The role of saltwort (Batis maritima L.) in regeneration of degraded mangrove forests

Abstract

While saltwort (Batis maritima L.) is common in the fringe mangrove forests of southwest Florida, its role in regeneration of degraded mangrove communities is not known. Given the potential encroachment and subsequent degradation of mangrove communities by sea-level rise, it is important to quantify the effect of early-colonizing vegetation to early mangrove seedling survival. A greater number of mangrove seedlings were observed in existing B. maritima patches compared to surrounding mudflats. A planting experiment was designed to determine whether B. maritima was responsible for the observed pattern. Black mangrove (Avicennia germinans L.) seedlings, raised in a nursery, were planted in previously established B. maritima patches and on mudflats with and without nursery-raised B. maritima. There was significantly lower mortality of A. germinans seedlings when planted in existing B. maritima patches (69%), compared to seedlings planted on the mudflats (93%), demonstrating that existing B. maritima improved A. germinans seedling survival. Nursery-raised B. maritima had lower mortality on open mudflats (28%), suggesting that it can tolerate conditions, which make it an early colonizer of newly available habitats. The primary mechanism proposed for improving seedling success is a slight increase in elevation provided by the dense root network of established B. maritima. These findings have implications for scientists and managers anticipating the response of mangroves to sea-level rise.

New perspectives on ecological mechanisms affecting coral recruitment on reefs

“…Another important ecological feature of B. maritima is its inability to tolerate prolonged periods of shade in mangrove-dominated wetlands (López-Portillo and Ezcurra, 1989). Along Florida's Gulf Coast, Milbrandt and Tinsley (2006) observed a greater number of black mangrove (Avicennia germinans (L.) Stearn) seedlings in existing B. maritima patches compared to surrounding mudfl ats. They hypothesized that this improved seedling success was the result of a slight increase in elevation provided by the B. maritima root system.…”

“…Studies in salt marshes near its northern limit found that it was not a dominant species and did not compete well with other marsh plants (Zedler, 1977). There is some suggestion that B. maritima may be a fugitive species because it is common in disturbed sites (Milbrandt and Tinsley, 2006). Pennings and Richards (1998), for example, found that stands of B. maritima were associated with areas that were disturbed by wracks of litter in a Georgia salt marsh.…”

“…If B. maritima facilitates the establishment of mangrove seedlings, we would expect a positive relationship between percent cover and the number of seedlings ϩ saplings for one or more of the mangrove species. Milbrandt and Tinsley (2006) found that the presence of B. maritima had a positive effect on the survival of A. germinans seedlings. , however, found that B. maritima had no effect on the recruitment and survival Sponge Community Dynamics on Caribbean Mangrove Roots: Signifi cance of Species Idiosyncrasies Janie L. Wulff ABSTRACT.…”

“…There have been at least two studies (Pennings and Richards, 1998;Milbrandt and Tinsley, 2006) suggesting that B. maritima is a fugitive species that colonizes high-light disturbed sites. In Belize, the highest percent cover was at the two disturbed sites and the Fringe habitat in the undisturbed mangroves (see Figure 2a).…”

Mangroves facing climate change: landward migration potential in response to projected scenarios of sea level rise

“…As in other transitional systems, plant establishment and community succession is driven by tolerance to physiological stress and plant-plant interactions (Bertness, 1991;Milbrandt and Tinsley, 2006); hence species-specific competition could signify a natural blockage for landward migration of mangroves. However, in several cases, facilitation is a common mechanism of succession in terrestrial habitats, meaning that an early coloniser changes the abiotic conditions in a way that allows an entry and finally a displacement of a second species to a previous intolerable habitat ( Connell and Slayter, 1977).…”