Why are wildfires in the Karst Plateau a growing problem?
The Karst Plateau is a sensitive landscape. It is rocky, often dry, and covered with many types of vegetation. Forests, shrubs, grasslands and abandoned fields often lie very close to one another. In dry weather, this mixture can burn very easily. Overgrowth adds to the risk. In the past, many open areas were used for farming or grazing. Today, some of these areas are no longer cared for in the same way. Shrubs and young trees spread quickly, giving fire more material to burn. A wildfire is therefore not caused only by one spark or one hot day. The risk also grows because of dry weather, climate change and changes in land use.
In the cross-border Karst area, fires are becoming more common, larger and more damaging. Large wildfires also affect people who do not live next to the forest. Smoke can worsen the air, roads can close, and water, soil, plants and animals can be harmed. A fire can change a place for many years.
What can satellites show us?
Satellites can help us to look at large areas from above. This is very useful in the Karst, because wildfires do not stop at municipal or national borders. A fire can spread across Slovenia and Italy, so the whole area has to be studied together.
In this study, the area included the municipalities of Miren-Kostanjevica, Komen and Duino-Aurisina. For newer wildfires, researchers used satellite images from the European Sentinel-2 satellites that are part of the Copernicus programme, which observes the Earth. Sentinel-2 does not only take normal colour photos. It also records light that human eyes cannot see, such as near-infrared light. This helps show how healthy plants are and where the land has burned. The satellites can take images of the same place many times. Because of this, we can compare the land before a wildfire, just after it and later during recovery and enable the researcher to observe how large the burned area was and how the surface changes over time.
How do satellite images tell us where the fire was?
Researchers do not only look for burned patches on an image. They use calculations, called indices, that compare different types of light recorded by the satellite. The idea is simple: healthy plants, burned ground and bare soil reflect light in different ways.
In this study, the BAI and BAIS2 indices helped show burned areas. The NDVI index helped show the condition of plants. NDVI is one of the widely used method to check vegetation from space. Healthy plants reflect a lot of near-infrared light and absorb more red light. Burned or weak vegetation behaves differently.
Because of this, NDVI can show where plants are healthy, where they are stressed and where they are missing. After a wildfire, this is useful not only for finding the burned area, but also for seeing how well plants return later.
How were older wildfires studied?
Sentinel-2 has been working since 2015, so it cannot show wildfires from earlier years. For older wildfires, researchers used the Landsat satellite archive. Landsat is run by NASA and the United States Geological Survey. It has recorded the Earth’s land surface since 1972.
The study first collected wildfire records from Slovenia and Italy. There were 682 records in total. Researchers then chose wildfires from the study area and focused on those that were larger than 0.5 hectares. Very small wildfires are often hard to see clearly in older satellite images. For each wildfire, they searched for a good satellite image from before the wildfire and one from the after. Sometimes clouds, shadows or poor image quality made this hard. In some cases, they had to use another date or combine several images. In the end, they could clearly map the burned areas for 171 wildfires. This gave the researchers a useful cross-border database. It shows where wildfires happened and where the largest burned areas were.
Why are drones also needed?
Satellites are very useful, but they cannot show every small detail. The Karst changes a lot of over very short distances. In just a few metres, there may be rock, meadows, shrubs, a forest edge, bare soil or a doline. Because of this, researchers also used a drone in a pilot area in Miren-Kostanjevica. The drone took very detailed images in May, July and November 2025, and in February 2026. These images were used to make colour maps, vegetation maps, surface models and 3D point clouds. With these images, researchers could follow small changes in vegetation and the ground through the seasons. Drone images are especially useful after a wildfire, because they can show which parts of the land are recovering faster and which parts are still bare or weak.
How does nature recover after a wildfire?
Recovery after a wildfire is not the same everywhere. In the pilot area of Municipality Miren-Kostanjevica, which was affected by biggest wildfires in 2003 and 2022, vegetation came back in patches. Some places recovered faster. Others stayed open and dry for longer. Better recovery was seen near vegetation edges, between meadows and forests, and in small favourable places such as dolines. Dolines often keep more soil and moisture, so vegetation can return more easily there. Open, rocky and dry areas usually recover more slowly. They may have little soil and less shade. In these dry places, vegetation may stay sparse for several years. This is important because people often think a burned area simply becomes green again. In reality, each part of the landscape behaves differently.
What does this mean for local planning?
This kind of research can help people make better decisions. If we know where large wildfires happened before, we can treat these places as more sensitive. If we know where nature recovers slowly, we can plan restoration more carefully. If we know that overgrowth raises wildfire risk, we can plan regular land management. This may include cutting back too many shrubs, keeping some open areas and supporting grazing where it is suitable. In the pilot area, shrubs were cut and land was prepared for grazing before one of the winter surveys. This shows that wildfire prevention is also landscape management. Wildfire safety is not only the work of firefighters, but it also depends on how we care for fields, meadows, forest edges and abandoned land.
Why is cross-border work important?
Karst wildfires are not only Slovenian or Italian. The landscape continues across the border, and so does the fire risk. For this reason, Slovenia and Italy need shared data and similar methods. Both sides must be able to compare wildfire records, satellite images and field observations. This is one of the main values of the KARST FIREWALL 5.0 project. The wildfire database was also prepared through this project. Working together helps municipalities, researchers and land managers understand the same area in the same way. That makes prevention and recovery easier to plan.
Why are GIS maps important?
GIS means geographic information system. In simple words, it is a smart way to connect data with maps. With GIS, many types of information can be placed on the same map: old wildfires, satellite images, drone images, land use, slopes, vegetation and field notes. When these data are viewed together, the picture becomes clearer. GIS helps answer practical questions. Where should the land be watched more closely? Where is the fire risk higher? Where may vegetation need more time to recover? Where would land management help most? For residents, the main message is simple. Satellites, drones and GIS maps are not distant tools used only by scientists. They help us protect the places where we live.
