Mesobromion-Flächenzunahme dank Extensivierung im Dübachtal von Rothenfluh (BL) von 1980 bis 2020

Ecological communities always contain a few common species and an abundance of uncommon species. Given that most plant mortality occurs in seeds and seedlings, recruitment success often predicts plant community assemblage and patterning, but observational patterns do not reveal whether plant populations are seed or habitat limited. Grassland plant species make up a sizable portion of the overall native flora in northeastern North America (N.A.), but approximately 30 % of the area’s threatened and endangered flora are grassland species, possibly leftovers from the post-glacial landscape. Yet, close relatives of many rare grassland species thrive in the same range. We investigated whether seed or habitat limitation explained rarity and commonness in remnant grassland species. We used seed addition experiments coupled with microhabitat manipulations (burning and herbivore exclusion) in three different habitat types to evaluate recruitment (germination and seedling survival) limitation for three rare and three common grassland species. Rare grassland species successfully recruited where burning reduced initial competitor density, but seedling survival suggested they were severely limited by interspecific competition. Both the rare and common plant species survived equally well in forest habitats where herbaceous density was low whereas neither survived in the edge habitats. Only the common plants thrived in the high-competition meadow habitat, further suggesting that the rare grassland species are poor competitors. Commonness and rarity are temporal designations that can change as disturbance alters the landscape. Glacial retreat and low precipitation in northeastern N.A. created a landscape suitable for poor competitors that tolerated poor conditions. Our results suggest that rare remnant grassland plants, unlike their close relatives, display more biotic than abiotic limitation as they do not compete well with other plants. These results suggest that suitable habitat is not a spatial location but a temporally transient assemblage of species requirements.

Seed bank composition of open and overgrown calcareous grassland soils—a case study from Southern Belgium

Frequency of plant species in remnants of calcareous grassland and their dispersal and persistence characteristics

Creating novel urban grasslands by reintroducing native species in wasteland vegetation

Contribution of common vs. rare species to species diversity patterns in conservation corridors

Recruitment filtering by a moss layer disadvantages large-seeded grassland species

Lowland calcareous grassland in the UK is a priority habitat designated under the UK Biodiversity Action Plan. Calcareous grasslands used to be common in north-western Europe and were utilized for grazing livestock such as sheep and cows. Many calcareous grasslands in England have been either agriculturally ‘improved’ through the addition of fertilizer and herbicides to increase productivity or have been ploughed up to make way for arable production, which has led to a dramatic decrease in the area of calcareous grassland.Minchinhampton Common is an area of lowland calcareous grassland located within the English county of Gloucestershire. In 1889, a golf course was laid out on the common for the use and enjoyment of local people.The first objective of this project was to investigate whether the presence of the golf course on Minchinhampton Common and associated golf-course management activities have had an effect on the composition and character of the calcareous grassland. The second objective was to investigate whether abandoned golf-course features on Minchinhampton Common, such as old fairways and old greens can recover to resemble undisturbed calcareous grassland.Significant differences were found between the undisturbed calcareous grassland and the fairways, greens and pathways in terms of vegetation height, plant species composition, botanical diversity and soil characteristics. This demonstrates that the presence of the golf course and the management carried out to maintain it has had an effect on the composition and character of the calcareous grassland.Significant differences were found when the fairways and greens were compared with the abandoned old fairways and old greens. This shows that after 15 years of abandonment the old fairways and old greens are no longer similar to the fairways and greens, but they are still different from the undisturbed calcareous grassland. It is hypothesized that to aid recovery, the abandoned features should be cut annually and the clippings removed. This will decrease the nutrient status of the soil and reduce the competitiveness of grasses, thus providing greater opportunities for the establishment of forb species typical of nutrient poor calcareous grasslands in north-western Europe.

Calcareous grasslands have become severely threatened habitats in Europe. The aim of this study was to investigate the changes in plant species richness, and functional and phylogenetic diversity in northern Estonian calcareous (alvar) grasslands resampled after 90 years of land-use change. Functional traits characterizing species that have benefited most from decreased habitat area and altered environmental conditions, and additional species that can potentially inhabit the remaining grassland patches were identified. Also changes in the relative amount of habitat-specific species were studied to detect a possible decrease in habitat integrity. Although grasslands in the studied region had lost most of their original area (~90 %), species richness had substantially increased due to invasion by more competitive, nutrient-demanding native species. Functional diversity generally increased, whereas phylogenetic diversity showed no response to altered conditions. Overall, these grasslands have lost their integrity as calcareous grassland habitat type in the region, because the relative amount of habitat-specific characteristic species has declined significantly. However, although the grasslands have transformed to a ‘hybrid’ habitat type and restoration to their previous state is likely not reasonable, such degraded species-rich grassland fragments can still be recognized as important habitats to preserve high local biodiversity and several characteristic species of calcareous grasslands. As current landscapes consist of an increasing number of hybrid and novel communities, new tools to supplement traditional conservation or restoration practices are necessary to recognize and maintain regions and habitats of high local biodiversity.

Tropical forest vegetation of Xishuangbanna, SW China and its secondary changes, with special reference to some problems in local nature conservation

The abundance of sensitive plant species in calcareous grasslands is threatened by agricultural intensification with nutrient addition and increased livestock densities as well as by land abandonment. The Hill-Shannon diversity is decreasing, and the species composition of Danish calcareous grassland is generally unstable and is expected to experience further change in the coming years. In order to quantify the effects of selected environmental and land-use factors on the observed variation and changes in the vegetation of calcareous grasslands, large-scale spatial and temporal pin-point plant cover monitoring data are fitted in a structural equation model. The analyzed vegetation data come from 100 Danish sites monitored over an eight-year period. The important sources of measurement and sampling uncertainties have been included using a hierarchical model structure. Furthermore, the measurement and sampling uncertainties are separated from the process uncertainty, which is important when generating ecological predictions that may feed into local conservation management decisions. There were significant negative effects of grazing and nitrogen deposition on the change in cover of sensitive plant species. Whereas the negative effect of nitrogen deposition on the cover of sensitive species was expected, it was surprising that the model results suggest that sensitive species may be subjected to overgrazing by the grazing regimes that are currently applied at protected Danish calcareous grasslands. The standardized regression coefficients suggest that the effects of both grazing and nitrogen deposition are relatively benign compared to the effects of soil type, soil pH and precipitation. The relatively large effect of precipitation is interesting, since it is predicted that the amount of precipitation and its distribution over the seasons will change due to climate change, and the results suggest that climate change may lead to important species compositional changes in calcareous grasslands. The fitted model may be used to quantify the uncertainties when generating ecological forecasting and local adaptive management plans. More specifically, this study suggests that it is relevant to rethink the currently used criteria for vegetation height when assessing the conservation status of calcareous grasslands.

Identifying plant and environmental indicators of ancient and recent calcareous grasslands

Restoration of calcareous grasslands: The early successional stage promotes biodiversity

Comparison of mining spoils to determine the best substrate for rehabilitating limestone quarries by favoring native grassland species over invasive plants

Nutrient-poor, dry calcareous grasslands in Central Europe harbour an extraordinary high diversity of plants and invertebrates. Consequently, they are of high conservation value. However, changes in agriculture (intensification or abandonment) have resulted in a dramatic reduction of semi-natural grasslands in the twentieth century. Today, dry grasslands are among the most endangered habitats. Furthermore, these grasslands are frequently fragmented and surrounded by forest or intensively cultivated agricultural areas. Semi-natural grasslands are fragile because their maintenance depends on traditional farming techniques. In order to avoid any loss of species by inappropriate land use, it is important to assess the responses of threatened species to particular types of grassland management. Although different types of present and past pasture management are known to affect the species richness and composition of plant communities, knowledge of the effects on invertebrates is limited. In particular, no studies exist on the influence of different types of pasture management on animals with limited mobility, such as gastropods. In the present thesis, I examined the effects of different pasture management practices on the snail community in dry, nutrient-poor grasslands of the Swiss Jura mountains, where extensive grazing with low stocking rate and without use of fertilizers is a traditional form of grassland management. I assessed the snail communities in extensive pastures grazed by horses, cattle or sheep, in cattle pastures with different management intensity and in extensive pastures with different management history in the last 55 years. Furthermore, gastropod species richness and abundance were examined in transects running from extensive pastures through gradual or abrupt forest edges into the forest interior. Grazing by different livestock species did not affect the species richness, abundance and species composition of land snails. However, independent of livestock species, snail species richness, abundance and number of red-listed species decreased with increasing grazing intensity. Furthermore, cattle pastures without fertilizer application and with low grazing intensity harboured more snail species and more threatened snails than pastures with annual addition of fertilizer and higher grazing intensity. Management intensity had also a negative influence on individual snail species (Cochlicopa lubricella, Truncatellina cylindrica, Vitrina pellucida, Helicella itala and Helix pomatia). Former changes in pasture use for a period of 10–40 years altered the present-day snail fauna. Past shrub cover had a negative effect on the total number of snail species and individuals, the number of open-land species and individuals and the number of red-listed individuals. Former use of fertilizer and higher grazing intensity reduced red-listed species and individuals and altered the snail community. The grassland snail communities of the pastures changed distinctly to forest communities at the first bushes or trees of edges towards forest interior irrespective of the type of forest edge. In pastures, at a distance of 10 m from gradual forest edges, more open-land snail species were found than at the corresponding distance from abrupt forest edges. Furthermore, ecotones of gradual forest edges harboured more open-land individuals than those of abrupt forest edges. For the conservation of grassland land snail communities, it does not matter whether pastures are stocked with horses, cattle or sheep, provided the grazing intensity is low. To preserve the threatened snail species in dry, nutrient-poor grasslands, a network of pastures should be managed without fertilization and grazing intensity should not exceed 180 LU.ha-1.d (product of livestock units per hectare and grazing days). Furthermore, to recover the typical grassland snail community in shrub cleared pastures or former fertilized pastures, the connection between intact pastures and grasslands under restoration should be improved by creating and maintaining new semi-natural areas and by exchanging livestock among these areas during the grazing season. Since shadowing of trees and alterations of the microclimate close to the forest edge may reduce the actual size of small grassland fragments, encroaching shrubs should be regularly removed and gradual forest edges created and maintained.

ABSTRACTBackground: Mechanisms affecting invasiveness of non-indigenous species have received much attention. Few studies have investigated invasions by native plants. Invasive native species such as common ragwort (Jacobaea vulgaris) may become noxious weeds. They challenge farming and nature conservation by outcompeting fodder plants or rare herbs. One mechanism that can result in outcompeting plants is by allelopathy.Aim: We evaluated the potential of J. vulgaris to suppress germination in common and rare grassland species by allelopathy.Methods: In a germination chamber experiment, we exposed 22 species and J. vulgaris itself to ragwort leachate. We controlled for osmotic effects by germination tests in mannitol solution and water. We assessed germination percentage—time —synchrony and radicle length.Results: Leachate reduced germination percentage, germination time, synchrony and radicle length. These effects were similar for J. vulgaris, indicating autotoxicity. Rare species germinated less than common species but were not more sensitive to the phytotoxic effects of J. vulgaris. Restraining effects of the leachate were similar to the mere osmotic effect.Conclusion: Our results question allelopathy as the main driving mechanism behind J. vulgaris gaining dominance. However, the impact of J. vulgaris might depend on the composition of the invaded plant community due to species-specific effects.