Refine
Year of publication
Document Type
- Article (105)
- Postprint (5)
- Part of Periodical (1)
Is part of the Bibliography
- yes (111)
Keywords
- land use (6)
- Biodiversity exploratories (5)
- fertilization (5)
- Biodiversity Exploratories (4)
- Nitrogen (4)
- biodiversity (4)
- biodiversity exploratories (4)
- Auger electron spectroscopy (3)
- Forest management (3)
- Phosphorus (3)
Institute
- Institut für Biochemie und Biologie (93)
- Institut für Physik und Astronomie (5)
- Institut für Chemie (3)
- Hasso-Plattner-Institut für Digital Engineering GmbH (2)
- Institut für Ernährungswissenschaft (2)
- Department Psychologie (1)
- Humanwissenschaftliche Fakultät (1)
- Institut für Geowissenschaften (1)
- Mathematisch-Naturwissenschaftliche Fakultät (1)
- Vereinigung für Jüdische Studien e. V. (1)
Although temporal heterogeneity is a well-accepted driver of biodiversity, effects of interannual variation in land-use intensity (LUI) have not been addressed yet. Additionally, responses to land use can differ greatly among different organisms; therefore, overall effects of land-use on total local biodiversity are hardly known. To test for effects of LUI (quantified as the combined intensity of fertilization, grazing, and mowing) and interannual variation in LUI (SD in LUI across time), we introduce a unique measure of whole-ecosystem biodiversity, multidiversity. This synthesizes individual diversity measures across up to 49 taxonomic groups of plants, animals, fungi, and bacteria from 150 grasslands. Multidiversity declined with increasing LUI among grasslands, particularly for rarer species and aboveground organisms, whereas common species and belowground groups were less sensitive. However, a high level of interannual variation in LUI increased overall multidiversity at low LUI and was even more beneficial for rarer species because it slowed the rate at which the multidiversity of rare species declined with increasing LUI. In more intensively managed grasslands, the diversity of rarer species was, on average, 18% of the maximum diversity across all grasslands when LUI was static over time but increased to 31% of the maximum when LUI changed maximally over time. In addition to decreasing overall LUI, we suggest varying LUI across years as a complementary strategy to promote biodiversity conservation.
Bottom-up effects of plant diversity on multitrophic interactions in a biodiversity experiment
(2010)
1. For managed temperate forests, conservationists and policymakers favour fine-grained uneven-aged (UEA) management over more traditional coarse-grained even-aged (EA) management, based on the assumption that within-stand habitat heterogeneity enhances biodiversity. There is, however, little empirical evidence to support this assumption. We investigated for the first time how differently grained forest management systems affect the biodiversity of multiple above- and below-ground taxa across spatial scales. 2. We sampled 15 taxa of animals, plants, fungi and bacteria within the largest contiguous beech forest landscape of Germany and classified them into functional groups. Selected forest stands have been managed for more than a century at different spatial grains. The EA (coarse-grained management) and UEA (fine-grained) forests are comparable in spatial arrangement, climate and soil conditions. These were compared to forests of a nearby national park that have been unmanaged for at least 20years. We used diversity accumulation curves to compare -diversity for Hill numbers D-0 (species richness), D-1 (Shannon diversity) and D-2 (Simpson diversity) between the management systems. Beta diversity was quantified as multiple-site dissimilarity. 3. Gamma diversity was higher in EA than in UEA forests for at least one of the three Hill numbers for six taxa (up to 77%), while eight showed no difference. Only bacteria showed the opposite pattern. Higher -diversity in EA forests was also found for forest specialists and saproxylic beetles. 4. Between-stand -diversity was higher in EA than in UEA forests for one-third (all species) and half (forest specialists) of all taxa, driven by environmental heterogeneity between age-classes, while -diversity showed no directional response across taxa or for forest specialists. 5. Synthesis and applications. Comparing EA and uneven-aged forest management in Central European beech forests, our results show that a mosaic of different age-classes is more important for regional biodiversity than high within-stand heterogeneity. We suggest reconsidering the current trend of replacing even-aged management in temperate forests. Instead, the variability of stages and stand structures should be increased to promote landscape-scale biodiversity.
In order to predict which ecosystem functions are most at risk from biodiversity loss, meta-analyses have generalised results from biodiversity experiments over different sites and ecosystem types. In contrast, comparing the strength of biodiversity effects across a large number of ecosystem processes measured in a single experiment permits more direct comparisons. Here, we present an analysis of 418 separate measures of 38 ecosystem processes. Overall, 45 % of processes were significantly affected by plant species richness, suggesting that, while diversity affects a large number of processes not all respond to biodiversity. We therefore compared the strength of plant diversity effects between different categories of ecosystem processes, grouping processes according to the year of measurement, their biogeochemical cycle, trophic level and compartment (above- or belowground) and according to whether they were measures of biodiversity or other ecosystem processes, biotic or abiotic and static or dynamic. Overall, and for several individual processes, we found that biodiversity effects became stronger over time. Measures of the carbon cycle were also affected more strongly by plant species richness than were the measures associated with the nitrogen cycle. Further, we found greater plant species richness effects on measures of biodiversity than on other processes. The differential effects of plant diversity on the various types of ecosystem processes indicate that future research and political effort should shift from a general debate about whether biodiversity loss impairs ecosystem functions to focussing on the specific functions of interest and ways to preserve them individually or in combination.
Organic management is one of the most popular strategies to reduce negative environmental impacts of intensive agriculture. However, little is known about benefits for biodiversity and potential worsening of yield under organic grasslands management across different grassland types, i.e. meadow, pasture and mown pasture. Therefore, we studied the diversity of vascular plants and foliage-living arthropods (Coleoptera, Araneae, Heteroptera, Auchenorrhyncha), yield, fodder quality, soil phosphorus concentrations and land-use intensity of organic and conventional grasslands across three study regions in Germany. Furthermore, all variables were related to the time since conversion to organic management in order to assess temporal developments reaching up to 18 years. Arthropod diversity was significantly higher under organic than conventional management, although this was not the case for Araneae, Heteroptera and Auchenorrhyncha when analyzed separately. On the contrary, arthropod abundance, vascular plant diversity and also yield and fodder quality did not considerably differ between organic and conventional grasslands. Analyses did not reveal differences in the effect of organic management among grassland types. None of the recorded abiotic and biotic parameters showed a significant trend with time since transition to organic management, except soil organic phosphorus concentrations which decreased with time. This implies that permanent grasslands respond slower and probably weaker to organic management than crop fields do. However, as land-use intensity and inorganic soil phosphorus concentrations were significantly lower in organic grasslands, overcoming seed and dispersal limitation by re-introducing plant species might be needed to exploit the full ecological potential of organic grassland management. We conclude that although organic management did not automatically increase the diversity of all studied taxa, it is a reasonable and useful way to support agro-biodiversity.
Forest management is known to influence species diversity of various taxa but inconsistent or even contrasting effects are reported for arthropods. Regional differences in management as well as differences in regional species pools might be responsible for these inconsistencies, but, inter-regional replicated studies that account for regional variability are rare. We investigated the effect of forest type on the abundance, diversity, community structure and composition of two important ground-dwelling beetle families, Carabidae and Staphylinidae, in 149 forest stands distributed over three regions in Germany. In particular we focused on recent forestry history, stand age and dominant tree species, in addition to a number of environmental descriptors. Overall management effects on beetle communities were small and mainly mediated by structural habitat parameters such as the cover of forest canopy or the plant diversity on forest stands. The general response of both beetle taxa to forest management was similar in all regions: abundance and species richness of beetles was higher in older than in younger stands and species richness was lower in unmanaged than in managed stands. The abundance ratio of forest species-to-open habitat species differed between regions, but generally increased from young to old stands, from coniferous to deciduous stands and from managed to unmanaged stands. The response of both beetle families to dominant tree species was variable among regions and staphylinid richness varied in the response to recent forestry history. Our results suggest that current forest management practices change the composition of ground-dwelling beetle communities mainly by favoring generalists and open habitat species. To protect important forest beetle communities and thus the ecosystem functions and services provided by them, we suggest to shelter remaining ancient forests and to develop near-to-nature management strategies by prolonging rotation periods and increasing structural diversity of managed forests. Possible geographic variations in the response of beetle communities need to be considered in conservation-orientated forest management strategies. (C) 2014 Elsevier B.V. All rights reserved.
Intensive land use is a driving force for biodiversity decline in many ecosystems. In semi-natural grasslands, land-use activities such as mowing, grazing and fertilization affect the diversity of plants and arthropods, but the combined effects of different drivers and the chain of effects are largely unknown. In this study we used structural equation modelling to analyse how the arthropod communities in managed grasslands respond to land use and whether these responses are mediated through changes in resource diversity or resource quantity (biomass). Plants were considered resources for herbivores which themselves were considered resources for predators. Plant and arthropod (herbivores and predators) communities were sampled on 141 meadows, pastures and mown pastures within three regions in Germany in 2008 and 2009. Increasing land-use intensity generally increased plant biomass and decreased plant diversity, mainly through increasing fertilization. Herbivore diversity decreased together with plant diversity but showed no response to changes in plant biomass. Hence, land-use effects on herbivore diversity were mediated through resource diversity rather than quantity. Land-use effects on predator diversity were mediated by both herbivore diversity (resource diversity) and herbivore quantity (herbivore biomass), but indirect effects through resource quantity were stronger. Our findings highlight the importance of assessing both direct and indirect effects of land-use intensity and mode on different trophic levels. In addition to the overall effects, there were subtle differences between the different regions, pointing to the importance of regional land-use specificities. Our study underlines the commonly observed strong effect of grassland land use on biodiversity. It also highlights that mechanistic approaches help us to understand how different land-use modes affect biodiversity.
Land-use intensification is a key driver of biodiversity change. However, little is known about how it alters relationships between the diversities of different taxonomic groups, which are often correlated due to shared environmental drivers and trophic interactions. Using data from 150 grassland sites, we examined how land-use intensification (increased fertilization, higher livestock densities, and increased mowing frequency) altered correlations between the species richness of 15 plant, invertebrate, and vertebrate taxa. We found that 54% of pairwise correlations between taxonomic groups were significant and positive among all grasslands, while only one was negative. Higher land-use intensity substantially weakened these correlations(35% decrease in rand 43% fewer significant pairwise correlations at high intensity), a pattern which may emerge as a result of biodiversity declines and the breakdown of specialized relationships in these conditions. Nevertheless, some groups (Coleoptera, Heteroptera, Hymenoptera and Orthoptera) were consistently correlated with multidiversity, an aggregate measure of total biodiversity comprised of the standardized diversities of multiple taxa, at both high and lowland-use intensity. The form of intensification was also important; increased fertilization and mowing frequency typically weakened plant-plant and plant-primary consumer correlations, whereas grazing intensification did not. This may reflect decreased habitat heterogeneity under mowing and fertilization and increased habitat heterogeneity under grazing. While these results urge caution in using certain taxonomic groups to monitor impacts of agricultural management on biodiversity, they also suggest that the diversities of some groups are reasonably robust indicators of total biodiversity across a range of conditions.
Are gastropods, rather than ants, important dispersers of seeds of myrmecochorous forest herbs?
(2012)
Seed dispersal by ants (myrmecochory) is widespread, and seed adaptations to myrmecochory are common, especially in the form of fatty appendices (elaiosomes). In a recent study, slugs were identified as seed dispersers of myrmecochores in a central European beech forest. Here we used 105 beech forest sites to test whether myrmecochore presence and abundance is related to ant or gastropod abundance and whether experimentally exposed seeds are removed by gastropods. Myrmecochorous plant cover was positively related to gastropod abundance but was negatively related to ant abundance. Gastropods were responsible for most seed removal and elaiosome damage, whereas insects (and rodents) played minor roles. These gastropod effects on seeds were independent of region or forest management. We suggest that terrestrial gastropods can generally act as seed dispersers of myrmecochorous plants and even substitute myrmecochory, especially where ants are absent or uncommon.
Differential responses of herbivores and herbivory to management in temperate Eeuropean beech
(2014)
Forest management not only affects biodiversity but also might alter ecosystem processes mediated by the organisms, i.e. herbivory the removal of plant biomass by plant-eating insects and other arthropod groups. Aiming at revealing general relationships between forest management and herbivory we investigated aboveground arthropod herbivory in 105 plots dominated by European beech in three different regions in Germany in the sun-exposed canopy of mature beech trees and on beech saplings in the understorey. We separately assessed damage by different guilds of herbivores, i.e. chewing, sucking and scraping herbivores, gall-forming insects and mites, and leaf-mining insects. We asked whether herbivory differs among different forest management regimes (unmanaged, uneven-aged managed, even-aged managed) and among age-classes within even-aged forests. We further tested for consistency of relationships between regions, strata and herbivore guilds. On average, almost 80% of beech leaves showed herbivory damage, and about 6% of leaf area was consumed. Chewing damage was most common, whereas leaf sucking and scraping damage were very rare. Damage was generally greater in the canopy than in the understorey, in particular for chewing and scraping damage, and the occurrence of mines. There was little difference in herbivory among differently managed forests and the effects of management on damage differed among regions, strata and damage types. Covariates such as wood volume, tree density and plant diversity weakly influenced herbivory, and effects differed between herbivory types. We conclude that despite of the relatively low number of species attacking beech; arthropod herbivory on beech is generally high. We further conclude that responses of herbivory to forest management are multifaceted and environmental factors such as forest structure variables affecting in particular microclimatic conditions are more likely to explain the variability in herbivory among beech forest plots.
Land-use intensification is a major driver of biodiversity loss(1,2). Alongside reductions in local species diversity, biotic homogenization at larger spatial scales is of great concern for conservation. Biotic homogenization means a decrease in beta-diversity (the compositional dissimilarity between sites). Most studies have investigated losses in local (alpha)-diversity(1,3) and neglected biodiversity loss at larger spatial scales. Studies addressing beta-diversity have focused on single or a few organism groups (for example, ref. 4), and it is thus unknown whether land-use intensification homogenizes communities at different trophic levels, above-and belowground. Here we show that even moderate increases in local land-use intensity (LUI) cause biotic homogenization across microbial, plant and animal groups, both above- and belowground, and that this is largely independent of changes in alpha-diversity. We analysed a unique grassland biodiversity dataset, with abundances of more than 4,000 species belonging to 12 trophic groups. LUI, and, in particular, high mowing intensity, had consistent effects on beta-diversity across groups, causing a homogenization of soil microbial, fungal pathogen, plant and arthropod communities. These effects were nonlinear and the strongest declines in beta-diversity occurred in the transition from extensively managed to intermediate intensity grassland. LUI tended to reduce local alpha-diversity in aboveground groups, whereas the alpha-diversity increased in belowground groups. Correlations between the alpha-diversity of different groups, particularly between plants and their consumers, became weaker at high LUI. This suggests a loss of specialist species and is further evidence for biotic homogenization. The consistently negative effects of LUI on landscape-scale biodiversity underscore the high value of extensively managed grasslands for conserving multitrophic biodiversity and ecosystem service provision. Indeed, biotic homogenization rather than local diversity loss could prove to be the most substantial consequence of land-use intensification.
Species diversity promotes the delivery of multiple ecosystem functions (multifunctionality). However, the relative functional importance of rare and common species in driving the biodiversity multifunctionality relationship remains unknown. We studied the relationship between the diversity of rare and common species (according to their local abundances and across nine different trophic groups), and multifunctionality indices derived from 14 ecosystem functions on 150 grasslands across a land use intensity (LUI) gradient. The diversity of above- and below-ground rare species had opposite effects, with rare above-ground species being associated with high levels of multifunctionality, probably because their effects on different functions did not trade off against each other. Conversely, common species were only related to average, not high, levels of multifunctionality, and their functional effects declined with LUI. Apart from the community level effects of diversity, we found significant positive associations between the abundance of individual species and multifunctionality in 6% of the species tested. Species specific functional effects were best predicted by their response to LUI: species that declined in abundance with land use intensification were those associated with higher levels of multifunctionality. Our results highlight the importance of rare species for ecosystem multifunctionality and help guiding future conservation priorities.
We studied the effect of three major forest management types (unmanaged beech, selection beech, and age class forests) and stand variables (SMId, soil pH, proportion of conifers, litter cover, deadwood cover, rock cover and cumulative cover of woody trees and shrubs) on bryophyte species richness in 1050 forest plots in three regions in Germany. In addition, we analysed the species richness of four ecological guilds of bryophytes according to their colonized substrates (deadwood, rock, soil, bark) and the number of woodland indicator bryophyte species. Beech selection forests turned out to be the most species rich management type, whereas unmanaged beech forests revealed even lower species numbers than age-class forests. Increasing conifer proportion increased bryophyte species richness but not the number of woodland indicator bryophyte species. The richness of the four ecological guilds mainly responded to the abundance of their respective substrate. We conclude that the permanent availability of suitable substrates is most important for bryophyte species richness in forests, which is not stringently linked to management type. Therefore, managed age-class forests and selection forests may even exceed unmanaged forests in bryophyte species richness due to higher substrate supply and therefore represent important habitats for bryophytes. Typical woodland indicator bryophytes and their species richness were negatively affected by SMId (management intensity) and therefore better indicate forest integrity than the species richness of all bryophytes. Nature conservation efforts should focus on the reduction of management intensity. Moreover, maintaining and increasing a variability of substrates and habitats, such as coarse woody debris, increasing structural heterogeneity by retaining patches with groups of old, mature to over-mature trees in managed forests, maintaining forest climate conditions by silvicultural methods that assure stand continuity, e.g. by selection cutting rather than clear cutting and shelterwood logging might promote bryophyte diversity and in particular the one of woodland indicator bryophytes.
Management intensity modifies soil properties, e.g., organic carbon (C-org) concentrations and soil pH with potential feedbacks on plant diversity. These changes might influence microbial P concentrations (P-mic) in soil representing an important component of the Pcycle. Our objectives were to elucidate whether abiotic and biotic variables controlling P-mic concentrations in soil are the same for forests and grasslands, and to assess the effect of region and management on P-mic concentrations in forest and grassland soils as mediated by the controlling variables. In three regions of Germany, Schwabische Alb, Hanich-Dun, and Schorfheide-Chorin, we studied forest and grassland plots (each n=150) differing in plant diversity and land-use intensity. In contrast to controls of microbial biomass carbon (C-mic), P-mic was strongly influenced by soil pH, which in turn affected phosphorus (P) availability and thus microbial Puptake in forest and grassland soils. Furthermore, P-mic concentrations in forest and grassland soils increased with increasing plant diversity. Using structural equation models, we could show that soil C-org is the profound driver of plant diversity effects on P-mic in grasslands. For both forest and grassland, we found regional differences in P-mic attributable to differing environmental conditions (pH, soil moisture). Forest management and tree species showed no effect on P-mic due to a lack of effects on controlling variables (e.g., C-org). We also did not find management effects in grassland soils which might be caused by either compensation of differently directed effects across sites or by legacy effects of former fertilization constraining the relevance of actual practices. We conclude that variables controlling P-mic or C-mic in soil differ in part and that regional differences in controlling variables are more important for P-mic in soil than those induced by management.
Supporting species persistence may involve (re)connecting suitable habitats. However, for many declining species habitat suitability and drivers of establishment are poorly known. We addressed this experimentally for a declining flagship species of dry grasslands in Germany, Armeria maritima subsp. elongata. In three regions, we sowed seeds from each of eight source populations back to their origin and to eight apparently suitable, but currently unoccupied, habitats close to the source populations. Overall, seeds germinated and seedlings established equally well in occupied and potential sites indicating that suitable habitats are available, but lack seed input. Germination and establishment varied among sowing sites. Moreover, seeds from populations of lower current connectivity established less well in new sites, and establishment was more variable among seeds from smaller than from larger populations, possibly reflecting genetic consequences of habitat fragmentation. Further, establishment across different new environments differed between seeds from different populations. As this was neither related to a home-away contrast nor to geographic or environmental distance between sites it could not clearly be attributed to local adaptation. To promote long-term persistence within this dry-grassland meta-population context we suggest increasing the density of suitable habitats and supporting dispersal connecting multiple sites, e.g. by promoting sheep transhumance, to increase current populations and their connectivity, and to colonise suitable habitats with material from different sources. We suggest that sowing experiments with characteristic species, including multiple source populations and multiple recipient sites, should be used regularly to inform connecting efforts in plant conservation.
1. Ski resorts increasingly affect alpine ecosystems through enlargement of ski pistes, machine-grading of ski piste areas and increasing use of artificial snow. 2. In 12 Swiss alpine ski resorts, we investigated the effects of ski piste management on vegetation structure and composition using a pairwise design of 38 plots on ski pistes and 38 adjacent plots off-piste. 3. Plots on ski pistes had lower species richness and productivity, and lower abundance and cover of woody plants and early flowering species, than reference plots. Plots on machine-graded pistes had higher indicator values for nutrients and light, and lower vegetation cover, productivity, species diversity and abundance of early flowering and woody plants. Time since machine-grading did not mitigate the impacts of machine-grading, even for those plots where revegetation had been attempted by sowing. 4. The longer artificial snow had been used on ski pistes (2-15 years), the higher the moisture and nutrient indicator values. Longer use also affected species composition by increasing the abundance of woody plants, snowbed species and late-flowering species, and decreasing wind-edge species. 5. Synthesis and applications. All types of ski piste management cause deviations from the natural structure and composition of alpine vegetation, and lead to lower plant species diversity. Machine-grading causes particularly severe and lasting impacts on alpine vegetation, which are mitigated neither by time nor by revegetation measures. The impacts of artificial snow increase with the period of time since it was first applied to ski piste vegetation. Extensive machine-grading and snow production should be avoided, especially in areas where nutrient and water input are a concern. Ski pistes should not be established in areas where the alpine vegetation has a high conservation value
The important fodder grass Poa alpina L. occurs at several ploidy levels with common aneuploidy. We isolated and characterized five polymorphic microsatellite markers for the study of molecular genetic variation of this species. As first examples of the value of the developed markers for population genetic analyses, we show that plants with more chromosomes have more microsatellite bands and that isolation by distance plays a small role in shaping microsatellite diversity of P. alpina in the Swiss Alps
Habitat fragmentation is known to cause genetic differentiation between small populations of rare species and decrease genetic variation within such populations. However, common species with recently fragmented populations have rarely been studied in this context. We investigated genetic variation and its relationship to population size and geographical isolation of populations of the common plant species, Lychnis flos-cuculi L., in fragmented fen grasslands. We analysed 467 plants from 28 L. flos-cuculi populations of different sizes (60 000-54 000 flowering individuals) in northeastern Switzerland using seven polymorphic microsatellite loci. Genetic differentiation between populations is small (F-ST = 0.022; AMOVA; P < 0.001), suggesting that gene flow among populations is still high or that habitat fragmentation is too recent to result in pronounced differentiation. Observed heterozygosity (H-O = 0.44) significantly deviates from Hardy-Weinberg equilibrium, and within-population inbreeding coefficient F-IS is high (0.30-0.59), indicating a mixed mating breeding system with substantial inbreeding in L. flos-cuculi. Gene diversity is the only measure of genetic variation which decreased with decreasing population size (R = 0.42; P < 0.05). While our results do not indicate pronounced effects of habitat fragmentation on genetic variation in the still common L. flos-cuculi, the lower gene diversity of smaller populations suggests that the species is not entirely unaffected
Rapid decay of diversity-productivity relationships after invasion of experimental plant communities
(2004)
Molecules often fragment after photoionization in the gas phase. Usually, this process can only be investigated spectroscopically as long as there exists electron correlation between the photofragments. Important parameters, like their kinetic energy after separation, cannot be investigated. We are reporting on a femtosecond time-resolved Auger electron spectroscopy study concerning the photofragmentation dynamics of thymine. We observe the appearance of clearly distinguishable signatures from thymines neutral photofragment isocyanic acid. Furthermore, we observe a time-dependent shift of its spectrum, which we can attribute to the influence of the charged fragment on the Auger electron. This allows us to map our time-dependent dataset onto the fragmentation coordinate. The time dependence of the shift supports efficient transformation of the excess energy gained from photoionization into kinetic energy of the fragments. Our method is broadly applicable to the investigation of photofragmentation processes.
In this paper, we investigate HNCO by resonant and nonresonant Auger electron spectroscopy at the K-edges of carbon, nitrogen, and oxygen, employing soft X-ray synchrotron radiation. In comparison with the isosteric but linear CO2 molecule, spectra of the bent HNCO molecule are similar but more complex due to its reduced symmetry, wherein the degeneracy of the π-orbitals is lifted. Resonant Auger electron spectra are presented at different photon energies over the first core-excited 1s → 10a′ resonance. All Auger electron spectra are assigned based on ab initio configuration interaction computations combined with the one-center approximation for Auger intensities and moment theory to consider vibrational motion. The calculated spectra were scaled by a newly introduced energy scaling factor, and generally, good agreement is found between experiment and theory for normal as well as resonant Auger electron spectra. A comparison of resonant Auger spectra with nonresonant Auger structures shows a slight broadening as well as a shift of the former spectra between −8 and −9 eV due to the spectating electron. Since HNCO is a small molecule and contains the four most abundant atoms of organic molecules, the reported Auger electron decay spectra will provide a benchmark for further theoretical approaches in the computation of core electron spectra.
Moving arms
(2018)
Embodied cognition postulates a bi-directional link between the human body and its cognitive functions. Whether this holds for higher cognitive functions such as problem solving is unknown. We predicted that arm movement manipulations performed by the participants could affect the problem-solving solutions. We tested this prediction in quantitative reasoning tasks that allowed two solutions to each problem (addition or subtraction). In two studies with healthy adults (N=53 and N=50), we found an effect of problem-congruent movements on problem solutions. Consistent with embodied cognition, sensorimotor information gained via right or left arm movements affects the solution in different types of problem-solving tasks.
Bryophytes constitute an important and permanent component of the grassland flora and diversity in Europe. As most bryophyte species are sensitive to habitat change, their diversity is likely to decline following land-use intensification. Most previous studies on bryophyte diversity focused on specific habitats of high bryophyte diversity, such as bogs, montane grasslands, or calcareous dry grasslands. In contrast, mesic grasslands are rarely studied, although they are the most common grassland habitat in Europe. They are secondary vegetation, maintained by agricultural use and thus, are influenced by different forms of land use. We studied bryophyte species richness in three regions in Germany, in 707 plots of 16 m(2) representing different land-use types and environmental conditions. Our study is one of the few to inspect the relationships between bryophyte richness and land use across contrasting regions and using a high number of replicates. Among the managed grasslands, pastures harboured 2.5 times more bryophyte species than meadows and mown pastures. Similarly, bryophyte cover was about twice as high in fallows and pastures than in meadows and mown pastures. Among the pastures, bryophyte species richness was about three times higher in sheep grazed plots than in the ones grazed by cattle or horses. In general, bryophyte species richness and cover was more than 50% lower in fertilized than in unfertilized plots. Moreover, the amount of suitable substrates was linked to bryophyte diversity. Species richness of bryophytes growing on stones increased with stone cover, and the one of bryophytes growing on bark and deadwood increased with larger values of woody plant species and deadwood cover. Our findings highlight the importance of low-intensity land use and high structural heterogeneity for bryophyte conservation. They also caution against an intensification of traditionally managed pastures. In the light of our results, we recommend to maintain low-intensity sheep grazing on sites with low productivity, such as slopes on shallow soils.
Plant functional traits reflect individual and community ecological strategies. They allow the detection of directional changes in community dynamics and ecosystemic processes, being an additional tool to assess biodiversity than species richness. Analysis of functional patterns in plant communities provides mechanistic insight into biodiversity alterations due to anthropogenic activity. Although studies have consi-dered of either anthropogenic management or nutrient availability on functional traits in temperate grasslands, studies combining effects of both drivers are scarce. Here, we assessed the impacts of management intensity (fertilization, mowing, grazing), nutrient stoichiometry (C, N, P, K), and vegetation composition on community-weighted means (CWMs) and functional diversity (Rao's Q) from seven plant traits in 150 grasslands in three regions in Germany, using data of 6 years. Land use and nutrient stoichiometry accounted for larger proportions of model variance of CWM and Rao's Q than species richness and productivity. Grazing affected all analyzed trait groups; fertilization and mowing only impacted generative traits. Grazing was clearly associated with nutrient retention strategies, that is, investing in durable structures and production of fewer, less variable seed. Phenological variability was increased. Fertilization and mowing decreased seed number/mass variability, indicating competition-related effects. Impacts of nutrient stoichiometry on trait syndromes varied. Nutrient limitation (large N:P, C:N ratios) promoted species with conservative strategies, that is, investment in durable plant structures rather than fast growth, fewer seed, and delayed flowering onset. In contrast to seed mass, leaf-economics variability was reduced under P shortage. Species diversity was positively associated with the variability of generative traits. Synthesis. Here, land use, nutrient availability, species richness, and plant functional strategies have been shown to interact complexly, driving community composition, and vegetation responses to management intensity. We suggest that deeper understanding of underlying mechanisms shaping community assembly and biodiversity will require analyzing all these parameters.
Biodiversity-multifunctionality relationships depend on identity and number of measured functions
(2017)
Biodiversity ensures ecosystem functioning and provisioning of ecosystem services, but it remains unclear how biodiversity-ecosystem multifunctionality relationships depend on the identity and number of functions considered. Here, we demonstrate that ecosystem multifunctionality, based on 82 indicator variables of ecosystem functions in a grassland biodiversity experiment, increases strongly with increasing biodiversity. Analysing subsets of functions showed that the effects of biodiversity on multifunctionality were stronger when more functions were included and that the strength of the biodiversity effects depended on the identity of the functions included. Limits to multifunctionality arose from negative correlations among functions and functions that were not correlated with biodiversity. Our findings underline that the management of ecosystems for the protection of biodiversity cannot be replaced by managing for particular ecosystem functions or services and emphasize the need for specific management to protect biodiversity. More plant species from the experimental pool of 60 species contributed to functioning when more functions were considered. An individual contribution to multifunctionality could be demonstrated for only a fraction of the species.
Specialisation and diversity of multiple trophic groups are promoted by different forest features
(2019)
While forest management strongly influences biodiversity, it remains unclear how the structural and compositional changes caused by management affect different community dimensions (e.g. richness, specialisation, abundance or completeness) and how this differs between taxa. We assessed the effects of nine forest features (representing stand structure, heterogeneity and tree composition) on thirteen above- and belowground trophic groups of plants, animals, fungi and bacteria in 150 temperate forest plots differing in their management type. Canopy cover decreased light resources, which increased community specialisation but reduced overall diversity and abundance. Features increasing resource types and diversifying microhabitats (admixing of oaks and conifers) were important and mostly affected richness. Belowground groups responded differently to those aboveground and had weaker responses to most forest features. Our results show that we need to consider forest features rather than broad management types and highlight the importance of considering several groups and community dimensions to better inform conservation.
Tree species diversity can positively affect the multifunctionality of forests. This is why conifer monocultures of Scots pine and Norway spruce, widely promoted in Central Europe since the 18th and 19th century, are currently converted into mixed stands with naturally dominant European beech. Biodiversity is expected to benefit from these mixtures compared to pure conifer stands due to increased abiotic and biotic resource heterogeneity. Evidence for this assumption is, however, largely lacking. Here, we investigated the diversity of vascular plants, bryophytes and lichens at the plot (alpha diversity) and at the landscape (gamma diversity) level in pure and mixed stands of European beech and conifer species (Scots pine, Norway spruce, Douglas fir) in four regions in Germany. We aimed to identify compositions of pure and mixed stands in a hypothetical forest landscape that can optimize gamma diversity of vascular plants, bryophytes and lichens within regions. Results show that gamma diversity of the investigated groups is highest when a landscape comprises different pure stands rather than tree species mixtures at the stand scale. Species mainly associated with conifers rely on light regimes that are only provided in pure conifer forests, whereas mixtures of beech and conifers are more similar to beech stands. Combining pure beech and pure conifer stands at the landscape scale can increase landscape level biodiversity and conserve species assemblages of both stand types, while landscapes solely composed of stand scale tree species mixtures could lead to a biodiversity reduction of a combination of investigated groups of 7 up to 20%.
The growth form along the continuum from compact phalanx plants to more loosely packed guerilla plants is an important life-history trait in clonal plants. Prerequisite for its evolution is heritable genetic variation. Starting with 102 genotypes of the stoloniferous herb Ranunculus reptans, we performed one selection experiment on spatial spread per rosette as measure of guerillaness (broad-sense heritability 0.198) and another on plasticity in this trait in response to competition (broad-sense heritability 0.067). After two generations, spatial spread was 36.9% higher in the high line than in the low line (realized heritability +/- SE 0.149 +/- 0.039). Moreover, compared with the low line genotypes of the high line had fewer rosettes, a lower proportion of flowering rosettes, a higher proportion of rooted rosettes, more branches per rosette, longer internodes and longer leaves. In the second experiment, we found no significant direct response to selection for high and low plasticity in spatial spread (realized heritability +/- SE - 0.029 +/- 0.063), despite a significant correlated response in plasticity in the length of the first three stolon internodes. Our study indicates a high potential for further evolution of the clonal growth form in R. reptans, but not for its plasticity, and it demonstrates that the clonal growth form does not evolve independently of other clonal life- history characteristics
A major aim in ecology is identifying determinants of invasiveness. We performed a meta-analysis of 117 field or experimental-garden studies that measured pair-wise trait differences of a total of 125 invasive and 196 non-invasive plant species in the invasive range of the invasive species. We tested whether invasiveness is associated with performance-related traits (physiology, leaf-area allocation, shoot allocation, growth rate, size and fitness), and whether such associations depend on type of study and on biogeographical or biological factors. Overall, invasive species had significantly higher values than non-invasive species for all six trait categories. More trait differences were significant for invasive vs. native comparisons than for invasive vs. non-invasive alien comparisons. Moreover, for comparisons between invasive species and native species that themselves are invasive elsewhere, no trait differences were significant. Differences in physiology and growth rate were larger in tropical regions than in temperate regions. Trait differences did not depend on whether the invasive alien species originates from Europe, nor did they depend on the test environment. We conclude that invasive alien species had higher values for those traits related to performance than non-invasive species. This suggests that it might become possible to predict future plant invasions from species traits.
Local adaption of the clonal plant Ranunculus reptans to flooding along a small-scale gradient.
(2004)
Aims: Factors limiting distributions of species are fundamental to ecology and evolution but have rarely been addressed experimentally for multiple species. The conspicuous linear distribution patterns of plant species confined to river corridors in the Central European lowlands constitute an especially long-standing distribution puzzle. We experimentally tested our novel hypothesis that the tolerance of species to river corridor conditions is independent of the degree of confinement to river corridor habitats, but that species not confined to river corridors are better able to take advantage of the more benign non-river corridor conditions. Methods: We grew 42 herbaceous species differing in their confinement to river corridors in a common garden experiment on loamy soil typical for river corridor areas and sandy soil typical for non-river corridor areas, and with and without a flooding period. For a subset of species, we grew plants of both river corridor and non-river corridor origin to test for adaptation to river corridor conditions. Important findings: Species more confined to river corridor areas benefited less from the more benign non-flooded and non-river corridor soil conditions than species of wider distributional range did. For subsets of 7 and 12 widespread species, the response to flooding and soil origin, respectively, did not differ between plants from river corridor sites and plants from other sites, suggesting that the habitat tolerance of widespread species is clue to phenotypic plasticity rather than to local adaptation. Overall, we found clear support for our novel hypothesis that species not confined to river corridors are more able to take advantage of the more benign non-river corridor conditions. Our study provides a general hypothesis on differences between species confined to stressful habitats and widespread species out for test in further multispecies comparative experiments.
We tested whether neighborhood density affects the clonal life history of the stoloniferous plant Ranunculus reptans through selection and genetic drift. After three generations of sexual reproduction of 16 low- and 16 high- density lines, we studied traits related to growth form and reproduction in a common competition free environment. A 7.7% lower branching frequency and slightly longer internodes indicated an evolutionary shift towards a less compact growth form under high neighborhood density, but because stolons grew also more vertically, horizontal spread per ramet was slightly decreased. Neighborhood density had no directional effects on the evolution of allocation to sexual and vegetative reproduction in R. reptans. Variation among replicated high-density lines was significantly lower than among replicated low-density lines in both growth form and reproductive characteristics, indicating less pronounced genetic drift under high neighborhood density. This study demonstrates that a clonal plant can respond to selection imposed by neighborhood density. Moreover, it shows that the effect of random genetic drift increases with decreasing neighborhood density. In a declining species, such as R. reptans in central Europe, this may lower the potential for adaptive evolutionary change and increase extinction risk
The high potential fitness benefit of phenotypic plasticity tempts us to expect phenotypic plasticity as a frequent adaptation to environmental heterogeneity. Examples of proven adaptive plasticity in plants, however, are scarce and most plastic responses actually may be 'passive' rather than adaptive. This suggests that frequently requirements for the evolution of adaptive plasticity are not met or that such evolution is impeded by constraints. Here we outline requirements and potential constraints for the evolution of adaptive phenotypic plasticity, identify open questions, and propose new research approaches. Important open questions concern the genetic background of plasticity, genetic variation in plasticity, selection for plasticity in natural habitats, and the nature and occurrence of costs and limits of plasticity. Especially promising tools to address these questions are selection gradient analysis, meta-analysis of studies on genotype-by-environment interactions, QTL analysis, cDNA-microarray scanning and quantitative PCR to quantify gene expression, and two-dimensional gel electrophoresis to quantify protein expression. Studying plasticity along the pathway from gene expression to the phenotype and its relationship with fitness will help us to better understand why adaptive plasticity is not more universal, and to more realistically predict the evolution of plastic responses to environmental change
The relationship of different types of grassland use with plant species richness and composition ( functional groups of herbs, legumes, and grasses) has so far been studied at small regional scales or comprising only few components of land use. We comprehensively studied the relationship between abandonment, fertilization, mowing intensity, and grazing by different livestock types on plant diversity and composition of 1514 grassland sites in three regions in North-East, Central and South-West Germany. We further considered environmental site conditions including soil type and topographical situation. Fertilized grasslands showed clearly reduced plant species diversity (-15% plant species richness, -0.1 Shannon diversity on fertilized grasslands plots of 16m(2)) and changed composition (-3% proportion of herb species), grazing had the second largest effects and mowing the smallest ones. Among the grazed sites, the ones grazed by sheep had higher than average species richness (+27%), and the cattle grazed ones lower (-42%). Further, these general results were strongly modulated by interactions between the different components of land use and by regional context: land-use effects differed largely in size and sometimes even in direction between regions. This highlights the importance of comparing different regions and to involve a large number of plots
Assessing diversity is among the major tasks in ecology and conservation science. In ecological and conservation studies, epiphytic cryptogams are usually sampled up to accessible heights in forests. Thus, their diversity, especially of canopy specialists, likely is underestimated. If the proportion of those species differs among forest types, plot-based diversity assessments are biased and may result in misleading conservation recommendations. We sampled bryophytes and lichens in 30 forest plots of 20 m x 20 m in three German regions, considering all substrates, and including epiphytic litter fall. First, the sampling of epiphytic species was restricted to the lower 2 m of trees and shrubs. Then, on one representative tree per plot, we additionally recorded epiphytic species in the crown, using tree climbing techniques. Per tree, on average 54% of lichen and 20% of bryophyte species were overlooked if the crown was not been included. After sampling all substrates per plot, including the bark of all shrubs and trees, still 38% of the lichen and 4% of the bryophyte species were overlooked if the tree crown of the sampled tree was not included. The number of overlooked lichen species varied strongly among regions. Furthermore, the number of overlooked bryophyte and lichen species per plot was higher in European beech than in coniferous stands and increased with increasing diameter at breast height of the sampled tree. Thus, our results indicate a bias of comparative studies which might have led to misleading conservation recommendations of plot-based diversity assessments.