The use of remote sensing methods has a long tradition at NLI which dates back to the 1980s. A significant development in this area was connected with the second cycle of the National Forest Inventory. In 2009, a specialised remote sensing workplace was established at the Frýdek-Místek branch and its professional and processing scope is continuously expanding.
We use multiple data sources to monitor the status and development of forests. These include aerial surveys (LMS) from the national aerial photography organised by the Czech Office for Surveying, Mapping and Cadastre (ČÚZK). Within the European COPERNICUS programme we process satellite imagery from Sentinel satellites (in particular SENTINEL-2 multispectral satellite data), long-term series are analysed from the LANDSAT programme, the latest source used is PlanetScope commercial satellite data with high spatial and temporal resolution.
The applicability of the different methods and data sources depends on the size of the monitored area and the requirement for data timeliness. The advantage of satellite data is the potential for repeated monitoring of large areas (e.g., the whole country) with a short repeat period: annually / several times per growing season / after several days / daily / up to several times per day. The advantage of LMS is its high positional accuracy (mean positional error < 1 m) and high spatial resolution (currently < 20 cm per pixel) with repeated imaging of half of the Czech Republic annually (i.e., full coverage every 2 years). For nationwide survey of forest condition, the optimal approach is a combination of remote sensing and ground measurement, on which, for example, the National Forest Inventory in the Czech Republic is based.
