Northern Swiss Jura Mountains Research Articles

Spatial capture-recapture with multiple noninvasive marks: An application to camera-trapping data of the European wildcat (Felis silvestris) using R package multimark.

In Switzerland, the European wildcat (Felis silvestris), a native felid, is protected by national law. In recent decades, the wildcat has slowly returned to much of its original range and may have even expanded into new areas that were not known to be occupied before. For the implementation of efficient conservation actions, reliable information about the status and trend of population size and density is crucial. But so far, only one reliable estimate of density in Switzerland was produced in the northern Swiss Jura Mountains. Wildcats are relatively rare and elusive, but camera trapping has proven to be an effective method for monitoring felids. We developed and tested a monitoring protocol using camera trapping in the northern Jura Mountains (cantons of Bern and Jura) in an area of 100 km2. During 60 days, we obtained 105 pictures of phenotypical wildcats of which 98 were suitable for individual identification. We identified 13 individuals from both sides and, additionally, 5 single right‐sided flanks and 3 single left‐sided flanks that could not be matched to unique individuals. We analyzed the camera‐trap data using the R package multimark, which has been extended to include a novel spatial capture–recapture model for encounter histories that include multiple “noninvasive” marks, such as bilaterally asymmetrical left‐ and right‐sided flanks, that can be difficult (or impossible) to reliably match to individuals. Here, we present this model in detail for the first time. Based on a “semi‐complete” data likelihood, the model is less computationally demanding than Bayesian alternatives that rely on a data‐augmented complete data likelihood. The spatially explicit capture–recapture model estimated a wildcat density (95% credible interval) of 26 (17–36) per 100 km2 suitable habitat. Our integrated model produced higher abundance and density estimates with improved precision compared to single‐sided analyses, suggesting spatially explicit capture–recapture methods with multiple “noninvasive” marks can improve our ability to monitor wildcat population status.

Intensity-dependent impact of sport climbing on vascular plants and land snails on limestone cliffs

Limestone cliffs in the Jura Mountains harbour species-rich plant and animal communities including rare species. Sport climbing has recently increased in popularity in this habitat and several studies have reported damage to cliff biodiversity. However, so far how damage levels vary with climbing intensity has not been investigated. We evaluated the effects of climbing intensity on the diversity of vascular plants and land snails in 35 limestone cliff sectors in the Northern Swiss Jura Mountains. Mixed-effects models were used to examine whether species richness of plants and land snails differ between cliff sectors with low and high climbing intensity and unclimbed cliff sectors (controls) taking into account potential influences of cliff characteristics (aspect, cliff height, rock microtopography). At the cliff base, the best fit model revealed that plant species richness was affected by climbing intensity and cliff aspect. Plant species richness was reduced by 12.2% and 13.1%, respectively, in cliff sectors with low and high climbing intensity compared to unclimbed cliff sectors. On the cliff face, plant species richness was only influenced by climbing intensity (species richness reduction by 24.3% and 28.1%). Combining data from cliff base, face and plateau, the best fit model revealed that land snail species richness was only affected by climbing intensity (species richness reduction by 2.0% and 13.7%). In both organism groups, species composition was increasingly altered by increasing climbing intensity. Our study provides evidence that even low climbing intensity reduces cliff biodiversity and that damage becomes more pronounced with increasing climbing intensity.

Impact assessment of intense sport climbing on limestone cliffs: Response of rock-dwelling land snails

Exposed limestone cliffs in the Swiss Jura Mountains harbour a diverse gastropod community with some rare species. Sport climbing has recently increased in popularity on these cliffs. We examined the effects of sport climbing and microtopographical features of rock faces on terrestrial gastropods by assessing species diversity and abundance on climbing routes and in unclimbed areas of seven isolated cliffs in the Northern Swiss Jura Mountains. We considered exclusively living individuals resting attached to rock faces. In total, 19 gastropod species were recorded. Six of them were specialized rock-dwelling species, whose individuals spend their entire life on rock faces, feeding on algae and lichens. Plots along climbing routes harboured fewer species of rock-dwelling snails as well as other gastropod species (usually living in the leaf litter layer at the cliffs’ base) than plots in unclimbed control areas. Similarly, both the density of individuals and frequency of occurrence in plots were reduced in both groups of snails on climbing routes. The complexity of the rock surface had little influence on the species richness and abundance of gastropods. Pyramidula pusilla, the species with the smallest shell and a preference to rest underneath overhangs, was less affected by sport climbing than snail species with larger shells and a preference to rest on exposed smooth rock surface. Our findings indicate land snail diversity and abundance are suitable indicators for impact assessment in rocky habitats. Future management plans and actions should therefore not only rely on plants; they ought to consider also gastropods and other invertebrates. Any management plan should include a comprehensive information campaign to show the potential impact of intensive sport climbing on the specialized flora and fauna with the aim of educating the climbers and increasing their compliance with such measures.

Reinhart A. Gygi (1935–2014): Scientific achievements of a life-long commitment to research in Late Jurassic carbonate sedimentology and biostratigraphy of the northern Swiss Jura Mountains

On November 7th 2014, Reinhart A. Gygi died in his home at the Carl-Spitteler-Strasse 70 in Zurich-Witikon. With him, the scientific community lost the foremost expert of Late Jurassic stratigraphy of the Swiss Jura Mountains, and of Late Jurassic ammonites. During 34 years, he worked as curator at the Natural History Museum Basel, and he was a long-term member of the Swiss Palaeontological Society and the Swiss Geological Society. Reinhart A. Gygi, citizen of Aarau AG and Kappelen BE, was born in Zurich on November 25th 1935. His father was the engineer Hans Adolf Gygi who would later become director of the Holderbank Cement Mills and himself son of the factory founder Adolf Gygi. His mother was Berta Marilies, born Reinhart. Reinhart spent his early years together with his three siblings in the parental home in Moriken-Wildegg. He attended the primary school in Moriken, secondary and high school in Aarau. An inspiring high-school teacher was responsible that Reinhart became enthusiastic about geology. From 1954 on he stayed in Aarau, first in the house of family friends, then in his aunt Clarli’s house. Reinhart finished high school and passed the final exam in March 1956. In the following summer, Reinhart accompanied his father on a business trip to Canada. There he could work as trainee in a mining company and experienced the hard life of a prospecting geologists searching for iron and nickel ores. In October 1956, Reinhart started to study geology in Zurich, until summer 1957 at the ETH, then at the University of Zurich. During his early study years he already acted as an advisor for civil engineering and highway constructions. In 1961 he had completed the mandatory geological mapping, which he did in his ‘‘home range’’ on the Chestenberg just north of Moriken-Wildegg. This resulted in his first two publications (Hofmann and Gygi 1961; Gygi and Trumpy 1966). In 1962, Reinhart started working on his PhD thesis. Professor Rudolf Trumpy had proposed to investigate the Upper Jurassic of the canton Aargau, a subject that initially did not promise to be very rewarding to the student, but fieldwork, which was soon extended to the cantons Solothurn and Schaffhausen, yielded very interesting results. Reinhart had by that time already established himself as an expert of Jurassic stratigraphy of the Jura Mountains (Gygi and Stumm 1965; Gygi 1966a; Gygi et al. 1966). First results of his PhD work were published in 1966 (Gygi 1966b), and Reinhart finished his thesis on the Oxfordian of northern Switzerland and was promoted in the autumn of 1967. Reinhart had planned to become prospecting geologist, but Rudolf Trumpy could persuade him to apply for a research job. On December 1st 1967, he started working as research assistant at the Natural History Museum Basel where he could pursue his studies on the Upper Jurassic of northern Switzerland. The first month of the employment he worked without salary that he compensated with a month of travel abroad in April 1968. From his parents, Reinhart had received a 4WD-truck, a Volvo Laplander, as a present for passing the promotion, and he undertook together with a colleague a longer trip to the Middle East with this vehicle in April 1968. The focus of this trip was rather cultural than geological. Later this truck would also accompany him for fieldwork in many quarries of northern Switzerland. Another stay abroad during his first year at the Natural History Museum of Basel took him in the summer 1968 to Bermuda where he & Walter Etter walter.etter@bs.ch

Population structure and genetic diversity of relict populations of Alyssum montanum on limestone cliffs in the Northern Swiss Jura mountains

Exposed cliffs in the Northern Swiss Jura mountains harbour a highly diverse flora with numerous rare and relict plant species. The genetic structure of cliff populations is of particular interest because in a variety of plant species the populations are small, isolated and separated from their main distribution area in the Alps and the Mediterranean. We examined possible relationships between population size and size structure, sexual reproduction and genetic diversity of Alyssum montanum, a relict plant species occurring on limestone cliffs in the Northern Swiss Jura mountains. The population size of A. montanum ranged from 8 to 248 plant individuals on the 12 cliffs examined. Most populations contained a high proportion of small-sized (=young) plants indicating a successful establishment of seedlings. Fitness-related traits of A. montanum (percentage of reproductive individuals, number of fruits, fruit weight) varied widely between cliffs and were neither related to the size of the populations nor to the percentage of vegetation cover on the cliffs. RAPD-PCR analysis revealed that A. montanum populations exhibit a remarkably high genetic diversity. However, genetic diversity decreased with decreasing population size. Moreover, the positive relationship found between genetic variability and fitness-related traits indicates that population size is a key factor for the persistence of A. montanum on limestone cliffs.

Delayed response in a plant–pollinator system to experimental grassland fragmentation

The fragmentation of natural habitat is considered to be a major threat to biodiversity. Decreasing habitat quality and quantity caused by fragmentation may lead to a disruption of plant-pollinator interactions and to a reduction in sexual reproduction in plant species. We conducted a 6-year field experiment to investigate the effects of small-scale fragmentation on plant-pollinator interactions and genetic diversity in the self-compatible Betonica officinalis. We examined the abundance and composition of pollinators, the foraging behaviour of bumblebees and the performance, outcrossing rate and genetic diversity of B. officinalis after 2 and 6 years in experimentally fragmented nutrient-poor, calcareous grassland in the northern Swiss Jura mountains. Fragments of different size (2.25 and 20.25 m(2)) were isolated by a 5-m-wide strip of frequently mown vegetation. Control plots of corresponding size were situated in adjacent undisturbed grassland. Experimental grassland fragmentation altered the composition of B. officinalis pollinators and reduced their flower visitation rate. Furthermore, the foraging behaviour of bumblebees was changed in the fragments. After 6 years of fragmentation seed weight was higher in fragments than in control plots. However, the densities of B. officinalis rosettes and inflorescences, plant height and inflorescence length were not affected by fragmentation. The outcrossing frequency of B. officinalis growing in fragments was reduced by 15% after 2 years and by 33% after 6 years of experimental fragmentation. This resulted in a significant reduction of the genetic diversity in seedlings emerging in fragments after 6 years. Our study shows that small-scale habitat fragmentation can disturb the interaction between B. officinalis and pollinators resulting in a reduced outcrossing frequency and genetic diversity in plants growing in fragments. However, the response to fragmentation was considerably delayed. This finding strengthens the claim for long-term field experiments with proper replications and controls to assess delayed effects of habitat fragmentation.

Population dynamics of six land snail species in experimentally fragmented grassland

1. The fragmentation of natural habitats is generally considered to be a major threat to biodiversity. Different species may respond differently to habitat fragmentation, depending on species-specific traits such as body size, dispersal ability, mating system, and habitat requirement. 2. The population sizes, extinction and recolonization frequencies of six naturally occurring land snail species (Cochlicopa lubrica, Vertigo pygmaea, Pupilla muscorum, Punctum pygmaeum, Helicella itala, and Trichia plebeia) were examined over 3 years in an experimentally fragmented nutrient-poor, calcareous grassland in the northern Swiss Jura mountains using a mark-recapture technique. Fragments of different size (0.25 m(2), 2.25 m(2), and 20.25 m(2)) were isolated by a 5-m wide strip of frequently mown vegetation. Control plots of corresponding size were situated in adjacent undisturbed grassland. 3. Experimental grassland fragmentation influenced the population size in all snail species except H. itala, which is the species with the biggest shell and it is also active under mild conditions in winter. However, fragmentation affected different species to a different extent. 4. Extinction (= disappearance from a plot) frequency increased with time, decreasing population size and decreasing plot size in all species. Large populations had a lower extinction probability than small populations. Fragmentation increased the probability of extinction, which also differed among snail species. The effect of plot size on extinction probability was still significant even after the effect of population size had been taken into account. 5. Fragments and control plots did not differ in recolonization frequencies when all six species were considered. However, fragmentation influenced recolonization frequency when the two species with large shells (H. itala and T. plebeia) were excluded from the analysis. 6. Our study shows that small-scale grassland fragmentation affects different land snail species to a different extent. This finding strengthens the claim for multi-species approaches to obtain general predictions of fragmentation impact.

Effect of rock climbing on the calcicolous lichen community of limestone cliffs in the northern Swiss Jura Mountains

Exposed limestone cliffs in the Swiss Jura Mountains harbour a diverse lichen community with some rare species. Sport climbing has recently increased in popularity on these cliffs. We examined the effect of sport climbing on calcicolous lichens by assessing species diversity and cover of lichens in climbed and unclimbed areas of 10 isolated cliffs in the northern Swiss Jura Mountains. We also investigated possible associations between lichens and lichen-feeding land snails on these cliffs. A total of 38 calcicolous lichen species, three bryophytes and one alga were found on the rock faces of 10 cliffs. Twenty lichen species (52.6%) were epilithic, 16(42.1%) endolithic and two (5.3%) foliose. Overall, the epilithic lichen species covered 8.3% of the rock surface, endolithic species 10.2%, and foliose species 0.03%. Climbed and unclimbed rock areas did not differ in total number of lichen species, species density (number of species per 100 cm(2)) or total lichen cover. However, the frequency of occurrence of epilithic lichens was lower along climbing routes than in unclimbed areas. A multi-response permutation test showed that the lichen community composition of climbed areas differed from that of unclimbed areas. The dissimilarity of lichen communities between climbed and unclimbed areas increased with increasing climbing intensity on the focal route in climbed areas, but not with the age of the climbing route. Five of the 11 snail species recorded on the cliff faces were specialized lichen feeders. Plots along climbing routes harboured fewer snail species than plots in unclimbed areas. Total snail abundance was positively correlated with lichen species richness, but no correlation between snail species richness and lichen species richness was found. Our results indicate that frequent rock climbing can change the lichen community and reduce the snail community of limestone cliffs. A climbing-related reduction of snail abundance may also alter the lichen-herbivore interaction and indirectly change competitive interactions among lichen species. (Less)

Effects of forestry practices on relict plant species on limestone cliffs in the northern Swiss Jura mountains

Limestone cliffs in the forests of the Swiss Jura mountains harbour a highly diverse plant community including glacial relict species. This unique cliff vegetation is increasingly threatened by overgrowing forest and recreational activities (sport climbing and picnicking). Management objectives of the surrounding forest focus on the conservation of the cliff vegetation. The most suitable forestry practice to achieve this goal is, however, still unknown. We examined the effects of two different forestry practices (clear-cutting and shelter tree cutting) on the species richness and abundance of vascular plants on the face, at the base and on the talus of three cliffs. As controls we considered areas with no management in the past 80 years (forest reserves) at the same cliffs. Plant species density (number of species/m 2) and vegetation cover were higher in shelter cut areas than in the forest reserves both on the talus and at the cliff base. Clear-cut areas had a higher vegetation cover than forest reserves on the talus. Shelter cut areas showed a larger proportion of plants with high light demand and a higher mean light score of plants than clear-cut areas and forest reserves. We conclude that selective cutting of trees (shelter tree cutting) is the best forestry practice for the conservation of a high biodiversity and a multitude of relict plant species on limestone cliffs in the Jura mountains. However, this forestry practice is time-consuming and thus expensive. To preserve the specialised cliff flora, sponsorship for this forestry practice is needed from governmental and non-governmental organisations.

Experimental habitat fragmentation and invertebrate grazing in a herbaceous grassland species

A field experiment was conducted to examine the effects of habitat fragmentation on herbivore damage to individually tagged leaves of Betonica officinalis rosettes. Fragments of different size and corresponding control plots were established at three study sites in nutrient-poor calcareous grasslands in the northern Swiss Jura mountains. Leaf damage was recorded three times over the growing season (late spring, summer and early autumn). Five years after the initiation of the fragmentation, the density of rosettes did not differ between fragments and control plots. The number of leaves per rosette was higher in fragments than in control plots in summer but not in late spring and early autumn. The extent of leaf damage, expressed as proportion of leaf area removed by invertebrate herbivores, increased over the vegetation period. Leaf damage was greater in fragments than in control plots at two study sites, whereas the opposite (less strongly expressed) was found at the third site. Number of species and density (individuals per m(2)) of potential herbivores (gastropods and grasshoppers) were recorded in all. fragments and control plots. Effects of fragmentation on the number of species and densities depended on plot size and differed between gastropods and grasshoppers. Leaf damage in fragments increased with increasing density of gastropods if the third site, which had lowest leaf damage, was excluded. Such a positive relationship was neither found in control plots nor for grasshopper densities. Thus, movement of gastropods in fragments was probably restricted which resulted in increased feeding pressure at least in two sites. However, even if our fragmentation experiment was well designed and replicated, the interpretation of these experimental results remains difficutt because there was large site-to-site and seasonal variation. (c) 2005 Gesellschaft fur bkologie. Published by Elsevier GmbH. All rights reserved.

Effects of experimental small-scale habitat fragmentation on above- and below-ground plant biomass in calcareous grasslands

The effect of small-scale fragmentation on the above-ground plant biomass was examined in nutrient-poor calcareous grasslands in the northern Swiss Jura mountains in three successive years. In the same field experiment, the fragmentation effect on the below-ground plant biomass was evaluated in 1 year. Additionally, species richness and abundance of plants were recorded. The experimental set-up consisted of 12 blocks with 48 fragments (24 small, 12 medium and 12 large) and 48 corresponding control plots distributed over three study sites. Fragmentation was maintained by frequently mowing the area between the fragments. Three to 5 years after the beginning of the experiment, plant biomass was harvested in all fragments and control plots in late autumn every year. In general, fragments contained more above- and below-ground plant biomass than control plots. The increase in above-ground plant biomass was partly due to an increased density of plants, and partly due to a change in species composition in fragments. In particular, a competitive shift of dominance towards tall grasses and forbs at the expense of smaller forbs was observed. Beside the main fragmentation effect on above-ground plant biomass, interactive effects with year of investigation, study site and plot size were found. This indicates that the observed fragmentation effect is a combined result of various factors acting to a different extent at different sites and plot sizes. The fragmentation-related increase in plant productivity could affect higher trophic levels such as herbivore and predator communities.

Rock climbing alters the vegetation of limestone cliffs in the northern Swiss Jura Mountains

Exposed cliffs in the northern Swiss Jura Mountains harbour a highly diverse flora with numerous endangered and relic plant species. On these cliffs, sport climbing is enjoying increasing popularity. We examined the ecological effects of sport climbing on vascular plants at the cliff base and on the cliff face by assessing plant cover and species density at various distances from frequently used climbing routes. Plant cover was significantly reduced at the base of climbing routes. Furthermore, species density (number of species per square metre) at the cliff base, as well as plant cover and species density at the cliff face, tended to increase with distance from the route. We also compared the vegetation of five frequently climbed cliffs with that of seven unclimbed cliffs. Climbing significantly altered the plant composition. Specialized rock species occurred less frequently on climbed cliffs than on unclimbed cliffs. Management plans and conservation actions are needed to preserve the threatened plant species on frequently climbed cliffs. Such plans should include the establishment of climbing-free protection areas on cliffs with a high number of specialized, relic plants and the protection of entire cliffs that are not yet climbed.Key words: disturbance, vegetation, Jura Mountains, rock climbing, limestone cliff.

Effects of experimental small‐scale grassland fragmentation on spatial distribution, density, and persistence of ant nests

Abstract. 1. Grassland fragmentation is expected to influence the abundance of different invertebrate species to a different extent. Fragmentation‐related effects are of particular importance in species that interact with many other species.2. The density and spatial distribution of nests of 15 ant species in experimentally fragmented calcareous grasslands at three sites in the Northern Swiss Jura mountains were examined. Fragments of different size (0.25 m2, 2.25 m2, and 20.25 m2) were isolated by a 5‐m wide strip of frequently mown vegetation. Control plots of corresponding size were situated in adjacent undisturbed grassland.3. Three years after initiation of the experiment, ant nest density did not differ between fragments and control plots. Six years after initiation of the experiment, however, ant nest density and forager abundance were higher in large fragments than in large control plots. Ant nests tended to occur more frequently along the edge of fragments than in the core area. Persistence time of nests of the most abundant species, Lasius paralienus, tended to be shorter in fragments than in control plots. Furthermore, persistence time was longer in nests situated close to the fragment edge than in nests in the core area.4. Effects on nest density, edge effects on the spatial distribution of nests, and the relationships between nest density and environmental factors were more pronounced when only nests of L. paralienus were considered. The implications of these findings for plant and other invertebrate species are discussed.

Overgrowing forest as a possible cause for the local extinction of Vipera aspis in the northern Swiss Jura mountains

Overgrowing forest as a possible cause for the local extinction of Vipera aspis in the northern Swiss Jura mountains

Overgrowing forest as a possible cause for the local extinction of Vipera aspis in the northern Swiss Jura mountains

Abstract In the northern Swiss Jura mountains, the Asp viper Vipera aspis was common until the 1940ies. During the past 50 years many local populations went extinct and nowadays the species is considered as threatened. We compared habitat characteristics of localities with extant viper populations with those of localities where the species became extinct. These two groups of localities did not differ in exposure, altitude, inclination, soil structure and cover of ground vegetation. However, localities where the species is still found were situated more frequently at forest edges, in dry meadows and at roadsides, whereas localities in which V. aspis became extinct were situated more frequently in forests. Tree density was lower at localities where the viper is still present. The results suggest that former habitats of V. aspis became overgrown by bushes and trees, which in turn may have led to a colder, more humid and thus unfavourable microclimate for V. aspis. We conclude that logging is an essential tool to maintain suitable habitat for this thermophilous ovoviviparous reptile.

Ooidal ironstones and ferruginous microbialites: origin and relation to sequence stratigraphy (Aalenian and Bajocian, Swiss Jura mountains)

ABSTRACTAalenian and lower Bajocian rocks in the central and northern Swiss Jura mountains comprise a series of parasequences that mainly reflect a shallowing‐upward trend in a shallow, mixed carbonate/siliciclastic depositional environment. Within a parasequence, ooidal ironstones may occur at three specific types of horizons. These are: regressional discontinuities and transgressional discontinuities formed by sediment bypassing, and omissional discontinuities formed by starvation.Ooidal ironstones, which principally are autochthonous, accumulated during both sea‐level rises and falls in a relatively broad bathymetric and hydrodynamic spectrum. The key physical factor for ferruginous ooid genesis is non‐deposition.Ferruginous ooids and microbialites consist of goethite, chamosite and mixtures thereof, with subordinate amounts of apatite and silica. Ferruginous ooids grew stepwise on the sediment surface in an oxygenated marine environment. Ferruginous microbialites, being the product of benthic microbial communities, grew − partly in cavities − in aerated moderate‐ to high‐energy environments. Thus, chamosite evolved from a precursor substance stable under oxidizing conditions.The close mineralogical and micromorphological resemblance of ferruginous microbialites and ooids suggests a common biogenic origin. Structural rearrangement of a biologically accreted gel‐like precursor substance consisting of various amorphous hydroxides is considered a probable mode of mineral genesis in both ferruginous ooids and microbialites.