The Effect of Fuel Moisture Content on the Flammability of Goldenrod in Prairie Ecosystems
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Date
2021-05
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Publisher
The Ohio State University
Abstract
Land use change across North America has greatly reduced the extent of prairies and grasslands and replaced them with agriculture. Grasslands and prairies provide biodiversity, habitat for many animals and pollinators, and ecosystem services. In Ohio, prairies did not have a large extent, but were known to exist in small patches representing the furthest reaches of western grasslands. Now, what is left of such prairies are small, remnants that lack resiliency and diversity, which makes restoring them necessary to conservation efforts.
Canadian goldenrod (Solidago canadensis) is a native species, but it can become invasive within restored prairies and old fields creating monocultures that reduce the species richness and diversity. Fire is likely a vital ecological disturbance within prairies, but goldenrod-dominated areas are may be difficult to ignite and burn. Goldenrod also greatly benefits from burns, due in part to suitable regeneration conditions created by fires and their early successional traits. To better understand fundamental controls on the potential for prescribed burning in restored prairies the flammability of goldenrod was investigated.
Field data was collected during spring and autumn 2019 to determine variation in fuel moisture content (FMC) with weather and how FMC varies vertically throughout the fuel bed. Weather data was taken on sampling days from Waterman Farm weather station and applied to the Canadian Forest Fire Danger Rating System to calculate the daily Fine Fuel Moisture Code (FFMC). Lab tests were conducted by heating samples of goldenrod of different FMCs in a quartz epiradiator and measuring ignitability, sustainability and combustibility. The impact of a pilot flame on ignition processes was also examined.
Goldenrod FMC was lowest at the top of the plants in spring, with greater fire danger ratings. Autumn FMC was not impacted by fire danger rating. Flammability tests showed that time to ignition was shortest at low FMCs. The duration of flaming and flame heights were greatest with lower FMCs. When comparing the flammability metrics to the FFMC values calculated from field data, there was a correlation between greater flammability and greater FFMC.
Overall, the results indicated that flammability was greatest at the lowest FMCs, specifically at around 15% and lower, which is a significant discovery. The flammability metrics determined that faster ignition, higher flame heights, and longer durations of flaming would likely lead to the spread of fire throughout fuels and greater consumption of goldenrod. Field data suggests that goldenrod has the lowest FMC in spring, at the top of the plant, which can alter fire behavior. Fine fuel moisture codes increased with decreasing FMCs and were positively correlated to flammability metrics. Fine fuel moisture codes of 70-74 and above strongly indicate increased flammability of goldenrod.
Description
2nd Place, Denman Research Forum
Keywords
Fire, Goldenrod, Prairies, Restoration, Prescribed Burn