Research

This is a guide to the different fields of research covered by our Department. As your interest may be focused on a certain approach, we offer different gateways to what we do.

Ecological Issues

Climate change

Climate climate change will be one of the most pressing actual and forthcoming challenges to humanity, and will have a most devastating influence on the ecosystems of the world. The consequences for biodiversity are evident by shifts of abundance and distribution ranges of species leading to new communities. Range shifts may drive certain species up the mountains or up north both of which will lead to a decreased area which can be inhabited as range. These species will hence loose habitats, decrease in range size and/or abundance and eventually may face extinction. On the other hand, new species will follow from southern or lowland regions. The exchange of species may result in different functions of the ecosystem these species are associated with. Further, the impacts on biotic interactions such as competition, facilitation, parasitism, predator-prey or host plant-herbivore relationships are mostly unclear. It is hence unknown whether these may buffer against or accelerate the risks imposed by climate change.

Land use

Human needs determine land use and hence the composition and configuration of landscapes. The resulting landscape qualities like fragmentation and networking are important drivers for biodiversity turnover and loss. Forthcoming issues are land use conflicts arising from competition between food plants, energy plants, recreation and conservation. This sets the frame for the management and development of biodiversity.

Biological invasions

Human activities lead to the translocation of species from their home range across biogeographic boundaries into new regions. While most species do not manage to maintain self-sustaining populations, some may and become established. Few of these may even be harmful to native species, ecosystems or to forestry, agriculture, fisheries or other societal actors. This process is called biological invasions. Because some of these species have other suits of traits and serve different functions in an ecosystem compared to native species, biological invasions can have impacts on ecosystem functions and resulting services. To mitigate the impacts of biological invasions and prevent new invasions, it is crucial to properly understand the mechanisms of invasions and the impacts on native diversity and ecosystems.

Nature and species conservation

The conservation of nature and species aims to stop the decline of species and communities with special emphasis on rare and endangered species. A precondition for efficient conservation is the knowledge of the relevant processes that determine individual growth, population persistence and metapopulation functioning. Thus conservation biology encompasses studies on life history, demography, site conditions, population genetics and landscape ecology.

Patterns and processes

Species interactions

In the given setup of abiotic conditions of a landscape, species interactions between same (intraspecific) and different (interspecific) species are important drivers for biodiversity, as activity of any organisms affects the environment in which it lives. Within such a dynamic environment interactions like competition, predation, parasitism, mutualism, and detritivory moulding the composition of communities and populations take place.

Ecosystem functions

Ecosystem functions are the result of the constituting organisms and their interactions. Ecosystem functions are the basis for, e.g. water purification, oxygen production, soil formation, biomass production, biological pest regulation, pollination and many more. The components of Global Change, such as climate change, land-use change or biological invasions, alter the functional components of an ecosystem. The results be ecosystems that differ oto various degrees from previous system and may be even completely novel. We aim at understanding these functions and develop tool and management options to mitigate the impacts on ecosystems or find appropriate substitutes for beneficial functions.

Evolution

Biological systems are never static. Species continuously evolve due to mutation and complex interactions of selection and genetic drift. Genetic variation that is continuously passed on and mixed within populations by sexual reproduction is the raw material for microevolution, e.g. due to altered selection regimes like climate change. Evolution may also involve hybridization of previously separated species or populations, e.g. after introduction of alien species, or introgression of genes from crops into native species.

Distribution patterns

Species show a specific spatial pattern of occurrence, their range. This range is usually delimited by specific environmental (biotic and abiotic) parameters. Furthermore, not only species are characterised by a range but certain traits respond to specific environmental filters and hence vary in their composition. To better understand the relationships between both traits and species, we model their response to the environment. This is a prerequisite to asses impacts of climate change, land-use change or biological invasions on species and communities and their consequences for the functional composition of ecosystems. We will also use this knowledge to developi adaptation and mitigation measures buffering against these pressures.

Disturbances

In ecology disturbance is a temporary change from average conditions, often resulting in the removal of large amounts of biomass. Disturbance events like fires, floodings, windstorms or insect outbreaks vary in spatial and temporal scales and cause pronounced changes in ecosystems, communities and populations. Disturbances generate conditions that favour the success of certain species and therefore facilitate the formation of specific ecosystems and communities. These communities may exist for much longer periods than the time span of the actual disturbance. However, without recurrent disturbances communities will develop back toward pre-disturbance conditions (succession). Overall a mosaic of communities at different successional stages facilitates high levels of biodiversity.
The success of certain species is closely linked to disturbances. For example, many shade-intolerant plant species rely on disturbances (e.g. removal of trees) for successful establishment. However, very view species are able to tolerate intense disturbance regimes. The intermeditate disturbance hypothesis suggests that diversity is highest when disturbances are neither too rare nor too frequent. With low disturbance, competitive exclusion by the dominant species decreases species richness, whereas with intense disturbance regimes, only species tolerant stress persist.

Methods

Modelling

We use a plethora of different techniques to model species or trait responses to the environment as well as populationdynamics of selected species. Especially population dynamics are modelled by process-based (or rule-based) models whereas distribution patterns are mainly modelled statistically. Here we use simple niche-based models based on generalised liner models as well as advanced techniques such as autoregressive models, wavelet revised methods, generalised estimating equations or generalized boosted methods. As far as possible, we consider phylogenetic or spatial non-independence in our models.

Ecological experiments

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Genetics

We use molecular genetic methods to describe genetic patterns within and among populations and to uncover ecological processes like dispersal or inbreeding. Various genetic marker systems are used, depending on the organisms studied and research question: microsatellite markers, AFLP (amplified fragment length polymorphism), chloroplast microsatellites, plastid DNA sequences, allozymes. Most of these markers are selectively neutral. However, sometimes it is possible to directly target variation at the gene level, like MHC in vertebrates.

Monitoring

In order to assess the impacts of global change on biodiversity and ecosystems we use standard methods to regularly monitor the changes in species combination and abundance. In particular we have established an online-based monitoring scheme for German butterflies which relies upon voluntary recorders and enthusiastic colleagues. It is constantly enlarged and updated. Further we are involved in the Terrestrial Environmental Observatories (TERENO).

Data bases

Naturalists and professional ecologists analysed different aspects of ecology over the past decades across a complete range of different species, habitats or regions. Therefore, for many though far not all questions data are already available. To be analysed smoothly, it is necessary to store these data in an ordered manner, i.e. in databases with easy access. We collated and host data for public access on plant traits of the German flora (i.e. BiolFlor, www.biolflor.de) and analyse databases on plant distribution in Germany (i.e. FLORKART, www.floraweb.de, hosted by the Federal Agency for Nature Conservation) together with databases on land-cover, soil, geology and climate which are to our disposal by courtesy of other institutes.

Risk assessment

Based on a better understanding of terrestrial and freshwater biodiversity and ecosystem functioning, we develop and test methods and protocols for the assessment of large-scale environmental risks in order to minimise negative direct and indirect human impacts. Research is heavily integrated into the ALARM project (www.alarmprojet.net) focuses on assessment and forecast of changes in biodiversity and in structure, function, and dynamics of ecosystems. This relates to ecosystem services and includes the relationship between society, economy and biodiversity. In particular, risks arising from climate change, environmental chemicals, biological invasions and pollinator loss in the context of current and future European land use patterns are assessed.