Post-Fire Recovery of Temperate and Mediterranean Ecosystems: An Interplay between Soil, Nutrients and Vegetation

Abstract

Wildfires strongly alter soil properties, inducing ecosystem recovery over extended periods, yet their long-term impacts remain barely known. This study investigated a 14-year post-wildfire chronosequence in Chile’s mediterranean and temperate humid forests, revealing ecosystem-specific mechanisms of soil properties and nutrient recovery. By analysing sites at different secession stages, the chronosequence approach assessed temporal changes and ecosystem recovery, providing critical insights into long-term wildfire effects on soil dynamics and nutrient recovery. Wildfires increased soil bulk density in both systems. Mediterranean soils experienced greater compaction due to organic matter loss, soil aggregate destruction, ash-induced pore clogging, and accelerated erosion resulting in denser subsoils. Soil texture shifts was dependent on ecosystem: in mediterranean soils - clay and silt increased through ash redistribution and aggregation, while temperate soils became sandier due to thermal disaggregation and topsoil erosion. While vegetation recovers quickly, soil properties like bulk density take over 14-years to return to pre-fire conditions.In humid temperate forests, ash input initially increased soil pH (4.8–5.8), reducing acidity and potentially mitigating aluminium toxicity, while raising nutrient availability. Base cation saturation increased in mediterranean woodlands benefiting from ash retention and reduced leaching (lower rainfall) and ash infiltration into subsoil. Humid temperate forests, however, recovered slowly due to high rainfall, leaching of basic cations, and their low stocks in acidic subsoils and parent material. Carbon and N losses were restricted to the litter horizon in temperate forests, recovering quickly via fire-resistant tree input, whereas mediterranean soils suffered severe C and N depletion due to complete vegetation loss, erosion, and probable low N fixation.           Fire effects and recovery trajectories are ecosystem-specific, shaped by landscape, geology, hydrology, nutrient stocks, and vegetation resilience. Wildfires alter biogeochemical cycling, but current datasets remain insufficient for Earth-system models. Understanding fire frequency and severity is critical for improving ecosystem projections in fire-prone regions globally.

Keywords: Historical Fire, Wildfire, Nutrients stocks, Ecosystem recovery, Losses of nutrients, Vegetation succession, Chronosequence approach