RUNOFF AND SEDIMENT PRODUCTION FROM BURNED FOREST SITES IN THE GEORGIA PIEDMONT¹

Abstract

Runoff and sediment production was measured under simulated and natural rain from 1x5 m plots established on a cutover and burned mixed pine-hardwood site in the Georgia Piedmont. Trees on the study site were cut and removed without mechanical disturbance. Slash was removed, kiln dried and replaced on the slope, and burned prior to plot installation. Three slopes, two rainfall intensities, three rainfall simulations representing three soil moisture conditions, and two replicate plots were used. The experiment was repeated four times during the period July 1989-July 1990 to investigate the effects of temporal changes in surface conditions and particularly root mat and residual forest floor decemposition. Runoff and sediment production from natural rainfall events was also measured from these plots during the period February-October 1990. Results of all measurements indicate that runoff and sediment production were generally low because of the protection afforded by the residual forest floor following burning. However, temporary hydrophobic conditions caused by a dry organic layer produced relatively high runoff rates and high sediment for the first few minutes of runoff for some of the simulated rainfall applications. (KEY TERMS: runoff; sediment production; hydrophobicity; burning; Georgia Piedmont.)

Post‐fire runoff and erosion from simulated rainfall on small plots, Colorado Front Range

“…It seems that the small differences in runoff with burn severity in our study are due primarily to the high runoff rates from our unburned and low-severity sites relative to other researchers (e.g. Shahlaee et al, 1991).…”

“…The lack of any water repellency in the high-severity sites in the Hourglass fire can be attributed to the fact that the antecedent soil moisture content was more than 20% (Table II). Other studies have shown that natural and fire-induced hydrophobicity is not present at such high soil moisture levels, making the soils much more wettable than under dry conditions (Shahlaee et al, 1991;Doerr and Thomas, 2000;Huffman et al, 2001). The high soil moisture content and corresponding lack of water repellency is probably why the two high-severity plots in the Hourglass fire had a mean runoff ratio of only 36% (Table III).…”

“…In the southeastern USA, simulated rainfall rates of 130 mm h 1 produced 65 g m 2 from small plots (Shahlaee et al, 1991), and Robichaud and Waldrup (1994) measured sediment yields of 139 g m 2 as a result of applying 100 mm h 1 of simulated rainfall for 30 min on plots burned at high severity. Given the shorter simulation period used by Robichaud and Waldrup (1994), the latter value is actually quite comparable to our measured sediment yields.…”

Post‐fire runoff and erosion from rainfall simulation: contrasting forests with shrublands and grasslands

“…In previous studies, water repellency was associated with a sharp initial spike in runoff rate with decreasing runoff rates thereafter (Shahlaee et al, 1991;Hester et al, 1997;Robichaud, 2000). These decreasing runoff rates were attributed to increases in infiltration as the soil became saturated, which has the effect of decreasing the degree of water repellency (DeBano, 1981).…”

Prescribed Burning and Erosion Potential in Mixed Hardwood Forests of Southern Illinois

“…Most of the research on prescribed fires and their impact on sediment loss have been carried out in pine dominated forests, and not enough studies are available in mixed hardwood forests. Plot scale erosion studies of mixed hardwoods forests in Georgia reported that sediment loads per 30-min simulated rainfall ranged from 6 kg·ha −1 to 379 kg·ha −1 [52]. It was concluded that sediment production was low because residual root cover was not completely burned and high infiltration rates were measured in erosion plots.…”