Abstract
Abstract. Mangrove forests prominently occupy an intertidal boundary position where the effects of sea level rise will be fast and well visible. This study in East Africa (Gazi Bay, Kenya) addresses the question of whether mangroves can be resilient to a rise in sea level by focusing on their potential to migrate towards landward areas. The combinatory analysis between remote sensing, DGPS-based ground truth and digital terrain models (DTM) unveils how real vegetation assemblages can shift under different projected (minimum (+9 cm), relative (+20 cm), average (+48 cm) and maximum (+88 cm)) scenarios of sea level rise (SLR). Under SLR scenarios up to 48 cm by the year 2100, the landward extension remarkably implies an area increase for each of the dominant mangrove assemblages except for Avicennia marina and Ceriops tagal, both on the landward side. On the one hand, the increase in most species in the first three scenarios, including the socio-economically most important species in this area, Rhizophora mucronata and C. tagal on the seaward side, strongly depends on the colonisation rate of these species. On the other hand, a SLR scenario of +88 cm by the year 2100 indicates that the area flooded only by equinoctial tides strongly decreases due to the topographical settings at the edge of the inhabited area. Consequently, the landward Avicennia-dominated assemblages will further decrease as a formation if they fail to adapt to a more frequent inundation. The topography is site-specific; however non-invadable areas can be typical for many mangrove settings.
Highlights
Inhabiting the interface between land and sea, mangroves are amongst one of the most at-risk ecosystems when sea level rises (McLeod and Salm 2006)
This study focuses on the critical factor “tidal range” in order to investigate the potential for landward migration of mangrove vegetation assemblages in Gazi Bay (Kenya) under different sea level rise (SLR) scenarios
Many researchers have already gathered valuable information within this study area on diverse subjects like regeneration, vegetation structure dynamics, human impacts and propagule dispersal (e.g. Abuodha and Kairo, 2001; Bosire et al, 2003, 2008b; Dahdouh-Guebas Farid and Koedam, 2006; Dahdouh-Guebas et al, 2002a; Di Nitto et al, 2008; Kairo et al, 2001; Kirui et al, 2008; Neukermans et al, 2008). The latter gives us the opportunity to draw preliminary conclusions on the potential for landward migration of mangroves in Gazi Bay and to create some views on the future vegetation structure dynamics, which can contribute to their resilience to SLR
Summary
Inhabiting the interface between land and sea, mangroves are amongst one of the most at-risk ecosystems when sea level rises (McLeod and Salm 2006). Ellison and Stoddart (1991) suggested that mangroves are stressed by SLRs of between 9 and 12 cm over 100 yr and concluded that faster rates could seriously threaten mangrove ecosystems. This view has been challenged by Snedaker et al (1994), who cited historical records showing changes nearly twice that high in mangrove expansion under relative sea level; hard scientific data or SLR simulations are not available.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
