Assessing water storage capacity and wettability of plants and woody fragments in post-fire environments: A case study in Los Guájares, SE Spain

Abstract

Wildfires pose significant threats to ecosystems, impacting soil properties and hydrological dynamics. This study investigates the water storage capacity and wettability of ecosystem elements, especially plants and woody fragments in post-fire areas of Los Guájares (Granada, SE Spain). Wildfires alter soil acidity, water storage, and nutrient concentration, affecting the hydrological properties of the forest floor. Understanding the water cycle is crucial for preserving and harnessing ecosystem capabilities. Plant wettability, a key parameter reflecting the ability to retain water on surfaces, is integral to the hydrological and ecological functioning of ecosystems. This research employs contact angle measurements and water storage capacity assessments to explore the relationship between leaves and wood wettability in areas affected by last year's fire (B) compared to adjacent unburned areas (U). The research was conducted in Los Guájares, characterized by steep slopes and Mediterranean climate, and utilized photography and angle measurements in graphic software for the wetting contact angle measurements and a weighing method for the plant surface water storage determination. Results reveal that average water capacity (S) decreases with increasing contact angle (CA) on both burned and unburned surfaces. Woody fragments, such as dry but unburned mango branches, exhibit the highest water capacity after 24 h of water immersion (S24), 1.10 [g^-1] of water, emphasizing the role of dead wood as a water reservoir. Burnt pine wood and fresh mango branches show lower water retention, indicating the impact of fire on water storage. Findings suggest that while the water capacity of leaves in new plants is similar between burned and unburned areas, wettability differs. This research provides insights into species selection for landscape conservation, informs hillslope restoration planning, and identifies areas resilient to droughts.