Center for Ecological Research and Forest Practices CREAF collaborates with the Barcelona Provincial Council’s Municipal Technical Office for the Prevention of Forest Fires and Agricultural Development OTPMIFDA to maintain environmental protection strips around urban areas. These strips act as safety corridors against forest fires and help safeguard city centers.
The guide outlines which vegetation should remain in these protection strips, which plants to avoid because they burn easily, which trees to keep or remove based on their traits, and how erosion can be prevented. It also emphasizes a twice yearly cleaning routine to keep the strip free of new growth.
The strip should be a low combustibility zone with a modest shrub layer.
What is an environmental protection strip It is a corridor at least 25 meters wide that surrounds urbanizations and other population centers located near woodlands or within 500 meters. Depending on its purpose, the strip should be non combustible or low combustible and feature a middle shrub layer to slow the spread of flames into the crown, ensuring the safety of people and property in a potential forest fire. Simultaneously, these zones should hinder a fire from an urban area from reaching the surrounding forests and becoming a major wildfire.
The development sequence of a guard strip is described for implementation.
Since 2015 both institutions have worked together to study how lanes opened around homes in urbanizations behave ecologically and how soil erosion can be prevented. A permanent network of test sites has been established across 12 urbanizations in the province of Barcelona to monitor these effects, with CREAF researchers including Josep Maria Espelta examining how the opened areas alter remaining vegetation and soil stability.
Forests now occupy more land than in the past, increasing the wildfire risk in forested areas.
Why are these strips needed Forested areas have expanded, boosting the wildfire hazard for lands near woods. Two factors contribute to this trend: the abandonment of managed crops and forestry due to lower profitability, and urban expansion drawing people to quiet, nature-rich locations. A visual comparison of orthoimages from 1956 and 2018 illustrates these changes in the Collserola region as documented by the ICGC.
Vegetation, pruning and erosion how it is done
Species to retain in these areas should maintain year round foliage with high moisture and possess a compact structure that yields fewer fine residues while reducing fuel load. The strategy also includes checking for the presence of plants that are highly flammable due to essential oils or volatile compounds such as lavender, lavender types, or other steppe and heather species to ensure safe composition of the strip.
Each species responds differently and slow growing species must be identified
Tree density within the strips should be reduced to leave space for slower growth and to prevent the canopy from reestablishing a dense shade. Controlling shrub growth is aided by allowing more light and space. It is important to know which tree species grow more slowly, such as oaks, to maintain the minimal connectivity of plants across the strip.
The growth of these trees may still continue, and after a year or two some trees can reach values that require action again under the regulations. If pruning is not performed with care according to the criteria, the vegetation may exceed thresholds within six months and trigger another operation.
On steep slopes, when fringe vegetation is removed, soil erosion may increase. Evaluations show erosion signs in about eight in ten strips, with moderate erosion in roughly six of ten cases. The most significant losses occur where tree crowns cover less than 35 percent of the ground. Allowing crowns to cover more than half of the land on steep slopes helps reduce erosion, though trees near rivers and edges that threaten land balance should be cut back when necessary.
Reference article: marked citation.
Environment department note