Mangroves facing climate change: landward migration potential in response to projected scenarios of sea level rise
- 1Biocomplexity Research Focus c/o Laboratory of Plant Biology and Nature Management, Mangrove Management Group, Vrije Universiteit Brussel – VUB, Pleinlaan 2, 1050 Brussels, Belgium
- 2Laboratoire d'Écologie des Systèmes et Gestion des Ressources, Département de Biologie des Organismes, Faculté des Sciences, Université Libre de Bruxelles – ULB, CP 169, Avenue F.D. Roosevelt 50, 1050 Brussels, Belgium
- 3Laboratory of Physical Geography, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium
- 4Unité de Recherche Sciences de la Terre,Université libre de Bruxelles, Brussels, Belgium
- 5Kenya Marine and Fisheries Research Institute, P.O. Box 81651, Mombasa, Kenya
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.