The expansion is the same as that recorded ten years ago in the previous forest inventory conducted jointly by the department and the WSL federal forest, snow and countryside research institute.
However, logging in the Jura Mountains and the plateau — the area between the Jura and the Alps — has reduced the volume of standing timber in those areas, the report said.
The amount of spruce, a staple of the Swiss forest industry, has dropped on the plateau by nine percent in the past seven years, according to the figures.
Meantime, stocks of hardwoods have increased, the report said.
And the volume of wood in the country’s more protected Alpine areas also continues to grow.
The report said the ecological richness of forests in the Alps is better than elsewhere because of the growing quantity of dead wood in these areas.
Begun in 1985, the Swiss forest inventory is conducted every 10 years, based on surveys of 6,500 different areas of the country.
The latest results are based on data from 3,700 sites with more complete information to be published next year.