Responses of Understory Vegetation on Highly Erosive Louisiana Soils to Prescribed Burning in May

Abstract

Prescribed burning is necessary to restore the herbaceous plant community normally associated with the fire-dependent longleaf pine, Pinus palustris Mill., ecosystem. Usually these burns are done in the winter months. However, burning during the early growing season may allow herbaceous plants to recover better than when burning is conducted during the winter months. It was hoped that the additional herbaceous growth would decrease soil movement, a problem on highly erodible hilltop glades of Kisatchie soil (Typic Hapludalfs). The effects of a May burn on soil movement and vegetation growing on two hilltop glades were monitored through one growing season. A prescribed burn on May 24,1994, reduced vegetation and litter cover on the soil surface and the number of woody plants in the understory. This treatment also adversely affected the richness of woody plants within the herbaceous layer and initially reduced the herbaceous standing crop compared to preburn conditions. Soil movement doubled after the May burn; but in another study, a November burn had a similar effect on soil losses. Because the May burn adversely affected woody plants while maintaining the herbaceous plant community, this treatment may be preferable to winter burning on steep, highly erodible Kisatchie soils.

Restoring longleaf pine wiregrass ecosystems:

“…Although growing-season ®re universally depressed forb cover in 1995 to <4%, forbs rapidly recovered during the next growing season, reaching levels as high as 15 and 20%. This dynamic trend generally concurs with other studies, which document an initial decrease in forbs immediately after prescribed ®re (Haywood et al, 1995) followed by increases over time (Moore et al, 1982;Brockway and Lewis, 1997). Forbs are widely reported to bene®t from recurrent ®re in southern pine ecosystems (Hilmon and Hughes, 1965;Wright and Bailey, 1982;Lewis et al, 1988;Platt et al, 1988b;Abrahamson and Hartnett, 1990;Waldrop et al, 1992).…”

“…This result concurs with reports concerning the relatively minor effects of a single ®re event in sandhills and similar environments (Abrahamson and Abrahamson, 1996a, b;Liu et al, 1997). Prescribed ®re also caused a widespread decrease in shrub and woody plant cover, similar to that reported in previous studies (Moore et al, 1982;Abrahamson and Hartnett, 1990;Haywood et al, 1995;Brockway and Lewis, 1997). However, the rapid recovery of these woody components indicates that the overall effect of ®re by itself was ephemeral.…”

Management of Longleaf Pine Woodlands for Threatened and Endangered Species

“…comm., 1995). Prescribed burns in Louisiana in both November and May led to soil movement rates that were twice that seen on unburned control sites (Haywood, Martin, and Novosad 1995). The recommendation to burn vegetation on highly erodible soils or sloped lands must be balanced with evidence that such burns may lead to erosion and sedimentation of lower areas such as gullies.…”

“…On military installations, frequent fires continued to occur throughout the year in artillery impact areas, with occasional accidental or prescribed fires in other areas. Fire may increase soil erosion in the short term (through removal of vegetation and through the use of fire control plowlines), but it restores conditions for the herbaceous plant species associated with high-quality longleaf pine communities (Haywood, Martin, and Novosad 1995). Today's DoD installation managers must therefore balance the need to control erosion with the need to sustain fire-dependent communities.…”

“…(1) in Florida, lightning fires are most common in early summer, and the largest land area is burned naturally during late spring and early summer, (2) studies suggest that early growing-season burns are more favorable to growth and survival of longleaf pine seedlings and saplings than late growing season burns, which may be because they help reduce infection rate of brown spot needle blight (Scirrhia acicola) (a fungus that affects the seedlings during the grass stage), (3) early growing season fires are more detrimental to hardwoods, which compete with pines for establishment (reviewed in Robbins and Myers 1992), and (4) growing season burns may cause less soil loss than winter burning, since rapid recovery of vegetation is possible, and nutrients released by the fire may be quickly incorporated into growing plant tissues (Haywood, Martin, and Novosad 1995). Braswell (1994a, 1994b) suggested that burns be conducted primarily, but not exclusively, between May and July at Marine Corps Base (MCB) Camp Lejeune, NC.…”