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Which tree species is “climate fit”? The Tree App helps to decide

The new Tree App helps in all locations in Switzerland’s forests to identify the tree species that will also grow in a warmer and drier climate.

Written by Keith Anderson

Which tree species is suitable for a forest location in the future when the climate changes? This question is asked repeatedly by many forest managers and owners, for example when tending young stands, or when thinning mixed stands or planting trees. The question also arises more frequently during specific events that have a lasting impact on the forest, such as storms or pest infestations. Here, the Tree App can help, because it indicates the advisable tree species on the mobile phone and also directly on the pc.  

The Tree App indicates advisable tree species. (Photo: Christoph Dürr)

The selection of suitable tree species is one of the core tasks of forestry professionals. Differences in temperature, rainfall, and soil quality determine where each tree species is best suited. In order to assess this, the Swiss forest sites were classified according to their ecological conditions in around 300 so-called “location types”.  These are already used by forestry experts to judge the suitability of tree species in forests.

Given that by the end of the 21st century it will be significantly warmer and in summer dryer, the appropriateness of tree species where they grow today will change. All forest managers face the challenge of promoting tree species that will prosper in a location not only today but also in the future. Trees species that thrive in warm conditions such as oaks will find in the future that they will also grow well at higher altitudes than today, and drought sensitive species such as spruce will be successively less vital at lower altitudes.  

Whether you are a professional or simply interested in potential future tree species – the Tree App helps to decide on the selection of sustainable tree species. (Photo: Keith Anderson)

The new Tree App helps to identify future tree species by integrating the information about soil and the climate suitability of tree species in both the current and future climate. It provides a list of recommended tree species for each location in Swiss forests. The prerequisite is that the user correctly identifies the location type, but the App also helps to do this.   

Professional users can utilize the app for example when they tend young stands and must decide which tree species they will promote. It also helps when planting to choose the future species. The application gives useful indications to forestry professionals but it cannot be used without a specialist analysis. Local foresters will be able to look at the general results from an informed point of view in deciding, based on specific local characteristics, which species can actually be selected.

How do I find and start the Tree App?

The Tree App is a «Web-App», which means it is not downloaded as an app, rather it is opened in a browser (i.e. Chrome, Edge, Firefox, Safari) the website www.tree-app.ch. This works on all internet-connected devices (mobile phone, tablet, PC).

Basic concept and method: The Tree App is based on analogies. It translates the change in temperature and rainfall into change in altitude. Climate conditions today at a particular altitude will be found at a higher altitude in the future where it is currently cooler. On the same lines, most tree species will be found at higher altitudes in the future. On average, the vegetation units will shift altitude upwardly, approximately 500-700m in the next 50 years. As a derivation of the altitudinal shifting, current and future climate conditions are being modelled for all of Switzerland.

Contact person at the Federal Office for the Environment: Pierre Alfter, Senior Silvicultural Expert, Pierre.alfter@bafu.admin.ch


Featured image: Keith Anderson, Swiss Federal Office for the Environment

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