Chapter 3 : the Holocene vegetation history of the Maltese Islands

Abstract

The history of climate and environmental change in the lands around the Mediterranean Sea is dramatic, and our still emerging understanding has changed radically over the last 60 years and is still changing. Pioneering pollen work by Bonatti (1966) first provided evidence that relative to the Holocene (the last 11,500 years) the Late Pleistocene was a time of drought and cold in the region. But for many years alternative viewpoints held currency, especially the work of Vita-Finzi (1969) who held, on the basis of widespread Late Pleistocene gravels, that this had been a period of high precipitation. This view was finally laid to rest only in the 1980s and 1990s by further pollen work on lacustrine deposits (e.g. Bertoldi 1980; Bottema & Woldring 1984; Alessio et al. 1986; Follieri et al. 1988; Bottema et al. 1990), and analysis of the sedimentology and biotic components of Late Pleistocene gravels (e.g. Barker & Hunt 1995). Vita-Finzi (1969) did, however, pioneer the recognition of the scale and impact of climatic variability within the Holocene in countries bordering the Mediterranean at a time when most researchers thought of the period as extremely stable climatically. Recognition of this climatic variability and its impacts was made more complex because of very strong patterns of human impacts in some Mediterranean countries, which were difficult to disentangle unequivocally from the climatic signal (e.g. Hunt 1998; Grove & Rackham 2003). Only with the rise of isotope-based palaeoclimate studies and high-resolution dating did it become possible to separate the climatic and anthropogenic signals (e.g. Sadori et al. 2008). More recent work has started to show that within the Mediterranean Basin the overall trend and timing of Holocene climate change differs from region to region (Peyron et al. 2011). In broad terms, the northeast and southwest of the basin seem to be in phase, with a dry Early Holocene becoming more humid after c. 4000 cal. bc, while the northwest and southeast show an opposite trend with a wetter Early Holocene and progressive desiccation after c. 4000 cal. bc (Hunt et al. 2007). Within this very broad pattern there are considerable regional differences (e.g. Finné et al. 2011) and in the central Mediterranean, changes in seasonality are superimposed on these trends (Peyron et al. 2011, 2017). [excerpt]