| Popis: |
The present rate of global warming threatens the survival of entire ecoystems worldwide. Inhabiting the interface between land and sea, mangroves are amongst one of the most at-risk ecosystems when sea level rises. Although the effects of a sea level rise are presumed to be more significant, other climate change components like a rise in temperature, CO2 levels and precipitation will most likely have a major influence on mangrove productivity, phenology and distribution. This will consequently influence species-specific competition and adaptation to altered inundation conditions. In this study we present two parts regarding the effect of global climate change on mangroves (1) Can mangroves be resilient to sea level rise? Case study in Gazi Bay (Kenya) and (2) Temperature increase: what will happen at the latitudinal mangrove range limits in South-Africa and Brazil? Part (1) mainly focuses on the tidal range in order to forecast what will happen to mangrove vegetation assemblages under different 'Intergovernmental Panel for Climate Change (IPCC)' scenarios of sea level rise. Using experimental digital terrain modelling combined with water level simulations in a GIS environment and based on a detailed vegetation map, preliminary results are generated regarding the effect a sea level rise in the study site in Gazi Bay (Kenya). We adopt a reductionistic approach by taking abstraction of alterations in sedimentation and elevation and to other consequences of global change such as increases in temperature, in CO2 concentration and in storm frequency. Modelling of the different IPCC scenarios (whole bay) gave the overall trend of an area increase for all species (incl. the most typical and economically important Rhizophora assemblage, excl. Avicennia marina on the landward side) for the minumun, relative and average scenario. Under a sea-level rise scenario of +88 cm by the year 2100, the highest intertidal inundation class strongly decreases due to the topographical settings at the edge of the inhabitedarea. Consequently, the landward Avicennia-dominated assemblages will decrease if they fail to adapt to a more frequent inundation. Part (2) focuses on the latitudinal mangrove range limits in order to forecast what will happen to the limits under different IPCC scenarios of temperature increase. We focus on latitudinal range limits of Avicennia and Rhizophora genera. First of all, we look at the current temperature requirements of latitudinal mangrove range limits. Two limits in Brazil and South-Africa, where humidity is high yet not limiting, are choosen as case-studies. By combining the current temperature requirements with the different IPCC temperature scenarios for those regions, we predict the future mangrove limits. This is again a reductionistic approach by taking abstraction of mangrove dispersal requirements and all other consequences of global change (like sea level rise). Global warming will influence mangroves in many ways. There is a lack of data to study the total impact of all those factors on mangroves. In this poster we try to combine two major factors, namely sea level rise and temperature increase. Sea level rise will change the position and composition of mangrove forests, while temperature increase will change the mangrove range limits. |
