1. The main drivers of elevation change were accretion on the marsh surface and subsurface movement below the root zone, but the relative influence of these processes varied temporally. Prior to Hurricanes Gustav and Ike (September 2008), the main driver was subsurface movement; after the hurricane, both accretion and subsurface movement were important.
2. Prior to Hurricanes Gustav and Ike, rates of elevation gain and accretion above a marker horizon were higher in burned plots compared to nonburned plots, whereas nutrient addition had no detectable influence on elevation dynamics.
3. Burning decreased standing and fallen plant litter, reducing fuel load. Hurricanes Gustav and Ike also removed fallen litter from all plots.
4. Aboveground and belowground production rates varied annually but were unaffected by burning and nutrient treatments.
5. Decomposition (of a standard cellulose material) in upper soil layers was increased in burned plots but was unaffected by nutrient treatments.
6. Soil physicochemistry was unaffected by burning or nutrient treatments.
7. The elevation deficit (difference between rate of submergence and vertical land development) prior to hurricanes was less in burned plots (6.2 millimeters per year [mm yr-1]) compared to nonburned plots (7.2 mm yr-1).
8. Storm sediments delivered by Hurricane Ike raised elevations an average of 7.4 centimeters (cm), which countered an elevation deficit that had accrued over 11 years.
Our findings provide preliminary insights into elevation dynamics occurring in brackish marshes of the Texas Chenier Plain under prescribed fire management. The results of this study indicate that prescribed burning conducted at 3- to 5-year intervals is not likely to negatively impact the long-term sustainability of S. patens-dominated brackish marshes at McFaddin National Wildlife Refuge and may offset existing elevation deficits by ≈ 1 mm yr-1. The primary drivers of elevation change varied in time and space, leading to a more complex situation in terms of predicting how disturbances may alter elevation trajectories. The potential effect of burning on elevation change in other marshes will depend on several site-specific factors, including geomorphic/ sedimentary setting, tide range, local rate of relative sea level rise, plant species composition, additional management practices (for example, for flood control), and disturbance types and frequency (for example, hurricanes or herbivore grazing). Increasing the scope of inference would require installation of SETs in replicate marshes undergoing different prescribed fire intervals and in different geomorphic settings (with different hurricane frequencies and/or different sedimentary settings). Multiple locations along the Gulf and Atlantic coasts where prescribed fire is used as a management tool could provide the appropriate setting for these installations.
Additional publication details
|Publication Subtype||USGS Numbered Series|
|Title||Effects of prescribed burning on marsh-elevation change and the risk of wetland loss|
|Series title||Open-File Report|
|Publisher||U.S. Geological Survey|
|Publisher location||Reston, VA|
|Contributing office(s)||National Wetlands Research Center|
|Description||vii, 51 p.|
|Online Only (Y/N)||Y|
|Additional Online Files (Y/N)||N|
|Google Analytic Metrics||Metrics page|