb Rumex acetosella, were grown in field soil from an acid semi-natural temperate grassland. Our data show that grassland plant species with different growth strategies are able to compete effectively with soil microbes for most N forms presented to them, including inorganic N and amino acids of varying complexity. Contrary to what has been found in strongly N limited ecosystems, we did not detect any differential uptake of N on the basis of chemical form, other than that shoot tissue of fast-growing plant species was more enriched in 15N from ammonium-nitrate and glycine, than from more complex amino acids. Shoot tissue of slow-growing species was equally enriched in 15N from all these N forms. However, all species tested, least preferred the most complex amino acid phenylalanine, which was preferentially used by soil microbes. We also found that while fast-growing plants took up more of the added N forms than slow-growing species, this variation was not related to differences in the ability of plants to compete with microbes for N forms, as hypothesised. On the contrary, we detected no difference in microbial biomass or microbial uptake of 15N between fast and slow-growing plant species, suggesting that plant traits that regulate nutrient capture, as opposed to plant species-specific interactions with soil microbes, are the main factor controlling variation in uptake of N by grassland plant species. Overall, our data provide insights into the interactions between plants and soil microbes that influence plant nitrogen use in grassland ecosystems.

Interactions between sheep, rodents, graminoids, and bryophytes in an oceanic alpine ecosystem of low productivity

Large herbivores directly affect plant communities in alpine ecosystems. In addition, they may compete with, or facilitate foraging by, small herbivores and also cause strong indirect effects on plants. We used an exclosure experiment to examine short-term (5-y) effects of cessation of sheep grazing on rodent grazing and plant communities in an oceanic alpine environment of low productivity with a long history of heavy sheep grazing. Exclusion of sheep significantly impacted plant communities. Vascular plant height increased, but Deschampsia flexuosa was the only vascular plant species that increased in sheep exclosures. Changes in the frequency of graminoids, herbs, and dwarf shrubs in exclosed plots were not related to cessation of grazing, but 6 bryophyte species significantly increased or decreased in response to exclusion of sheep. The absence of large grazers thus brought about a change in the species composition in favour of successional bryophytes and the preferred fodder plant. Neither vascular plant nor bryophyte species richness, nor the total cover of bryophytes and lichens, were affected. Cessation of sheep grazing reduced the level of rodent grazing. Rodent grazing correlated with changes in plant communities that led to reduced height and cover of vascular plants, reduced cryptogam cover, and reduced frequencies of 3 bryophyte species. A strong correlation between sheep fodder value index and rodent grazing indirectly indicated additive herbivory. In addition, some of the rodent effects were compensatory; e.g., Nardus stricta, which is not grazed by sheep, was significantly reduced by rodents. Our study points to a more central role of facilitation in structuring herbivore assemblages in the short term, with direct implications for the joint effects of large and small herbivores on the cover and frequency of graminoids and bryophytes.

Footpath morphology and terrain sensitivity on high plateaux: the Mamore Mountains, Western Highlands of Scotland

AbstractVariations in the morphology of a high‐level footpath are characterized using a new approach that relates footpath morphology to six terrain units defined jointly by two contrasting plant communities (U7 grass–heath communities dominated by Nardus stricta and Carex bigelowii, and U10 moss–heath communities dominated by Carex bigelowii and Racomitrium lanuginosum) and by the contrasting textural characteristics of underlying mineral soils developed on schist, granite and quartzite. All six terrain units are characterized by distinct footpath morphologies. The most critical factor affecting footpath morphology is the shear strength of the vegetation mat and underlying root zone. Vegetation mat shear strength was measured using a specially constructed shear rake. On all three lithologies, median shear strengths for U7 communities significantly exceed those for U10 communities, so that pathways on the former are significantly narrower and deeper than those developed on the latter. Adjacent zones of damaged or modified vegetation cover are also wider on U10 communities. The role of mineral soil (regolith) texture and thus underlying lithology in controlling footpath morphology is more complex. For soils with abundant fines, granite soils have lower shearing resistance than schist soils, and are associated with wider footpaths. Footpaths are also wide on clast‐supported quartzite regolith, which has high shearing resistance: pathways are trapezoidal in cross‐section in areas of U7 vegetation cover, but footpaths are very broad and diffuse in areas of U10 cover. Pathway depths are limited by increasing shear and compressive strength with depth. Implications of these findings for further research and management strategies are discussed. Copyright © 2007 John Wiley & Sons, Ltd.

Fine‐scale dynamics of rhizomes in a grassland community

Spatial dynamics in grassland communities are constrained by the belowground spatial distribution of roots and rhizomes. Their dynamics are difficult to measure as underground data collection tends to be destructive and cannot be repeated at the same plot over time. We investigated rhizome dynamics indirectly by examining rhizome spatial structure on long‐term grassland study plots where aboveground shoot counts have been recorded using a fine‐scale grid over nine years. Number of rhizome apical ends, basal ends and total rhizome length of both live and dead rhizomes were obtained from the data by scanning rhizomes and processing them by GIS vectorization. These rhizome variables were correlated with the above‐ground shoot counts in grid cells over varying temporal lags. There was a general decrease in the intensity of correlation between live rhizomes and shoot counts with increasing time lags. Correlation of dead rhizomes increased with increasing time lag, reaching a maximum after several years, and then declined. Species differed strongly in the change of rhizome‐shoot counts correlation over varying time lags. These differences were used to infer rhizome growth dynamics, namely rhizome growth rate and lifespan, and rhizome mean decomposition time. The species involved differed in all these traits. Mean rhizome growth rate ranged from 0.2 (Polygonum bistorta) to 3.3 cm ur−1 (Deschampsia flexuosa); mean rhizome lifespan ranged from 5 yr (Anthoxanthum alpinum) to over 8 yr (Nardus stricta) and mean decomposition time from one growing season (Anthoxanthum) to 7 yr (Polygonum). Presence of dead rhizomes below living rhizomes or aboveground shoots was taken as an indication of fine‐scale replacements between species. These were highly non‐random, with some species pairs replacing significantly more frequently. These differences in rhizome growth parameters underlie different strategies of horizontal growth and dieback between species. These can serve as one of the mechanisms of species replacements and contribute to the fine‐scale coexistence of species.

Chemical composition and net energy content of alpine pasture species during the grazing season

The aim of this study was to investigate changes over time in chemical composition, digestibility and net energy for lactation (NEl) contents of 12 species of alpine pastures during the vegetative season ( i.e., Agrostis tenuis, Anthoxanthum alpinum, Carex sempervirens, Festuca rubra, Nardus stricta, Phleum alpinum, Poa alpina, Poa violacea, Alchemilla vulgaris, Leontodon hispidus, Potentilla aurea, Trifolium repens). Wild seeds were collected from plants spontaneously occurring in mountain pastures in North-East Italy and sown in a greenhouse. Plants were transplanted in open main field plots. Each main plot was divided into sub-plots, which were cut (first cut) in succession every 10 days in two consecutive years. Herbage regrowth (second cut) was evaluated at 45, 60 and 75 days after first cut. Herbage samples were analysed for chemical composition, for in vitro organic matter digestibility (OMD), and the NEl content was estimated. During the pasture utilisation period ( i.e., thermic sum between 500 and 1200 °C) the species had limited variation in their average CP contents (81–109 g/kg DM) excluding the lowest values of F. rubra and P. violacea (74 and 71 g/kg DM, respectively; P<0.05) and the highest value of T. repens (202 g/kg DM; P<0.05). Within grasses, there were very fibrous species (>700 g NDF/kg DM, such as F. rubra, N. stricta and P. violacea) and species with medium contents (573–664 g NDF/kg DM), while forbs and the legume specie had a low content (≤403 g NDF/kg DM). The OMD ranged from P. violacea (256 g/kg DM; P<0.05) to T. repens (730 g/kg DM; P<0.05). The highest NEl content was for T. repens (6.3 MJ/kg DM; P<0.05), while low NEl values were calculated for N. stricta and C. sempervirens (2.9 and 2.5 MJ/kg DM, respectively). The lowest (P<0.05) NEl content was estimated for P. violacea (1.9 MJ/kg DM). Most species investigated (in particular, Agrostis tenuis, F. rubra, L. hispidus, Potentilla aurea), had an initial intense decrease in the CP content with advancing season, reaching minimum levels at the thermic sum of 800–1000 °C. During season advancement, all species had increased NDF content, with marked increments for F. rubra and Poa species, and all species had decreased NEl contents. Regrowth samples collected at 75 days after first cut had lower CP and NEl contents relative to those collected after 45 days from the first cut (140 g/kg versus 160 g/kg DM and 4.4 MJ/kg versus 4.8 MJ/kg DM, respectively; P<0.05). This study provides nutritional information on individual herbage species of alpine pastures at different vegetative phases which can be used to obtain average nutritional values of use in pasture management work.

The Rengen Grassland Experiment: Plant species composition after 64 years of fertilizer application

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–K 2SO 4. 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.

Antoine de La Sale: La fabrique de l'œuvre et de l'écrivain (Suivi de l'édition critique du 'Traité des anciens et des nouveaux tournois') by Sylvie Lefèvre

MLR, I02.2, 2007 505 sub AND trippe'. But these quibbles notwithstanding, the point ismade that this is a lexically interesting text.Among the additions ofwords, senses, and forms for incorporation into theAND are the following: areole 2305, 2313, 2324; aromatiz adj. I836, I846, I874, 2432; avoler (=envoler) 2473 cf.AND2 avoler, envoler; bersol 'berceau' I225; botre (botre de Cipre; Lat.: botrus Cipri) 7I4; cedar 482, 484; celle '(wine-)cellar' (Lat.: incellam vinariam) 889, 924; certifs adj. pl. 67; cinnamomum (Latinism?) I840; collegiun 2055; commu nite II6; declinance 2222; deflorir 733, 74I; defrire 1208 and passim cf.glossary; despessure, depessure I562, 1565, I58I; destingte (=destincter) 2368; dignaciun 254; eclips 496; entrepretement (=[interpretement]) 3I9, 503; epitalamye I7I; eschekguet I338; escumege I285 (denasalization: not commented on in introduc tion); esgraventer (=agravanter) 2735; estenseler (fig.) I682, I782; excepe (=excepte) 559; fecundite 743, I8o8, 2528; fesselet 689; fistula (Latinism?) I840; freyllete 625 (etc.); Gerarchie (interesting graphy forhierarchie) I023; ipocresie 4; lymuse adj. f. 237;malus (Latinism?) 'apple-tree' 848, 863;mendrage 2597, cf. AND mandrake, mandeglore; meriene s.f. 'meridian' (Lat.: inmeridie) 536, 549;moniles s.pl. (Lat.: monilia) 634; mureles s.f. pl. 635, 646; nanal (=nenil) II3; narde s.f. (Lat.: nar dus) 66i; nuternaus, nutrenaus adj. pl. (Lat.: nocturnos) 132I, I344; opinium 2338; pigmentaire I267, 23I4; pigmentur 2315, 2325; reclinatorie I350, 1375; runtele 2769; speculacium 2549; tastis s. 'sense of taste' I036; tevement (fig.)579; threisun (=traisun) 28I; transitorie 983; trehur (=[traiour]) 'drawer (of bow)' 945; wage 'wave' 478. The glossary, perhaps inevitably selective, caters for many but not all of these. It is preceded by extensive notes (pp. I39-I62), whose particular and invaluable forte isthe provision of textual parallels with sources (notablyWilliam ofNewburgh's strongly Marian Explanatio, the principal direct model for theAnglo-Norman text, p. 12). The text itselfhas been conservatively and well edited. Overall, then, a valuable addi tion to the ANTS series, of a hitherto unpublished, culturally as well as linguistically interesting text.Pourvu que _adoure, asNapoleon's mother might have said. UNIVERSITY OFWALES ABERYSTWYTH D. A. TROTTER Antoine de La Sale: la fabrique de l'ceuvre et de l'Vcrivain (suivi de l'edition critique du 'Traite des anciens et des nouveaux tournois'). By SYLVIE LEFEVRE. (Publi cations Romanes et FranSaises, 238) Geneva: Droz. 2oo6. 456 pp. SwF 120. ISBN 978-2-600-OIOO8-5. In this thoroughly researched book, Sylvie Lefevre recontextualizes and reconsiders both Antoine de La Sale's talent and his corpus. The book's overarching aim is to contest earlier assertions that there have been twoAntoines: the author of theJehan de Saintre and the author of all other works attributed to him. Countering the likes of Werner Soderhjelm, Gaston Paris, and JuliaKristeva, Lefevre posits thatAntoine de La Sale was amultifaceted and talentedwriter, and the sum of his works point to a skill previously overlooked. To prove thisassertion, Lefevre divides her book into twoparts. The firstaddresses in detail several ofAntoine's works, including theChantilly 924 manuscript of the Paradis de la reine Sibylle, the BnF, n.a. fr. I0057 (F) containing yean de Saintre, Florian etElvide, and Adicion extraicte des Croniques de Flandres, and the Brussels BR I82 I0 -I5ofLa Salade. Through a careful examination of these and othermanu scripts, Lefevre pieces together inscriptions, dedications, signatures, colophons, and short textual excerpts in order to create a complicated puzzle that ultimately re presents Antoine's life and works. In her reading of the Chantilly manuscript, for 506 Reviews instance, Lefevre scrutinizes the dedicatory page, fromwhich she decodes a series of signs that indicate both Antoine's lineage and his future: she examines a coat of arms of thede La Sale family,she compares the signature on thepage with other signatures known to be byAntoine, and she evaluates Antoine's personal devise: 'il convient'. Lefevre also writes in detail about Antoine's La Salade, arguing that this text is richer than other critics have allowed. In fact, shemaintains that it is the very eccen tricitiesand anomalies of the work that make itunique andworth examining. She notes that theconceit ofLa Salade-a text thatcomprises various styles-demonstrates An toine's ability tomove across genres. La Salade also exemplifies Antoine's authorial dexterity-at times he...

A field assessment of the success of moorland restoration in the rehabilitation of whole plant assemblages

AbstractQuestion: How successful is restoration that is focused on a single dominant plant at enabling the reassembly of the whole vegetation assemblage and what factors affect the relative success of such restoration?Location: Moorlands in England and Scotland, UK.Methods: Vegetation composition was sampled in grassdominated (degraded), restored and long established Calluna vulgaris‐dominated (target) areas within eight moorland restoration sites. Additional soil and biogeographic data were collected. Data were analysed by Canonical Correspondence Analysis, which allowed the impact of moorland management to be examined.Results: All sites showed good restoration success when the dominant managed species (Calluna vulgaris, Molinia caerulea and Nardus stricta) were considered. Restoration success of the remainder of the plant assemblage, disregarding these dominant species, was lower with restored samples at some sites differing little from their respective degraded samples. Moors restored solely by grazing exclusion were more similar to their respective targets than were those restored by more intensive mechanical means. The most important factors in explaining vegetation assemblages were management status (i.e. whether samples represented degraded, restored or target parts of the moor) and latitude.Conclusions: The project demonstrates that, where possible, restoration should be attempted by grazing exclusion alone. Furthermore the importance of applying local restoration targets and of monitoring the whole plant assemblages when assessing the success of moorland restoration is highlighted.

Revisiting a 37 years abandoned fertilizer experiment on Nardus grassland in the Czech Republic

A set-aside experiment on sub-alpine Nardo-Caricion rigidae grassland was identified in the Giant Mts. (Krkonos ye, Karkonosze), in which Ca, N and P fertilizers were each applied at three rates on five occasions from 1965 to 1967; since that time plots remained abandoned. In 2004, the effect of all fertilized treatments on sward structure was still visible 37 years after the last fertilizer application. Avenella flexuosa and Anthoxanthum alpinum were the dominant species in phosphorus fertilized plots whereas Nardus stricta was the dominant species in the control as well as in the limed and nitrogen fertilized treatments. The biomass production of A. alpinum was higher in all fertilized treatments than in the control but significantly only in one P treatment. The lowest amount of dead aboveground biomass was found in all P fertilized plots followed by two Ca treatments. P, Ca and NO3 concentrations in the biomass were highest in P treatments and Ca concentration was higher, but non-significantly differing from control, also in two Ca treatments. Soil pH was highest in two Ca treatments and was affected by soil Ca concentration. # 2006 Elsevier B.V. All rights reserved.

Impacts of summer ozone exposure on the growth and overwintering of UK upland vegetation

The effects of ozone exposure on species of an upland grassland were assessed. Thirty-three species from Snowdonia, North Wales, UK, were exposed for 10 weeks to a weekly episodic ozone regime in solardomes representing predicted future concentrations. Two solardomes were used as controls, with ozone added to charcoal-filtered air to give a continuous ozone concentration of 30 ppb (O 3(30)). A weekly episodic ozone regime was applied to two other solardomes, with concentrations rising for 8 h per day to 80 ppb on day 1, 100 ppb on days 2 and 3, and 80 ppb on day 4; ozone concentrations remained at 30 ppb at all other times (O 3(30+peaks)). The control and background ozone concentrations of 30 ppb were maintained throughout the night as well as during the daytime. During exposure to the episodic ozone regime, some species were sensitive to ozone and showed ozone-specific leaf injury symptoms (e.g . Carex echinata) and/or premature senescence (e.g. Festuca rubra) and/or changes in above-ground biomass (e.g. Armeria maritima), whereas other species (e.g Holcus lanatus and Carex demissa) showed no effects. Some species, although showing no effects during the 10-week ozone exposure, showed carry-over effects on biomass the following spring, after a winter period of ambient ozone exposure (e.g. Galium saxatile, Nardus stricta and Saxifraga stellaris). The carry-over effects shown in this study indicate the potential ecological impact of ozone on semi-natural vegetation species and indicate the importance of longer-term studies on the effects of ozone on plants.

Efficacy of graminicides on grass weed species of forestry

Good crop selectivity makes the use of graminicides an attractive proposition for use in tree establishment. However when compared to the agricultural situations upon which most graminicide recommendations are currently based, regenerating woodlands usually contain larger specimens of a wider range of grass weed species. For this reason, five field experiments were set up to investigate the relative susceptibility of young and established plants of 29 grass weed species and Juncus effusus to the graminicides cycloxydim, fluazifop- p-butyl and propaquizafop in comparison with glyphosate and propyzamide. Graminicide applications were made 6, 12 and 18 months after establishing small plants in early autumn. Generally, a wider range of grass species appeared to be susceptible, and at later growth stages, than currently recommended by manufacturers. Cycloxydim was the most effective graminicide on perennial grasses giving good long term control of Anthoxanthum oderatum, Cynosurus cristatus, Dactylis glomerata, Festuca arundinacea, Lolium perenne, Molinia caerulea, Phleum pratense and Poa trivialis at all application dates and Agrostis gigantea, Agrostis stolonifera, Arrhenathrum elatius in spring only. Fluazifop- p-butyl was the most effective on Festuca pratensis. Autumn applications of cycloxydim and fluazifop- p-butyl controlled Holcus lanatus and cycloxydim controlled Agrostis capillaris, Deschampsia caespitosa and Nardus stricta. Propaquizafop was the most effective graminicide on Elytrigia repens. Festuca longifolia, Festuca ovina, Festuca rubra ssp. rubra and J. effusus were not susceptible to these herbicides. The graminicides were generally very effective on annual species except Poa annua, although cycloxydim gave poorer control of older plants of Anisantha sterilis and Anisantha diandra and propaquizafop of Apera spica-venti. Possible factors affecting susceptibility of grass species to these herbicides are reviewed.

Snow Depth and Vegetation Pattern in a Late-melting Snowbed Analyzed by GPS and GIS in the Giant Mountains, Czech Republic

A large, late-melting snowbed and famous landmark was analyzed on a south-facing slope in the Giant (Krkonose/Karkonosze) Mountains, the High Sudetes, Czech Republic. So far, only its maximum snow depth, reportedly between 4 and 20 m, had been merely estimated. Wire probes can be reliably used up to snow depths of 3 m only. To get more realistic data, two digital models using kinematic carrier phase–based GPS measurements were developed: (1) a model for snow surface data, applied at the end of five winter seasons from 2000 to 2004, and (2) a model for the underlying snow free ground surface, applied after the snow melt in August 2000. These two models, overlaid in the GIS environment, have identified snow depths for each of the 111 phytosociological relevés in plots 2 m × 2 m in size. The snow depth maxima recorded in the above given winter seasons were 15.7, 6.1, 13.4, 7.6, and 14.2 m, respectively. To determine the effect of the obtained variables on the vegetation pattern, the relevant snowpack thickness together with snow melting rate, position of the relevé, amount of soil skeleton, depth of litter horizon, and depth of the soil profile were used as environmental variables in the Canonical Correspondence Analysis (CCA), which explained 23.1% of the species data variability. The most powerful environmental variables were soil parameters. The vegetation cover significantly decreased as a function of the snow depth. The tiny forb Gnaphalium supinum and the grasses Avenella flexuosa, Deschampsia cespitosa, and Nardus stricta appeared to be the most tolerant species surviving under the deep snow layer and possessing a short vegetation season. Comparison with an earlier study suggested a stabilized pattern of the snow-patch vegetation even after about 50 years.

A field assessment of the success of moorland restoration in the rehabilitation of whole plant assemblages

Question: How successful is restoration that is focused on a single dominant plant at enabling the reassembly of the whole vegetation assemblage and what factors affect the relative success of such restoration? Location: Moorlands in England and Scotland, UK. Methods: Vegetation composition was sampled in grassdominated (degraded), restored and long established Calluna vulgaris-dominated (target) areas within eight moorland restoration sites. Additional soil and biogeographic data were collected. Data were analysed by Canonical Correspondence Analysis, which allowed the impact of moorland management to be examined. Results: All sites showed good restoration success when the dominant managed species (Calluna vulgaris, Molinia caerulea and Nardus stricta) were considered. Restoration success of the remainder of the plant assemblage, disregarding these dominant species, was lower with restored samples at some sites differing little from their respective degraded samples. Moors restored solely by grazing exclusion were more similar to their respective targets than were those restored by more intensive mechanical means. The most important factors in explaining vegetation assemblages were management status (i.e. whether samples represented degraded, restored or target parts of the moor) and latitude. Conclusions: The project demonstrates that, where possible, restoration should be attempted by grazing exclusion alone. Furthermore the importance of applying local restoration targets and of monitoring the whole plant assemblages when assessing the success of moorland restoration is highlighted.

Fertilizing and liming in a heather area of Norway

In a 6 years’ field experiment in a podzolized heather area in Norway the effects of liming and P and Cu fertilization were tested versus changes in vegetation and soil chemistry. The vegetation altered slowly, particularly the woody species, but pronounced over years. Liming had a positive effect on all species except Deschampsia flexuosa and Vaccinium myrtillus, P tended to favour all except V. myrtillus, and Cu promoted all except Nardus stricta, V. oliginosum and V. myrtillus. Surface spreading of liming material and fertilizers caused distinct lime, phosphorus and copper effects and interactions in the soil litter layer. Liming markedly increased pH and Ca level and stimulated microbial activity, whilst the fertilizers increased P and Cu availability in soil. Cu fertilization counteracted a feared Cu deficiency when liming marginal soils. Gradually the changes penetrated into deeper soil layers. This strong chemical influence led the podzol into a cambisol cycle, characterized by retention of humus in the E layer, accompanied by a slight increase in pH, elevated levels of Kjeldahl-N, AL dissolved and exchangeable Ca, and in CEC and BS.

The diet of field volesMicrotus agrestis at low population density in upland Britain

Studies on field volesMicrotus agrestis Linnaeus, 1758 in lowland grasslands have shown them to be unselective grazers. The diet of the field vole in upland Britain was investigated using feeding trials with four of the dominant British upland monocots,Molinia caerulea,Nardus stricta, Deschampsia flexuosa and Eriophorum vaginatum. The suitability of faecal analysis was assessed and then used to analyse the diet of wild voles from faecal samples. Percentages of plant species in the faeces were compared to percentages on the ground in sites dominated byMolinia caerulea, Eriophorum vaginatum,Nardus stricta andCalluna vulgaris. Significant preferences for the grassDeschampsia flexuosa were observed in feeding trials and in the wild while the sedgeEriophorum vaginatum was avoided in both. There was no clear preference forMolinia caerulea andNardus stricta. Preference for plant species was related to palatability and nutrient content. The low nutrient conditions in British uplands mean that voles that live in these environments must be selective feeders to maximise nutrient intake.