Effectiveness of three post‐fire rehabilitation treatments in the Colorado Front Range

Abstract

Abstract:Post-fire rehabilitation treatments are commonly implemented after high-severity wildfires, but few data are available about the efficacy of these treatments. This study assessed post-fire erosion rates and the effectiveness of seeding, straw mulching, and contour felling in reducing erosion after a June 2000 wildfire northwest of Loveland, Colorado. Site characteristics and sediment yields were measured on 12 burned and untreated control plots and 22 burned and treated plots from 2000 to 2003. The size of the hillslope plots ranged from 0Ð015 to 0Ð86 ha.Sediment yields varied significantly by treatment and were most closely correlated with the amount of ground cover. On the control plots the mean sediment yield declined from 6-10 Mg ha 1 in the first two years after burning to 1Ð2 Mg ha 1 in 2002 and 0Ð7 Mg ha 1 in 2003. Natural regrowth caused the amount of ground cover on the control plots to increase progressively from 33% in fall 2000 to 88% in fall 2003. Seeding had no effect on either the amount of ground cover or sediment yields. Mulching reduced sediment yields by at least 95% relative to the control plots in 2001, 2002, and 2003, and the lower sediment yields are attributed to an immediate increase in the amount of ground cover in the mulched plots. The contour-felling treatments varied considerably in the quality of installation, and sediment storage capacities ranged from 7 to 32 m 3 ha 1 . The initial contour-felling treatment did not reduce sediment yields when subjected to a very large storm event, but sediment yields were significantly reduced by a contour-felling treatment installed after this large storm. The results indicate that contour felling may be able to store much of the sediment generated in an average year, but will not reduce sediment yields from larger storms.

Wildland fire in ecosystems: effects of fire on soils and water

“…Seeded species are expected to be of greatest value during the second and third rainy seasons (Esplin and Shackleford 1978), when plant litter produced by the first year's growth covers the soil. However, after the Bobcat Fire in the Colorado Front Range, Wagenbrenner (2003) found that seeding had no significant effect on sediment yields at the hillslope scale in either the first or second years. In addition, seeding had no significant effect on percent of vegetative cover compared to untreated areas (Wagenbrenner 2003).…”

Reduction of nutrient losses with eroded sediments by post-fire soil stabilisation techniques

“…Therefore, post-fire soil stabilisation techniques (e.g. seeding and mulching) must be applied as soon as possible to accelerate development of ground and vegetation cover, reduce surface runoff and prevent soil erosion (Pinaya et al 2000;Robichaud et al 2000;Vega et al 2005;Wagenbrenner et al 2006;Robichaud 2009;Fernandez et al 2011Fernandez et al , 2012. In many countries, seeding of fast-growing non-native grass species is the most common post-fire stabilisation technique to rapidly increase plant cover because of its relatively low cost and easy aircraft application (Robichaud et al 2000;Beyers 2004).…”

“…However, this practice has been questioned because it can introduce exotic species (Kruse et al 2004) and displace native species, interfering with natural vegetation recovery (Beyers 2004). Furthermore, grass seeding could be ineffective in increasing ground cover or reducing erosion rates during the first critical rain events after a fire (Robichaud et al 2006;Wagenbrenner et al 2006;Groen and Woods 2008;Peppin et al 2010;Fernandez et al 2012). As an alternative, straw mulch is increasingly being applied to burnt areas with high value due to its immediate effectiveness in increasing ground cover and erosion control (Bautista et al 2009;Robichaud et al 2010).…”

Effects of post-fire soil stabilisation techniques on trace elements lost by erosion

“…Range of estimated concentration (mg kg 21 DW) and accumulated mass (g ha 21 ) of trace elements in eroded sediments of the present study compared with reference levels (mg kg 21 DW) A Estrada values estimated considering that 5% of total soil nutrient was removed by DTPA and EDTA extractants (Chen et al 1996;Fernández-Calviño et al 2012); DEC, European Union limit for concentrations of heavy metals in soil receiving sewage sludge application (CEC 1986) study (Díaz-Raviña et al 2012), the reduction of erosion rates with straw mulching (73-94%) was twice that with herbaceous seeding (34-42%) during the first 4 months after application. However, mulch effectiveness depends on strand length, ground cover amount, thickness of application and longevity (Bautista et al 1996;Wagenbrenner et al 2006;Groen and Woods 2008;Robichaud et al 2010;Fernández et al 2011;Robichaud et al 2013aRobichaud et al , 2013b.…”

“…seeding and mulching) of soils must be applied as soon as possible after the wildfire to accelerate development of ground and vegetation cover and to reduce surface runoff and prevent soil erosion (Pinaya et al 2000;Robichaud et al 2000;Vega et al 2005;Wagenbrenner et al 2006;Groen and Woods 2008;Robichaud 2009;Fernández et al 2011. Despite its undoubted interest, few studies deal with the effects of fire on soil nutrient losses by erosion (DeBano et al 1998;Gabet et al 2005;Robichaud et al 2006;Spigel and Robichaud 2007) and their reduction by post-fire stabilisation techniques (Thomas et al 2000;Robichaud et al 2006;Gómez-Rey et al 2013).…”