The Swiss National Forest Inventory

Transcription

1 Where to find us Swiss Federal Institute for Forest, Snow and Landscape Research WSL Zürcherstrasse 111 CH-8903 Birmensdorf ZH phone Map, directions and time tables at: The Swiss National Forest Inventory Contact Urs-Beat Brändli, WSL Scientific Service NFI phone Paolo Camin, BAFU phone Internet Masthead Publisher: Swiss Federal Institute for Forest, Snow and Landscape Research WSL CH-8903 Birmensdorf ZH, 2015 You can obtain this leaflet in German, French, Italian and English from the WSL Shop, Text and editorial office: Urs-Beat Brändli, Simon Speich, WSL Layout: Sandra Gurzeler, WSL Translation: Simon and Tonia Speich Picture credits Photos: Urs-Beat Brändli, Simon Speich, WSL / Beni Basler, Aarau Aerial Photograph: 2005 swisstopo (BA057286) Maps: Kalin Müller, WSL Swiss border and lakes: Bundesamt für Statistik (BFS) GEOSTAT: G1L01, G1S01/Relief: K606-01@2004 swisstopo Climate-neutral printed matter No Landesforstinventar Inventaire forestier national Inventario forestale nazionale Inventari forestal naziunal National forest inventory

2 What does the Swiss forest look like and how does it change over time? The Swiss National Forest Inventory (NFI) tries to answer these questions. The forest fulfills many tasks: It hinders avalanches, rockfall and mudslides. The forest provides wood to be used as fuel and material for construction. It serves as a place of leisure and recreation and last but not least is home to animals and plants. Therefore, the forest has to be protected, but also managed sustainably with the clear goal of fulfilling these functions. Exact knowledge of its condition is necessary, thus an inventory. Valuable information on how the forest develops in the long run is obtained from carrying out several inventories over a long period of time. Fourth survey from 2009 to 2017 In 2009, after 1983, 1993 and 2004, an inventory of the Swiss forest started for the fourth time. This is a large scale project, if one considers that about one third of Switzerland is covered by forest. In 1981 the Federal Council decided to carry out the first NFI. It is realized by the Swiss Federal Institute for Forest, Snow and Landscape Research WSL in collaboration with the Federal Office for the Environment (FOEN). When do trees make up a forest? When does an area covered with trees count as a forest? This question can not be answered easily. Depending on purpose and motivation, different definitions of forest are used in Switzerland. The cantonal laws on forest mainly express the goal to conserve and protect the forest. On the contrary, the NFI, as a nationwide project, depends on a uniform definition and therefore gives a quantitative one. The forest definition in the NFI is based on three criteria: degree of cover, width of stocking and tree height. An area covered with trees is considered a forest if it is wider than 50 meters and if the tree crowns cover more than 20 percent of the ground area. If the plant cover is denser, then also narrower areas count as forest. Furthermore, all trees have to be taller than three meters, except for afforestations, regeneration areas, burned areas, windthrow areas, as well as shrub forests. 100% Tree canopy cover 80% 60% 40% Non-forest according to NFI Forest according to NFI 41% Jura 25% Plateau 35% Pre-Alps 27% Alps 52% Southern Alps 32% Switzerland About one third of Switzerland is covered with forest. This fraction varies regionally from one fourth to more than half. 20% 0% 5 m 15 m 25 m 35 m 45 m 55 m Width Forest definition according to the Swiss National Forest Inventory (NFI).

3 Information taken from a bird s eye view A grid with 6500 sample plots in the forest The aerial photo interpretation is the first step of the NFI. With the help of aerial photographs, specialists decide at the WSL if a surveyed area is «forest». This decision is taken every 1.4 kilometers nationwide or in places overall. These decisions will be verified later in the field. There are about 500 million trees in Switzerland far too many to investigate individually. Random sampling, however, yields adequate information. For that purpose, a 1 km-grid was mapped over Switzerland in the first NFI. It was assessed if the grid s intersections happened to be forest. If that was the case, a new sample plot was determined. In addition to the forest/non-forest decision, the interpreters collect a number of further attributes. Among others, they inspect if the ground is covered with broadleaved or coniferous trees, bushes or grass, buildings, roads, bodies of water or snow and how high these objects are. Furthermore, single trees and small groves outside the forest are measured. In comparison with older aerial photographs, for example, it can be determined where new forest is developing. Or it can be assessed how much CO2 is stored in woody biomass. The second NFI was accompanied by a reduction of the number of sample plots to This led to an extension of the original 1 km-grid to a grid with a mesh size of 1.4 km. To compensate for this reduction, aerial photos were used increasingly. Distribution of the approximately 6500 sample plots. The results of the aerial photo interpretation, as well as the aerial photographs, are stored centrally. The aerial photo interpretation is an important tool for the NFI and, as such, indispensable.. Aerial photo interpreter at work. The aerial model can be seen stereoscopically with the help of special glasses. Aerial photo with a square sampling area and forest boundary lines.

4 Information from the forest first hand After the aerial photo interpretation, three groups of two visit all forest sample plots. Starting with the fourth inventory, this now takes place over a period of nine years. In the process, a different ninth of the sample grid is surveyed every year. The sample plots are chosen to be evenly distributed throughout Switzerland annually. Thus, representative results can be provided in case of extreme events in the same year. The field teams measure and describe the community of trees and assess the habitat on each sample plot. This is hard work since they have to survey about 300 attributes per sample plot. What the teams are not able to learn on the spot, such as the circumstances of ownership or information about logging, they find out from the appropriate forest officials. All this data is recorded with a field computer. The center of each sample plot is surveyed with points in the terrain and a GPS. On average 12 trees are measured per sample plot. Field worker measuring the diameter at breast height of a sample tree. In young growths, the height of plants and the damage caused by browsing is measured.

5 The NFI responds to customer requests All of the NFI s inventory data is stored, analyzed and prepared at the WSL in such a way that it is of use to the public, economy, politics and science. The most important results of the inventories are available as books in German and French. The website also gives you a wealth of information. The forest area is growing The forest area of Switzerland grows by 0.3 % every year. The upper illustration shows the increase of the forest area over the 28 years between the first and fourth NFI. The increase is small in the Plateau and large in the Alps and Southern Alps. The fraction of the area that was maintained in the last 20 years is shown below. It is large in the Plateau and Jura and small in the Alps and Southern Alps % Jura + 0.5% Plateau + 6.4% Pre-Alps % Alps % Southern Alps + 9.7% Switzerland Forest resources: Change in forest area between 1983/85 and 2009/13. Results of the NFI News about the NFI Furthermore, the WSL prepares analyses and extracts of data for specific questions. To date, the employees of the NFI have responded to over 400 larger requests and assisted with projects in practice and research. Please consult our webpage auswertung-en.php about making your own request. You can also contact Urs-Beat Brändli (phone , urs-beat.braendli@wsl.ch) or Fabrizio Cioldi (phone , fabrizio.cioldi@wsl.ch). 78% Jura 89% Plateau 68% Pre-Alps 42% Alps 17% Southern Alps 59% Switzerland Forest management: Fraction of forest area where a treatment has taken place in the last 20 years.

6 Further results of the fourth NFI Timber stock increased over the last 7 years by 1.5 % since the third NFI. For a sustainable wood supply the fraction of stands between 1 and 60 years is too small. 85 % of the net increment of wood was used. Damage to forest by people looking for recreation has increased. Damage to the endangered silver fir intensified due to browsing. Damage to trees due to timber harvest was considerably reduced. Dead wood, which is an important habitat for many animals and fungi, has increased, partly because of the storm «Lothar» by 80 %. Nowadays, more than 90 % of mature timber is established by natural seeding a peak value in Europe. Diversity of woody species did not change, whereas the fraction of broadleaves increased. In the protection forest the situation concerning stability and regeneration of the stands has improved further. The protection forest became denser and stands with insufficient protective effect decreased. Publications of the national forest inventory The publications below can be ordered for the price of postage. Ordering address: WSL Shop, Zürcherstrasse 111, CH-8903 Birmensdorf, Schweizerisches Landesforstinventar. Ergebnisse der dritten Erhebung Brändli, U.-B. (Red.), 2010, ISBN Schweizerisches Landesforstinventar. Ergebnisse der Zweitaufnahme Brassel, P., Brändli, U.-B. (Red.), 1999, ISBN Schweizerisches Landesforstinventar. Ergebnisse der Erstaufnahme EAFV (Hrsg.), 1988, ISSN m 3 /ha Jura 16.0 m 3 /ha Plateau 34.6 m 3 /ha Pre-Alps 28.7 m 3 /ha Alps 18.9 m 3 /ha Southern Alps 23.9 m 3 /ha Switzerland Biodiversity: Timber volume of standing and lying dead trees per hectar. Dead wood is the habitat of many species in the forest. Swiss National Forest Inventory: Methods and Models of the Second Assessment. Brassel, P., Lischke, H. (Red.), 1999, ISBN This publication is also available as a download from: publikationen/publ/methoden-en.php A more extensive list of NFI publications can be found at: