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Research in the  Klimawald

Dendrometer at Klimawald 1.0

How do the planted tree species cope with drought, heat and frost?

In order to study the growth of the seedlings, we installed dendrometer in the Klimawald. Dendrometers use fine mechanics to measure changes in trunk diameter. The aim is to investigate how well different tree species are adapted to drought and heat stress. The strategies of the different planted species can be compared. You can follow the measurements live here:

You want to see the data in more detail? To do this, draw a box around the desired section in the diagram

The trunk diameter of a tree changes due to the growth in thickness and the fluctuations in the water condition of the tree. Different tree species react differently to drought.

Dendrometers were installed on 5 specimens each of the following 3 tree species:


European beech

Fagus sylvatica


Native, widespread deciduous tree species. Our saplings have grown well.


Sweet chestnut

Castanea sativa


Non-native deciduous tree species, origin south of the Alps. Tree species with the greatest height growth so far at Klimawald 1.0.


Wild service tree

Sorbus torminalis


Native deciduous species with good drought tolerance. Only moderate growth so far, the location at Klimawald 1.0 is probably too base-poor.

The trunk thickness of a tree changes due to growth and fluctuations in water status of the trunk. The thickness of the trunk increases permanently due to the formation of new wood and bark cells. In addition, daily fluctuations in trunk diameter can be observed. On dry and warm days, the tree loses more water through its leaves than it can absorb through its roots. Therefore, the cells in the trunk shrink during the day. At night, if there is enough water in the soil, the tree can compensate for the loss, so that the trunk becomes slightly, but measurably, thicker. During longer periods of drought or severe frost, the tree cannot replenish its water supply at night: the trunk diameter falls significantly and only increases again when enough water is available.

Thickness growth in wet years can be compared to that in dry years. It is to be expected that tree species react differently to drought.

Air temperature and precipitation

With our own weather station at Klimawald 1.0 we measure several parameters (e.g. air temperature, precipitation, air humidity and air pressure). As examples, the curves of the air temperature (maximum 365 days) and the precipitation (maximum 30 days) are shown here.

Soil moisture

In order to measure the current soil moisture at a depth of 25 cm and 50 cm, sensors are installed near the selected trees. These measure the currently available amount of water as a percentage of the maximum possible amount of water storage in the soil. After rain, a rapid increase in soil moisture can be observed. The soil constantly loses water through evaporation, sinking of the water in the direction of the groundwater table and water consumption by the plants. The current soil moisture thus shows whether there is a dry period for the plants.

Natural regeneration and survival rates at Klimawald 1.0

On our planted sites the survival rates of the seedlings and natural regeneration should be monitored regularly to contribute to the ongoing research on climate change adapted tree species. This is for example done within Bachelor or Master thesis.

One year after planting the survival rates of the planted trees was almost 90 percent. Details can be observed in the figure.


Natural regeneration also offers enormous potential for forest conversion, with about 50,000 saplings per hectare. However, it is to be expected that they will largely consist of tree species that are not or poorly adapted to climate change. Therefore, the combination of natural regeneration and artificial enrichment with alternative tree species is recommended for forest practice.

Bachelor thesis Sophia Fenninger, supervisor Gregor Aas

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