Changing fire regimes due to WUI growth in Mediterranean landscapes

Posted 08/23/23

The growing impact of humans on natural landscapes and climate change imposes a lot of pressure on natural landscapes, biodiversity, and ecosystem functionality. Expanding low-density settlements near wildland vegetation have been observed across the globe and are a focal point for wildfire hazard risks. Kira Pfoch is working on assessing the rate and extent of the Wildland-Urban Interface growth with Landsat imagery and changing patterns of wildfire activity in these regions.

Human activity is recognized as a major driver of changes in land cover, land use, and fire regimes that influence and disrupt ecosystems. The Wildland-Urban Interface (WUI) defines areas where low-density settlements overlap with high amounts of wildland vegetation cover and are a focal point for wildfire hazard risks. WUI land uses are expanding and cause many biotic and abiotic implications for the environment and ecosystem functionality, such as declining biodiversity, loss, and fragmentation of habitat. Therefore, we require spatial and temporal information to investigate the rate and extent of the WUI growth and assess its structure and composition for preventing wildfire hazard risk and monitoring its impacts on ecosystems.

Point-based WUI maps for South Australia, California (Carlson et al 2022), and Portugal. WUI reference datasets: Australia: Microsoft Building Footprint (~2018) & DEA Land Cover 2018, California: Microsoft Building Footprint (~2015) & NLCD (2016), Portugal: Microsoft Building Footprint (2014-2021) & COS Land Cover (2018).
Point-based WUI maps for South Australia, California (Carlson et al 2022), and Portugal. WUI reference datasets: Australia: Microsoft Building Footprint (~2018) & DEA Land Cover 2018, California: Microsoft Building Footprint (~2015) & NLCD (2016), Portugal: Microsoft Building Footprint (2014-2021) & COS Land Cover (2018).

Especially in the Mediterranean-climate biome, fire has an important ecological role, which put humans living within the Wildland-Urban Interface at high risk, and fire hazards in these regions have achieved media attention in recent years. Mapping the WUI is essential to quantify the extent of this increasing settlement in wildland vegetation-dominated areas. Standard land cover maps often do not include this widespread settlement type, while differentiating only either into high-density urban land uses or vegetation cover.

So far, the extent of the Wildland-Urban Interface and its growth has only been mapped for a few countries or regions based on national land cover products and census or build-location datasets. However, these datasets are only limited available, and therefore, limit our ability to consistently capture WUI area growth, its structures, and drivers.

Wildfire in the close proximity of Adelaide (Australia) in 2020 (Landsat-8 from 2nd January 2020, RGB-vizualization: NIR-RED-GREEN, source USGS)
Wildfire in the close proximity of Adelaide (Australia) in 2020 (Landsat-8 from 2nd January 2020, RGB-vizualization: NIR-RED-GREEN, source USGS)

Kira Pfoch is conducting a study aiming at filling this gap in data availability. Kira’s main objective is to map WUI growth within the Mediterranean-climate biome with the Landsat Archive. She investigates reasons for WUI growth that is likely to be associated with expanding human activities that lead to increasing settlements in natural landscapes. Kira further investigates the relation between WUI growth and changes in wildfire activities and characteristics, to assess whether increasing human influences affect fire activity within these landscapes. Finally, the impact and interaction of human activity, climate change, and wildfires affect the natural vegetation, and therefore, Kira studies vegetation type conversion concerning WUI growth across different regions within the Mediterranean climate biome.
In conclusion, Kira’s research will help determine to identify growing human-environment conflict and its impacts on fire and vegetation.

Wildfire activity in Portugal in 2017 ((left image) pre-fire image 10th July 2017, (right image) fire image from the 26th July 2017, source USGS)
Wildfire activity in Portugal in 2017 ((left image) pre-fire image 10th July 2017, (right image) fire image from the 26th July 2017, source USGS)

Story by Pfoch, Kira