Background information and definitions
Disturbance can clear dominant plants, maintain light availability and control nutrient levels – and may maintain vegetation in a desirable and/or species-rich state (Hall et al. 2008; Middleton 2013). Therefore, conservationists sometimes want to actively restore disturbance where it has ceased, or maintain disturbance at a site where it would otherwise be lost. Prescribed burns are one way to do this.
Fire itself may be the historic or traditional disturbance that maintains wetlands in a desirable state. Some wetlands, especially ones that dry out in summer, burn naturally every few years (Sutter & Kral 1994). In other wetlands, prescribed burns have been used by humans to manage vegetation (Middleton 2013). Reduced disturbance from fire in these systems – whether through abandonment or deliberate control of fire (e.g. via fire breaks or legislation) – can be detrimental to vegetation diversity, composition and structure (e.g. Clark & Wilson 2001).
Caution: Disturbance, and fire in particular, is not a natural feature of all wetlands. For example, even within the southeast USA, the natural fire frequency can vary from once per year to once per century (Sutter & Kral 1994). It can be difficult to control the intensity, duration and area of prescribed burns. Burns in winter or wet season, might be easier to control than burns in the summer or dry season. Smoke from prescribed burns could be detrimental to human health, especially near urban areas (Agee 1996). Also note potential impacts on animals within wetlands – but that some taxa might be unaffected or be able to avoid fire (e.g. Ditlhogo et al. 1992).
The timing and duration of monitoring might be particularly important when evaluating the effects of this action. Burning might produce apparently desirable changes in vegetation over the short term, followed by a rapid return to a degraded state.
Related actions: Use prescribed fire to control problematic plants, whose success is not linked to a change in disturbance regime; Reduce frequency of prescribed burning; Reduce intensity of prescribed burning; Change season/timing of prescribed burning.
Agee J. (1996) Achieving conservation biology objectives with fire in the Pacific Northwest. Weed Technology, 10, 417–421.
Clark D.L. & Wilson M.V. (2001) Fire, mowing, and hand-removal of woody species in restoring a native wetland prairie in the Willamette Valley of Oregon. Wetlands, 21, 135–144.
Ditlhogo M.K.M., James R., Laurance B.R. & Sutherland W.J. (1992) The effects of conservation management of reed beds. I. The invertebrates." Journal of Applied Ecology, 29, 265–276.
Hall S.J., Lindig-Cisneros R. & Zedler J.B. (2008) Does harvesting sustain plant diversity in Central Mexican wetlands? Wetlands, 28, 776–792.
Middleton B.A. (2013) Rediscovering traditional vegetation management in preserves: trading experiences between cultures and continents. Biological Conservation, 158, 750–760.
Sutter R.D. & Kral R. (1994) The ecology, status, and conservation of two non-alluvial wetland communities in the South Atlantic and Eastern Gulf coastal plain, USA. Biological Conservation, 235–243.