Our research themes

Motivation

Life together with climate and other abiotic drivers is the basis to the state and functioning of the ecosystems. Although we do not fully understand the entirety of consequences of our doing, humanity is exploiting, in many places over-exploiting, ecosystems around the world: to gather resources, as space for human living, and for agriculture, forestry, and many other forms of use. Biodiversity and plant and animal communities are impacted by land-use change and climate change in a complex way that is not trivial to understand or yet predict. But likewise, we do not yet fully understand the consequences of changes in biodiversity for ecosystem functioning (including, for instance, consequences for climate regulation). Which is why we need to push the boundaries of our knowledge to help decision makers to steer actions towards using our ecosystems in a sustainable way and to apply appropriate climate change mitigation and adaptation measures as well as Nature conservation in an integral way.

Our activities

We use the dynamic global vegetation model LPJ-GUESS to explore ecosystem functioning, which are indicative for important services ecosystems provide to humans, and changes therein that are caused by changes in land use and management, climate change. We investigate ecosystem services related to the productivity and carbon sequestration potential of ecosystems (e.g. net primary productivity, vegetation C, soil and litter C), agricultural production (e.g. crop yield production, N leaching) and the water cycle (e.g. total water runoff, evapotranspiration). A special focus lies on the ecosystem responses to future land-use options that may include climate adaptation and mitigation options (e.g. production of bioenergy with carbon capture and storage, or avoided deforestation and reforestation or afforestation).

Another focus of our work lies on the driving role of animals in terrestrial ecosystems and their interactions with the ecosystems’ functioning and productivity. We seek to quantify both direct effects of herbivory (e.g. removal of vegetation biomass) and indirect effects (e.g. changes in plant species composition, regulation of fire frequency and intensity). Eventually we are interested to quantify the cascading effects of higher trophic levels in forms of top-down regulation on herbivory (e.g. absence/presence of apex predators, die-offs of animal functional groups) on ecosystem functioning. To do so, coupled the DGVM LPJ-GUESS with a model of heterotrophic populations (model: Madingley).

Motivation

Land provides the basis for our livelihoods – but the current extend of human influence, magnitude and rate of change of resource use is historically unprecedented and not sustainable. The way humans make use of terrestrial ecosystems clearly will have to improve, especially since changing climate and rising CO₂ concentrations will become additional key factors, which affect growing conditions for crops, pastures, and forests. With climate change, the productivity of different regions will shift, at the same time that changing population and economic growth cause new patterns of demand. As global patterns of land use change in response, those land-use changes will feed back onto climate change through, for example, the absorption or release of CO₂.

Forests are especially vulnerable to climate change, because the life-span of trees means that adaptation is slow at the ecosystem level. On the other hand, forests take up and store large amounts of carbon, and thus could help counteract climate change. Forests in Europe are strongly managed, including planting of species outside their natural range, where they are even more sensitive to droughts and increasing temperatures. Future climate- and CO₂-mediated changes in productivity will occur alongside deforestation, forest planting, and management to determine exactly what the forests of the future look like.

It is impossible to predict exactly how land use will evolve in the future, and how that evolution will affect ecosystems, the climate and society. However, policymakers and other stakeholders need to get a sense of the possibilities in order to, for example, make informed decisions about the effectiveness of possible climate change mitigation strategies.

Our activities

The Land Ecosystem Modeling Group is engaged in several lines of research using the LPJ-GUESS dynamic global vegetation model to investigate the future of land-use change in the Earth system.

We are using LPJ-GUESS to investigate how climate change, land use/cover change and agricultural management can affect soil properties and yields. With a regional focus on Eastern Africa, where severe land degradation is a major challenge, we explore how alternative crop management strategies (such as no-tillage, cover crops, fertilizer and manure application) and forest planting could restore degraded soils and return multiple benefits such as improved drought resilience, enhanced fertility, and increased carbon sequestration.

In regard to an improved consideration of managed forests, we are incorporating different types of forest management into LPJ-GUESS to explore how management has affected carbon pools and fluxes in Europe’s forests in the past, as well as how future management options can support climate change mitigation policy.

And in the Land System Modular Model (LandSyMM, https://landsymm.earth/), LPJ-GUESS is coupled with the PLUM land-use model to explore future land use (e.g., agriculture, forestry) based on simulated crop, pasture and forest productivity under different climate, and management strategies, to produce maps of land use areas and management inputs. This allows us to explore, for example, the impacts of climate change and associated land-use change on ecosystem services under a range of possible future scenarios. In work ongoing the IMOGEN climate emulator will also be coupled, seeking to better account for feedbacks between land-use change and climate change.

Motivation

How do land and climate interact? Climate is a chief co-determinant of vegetation cover and carbon, water and nutrient cycles. Climate change, including the increasing levels of CO₂ in the atmosphere, therefore will cause biomes’ boundaries to shift, and impact biodiversity and numerous processes in terrestrial ecosystems. Alterations in ecosystems biogeochemical cycles can thus feedback to climate through sources and sinks of greenhouse gases. This includes, for instance, enhanced emissions of methane from wetlands in response to warmer temperatures, or enhanced emissions of N₂O from natural and managed ecosystems. Most notably, terrestrial ecosystems at present remove annually nearly 30% of anthropogenic CO₂ emissions; how this CO₂ ‘sink’ will develop in the future remains a fundamental unknown. But vegetation properties and exchange processes related to energy and water also impact climate locally to regionally and contribute notably to warming or cooling. The manifold exchange processes between the atmosphere and land, jointly with vegetation dynamics and changes in species composition can therefore amplify or dampen climate change. In providing better understanding of land-climate interactions and climate feedbacks, science can provide an important contribution to achieving climate change mitigation goals such as specified under the Paris Agreement of the UNFCCC, or related to biodiversity under the UN Convention on Biological Diversity.

Our activities

We apply and develop the dynamic vegetation model framework LPJ-GUESS to explore shifts in natural biomes, sources and sinks of CO₂, changes in water balances and other ecosystem responses to climate change and changes in atmospheric CO₂ concentration. LPJ-GUESS is also being coupled to the climate change ‘emulator’ IMOGEN as part of LandSyMM. Work is also ongoing to turn LPJ-GUESS into a full land-surface model, which means to implement a full energy balance into the model, and to change the simulations done at daily time-step into sub-daily calculations. By coupling this new model version to atmospheric models, we will be in the position to explore regional and global biogeochemical and biophysical land-climate feedbacks.

See also International activities.