|
As long as there have been forests, there have been forest fires, from the bushfires of the Australian outback, across Africa, Asia, and Europe, to the Americas. Whether or not climate change will lead to increased frequency of such fires is a moot point, but understanding the effects of fire on soils could be down to near-infrared reflectance spectroscopy, according to Spanish researchers. César Guerrero, Jorge Mataix-Solera, Victoria Arcenegui, Jorge Mataix-Beneyto, and Ignacio Gómez of the Miguel Hernández University in Elche, Spain, reasoned that NIR could be used to determine a key parameter of fire-damaged soil - the maximum temperature reached (MTR) of the soil. The NIR spectra change significantly depending on the MTR, as organic content is essentially mineralized by the blaze. So, the team carried out calibration experiments on five different soil samples to obtain the characteristic NIR for known MTRs of the fires that had affected them. The researchers point out that some of these changes are not exclusive to the soil type studied, allowing the development of local and global models. With this calibration in hand, the team used partial least squares analysis and obtained appropriate root mean square error of cross validation, root mean square error of the estimation, and residual predictive deviation values. They were then able to verify that thermally sensitive materials are present in soils that will allow future monitoring of fires after they have burned their course. While there is evidence that forest fires have a regenerative impact on the long-term health of a forest, fire can also have a significant detrimental effect on a region. Fire can seriously affect the hydraulic properties of soil causing water runoff rather than absorption and soil erosion. An estimation of the intensity of a fire, based on MTR obtained using NIR spectroscopy, could provide ecologists and environmental scientists with useful information on remediating a site that has been damaged by unusual wildfires that deviates considerably from the normal forest fire cycles. "NIR spectroscopy opens new perspectives on studies of fire effects on soils, taking into account that generally the MTR data are not available with sufficient accuracy and precision for soils affected by wildfire," Guerrero says.
|
|
