Change season/timing of prescribed burning: freshwater marshes
Overall effectiveness category Awaiting assessment
Number of studies: 1
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).
Related actions: Reduce frequency of prescribed burning; Reduce intensity of prescribed burning; Use prescribed fire to maintain or restore disturbance; Use prescribed fire to control problematic plants.
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