Effect of wrack accumulation on salt marsh vegetation, Baruch Institute, Georgetown County, South Carolina

Abstract

In March 2004, four arrays in different types of salt marsh vegetation were covered with 15-20 cm of wrack secured in place, in an attempt to duplicate the natural deposition of wrack on the marsh by tides and storms, and to quantify and extend anecdotal observations and the results of previous studies. A control plot in each array was left uncovered; another plot was covered with only 2-3 cm. The wrack was removed from one plot in each array at one, two, four and seven month intervals. One month of wrack coverage appeared to have little effect on either density or standing crop, recorded seven months after initial covering, of the principal marsh species. Above ground parts of these species, with the exception of Spartina patens and Borrichia frutescens, appeared to be killed or extremely inhibited after two months of wrack coverage or longer. Wrack 2-3 cm thick (never removed) appeared to have inhibited the marsh species after seven months, but not as much as the 15-20 cm wrack mat. These results are fairly consistent with those of an earlier study at Jamaica Bay Wildlife Refuge, New York City, that focused on responses to wrack of Spartina alterniflora only, except that two months' coverage seemed necessary to kill back most of the S. alterniflora in that study. However, in another study at Jamaica Bay encompassing several species and vegetation types, most species declined gradually with increased length of wrack coverage over a six-month period. Future studies will focus on recovery of the vegetation once the wrack has been removed, and on chemical changes in the soil caused by the decaying wrack, which may in turn affect the future course of vegetation development.

Promoting Biotic Resistance in Seed-based Wetland Restoration Under Hydrologic Extremes

“…Finally, D. spicata, a perennial grass, was also able to survive both years of extreme weather at Farmington Bay. This nding is consistent with previous studies that found D. spicata to successfully survive both regular inundation(Stalter et al 2022) and extreme drought(McKee et al 2006).…”

Wrack and ruin: Legacy hydrologic effects of hurricane-deposited wrack on hardwood-hammock coastal islands

“…The effect of these deep (0.2 m to >2 m thick (Roman et al 1994, Guntenspergen et al 1995, Bush et al 1996, Platt et al 2015), persistent (often lasting years (Roman et al 1994, Guntenspergen et al 1995, Bush et al 1996, Platt et al 2015) wrack layers on precipitation inputs to the soils of upland ecosystems has not yet been investigated, but we hypothesize that they are large because even order-of-magnitude thinner organic litter layers heavily influence ecosystem water budgets Savenije 2011, Coenders-Gerrits et al 2020). Other ecological effects of wrack deposition, like the smothering of vegetation and altered habitat use by related fauna, have been previously described (Bertness and Ellison 1987, Roman et al 1994, Guntenspergen et al 1995, Bush et al 1996, Pennings and Richards 1998, Stalter et al 2005, Stalter et al 2006, Platt et al 2015.…”

The Dynamic Nature of Wrack: An Investigation into Wrack Movement and Impacts on Coastal Marshes Using sUAS

“…It took only three months for the wrack landscape in the marsh to look drastically different. While three months is a short time, there could still have been a negative impact on the vegetation [25]. In the experiment by Stalter et al (2006) [25], they found that vegetation struggles to recover after only two months of wrack burial.…”

“…It is widely held that tidal wrack can settle on living vegetation and have negative effects including killing the underlying vegetation. Studies have shown that when such disturbances occur for at least a three-to-four-month period, the risk of death to underlying vegetation increases, and devegetated areas can last for up to two years [23][24][25]. When wrack mats form into larger clusters of wrack mats, disturbances are more likely to lead to longer term damage to the marsh system [25].…”

“…Studies have shown that when such disturbances occur for at least a three-to-four-month period, the risk of death to underlying vegetation increases, and devegetated areas can last for up to two years [23][24][25]. When wrack mats form into larger clusters of wrack mats, disturbances are more likely to lead to longer term damage to the marsh system [25]. In addition, wrack can often contain plastics, debris, and other anthropogenic pollution that can further impact the vitality of the marsh ecosystem and species that depend on it [26].…”