Effects of the Severity of Wildfires on Some Physical-Chemical Soil Properties in a Humid Montane Scrublands Ecosystem in Southern Ecuador

Abstract

Humid montane scrublands (HMs) represent one of the least studied ecosystems in Ecuador, which in the last decade have been seriously threatened by the increase in wildfires. Our main objective was to evaluate the effects of wildfire severity on physicochemical soil properties in the HMs of southern Ecuador. For this purpose, fire severity was measured using the Normalized Burn Ratio (NBR) and the difference between pre-fire and post-fire (NBR Pre-fire-NBR Post-fire) over three contrasted periods (years 2019, 2017, and 2015) was determined. Likewise, 72 soil samples from burned HMs and 72 soil samples from unburned HMs were collected at a depth of 0 to 10 cm, and some physical (bulk density and texture) and biochemical (pH, soil organic matter, and total nutrients) soil properties were analyzed and statistically processed by one-way ANOVA and principal component analysis (PCA). Results indicate that burned HMs showed mixed-severity burning patterns and that in the most recent wildfires that are of high severity, SOM, N, P, Cu, and Zn contents decreased drastically (PCA: component 1); in addition, there was an increase in soil compaction (PCA: component 2). However, in older wildfires, total SOM, N, P, K, and soil pH content increases with time compared even to HMs that never burned (p-value < 0.05). These results can help decision makers in the design of policies, regulations, and proposals for the environmental restoration of HMs in southern Ecuador affected by wildfires.

Indigenous use of fire in the paramo ecosystem of southern Ecuador: a case study using remote sensing methods and ancestral knowledge of the Kichwa Saraguro people

“…The seasonality of fires that we documented during the 4 years contrasted (Fig. 4 ) is consistent with other studies in which many fires have been reported to be human-caused (Rother et al 2020 ; Carrión-Paladines et al 2022 ). However, in our study area due to the lack of information based on historical accounts (Crawford and Brueckheimer 2012 ) and limited fire records, we estimate that most of these events have an interannual occurrence trend.…”

“…The seasonality of fires that we documented during the 4 years contrasted (Fig. 4) is consistent with other studies in which many fires have been reported to be humancaused (Rother et al 2020;Carrión-Paladines et al 2022).…”

“…The fire weather was determined using NASA meteorological data ( https://power.larc.nasa.gov/data-access-viewer/ accessed on February 5, 2022) corresponding to temperature (°C), precipitation (mm), relative humidity (%), and wind speed (m/s converted to km/h) (Rodrigues and Braga 2021 ; Carrión-Paladines et al 2022 ). The meteorological data were generated considering the paramo zone whose geographical coordinates are −3.727639° and −79.205111°.…”

“…Finally, by 2021, lowseverity fires occurred in only 9% of the burned parish territory with 80% of low post-fire vegetation growth. In this context, traditional fire use directly influences the generation of this type of fire, possibly as a function of climatic conditions, fuel content, and human reasons for burning that have been reported in some recent research (e.g., Carrión-Paladines et al 2022).…”

Biological Crust Diversity Related to Elevation and Soil Properties at Local Scale in a Montane Scrub of Ecuador

“…and pine ( Pinus radiata D. Don) plantations [ 4 , 5 , 6 ]. In addition, they face constant threats due to anthropogenic wildfires, which produce high and low severity fires, and the subsequent loss of soil quality due to erosion processes [ 7 ]. Despite being a highly anthropized ecosystem, the EMSs play an important role in the management of the micro-watersheds that supply drinking water to populations within Ecuador [ 8 ].…”