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.
Despite the high significance of the Western Siberian grain belt for crop production in Russia, its weed communities are largely unknown. In this region spring wheat is grown on fertile Chernozem soils with large field sizes but land-use intensity per area is low compared to Central Europe. By using a randomized sampling design we studied arable weed assemblages in the northern forest-steppe zone of Tyumen region on 99 within-field sampling plots of 100 m² size. Surprisingly, with average of 9.8 ± 3.8 species 100 m-2 species richness was low when compared with low-input farming in Central Europe and did not differ between areas of different land-use intensity. Against expectations species composition was not predominantly controlled by soil characteristics and climate, most likely due to short natural gradients. Instead, management factors such as fertilization and tillage intensity seemed to be important factors. Except for two species the Tyumen weed flora consisted mainly of species that are widespread throughout the temperate zone. We found only 10 species with an origin or core area in North Asia or Eastern Europe. The species pool was generally small and with 26% the proportion of non-native species (archaeophytes) was low, when compared to Central European weed communities. Given that weed communities with higher species richness are described from neighboring Bashkiria, we conclude that arable land-use intensity in Tyumen region is high enough to reduce community species richness within arable fields estimated by a randomized sampling design. Since measured soil nutrient values did not affect species richness, herbicide use is most likely the crucial management factor. Furthermore, species-richness was vitally restricted by the small species pool. The low proportion of thermophilous arable weed species that originate from the Mediterranean or Middle-Eastern area and contribute signif-icantly to the Central European weed diversity indicate that climatic dispersal limitations may be re-sponsible for the small number of weed species in the Tyumen flora. An additional constraint was the short history of arable farming in Western Siberia, where considerable arable land use was started only by the end of the 17th century.
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.
The intensification of agricultural practices has led to a severe decrease in grassland biodiversity. Although there is strong evidence that organic farming can reduce the negative impacts of land use, knowledge regarding the most beneficial management system for species richness on organic grasslands is still scarce. This study examines differences in the biodiversity of plants and butterflies on rotationally and continuously grazed pastures as well as on meadows cut twice per year on two large organic suckler cow farms in NE Germany. Vegetation and flower abundance, as factors likely to influence butterfly abundance and diversity, were compared and used to explain the differences. The data attained by vegetation assessments and monthly transect inspections from May to August were analyzed using descriptive statistics and nonparametric methods. The abiotic site conditions of the studied plots had more influence on plant species numbers than the management method. Dry and nutrient-poor areas (mainly poor types of Cynosurion) and undrained wet fens (Calthion) were important for phytodiversity, measured by the absolute number of species, indicator species for ecologically valuable grasslands and the Shannon Index. Meadows tended to have more indicator species than pastures, where small-scale special sites such as wet depressions were crucial for plant diversity. Butterfly diversity was very low, and 90% of the recorded butterflies were individuals of the generalist species Pieris napi. Butterfly abundance depended mainly on occurrence of specific habitat types and specific larval host plants. Supply of flowers was crucial only in certain time periods. Differences in butterfly abundance between the management systems could be explained by the site conditions of the studied grasslands. We conclude that meadows are more favorable to support ecologically valuable plant species; however, their extension is contradictory to the organic farming method of suckler cows maintained outside of stables. Rotationally grazed pastures could be a compromise that would enhance the temporal heterogeneity of flower abundance and vegetation structure. The plant diversity on pastures should be improved by less intensive grazing on special sites and plant species enrichment by means of hay transfer. For enhancing butterfly diversity we suggest to reduce land use intensity especially on poor soils. Considering the economic perspective of the farms, small parts of the agricultural area could be sufficient if connectivity to other suitable habitats is assured. Flower abundance and diversity of larval host plants could be promoted by high diversity of farming practices as well as pre-serving small uncut strips of meadows.