Change season/timing of prescribed burning: freshwater marshes

Overall effectiveness category Unknown effectiveness (limited evidence)
Number of studies: 1
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How is the evidence assessed?

Effectiveness

60%
Certainty

30%
Harms

10%

Calculating overall effectiveness category

Background information and definitions

Prescribed burning could have different effects on vegetation depending on the time of year at which it is done. For example, it might be beneficial to avoid disturbance when certain plants are young/flowering so that they can grow/reproduce and contribute to the community. The season of disturbance can also affect nutrient levels and impacts to soils by trampling or vehicles.

To be summarized as evidence in this section, studies should have compared a fixed frequency and intensity of burning, but in different seasons (e.g. summer vs winter) or in different temporal patterns (e.g. 50% of marsh burned every summer vs 100% of marsh burned every other summer).

Study locations

Key messages

One study evaluated the effects, on vegetation, of burning freshwater marshes in different seasons or at different times. The study was in the USA.

VEGETATION COMMUNITY

Overall richness/diversity (1 study): One replicated, randomized, controlled study in a marsh in the USA found that spring-burned plots had greater plant species richness than summer-burned plots, at the end of the growing season.

VEGETATION ABUNDANCE

Overall abundance (1 study): One replicated, randomized, controlled study in a marsh in the USA found that spring-burned plots had greater overall vegetation cover than summer-burned plots, at the end of the growing season.
Individual species abundance (1 study): The same study reported that the cover and frequency of some individual plant species responded differently to spring vs summer burning.

VEGETATION STRUCTURE

About key messages

Key messages provide a descriptive index to studies we have found that test this intervention.

Studies are not directly comparable or of equal value. When making decisions based on this evidence, you should consider factors such as study size, study design, reported metrics and relevance of the study to your situation, rather than simply counting the number of studies that support a particular interpretation.

Supporting evidence from individual studies

A replicated, randomized, controlled study in 1992 in an ephemeral freshwater marsh in Missouri, USA (Laubhan 1995) found that spring-burned plots had greater plant species richness and overall vegetation cover than summer-burned plots at the end of the growing season, and supported a different abundance of individual plant species. At the end of September, spring-burned plots had greater plant species richness (5.5 species/m²) than summer-burned plots (2.6 species/m²). Spring-burned plots had greater overall vegetation cover (94%) than summer-burned plots (23%). The most abundant plant species in spring-burned plots included ricecut grass Leersia oryzoides (cover: 50%; frequency: 97%), beggarticks Bidens spp. (cover: 31%; frequency: 100%) and marsh elder Iva ciliata (cover: 17%; frequency: 90%). The most abundant species in summer-burned plots included ricecut grass (cover: 5%; frequency: 97%) and sesbania Sesbania exaltala (cover: 5%; frequency: 70%). Beggarticks and marsh elder each had <1% cover and occurred in only 3% of quadrats, on average. Methods: In 1992, six 0.1-ha plots were established in a freshwater marsh managed for waterfowl (i.e. winter flooding followed by spring or summer drawdown). Three random plots were burned in spring (early April) and three were burned in summer (late July). In the summer-burned plots, vegetation was mown three days before burning. Cover of every plant species, and bare ground, were recorded in late September 1992 in ten 1-m² quadrats/plot.
Study and other actions tested
Referenced paper
Laubhan M.K. (1995) Effects of prescribed fire on moist-soil vegetation and soil macronutrients. Wetlands, 15, 159-166.

Please cite as:

Taylor N.G., Grillas P., Smith R.K. & Sutherland W.J. (2021) Marsh and Swamp Conservation: Global Evidence for the Effects of Interventions to Conserve Marsh and Swamp Vegetation. Conservation Evidence Series Synopses. University of Cambridge, Cambridge, UK.

Where has this evidence come from?

List of journals searched by synopsis

All the journals searched for all synopses

This Action forms part of the Action Synopsis:

Marsh and Swamp Conservation

Related Actions

Actions	Effectiveness	Studies	Category
Change season/timing of prescribed burning: freshwater swamps Action Link	No evidence found (no assessment)	0	Synopsis Link
Change season/timing of prescribed burning: freshwater marshes Action Link	Unknown effectiveness (limited evidence)	1	Synopsis Link
Reduce frequency of cutting/mowing: brackish/salt marshes Action Link	No evidence found (no assessment)	0	Synopsis Link