Long-term research reveals changes and adaptation possibilities

To better understand the effects of these changes and to develop adaptation strategies, HBLFA the long-term research project ClimGrass . The results of this project now also form the basis for the new research project DryGrassover the next 10 years effects of drought and heat on the grassland ecosystem .

A unique open-air experiment

The ClimGrass experimental facility. In this unique open-air experiment,

• Permanent grassland small plots with a three-cutting system
• exposed to future climate conditions with increased temperature and CO₂ concentration. Additionally, for some of the plots
• Drought was simulated using rain canopies that blocked precipitation for several weeks in the summer.

 

 

In the new DryGrass we are using the existing infrastructure with some adaptations and focusing even more strongly on the risks that will prevail for agriculture in the coming decades: drought and heat.

In addition to plant growth are also soil processes, water balance and material flows investigated using state-of-the-art instruments and methods.

Changes in the grassland ecosystem

Climate simulations conducted in recent years have shown that

• the vegetation starts significantly earlier and
• is developing faster.

Management practices such as harvesting times and fertilization must be adapted accordingly. Besides rising temperatures, drought stress plays a key role in the future of grasslands. Prolonged dry periods severely restrict growth, and plant composition also changes: drought can favor certain species and suppress others. In the long term, this leads to changes in species composition.

also Significant effects were observed in the soil. Changes in soil moisture influence the activity of microorganisms and thus important processes in the carbon and nutrient cycles. Another focus was the investigation of water flows in the soil-plant system. Studies showed that rising temperatures increase evaporation, while elevated CO₂ concentrations can sometimes lead to reduced water release by plants.

However, the combination of warming, increased CO₂, and drought alters the entire water system in the soil: water is transported through the soil more quickly and is therefore available to plants for a shorter period. This can reduce the resilience of grasslands to prolonged periods of drought.

The new research project DryGrass

To launch the new DryGrass project, the topsoil on the existing ClimGrass plots was replaced beforehand to create identical starting conditions for all new treatment variants. DryGrass focuses on how grassland ecosystems react to drought combined with heat and what adaptation strategies are possible.

A key innovation compared to ClimGrass was the integration of the usage system as a factor in the DryGrass experimental design . This allows two-, three-, and four-cut systems . To simulate drought and heat for all usage systems, rain shelters and heating infrastructure had to be significantly expanded.

Importance for agriculture and the environment

The results of the interdisciplinary research in ClimGrass show that climate change will permanently alter grassland. Earlier vegetation starts, altered yield and growth dynamics, and more frequent periods of drought are changing the grassland ecosystem and thus presenting farmers with new challenges.

The DryGrass project continues this research systematically. Its aim is to strengthen the resilience of grasslands to climate change, thereby securing both agricultural production and the diverse ecosystem services of grasslands in the long term.