Tuexenia : Mitteilungen der Floristisch-Soziologischen Arbeitsgemeinschaft, Band 36 (2016)
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- species richness (4)
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Halting the loss of grassland biodiversity and restoring degraded ecosystems are high priority tasks in the EU Biodiversity Strategy. Sowing low-diversity seed mixtures is widely used in grassland restoration because of its high predictability and fast, promising results. Generally, the sown perennial grasses establish within a few years and form a dense sward, which effectively suppresses weeds. Unfortunately, these grasslands are often species-poor because the sown grasses hamper the colonisation of target grassland forbs. Our aim was to test a novel approach to increase the diversity of species-poor grasslands. We selected eight 8-year-old grasslands restored by low-diversity seed sowing where we created 32 establishment gaps by breaking up the grass sward and sowing a high-diversity seed mixture (35 native species). Altogether, we established three grazed gaps (1m × 1m, 2m × 2m and 4m × 4m) and one fenced gap (4m × 4m) per site and monitored the presence and abundance of sown and non-sown species within a time frame of two years. We asked the following questions: (1) Which target species establish most successfully? (2) What is the effect of establishment gap size on the establishment success of target species and weeds? (3) What is the effect of management (grazed versus not managed) on the species composition of the establishment gaps? Our results showed that by creating establishment gaps and sowing diverse seed mixtures, we were able to overcome microsite and propagule limitation, successfully introducing target species into the species-poor grasslands. We found that all sown species established in the gaps, and the majority of the species maintained or even increased their first-year cover in the second year. Smaller gaps were characterised by lower cover of sown species and a quite stochastic development compared to the larger ones. Weed cover was moderate in the first year and decreased significantly in the second year, regardless of gap size. Therefore, in restoration practice, the use of larger establishment gaps is recommended. We found that the cover of sown species and weeds were similar in the grazed and unmanaged gaps during our study. However, management by extensive grazing might be crucial in the long-term because livestock can disperse target species propagules and create microsites. Our study shows that establishment gaps can serve as biodiversity hotspots. Further studies need to clarify to what extent they can improve the restoration success across the entire grassland.
Im östlichen Südtirol wurden Wiesen entlang der Gradienten Meereshöhe, Bodenfeuchtigkeit, Bewirtschaftungsintensität über saurem bzw. basischem Gestein erhoben und in 12 Vegetationstypen gegliedert. Sie wurden durch numerische Syntaxonomie bzw. den rechnerischen Vergleich mit einer Auswahl von Tabellen aus der Literatur den entsprechenden Pflanzengesellschaften zugeordnet. Aus den Beschreibungen der jeweiligen Syntaxa wurde die Bewirtschaftungsintensität abgeleitet. Dies führte zur Differenzierung von extensiven (ungedüngten), halbintensiven (schwach bis mäßig gedüngten, ohne flüssige Wirtschafts- und Mineraldünger) und intensiven (reichlich gedüngten, meist mit Gülle) Wiesentypen. Da sich die Stickstoffzahlen signifikant unterschieden, stellen die Wiesentypen zuverlässige Indikatoren für die jeweiligen Bewirtschaftungsintensitäten dar. Intensivwiesen wiesen mittlere Stickstoffzahlen über 6,0 auf und wurden dem Poo-Trisetetum poetosum trivialis zugeordnet, halbintensive Wiesen mit Stickstoffzahlen zwischen 4,0 und 5,0 gehören dem Poo-Trisetetum arrhenatheretosum, dem Trisetetum flavescentis typicum bzw. -nardetosum und dem Angelico-Cirsietum oleracei an. Extensive Wiesen hatten durchschnittliche Stickstoffzahlen unter 4,0 und gehören dem Potentillo erectae-Brachypodietum pinnati brometosum erecti und -avenuletosum praeustae, dem Sieversio-Nardetum strictae typicum und -festucetosum nigricantis, dem Carlino-Caricetum sempervirentis, dem Campanulo scheuchzeri-Festucetum noricae und der Scheuchzerio-Caricetea fuscae-Gesellschaft an. Die extensiven und halbintensiven Pflanzengesellschaften entsprechen traditionell bewirtschafteten Wiesen, die eine größere Artenvielfalt und Variation an Vegetationstypen aufweisen als der floristisch triviale Intensivwiesentyp.
Inland sand vegetation, in our case steppic sandy grassland on base-rich soils, is highly endangered in Europe and therefore in the focus of restoration ecology. While there are studies which deal with short-term restoration success, results for an extended time are rare. We were able to analyse the success of a three-step restoration measure for 10 years.
The experiment was established on an exarable field in the Upper Rhine valley, Hesse, Germany. The three-step restoration approach comprised 1) abiotic restoration by deep-sand deposition, 2) inoculation with raked/mown plant material from two different donor sites with well-developed Koelerion glaucae/Allio-Stipetum vegetation and 3) low-intensity grazing by donkeys. The vegetation of the restoration and donor sites (also serving as reference sites to assess restoration success) was sampled on six permanent plots, respectively. Data analyses included ordination, classification and target-species ratios (TSR: relation of target species to all species).
Detrended correspondence analysis revealed a continuous succession of the restoration plots towards the corresponding reference plots: open soil decreased, ruderal species declined and target species increased. While speed of succession decreased, there was still a further improvement in the tenth year. The qualitative TSR (number of target species) reached a plateau after the sixth year with values only slightly lower than at the reference sites. The quantitative TSR (cover of target species) showed a steady improvement and even excelled one reference site. Koelerion glaucae species were present with constancy 17–67% since the 3rd year, with 33–100% since the 7th year. It does not completely resemble either reference site due to a mixture of propagules of both donor sites (e.g. by wind and donkeys) and input from the surroundings. Already in the first year, three Red-list species established themselves, since the 8th year 23 Red-list/near-threatened species have been present. Some ruderal species colonised the restoration site and occurred permanently.
Additionally, we studied the establishment of the highly threatened species Bassia laniflora after inoculation for 6–12 years on three further plots adjacent to the other ones. One of these plots was located on a former sandy field without abiotic restoration; two other plots represented typical Koelerion glaucae vegetation on a newer deep-sand deposition. Bassia laniflora established itself well on all plots. We conclude that restoration of steppic sandy grassland, including highly threatened species, was not only permanently, but increasingly successful over a time span of 10 years. Management by grazing, however, will remain essential to suppress ruderalisation.
Semi-dry grasslands were once widely distributed communities, but today they represent some of the most vulnerable habitats in Central Europe. European and national legislation and non-governmental organizations have managed to protect some of the remaining fragments. However, despite their status as Natura 2000 habitats, they are often endangered due to improper management, fragmentation and edge effects from adjacent croplands. By using a sample of 44 semi-dry hay meadows in the south-eastern Alpine Foreland of Styria, we investigated how species-richness and trait composition of semi-dry grassland species respond to variation in patch size, connectivity, abiotic site factors and management regimes. We used linear regression models to identify the most important drivers for richness of typical semi-dry grassland species and thus conservation value. The number of typical semi-dry grassland species was highest in well-connected fragments, i.e. units that shared two or more borders with neighbouring species-rich grasslands. Furthermore, large semi-dry grasslands (> 8000 m²) had highest numbers of semi-dry grassland species and highest relevance for conservation; no difference was found among smaller fragment sizes. Unregular management was associated with increased presence of competitive species which replaced stress-tolerant specialists. Our study indicates that under eutrophication, small fragment size and isolation, only large semi-dry grasslands can sustain a high number of species with high conservation value. The conservation value of smaller semi-dry grassland fragments could be improved by buffer zones, adapted mowing treatments and periodical sheep grazing.
The degradation of species-rich mountain meadows has been observed in many parts of Central Europe in the last few decades. It is reflected in decreasing species numbers and changes in the proportions of plant species in the aboveground vegetation. Some species are increasing in abundance and eventually dominate the meadow vegetation. There is still a lack of studies explaining how this process is reflected in the soil seed bank. Therefore, the goal of the current study was to test whether expansive species that degrade aboveground vegetation of mountain meadows also influence, quantitatively and qualitatively, seed rain and seed bank. Soil samples were taken from 14 plots in degraded patches and another 14 plots in non-degraded patches. Nearly the same numbers of seedlings were recorded in both meadow types. In both cases, low similarities between aboveground vegetation and soil seed rain and seed bank were observed. Expansive species causing meadow degradation (Calamagrostis epigejos, Festuca rubra, Deschampsia cespitosa and Lupinus polyphyllus) reached cover values of 60–83% in the aboveground vegetation, and a share of up to 36% in the seed rain and seed bank. The mean species richness in the aboveground vegetation and the soil of degraded meadows was lower than in the non-degraded plots. However, the seed bank may buffer degradation to some extent since the degradation of aboveground vegetation was faster than impoverishment of seed bank. Consequently, seed rain and seed bank of degraded meadows still contained typical mesic meadow species in similar proportions as non-degraded meadows. This indicates that seed rain and seed bank may contribute to the restoration of degraded meadows after the removal of expansive species from the aboveground vegetation.
This paper is the continuation of a survey of the scree vegetation in alpine landscapes of western Pamir-Alai Mts in Tajikistan. In total, 105 phytosociological relevés were collected in the colline and montane belt in 2012‒2014, applying the Braun-Blanquet method. Phytocoenoses inhabiting mobile or fairly stabilised screes of different sizes of rock particles in the montane and colline zone are herein described. A hierarchical syntaxonomic synopsis of scree communities in the western Pamir Alai Mts is provided. The collected vegetation samples represent the majority of the variations among the phytocoenoses of gravel, pebble, cobble and rock block slides and screes. As a result of field survey and numerical analyses, eight associations ‒ Cousinietum corymbosae, Eremostachyetum tadschikistanicae, Cousinietum refractae, Caccinietum dubiae, Eremuretum sogdiani (with two subassociations: E. s. typicum and E. s. delphinietosum decolorati), Feruletum kuhistanicae, Zygophylletum atriplicoidis and Corydalidetum kashgaricae ‒ have been described. Because of their floristic composition, all of these communities have been assigned to a new alliance Alceion nudiflorae within the Sileno brahuicae-Scutellarietalia intermediae order and Artemisio santolinifoliae-Berberidetea sibiricae class. The main factors determining the species composition of the classified associations seem to be scree mobility, rock particle size, elevation above sea level and slope inclination. Saxicolous vegetation in Tajikistan reveal an extraordinary diversity and richness in terms of species composition and beta diversity along the main environmental gradients in this mountaionous areas. A further geobotanical survey is needed, especially in eastern Pamir and adjacent areas to fully recognize the chasmophytic plant communities of this rocky land.
Dry open rocky grassland vegetation on shallow ultramafic soils in the Central Balkans represents typical secondary grasslands, which have developed mainly in the zone of thermophilous mixed deciduous broadleaved and pine forests. Although all relevant national and regional syntaxonomic reviews classify these rocky grasslands within the distinct order Halacsyetalia sendtneri, the syntaxonomic position of the order in different systems of classification has varied in the past. Considering this as well as the fact that there have been no synoptic works on this specific vegetation type, we gathered all available data on the order Halacsyetalia sendtnerii from the serpentinites of the Western and Central Balkan Peninsula for its critical evaluation. The results obtained in our analyses allowed us to propose a new syntaxonomic concept, which is partly in accordance with previously published syntaxonomic schemes. Two alliances can be distinguished: Centaureo kosaninii-Bromion fibrosi and Potentillion visianii, for which the diagnoses, diagnostic and constant taxa are given. Furthermore, we discussed the syntaxonomic position of the order Halacsyetalia sendtneri with respect to the classes Festuco-Brometea and Koelerio-Corynephoretea, as within the analysed associations, many taxa diagnostic for the class Koelerio-Corynephoretea were registered. The thermophytic pioneer grasslands and therophyte sward communities included in the alliance Thymion jankae nomen. inval., characterised by the absence of typical species of the order Halascyetalia sendtneri and presence of taxa diagnostic for the class Koelerio-Corynephoretea, are temporarily left within the order Halacsyetalia sendtneri. Finally, we provided nomenclatural adjustments for the analysed associations when necessary, although a conclusive judgement regarding all the associations currently included within the analysed order can only be made after more detailed field surveys including data on cryptogams as well as joint analyses including all floristically and ecologically similar syntaxa (e.g. Astragalo-Potentilletalia, Festucetalia valesiacae).
Um zu überprüfen, ob sich die Artenzusammensetzung alpiner Kalk-Magerrasen (Blaugras-Horstseggenrasen, Polsterseggenrasen) im Nationalpark Berchtesgaden während der letzten drei Jahrzehnte geändert hat, wurden Vegetationsaufnahmen aus den 1980er Jahren 2013/14 zum zweiten Mal wiederholt vegetationskundlich erfasst.
Ziel der Arbeit war es, durch den Vergleich der Aufnahmenkollektive Vegetationsveränderungen während der letzten drei Jahrzehnte aufzuzeigen und diese als allogene oder autogene Prozesse zu interpretieren. Dabei wurde insbesondere der Frage nachgegangen, ob anthropogene Stickstoff-Einträge als Hauptursache für mögliche Veränderungen angesehen werden können.
Tatsächlich konnten ausgeprägte floristische Veränderungen im Vergleichszeitraum aufgezeigt werden. So hat sich seit den 1980er Jahre die mittlere Artenzahl sowohl im Polsterseggenrasen als auch im Horstseggenrasen um mehr als 10 Arten pro Aufnahmefläche erhöht. Im Polsterseggenrasen wurde ferner eine signifikante Abnahme der mittleren Kontinentalitätszahlen nachgewiesen.
Die dokumentierten floristischen Veränderungen könnten auf die globale Erwärmung und die damit verbundenen Klimaeffekte zurückzuführen sein. Auch natürlich ablaufende Sukzessionsprozesse könnten die aufgezeigten Änderungen in der Artenzusammensetzung erklären, allerdings ist die Zeitspanne von 30 Jahren zu kurz, als dass eine autogene Sukzession als der Hauptfaktor angesehen werden kann. Denkbar ist aber, dass Sukzessionsprozesse durch die globale Erwärmung heutzutage beschleunigt ablaufen. Stickstoffeinträge oder Landnutzungsänderungen spielen als Erklärungsmodell für die Vegetationsveränderungen dagegen wohl eher eine untergeordnete Rolle.
In many regions of Central Europe, semi-natural grasslands have experienced severe vegetation changes, e.g. compositional change and overall species loss, because of land use changes, atmospheric nitrogen input and also climate change. Here we analysed the vegetation change in a dry grassland complex (Gabower Hänge) in the Biosphere Reserve Schorfheide-Chorin (NE Brandenburg, Germany), one of the driest regions of the country. We resampled four 10 m² plots of each of four typical alliances (Festucion valesiacae, Koelerion glaucae, Armerion elongatae, Arrhenatherion elatioris) about 20 years after their original sampling with a recovery accuracy of approx. 10 m. The cover of vascular plants, bryophytes and lichens was recorded in both samplings. The overall compositional change was analysed with a detrended correpondence analysis (DCA). To interpret this change, we calculated unweighted mean Ellenberg indicator values for old and new plots. Furthermore we tested differences in constancy of individual species between old and new plots as well as differences in species richness, cover of herb and cryptogam layer, ecological indicator values and unweighted proportion of species groups (vascular plants, bryophytes, lichens), floristic status (native or not), life forms, CSR-strategy types and Red List species. The results of the ordination indicated no significant vegetation change, but revealed tendencies towards more nutrient-rich conditions. Ellenberg indicator values for nutrients and soil reaction were significantly correlated with the axes of the ordination. There were 28 species exclu-sively found in the new plots and 45 species of the old plots missing. While no species decreased signif-icantly, there were seven species that increased significantly. Mean species richness was significantly increased in the new plots. There were no significant differences in mean Ellenberg indicator values. Proportions of vascular plants, neophytes, hemicryptophytes and CS-strategists decreased. We conclude that overall vegetation changes are small, indicating that the dry grassland complex at the Gabower Hänge is still in a good state and of high conservation value. This relative stability over time compared to the situation in many other dry grasslands throughout temperate Europe is likely attributable to low nitrogen deposition and the dryness of the local climate. However, the detected tendency towards more nutrient-rich conditions should be taken into account in future management.
The majority of studies investigating plant functional traits have used species average trait values, and assumed that average values were sufficiently representative of each species considered. Although this approach has proven valuable in community ecology studies, plant functional traits can significant-ly vary at different scales, i.e. between but also within populations. The study of species functional trait variability can facilitate increasingly accurate studies in community ecology. Nevertheless, the current extent of within-site plant trait variability has been poorly addressed in the literature. Calcareous grass-lands are ecosystems well-suited to study plant trait variation at small spatial scales. Many species are present on heterogeneous calcareous sites, with significant differences in hydric status due to variations in soil depth, soil moisture, aspect, and slope. This study assesses the extent of intra-population func-tional trait variability and tests the hypothesis that this variability can be explained by within-site envi-ronmental heterogeneity. Three functional traits (SLA-specific leaf area, LDMC-leaf dry matter con-tent, and plant vegetative height) were assessed in three populations of four calcareous grassland spe-cies totalling 950 individuals. The heterogeneity in soil depth and potential direct incident radiation was also quantified and related to plant functional trait variability. The intra-population functional trait variability was compared to the inter-population variability of collected data and global inter-population variability data obtained from the worldwide TRY functional traits database. The results showed that SLA, LDMC, and plant height are characterized by considerable intra-population variation (SLA: 72–95%, LDMC: 78–100% and vegetative height: 70–94% of trait variability). The results also indicate higher plant height and larger SLA for individuals located in plots with deeper soils or lower potential direct incident radiation, on gentle slopes or north-facing slopes. Our findings additionally support the concept that higher plant height, higher SLA, and lower LDMC are related to higher availability of soil water. Individuals on shallow soils or in more exposed areas are better equipped to cope with environ-mental stress. Our results indicate plasticity or local adaptation in individuals to environmental hetero-geneity. This study suggests that detailed analyses involving plant functional traits require measure-ments in situ from a large number of individuals, as the degree of individual response strongly depends on an individual’s location and its micro-environmental conditions. Neglecting intra-population trait variability may be critical, as intraspecific variation can be very high at the population scale, and is likely to be driven by local environmental heterogeneity.
