Carbon dynamics : The effect of climate and land use change on soil carbon in Swiss soils

Soil organic matter plays a major role for ecosystems. However, it is threatened by global change. In the “Carbon dynamics” project we attempt to estimate how vulnerable the soil organic matter is. We assess the role of factors such as climate, soil properties and terrain and propose tools to predict the fate of soil organic matter.

  • Background (completed research project)

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    Soil organic matter plays a key role in the services provided by the soil. It is crucial for soil fertility and plays an important role in relation to climate change. However, global change (climatic and land use change) may threaten this soil organic matter. New conditions, brought about by factors such as rising temperatures or changes in plant growth patterns, may increase the loss of organic matter. This decreases its potential to provide ecosystem services. However, we do not know which soils will mainly be affected by these changes. Assessing this vulnerability is vital to protect these soils effectively.

  • Aim

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    The project assessed the soil organic matter vulnerability of Swiss forest soils and provide tools to predict it.

  • Results

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    The team analysed the vulnerability of soil organic matter at 54 Swiss forest sites, selected as representative of Switzerland as a whole. We observed that the vulnerability varies greatly between different soils. The variations can be explained by climatic factors such as moisture and soil parameters such as pH. We took samples and observed their reactions to potential changes such as temperature increases or plant growth in future climatic scenarios. It appears that plants are affected at the same level as soils when conditions change. On the basis of these results, we propose a tool based on ecosystem properties (climate, soil and terrain) to predict which soils will be the most susceptible to losing their organic matter in the future.

  • Implications for research

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    The study is based on a site selection that allows us to disentangle the importance of climatic, soil and terrain drivers for a large number of soils. Depending on the approach (controlled conditions, modelling), parameters such as pH and soil moisture explain the observed patterns and provide a powerful framework for further process-oriented studies. The study also highlights the need to consider the plant and the soil together when investigating the effect of global change on this system.

  • Implications for practice

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    All soils do not have the same vulnerability to global change. As a consequence, it is important to identify which ones may lose their carbon in larger proportions and faster than others. This would help to define specific measures to protect these soils against carbon loss.

  • Original title

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    How vulnerable is Swiss soil organic matter to climate and land use changes?