Long-term effects of fire and three firefighting chemicals on a soil - plant system

Abstract

The impacts of fire and fire-fighting chemicals (FFC) on soil properties and the soil-plant system were evaluated five years after treatment application. Unburnt soils (US) were compared with burnt soils treated with water alone (BS) or with foaming agent (BS+Fo), Firesorb polymer (BS+Fi), or ammonium polyphosphate (BS+Ap). Soils (0-2 cm depth) and foliar material (Ulex micranthus, Pterospartum tridentatum, Erica umbellata and Pinus pinaster) were analysed for total-C, total-N, δ BS+Ap than in other treatments, while the opposite was observed for Erica; shrubs were always taller in BS+Ap. After 3 years of growth, the size of pine seedlings followed the order BS+Ap > US > other treatments.Foliar N and P, scrub regeneration and growth of pines showed the long-term fertilizing effect of ammonium polyphosphate, although the second highest pine mortality was found in the BS+Ap treatment. The foaming agent did not affect vegetation cover, and Firesorb had no noticeable effect on shrubs but the highest pine mortality.

Effects of fire and three fire-fighting chemicals on main soil properties, plant nutrient content and vegetation growth and cover after 10 years

“…These authors set up the so-called 'Tomiño experiment' in a medium size experimental area (1000 m 2 ) on a NW Spain shrubland, where they applied three FFCs (foaming agent RFC-88, acrylic acid-acrylamide terpolymer Firesorb and ammonium polyphosphate FR Cros 134 P) immediately after a prescribed fire. Their results showed an increase in available N and P, which was especially strong and long-lasting in the ammonium polyphosphate treatment; a factor that could delay vegetation recovery in these plots (Couto-Vázquez and González-Prieto, 2006;Couto-Vázquez et al, 2011). Five years after the fire, shrub cover and height, as well as pine size and mortality, were affected by the ammonium polyphosphate and to a lesser extent by the terpolymer (Couto-Vázquez et al, 2011).…”

“…Their results showed an increase in available N and P, which was especially strong and long-lasting in the ammonium polyphosphate treatment; a factor that could delay vegetation recovery in these plots (Couto-Vázquez and González-Prieto, 2006;Couto-Vázquez et al, 2011). Five years after the fire, shrub cover and height, as well as pine size and mortality, were affected by the ammonium polyphosphate and to a lesser extent by the terpolymer (Couto-Vázquez et al, 2011). Changes in the microbial community structure were also detected five years after the prescribed fire, being more noticeable in the terpolymer and the ammonium polyphosphate plots (Barreiro et al, 2010).…”

“…Although longer-term studies would be better to assess the consequences of FFC application on vegetation (Giménez et al, 2004;Couto-Vázquez et al, 2011), some studies already available show that some plant communities are affected in different ways by FFCs in the short-term. Larson and Duncan (1982) studied the effects of application of diammonium phosphate (DAP) as a fire retardant on burnt and unburnt grassland areas in California.…”

“…Consequently, there are three possible scenarios under realistic wildfire-fighting conditions: (1) the retardant reaches soils in the fire line and both soil and retardant are affected by the heating and oxidation caused by the fire; (2) the retardant reaches soils in the burnt area which are still hot or warm; and (3) the retardant reaches soils close to the fire line but not affected by the fire. Most studies are focused on the last two scenarios, probably due to the problems derived from studying the narrow and very heterogeneous area of the first scenario (Couto-Vázquez et al, 2011).…”

“…Up to now, the most comprehensive field experiment on the longterm influence of FFCs on terrestrial ecosystems assessed throughout five years the effects of fire and FFCs on soils (chemical, biochemical and microbial properties) and plants (size, coverage and nutrient content of dominant species) (Couto-Vázquez and González-Prieto, 2006;García-Marco and González-Prieto, 2008;Barreiro et al, 2010;Couto-Vázquez et al, 2011). These authors set up the so-called 'Tomiño experiment' in a medium size experimental area (1000 m 2 ) on a NW Spain shrubland, where they applied three FFCs (foaming agent RFC-88, acrylic acid-acrylamide terpolymer Firesorb and ammonium polyphosphate FR Cros 134 P) immediately after a prescribed fire.…”