New similarity indices for the assignment of relevés to the vegetation units of an existing phytosociological classification

Every proposed vegetation classification is sooner or later confronted with an accumulation of new data, which has to be assigned to existing vegetation units. Calculation of similarity indices between new relevés (vegetation plots) and constancy columns of established vegetation units is a suitable method for computerised assignment of relevés to these units. This paper compares several similarity indices using simulated data set where either randomly distributed or diagnostic species prevail in the species composition of the tested relevé. Traditional indices, based only on species composition, produce different results than similarity indices that consider species fidelity. However, both types of indices failed in some situations and thus cannot be widely accepted as suitable methods of additional relevé assignment. Therefore a combined Frequency-Positive Fidelity Index (FPFI) is proposed. This new index includes compositional similarity of an assigned relevé with vegetation unit and retains the advantages and lacks the disadvantages of tested indices. The calculation of all these indices is available in the JUICE program (http://www.sci.muni.cz/botany/juice.htm).     

Establishment of Picea abies seedlings in a central European mountain grassland: an experimental study

Abstract. Secondary meadows in the Kru?né hory mountains, central Europe, are not colonized by woody species, although they have been abandoned for half a century and are surrounded by Picea abies (Norway spruce) forests. The causes of inhibition of establishment of Norway spruce seedlings in the meadows were tested experimentally. The experiment was started in a masting year to ensure sufficient seed input. Four treatments (vegetation cut; vegetation cut and litter removed; all above-ground biomass and topsoil removed; control) were combined in a factorial design. The effect of browsing, mainly by deer, was assessed by fencing half of the experimental plots. Seedling establishment differed among treatments (all pair-wise differences were significant) but was independent of fencing. In contrast, seedling survival was influenced both by the treatment and fencing. At the end of the second year, only the plots with all biomass and organic topsoil removed supported viable populations of spruce seedlings. Dense herb cover and a thick layer of slowly decaying litter are considered the main factors inhibiting the establishment of woody species.     

Recent changes in the plant composition of wetlands in the Jura Mountains

Aim

To assess vegetation changes in montane fens and wet meadows and their causes over 38 years.

Location

Wetlands, Jura Mountains (Switzerland and France).

Methods

Plots were inventoried in 1974 and re‐located in 2012 (quasi‐permanent plots) on the basis of sketches to assess changes in plant communities. The 110 plots belonged to five phytosociological alliances, two in oligotrophic fens (Caricion davallianae, Caricion fuscae) and three in wet meadows (Calthion, Molinion, Filipendulion). Changes between surveys were assessed with NMDS, and changes in species richness, Simpson diversity, species cover and frequency and the causes of these changes were evaluated by comparing ecological indicator values.

Results

Changes in species composition varied between alliances, with a general trend towards more nutrient‐rich flora with less light at ground level. Species diversity declined, with a marked decreasing trend for the typical species of each alliance. These species were partly replaced by species belonging to nitrophilous and mesophilous grasslands. However, no trend towards drier conditions was detected in these wetlands. The largest changes, with an important colonization by nitrophilous species, occurred in the Swiss sites, where grazing was banned 25 years ago. As a result of floral shifts, many plots previously belonging to fens or wet mesotrophic meadows shifted to an alliance of the wet meadows, generally Filipendulion. Moreover, communities showed a slight trend towards more thermophilous flora.

Conclusions

The investigated wetlands in the Jura Mountains have suffered mainly from eutrophication due to land‐use abandonment and N deposition, with a loss of typical species. Areas with constant land use (grazing or mowing) showed less marked changes in species composition. The most important action to conserve these wetlands is to maintain or reintroduce the traditional practices of extensive mowing and livestock grazing in the wetlands, especially in areas where they were abandoned 25 years ago. This previous land‐use change was intended to improve fen conservation, but it was obviously the wrong measure for conservation purposes.     

Phytosociology and ecology of old hay meadows in Hordaland,western Norway in relation to management

Well-drained mown hay meadows in Hordaland, western Norway, were investigated. The hay meadows are either managed in a traditional or in a semi-traditional way. Traditional management in the area involves little or no use of manure or fertilizer, mowing once or twice a year with a first cut later than June 23, clearing in spring and intensive grazing for short periods in spring and autumn. Semi-traditional management involves use of small to medium quantities of commercial fertilizer, often in addition to manure. Grazing may be irregular, light or lacking.Eight units of hay meadow vegetation are described, all assigned to the class Molinio-Arrhenatheretea, order Arrhenatheretalia; four units to the Atlantic alliance Cardaminion pratensis, association Cardamino pratensis-Conopodietum majoris (with three subassociations); one unit to the alliance Arrhenatherion elatioris, three units are provisionally grouped as Galium uliginosum-Knautia arvensis meadows.Continuous management of these meadows has resulted in characteristic species compositions, which vary along a west-east climatic gradient, and are related to the amount of commercial fertilizer used and the natural mineral-content of the soil.These hay meadows seem to be best maintained by continuing the traditional management regime. Grazing in spring and in autumn reduces fast growing dominants and creates openings for new seedlings of annuals and biennials. A late first cut allows for ripening of the seeds and creates openings for light for the species of the lower field layer. A list of species characteristic of traditionally managed permanent hay meadows is presented, and possible effects of present changes in management on the species composition of the meadows are discussed.The amount of organic matter in the topsoil is small in most stands. The pH values are between 4.0 and 5.6. The highest values were recorded in soil where little or no commercial fertilizer is used, and where the subsoil is naturally rich in minerals. A tendency to Mg impoverishment in the best fertilized stands is demonstrated. Species-rich stands on Ca-rich soils are poor in P.The expected changes in vegetation, future use, and conservation of permanent hay meadows in Hordaland are discussed.     

Plant community response to nitrogen and phosphorus enrichment varies across an alpine tundra moisture gradient

Background: The extent to which nutrient availability influences plant community composition and dynamics has been a focus of ecological enquiry for decades.

Aims: Results from a long-term nitrogen (N) and phosphorus (P) addition experiment in alpine tundra were used to evaluate the importance of the two nutrients in structuring plant communities in three communities that differed in their snow cover amounts and duration and soil moisture characteristics.

Methods: A factorial N and P experiment was established in three meadows differing in initial vegetation composition and soil moisture. Plant and soil characteristics were measured after 20 years, and the dissimilarity among meadows and treatments were measured using permutational analysis of variance.

Results: Plant species richness declined uniformly across the three meadow types and in response to N and N + P additions, while both evenness and the Shannon diversity index finding indicated that nutrient additions had the highest impact on moister habitats. Overall, N impacts overshadowed changes attributed to P additions, and the N and N + P plots in wet meadow sites were the least diverse and scored the lowest dissimilarity averages among treatments. Dissimilarity estimates indicated that the control and P plots in the dry meadow community were more distinct in composition than all other plots, and especially those in the moist or wet meadows. Above-ground biomass of grasses and sedges (graminoids) increased with N additions while forbs appeared to show responses dictated in part by the graminoid responses. The most abundant grass species of moist and wet meadow, Deschampsia cespitosa, dominated N and N + P plots of the wet sites, but did not show a N response in moist areas in spite of its general abundance in moist meadow. Competition from other plant species in the moist areas likely diminished the D. cespitosa response and contributed to the resilience of the community to nutrient enrichment.

Conclusions: Initial community composition, as influenced by the specific moisture regime, appears to control the extent to which changes in nutrient resources can alter plant community structure. Long-term fertilization tends to support most but not all findings obtained from shorter-termed efforts, and wet meadows exhibit the largest changes in plant species numbers and composition when chronically enriched with N.     

Management of Phragmites australis in Swiss fen meadows by mowing in early summer

Mowing experiments were carried out from1995 to 2001 in Swiss fen meadows toinvestigate whether the abundance of Phragmites australis is reduced by mowingin early summer in addition to mowing inautumn. Experimental plots of 100 m²were established in three fen meadows thatare mown every year in September; treatedplots received an additional cut in lateJune either every year or every two years.Until 1997, the additional cut had noeffect on the above-ground biomass of Phragmites (monitored every year in lateJune). As from 1998, the biomass of Phragmites was 25–30% lower in the plotswith annual June cut than in the controlplots. However, the pooled biomass of allother plant species decreased similarly, sothat the degree of dominance of Phragmites was not reduced. An additionalJune cut every two years had no effect onthe biomass of Phragmites. In June2001, the shoots of Phragmites weresmaller in annually June-cut plots than incontrol plots, but allometric relationshipsbetween shoot length and diameter, shootgrowth from June to August, and nitrogenand phosphorus concentrations of shoots didnot differ between June-cut and controlplots. The additional June cut increasedthe total export of N with the hay by 18%,and that of P by 50% in 2001. Theseadditional nutrient exports were smallerthan those found in the first years of theexperiment and not larger for Phragmites than for the remainder of thevegetation. Together, the results suggestthat a depletion of below-ground storescaused Phragmites to decrease afterseveral years of additional mowing in June.Eighty further permanent quadrats in fenmeadows with normal management (mownannually in September) were surveyed in1995–96 and in 2001. The above-groundbiomass of Phragmites increasedduring this time in 49 out of 80 plots,with a mean relative difference of +35.5%.Thus, even if additional mowing in earlysummer only slightly reduced theperformance of Phragmites compared toplots mown only in September, thistreatment might help to prevent the speciesfrom spreading under the current conditionsin Swiss fen meadows.     

Les pelouses à Festuca paniculata du Tessin (Suisse) dans un contexte Alpin

Vittoz P., Selldorf P., Eggenberg S. and Maire S. 2005. Festuca paniculata meadows in Ticino (Switzerland) and their Alpine environment. Bot. Helv. 115: 33–48.Festuca paniculata (L.) Schinz & Thellung locally dominates montane and subalpine meadows of the Alps and other mountains of southern Europe. Vegetation relevés were carried out in Switzerland and northern Italy to study the site conditions under which Festuca paniculata meadows occur in this part of the Alps, their species composition and phytosociological status, and their relationship to Festuca paniculata meadows described previously from the French Alps (Centaureo-Festucetum spadiceae) and Austrian Alps (Hypochaerido uniflorae-Festucetum paniculatae). The Swiss meadows were found to have a similar ecology to those in France and Austria. They occur mostly between 1600 and 2100 m a.s.l on steep slopes with southern aspect, generally on crystalline rocks, but sometimes on calcareous rocks if soils have been decalcified. The species composition of the Swiss meadows is closer to the Austrian than to the French communities, and we attribute them to the association Hypochaerido uniflorae-Festucetum paniculatae with the new subassociation polygaletosum chamaebuxi. Climate is probably the main factor separating vegetation units in the Alps: the Centaureo-Festucetum spadiceae occurs where summers are dry, whereas the Hypochaerido uniflorae-Festucetum paniculatae occurs where rainfall is not a limiting factor in summer.Manuscrit accepté le 10 février 2005     

Plant biomass and species composition along an environmental gradient in montane riparian meadows

In riparian meadows, narrow zonation of the dominant vegetation frequently occurs along the elevational gradient from the stream edge to the floodplain terrace. We measured plant species composition and above- and belowground biomass in three riparian plant communities—a priori defined as wet, moist, and dry meadow—along short streamside topographic gradients in two montane meadows in northeast Oregon. The objectives were to: (1) compare above- and belowground biomass in the three meadow communities; (2) examine relations among plant species richness, biomass distribution, water table depth, and soil redox potential along the streamside elevational gradients. We installed wells and platinum electrodes along transects (perpendicular to the stream; n=5 per site) through the three plant communities, and monitored water table depth and soil redox potential (10 and 25 cm depth) from July 1997 to August 1999. Mean water table depth and soil redox potential differed significantly along the transects, and characterized a strong environmental gradient. Community differences in plant species composition were reflected in biomass distribution. Highest total biomass (live+dead) occurred in the sedge-dominated wet meadows (4,311±289 g/m²), intermediate biomass (2,236±221 g/m²) was seen in the moist meadow communities, dominated by grasses and sedges, and lowest biomass (1,403±113 g/m²) was observed in the more diverse dry meadows, dominated by grasses and forbs. In the wet and moist communities, belowground biomass (live+dead) comprised 68–81% of the totals. Rhizome-to-root ratios and distinctive vertical profiles of belowground biomass reflected characteristics of the dominant graminoid species within each community. Total biomass was positively correlated with mean water table depth, and negatively correlated with mean redox potential (10 cm and 25 cm depths; P <0.01) and species richness (P <0.05), indicating that the distribution of biomass coincided with the streamside edaphic gradient in these riparian meadows.Electronic Supplementary Material Supplementary material is available in the online version of this article at     

Effectiveness of Turf Stripping as a Measure for Restoring Species-Rich Fen Meadows in Suboptimal Hydrological Conditions

Most species‐rich fen meadows in nature reserves in The Netherlands are acidified due to weaker upwelling of base‐rich groundwater. The present study investigated whether and why turf stripping combined with superficial drainage might promote the long‐term recovery of such meadows and restore the nutrient‐poor, buffered conditions they require. In a field experiment, we analyzed changes in vegetation composition, soil parameters, and soil water chemistry in stripped plots of degraded Cirsio‐Molinietum vegetation over 12 years. After the first five years, many species from the target communities occurred in stripped plots. Both vegetation and soil data showed positive effects of turf stripping on the acid‐buffering capacity. Because sulfate concentration in the soil water decreased over time, whereas the bicarbonate concentration increased, we inferred that there was internal alkalinization driven by sulfate reduction in low‐lying stripped plots. However, the succession toward more acidophilus plant communities, in both control and stripped plots, indicated gradual acidification. This may be caused by a continuing weakening of the upward seepage of base‐rich groundwater as shown by declining calcium concentrations in the soil water. Though turf stripping exposed a nutrient‐poor soil layer with a greater acid‐buffering capacity, these positive effects might not be sufficient to combat the ongoing acidification in the long term.     

A method for the analysis of temporal changes in vegetation pattern at the landscape level

A new approach to study temporary changes in small landscape units is proposed, based on vegetation-complex relevés (sigma relevés). The method is introduced using extensively grazed or abandoned heathland and Nardus-sward landscapes in the Black Forest as examples. Thirty-six sigma relevés of the years 1979–80 are compared with those of 1989–90. Each of the compared plot areas covers on the average 2–4 hectares, and has a diversity of about 20 different vegetation types. The vegetation complex relevés can be ordered to 3 different types which characterize landscape ecological zones dependant on former rural management.As a result of the comparison 2 main developments which have a spatial differentiation in the Black Forest are confirmed and documentated:

Vegetation changes following sheep grazing in abandoned mountain meadows

Abstract. Sheep grazing was investigated as an alternative to traditional management of meadows in the Krkono?e Mts. Until the second World War these meadows were mown in mid‐summer and grazed by cattle for the rest of the season. Subsequent abandonment of the meadows has resulted in decreasing species richness. Degradation phases of the former communities have been replacing the original species‐rich vegetation. Significant changes were apparent six years after the introduction of sheep grazing. In grazed plots the proportion of dominant herbs (Polygonum bistorta and Hypericum maculatum) decreased and grasses (Deschampsia cespitosa, Festuca rubra, Agrostis capillaris, Anthoxanthum alpinum) increased. The increase in grasses was positively correlated with an increase in several herbs. The proportion of some herbs increased despite being selectively grazed (Adenostyles alliariae, Melandrium rubrum, Veratrum lobelianum). Any losses caused by grazing of mature plants were probably compensated by successful seedling establishment. Cessation of grazing resulted in significant changes in vegetation within three years. The cover of nitrophilous tall herbs and grasses (e.g. Rumex alpestris, Holcus mollis, Deschampsia cespitosa, Geranium sylvaticum) increased in the abandoned plots. In the plots grazed for nine years cover of species‐rich mountain meadow species increased (e.g. fine‐leaved grasses, Campanula bohemica, Potentilla aurea, Viola lutea, Silene vulgaris). The main conservation risk is the expansion of a competitive species with low palatability, Deschampsia cespitosa. This species can be suppressed by a combination of grazing and mowing. In order for grazing to be effective, the number of sheep should be proportional to meadow production. This may be difficult to maintain as production is variable and is impossible to predict at the beginning of a growing season. A large part of the biomass may thus remain intact in some years. Negative effects of grazing may be, at least partly, eliminated by a combination of cutting and grazing.     

How do management and restoration needs of mountain grasslands depend on moisture regime? Experimental study from north‐western Slovakia (Western Carpathians)

Question: How does species composition change in traditionally managed meadows after mowing has ceased, and in abandoned meadows after re‐introduction of mowing? Are there differences in the dynamics of dry and moderately wet meadows? Location: Zázrivá‐Ple?ivá (19°11′N, 49°16′E), north‐western Slovakia, western Carpathians. Methods: Pairs of experimental plots (mown and unmown) were established to replicate each combination of dry/wet and traditionally managed/abandoned meadows. Changes in species composition were studied over 5 years. The data on changes in species composition was analysed by constrained and unconstrained ordinations, and visualized using Principal Response Curves. Results: Species composition of newly abandoned wet grasslands was changing towards the corresponding long‐abandoned plots even in the first year of abandonment. Similarly, newly established restoration mowing in abandoned dry grasslands rapidly shifted the stand species composition towards that of traditionally managed ones. Nevertheless, 4 year after reintroduction of mowing, the species composition of the restored plots was still far from the target composition. The effect of mowing in abandoned wet grasslands and abandonment in dry grasslands was much less pronounced and slower. Conclusions: Moisture regime is a very important factor determining the management needs of various grassland types. Wet grasslands are much more sensitive to abandonment, with a rapid degradation rate and limited possibilities for restoration, which can be extremely slow. Even in the dry grasslands, that quickly responded to restoration mowing, restoration is a long‐term process.     

Reversing expansion of Calamagrostis epigejos in a grassland biodiversity hotspot: Hemiparasitic Rhinanthus major does a better job than increased mowing intensity

Questions

Can hemiparasitic Rhinanthus major originating from a local population suppress the competitive clonal grass Calamagrostis epigejos and reverse its expansion in species‐rich semi‐natural grasslands? Does sowing seeds of R. major facilitate restoration of target meadow vegetation? Is R. major more beneficial for biodiversity restoration/conservation than increased mowing intensity, a conventional measure to suppress C. epigejos?

Location

?ertoryje National Nature Reserve, Bílé Karpaty (White Carpathians) Protected Landscape Area, Czech Republic.

Methods

We conducted a before‐after‐control‐impact experiment in meadow patches heavily infested by C. epigejos: eight blocks, each containing four plots with four treatment combinations: (1) traditional management, i.e. mowing once in summer, (2) mowing in summer and autumn (3) mowing in summer and seed sowing of R. major, (4) mowing in summer and autumn and seed sowing of R. major. Above‐ground biomass of C. epigejos and vegetation composition of each of the plots were monitored every year from 2013 to 2016. To assess the effects of treatments, we analysed biomass production of C. epigejos, herb layer cover and vegetation composition.

Results

Both sowing R. major and an additional autumn meadow cut significantly suppressed C. epigejos. Their effects were additive and of comparable size. Both treatments also had significant but markedly different effects on community composition. Rhinanthus major facilitated directional community composition change towards the regional Brachypodio‐Molinetum meadows. In contrast, increased mowing intensity significantly decreased frequency of threatened species, which however may have also been influenced by R. major.

Conclusions

Sowing of autochthonous R. major seeds was demonstrated as an efficient tool to suppress C. epigejos and facilitate community restoration. It can be combined with an additional meadow cut to further accelerate decline of the grass. The additional cut should however be used as a short‐term practice (1–2 years) only to minimize potential negative effects of its long‐term application on some threatened plant species. The effects of R. major are comparable to those of Rhinanthus alectorolophus reported previously. As a species occurring naturally in species‐rich dry grasslands, R. major has a broader and longer‐term application potential than R. alectorolophus in ecological restoration and conservation of these communities.     

The Role of White Clover in the Loss of Diversity in Grassland Habitat Restoration

A field experiment was designed to recreate a species‐rich mesotrophic grassland community of conservation worth. Trifolium repens (white clover) was observed to increase significantly in both frequency and abundance in sown plots grazed by cattle, but not in plots cut in June and subsequently grazed by cattle. In both these treatments permanent quadrats containing clover patches were found to be lower in species richness than were quadrats without clover. In both treatments botanical diversity was seen to decline over time. In the grazed‐only treatment the loss of diversity may be linked to the increase in clover. In the cut and grazed plots, T. repens did not become so abundant but diversity was still seen to decline, possibly due to the loss of low growing species from the taller sward. A pot experiment which varied the sowing density of a mix of seven wild flower species in full factorial combination with cutting frequency was established on soils from an arable field also sown with a single density of clover. T. repens was seen to decline from initial high cover estimates in infrequently cut and uncut treatments. In the pot experiment where a grass component to the vegetation was absent, clover was seen to have less impact on the other forbs than it did in the field. It is suggested that, being a nitrogen fixer, T. repens may have a competitive edge in ex‐arable soils low in available nitrogen. The observed reduction in botanical diversity may be a result of this increase in available nitrogen, facilitating the spread of the sown grasses and preventing the recovery of the sown forbs that were excluded by the invasion of T. repens. It is suggested that reducing the proportion of grass in the seed mixtures during grassland habitat creation on these soils may help reduce or delay this effect.     

Differences in flooding tolerance between species from two wetland habitats with contrasting hydrology: implications for vegetation development in future floodwater retention areas

Background and Aims

Plants need different survival strategies in habitats differing in hydrological regimes. This probably has consequences for vegetation development when former floodplain areas that are currently confronted with soil flooding only, will be reconnected to the highly dynamical river bed. Such changes in river management are increasingly important, especially at locations where increased water retention can prevent flooding events in developed areas. It is therefore crucial to determine the responses of plant species from relatively low-dynamic wetlands to complete submergence, and to compare these with those of species from river forelands, in order to find out what the effects of such landscape-scale changes on vegetation would be.

Methods

To compare the species'' tolerance to complete submergence and their acclimation patterns, a greenhouse experiment was designed with a selection of 19 species from two contrasting sites: permanently wet meadows in a former river foreland, and frequently submerged grasslands in a current river foreland. The plants were treated with short (3 weeks) and long (6 weeks) periods of complete submergence, to evaluate if survival, morphological responses, and changes in biomass differed between species of the two habitats.

Key Results

All tested species inhabiting river forelands were classified as tolerant to complete submergence, whereas species from wet meadows showed either relatively intolerant, intermediate or tolerant responses. Species from floodplains showed in all treatments stronger shoot elongation, as well as higher production of biomass of leaves, stems, fine roots and taproots, compared with meadow species.

Conclusions

There is a strong need for the creation of temporary water retention basins during high levels of river discharge. However, based on the data presented, it is concluded that such reconnection of former wetlands (currently serving as meadows) to the main river bed will strongly influence plant species composition and abundance.Key words: Acclimation, biomass allocation, climate, complete submergence, flooding tolerance, retention areas, shoot elongation, soil flooding, waterlogging, wetland species     

Computerized matching of relevés and association tables,with an application to the British National Vegetation Classification

When a new relevé is to be assigned to a pre-existing type, its composition is compared with an association table. Bayesian inference may seem a good way to make the comparison, but presents difficulties. In an alternative approach, three indices of goodness-of-fit are proposed. Compositional satisfaction is a measure of how well the species composition of the relevé fits the constancy classes in the table; it is a minor modification of the Czekanowski coefficient of similarity between observed and expected numbers of species in each constancy class. Dominance satisfaction is a modification of the Czekanowski similarity between the relevé and cover values that might be expected from the association table. Dominance constancy is a weighted mean of the constancy class of the four most abundant species in the relevé. A computer program, TABLEFIT, combines them into a single index. It has been tested on British mire vegetation.     

Long‐term influence of sod cutting depth on the restoration of degraded wet heaths

Temperate heaths have an unfavorable conservation status in most European biogeographical regions. Increasing nitrogen levels promote competitive grass species such as Molinia caerulea, which is a main threat to heathland conservation in Europe. This article investigates the long‐term influence of sod cutting and the resulting changes in soil properties on the heath composition, integrity, and structure. In 15 nature reserves across the northern half of Belgium, we used (1) a large number of plots (203); (2) a broad range of sod cut depths (2–40 cm), and (3) a temporal dimension that describes how long the effects of sod cutting persist (census up to 19 years after sod cutting). Multivariate analyses were used in order to explore the influence of sod cut depth and time after sod cutting on the soil and vegetation properties. There was a positive relationship between sod cut depth and soil pH and water level, and a negative relationship with Al³⁺, NH₄⁺, and total organic matter (TOM). However, only a limited number of typical (target) species appeared after sod cutting, and then only weakly. Most of the time they remained a minor component of the restored vegetation. Moreover, M. caerulea reappeared and its cover significantly increased during the years following sod cutting. Although we were able to show that sod cut depth has a differential effect on soil properties and vegetation recovery, it also appeared that sod cutting does not restore wet heaths in the long term when applied in regions with high nitrogen deposition.     

Can tissue element concentration patterns at the individual species level indicate the factors underlying vegetation gradients in wetlands?

Question: Do tissue element concentrations at the individual species level vary along major vegetation gradients in wetlands, and can they indicate environmental conditions? Location: West Carpathians. Methods: Total plant species composition was recorded in plots distributed along a poor to rich gradient within spring fens and along the gradient from fens to wet meadows. Eriophorum angustifolium (Cyperaceae) and three broadleaf dicotyledonous herb species were collected from the vegetation plots. Tissue N, P, K, Ca and Fe concentrations, N:P and N:K ratios of the species were determined. Each variable was correlated with the sample scores along the first two axes of the DCA ordination, which represented the two main vegetation gradients. Results: K and Ca concentrations in a particular species correlated well with the vegetation gradients, thus indicating changes in the element availability to the species. The trends were sometimes contradictory to known patterns at the community level, but the differences could be ecologically interpreted. Contrary to Ca and K, patterns in N, P and Fe concentration appeared to be more species‐specific. E. angustifolium had a lower K and Ca concentration than the broadleaf herbs. Conclusions: Compared to community‐level measurements, element concentrations in individual species correlated less with observed vegetation gradients. Trends found at the species level may indicate changes in ecological conditions affecting the species, although they need not correspond with trends found at the community level. We conclude that the species‐level approach cannot substitute, but can advance, the community‐level approach in searching for mechanisms underlying vegetation gradients within wetlands.     

Vegetation changes in restored semi-natural meadows in the Turku Archipelago of SW Finland

In the Turku Archipelago of SW Finland the traditional animal husbandry dramatically decreased in 1950s after which the unused semi-natural pastures and meadows began to develop into less species rich shrub and tree communities. Restoration of some semi-natural meadows and pastures started in the late 1970s. Removing trees and shrubs, grazing, mowing, and pollarding deciduous trees were used as restoration of practises. Vegetation changes were followed from forty-one permanent sample plots established on restored areas. In this paper the data before restoration and 7–8 years after the first monitoring was analysed with parametric tests. The sample plots were divided into three restoration groups where the main restoration practises were: group 1. grazing, group 2. thinning (clearing plots from shrubs and removing some trees), group 3. thinning, mowing, and grazing (old wooded meadows). The results showed that: (1) The vegetation changed during analysed time. The number of species increased in all restored areas even though the changes were more pronounced in grazed areas and wooded meadows than in thinned areas. During restoration many common herb and grass species immigrated into the sample plots, but very few new indicator species of meadows were recorded. Most of the new species were found in few numbers in a sample plot which led to the significant increase in the number of sparse species (percentage cover < 1) in all restoration groups. The grasses benefited more from the restoration than herbs increasing their percentage cover significantly in grazed areas and in wooded meadows. In thinned areas the total percentage cover of the ten most dominant herb and grass species increased significantly. (2) The different restoration groups changed vegetation quite similarly. In grazed areas and in wooded meadows significant changes were slightly more numerous than in thinned areas. (3) The differences between the islands in vegetation changes were not pronounced. The added variance components among islands increased during restoration which probably indicated that the restoration practises as well as the species pool of the islands influenced the success of restoration.     

Grazing‐induced changes in plant–soil feedback alter plant biomass allocation

Large vertebrate herbivores, as well as plant–soil feedback interactions are important drivers of plant performance, plant community composition and vegetation dynamics in terrestrial ecosystems. However, it is poorly understood whether and how large vertebrate herbivores and plant–soil feedback effects interact. Here, we study the response of grassland plant species to grazing‐induced legacy effects in the soil and we explore whether these plant responses can help us to understand long‐term vegetation dynamics in the field. In a greenhouse experiment we tested the response of four grassland plant species, Agrostis capillaris, Festuca rubra, Holcus lanatus and Rumex acetosa, to field‐conditioned soils from grazed and ungrazed grassland. We relate these responses to long‐term vegetation data from a grassland exclosure experiment in the field. In the greenhouse experiment, we found that total biomass production and biomass allocation to roots was higher in soils from grazed than from ungrazed plots. There were only few relationships between plant production in the greenhouse and the abundance of conspecifics in the field. Spatiotemporal patterns in plant community composition were more stable in grazed than ungrazed grassland plots, but were not related to plant–soil feedbacks effects and biomass allocation patterns. We conclude that grazing‐induced soil legacy effects mainly influenced plant biomass allocation patterns, but could not explain altered vegetation dynamics in grazed grasslands. Consequently, the direct effects of grazing on plant community composition (e.g. through modifying light competition or differences in grazing tolerance) appear to overrule indirect effects through changes in plant–soil feedback.