- Plant and animal studies
- Ecology and Vegetation Dynamics Studies
- Plant Parasitism and Resistance
- Genetic diversity and population structure
- Botany and Plant Ecology Studies
- Agronomic Practices and Intercropping Systems
- Legume Nitrogen Fixing Symbiosis
- Species Distribution and Climate Change
- Mediterranean and Iberian flora and fauna
- Soil Carbon and Nitrogen Dynamics
- Rangeland and Wildlife Management
- Plant Reproductive Biology
- Peatlands and Wetlands Ecology
- Animal Ecology and Behavior Studies
- Plant Taxonomy and Phylogenetics
- Flowering Plant Growth and Cultivation
- Genetic Mapping and Diversity in Plants and Animals
- Plant responses to elevated CO2
- Genetic and phenotypic traits in livestock
- Geology and Paleoclimatology Research
- Forest Insect Ecology and Management
- Microbial Community Ecology and Physiology
- Insect and Arachnid Ecology and Behavior
- Wildlife Ecology and Conservation
- Insect-Plant Interactions and Control
Philipps University of Marburg
2015-2024
University of Zurich
1997-2016
Musée National d'Histoire Naturelle
2015
University of Basel
1994-1998
University of Florida
1998
Leibniz-Institute for Food Systems Biology at the Technical University of Munich
1998
University of Göttingen
1995
Ruhr University Bochum
1991-1995
Amt für Umwelt
1994
Bangor University
1990
Due to habitat fragmentation many plant species today occur mainly in small and isolated populations. Modeling studies predict that populations will be threatened more strongly by stochastic processes than large populations, but there is little empirical evidence support this prediction for plants. We studied the relationship between size of local (number flowering plants) survival over ten years 359 eight short‐lived, plants northern Germany ( Lepidium campestre , Thlaspi perfoliatum...
Summary Cultivation‐independent techniques were applied to assess the succession and phylogenetic composition of bacterial communities in a vertical oxygen gradient flooded, unplanted paddy soil microcosms. Microsensor measurements showed that within 6 h flooding, was depleted from 200 µM at floodwater‐soil interface undetectable amounts depth approximately 2 mm below. The quite stable over time, although depletion less pronounced 84 days than after flooding. Community fingerprint patterns...
Methanogenesis is traditionally thought to occur only in highly reduced, anoxic environments. Wetland and rice field soils are well known sources for atmospheric methane, while aerated considered sinks. Although methanogens have been detected low numbers some aerated, even desert soils, it remains unclear whether they active under natural oxic conditions, such as biological soil crusts (BSCs) of arid regions. To answer this question we carried out a factorial experiment using microcosms...
Summary 1 We studied reproduction and offspring performance in relation to population size the declining self‐incompatible perennials Primula veris Gentiana lutea . In both species, was strongly reduced small populations, where plants produced fewer seeds per fruit plant. Total seed mass plant higher large but individual were smaller, indicating a trade‐off between number size. Reproduction depressed most populations consisting of less than c. 200 ( P. ) 500 G. ), respectively. 2 The...
We investigated the distribution of genetic variation and relationship between population size in rare plant Gentianella germanica using RAPD (random amplified polymorphic DNA) profiles. Plants for analysis were grown from seeds sampled 72 parent plants 11 G. populations different (40–5000 fruiting individuals). In large populations, parents two spatially distinct subpopulations comparable area to total covered by small populations. Analysis molecular variance revealed significant among ( P...
1 We studied the relationships between population size, reproduction and growth rate in 23 populations of rare, short‐lived plant Gentianella germanica . also investigated a possible correlation size effects with environmental variation climate, topography, soil, vegetation, management. To ascertain whether differences have genetic basis, we grew 20 seed families from each common garden experiment. 2 In 1993, sizes ranged 40 to 5000 flowering plants field (geometric mean 386). Plants small...
Isolation and small size of populations as a result habitat destruction fragmentation may negatively affect plant fitness through pollinator limitation increased levels inbreeding. To increase genetic variation in rare plants artificial gene flow has been suggested management tool. We investigated whether inbreeding depression could reduce Gentianella germanica, an endangered biennial increasingly fragmented calcareous grasslands Central Europe. experimentally excluded pollinators generated...
We studied the influence of eight nonleguminous grassland plant species belonging to two functional groups (grasses and forbs) on composition soil denitrifier communities in experimental microcosms over consecutive years. Denitrifier community was analyzed by terminal restriction fragment length polymorphism (T-RFLP) PCR-amplified nirK gene fragments coding for copper-containing nitrite reductase. The impact factors (plant group, species, sampling time, interactions between them) structure...
Abstract Competition simultaneously limits the availability of above‐ and below‐ground resources for plants. How plants respond to density with changes in patterns biomass allocation is poorly understood. Previous studies had inconsistent results, but emphasised increased stems response density. However, may depend on environmental conditions characteristics species. We grew 43 herbaceous plant species at three densities (1, 8 64 individuals per pot) two nutrient levels a common garden...
Summary 1 We studied the relationship between diversity of grassland communities and effects generalist hemiparasitic plant Rhinanthus alectorolophus. compared resistance against biomass loss as a consequence infection, performance parasite parasitized to invasion by other species. Seeds were sown into experimental plots containing 1, 2, 4, 8 or 32 species belonging one more three functional groups (grasses, legumes non‐leguminous herbs). 2 predicted that infection will reduce host biomass,...
1 Host plants are for hemiparasites both their main source of water and nutrients potential competitors light. To investigate the balance between costs benefits host presence a greenhouse experiment was performed with two facultative root Rhinanthus serotinus Odontites rubra Medicago sativa. Above-ground (light competition) below-ground (parasitic) interactions were separated killed 4, 8 12 weeks after planting by cutting off shoots. 2 R. remained smaller than 0. when grown autotrophically...
Summary Many rare plant species are restricted to small isolated populations in which fitness may be reduced because of inbreeding, environmental and demographic stochasticity, pollination. However, specialist herbivores less likely present such higher probabilities herbivore extinction lower rates colonization, therefore affect only larger populations. We studied the relationships between size endangered grassland Gentiana cruciata probability occurrence population its herbivore, butterfly...
Root hemiparasitic plants frequently establish haustorial connections simultaneously to several host species, which may differ in the quality of their contribution nutrition parasite and sensitivity parasitic attack. The obligate hemiparasite Melampyrum arvense was grown with three species (Lolium perenne, Medicago sativa Linum usitatissimum) all possible binary mixtures test whether (1) a mixed supply (e.g. legume grass) results an increase heterotrophic benefit (2) influence competitive...
Traditionally managed mountain grasslands in the Alps are species‐rich ecosystems that developed during centuries of livestock grazing. However, changes land use including fertilisation well accessible pastures and gradual abandonment remote sites increasingly threatening this diversity. In five regions Swiss French we assessed relationship between use, soil resource availability, cover unpalatable species Veratrum album, richness vegetation composition across four spatial scales ranging...
We studied the effects of population size on interactions between Scorzonera humilis (Asteraceae), its specialised seed‐feeding fly Heterostylodes macrurus (Anthomyidae) and specific systemic smut fungus Ustilago scorzonerae (Ustilaginales). The number seeds developing per plant (potential seed production) strongly increased with in S. humilis. However, because predation by feeding H. negative impact pathogen U. also increased, realised production was not related to size. probability...
Summary Habitat deterioration has resulted in the extinction of many local populations plants. However, long‐lived plants there may be a time lag between habitat and decline population size, although some vital rates immediately affected. We studied dynamics viability endangered, perennial Scorzonera humilis to different levels agricultural intensification five over period 4 years at genet level for 3 rosette (ramet) level. Asymptotic growth varied little observed stage structure was very...
Changes in land-use have resulted the decline of many formerly common plants nutrient-poor grasslands Europe. Recently, extensification schemes been applied at sites order to restore former habitat conditions. However, establishment rare and endangered is often severely limited by lack propagules both seed bank surrounding landscape. For such species deliberate introductions may be necessary overcome these limitations. In a 7-year study, we assessed importance gaps created sod cutting, plant...
To explore potential links between plant communities, soil denitrifiers and denitrifier function, the impact of presence, diversity (i.e. species richness) combination on nirK-type community composition activity was studied in artificial grassland assemblages over two consecutive years. Mesocosms containing zero, four eight different combinations were set up. Differences analysed by canonical correspondence analyses following terminal restriction fragment length polymorphism analysis...
Abstract. Natural sceneries or single plants may have positive influences on human health. Here we show that plant species richness can positively influence recovery from stress. Meadow-like arrays of different (1, 16, 32, 64 species) were presented to visitors (n=171) a popular park in Zurich, Switzerland (one array per participant). Participants' systolic blood pressure was measured twice: directly after they had been stressed and once again 2 min post-stress relaxation period during which...
Abstract Mutualistic interactions are by definition beneficial for each contributing partner. However, it is insufficiently understood how mutualistic influence partners throughout their lives. Here, we used animal species-explicit, microhabitat-structured integral projection models to quantify the effect of seed dispersal 20 species on full life cycle tree Frangula alnus in Białowieża Forest, Eastern Poland. Our analysis showed that increased population growth 2.5%. The effectiveness...