Remote-sensing module (WBS)

Comparing aerial images, taken at different time periods, is a quick and cost-effective way to quickly detect landscape changes. This allows monitoring all sites of national importance on a regular basis. During the first phase of the project (2012 to 2017), the state of the habitats at the times the inventories were compiled (1980s and 1990s) has been compared. The interpretation is done manually on a 3D screen. The images from the 1980s and 1990s are in black and white, whereas the contemporary images are false color infrared stereo images. To ensure reproducibility of the interpretation and location of changes within the sites, a grid of 50m x 50 m cells was placed over each site. Within each grid cell, simple indicators such as changes in tree and shrub cover or infrastructures such as roads and buildings are recorded using an ordinal scale with 11 classes (1 ≙ <0%, 2 ≙ 1–10%, 3 ≙ 11–20%, 4 ≙ 21–30%, 5 ≙ 31–40%, 6 ≙ 41–50%, 7 ≙ 51–60%, 8 ≙ 61–70%, 9 ≙ 71–80%, 10 ≙ 81–90%, 11 ≙ 91–100% cover). This allows a quick interpretation of changes, e.g., abandonment (by shrub encroachment). The centers of the grid cells correspond to the interpreted points of the Swiss Land-Use and Land-Cover Statistics and the Swiss National Forest Inventory (NFI). Based on these data, an online color-coded warning system has been established to ensure early detection of negative changes and to conduct prompt conservation measures. This tool can be assessed by the responsible federal and cantonal conservation authorities. The very laborious field surveys are conducted in a subsample of all sites. Vegetation changes in fens, bogs, dry grasslands, riparian areas and flood plains are interpreted using diversity and compositional measures. The regular sampling of amphibian species and their population-size classes reflect temporal changes in amphibian breeding sites. In addition, remote-sensing methods are developed to automatically calculate as many features as possible that are important for the quality of habitats of national importance. One example is shrub encroachment, which is calculated from the canopy height models obtained from the 3D aerial image data.

Additional Info

Field	Value
parent	Monitoring the Effectiveness of Habitat Conservation in Switzerland (WBS)