ABSTRACT
Lake Tsizavatsy is located at the north of the Mangoky River, in the southwest of Madagascar (21.780ºS, 43.897ºE, at 45 m asl, Figure 1). The region has an extensive formation of sandstone eroded from the Precambrian basement and also less eroded tertiary limestones of marls and chalks from marine facies formed during the Eocene (Du Puy and Moat 1996; Moat and Smith 2007) that occur near the coast between 0 and 300 m asl. The region’s climate is characterised by semi-arid conditions with pronounced seasonality (Donque 1972) and annual precipitation ranging from 400–600 mm per year near the coast (Stiles 1998). The site’s vegetation is classified as tropical dry forests with patches of savanna and woodland savanna and some agricultural areas (Figure 1). These savannas include a small number of tree species belonging to the Arecaceae family that are highly adapted to fire, such as cf. Medemia nobilis (Grubb 2003). In addition, there is a patchy sclerophyllous forest which contains taxa such as Leptolaena spp. and a high number of dry adapted species such as those belonging to the Euphorbiaceae and Didiereaceae families (Moat and Smith 2007). Lake Tsizavatsy is a shallow lake of approximately 500 m in diameter. The local community reports that the lake recedes to half its area during the dry season. The lake did not exceed a depth of 0.5 m during our field work in September 2015. The studied sediment core provides a record of at least 10 km2 surrounding the lake representing local to landscape scale of vegetation change. The lake is surrounded by Cyperaceae at the margins and is encompassed by wooded savanna with the presence of degraded and intact dry forest in the wider landscape. Within and around the lake, taxa such as Phragmites mauritianum (Poaceae), Cryptostegia madagascariensi (Apocynaceae), Acacia morondavensis (Fabaceae), Hyphaene shatan (Arecaceae), and Euphorbia spp. (Euphorbiaceae) are found. The communities surrounding this area comprise foragers and maize horticulturalists (Mikea), agropastoralists (Masikoro), and fishers (Vezo).310
