The SPSW Summer School: Terrestrial Ecosystem Dynamics in a Changing World

2011 SPSW summer school in Mürren, Bern was hosted and organised by the Zurich-Basel Plant Science Center. Over 30 national and international students and 9 experts from Switzerland and beyond came together for vibrant discussion of “Ecosystem Dynamics in a Changing World”.

The diversity of presentations showed a strong national research expertise is existing in Switzerland dealing with the question how our ecosystems will respond to future global change: we discussed the molecular perspective of understanding molecular target genes in species responding to environmental change (Kentaro Shimizu, University of Zurich) and epigenetics bringing in an additional layer for evolutionary responses in ecosystems (Oliver Bossdorf, University of Bern). The role of plant physiology for understanding ecosystem funtions (responses to CO2, temperature, Christian Körner, University of Basel), agriculture demands (closing the food gap, Jürg Fuhrer, Agroscope Reckenholz-Tänikon ART) and also the role and response of biodiversity (biodiversity and multi-functions in ecosystems, Ansgar Kahmen, ETH Zurich/ Ecosystems and climate change, Gian-Reto Walther, BAFU, Bern) were presented. From models to scenarios to ecosystem management practices was intensively enlighted (Stefan Brönnimann, University of Bern, Christophe Randin, University of Basel, Sebastiaan Luyssaert, CEA, France).

The perspectives and disciplines that have to tackle with the summer school question also in the near future are manifold and the contribution of the different disciplines and future challenges have been the main point of the group work.

Enthusiastic comments of the participants gave us confidence that interdisciplinarity in our educational efforts is necessary: Participants stated that they will keep the questions of the other disciplines in mind for their future research and that they understood how their research discipline contributes to the overall questions.

We would like to say thank you to the speakers and students for their contribution to make the summer school a lively and inspiring event.

For the scientific organisation committee: Melanie Paschke, Christian Körner, Ansgar Kahmen, Kentaro Shimizu, all Zurich-Basel Plant Science Center, Sandrine Gouinguene, Swiss Plant Science Web

Content

Plants represent 99% of terrestrial biomass, and they provide the globe with food, fodder, fibre and genetic resources. They are central for ecosystem functioning by building and securing soils, and they affect climate through their gas exchange with the atmosphere. As atmospheric conditions change due to anthropogenic forcing of the greenhouse effect and land transformation, plants and all their dependants will either adjust, or cope (tolerate), or fade in response to these changes, with significant effects on plant community structure (winners and losers) and ecosystem functioning. Gradual climatic warming, CO₂ enrichment, changing precipitation patterns and precipitation evaporation ratios plus the occurrence of extreme events will shape the biosphere's future. As plant scientists, we can actively contribute to (1) the understanding of these consequences, (2) planning mitigation strategies and (3) create public awareness of the nature and dimension of this issue.

Organisers of the summer school are scientists from the Zurich-Basel Plant Science Center that have a strong expertise in the described sections. The summer school will integrate interdisciplinary views on the topic – from molecular to ecosystem approaches, and from science to policies. The proposed summer school will give the Ph.D. students and the future plant scientists the opportunity to understand the processes underway in changing ecosystems and review some possibilities for policy actions.

Detailed Summary Reports

Summary from “Leeway and constraints of plant and ecosystem responses to atmospheric change”.  Presented by Prof. Christian Körner, University of Basel, Switzerland

Traditionally, CO₂ concentration was assumed to be the limiting factor for plant growth. For this reason, the response of plant and community to an increase of atmospheric CO₂ has been associated with an increase in photosynthetic activity of the plants followed by an increase in growth. The photosynthetic activity of a plant rises linearly with increasing CO₂ which is then followed by saturation at a certain level. In contrary to what was expected, experiments exposing plants to artificially increased CO₂ level didn't show any increase in plant biomass. Indeed, plant growth in most environments is limited by soil nutrient availability, moisture, temperature or light. This can be clearly seen in the mountains were tree line is a result of growth inhibition by low temperature (6.5°C annual mean) rather than assimilation (source) limitation. This leads to a very novel view showing that growth actually drives assimilation (sink drives source). An exception where CO₂ has an effect on plant growth is in deep shade environments: Lianas in dense rain forests have been found to react strongly to an increase of CO₂ concentration showing that in this case CO₂ is the limiting growth factor.

Another factor influencing plant growth is heterotrophic respiration. Heterotrophic respiration is influenced by primary production and not a single function of temperature as stated before. Therefore, heterotrophic respiration has to be connected with the dynamics of NPP and through this with the other factors mentioned before. Finally, species or plant functional groups differ in their response to CO2 increase: forest trees don't react in the same way than lianas do, for example. Furthermore, the succession state of a community (expanding or stable) is also strongly influencing their response. All these examples show that the complex effects of CO2 to the environment cannot be simplified to a biochemical function, but affects biomass productivity through direct and indirect ways.

This stresses the need for large-scale and multi-factorial approaches to study and understand the impact of climate change on plants individuals and communities. It should also provide input for fine tuning of climate models that are able to examine possible influences of feedback loops between sinks and sources of carbon and will thus enable valid predictions concerning effects of climate change on plant communities. Ultimately, both experimental and modelling studies may then be used to come up with realistic mitigation and adaptation options.

Authors of this summary report: Sally Koegel, Gemma Rutten, Andreas Ensslin and Matthias Häni


Summary from: “Gene function in natura: toward prediction plastic and evolutionary responses to changing environments”. Presented by Prof. Kentaro Shimizu, University of Zurich, Switzerland

Molecular biology approaches make a large impact in the understanding of gene functions nowadays. However, as lab conditions are far from natural, evolutionary responses, e.g. origin of self-compatibility, and flowering regulation mechanisms are important to study in natura. The presented research was carried out to bridge the gap between knowledge gained by molecular biology analysis in the lab and observations from natural systems. The use of molecular tools, such as artificial reversal of evolution or mutant complementation studies, can link gene function to phenotypes observed under field conditions. Such approaches allow researchers to identify important mechanisms for plant’s responses to climate change. This knowledge could in turn improve models estimating the effect of climate change on species survival.  
Plants can follow the long-term climate trend with unpredictable fluctuations thanks to the specific mechanisms of the “molecular plant memory”. The study of gene function in natura is very complex and requires the integration of methods from evolutionary biology and ecology with analysis of large-scale data set obtained by modern molecular biology methods, such as next generation sequencing of RNA or DNA. This system biology approach can only succeed with cooperation of scientists from both molecular biology and ecology fields, as well as researchers with state of the art knowledge in modeling.
There are still a number of future challenges to be faced in the presented research field, such as collecting the data for the non-model species, studying the rapid evolution and improving data analysis approaches. The latter is especially important, as existing databases have already become insufficient for storing and processing the current amount of experimental data.
It is certainly important to monitor natural systems as it reveals ongoing evolutionary responses and phenotypic plasticity.

Authors of this summary report: Camilla Julie Koerner, Cyrill Montadon, Meng Wang, Katarina Fal

Summary from “Epigenetics and plant responses to environmental change”. Presented by Prof. Oliver Bossdorf, Institute of Plant Science,  University of Bern, Switzerland

To persist in a changing world, species need to be able to adapt to environmental changes. Since plants are largely immobile, the ability to cope with changes in the environment is of particular importance. Phenotypic plasticity and genetic variation are key elements for adaption. In addition to these well known processes, it seems that epigenetics too, could play a significant role in natural variation and evolution. Although epigenetic changes are not linked to changes in DNA sequence, they can modify the activity of particular genes either by methylation of specific DNA regions or modification of histone proteins (e.g. methylation, acetylation) However, epigenetic changes would affect the evolutionary potential of a species, only if these changes are inherited over several generations (transgenerational). Indeed, in a recent study conducted with apomictic dandelions, it was shown that stress-induced changes in DNA methylation were heritable, indicating that epigenetic mechanisms have the potential to play a role in evolution. So far little is known about how these heritable epigenetic modifications regulate gene expression and what the phenotypic consequences of such changes are. Challenging aspects for the future are: (i) to find an adequate model to study the effect of epigenetic changes, independent from genetic variation; (ii) to understand how and to what extent epigenetic modifications affect the phenotype of a species; (iii) to develop theoretical models for analysing complex epigenetic data; and (iv) to study the effect of epigenetic variation in natural populations. Although there are a lot of unanswered questions in the field, the impact of epigenetics on phenotypic variation and evolutionary processes should be closely taken into account. Especially during short-term adaption of species to environmental changes, epigenetic features may play an important role. Since mutations in the DNA sequence are not immediately reversible, epigenetic modifications represent a flexible system enabling organisms to switch between phenotypes on a multigenerational time scale.

Authors of this summary report: Melanie Binkert, Mathias Blum, Marina Gonzales Besteiro, Charles Orek

Summary from “Climate change and agricultural crops”. Presented by Prof. Jürg Fuhrer, Agroscope Reckenholz-Tänikon ART, Switzerland

Due to population growth, crop production is required to increase by 50-70% by 2050 to meet future needs for food. A further challenge in incrementing crop yields is represented by global change, as evidence suggests that recent increase in temperature and precipitation (1980-2008) had a negative impact on crop production. Because cropland currently occupies 38% of land area, the required increase in crop production should be performed without further extending cultivated areas. This requires an increase in crop productivity per land unit.
Under current management strategies the realized yields are far below what could be potentially realized. One solution to reduce this yield gap would be to have better management practices, improving weed and pest control, irrigation and fertilizers application.
Another solution consists in producing new cultivars that are more productive and better adapted to the future climate conditions (e.g. drought tolerant cultivars). Wild relatives could be used as genetic resource to increase plant resistance to biotic and abiotic stresses. This practice underlines the importance of conserving genetic diversity among agricultural plants.
Beside this, alternative crop species, better adapted to the future conditions (e.g. cassava and quinoa), could partly replace the most cultivated crops (wheat, rice and maize) to sustain food production. Crops availability for people could also be increased by reducing livestock production, as the use of crops to feed animals is energetically inefficient. These two latter strategies are however difficult to apply, as they requires people to change their food habits.  

The use of crop simulation models could help in identifying which adaptations could be taken to make crops less affected by climate change. As instance the date of sowing could be established year-by-year according to the seasonal forecast (technical adaptations), while crop type and land management could be adapted to future climate scenarios (strategic adaptations). To develop these models all climatic factors affecting crop production and their interactions should be taken into account, along with biotic factors.
Another important issue to consider is the geographical match between food demand and food production. Only if food production meets the demand on the regional rather than on the global scale we can avoid food resources to be misplaced (as it is currently happening).
In conclusion, agricultural production is a complex system, undergoing the influence of global change.  An increase in crop production will require an interdisciplinary work involving the collaboration of different research communities such as agronomists, ecologists, climatologists, farmers, plant physiologists, breeders, policy makers and social scientists.

Authors of this summary report: Adele Ferrari, Armando Lenz, Ravi Bodampalli Anjanappa,  Zsofia Juhasz


Summary from “Effects of biodiversity on ecosystem functions”. Presented by by Ansgar Kahmen, ETH Zürich, Switzerland

Biodiversity is the diversity of life and involves the diversity of genes, species and ecosystems. Although it is estimated that our world has approximately 14 million individual species, only 1.5 million species are known to the scientific community at present. Nowadays, more and more evidence is presented that climate change affects the species distribution on earth and increases the speed with which species go extinct. This gives rise to a question whether it actually matters if we lose certain species and more importantly, will it impact the way ecosystems work and function if we lose a lot of them? Results of various ecological experiments show that species can use resources in different ways, and consequently higher numbers of species use ecosystem resources more efficient. Therefore biodiversity increases the sustainability of ecosystem functioning and strengthens the stability of ecosystems. The relationship between biodiversity and ecosystem functioning can be modeled. An outcome is the relationship between biodiversity and ecosystem functioning and the fact that species occurring concurrently in an ecosystem seem to show redundant functions.
Investigating the interaction of biodiversity and ecosystem functioning is of special relevance since global change clearly affects biodiversity levels all over the world. To predict global biodiversity feedback mechanisms, e.g. the feedback effect of decreasing biodiversity on climate change must be understood. Biodiversity research might lead to improved agricultural and forestry management systems as it focuses on the importance of landscape heterogeneity, multi-cropping systems and a sufficient genetic variability of crop species.
For the future more experimental evidence is necessary to integrate more species and their individual functions. Additionally multitrophic interactions should be integrated in scientific experiments and evolving models.  The importance of high biodiversity for everyone, especially for agronomists, foresters and ecosystem managers forces us to focus on broad scale patterns., as While nowadays short-term opportunism seems to be the driving force, we need to focus on the long-term effects to develop efficient management and conservation strategies.
The general conclusion of this session should be that biodiversity affects ecosystem functioning and vice versa and therefore conservation of biodiversity should be discussed in this context. Ecosystem management might be necessary to stabilize ecosystems and maintain ecosystem functioning and productivity. Using prevention strategies for ecosystems types or diverse organisms with different functions will help to preserve a range of management options. Furthermore we want to stress the importance of policy to help preserving biodiversity and species richness.

Authors of this summary report: Rafael Wüst, Laura Junker, and Pieter van ’t Hof


Summary from “Climate change impacts on biodiversity.” Presented by Gian-Reto Walther, BAFU, Bern, Switzerland

Climate is a strong driver of plant species distribution and directly influences species interactions. With global climate warming, species are expected to expand their geographical range latitudinally and altitudinally to reach habitats that are more suitable to their environmental requirements. Climate-induced species shifts will create new species assemblages and force new ecological interactions between species as well as between species and their environment. In addition, species will show altered timing in their seasonal phenotypic development. As a consequence, synchrony of timing of ecological requirements within trophic or ecological networks might be affected. Responses of individual species to climate change are not isolated but are connected with the responses of species cohabiting in communities.
This field of research requires the interaction of related fields like physiology, ecology and genetics. In addition, actors such as foresters, farmers, and land planners might have to plan management for different species assemblages than at present. Researchers will have to reach to the public to raise awareness on the issue. Future challenges in this research field will start with a better understanding of the impacts of climate change on individual species, with more focus on the linkages between them, their interactions, as well as their feedback processes. Because of the numerous processes and interactions that influence the response of species to climate, it would be incorrect to extrapolate future responses from recent climate-induced responses. Another great challenge will be the elaboration of strategies that respect dynamic ecological processes as well as the evolutionary history of species, to preserve diversity in ecosystems.
Mitigation options will of course include improved conservation approaches as well as increased landscape connectivity in the required direction of species migration. Assisted migration of species or communities could also be an option where appropriate. In terms of adaptation, it will be important to determine whether ‘new’ species are beneficial or contribute to the maintenance of ecosystem function and services before control is considered. Because biodiversity has a major impact on the Earth’s biogeochemical cycles, on ecosystem resilience and stability, and in order to the preserve ecosystem services that humans have come to rely on, its conservation in the face of climate change is of paramount importance.

Authors of this summary report: Kulaporn Boonyaves, Emmanuelle Fréchette


Summary from “Ecosystem management for climate change mitigation: the good, the bad and the ugly.” Presented by Sebastian Luyssaert, CEA, France

Forest ecosystems are a main driver and component of global biogeochemical cycles. They cover 30% of the land area and represent 45% of the terrestrial carbon storage. Their versatile services such as climate regulation and protection of soil resources, denotes them as one of the most important terrestrial ecosystems for human wellbeing. Although, it is recognized that forests are strong carbon sinks, expansion of agricultural area drives forest conversion to support a growing global population. Conversion of natural ecosystems accelerates global change by creating a carbon debt, destructing carbon sinks and reducing biodiversity. Furthermore, management strategies of forest and plantation systems have a strong influence on carbon stocks.
Satisfying increasing demand for food and energy while reducing anthropogenic impact on natural ecosystems is challenging. First, more observational data from different ecosystems and biomes are needed to understand forest-climate feedback dynamics. Studying the interactions between forest ecosystems and the global cycles of carbon, nitrogen and water is of particular importance. Pressure on natural ecosystems for land conversion must be reduced by optimization of biofuel production at the agricultural and technical level. Changes in forest management practices should be directed to maximize carbon storage capacity, e.g. shifting to a more multipurpose management and sustainable use of forest products. Adoption of conservation practices in order to protect biodiversity is another future challenge. Practical implementation will require fundamental knowledge from various fields of plant biology and beyond. Thus, advances in plant sciences may help to attenuate human-induced ecosystem dynamics and will have important outreach consequences for climate change mitigation.  Forests have the potential to mitigate climate change but only if managed in the appropriate way or left to undisturbed conditions.  

Authors of this summary report: Aud Halbritter, Livia Atauri Miranda, Wenjing She & Stefan Trogisch


Summary from “Predicting the fate of plant species in a changing world”. Presented by Christophe Randin, University of Basel, Switzerland

As a consequence of global warming, many plant species have to either adapt to changing climatic conditions or find new habitats with suitable conditions to avoid getting extinct. The modeling of such dispersal patterns is therefore vital to predict future biodiversity and habitat location. Dr. Randin produced such models for regions in the western Alps, using high-resolution (25m) data of the Diablerets and Zermatt regions. Those regions mainly differ in their altitudinal range (375-3210m in the Diablerets study area, 1480-4634m in the Zermatt study area). When applying several different climate change scenarios, no species were expected to go extinct in the Zermatt region, while a substantial part of the species was expected to go extinct in the Diablerets region. This suggests that altitude plays a major role in plant species persistance. In another study of the Diablerets area, various dispersal types of plants (from “no dispersal” to “unlimited dispersal”), were added to the model. Here, 10-50 species out of 287 species were predicted to become extinct by the year 2100.

This was very much in contrast with previous predictions that were using much larger plots (16km), predicting up to 60% of all species becoming extinct within the same timescale. These discrepancies underline the importance of high resolution models, particularly in mountainous regions with many different habitat types and high differences in altitude. Therefore, an even higher resolution, up to plots of 1m2 in size would be vital to further improve forecasting models in regions with such a diverse topography. Also, the climatic data available of such regions rarely covers the entire climatic environment and thus makes forecasting very difficult. As a solution more data would need to be collected from weather stations optimally covering the most important ecological niches in a region. Another effect that is to be considered in future models are biotic interactions (e.g. plant-pollinator or plant-herbivore interactions), which have been largely neglected so far.

All in all, such distribution models provide a powerful tool to predict how habitats will change in respect to climatic change and which can be used to improve habitat management strategies. Moreover, this kind of studies can help to raise public awareness about the consequences of man-made climate change and could contribute to the mitigation of global change. Undoubtedly to the relief of the Swiss tourist office, Edelweiss seems to survive across all climate change scenarios.

Authors of this summary report: Dominik Klauser, Elvira de Lange, Tom van Noort & Kumar Vasudevan

Lecturers

• Oliver Bossdorf, Institute of Plant Science,  University of Bern, Switzerland.

• Stefan Brönnimann, Oeschger Centre for Climate Change Research, University of Bern.

• Jürg Fuhrer, Agroscope Reckenholz-Tänikon ART, Switzerland

• Ansgar Kahmen, Institute of Plant, Animal and Agroecosystem Sciences, ETH Zurich, Switzerland.

• Christian Körner, Institute of Botany, University of Basel, Switzerland.

• Sebastiaan Luyssaert, Laboratoire des sciences du climat et de l'environnement (LSCE), CEA, France.

• Christophe Randin, Institute of Botany, University of Basel, Switzerland.

• Kentaro Shimizu, Institute of Plant Biology, Evolutionary Functional Genomics, University of Zurich, Switzerland.

• Gian-Reto Walther, Federal Office for the Environment, Species and Biotopes section, Ittigen, Switzerland.

Program

Please click to open the pdf file: program summer school 2011 [PDF / 343 KB]

Poster Prize Winners

Every year prices for the best posters are given to PhD students during the Swiss Plant science Web Summer School.

This year the winners were

Adele Ferrari from WSL and the University of Zurich (abstract [PDF / 61 KB])

and Elvira de Lange from the University of Neuchatel (abstract [PDF / 59 KB])