Research methods

The research methods for monitoring the natural forest reserves were developed from 2006 to 2008. They are a combination of tried-and-tested monitoring methods.

This combination consists of the methods formerly applied in the ETH reserves, methods in use in the growth and yield research of the WSL, survey methods of the National Forest Inventory, elements from similar programmes in Central Europe and new developments in the field of habitat structures.

In reserves it is important to differentiate between intensive and extensive monitoring:

  • An intensive monitoring allows statements to be made to the development of forest structure and habitats in 15 natural forest reserves. These can be considered case studies. The statements should be representative for every case study.
  • An extensive monitoring in further 34 reserves allows an assessment to what extent the results from the intensive monitoring in the case studies can be generalized. To this end, data from reserves with similar sites and with intensive and extensive monitoring are compared. Representative statements to individual reserves are not possible with the extensive monitoring because the number of 20-40 sampling plots per reserve is insufficient.

The monitoring is built up on the following modules:

  • Module basic information: information about site, geology, climate and forest history.
  • Module forest and habitat structures: the goal is to understand and interpret the natural forest development in Swiss natural forest reserves in regard to a) their value as a habitat for organisms, and b) their closeness to nature in comparison to managed forests and virgin forests. The monitoring is implemented in permanent plots (0.25-3.0 ha) together with a sample inventory (approx. 100 samples per reserve in the intensive monitoring, 30 in reserves with extensive monitoring, see figure). The sample inventory is based on the methods of the third National Forest Inventory. Lying deadwood is recorded along line transects. Habitat structures such as dead crown wood, stem breaks, shakes, splits, holes in the stem and bracket fungi on standing trees as well as root plates are also recorded.
  • Module photo series: The forest structure is visualized using repeat photographs for documentation and extension. Approximately 10 photo series are taken in each reserve with intensive monitoring and 3 in those with extensive monitoring.
  • Module incidence documentation: diary of noteworthy incidences based on information from the local forest service.
  • Additional modules (not defined yet): extended basic documentation, tree age, LIDAR/aerial photography, diversity of species of xylobiont insects and fungi as well as birds.