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Work starts on the fifth Swiss National Forest Inventory

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Data collection for the fifth Swiss National Forest Inventory (NFI) has just got under way. Staff from the Swiss Federal Institute for Forest, Snow and Landscape Research (WSL) have been conducting these surveys since 1983  providing vital data for forest management and forest policy. The NFI is a joint initiative of the Federal Office for the Environment (FOEN) and WSL.


WSL staff are once again taking measurements and tallies in Swiss forests as they survey a network of around 6,500 sample plots distributed evenly across Switzerland's forested areas. This fifth NFI will see them examine a ninth of the plots each year until 2026.

What standing volumes of wood are there? How much wood has grown back since the previous survey? How much have forest owners used? And how substantial are potential yields? The NFI provides answers to these questions and many more. Analysis of the data will also indicate whether the forest area is continuing to grow, as it has done over the past 35 years. Furthermore, the NFI is a mine of information on the maintenance of 'protection forests' (a category accounting for around half of Swiss forests), as well as supplying data about the tree species composition and the forest's ability to act as a habitat for flora and fauna, its recreational use and its health and vitality. One topical question it should answer is how much of an effect ash dieback is having on the number of ash trees nationwide, which have been the second commonest deciduous trees in Switzerland along with the sycamore,.  The results of the fourth NFI, to be unveiled by the FOEN and WSL in 2020, will already shed some light on this matter.


No increase in cost of NFI despite new characteristics being surveyed

The fifth NFI will be the first in which the survey teams will log small habitats on an individual tree (e.g. tree hollows, bark pockets, perennial fungi and ivy growth) (Figure 1), non-native herbaceous plants causing problems in a forest environment and any remaining visible rootstocks. It will therefore provide new and more precise information about forest biodiversity. In addition, thanks to periodic rounds of interviews with foresters, the NFI survey teams will know exactly how easy or difficult it is to harvest the wood and remove it from the forest. This supplies a key indicator for the timber industry, namely where economically useful wood potential can still be found in Swiss forests.

The additional characteristics now being recorded, were determined based on a needs analysis. It also examined which characteristics could be eliminated in future without compromising the quality and continuity of the surveys. As a result, there has been no increase in the cost of the NFI despite the additional characteristics being surveyed.


Report on results of fourth NFI to be published in 2020

The surveys for the fifth NFI follow on seamlessly from those of the fourth, which culminated in late March 2018 with periodic interviews with more than 800 foresters and cantonal forestry services. A report setting out the results will be published in 2020. This will both extensively analyse and interpret the recorded data and serve as a basis for the FOEN in forest policy decision-making. Interim results for the fourth NFI from the first five survey years 2009-2013 have already been published and are available to download.


Opportunity for the media to spend time with survey teams in the field

Every year, the three NFI survey teams will be out and about in all parts of the country (see map), collecting data from the sample plots (Figures 3 and 4) and interviewing local foresters. Members of the media are always welcome to spend time with a survey team while it carries out its work and report live on its data collection activities in Swiss forests. To arrange this, please call or email Fabrizio Cioldi, operational manager of the NFI field surveys.


The NFI is a long-term national forest observation initiative. The results are based on interpretations of aerial photos, sample surveys in the forest environment, interviews with foresters and cantonal forestry services, and third-party models and data. The NFI supplies key information for sustainable forest use and protection and provides a basis for environmental and forestry decisions.

The NFI is a joint initiative of the Federal Office for the Environment (FOEN) and the Swiss Federal Institute for Forest, Snow and Landscape Research (WSL). WSL is responsible for planning and implementing data collection as well as for analysis and scientific interpretation, while the FOEN takes care of forest- and environmental-policy interpretation and drawing up implementation measures.

More information can be found at